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Schülerfirmen sind eine verbreitete Unterrichtsmethode allgemeinbildender Schulen. Trotz ihrer Verbreitung und zunehmenden curricularen Verankerung ist der Forschungsstand bislang unbefriedigend. Ihr Potenzial für die ökonomische Bildung entfalten Schülerfirmen, wenn sie mit Beruflicher Orientierung und Entrepreneurship Education verbunden werden. Über die Wechselwirkungen zwischen diesen Aspekten ergeben sich zahlreiche handlungsorientierte Lehr-Lern-Situationen, mithilfe derer sowohl ökonomische als auch überfachliche Kompetenzförderung realisiert werden kann. Wesentliche Gestaltungsperspektiven werden im Beitrag identifiziert. Um die Fachlichkeit von Schülerfirmen sicher zu stellen, ist beispielsweise neben der Einbettung im Fachunterricht auch gut qualifiziertes Lehrpersonal erforderlich, da die Umsetzung von Schülerfirmen voraussetzungsreich ist.
Using dating apps has become popular for many young adults worldwide, promising the chance to meet new sexual partners. Because there is evidence that using dating apps may be associated with risky sexual behavior, this study compared users and non-users concerning their sexuality-related cognitions, namely their risky sexual scripts and sexual self-esteem, as well as their risky and sexually assertive behavior. It also explored the link between dating app use and acceptance of sexual coercion. A total of 491 young heterosexual adults (295 female) participated in an online survey advertised in social media and college libraries in Germany. Results indicated that users had more risky sexual scripts and reported more risky sexual behavior than non-users. Furthermore, male dating app users had lower sexual self-esteem and higher acceptance of sexual coercion than male non-users. In both gender groups, dating app use predicted casual sexual activity via a more risky casual sex script. Gender differences, potential underlying mechanisms, and directions for future research are discussed.
Conservation genetics can provide data needed by conservation practitioners for their decisions regarding the management of vulnerable or endangered species, such as the sun bear Helarctos malayanus. Throughout its range, the sun bear is threatened by loss and fragmentation of its habitat and the illegal trade of both live bears and bear parts. Sharply declining population numbers and population sizes, and a lack of natural dispersal between populations all threaten the genetic diversity of the remaining populations of this species. In this first population genetics study of sun bears using microsatellite markers, we analyzed 68 sun bear samples from Cambodia to investigate population structure and genetic diversity. We found evidence for two genetically distinct populations in the West and East of Cambodia. Ongoing or recent gene flow between these populations does not appear sufficient to alleviate loss of diversity in these populations, one of which (West Cambodia) is characterized by significant inbreeding. We were able to assign 85% of sun bears of unknown origin to one of the two populations with high confidence (assignment probability >= 85%), providing valuable information for future bear reintroduction programs. Further, our results suggest that developed land (mostly agricultural mosaics) acts as a barrier to gene flow for sun bears in Cambodia. We highlight that regional sun bear conservation action plans should consider promoting population connectivity and enforcing wildlife protection of this threatened species.
Rechtschreibung
(2019)
Speaking a late-learned second language (L2) is supposed to yield more variable and less consistent output than speaking one’s first language (L1), particularly with respect to reliably adhering to grammatical morphology. The current study investigates both internal processes involved in encoding morphologically complex words – by recording event-related brain potentials (ERPs) during participants’ silent productions – and the corresponding overt output. We specifically examined compounds with plural or singular modifiers in English. Thirty-one advanced L2 speakers of English (L1: German) were compared to a control group of 20 L1 English speakers from an earlier study. We found an enhanced (right-frontal) negativity during (silent) morphological encoding for compounds produced from regular plural forms relative to compounds formed from irregular plurals, replicating the ERP effect obtained for the L1 group. The L2 speakers’ overt productions, however, were significantly less consistent than those of the L1 speakers on the same task. We suggest that L2 speakers employ the same mechanisms for morphological encoding as L1 speakers, but with less reliance on grammatical constraints than L1 speakers.
User-generated content on social media platforms is a rich source of latent information about individual variables. Crawling and analyzing this content provides a new approach for enterprises to personalize services and put forward product recommendations. In the past few years, brands made a gradual appearance on social media platforms for advertisement, customers support and public relation purposes and by now it became a necessity throughout all branches. This online identity can be represented as a brand personality that reflects how a brand is perceived by its customers. We exploited recent research in text analysis and personality detection to build an automatic brand personality prediction model on top of the (Five-Factor Model) and (Linguistic Inquiry and Word Count) features extracted from publicly available benchmarks. The proposed model reported significant accuracy in predicting specific personality traits form brands. For evaluating our prediction results on actual brands, we crawled the Facebook API for 100k posts from the most valuable brands' pages in the USA and we visualize exemplars of comparison results and present suggestions for future directions.
This paper investigates the applicability of CMOS decoupling cells for mitigating the Single Event Transient (SET) effects in standard combinational gates. The concept is based on the insertion of two decoupling cells between the gate's output and the power/ground terminals. To verify the proposed hardening approach, extensive SPICE simulations have been performed with standard combinational cells designed in IHP's 130 nm bulk CMOS technology. Obtained simulation results have shown that the insertion of decoupling cells results in the increase of the gate's critical charge, thus reducing the gate's soft error rate (SER). Moreover, the decoupling cells facilitate the suppression of SET pulses propagating through the gate. It has been shown that the decoupling cells may be a competitive alternative to gate upsizing and gate duplication for hardening the gates with lower critical charge and multiple (3 or 4) inputs, as well as for filtering the short SET pulses induced by low-LET particles.
Enhancement of human induced pluripotent stem cells adhesion through multilayer laminin coating
(2019)
Bioengineered cell substrates are a highly promising tool to govern the differentiation of stem cells in vitro and to modulate the cellular behavior in vivo. While this technology works fine for adult stem cells, the cultivation of human induced pluripotent stem cells (hiPSCs) is challenging as these cells typically show poor attachment on the bioengineered substrates, which among other effects causes substantial cell death. Thus, very limited types of surfaces have been demonstrated suitable for hiPSC cultures. The multilayer coating approach that renders the surface with diverse chemical compositions, architectures, and functions can be used to improve the adhesion of hiPSCs on the bioengineered substrates. We hypothesized that a multilayer formation based on the attraction of molecules with opposite charges could functionalize the polystyrene (PS) substrates to improve the adhesion of hiPSCs. Polymeric substrates were stepwise coated, first with dopamine to form a polydopamine (PDA) layer, second with polylysine and last with Laminin-521. The multilayer formation resulted in the variation of hydrophilicity and chemical functionality of the surfaces. Hydrophilicity was detected using captive bubble method and the amount of primary and secondary amines on the surface was quantified by fluorescent staining. The PDA layer effectively immobilized the upper layers and thereby improved the attachment of hiPSCs. Cell adhesion was enhanced on the surfaces coated with multilayers, as compared to those without PDA and/or polylysine. Moreover, hiPSCs spread well over this multilayer laminin substrate. These cells maintained their proliferation capacity and differentiation potential. The multilayer coating strategy is a promising attempt for engineering polymer-based substrates for the cultivation of hiPSCs and of interest for expanding the application scope of hiPSCs.
In cloud computing, users are able to use their own operating system (OS) image to run a virtual machine (VM) on a remote host. The virtual machine OS is started by the user using some interfaces provided by a cloud provider in public or private cloud. In peer to peer cloud, the VM is started by the host admin. After the VM is running, the user could get a remote access to the VM to install, configure, and run services. For the security reasons, the user needs to verify the integrity of the running VM, because a malicious host admin could modify the image or even replace the image with a similar image, to be able to get sensitive data from the VM. We propose an approach to verify the integrity of a running VM on a remote host, without using any specific hardware such as Trusted Platform Module (TPM). Our approach is implemented on a Linux platform where the kernel files (vmlinuz and initrd) could be replaced with new files, while the VM is running. kexec is used to reboot the VM with the new kernel files. The new kernel has secret codes that will be used to verify whether the VM was started using the new kernel files. The new kernel is used to further measuring the integrity of the running VM.
Monitoring is a key prerequisite for self-adaptive software and many other forms of operating software. Monitoring relevant lower level phenomena like the occurrences of exceptions and diagnosis data requires to carefully examine which detailed information is really necessary and feasible to monitor. Adaptive monitoring permits observing a greater variety of details with less overhead, if most of the time the MAPE-K loop can operate using only a small subset of all those details. However, engineering such an adaptive monitoring is a major engineering effort on its own that further complicates the development of self-adaptive software. The proposed approach overcomes the outlined problems by providing generic adaptive monitoring via runtime models. It reduces the effort to introduce and apply adaptive monitoring by avoiding additional development effort for controlling the monitoring adaptation. Although the generic approach is independent from the monitoring purpose, it still allows for substantial savings regarding the monitoring resource consumption as demonstrated by an example.
The emergence of cloud computing allows users to easily host their Virtual Machines with no up-front investment and the guarantee of always available anytime anywhere. But with the Virtual Machine (VM) is hosted outside of user's premise, the user loses the physical control of the VM as it could be running on untrusted host machines in the cloud. Malicious host administrator could launch live memory dumping, Spectre, or Meltdown attacks in order to extract sensitive information from the VM's memory, e.g. passwords or cryptographic keys of applications running in the VM. In this paper, inspired by the moving target defense (MTD) scheme, we propose a novel approach to increase the security of application's sensitive data in the VM by continuously moving the sensitive data among several memory allocations (blocks) in Random Access Memory (RAM). A movement function is added into the application source code in order for the function to be running concurrently with the application's main function. Our approach could reduce the possibility of VM's sensitive data in the memory to be leaked into memory dump file by 2 5% and secure the sensitive data from Spectre and Meltdown attacks. Our approach's overhead depends on the number and the size of the sensitive data.
Leveraging spatio-temporal soccer data to define a graphical query language for game recordings
(2019)
For professional soccer clubs, performance and video analysis are an integral part of the preparation and post-processing of games. Coaches, scouts, and video analysts extract information about strengths and weaknesses of their team as well as opponents by manually analyzing video recordings of past games. Since video recordings are an unstructured data source, it is a complex and time-intensive task to find specific game situations and identify similar patterns. In this paper, we present a novel approach to detect patterns and situations (e.g., playmaking and ball passing of midfielders) based on trajectory data. The application uses the metaphor of a tactic board to offer a graphical query language. With this interactive tactic board, the user can model a game situation or mark a specific situation in the video recording for which all matching occurrences in various games are immediately displayed, and the user can directly jump to the corresponding game scene. Through the additional visualization of key performance indicators (e.g.,the physical load of the players), the user can get a better overall assessment of situations. With the capabilities to find specific game situations and complex patterns in video recordings, the interactive tactic board serves as a useful tool to improve the video analysis process of professional sports teams.
Rapid advances in location-acquisition technologies have led to large amounts of trajectory data. This data is the foundation for a broad spectrum of services driven and improved by trajectory data mining. However, for hybrid transactional and analytical workloads, the storing and processing of rapidly accumulated trajectory data is a non-trivial task. In this paper, we present a detailed survey about state-of-the-art trajectory data management systems. To determine the relevant aspects and requirements for such systems, we developed a trajectory data mining framework, which summarizes the different steps in the trajectory data mining process. Based on the derived requirements, we analyze different concepts to store, compress, index, and process spatio-temporal data. There are various trajectory management systems, which are optimized for scalability, data footprint reduction, elasticity, or query performance. To get a comprehensive overview, we describe and compare different exciting systems. Additionally, the observed similarities in the general structure of different systems are consolidated in a general blueprint of trajectory management systems.
Speaking the Unspeakable
(2019)
This article discusses the filmic representation of the infamous Wannsee Conference, when fifteen senior German officials met at a villa on the shore of a Berlin lake to discuss and co-ordinate the
implementation of the so-called final solution to the Jewish question. The understanding reached during the course of the ninety-minute meeting cleared the way for the Europe-wide killing of six million Jews. The article sets out to answer the principal challenge facing
anyone attempting to recreate the Wannsee Conference on film: what was the atmosphere of this conference and the attitude of the participants? Moreover, it discusses various ethical aspects related to the portrayal of evil, not in actions but in words, using the medium of film. In doing so, it focuses on the BBC/HBO television film Conspiracy (2001), directed by Frank Pierson, probing its historical accuracy and discussing its artistic credibility.
A digital filter is introduced which treats the problem of predictability versus time averaging in a continuous, seamless manner. This seamless filter (SF) is characterized by a unique smoothing rule that determines the strength of smoothing in dependence on lead time. The rule needs to be specified beforehand, either by expert knowledge or by user demand. As a result, skill curves are obtained that allow a predictability assessment across a whole range of time-scales, from daily to seasonal, in a uniform manner. The SF is applied to downscaled SEAS5 ensemble forecasts for two focus regions in or near the tropical belt, the river basins of the Karun in Iran and the Sao Francisco in Brazil. Both are characterized by strong seasonality and semi-aridity, so that predictability across various time-scales is in high demand. Among other things, it is found that from the start of the water year (autumn), areal precipitation is predictable with good skill for the Karun basin two and a half months ahead; for the Sao Francisco it is only one month, longer-term prediction skill is just above the critical level.
