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A pesar de que Chile no estuvo incluido en el viaje sudamericano de Alejandro de Humboldt, dada la preferencia del naturalista prusiano por escenario tropical, su presencia se hizo evidente durante el siglo XIX. Aquí, en particular, se analiza lo anterior a partir de dos esferas: la figura de Alejandro de Humboldt y la ciencia humboldtiana en Chile. Por un lado, se analizan las formas de apropiación que la ciencia hizo de la obra de Humboldt durante el siglo XIX. En otro aspecto, se analiza a Alejandro de Humboldt como esfera de legitimación para la propia intelectualidad chilena decimonónica. Desde esta perspectiva se comentan las formas a partir de las cuales el nombre del autor berlinés fue instalado en las discusiones y circuitos ilustrados chilenos.
Im Zusammenhang mit einer geplanten Wiederveröffentlichung des Bandes Die Jugendbriefe Alexander von Humboldts 1787-1799 durch den Akademie Verlages im Andenken an die kürzlich verstorbene Mitherausgeberin Ilse Jahn sollen in loser Folge bisher unpublizierte Briefe aus der Jugendzeit Alexander von Humboldts in der Rubrik Von Humboldts Hand erscheinen. Der folgende Brief Alexander von Humboldts an den Göttinger Arzt Christoph Girtanner steht am Anfang dieser Reihe, welche sukzessive versucht, neuere Erkenntnisse der Alexander-von-Humboldt-Forschungsstelle in Bezug auf die Jugendbriefe zu publizieren. Das Schreiben, welches zur so genannten Berlinka-Sammlung der Biblioteka Jagiellońska in Krakau gehört, gelangte während des Zweiten Weltkrieges nach Polen, und ist der Forschungsstelle vor einiger Zeit zugänglich gemacht worden. Editorisch werden sich die in dieser Rubrik erscheinenden Briefe Humboldts in den bestehenden Band der Jugendbriefe von 1973 einfügen.
Der Vergleich mit Humboldts Tagebüchern bietet Aufschlüsse über die für Humboldt typische Arbeitsweise und die Wege seines Wissenserwerbs. Seine eigenen Beobachtungen während des Aufenthaltes in Mexiko sind ergänzt durch persönliche Kontakte vor Ort, durch Literatur- und Archivstudien in Mexiko und nach der Rückkehr in europäischen Archiven. So hat er beispielsweise die Pyramiden von Teotihuacan nicht besucht, aber die Beschreibung aus einem Brief von Juan José de Oteyza, den er am Real Seminario de Minería in Mexiko-Stadt kennengelernt hatte, in seine Publikation aufgenommen. Auch einzelne Tafeln stellen mexikanische Altertümer dar, die Humboldt nicht selbst besichtigt hat. Im Vortrag werden einige Quellen der „Vues des Cordillères“ aus Humboldts Tagebüchern vorgestellt, wie z. B. Beschreibungen seiner Exkursionen in Mexiko aus den von der Alexander-von-Humboldt-Forschungsstelle publizierten Bänden und bisher unedierte Notizen seiner Studien im Archiv des Vatikans im Sommer 1805.
Über die Autoren
(2010)
Über die Autoren
(2010)
Zwischen Thron und Ballotage
(2010)
Bei einer aktuellen Studie am Iberg in Bad Grund konnten im September 2010 acht Fledermausarten parasitologisch untersucht werden. Die Faenge ergaben Nachweise von 11 Ektoparasitenarten (Fledermausfliegen, Floehe, Flughaut- und Ohrmilben), wobei einige davon Erstfunde fuer Niedersachsen sind. Aus den Fundangaben wurden Parasitenspektren fuer die einzelnen Wirtsarten erstellt und durch weitere unveroeffentlichte Meldungen ergaenzt. Fuer den Vergleich von Ektoparasitenspektren verschiedener Wirtsarten erfolgte die Einfuehrung einer Formel, die die Berechnung einer allgemeinen "Parasitenlast" ermoeglicht. Die Betrachtung der Verteilung von Ektoparasiten auf Individuen zeigte eine starke Trennung verschiedener Parasitengruppen, ein synchrones Vorkommen wurde nur selten registriert. Moeglicherweise ist die Konkurrenz zwischen Ektoparasitenarten ein bisher unterschaetzter determinierender Faktor fuer die Praesenz auf einem Wirt.