Ihre außergewöhnlich hohen Konversionseffizienzen von über 20 % und die einfache Zellherstellung machen Hybridperowskite zu heißen Kandidaten für alternative Solarzellenmaterialien. CH3NH3PbI3 als Archetyp dieser Materialklasse besitzt außergewöhnliche Eigenschaften wie eine sehr effiziente Umwandlung von Solarenergie, wobei besonders Ferroelektrizität als mögliche Erklärung in den Fokus gerückt ist. Diese erfordert allerdings eine nicht-zentrosymmetrische Kristallstruktur als notwendige Voraussetzung. Wir stellen hier eine Erklärung des Symmetriebruchs in diesem Material auf kristallographischem, d. h. fernordnungs-basiertem, Wege vor. Während das Molekülkation CH3NH3+ intrinsisch polar ist, ist es extrem fehlgeordnet und kann deshalb nicht die einzige Erklärung darstellen. Es verzerrt allerdings das umgebende Kristallgitter und ruft dadurch eine Verschiebung der Iod-Atome von den zentrosymmetrischen Positionen hervor.
Excellent conversion efficiencies of over 20% and facile cell production have placed hybrid perovskites at the forefront of novel solar cell materials, with CH3NH3PbI3 being an archetypal compound. The question why CH3NH3PbI3 has such extraordinary characteristics, particularly a very efficient power conversion from absorbed light to electrical power, is hotly debated, with ferroelectricity being a promising candidate. This does, however, require the crystal structure to be non-centrosymmetric and we herein present crystallographic evidence as to how the symmetry breaking occurs on a crystallographic and, therefore, long-range level. Although the molecular cation CH3NH3+ is intrinsically polar, it is heavily disordered and this cannot be the sole reason for the ferroelectricity. We show that it, nonetheless, plays an important role, as it distorts the neighboring iodide positions from their centrosymmetric positions.
Background: The distribution of pronouns varies cross-linguistically. This distribution has led to conflicting results in studies that investigated pronoun resolution in agrammatic indviduals. In the investigation of pronominal resolution, the linguistic phenomenon of "resumption" is understudied in agrammatism. The construction of pronominal resolution in Akan presents the opportunity to thoroughly examine resumption. Aims: To start, the present study examines the production of (pronominal) resumption in Akan focus constructions (who-questions and focused declaratives). Second, we explore the effect of grammatical tone on the processing of pronominal (resumption) since Akan is a tonal language. Methods & Procedures: First, we tested the ability to distinguish linguistic and non-linguistic tone in Akan agrammatic speakers. Then, we administered an elicitation task to five Akan agrammatic individuals, controlling for the structural variations in the realization of resumption: focused who-questions and declaratives with (i) only a resumptive pronoun, (ii) only a clause determiner, (iii) a resumptive pronoun and a clause determiner co-occurring, and (iv) neither a resumptive pronoun nor a clause determiner. Outcomes & Results: Tone discrimination .both for pitch and for lexical tone was unimpaired. The production task demonstrated that the production of resumptive pronouns and clause determiners was intact. However, the production of declarative sentences in derived word order was impaired; wh-object questions were relatively well-preserved. Conclusions: We argue that the problems with sentence production are highly selective: linguistic tones and resumption are intact but word order is impaired in non-canonical declarative sentences.
Entrepreneurial persistence is demonstrated by an entrepreneur’s continued positive maintenance of entrepreneurial motivation and constantly renewed active engagement in a new business venture despite counterforces or enticing alternatives. It thus is a crucial factor for entrepreneurs when pursuing and exploiting their business opportunities and in realizing potential economic gains and benefits. Using rich data on a representative sample of German business founders, we investigated the determinants of entrepreneurial persistence. Next to observed survival, we also constructed a hybrid persistence measure capturing the motivational dimension of persistence. We analyzed the influence of individual-level (human capital and personality) and business-related characteristics on both measures as well as their relative importance. We found that the two indicators emphasize different aspects of persistence. For the survival indicator, the predictive power was concentrated in business characteristics and human capital, while for hybrid persistence the dominant factors were business characteristics and personality. Finally, we showed that results were heterogeneous across subgroups. In particular, formerly unemployed founders did not differ in survival chances, but they were more likely to lack a high psychological commitment to their business ventures.
Den Ausbau gestalten
(2019)
Wendepunkt für Gesundheit
(2019)
Die Zukunft der Medizin
(2019)
Die Medizin im 21. Jahrhundert wird sich so schnell verändern wie nie zuvor – und mit ihr das Gesundheitswesen. Bahnbrechende Entwicklungen in Forschung und Digitalisierung werden die Auswertung und Nutzung riesiger Datenmengen in kurzer Zeit ermöglichen. Das wird unsere Kenntnisse über Gesundheit und gesund sein, sowie über die Entstehung, Prävention und Heilung von Krankheiten vollkommen verändern. Gleichzeitig wird sich die Art und Weise, wie Medizin praktiziert wird, fundamental verändern. Das Selbstverständnis nahezu aller Akteure wird sich rasch weiterentwickeln müssen. Das Gesundheitssystem wird in allen Bereichen umgebaut und teilweise neu erfunden werden. Digitale Transformation, Personalisierung und Prävention sind die Treiber der neuen Medizin.
Deutschland darf den Anschluss nicht verpassen. Im Vergleich mit anderen Ländern ist das deutsche Gesundheitswesen in vielen Punkten bedrohlich rückständig und fragmentiert. Um die Medizin und das Gesundheitswesen in Deutschland langfristig zukunftsfest zu machen, bedarf es vieler Anstrengungen – vor allem aber Offenheit gegenüber Veränderungen, sowie einen regulatorischen Rahmen, der ermöglicht, dass die medizinischen und digitalen Innovationen beim Patienten ankommen.
DIE ZUKUNFT DER MEDIZIN beschreibt Entwicklungen und Technologien, die die Medizin und das Gesundheitswesen im 21. Jahrhundert prägen werden. Das Buch informiert über die zum Teil dramatischen, disruptiven Innovationen in der Forschung, die durch Big Data, Künstliche Intelligenz und Robotik möglich werden.
Die Autoren sind führende Vordenker ihres Fachs und beschreiben aus langjähriger Erfahrung im In- und Ausland zukünftige Entwicklungen, die jetzt bereits greifbar sind.
The geochemical composition of oceanic basalts provides us with a window into the distribution of geochemical elements within the Earth’s mantle in space and time. In conjunction with a throughout knowledge on how the different elements behave e.g. during melt formation and evolution or on their partition behaviour between e.g. minerals and melts this information has been transformed into various models on how oceanic crust is formed along plume influenced or normal mid-ocean ridge segments, how oceanic crust evolves in response to seawater, on subduction recycling of oceanic crust and so forth. The work presented in this habilitation was aimed at refining existing models, putting further constraints on some of the major open questions in this field of research while at the same time trying to increase our knowledge on the behaviour of noble gases as a tracer for melt formation and evolution processes. In the line of this work the author and her co-workers were able to answer one of the major questions concerning the formation of oceanic crust along plume-influenced ridges – in which physical state does the plume material enter the ridge? Based on submarine volcanic glass He, Ne and Ar data, the author and her co-workers have shown that the interaction of mantle plumes with mid-ocean ridges occurs in the physical form of melts. In addition, the author and her co-workers have also put further constraints on one of the major questions concerning the formation of oceanic crust along normal mid-ocean ridges – namely how is the mid-ocean ridge system effectively cooled to form the lower oceanic crust? Based on Ne and Ar data in combination with Cl/K ratios of basaltic glass from the Mid-Atlantic ridge and estimates of crystallisation pressures they have shown, that seawater penetration reaches lower crustal levels close to the Moho, indicating that hydrothermal circulation might be an effective cooling mechanism even for the deep parts of the oceanic crust. Considering subduction recycling, the heterogeneity of the Earth’s mantle and mantle dynamic processes the key question is on which temporal and spatial scales is the Earth’s mantle geochemically heterogeneous? In the line of this work the author along with her co-workers have shown based on Cl/K ratios in conjunction with the Sr, Nd, and Pb isotopes of the OIBs representing the type localities for the different mantle endmembers that the quantity of Cl recycled into the mantle via subduction is not uniform and that neither the HIMU nor the EM1 and EM2 mantle components can be considered as distinct mantle endmembers. In addition, we have shown, based on He, Ne and Ar isotope and trace-element data from the Foundation hotspot that the near ridge seamounts of the Foundation seamount chain formed by the Foundation hotspot erupt lavas with a trace-element signature clearly characteristic of oceanic gabbro which indicates the existence of recycled, virtually unchanged lower oceanic crust in the plume source. This is a clear sign of the inefficiency of the stirring mechanism existing at mantle depth. Similar features are seen in other near-axis hotspot magmas around the world. Based on He, Sr, Nd, Pb and O isotopes and trace elements in primitive mafic dykes from the Etendeka flood basalts, NW Namibia the author along with her co-workers have shown that deep, less degassed mantle material carried up by a mantle plume contributed significantly to the flood basalt magmatism. The Etendeka flood basalts are part of the South Atlantic LIP, which is associated with the breakup of Gondwana, the formation of the Paraná-Etendeka flood basalts and the Walvis Ridge - Tristan da Cunha hotspot track. Thus reinforcing the lately often-challenged concept of mantle plumes and the role of mantle plumes in the formation of large igneous provinces. Studying the behaviour of noble gases during melt formation and evolution the author along with her co-workers has shown that He can be considerable more susceptible to changes during melt formation and evolution resulting not only in a complete decoupling of He isotopes from e.g. Ne or Pb isotopes but also in a complete loss of the primary mantle isotope signal. They have also shown that this decoupling occurs mainly during the melt formation processes requiring He to be more compatible during mantle melting than Ne. In addition, the author along with her co workers were able to show that incorporation of atmospheric noble gases into igneous rocks is in general a two-step process: (1) magma contamination by assimilation of altered oceanic crust results in the entrainment of air-equilibrated seawater noble gases; (2) atmospheric noble gases are adsorbed onto grain surfaces during sample preparation. This implies, considering the ubiquitous presence of the contamination signal, that magma contamination by assimilation of a seawater-sourced component is an integral part of mid-ocean ridge basalt evolution.
While the underlying mechanisms of Parkinson’s disease (PD) are still insufficiently studied, a complex interaction between genetic and environmental factors is emphasized. Nevertheless, the role of the essential trace element zinc (Zn) in this regard remains controversial. In this study we altered Zn balance within PD models of the versatile model organism Caenorhabditis elegans (C. elegans) in order to examine whether a genetic predisposition in selected genes with relevance for PD affects Zn homeostasis. Protein-bound and labile Zn species act in various areas, such as enzymatic catalysis, protein stabilization pathways and cell signaling. Therefore, total Zn and labile Zn were quantitatively determined in living nematodes as individual biomarkers of Zn uptake and bioavailability with inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) or a multi-well method using the fluorescent probe ZinPyr-1. Young and middle-aged deletion mutants of catp-6 and pdr-1, which are orthologues of mammalian ATP13A2 (PARK9) and parkin (PARK2), showed altered Zn homeostasis following Zn exposure compared to wildtype worms. Furthermore, age-specific differences in Zn uptake were observed in wildtype worms for total as well as labile Zn species. These data emphasize the importance of differentiation between Zn species as meaningful biomarkers of Zn uptake as well as the need for further studies investigating the role of dysregulated Zn homeostasis in the etiology of PD.
Determinations of the ultraviolet (UV) luminosity function of active galactic nuclei (AGN) at high redshifts are important for constraining the AGN contribution to reionization and understanding the growth of supermassive black holes. Recent inferences of the luminosity function suffer from inconsistencies arising from inhomogeneous selection and analysis of data. We address this problem by constructing a sample of more than 80 000 colour-selected AGN from redshift z= 0 to 7.5 using multiple data sets homogenized to identical cosmologies, intrinsic AGN spectra, and magnitude systems. Using this sample, we derive the AGN UV luminosity function from redshift z= 0 to 7.5. The luminosity function has a double power-law form at all redshifts. The break magnitude M-* shows a steep brightening from M-* similar to -24 at z = 0.7 to M-* similar to -29 at z = 6. The faint-end slope beta significantly steepens from -1.9 at z < 2.2 to -2.4 at z similar or equal to 6. In spite of this steepening, the contribution of AGN to the hydrogen photoionization rate at z similar to 6 is subdominant (< 3 per cent), although it can be non-negligible (similar to 10 per cent) if these luminosity functions hold down to M-1450 = -18. Under reasonable assumptions, AGN can reionize He II by redshift z = 2.9. At low redshifts (z < 0.5), AGN can produce about half of the hydrogen photoionization rate inferred from the statistics of HI absorption lines in the intergalactic medium. Our analysis also reveals important systematic errors in the data, which need to be addressed and incorporated in the AGN selection function in future in order to improve our results. We make various fitting functions, codes, and data publicly available.
Low-dimensional dynamics for higher-order harmonic, globally coupled phase-oscillator ensembles
(2019)
The Kuramoto model, despite its popularity as a mean-field theory for many synchronization phenomenon of oscillatory systems, is limited to a first-order harmonic coupling of phases. For higher-order coupling, there only exists a low-dimensional theory in the thermodynamic limit. In this paper, we extend the formulation used by Watanabe and Strogatz to obtain a low-dimensional description of a system of arbitrary size of identical oscillators coupled all-to-all via their higher-order modes. To demonstrate an application of the formulation, we use a second harmonic globally coupled model, with a mean-field equal to the square of the Kuramoto mean-field. This model is known to exhibit asymmetrical clustering in previous numerical studies. We try to explain the phenomenon of asymmetrical clustering using the analytical theory developed here, as well as discuss certain phenomena not observed at the level of first-order harmonic coupling.
The Chromospheric Telescope (ChroTel) is a small 10-cm robotic telescope at Observatorio del Teide on Tenerife (Spain), which observes the entire sun in Hα, Ca ii K, and He i 10 830 Å. We present a new calibration method that includes limb-darkening correction, removal of nonuniform filter transmission, and determination of He i Doppler velocities. Chromospheric full-disk filtergrams are often obtained with Lyot filters, which may display nonuniform transmission causing large-scale intensity variations across the solar disk. Removal of a 2D symmetric limb-darkening function from full-disk images results in a flat background. However, transmission artifacts remain and are even more distinct in these contrast-enhanced images. Zernike polynomials are uniquely appropriate to fit these large-scale intensity variations of the background. The Zernike coefficients show a distinct temporal evolution for ChroTel data, which is likely related to the telescope's alt-azimuth mount that introduces image rotation. In addition, applying this calibration to sets of seven filtergrams that cover the He i triplet facilitates the determination of chromospheric Doppler velocities. To validate the method, we use three datasets with varying levels of solar activity. The Doppler velocities are benchmarked with respect to cotemporal high-resolution spectroscopic data of the GREGOR Infrared Spectrograph (GRIS). Furthermore, this technique can be applied to ChroTel Hα and Ca ii K data. The calibration method for ChroTel filtergrams can be easily adapted to other full-disk data exhibiting unwanted large-scale variations. The spectral region of the He i triplet is a primary choice for high-resolution near-infrared spectropolarimetry. Here, the improved calibration of ChroTel data will provide valuable context data.
Zero-shot learning in Language & Vision is the task of correctly labelling (or naming) objects of novel categories. Another strand of work in L&V aims at pragmatically informative rather than "correct" object descriptions, e.g. in reference games. We combine these lines of research and model zero-shot reference games, where a speaker needs to successfully refer to a novel object in an image. Inspired by models of "rational speech acts", we extend a neural generator to become a pragmatic speaker reasoning about uncertain object categories. As a result of this reasoning, the generator produces fewer nouns and names of distractor categories as compared to a literal speaker. We show that this conversational strategy for dealing with novel objects often improves communicative success, in terms of resolution accuracy of an automatic listener.
Short period double degenerate white dwarf (WD) binaries with periods of less than similar to 1 day are considered to be one of the likely progenitors of type Ia supernovae. These binaries have undergone a period of common envelope evolution. If the core ignites helium before the envelope is ejected, then a hot subdwarf remains prior to contracting into a WD. Here we present a comparison of two very rare systems that contain two hot subdwarfs in short period orbits. We provide a quantitative spectroscopic analysis of the systems using synthetic spectra from state-of-the-art non-LTE models to constrain the atmospheric parameters of the stars. We also use these models to determine the radial velocities, and thus calculate dynamical masses for the stars in each system.
Already for decades it has been known that the winds of massive stars are inhomogeneous (i.e. clumped). To properly model observed spectra of massive star winds it is necessary to incorporate the 3-D nature of clumping into radiative transfer calculations. In this paper we present our full 3-D Monte Carlo radiative transfer code for inhomogeneous expanding stellar winds. We use a set of parameters to describe dense as well as the rarefied wind components. At the same time, we account for non-monotonic velocity fields. We show how the 3-D density and velocity wind inhomogeneities strongly affect the resonance line formation. We also show how wind clumping can solve the discrepancy between P v and H alpha mass-loss rate diagnostics.
The ability to work in teams is an important skill in today's work environments. In MOOCs, however, team work, team tasks, and graded team-based assignments play only a marginal role. To close this gap, we have been exploring ways to integrate graded team-based assignments in MOOCs. Some goals of our work are to determine simple criteria to match teams in a volatile environment and to enable a frictionless online collaboration for the participants within our MOOC platform. The high dropout rates in MOOCs pose particular challenges for team work in this context. By now, we have conducted 15 MOOCs containing graded team-based assignments in a variety of topics. The paper at hand presents a study that aims to establish a solid understanding of the participants in the team tasks. Furthermore, we attempt to determine which team compositions are particularly successful. Finally, we examine how several modifications to our platform's collaborative toolset have affected the dropout rates and performance of the teams.
While the IEEE 802.15.4 radio standard has many features that meet the requirements of Internet of things applications, IEEE 802.15.4 leaves the whole issue of key management unstandardized. To address this gap, Krentz et al. proposed the Adaptive Key Establishment Scheme (AKES), which establishes session keys for use in IEEE 802.15.4 security. Yet, AKES does not cover all aspects of key management. In particular, AKES comprises no means for key revocation and rekeying. Moreover, existing protocols for key revocation and rekeying seem limited in various ways. In this paper, we hence propose a key revocation and rekeying protocol, which is designed to overcome various limitations of current protocols for key revocation and rekeying. For example, our protocol seems unique in that it routes around IEEE 802.15.4 nodes whose keys are being revoked. We successfully implemented and evaluated our protocol using the Contiki-NG operating system and aiocoap.
Background: The polymorphism in FTO gene (rs9939609) is known to be associated with higher BMI and body fat mass content. However, environmental factors can modify this effect. The purpose of the present study was to investigate an association between sport specialization and the rs9939609 SNP in FTO gene in the cohort of professional and amateur young athletes. Methods: A total number of 250 young individuals 8-18 years old living in Moscow or Moscow district participated in the study. Individuals were divided into 3 groups in accordance with their physical activity level: control group (n = 49), amateurs (n = 67) and professionals (n = 137). Amateur and professional athletes were subdivided into groups according to their sport specialization. Quantile regression was used as a regression model, where the dependent (outcome) variable was BMI, along with percentage of body fat mass, and the independent variables (predictors) were the rs9939609 SNP in FTO gene, physical activity (active versus inactive), sport specialization (aerobic, intermittent sports and martial arts), nationality, level of sport experience (in years), gender and percentage of free fat mass content. Results: The regression analysis revealed that physical activity and sport specialization had greater impact compared to FTO allele in the group of physically active individuals. Physical activity, in particular aerobic, had negative associations with body fat mass and BMI. The rs9939609 SNP in FTO gene is associated with physical activity and aerobic activity. The magnitude of association becomes significantly larger at the upper quantiles of the body fat mass distribution. Conclusion: Physical activity and sport specialization explained more variance in body composition of physically active young individuals compared to the FTO polymorphism. Effect of interaction of physical activity, in particular aerobic, with the FTO polymorphism on body composition of young athletes was found.
A central claim by Hoerl & McCormack is that the temporal reasoning system is uniquely human. But why exactly? This commentary evaluates two possible options to justify the thesis that temporal reasoning is uniquely human, one based on considerations regarding agency and the other based on language. The commentary raises problems for both of these options.
Die gelingende Zusammenarbeit von Eltern und Lehrkräften gilt als eine wichtige Voraussetzung für den schulischen Bildungserfolg Lernender und wirkt sich zudem positiv auf die Beziehung von Lehrkräften und Lernenden aus. Der vorliegende Beitrag untersucht, inwiefern das Engagement von Klassenlehrkräften in der Zusammenarbeit mit Eltern, operationalisiert über angebotene formelle und informelle Kontakte, sowie die von Lernenden wahrgenommene Lehrer-Schüler-Beziehung mit der intrinsischen Motivation Lernender in Zusammenhang stehen. Ausgewertet wurden Daten von 881 Schülerinnen und Schülern aus 39 neunten und zehnten Klassen aus 13 Schulen der Sekundarstufe (Gymnasien und Integrierte Sekundarschulen). Manifestlatente Mehrebenenmodelle zeigen signi¿ kant positive Zusammenhänge zwischen der von Lehrkräften angebotenen Vielfalt formeller Kontakte und der intrinsischen Motivation der Lernenden auf Klassenebene. Auf Individualebene zeigen sich signi¿ kante positive Zusammenhänge zwischen der von Lernenden berichteten Lehrer-Schüler-Beziehung und der intrinsischen Motivation.
Lanthanide-doped upconverting nanoparticles (UCNP) are being extensively studied for bioapplications due to their unique photoluminescence properties and low toxicity. Interest in RET applications involving UCNP is also increasing, but due to factors such as large sizes, ion emission distributions within the particles, and complicated energy transfer processes within the UCNP, there are still many questions to be answered. In this study, four types of core and core-shell NaYF4-based UCNP co-doped with Yb3+ and Tm3+ as sensitizer and activator, respectively, were investigated as donors for the Methyl 5-(8-decanoylbenzo[1,2-d:4,5-d ']bis([1,3]dioxole)-4-yl)-5-oxopentanoate (DBD-6) dye. The possibility of resonance energy transfer (RET) between UCNP and the DBD-6 attached to their surface was demonstrated based on the comparison of luminescence intensities, band ratios, and decay kinetics. The architecture of UCNP influenced both the luminescence properties and the energy transfer to the dye: UCNP with an inert shell were the brightest, but their RET efficiency was the lowest (17%). Nanoparticles with Tm3+ only in the shell have revealed the highest RET efficiencies (up to 51%) despite the compromised luminescence due to surface quenching.
A new micro/mesoporous hybrid clay nanocomposite prepared from kaolinite clay, Carica papaya seeds, and ZnCl2 via calcination in an inert atmosphere is presented. Regardless of the synthesis temperature, the specific surface area of the nanocomposite material is between approximate to 150 and 300 m(2)/g. The material contains both micro- and mesopores in roughly equal amounts. X-ray diffraction, infrared spectroscopy, and solid-state nuclear magnetic resonance spectroscopy suggest the formation of several new bonds in the materials upon reaction of the precursors, thus confirming the formation of a new hybrid material. Thermogravimetric analysis/differential thermal analysis and elemental analysis confirm the presence of carbonaceous matter. The new composite is stable up to 900 degrees C and is an efficient adsorbent for the removal of a water micropollutant, 4-nitrophenol, and a pathogen, E. coli, from an aqueous medium, suggesting applications in water remediation are feasible.
Alluvial and transport-limited bedrock rivers constitute the majority of fluvial systems on Earth. Their long profiles hold clues to their present state and past evolution. We currently possess first-principles-based governing equations for flow, sediment transport, and channel morphodynamics in these systems, which we lack for detachment-limited bedrock rivers. Here we formally couple these equations for transport-limited gravel-bed river long-profile evolution. The result is a new predictive relationship whose functional form and parameters are grounded in theory and defined through experimental data. From this, we produce a power-law analytical solution and a finite-difference numerical solution to long-profile evolution. Steady-state channel concavity and steepness are diagnostic of external drivers: concavity decreases with increasing uplift rate, and steepness increases with an increasing sediment-to-water supply ratio. Constraining free parameters explains common observations of river form: to match observed channel concavities, gravel-sized sediments must weather and fine - typically rapidly - and valleys typically should widen gradually. To match the empirical square-root width-discharge scaling in equilibrium-width gravel-bed rivers, downstream fining must occur. The ability to assign a cause to such observations is the direct result of a deductive approach to developing equations for landscape evolution.
The size structure of autotroph communities - the relative abundance of small vs. large individuals - shapes the functioning of ecosystems. Whether common mechanisms underpin the size structure of unicellular and multicellular autotrophs is, however, unknown. Using a global data compilation, we show that individual body masses in tree and phytoplankton communities follow power-law distributions and that the average exponents of these individual size distributions (ISD) differ. Phytoplankton communities are characterized by an average ISD exponent consistent with three-quarter-power scaling of metabolism with body mass and equivalence in energy use among mass classes. Tree communities deviate from this pattern in a manner consistent with equivalence in energy use among diameter size classes. Our findings suggest that whilst universal metabolic constraints ultimately underlie the emergent size structure of autotroph communities, divergent aspects of body size (volumetric vs. linear dimensions) shape the ecological outcome of metabolic scaling in forest vs. pelagic ecosystems.