Following up on an exchange about the relation between microsaccades and spatial attention (Horowitz, Fencsik, Fine, Yurgenson, & Wolfe, 2007; Horowitz, Fine, Fencsik, Yurgenson, & Wolfe, 2007; Laubrock, Engbert, Rolfs, & Kliegl, 2007), we examine the effects of selection criteria and response modality. We show that for Posner cuing with saccadic responses, microsaccades go with attention in at least 75% of cases (almost 90% if probability matching is assumed) when they are first (or only) microsaccades in the cue target interval and when they occur between 200 and 400 msec after the cue. The relation between spatial attention and the direction of microsaccades drops to chance level for unselected microsaccades collected during manual-response conditions. Analyses of data from four cross-modal cuing experiments demonstrate an above-chance, intermediate link for visual cues, but no systematic relation for auditory cues. Thus, the link between spatial attention and direction of microsaccades depends on the experimental condition and time of occurrence, but it can be very strong.
Two recent studies (Johnson et al., 2005; Perez-Leroux, 2006) found that English- and Spanish-learning children do not show the ability to use verb inflection as a cue to subject number before the age of 5 to 6 years. These findings suggest an asymmetric development as verb inflections are usually correctly produced before this age. In the present study we investigated whether German 3- to 4-year-olds take advantage of the information provided by the verb inflection in sentence comprehension. In a first study, children's looking behavior at two pictures was measured after presentation of a sentence in which the subject number was coded only by the verb inflection. The results from this study suggest that children's looks reflect correct interpretation of the sentences and thus show their ability to make use of verb inflection. In a second experiment, preferential looking was combined with an additional task in which the children had to point to the matching picture. in this case children did not perform above chance level. Our results underline the relevance that specific task demands have on the performance of children in comprehension testing. These have to be accounted for when interpreting findings on production and comprehension asymmetries in language acquisition.
Wer sagt, was Leben ist? : Perspektiven der Debatte um eine lebenswissenschaftliche Philologie
(2010)
Homopolymers of N-acryloyl glycinamide were prepared by reversible addition-fragmentation chain transfer polymerization in water. The formed macromolecules exhibit strong polymer-polymer interactions in aqueous milieu and therefore form thermoreversible physical hydrogels in pure water, physiological buffer or cell medium.
WIP proteins form a plant specific subfamily of C2H2 zinc finger (ZF) proteins. In this study, we functionally characterized the WIP domain, which consists of four ZF motifs, and discuss molecular functions for WIP proteins. Mutations in each of the ZFs lead to loss of function of the TT1/WIP1 protein in Arabiopsis thaliana. SV40 type nuclear localisation signals were detected in two of the ZFs and functionally characterized using GFP fusions as well as new mutant alleles identified by TILLING. Promoter swap experiments showed that selected WIP proteins are partially able to take over TT1 function. Activity of the AtBAN promoter, a potential TT1 target, could be increased by the addition of TT1 to the TT2-TT8-TTG1 regulatory complex.
We consider a solution of the nonlinear Klein-Gordon equation perturbed by a parametric driver. The frequency of parametric perturbation varies slowly and passes through a resonant value, which leads to a solution change. We obtain a new connection formula for the asymptotic solution before and after the resonance.
Was ist eine kreative Leistung von Studierenden? Dies ist die Ausgangsfrage, wenn Lehre kreativitätsförderlicher als bislang gestaltet werden soll. In diesem Beitrag wird ein Modell zur Förderung von Kreativität in der Hochschullehre vorgestellt und mit einem Beispiel verdeutlicht. Es wird die veränderte Konzeption der Vorlesung Informatik & Gesellschaft illustriert: Studierende hatten die Aufgabe, eine „e-Infrastruktur für die Universität NeuDoBoDu“ zu entwickeln. Hierzu werden die Ergebnisse der Evaluation und Erfahrungen erläutert.