By using an integrative approach, we describe a new species of mayfly, Bungona (Chopralla) pontica sp. n., from Turkey. The discovery of a representative of the tropical mayfly genus Bungona in the Middle East is rather unexpected. The new species shows all the main morphological characters of the subgenus Chopralla, which has its closest related species occurring in southeastern Asia. Barcoding clearly indicated that the new species represents an independent lineage isolated for a very long time from other members of the complex. The claw is equipped with two rows of three or four flattened denticles. This condition is a unique feature of Bungona (Chopralla) pontica sp. n. among West Palaearctic mayfly species. Within the subgenus Chopralla, the species can be identified by the presence of a simple, not bifid right prostheca (also present only in Bungona (Chopralla) liebenauae (Soldan, Braasch & Muu, 1987)), the shape of the labial palp, and the absence of protuberances on pronotum.
Using two crystals for spontaneous parametric down-conversion in a parallel setup, we observe two-photon interference with high visibility. The high visibility is consistent with complementarity and the absence of which-path information. The observations are explained as the effects of entanglement or equivalently in terms of interfering probability amplitudes and also by the calculation of a second-order field correlation function in the Heisenberg picture. The latter approach brings out explicitly the role of the vacuum fields in the down-conversion at the crystals and in the photon coincidence counting. For comparison, we show that the Hong-Ou-Mandel dip can be explained by the same approach in which the role of the vacuum signal and idler fields, as opposed to entanglement involving vacuum states, is emphasized. We discuss the fundamental limitations of a theory in which these vacuum fields are treated as classical, stochastic fields.
We perform a detailed statistical analysis of diffusive trajectories of membrane-enclosed vesicles (vacuoles) in the supercrowded cytoplasm of living Acanthamoeba castellanii cells. From the vacuole traces recorded in the center-of-area frame of moving amoebae, we examine the statistics of the time-averaged mean-squared displacements of vacuoles, their generalized diffusion coefficients and anomalous scaling exponents, the ergodicity breaking parameter, the non-Gaussian features of displacement distributions of vacuoles, the displacement autocorrelation function, as well as the distributions of speeds and positions of vacuoles inside the amoeba cells. Our findings deliver novel insights into the internal dynamics of cellular structures in these infectious pathogens. Published under license by AIP Publishing.
A well-preserved sequence, by Archean standards, of mantle-derived metabasalts and metakomatiites forms large parts of the lower Onverwacht Group of the Barberton Greenstone Belt (South Africa). To elucidate the origin of mafic and ultramafic rocks from this 3.55 to 3.45 Ga sequence, we present a comprehensive geochemical dataset including major and trace elements as well as Lu-Hf and Sm-Nd isotope compositions for a variety of metavolcanic rocks. These include metabasalts of the amphibolite-facies Sandspruit and Theespruit Formations as well as metabasalts and metakomatiites of the lower greenschist-facies Komati Formation. Based on their incompatible trace element patterns, the basalts of the Sandspruit and Theespruit Formations can be subdivided into a light rare earth element (LREE) depleted group, a LREE-undepleted group, and a LREE-enriched group. Positive epsilon Hf-(t) and epsilon Nd-(t) values of ca. +3 to +4 and 0 to +2, respectively, together with depletions in Th and La-CN/Yb-CN indicate derivation of the LREE-depleted basalts from a depleted mantle source. However, chondritic epsilon Hf-(t) and epsilon Nd-(t) values combined with positive Th and La-CN/Yb-CN of the LREE-enriched samples indicate a contribution from older granitoid crust in the petrogenesis of these samples. Trace element patterns of komatiites and basalts of the Komati Formation are generally flat relative to primitive mantle with slight depletions in heavy rare earth elements and Th and overall positive epsilon Hf-(t) of + 2.5 +/- 3.5 (2 s.d.) and epsilon Nd-(t) of + 0.5 +/- 2.2 (2 s. d.). The coherence in trace element characteristics suggests a common magmatic origin for basalts and komatiites. This study reveals that the two lavas were derived from the same mantle plume, i. e. komatiites were formed by high degrees of melting of a depleted mantle source containing residual garnet and the basalts were formed by moderate degrees of partial melting in shallower regions of the mantle. Based on the current dataset, combined with published data, we propose a geodynamic model for the oldest units of the Barberton Greenstone Belt that describes the development from a submerged continental setting (for the Sandspruit and Theespruit Formations) to a submarine plateau setting (for the Komati Formation) as a consequence of continental rifting.
Hydroxyl terminated oligo(epsilon-caprolactone) (OCL) monolayers were reversibly cross-linked forming two dimensional networks (2D) at the air-water interface. The equilibrium reaction with glyoxal as the cross-linker is pH-sensitive. Pronounced contraction in the area of the prepared 2DOCL films in dependence of surface pressure and time revealed the process of the reaction. Cross-linking inhibited crystallization and retarded enzymatic degradation of the OCLfilm. Altering the subphase pH led to a cleavage of the covalent acetal cross-links. The reversibility of the covalent acetal cross-links was proved by observing an identical isotherm as non-cross-linked sample. Besides as model systems, these customizable reversible OCL2D networks are intended for use as pHresponsive drug delivery systems or functionalized cell culture substrates.
Background: There is a growing interest in the role of inflammageing for chronic disease development. Cytokines are potent soluble immune mediators that can be used as target biomarkers of inflammageing; however, their measurement in human samples has been challenging. This study aimed to assess the reliability of a pro- and anti-inflammatory cytokine panel in a sample of healthy people measured with a novel electrochemiluminescent multiplex immunoassay platform (Meso Scale Discovery, MSD), and to characterize their associations with metabolic and inflammatory phenotypes.
The present article reports four experiments that investigated the effects of task-unrelated thoughts (TUTs) on forgetting in non-verbal working memory. Participants had to remember three non-verbal stimuli over unfilled retention intervals (RIs) and then judge whether or not a subsequently presented probe stimulus matched one of the to-be-remembered stimuli. Participants additionally responded to randomly appearing probes that measured different aspects of their TUT engagement during the RI of the preceding trial. Forgetting over unfilled RIs was observed in three of four experiments and reliably associated with the proportion of time spent on TUTs. In contrast, the visual and auditory nature of the TUTs and the number of different TUTs did not reliably predict forgetting. The results support the view that TUTs block attention-based processes that are needed for restoring decaying memory representations rather than an alternative account in terms of interference caused by the content of the TUTs.
In older persons, the origin of malnutrition is often multifactorial with a multitude of factors involved. Presently, a common understanding about potential causes and their mode of action is lacking, and a consensus on the theoretical framework on the etiology of malnutrition does not exist. Within the European Knowledge Hub "Malnutrition in the Elderly (MaNuEL)," a model of "Determinants of Malnutrition in Aged Persons" (DoMAP) was developed in a multistage consensus process with live meetings and written feedback (modified Delphi process) by a multiprofessional group of 33 experts in geriatric nutrition. DoMAP consists of three triangle-shaped levels with malnutrition in the center, surrounded by the three principal conditions through which malnutrition develops in the innermost level: low intake, high requirements, and impaired nutrient bioavailability. The middle level consists of factors directly causing one of these conditions, and the outermost level contains factors indirectly causing one of the three conditions through the direct factors. The DoMAP model may contribute to a common understanding about the multitude of factors involved in the etiology of malnutrition, and about potential causative mechanisms. It may serve as basis for future research and may also be helpful in clinical routine to identify persons at increased risk of malnutrition.
Climate science is highly interdisciplinary by nature, so understanding interactions between Earth processes inherently warrants the use of analytical software that can operate across the disciplines of Earth science. Toward this end, we present the Climate Data Toolbox for MATLAB, which contains more than 100 functions that span the major climate-related disciplines of Earth science. The toolbox enables streamlined, entirely scriptable workflows that are intuitive to write and easy to share. Included are functions to evaluate uncertainty, perform matrix operations, calculate climate indices, and generate common data displays. Documentation is presented pedagogically, with thorough explanations of how each function works and tutorials showing how the toolbox can be used to replicate results of published studies. As a well-tested, well-documented platform for interdisciplinary collaborations, the Climate Data Toolbox for MATLAB aims to reduce time spent writing low-level code, let researchers focus on physics rather than coding and encourage more efficacious code sharing. Plain Language Summary This article describes a collection of computer code that has recently been released to help scientists analyze many types of Earth science data. The code in this toolbox makes it easy to investigate things like global warming, El Nino, or other major climate-related processes such as how winds affect ocean circulation. Although the toolbox was designed to be used by expert climate scientists, its instruction manual is well written, and beginners may be able to learn a great deal about coding and Earth science, simply by following along with the provided examples. The toolbox is intended to help scientists save time, help them ensure their analysis is accurate, and make it easy for other scientists to repeat the results of previous studies.
The Cumbres Calchaquies Range forms part of the Famatinian metamorphic basement of the Eastern Sierras Pampeanas. The sedimentary protoliths of the metamorphic sequence were deposited in a marine basin alongside the western margin of Gondwana during the Neoproterozoic. New petrologic, geochemical and thermobarometric data give insight into the evolution of the sedimentary basin, its sediment source area, its later metamorphic overprint and its regional relationship to other parts of the Famatinian basement. The metamorphic series studied here consists of banded schists and gneisses and rare calcsilcate-rocks and migmatites that have been reworked by mid-to deep-crustal metamorphic and tectonic processes. The bulk rock compositions indicate shale, wacke, marl and litharenitic protoliths. The metamorphosed elastic sediments have major and trace element compositions indicating a continental granitoid-dominated source area with low sediment recycling. Low SiO2/Al2O3 ratios suggest a relatively low maturity of the sedimentary protoliths. Therefore, the Cumbres Calchaquies section represents a sequence of turbidity currents with progressive shallowing of the depositional environment, as indicated by quartz- and carbonate-rich sediments. The overall data are consistent with the geodynamic environment of a basin adjacent to a continental magmatic arc as the most probable scenario. Whereas the sedimentary protoliths of the metamorphic basement in the Sierra de Ancasti and Sierra de Aconquija, located ca 100-300 km south of the study area are interpreted as originating in an evolving back-arc basin, our results from the Cumbres Calchaquies region indicate a sedimentary source in a felsic continental arc with no significant influx of basic rocks. The Famatinian metamorphic evolution of the Cumbres Calchaquies rocks is of typical Barrow-type, culminating in partial melting of the metasediments. Conventional thermobarometry combined with thermodynamic models (pseudosections) reveal a prograde evolution reaching peak conditions of ca 665 degrees C/6.1 Kbar. This implies a geothermal gradient of ca 35 degrees C/km, which is slightly higher than the average for continental crust and suggests a period of crustal thinning, as known from back-arc basins, or additional heat supply by voluminous intrusions.
Stable carbon isotopes of sediment organic matter (delta C-13(OM)) are widely applied in paleoenvironmental studies. Interpretations of delta C-13(OM), however, remain challenging and factors that influence delta C-13(OM) may not apply across all lakes. Common explanations for stratigraphic shifts in delta C-13(OM) include changes in lake productivity or changes in inputs of allochthonous OM. We investigated the influence of different oxygen conditions (oxic versus anoxic) on the delta C-13(OM) values in the sediments of Lake Tiefer See. We analysed (1) a long sediment core from the deepest part of the lake, (2) two short, sediment-water interface cores from shallower water depths, and (3) OM in the water column, i.e. from sediment traps. Fresh OM throughout the entire water column showed a relatively constant delta C-13(OM) value of approximately -30.5 parts per thousand. Similar values, about -31 parts per thousand, were obtained for well-varved sediments in both the long and short, sediment-water interface cores. In contrast, delta C-13(OM) values from non-varved sediments in all cores were significantly less negative (-29 parts per thousand). The delta C-13(OM) values in the sediment-water interface cores from different water depths differ for sediments of the same age, if oxygen conditions at the time of deposition were different at these sites, as suggested by the state of varve preservation. Sediments deposited from AD 1924 to 1980 at 62m water depth are varved and exhibit delta C-13(OM) values around -31 parts per thousand, whereas sediments of the same age in the core from 35m water depth are not varved and show less negative delta C-13(OM) values of about -29 parts per thousand. The relation between varve occurrence and delta C-13(OM) values suggests that delta C-13(OM) is associated with oxygen conditions because varve preservation depends on hypolimnetic anoxia. A mechanism that likely influences delta C-13(OM) is selective degradation of OM under oxic conditions, such that organic components with more negative delta C-13(OM) are preferably decomposed, leading to less negative delta C-13(OM) values in the remaining, undegraded OM pool. Greater decomposition of OM in non-varved sediments is supported by lower TOC concentrations in these deposits (similar to 5%) compared to well-varved sediments (similar to 15%). Even in lakes that display small variations in productivity and terrestrial OM input through time, large spatial and temporal differences in hypolimnetic oxygen concentrations may be an important factor controlling sediment delta C-13(OM).
The principle of encapsulation/release of a guest molecule from stimuli responsive hydrogels (SRHs) is mainly realised with pH, temperature or light stimuli. However, only a limited number of redox responsive hydrogels have been investigated so far. We report here the development of a SRH that can release its guest molecule upon a redox stimulus. To obtain this redox hydrogel, we have introduced into the hydrogel the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) stable nitroxide radical, which can be reversibly oxidized into an oxoammonium cation (TEMPO+). Water solubility is provided by the presence of the (oligoethyleneglycol)methacrylate (OEGMA) comonomer. Electrochemical and mechanical characterization showed that those gels exhibit interesting physicochemical properties, making them very promising candidates for practical use in a wide range of applications.
Following the Middle Permian (Capitanian) mass extinction there was a global ‘reef eclipse’, and this event had an important role in the Paleozoic-Mesozoic transition of reef ecosystems. Furthermore, the recovery pattern of reef ecosystems in the Wuchiapingian of South China, before the radiation of Changhsingian reefs, is poorly understood. Here, we present a detailed sedimentological account of the Tieqiao section, South China, which records the only known Wuchiapingian reef setting from South China. Six reef growing phases were identified within six transgressive-regressive cycles. The cycles represent changes of deposition in a shallow basin to a subtidal outer platform setting, and the reefal build-ups are recorded in the shallowest part of the cycles above wave base in the euphotic zone. Our results show that the initial reef recovery started from the shallowing up part of the 1st cycle, within the Clarkina leveni conodont zone, which is two conodont zones earlier than previously recognized. In addition, even though metazoans, such as sponges, do become important in the development of the reef bodies, they are not a major component until later in the Wuchiapingian in the 5th and 6th transgressive-regressive cycles. This suggests a delayed recovery of metazoan reef ecosystems following the Middle Permian extinction. Furthermore, even though sponges do become abundant within the reefs, it is the presence and growth of the encrusters Archaeolithoporella and Tubiphytes and abundance of microbial micrites that play an important role in stabilizing the reef structures that form topographic highs.
What comes NeXT?
(2019)
Here, we report on a new record in the acquisition time for fast neutron tomography. With an optimized imaging setup, it was possible to acquire single radiographic projection images with 10 ms and full tomographies with 155 projections images and a physical spatial resolution of 200 mu m within 1.5 s. This is about 6.7 times faster than the current record. We used the technique to investigate the water infiltration in the soil with a living lupine root system. The fast imaging setup will be part of the future NeXT instrument at ILL in Grenoble with a great field of possible future applications. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Tissue transglutaminase (TGase 2) is proposed to be important for biomaterial-tissue interactions due to its presence and versatile functions in the extracellular environment. TGase 2 catalyzes the cross-linking of proteins through its Ca2+-dependent acyltransferase activity. Moreover, it enhances the interactions between fibronectin and integrins, which in turn mediates the adhesion, migration, and motility of the cells. TGase 2 is also a key player in the pathogenesis of fibrosis. In this study, we investigated whether TGase 2 is present at the biomaterial tissue interface and might serve as an informative biomarker for the visualization of tissue response toward gelatin-based biomaterials. Two differently cross-linked hydrogels were used, which were obtained by the reaction of gelatin with lysine diisocyanate ethyl ester. The overall expression of TGase 2 by endothelial cells, macrophages, and granulocytes was partly influenced by contact to the hydrogels or their degradation products, although no clear correlation was evidenced. In contrast, the secretion of TGase 2 differed remarkably between the different cells, indicating that it might be involved in the cellular reaction toward gelatin-based hydrogels. The hydrogels were implanted subcutaneously in immunocompetent, hairless SKH1-Elite mice. Ex vivo immunohistochemical analysis of tissue sections over 112 days revealed enhanced expression of TGase 2 around the hydrogels, in particular at days 14 and 21 post-implantation. The incorporation of fluorescently labeled cadaverine derivatives for the detection of active TGase 2 was in accordance with the results of the expression analysis. The presence of an irreversible inhibitor of TGase 2 led to attenuated incorporation of the cadaverines, which verified the catalytic action of TGase 2. Our in vitro and ex vivo results verified TGase 2 as a potential biomarker for tissue response toward gelatin-based hydrogels. In vivo, no TGase 2 activity was detectable, which is mainly attributed to the unfavorable physicochemical properties of the cadaverine probe used.
Gamma-ray bursts (GRBs) are brief flashes of gamma-rays and are considered to be the most energetic explosive phenomena in the Universe(1). The emission from GRBs comprises a short (typically tens of seconds) and bright prompt emission, followed by a much longer afterglow phase. During the afterglow phase, the shocked outflow-produced by the interaction between the ejected matter and the circumburst medium-slows down, and a gradual decrease in brightness is observed(2). GRBs typically emit most of their energy via.-rays with energies in the kiloelectronvolt-to-megaelectronvolt range, but a few photons with energies of tens of gigaelectronvolts have been detected by space-based instruments(3). However, the origins of such high-energy (above one gigaelectronvolt) photons and the presence of very-high-energy (more than 100 gigaelectronvolts) emission have remained elusive(4). Here we report observations of very-high-energy emission in the bright GRB 180720B deep in the GRB afterglow-ten hours after the end of the prompt emission phase, when the X-ray flux had already decayed by four orders of magnitude. Two possible explanations exist for the observed radiation: inverse Compton emission and synchrotron emission of ultrarelativistic electrons. Our observations show that the energy fluxes in the X-ray and gamma-ray range and their photon indices remain comparable to each other throughout the afterglow. This discovery places distinct constraints on the GRB environment for both emission mechanisms, with the inverse Compton explanation alleviating the particle energy requirements for the emission observed at late times. The late timing of this detection has consequences for the future observations of GRBs at the highest energies.
Magnetically doped topological insulators enable the quantum anomalous Hall effect (QAHE), which provides quantized edge states for lossless charge-transport applications(1-8). The edge states are hosted by a magnetic energy gap at the Dirac point(2), but hitherto all attempts to observe this gap directly have been unsuccessful. Observing the gap is considered to be essential to overcoming the limitations of the QAHE, which so far occurs only at temperatures that are one to two orders of magnitude below the ferromagnetic Curie temperature, T-C (ref. (8)). Here we use low-temperature photoelectron spectroscopy to unambiguously reveal the magnetic gap of Mn-doped Bi2Te3, which displays ferromagnetic out-of-plane spin texture and opens up only below T-C. Surprisingly, our analysis reveals large gap sizes at 1 kelvin of up to 90 millielectronvolts, which is five times larger than theoretically predicted(9). Using multiscale analysis we show that this enhancement is due to a remarkable structure modification induced by Mn doping: instead of a disordered impurity system, a self-organized alternating sequence of MnBi2Te4 septuple and Bi2Te3 quintuple layers is formed. This enhances the wavefunction overlap and size of the magnetic gap(10). Mn-doped Bi2Se3 (ref. (11)) and Mn-doped Sb2Te3 form similar heterostructures, but for Bi2Se3 only a nonmagnetic gap is formed and the magnetization is in the surface plane. This is explained by the smaller spin-orbit interaction by comparison with Mn-doped Bi2Te3. Our findings provide insights that will be crucial in pushing lossless transport in topological insulators towards room-temperature applications.
Although there is ample evidence linking insecure attachment styles and intimate partner violence (IPV), little is known about the psychological processes underlying this association, especially from the victim’s perspective. The present study examined how attachment styles relate to the experience of sexual and psychological abuse, directly or indirectly through destructive conflict resolution strategies, both self-reported and attributed to their opposite-sex romantic partner. In an online survey, 216 Spanish undergraduates completed measures of adult attachment style, engagement and withdrawal conflict resolution styles shown by self and partner, and victimization by an intimate partner in the form of sexual coercion and psychological abuse. As predicted, anxious and avoidant attachment styles were directly related to both forms of victimization. Also, an indirect path from anxious attachment to IPV victimization was detected via destructive conflict resolution strategies. Specifically, anxiously attached participants reported a higher use of conflict engagement by themselves and by their partners. In addition, engagement reported by the self and perceived in the partner was linked to an increased probability of experiencing sexual coercion and psychological abuse. Avoidant attachment was linked to higher withdrawal in conflict situations, but the paths from withdrawal to perceived partner engagement, sexual coercion, and psychological abuse were non-significant. No gender differences in the associations were found. The discussion highlights the role of anxious attachment in understanding escalating patterns of destructive conflict resolution strategies, which may increase the vulnerability to IPV victimization.
Word forms such as walked or walker are decomposed into their morphological constituents (walk + -ed/-er) during language comprehension. Yet, the efficiency of morphological decomposition seems to vary for different languages and morphological types, as well as for first and second language speakers. The current study reports results from a visual masked priming experiment focusing on different types of derived word forms (specifically prefixed vs. suffixed) in first and second language speakers of German. We compared the present findings with results from previous studies on inflection and compounding and proposed an account of morphological decomposition that captures both the variability and the consistency of morphological decomposition for different morphological types and for first and second language speakers. Open Practices This article has been awarded an Open Materials badge. Study materials are publicly accessible via the Open Science Framework at . Learn more about the Open Practices badges from the Center for Open Science: .
Vermetid reefs and rocky shores are hot spots of biodiversity, often referred to as the subtropical equivalent of coral reefs. The development of the ecosystem depends on the activity of several reef builders, including red crustose coralline algae (CCA) such as Neogoniolithon brassica-florida. Despite its importance, little is known about Neogoniolithon sp. acclimation to rapid changes in light intensity and corresponding photosynthetic activity. To overcome the large spatial variability in the light field (due to location and the porous nature of the rocks) we grew Neogoniolithon sp. on glass slides and characterized its photosynthetic performance in response to various light intensities by following O-2 exchange and fluorescence parameters. This was also performed on rock-inhabiting thalli collected from the east Mediterranean basin. Generally, maximal photosynthetic rate was reached when Neogoniolithon sp. thalli grown under low illumination (such as in protected niches where the light intensity can be as low as 1% of surface illumination) were examined. When exposed to light intensities higher than those experienced during growth, Neogoniolithon sp. activates adaptive/protective mechanisms such as state transition and nonphotochemical fluorescence quenching and increases the dark respiration thereafter. We find that the Fv/Fm parameter (variable/maximal fluorescence) is not suitable to assess photosynthetic performance in Neogoniolithon sp. and propose using instead an alternative parameter recently developed. Our findings help to clarify why Neogoniolithon sp. is usually observed in shaded niches along the reef surfaces.
Let (M-i, g(i))(i is an element of N) be a sequence of spin manifolds with uniform bounded curvature and diameter that converges to a lower-dimensional Riemannian manifold (B, h) in the Gromov-Hausdorff topology. Then, it happens that the spectrum of the Dirac operator converges to the spectrum of a certain first-order elliptic differential operator D-B on B. We give an explicit description of D-B and characterize the special case where D-B equals the Dirac operator on B.
Understanding the strategies employed by plant species that live in extreme environments offers the possibility to discover stress tolerance mechanisms. We studied the physiological, antioxidant and metabolic responses to three temperature conditions (4, 15, and 23 degrees C) of Colobanthus quitensis (CQ), one of the only two native vascular species in Antarctica. We also employed Dianthus chinensis (DC), to assess the effects of the treatments in a non-Antarctic species from the same family. Using fused LASSO modelling, we associated physiological and biochemical antioxidant responses with primary metabolism. This approach allowed us to highlight the metabolic pathways driving the response specific to CQ. Low temperature imposed dramatic reductions in photosynthesis (up to 88%) but not in respiration (sustaining rates of 3.0-4.2 mu mol CO2 m(-2) s(-1)) in CQ, and no change in the physiological stress parameters was found. Its notable antioxidant capacity and mitochondrial cytochrome respiratory activity (20 and two times higher than DC, respectively), which ensure ATP production even at low temperature, was significantly associated with sulphur-containing metabolites and polyamines. Our findings potentially open new biotechnological opportunities regarding the role of antioxidant compounds and respiratory mechanisms associated with sulphur metabolism in stress tolerance strategies to low temperature.