Warum vertragen anders ist als vergiften und vergessen : ein Einblick in unser mentales Lexikon
(2010)
Vorwort
(2010)
Die Studienanfänger der Informatik haben in Deutschland sehr unterschiedliche Grundkenntnisse in der Programmierung. Dies führt immer wieder zu Schwierigkeiten in der Ausrichtung der Einführungsveranstaltungen. An der TU München wird seit dem Wintersemester 2008/2009 nun eine neue Art von Vorkursen angeboten. In nur 2,5 Tagen erstellen die Teilnehmer ein kleines objektorientiertes Programm. Dabei arbeiten sie weitestgehend alleine, unterstützt von einem studentischen Tutor. In dieser Arbeit sollen nun das Konzept der sogenannten „Vorprojekte“ sowie erste Forschungsansätze vorgestellt werden
I. Genehmigungsregelungen im Kontext der Auseinandersetzungen um die Dienstleistungsrichtlinie II. Begriffliche Grundlagen II. 1. Genehmigungsbegriff II. 2. Abgrenzung von Niederlassungs- und Dienstleistungsfreiheit III. Anforderungen an Genehmigungen im Rahmen der Niederlassungsfreiheit III. 1. Anforderungen an Genehmigungsregelungen (Art. 9 DLRL) III. 2. Voraussetzungen für die Erteilung der Genehmigung (Art. 10 DLRL) III. 3. Genehmigungsdauer (Art. 11 DLRL) III. 4. Beschränkungen der Anzahl der Genehmigungen (Art. 12 DLRL) III. 5. Genehmigungsverfahren (Art. 13 DLRL) IV. Anforderungen an Tätigkeiten im Rahmen des freien Dienstleistungsverkehrs V. Zusammenfassung und Bewertung
Entanglement entropy obeys area law scaling for typical physical quantum systems. This may naively be argued to follow from the locality of interactions. We show that this is not the case by constructing an explicit simple spin chain Hamiltonian with nearest-neighbor interactions that presents an entanglement volume scaling law. This non- translational model is contrived to have couplings that force the accumulation of singlet bonds across the half-chain. This configuration of the couplings is suggested by real-space renormalization group arguments. Computation of the entanglement entropy is performed by mapping the system to free fermions and diagonalizing numerically its correlation matrix. An analytical relationship between the entanglement entropy and the Frobenius norm of the correlation matrix is also established. Our result is complementary to the known relationship between non-translational invariant, nearest- neighbor interacting Hamiltonians and quantum Merlin-Arthur (QMA)complete problems.
Dialysis patients experience an excess mortality, predominantly of sudden cardiac death (SCD). Accumulating evidence suggests a role of vitamin D for myocardial and overall health. This study investigated the impact of vitamin D status on cardiovascular outcomes and fatal infections in haemodialysis patients. 25-hydroxyvitamin D [25(OH)D] was measured in 1108 diabetic haemodialysis patients who participated in the German Diabetes and Dialysis Study and were followed up for a median of 4 years. By Cox regression analyses, we determined hazard ratios (HR) for pre-specified, adjudicated endpoints according to baseline 25(OH)D levels: SCD (n = 146), myocardial infarction (MI, n = 174), stroke (n = 89), cardiovascular events (CVE, n = 414), death due to heart failure (n = 37), fatal infection (n = 111), and all- cause mortality (n = 545). Patients had a mean age of 66 +/- 8 years (54% male) and median 25(OH)D of 39 nmol/L (interquartile range: 28-55). Patients with severe vitamin D deficiency [25(OH)D of < 25 nmol/L] had a 3-fold higher risk of SCD compared with those with sufficient 25(OH)D levels > 75 nmol/L [HR: 2.99, 95% confidence interval (CI): 1.39- 6.40]. Furthermore, CVE and all-cause mortality were strongly increased (HR: 1.78, 95% CI: 1.18-2.69, and HR: 1.74, 95% CI: 1.22-2.47, respectively), all persisting in multivariate models. There were borderline non-significant associations with stroke and fatal infection while MI and deaths due to heart failure were not meaningfully affected. Severe vitamin D deficiency was strongly associated with SCD, CVE, and mortality, and there were borderline associations with stroke and fatal infection. Whether vitamin D supplementation decreases adverse outcomes requires further evaluation.
Victorian Women Artists
(2010)
African savannas are primarily used as pastures and are subject to changes in climate and management strategies. For sustainable management of these landscapes ecological knowledge on seasonal and long-term variability in plant community composition and the availability of green biomass is essential. In this study, we assessed the effects of dry and wet season on species richness and beta diversity for three sites along a gradient of increasing vegetation cover and precipitation in northwest Namibia. A hexagonal systematic sampling design was used to record floristic data. The Simple Matching, Soerensen, and multi-plot similarity coefficient and distance decay analyses were applied for examining beta diversity. Analyses were repeated while separating the plots according to the presence of woody vegetation. Species richness nearly doubled from dry to wet season; compositional similarity increased from dry to wet season and with increasing aridity of the study sites: distance decay was more pronounced in the dry season without any link to the precipitation gradient. Woody elements in the landscape, which occur along drainage lines or as tree islands, govern spatial and seasonal plant diversity fluctuations. Monitoring them is important for conservation strategies and for establishing grazing rules that ensure a sustainable use of savanna ecosystems.