This study aims to identify the best-performing site characterization proxy alternative and complementary to the conventional 30 m average shear-wave velocity V-S30, as well as the optimal combination of proxies in characterizing linear site response. Investigated proxies include T-0 (site fundamental period obtained from earthquake horizontal-to-vertical spectral ratios), V-Sz (measured average shear-wave velocities to depth z, z = 5, 10, 20 and 30 m), Z(0.8) and Z(1.0) (measured site depths to layers having shear-wave velocity 0.8 and 1.0 km/s, respectively), as well as Z(x-infer) (inferred site depths from a regional velocity model, x = 0.8 and 1.0, 1.5 and 2.5 km/s). To evaluate the performance of a site proxy or a combination, a total of 1840 surface-borehole recordings is selected from KiK-net database. Site amplifications are derived using surface-to-borehole response-, Fourier- and cross-spectral ratio techniques and then are compared across approaches. Next, the efficacies of 7 single-proxies and 11 proxy-pairs are quantified based on the site-to-site standard deviation of amplification residuals of observation about prediction using the proxy or the pair. Our results show that T-0 is the best-performing single-proxy among T-0, Z(0.8), Z(1.0) and V-Sz. Meanwhile, T-0 is also the best-performing proxy among T-0, Z(0.8), Z(1.0) and Z(x-infer) complementary to V-S30 in accounting for the residual amplification after V-S30-correction. Besides, T-0 alone can capture most of the site effects and should be utilized as the primary site indicator. Though (T-0, V-S30) is the best-performing proxy pair among (V-S30, T-0), (V-S30, Z(0.8)), (V-S30, Z(1.0)), (V-S30, Z(x-infer)) and (T-0, V-Sz), it is only slightly better than (T-0, V-S20). Considering both efficacy and engineering utility, the combination of T-0 (primary) and V-S20 (secondary) is recommended. Further study is needed to test the performances of various proxies on sites in deep sedimentary basins.
A series of phenolic-acid-based 2-oxazoline monomers with methoxy-substituted phenyl and cinnamyl side chains is synthesized and polymerized in a microwave reactor at 140 °C using methyl tosylate as the initiator. The obtained poly(2-oxazoline)s are characterized by NMR spectroscopy, MALDI-TOF mass spectrometry, and size-exclusion chromatography (SEC). Kinetic studies reveal that the microwave-assisted polymerization is fast and completed within less than ≈10 min for low monomer-to-initiator ratios of ≤25. Polymers with number-average molar masses of up to 6500 g mol−1 and low dispersity (1.2–1.3) are produced. The aryl methyl ethers are successfully cleaved with aluminum triiodide/N,N′-diisopropylcarbodiimide to give a poly(2-oxazoline) with pendent catechol groups.
Mutations in the enzyme isocitrate dehydrogenase 1 (IDH1) lead to metabolic alterations and a sustained formation of 2-hydroxyglutarate (2-HG). 2-HG is an oncometabolite as it inhibits the activity of alpha-ketoglutarate-dependent dioxygenases such as ten-eleven translocation (TET) enzymes. Inhibitors of mutant IDH enzymes, like ML309, are currently tested in order to lower the levels of 2-HG. Vitamin C (VC) is an inducer of TET enzymes. To test a new therapeutic avenue of synergistic effects, the anti-neoplastic activity of inhibition of mutant IDH1 via ML309 in the presence of VC was investigated in the colon cancer cell line HCT116 IDH1(R132H/+) (harbouring a mutated IDH1 allele) and the parental cells HCT116 IDH1(+/+) (wild type IDH1). Measurement of the oncometabolite indicated a 56-fold higher content of 2-HG in mutated cells compared to wild type cells. A significant reduction of 2-HG was observed in mutated cells after treatment with ML 309, whereas VC produced only minimally changes of the oncometabolite. However, combinatorial treatment with both, ML309 and VC, in mutated cells induced pronounced reduction of 2-HG leading to levels comparable to those in wild type cells. The decreased level of 2-HG in mutated cells after combinatorial treatment was accompanied by an enhanced global DNA hydroxymethylation and an increased gene expression of certain tumour suppressors. Moreover, mutated cells showed an increased percentage of apoptotic cells after treatment with non-cytotoxic concentrations of ML309 and VC. These results suggest that combinatorial therapy is of interest for further investigation to rescue TET activity and treatment of IDH1/2 mutated cancers.
Issue Despite their rather similar climatic conditions, eastern Eurasia and northern North America are largely covered by different plant functional types (deciduous or evergreen boreal forest) composed of larch or pine, spruce and fir, respectively. I propose that these deciduous and evergreen boreal forests represent alternative quasi-stable states, triggered by their different northern tree refugia that reflect the different environmental conditions experienced during the Last Glacial. Evidence This view is supported by palaeoecological and environmental evidence. Once established, Asian larch forests are likely to have stabilized through a complex vegetation-fire-permafrost soil-climate feedback system. Conclusion With respect to future forest developments, this implies that Asian larch forests are likely to be governed by long-term trajectories and are therefore largely resistant to natural climate variability on time-scales shorter than millennia. The effects of regional human impact and anthropogenic global warming might, however, cause certain stability thresholds to be crossed, meaning that irreversible transitions occur and resulting in marked consequences for ecosystem services on these human-relevant time-scales.
Salinity stress limits plant growth and has a major impact on agricultural productivity. Here, we identify NAC transcription factor SlTAF1 as a regulator of salt tolerance in cultivated tomato (Solanum lycopersicum).
While overexpression of SlTAF1 improves salinity tolerance compared with wild-type, lowering SlTAF1 expression causes stronger salinity-induced damage. Under salt stress, shoots of SlTAF1 knockdown plants accumulate more toxic Na+ ions, while SlTAF1 overexpressors accumulate less ions, in accordance with an altered expression of the Na+ transporter genes SlHKT1;1 and SlHKT1;2. Furthermore, stomatal conductance and pore area are increased in SlTAF1 knockdown plants during salinity stress, but decreased in SlTAF1 overexpressors.
We identified stress-related transcription factor, abscisic acid metabolism and defence-related genes as potential direct targets of SlTAF1, correlating it with reactive oxygen species scavenging capacity and changes in hormonal response. Salinity-induced changes in tricarboxylic acid cycle intermediates and amino acids are more pronounced in SlTAF1 knockdown than wild-type plants, but less so in SlTAF1 overexpressors. The osmoprotectant proline accumulates more in SlTAF1 overexpressors than knockdown plants.
In summary, SlTAF1 controls the tomato’s response to salinity stress by combating both osmotic stress and ion toxicity, highlighting this gene as a promising candidate for the future breeding of stress-tolerant crops.
Open-circuit voltages of lead-halide perovskite solar cells are improving rapidly and are approaching the thermodynamic limit. Since many different perovskite compositions with different bandgap energies are actively being investigated, it is not straightforward to compare the open-circuit voltages between these devices as long as a consistent method of referencing is missing. For the purpose of comparing open-circuit voltages and identifying outstanding values, it is imperative to use a unique, generally accepted way of calculating the thermodynamic limit, which is currently not the case. Here a meta-analysis of methods to determine the bandgap and a radiative limit for open-circuit voltage is presented. The differences between the methods are analyzed and an easily applicable approach based on the solar cell quantum efficiency as a general reference is proposed.
A thermodynamic study of the adsorption of Human Serum Albumin (HSA) onto spherical polyelectrolyte brushes (SPBs) by isothermal titration calorimetry (ITC) is presented. The SPBs are composed of a solid polystyrene core bearing long chains of poly(acrylic acid). ITC measurements done at different temperatures and ionic strengths lead to a full set of thermodynamicbinding constants together with the enthalpies and entropies of binding. The adsorption of HSA onto SPBs is described with a two-step model. The free energy of binding Delta Gb depends only weakly on temperature because of a marked compensation of enthalpy by entropy. Studies of the adsorbed HSA by Fourier transform infrared spectroscopy (FT-IR) demonstrate no significant disturbance in the secondary structure of the protein. The quantitative analysis demonstrates that counterion release is the major driving force for adsorption in a process where proteins become multivalent counterions of the polyelectrolyte chains upon adsorption. A comparison with the analysis of other sets of data related to the binding of HSA to polyelectrolytes demonstrates that the cancellation of enthalpy and entropy is a general phenomenon that always accompanies the binding of proteins to polyelectrolytes dominated by counterion release.
In this paper, we examine the influence of the 27 October 2012, M-w 7.8 earthquake on landslide occurrence in the southern half of Haida Gwaii (formerly Queen Charlotte Islands), British Columbia, Canada. Our 1350 km(2) study area is undisturbed, primarily forested terrain that has not experienced road building or timber harvesting. Our inventory of landslide polygons is based on optical airborne and spaceborne images acquired between 2007 and 2018, from which we extracted and mapped 446 individual landslides (an average of 33 landslides per 100 km(2)). The landslide rate in years without major earthquakes averages 19.4 per year, or 1.4/100 km(2)/year, and the annual average area covered by non-seismically triggered landslides is 35 ha/year. The number of landslides identified in imagery closely following the 2012 earthquake, and probably triggered by it, is 244 or an average of about 18 landslides per 100 km(2). These landslides cover a total area of 461 ha. In the following years-2013-2016 and 2016-2018-the number of landslides fell, respectively, to 26 and 13.5 landslides per year. In non-earthquake years, most landslides happen on south-facing slopes, facing the prevailing winds. In contrast, during or immediately after the earthquake, up to 32% of the landslides occurred on north and northwest-facing slopes. Although we could not find imagery from the day after the earthquake, overview reconnaissance flights 10 and 16 days later showed that most of the landslides were recent, suggesting they were co-seismic.
Bacteria play key roles in the function and diversity of aquatic systems, but aside from study of specific bloom systems, little is known about the diversity or biogeography of bacteria associated with harmful cyanobacterial blooms (cyanoHABs). CyanoHAB species are known to shape bacterial community composition and to rely on functions provided by the associated bacteria, leading to the hypothesized cyanoHAB interactome, a coevolved community of synergistic and interacting bacteria species, each necessary for the success of the others. Here, we surveyed the microbiome associated with Microcystis aeruginosa during blooms in 12 lakes spanning four continents as an initial test of the hypothesized Microcystis interactome. We predicted that microbiome composition and functional potential would be similar across blooms globally. Our results, as revealed by 16S rRNA sequence similarity, indicate that M. aeruginosa is cosmopolitan in lakes across a 280 degrees longitudinal and 90 degrees latitudinal gradient. The microbiome communities were represented by a wide range of operational taxonomic units and relative abundances. Highly abundant taxa were more related and shared across most sites and did not vary with geographic distance, thus, like Microcystis, revealing no evidence for dispersal limitation. High phylogenetic relatedness, both within and across lakes, indicates that microbiome bacteria with similar functional potential were associated with all blooms. While Microcystis and the microbiome bacteria shared many genes, whole-community metagenomic analysis revealed a suite of biochemical pathways that could be considered complementary. Our results demonstrate a high degree of similarity across global Microcystis blooms, thereby providing initial support for the hypothesized Microcystis interactome.
During the earliest Triassic microbial mats flourished in the photic zones of marginal seas, generating widespread microbialites. It has been suggested that anoxic conditions in shallow marine environments, linked to the end-Permian mass extinction, limited mat-inhibiting metazoans allowing for this microbialite expansion. The presence of a diverse suite of proxies indicating oxygenated shallow sea-water conditions (metazoan fossils, biomarkers and redox proxies) from microbialite successions have, however, challenged the inference of anoxic conditions. Here, the distribution and faunal composition of Griesbachian microbialites from China, Iran, Turkey, Armenia, Slovenia and Hungary are investigated to determine the factors that allowed microbialite-forming microbial mats to flourish following the end-Permian crisis. The results presented here show that Neotethyan microbial buildups record a unique faunal association due to the presence of keratose sponges, while the Palaeotethyan buildups have a higher proportion of molluscs and the foraminifera Earlandia. The distribution of the faunal components within the microbial fabrics suggests that, except for the keratose sponges and some microconchids, most of the metazoans were transported into the microbial framework via wave currents. The presence of both microbialites and metazoan associations were limited to oxygenated settings, suggesting that a factor other than anoxia resulted in a relaxation of ecological constraints following the mass extinction event. It is inferred that the end-Permian mass extinction event decreased the diversity and abundance of metazoans to the point of significantly reducing competition, allowing photosynthesis-based microbial mats to flourish in shallow water settings and resulting in the formation of widespread microbialites.
A facile and novel method for the fabrication of core-shell nanoparticles (PTMA@SiO2) based on a poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) core and a porous SiO2 shell is reported. The core-shell nanoparticles are further self-assembled with negatively charged multi-walled carbon nanotubes (MWCNTs), which results in the formation of a free-standing cathode electrode. The porous SiO2 shell not only effectively improves the stability of the linear PTMA redox polymer with low molar mass in organic electrolytes but also leads to the uniform dispersion of PTMA active units in the MWCNTs conductive network. The PTMA@SiO2@MWCNT composite electrode exhibits a specific capacity as high as 73.8 mAh g at 1 C and only 0.11% capacity loss per cycle at a rate of 2 C.