In this paper we introduce and study some new cooperation protocols for cooperating distributed (CD) grammar systems. These derivation modes depend on the number of different nonterminals present in the sentential form obtained when a component finished a derivation phase. This measure describes the competence of the grammar on the string (the competence is high if the number of the different nonterminals is small). It is also a measure of the efficiency of the grammar on the given string (a component is more efficient than another one if it is able to decrease the number of nonterminals in the string to a greater extent). We prove that if the underlying derivation mode is the t-mode derivation, then some variants of these systems determine the class of random context ET0L languages. If these CD grammar systems use the k step limited derivations as underlying derivation mode, then they are able to generate any recursively enumerable language.
The apparent isotope enrichment factor epsilon(macrophyte) of submerged plants (epsilon(macrophyte-DIC) = delta C-13(macrophyte) - delta C-13(DIC)) is indicative of dissolved inorganic carbon (DIC) supply in neutral to alkaline waters and is related to variations in aquatic productivity (Papadimitriou et al. in Limnol Oceanogr 50:1084-1095, 2005). This paper aims to evaluate the usage of epsilon(macrophyte) inferred from isotopic analyses of submerged plant fossils in addition to analyses of lake carbonate as a palaeolimnological proxy for former HCO3 (-) concentrations. Stable carbon isotopic analysis of modern Potamogeton pectinatus leaves and its host water DIC from the Tibetan Plateau and Central Yakutia (Russia) yielded values between -23.3 and +0.4aEuro degrees and between +14.0 and +6.5aEuro degrees, respectively. Values of epsilon (Potamogeton-DIC) (range -15.4 to +1.1aEuro degrees) from these lakes are significantly correlated with host water HCO3 (-) concentration (range 78-2,200 mg/l) (r = -0.86; P < 0.001), thus allowing for the development of a transfer function. Palaeo-epsilon (Potamogeton-ostracods) values from Luanhaizi Lake on the NE Tibetan Plateau, as inferred from the stable carbon isotope measurement of fossil Potamogeton pectinatus seeds (range -24 to +2.8aEuro degrees) and ostracods (range -7.8 to +7.5%) range between -14.8 and 1.6aEuro degrees. Phases of assumed disequilibrium between delta C-13(DIC) and delta C-13(ostracods) known to occur in charophyte swards (as indicated by the deposition of charophyte fossils) were excluded from the analysis of palaeo-epsilon. The application of the epsilon (Potamogeton-DIC)-HCO3 (-) transfer function yielded a median palaeo-HCO3 (-) -concentration of 290 mg/l. Variations in the dissolved organic carbon supply compare well with aquatic plant productivity changes and lake level variability as inferred from a multiproxy study of the same record including analyses of plant macrofossils, ostracods, carbonate and organic content.
One-way measurement based quantum computations (1WQC) may describe unitary transformations, via a composition of CPTP maps which are not all unitary themselves. This motivates the following decision problems. Is it possible to determine whether a "quantum-to-quantum" 1WQC procedure (having non-trivial input and output subsystems) performs a unitary transformation? Is it possible to describe precisely how such computations transform quantum states, by translation to a quantum circuit of comparable complexity? In this article, we present an efficient algorithm for transforming certain families of measurement-based computations into a reasonable unitary circuit model, in particular without employing the principle of deferred measurement.
We experimentally demonstrate efficient switching of the hard x-ray Bragg reflectivity of a SrRuO3 /SrTiO3 superlattice by optical excitation of large-amplitude coherent acoustic superlattice phonons. The rocking curve changes drastically on a 1 ps timescale. The (0 0 116) reflection is almost extinguished (Delta R/R-0=-0.91), while the (0 0 118) reflection increases by more than an order of magnitude (Delta R/R-0=24.1). The change of the x-ray structure factor depends nonlinearly on the phonon amplitude, allowing manipulation of the x-ray response on a timescale considerably shorter than the phonon period. Numerical simulations for a superlattice with slightly changed geometry and realistic parameters predict a switching-contrast ratio Delta R/R-0 of 700 with high reflectivity.