Sequentially coupling two material functions requires matching the output from the first with the input of the second function. Here, magnetic heating controls thermal actuation of a hybrid composite in a challenging system environment causing an elevated level of heat loss. The concept is a hierarchical design consisting of an inner actuator of nanocomposite material, which can be remotely heated by exposure to an alternating magnetic field (AMF) and outer layers of a porous composite system with a closed pore morphology. These porous layers act as heat insulators and as barriers to the surrounding water. By exposure to the AMF, a local bulk temperature of 71 degrees C enables the magnetic actuation of the device, while the temperature of the surrounding water is kept below 50 degrees C. Interestingly, the heat loss during magnetic heating leads to an increase of the water phase (small volume) temperature. The temperature increase is able to sequentially trigger an adjacent thermal actuator attached to the actuator composite. In this way it could be demonstrated how the AMF is able to initiate two kinds of independent actuations, which might be interesting for robotics operating in aqueous environments.
O caso Jauss
(2019)
The Raman spectra of pure N-2, CO2, and CH4 were analyzed over the range 10 to 500 bars and from -160 degrees C to 200 degrees C (N-2), 22 degrees C to 350 degrees C (CO2), and -100 degrees C to 450 degrees C (CH4). At constant temperature, Raman peak position, including the more intense CO2 peak (nu+), decreases (shifts to lower wave number) with increasing pressure for all three gases over the entire pressure and temperature (PT) range studied. At constant pressure, the peak position for CO2 and CH4 increases (shifts to higher wave number) with increasing temperature over the entire PT range studied. In contrast, N-2 first shows an increase in peak position with increasing temperature at constant pressure, followed by a decrease in peak position with increasing temperature. The inflection temperature at which the trend reverses for N-2 is located between 0 degrees C and 50 degrees C at pressures above similar to 50 bars and is pressure dependent. Below similar to 50 bars, the inflection temperature was observed as low as -120 degrees C. The shifts in Raman peak positions with PT are related to relative density changes, which reflect changes in intermolecular attraction and repulsion. A conceptual model relating the Raman spectral properties of N-2, CO2, and CH4 to relative density (volume) changes and attractive and repulsive forces is presented here. Additionally, reduced temperature-dependent densimeters and barometers are presented for each pure component over the respective PT ranges. The Raman spectral behavior of the pure gases as a function of temperature and pressure is assessed to provide a framework for understanding the behavior of each component in multicomponent N-2-CO2-CH4 gas systems in a future study.
When I took up the task of writing a review of the Routledge handbook of international local government, it occurred to me, as a member of the generation of the 1950s, that I had not even considered whether such compendiums were even necessary in times of easy internet searching. This review will look at whether that is indeed the case.
Social-science handbooks naturally are very broad. This also applies to the particular handbook under review. It comprises six content-thematic parts with 33 chapters by 73 authors from 21 countries, with the UK and USA dominant. The focal points, discussed in more detail below, are local elections and local governance, local governments in different jurisdictions, the challenges of local government services, citizen engagement in local affairs, and local authorities in multi-level finance systems that shape how municipal governments ‘get and spend’ public money. These are exactly the topics actually discussed in the international community of political scientists.
As a preliminary, the editors work out the theoretical-methodological foundations of the topic. They define ‘the local’ as ‘geographically defined sub-national state administrative or political divisions’ (p. 3). As next steps, they analyse the difference between government and governance, and investigate whether local government is globally important and relevant. Fortunately, they conclude that this is indeed the case.
Part I of the handbook illustrates ‘substantive variations’ in the local electoral systems and ‘notable divergences in the values and assumptions of local governance among democratic countries’ (p. 23). That topic is indeed central to local authorities’ legitimacy in democratic political systems. The focus of this part of the handbook is on current research and debates around local electoral systems, the challenges of local political leadership and the councillor’s role in modern local policy. Current trends at the local level are analysed from the actors’ perspectives or from an economic point of view by comparing institutionalised differences in city managers, mayors and council members across different jurisdictions. Sections that investigate traditional leadership and local government in Pacific Island countries are of particular interest to most Western readers, because in Europe and North America we know too little about such issues in that part of the world.
Part II of the handbook presents current development processes and challenges in various local government systems. The chapters are territorially oriented around nation states or sub-national regions. This part of the handbook deal with local government in the Pacific Islands, Latin America, and New Zealand and in the Caribbean. However, the rationale behind country selection is not always clear; important countries like China, India and Nigeria, just to name a few, are absent. Unfortunately, there is no summary article highlighting similarities and differences, as well as the challenges in local government, relating to the countries studied in the book.
The development of local services is the focus of Part III of the handbook, however, the definition of local services remains highly controversial and their scope varies widely between the countries. From the 1980s onwards, there was a long-term trend towards the marketisation and economisation of local politics, but since the turn of the millennium, there has been a counter-trend of the return of municipalities and third sector in the fields of local public services (Wollmann 2018). The book analyses the US and Georgia as case studies for development trends, finding that local government entrepreneurship remains an important factor in promoting economic development and strengthening capacities.
I was pleased to see that Part IV, the next and most extensive part of the handbook, deals with citizen engagement, because the future of local self-government across the world depends not only on top down activities by local governing elites, but above all on the commitment of the inhabitants of cities and municipalities. Practices and challenges of citizen participation in local government are analysed in inspiring case studies of mid-sized cities in Russia and the United States. The contribution on urban governance of austerity in Europe is also of particular interest. The 2008 global financial crash and the subsequent severe budgetary pressure on municipalities in many countries was a key event in the history and development of local self-government, confronting municipalities with ‘the harsh realities of political economy’ (p. 293). Several articles analyse the causes of the declining confidence of the citizens in local authorities in some countries. In contrast, the open budget tool in Brazil is as a positive example of collaborative stakeholder engagement.
Part V deals with multi-level governance. With the exception of Australia, it is all about Europe, especially the role of municipalities in the EU’s multilevel system. The authors conclude that ‘local authorities are essential for executing EU legislation, and this turn allows them to shape EU policies’ (p. 401). This part of the handbook includes the issue of local territorial reforms, which are central to local autonomy, combined with analyses of redesigning regional government and local-level Europeanisation. Subsequently, by comparing the local government systems of Southern Europe (France, Italy, Portugal and Spain), the authors underline convincingly the role of traditions, identity, legal frameworks and institutions in local government.
Part VI of the book deals with the financial dimension of local self-government under the heading ‘Getting and spending’. This is indeed the ‘key source of dispute between local and central government’ (p. 467) and the crucial factor shaping true local autonomy. Meritoriously, this part also contains a chapter on the fight against corruption and unethical behaviour by public servants. Based on research linking corruption to transparency and accountability, two case studies describe how Tbilisi (Georgia) and Lviv (Ukraine) try to reduce corruption in government budgeting and procurement. Enhancing Value-For-Money audit in local government highlights another important side of local finance. An interesting comparison reveals significant differences in local government revenues in European Union member states between 2000 and 2014.
Of course, even in a 530-page book, some important aspects remain underexposed. Above all, I would have liked more attention on some of the enormous future challenges facing democratic systems and with them local governments all over the world, such as digitisation (e.g. in smart cities), the integration of migrants or climate change. The international networking of municipalities should also be given greater prominence.
To sum it up, The Routledge Handbook on International Local Government is indeed ‘ambitiously titled’ as the editors underline. Yet, despite my critical objections about its focus on current issues rather than future challenges, they largely fulfil this promise and their general approach has worked well. Across continents and political-administrative cultures, illustrated with many new research findings, they have created an outstanding publication focusing on the challenges and policy of local self-governmental authorities and other local stakeholders. There is a good chance that this handbook will belong in future to the social science standard works on local issues, and be included in academic political science teaching. May the publisher’s wish come true; that this book stimulates its readers to develop further research ideas.
Finally, I come back to my initial question. ‘Old fashioned’ printed handbooks like these continue to make sense, even in modern digital times.
Microbial communities are essential components of aquatic ecosystems through their contribution to food web dynamics and biogeochemical processes. Aquatic microbial diversity is immense and a general challenge is to understand how metabolism and interactions of single organisms shape microbial community dynamics and ecosystem-scale biogeochemical transformations. Metagenomic approaches have developed rapidly, and proven to be powerful in linking microbial community dynamics to biogeochemical processes. In this review, we provide an overview of metagenomic approaches, followed by a discussion on some recent insights they have provided, including those in this special issue. These include the discovery of new taxa and metabolisms in aquatic microbiomes, insights into community assembly and functional ecology as well as evolutionary processes shaping microbial genomes and microbiomes, and the influence of human activities on aquatic microbiomes. Given that metagenomics can now be considered a mature technology where data generation and descriptive analyses are relatively routine and informative, we then discuss metagenomic-enabled research avenues to further link microbial dynamics to biogeochemical processes. These include the integration of metagenomics into well-designed ecological experiments, the use of metagenomics to inform and validate metabolic and biogeochemical models, and the pressing need for ecologically relevant model organisms and simple microbial systems to better interpret the taxonomic and functional information integrated in metagenomes. These research avenues will contribute to a more mechanistic and predictive understanding of links between microbial dynamics and biogeochemical cycles. Owing to rapid climate change and human impacts on aquatic ecosystems, the urgency of such an understanding has never been greater.
The impact of the orientation of zwitterionic groups, with respect to the polymer backbone, on the antifouling performance of thin hydrogel films made of polyzwitterions is explored. In an extension of the recent discussion about differences in the behavior of polymeric phosphatidylcholines and choline phosphates, a quasi-isomeric set of three poly(sulfobetaine methacrylate)s is designed for this purpose. The design is based on the established monomer 3-[N-2-(methacryloyloxy)ethyl-N,N-dimethyl]ammonio-propane-1-sulfonate and two novel sulfobetaine methacrylates, in which the positions of the cationic and the ionic groups relative to the polymerizable group, and thus also to the polymer backbone, are altered. The effect of the varied segmental dipole orientation on their water solubility, wetting behavior by water, and fouling resistance is compared. As model systems, the adsorption of the model proteins bovine serum albumin (BSA), fibrinogen, and lysozyme onto films of the various polyzwitterion surfaces is studied, as well as the settlement of a diatom (Navicula perminuta) and barnacle cyprids (Balanus improvisus) as representatives of typical marine fouling communities. The results demonstrate the important role of the zwitterionic group's orientation on the polymer behavior and fouling resistance.
Shrub encroachment has far-reaching ecological and economic consequences in many ecosystems worldwide. Yet, compositional changes associated with shrub encroachment are often overlooked despite having important effects on ecosystem functioning. We document the compositional change and potential drivers for a northern Namibian Combretum woodland transitioning into a Terminalia shrubland. We use a multiproxy record (pollen, sedimentary ancient DNA, biomarkers, compound-specific carbon (delta C-13) and deuterium (delta D) isotopes, bulk carbon isotopes (delta(13)Corg), grain size, geochemical properties) from Lake Otjikoto at high taxonomical and temporal resolution. We provide evidence that state changes in semiarid environments may occur on a scale of one century and that transitions between stable states can span around 80 years and are characterized by a unique vegetation composition. We demonstrate that the current grass/woody ratio is exceptional for the last 170 years, as supported by n-alkane distributions and the delta C-13 and delta(13)Corg records. Comparing vegetation records to environmental proxy data and census data, we infer a complex network of global and local drivers of vegetation change. While our delta D record suggests physiological adaptations of woody species to higher atmospheric pCO(2) concentration and drought, our vegetation records reflect the impact of broad-scale logging for the mining industry, and the macrocharcoal record suggests a decrease in fire activity associated with the intensification of farming. Impact of selective grazing is reflected by changes in abundance and taxonomical composition of grasses and by an increase of nonpalatable and trampling-resistant taxa. In addition, grain-size and spore records suggest changes in the erodibility of soils because of reduced grass cover. Synthesis. We conclude that transitions to an encroached savanna state are supported by gradual environmental changes induced by management strategies, which affected the resilience of savanna ecosystems. In addition, feedback mechanisms that reflect the interplay between management legacies and climate change maintain the encroached state.
Letter knowledge is considered an important cognitive foundation for learning to read. The underlying mechanisms of the association between letter knowledge and reading skills are, however, not fully understood. Acquiring letter knowledge depends on the ability to learn and retrieve sound–symbol pairings. In the current study, this process was explored by setting preschool children’s (N = 242, mean age = 5.57 years) performance in the acquisition and retrieval of a paired associate learning (PAL) task in relation to their letter knowledge as well as to their performance in tasks assessing precursors of reading skills (i.e., phonological awareness, rapid automatized naming, phonological short-term memory, backward recall, and response inhibition). Multiple regression analyses revealed that performance in the acquisition of the PAL task was significantly associated with phonological awareness and backward recall, whereas performance in the retrieval of the PAL task was significantly associated with rapid automatized naming, phonological awareness, and backward recall. Moreover, PAL proved to be mediating the relation between reading precursors and letter knowledge. Together, these findings indicate that the acquisition of letter knowledge may depend on a visual–verbal associative learning mechanism and that different factors contribute to the acquisition and retrieval of such visual–verbal associations.
Pollen/ovule (P/O) ratios are often used as proxy for breeding systems. Here, we investigate the relations between breeding systems and P/O ratios, pollination syndromes, life history and climate zone in Balsaminaceae. We conducted controlled breeding system experiments (autonomous and active self-pollination and outcrossing tests) for 65 Balsaminaceae species, analysed pollen grain and ovule numbers and evaluated the results in combination with data on pollination syndrome, life history and climate zone on a phylogenetic basis. Based on fruit set, we assigned three breeding systems: autogamy, self-compatibility and self-incompatibility. Self-pollination led to lower fruit set than outcrossing. We neither found significant P/O differences between breeding systems nor between pollination syndromes. However, the numbers of pollen grains and ovules per flower were significantly lower in autogamous species, but pollen grain and ovule numbers did not differ between most pollination syndromes. Finally, we found no relation between breeding system and climate zone, but a relation between climate zone and life history. In Balsaminaceae reproductive traits can change under resource or pollinator limitation, leading to the evolution of autogamy, but are evolutionary rather constant and not under strong selection pressure by pollinator guild and geographic range changes. Colonisation of temperate regions, however, is correlated with transitions towards annual life history. Pollen/ovule-ratios, commonly accepted as good indicators of breeding system, have a low predictive value in Balsaminaceae. In the absence of experimental data on breeding system, additional floral traits (overall pollen grain and ovule number, traits of floral morphology) may be used as proxies.
The thermal structure of subduction zones exerts a major influence on deep-seated mechanical and chemical processes controlling arc magmatism, seismicity, and global element cycles. Accretionary complexes exposed inland may comprise tectonic blocks with contrasting pressure-temperature (P-T) histories, making it possible to investigate the dynamics and thermal evolution of former subduction interfaces. With this aim, we present new Lu-Hf geochronological results for mafic rocks of the Halilbagi Complex (Anatolia) that evolved along different thermal gradients. Samples include a lawsonite-epidote blueschist, a lawsonite-epidote eclogite, and an epidote eclogite (all with counter-clockwise P-T paths), a prograde lawsonite blueschist with a "hairpin"-type P-T path, and a garnet amphibolite from the overlying sub-ophiolitic metamorphic sole. Equilibrium phase diagrams suggest that the garnet amphibolite formed at similar to 0.6-0.7 GPa and 800-850 degrees C, whereas the prograde lawsonite blueschist records burial from 2.1 GPa and 420 degrees C to 2.6 GPa and 520 degrees C. Well-defined Lu-Hf isochrons were obtained for the epidote eclogite (92.38 +/- 0.22 Ma) and the lawsonite-epidote blueschist (90.19 +/- 0.54 Ma), suggesting rapid garnet growth. The lawsonite-epidote eclogite (87.30 +/- 0.39 Ma) and the prograde lawsonite blueschist (ca. 86 Ma) are younger, whereas the garnet amphibolite (104.5 +/- 3.5 Ma) is older. Our data reveal a consistent trend of progressively decreasing geothermal gradient from granulite-facies conditions at similar to 104 Ma to the epidote-eclogite facies around 92 Ma, and the lawsonite blueschist-facies between 90 Ma and 86 Ma. Three Lu-Hf garnet dates (between 92 Ma and 87 Ma) weighted toward the growth of post-peak rims (as indicated by Lu distribution in garnet) suggest that the HP/LT rocks were exhumed continuously and not episodically. We infer that HP/LT metamorphic rocks within the Halilbagi Complex were subjected to continuous return flow, with "warm" rocks being exhumed during the tectonic burial of "cold" ones. Our results, combined with regional geological constraints, allow us to speculate that subduction started at a transform fault near a mid-oceanic spreading centre. Following its formation, this ancient subduction interface evolved thermally over more than 15 Myr, most likely as a result of heat dissipation rather than crustal underplating. (C) 2018, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V.
This is a correction notice for ‘Post-adiabatic supernova remnants in an interstellar magnetic field: oblique shocks and non-uniform environment’ (DOI: https://doi.org/10.1093/mnras/sty1750), which was published in MNRAS 479, 4253–4270 (2018). The publisher regrets to inform that the colour was missing from the colour scales in Figs 8(a)–(d) and Figs 9(a) and (b). This has now been corrected online. The publisher apologizes for this error.
One of the biggest successes of the Cassini mission is the detection of small moons (moonlets) embedded in Saturns rings that cause S-shaped density structures in their close vicinity, called propellers. Here, we present isothermal hydrodynamic simulations of moonlet-induced propellers in Saturn's A ring that denote a further development of the original model. We find excellent agreement between these new hydrodynamic and corresponding N-body simulations. Furthermore, the hydrodynamic simulations confirm the predicted scaling laws and the analytical solution for the density in the propeller gaps. Finally, this mean field approach allows us to simulate the pattern of the giant propeller Blériot, which is too large to be modeled by direct N-body simulations. Our results are compared to two stellar occultation observations by the Cassini Ultraviolet Imaging Spectrometer (UVIS), which intersect the propeller Blériot. Best fits to the UVIS optical depth profiles are achieved for a Hill radius of 590 m, which implies a moonlet diameter of about 860 m. Furthermore, the model favors a kinematic shear viscosity of the surrounding ring material of ν0 = 340 cm2 s−1, a dispersion velocity in the range of 0.3 cm s−1 < c0 < 1.5 cm s−1, and a fairly high bulk viscosity 7 < ξ0/ν0 < 17. These large transport values might be overestimated by our isothermal ring model and should be reviewed by an extended model including thermal fluctuations.
Insulin-Like Growth Factor Binding Protein 2 (IGFBP-2) and the Risk of Developing Type 2 Diabetes
(2019)
Recent studies suggest that insulin-like growth factor binding protein 2 (IGFBP-2) may protect against type 2 diabetes, but population-based human studies are scarce. We aimed to investigate the prospective association of circulating IGFBP-2 concentrations and of differential methylation in the IGFBP-2 gene with type 2 diabetes risk.
Specialisation and diversity of multiple trophic groups are promoted by different forest features
(2019)
While forest management strongly influences biodiversity, it remains unclear how the structural and compositional changes caused by management affect different community dimensions (e.g. richness, specialisation, abundance or completeness) and how this differs between taxa. We assessed the effects of nine forest features (representing stand structure, heterogeneity and tree composition) on thirteen above- and belowground trophic groups of plants, animals, fungi and bacteria in 150 temperate forest plots differing in their management type. Canopy cover decreased light resources, which increased community specialisation but reduced overall diversity and abundance. Features increasing resource types and diversifying microhabitats (admixing of oaks and conifers) were important and mostly affected richness. Belowground groups responded differently to those aboveground and had weaker responses to most forest features. Our results show that we need to consider forest features rather than broad management types and highlight the importance of considering several groups and community dimensions to better inform conservation.
Metabolic networks play a crucial role in biology since they capture all chemical reactions in an organism. While there are networks of high quality for many model organisms, networks for less studied organisms are often of poor quality and suffer from incompleteness. To this end, we introduced in previous work an answer set programming (ASP)-based approach to metabolic network completion. Although this qualitative approach allows for restoring moderately degraded networks, it fails to restore highly degraded ones. This is because it ignores quantitative constraints capturing reaction rates. To address this problem, we propose a hybrid approach to metabolic network completion that integrates our qualitative ASP approach with quantitative means for capturing reaction rates. We begin by formally reconciling existing stoichiometric and topological approaches to network completion in a unified formalism. With it, we develop a hybrid ASP encoding and rely upon the theory reasoning capacities of the ASP system dingo for solving the resulting logic program with linear constraints over reals. We empirically evaluate our approach by means of the metabolic network of Escherichia coli. Our analysis shows that our novel approach yields greatly superior results than obtainable from purely qualitative or quantitative approaches.
Dipeptidyl peptidase 4 (DPP4) is known to be elevated in metabolic disturbances such as obesity, type 2 diabetes and fatty liver disease. Lowering DPP4 concentration by pharmacological inhibition improves glucose homeostasis and exhibits beneficial effects to reduce hepatic fat content. As factors regulating the endogenous expression of Dpp4 are unknown, the aim of this study was to examine whether the Dpp4 expression is epigenetically regulated in response to dietary components. Primary hepatocytes were treated with different macronutrients, and Dpp4 mRNA levels and DPP4 activity were evaluated. Moreover, dietary low-protein intervention was conducted in New Zealand obese (NZO) mice, and subsequently, effects on Dpp4 expression, methylation as well as plasma concentration and activity were determined. Our results indicate that Dpp4 mRNA expression is mediated by DNA methylation in several tissues. We therefore consider the Dpp4 southern shore as tissue differentially methylated region. Amino acids increased Dpp4 expression in primary hepatocytes, whereas glucose and fatty acids were without effect. Dietary protein restriction in NZO mice increased Dpp4 DNA methylation in liver leading to diminished Dpp4 expression and consequently to lowered plasma DPP4 activity. We conclude that protein restriction in the adolescent and adult states is a sufficient strategy to reduce DPP4 which in turn contributes to improve glucose homeostasis. (C) 2018 Published by Elsevier Inc.
Lyman limit systems (LLSs) trace the low-density circumgalactic medium and the most dense regions of the intergalactic medium, so their number density and evolution at high-redshift, just after reionization, are important to constrain. We present a survey for LLSs at high redshifts, z(LLS) = 3.5-5.4, in the homogeneous data set of 153 optical quasar spectra at z similar to 5 from the Giant Gemini GMOS survey. Our analysis includes detailed investigation of survey biases using mock spectra which provide important corrections to the raw measurements. We estimate the incidence of LLSs per unit redshift at z approximate to 4.4 to be l(z) = 2.6 +/- 0.4. Combining our results with previous surveys at z(LLS) < 4, the best-fit power-law evolution is l(z) = l(*)[(1 + z)/4](alpha) with l* = 1.46 +/- 0.11 and alpha = 1.70 +/- 0.22 (68 per cent confidence intervals). Despite hints in previous z(LLS) < 4 results, there is no indication for a deviation from this single power-law soon after reionization. Finally, we integrate our new results with previous surveys of the intergalactic and circumgalactic media to constrain the hydrogen column density distribution function, f(N-HI, X), over 10 orders ofmagnitude. The data at z similar to 5 are not well-described by the f(N-HI, X) model previously reported for z similar to 2-3 (after re-scaling) and a 7-pivot model fitting the full z similar to 2-5 data set is statistically unacceptable. We conclude that there is significant evolution in the shape of f(N-HI, X) over this similar to 2-billion-year period.
Fire and grazing shape biodiversity in savannah landscapes. In land use management, knowing the effects of fire and grazing on biodiversity are important in order to ensure environmental sustainability. Beetles specifically are indicators of the biodiversity response to fire and grazing. A grazing exclusion and burning experiment in a split-plot design was used in order to investigate the interacting effects of fire and wildlife grazing on biomass, diversity, and species composition of darkling beetles (Coleoptera, Tenebrionidae) over time after fire. Darkling beetle species richness and diversity were responding in a three-way-interaction to fire, grazing, and time after fire, whereby biomass of darkling beetles remained unaffected and species compositional changes were attributed to seasonal changes of time only. Fire on ungrazed plots had a negative effect on species diversity and richness 2 weeks and 6 months post fire, whereas fire on grazed plots had no impact on species diversity and richness. Grazing only lowered species diversity and richness 6 months after fire treatments. Results suggest that grazing overrides the effects of fire and that the similar effects caused by fire and grazing are due to niche and assemblage simplification of the habitat.
Parasites, such as bacterial viruses (phages), can have large effects on host populations both at the ecological and evolutionary levels. In the case of cyanobacteria, phages can reduce primary production and infected hosts release intracellular nutrients influencing planktonic food web structure, community dynamics, and biogeochemical cycles. Cyanophages may be of great importance in aquatic food webs during large cyanobacterial blooms unless the host population becomes resistant to phage infection. The consequences on plankton community dynamics of the evolution of phage resistance in bloom forming cyanobacterial populations are still poorly studied. Here, we examined the effect of different frequencies of a phage-resistant genotype within a filamentous nitrogen-fixing Nodularia spumigena population on an experimental plankton community. Three Nodularia populations with different initial frequencies (0%, 5%, and 50%) of phage-resistant genotypes were inoculated in separate treatments with the phage 2AV2, the green alga Chlorella vulgaris, and the rotifer Brachionus plicatilis, which formed the experimental plankton community subjected to either nitrogen-limited or nitrogen-rich conditions. We found that the frequency of the phage-resistant Nodularia genotype determined experimental community dynamics. Cyanobacterial populations with a high frequency (50%) of the phage-resistant genotype dominated the cultures despite the presence of phages, retaining most of the intracellular nitrogen in the plankton community. In contrast, populations with low frequencies (0% and 5%) of the phage-resistant genotype were lysed and reduced to extinction by the phage, transferring the intracellular nitrogen held by Nodularia to Chlorella and rotifers, and allowing Chlorella to dominate the communities and rotifers to survive. This study shows that even though phages represent minuscule biomass, they can have key effects on community composition and eco-evolutionary feedbacks in plankton communities.