A recently developed efficient recursive approach for analytically calculating the short-time evolution of the one-particle propagator to extremely high orders is applied here for numerically studying the thermodynamical and dynamical properties of a rotating ideal Bose gas of Rb-87 atoms in an anharmonic trap. At first, the one-particle energy spectrum of the system is obtained by diagonalizing the discretized short-time propagator. Using this, many-boson properties such as the condensation temperature, the ground-state occupancy, density profiles, and time-of-flight absorption pictures are calculated for varying rotation frequencies. The obtained results improve previous semiclassical calculations, in particular for smaller particle numbers. Furthermore, we find that typical time scales for a free expansion are increased by an order of magnitude for the delicate regime of both critical and overcritical rotation.
Mountain gazelles (Gazella gazella) rank among the most critically endangered mammals on the Arabian Peninsula. Past conservation efforts have been plagued by confusion about the phylogenetic relationship among various 'phenotypically discernable' populations, and even the question of species boundaries was far from being certain. This lack of knowledge has had a direct impact on conservation measures, especially ex situ breeding programmes, hampering the assignment of captive stocks to potential conservation units. Here, we provide a phylogenetic framework, based on the analysis of mtDNA sequences (360 bp cytochrome b and 213 bp Control Region) of 126 individuals collected from the wild throughout the Arabian Peninsula and from captive stocks. Our analyses revealed two reciprocally monophyletic genetic lineages within the presumed species Gazella gazella: one 'northern clade' on the Golan Heights (Israel/Syrian border) and one genetically diverse larger clade from the rest of the Arabian Peninsula including the Arava Valley (Negev, Israel). Applying the Strict Phylogenetic Species Concept (sensu Mishler & Theriot, 2000) allows assigning species status to these two major clades.
The interplay between turnover or degradation and ribosome loading of messenger RNA (mRNA) is studied theoretically using a stochastic model that is motivated by recent experimental results. Random mRNA degradation affects the statistics of polysomes, i.e., the statistics of the number of ribosomes per mRNA as extracted from cells. Since ribosome loading of newly created mRNA chains requires some time to reach steady state, a fraction of the extracted mRNA/ ribosome complexes does not represent steady state conditions. As a consequence, the mean ribosome density obtained from the extracted complexes is found to be inversely proportional to the mRNA length. On the other hand, the ribosome density profile shows an exponential decrease along the mRNA for prokaryotes and becomes uniform in eukaryotic cells. Copyright (C) EPLA, 2010
The iron-containing ionic liquid (IL) 1-butyl-3-methylimidazolium tetrachloroferrate(III) [Bmim][FeCl4] has been used as a building block in the synthesis of transparent, ion-conducting, and paramagnetic ionogels. UV/Vis spectroscopy shows that the coordination around the Fe(III) ion does slightly change upon incorporation of the IL into PMMA. The thermal stability of the PMMA increases significantly with IL incorporation. In particular, the onset weight loss observed at ca. 265 degrees C for pure PMMA is completely suppressed. The ionic conductivity shows a strong temperature dependence and increases with increasing IL weight fractions. The magnetic properties are similar to those reported for the pure IL and are not affected by the incorporation into the PMMA matrix. The resulting ionogel is thus an interesting prototype for soft, flexible, and transparent materials combining the mechanical properties of the matrix with the functionality of the metal-containing IL, such as magnetism.
Seismic wide-angle data were collected along a 40-km-long profile centered at the geothermal research well GrSk 3/90 in the Northeast German Basin. Tomographic inversion of travel time data provided a velocity and a vertical velocity gradient model, indicative of Cenozoic to Pre-Permian sediments. Wide-angle reflections are modeled and interpreted as top Zechstein and top Pre-Permian. Changes in velocity gradients are interpreted as the transition from mechanical to chemical compaction at 2-3 km depth, and localized salt structures are imaged, suggesting a previously unknown salt pillow in the southern part of the seismic profile. The Zechstein salt shows decreased velocities in the adjacent salt pillows compared to the salt lows, which is confirmed by sonic log data. This decrease in velocity could be explained by the mobilization of less dense salt, which moved and formed the salt pillows, whereas the denser salt remained in place at the salt lows. We interpret a narrow subvertical low-velocity zone under the salt pillow at GrSk 3/ 90 as a fault in the deep Permian to Pre-Permian. This WNW-ESE trending fault influenced the location of the salt tectonics and led to the formation of a fault-bounded graben in the Rotliegend sandstones with optimal mechanical conditions for geothermal production. Thermal modeling showed that salt pillows are related to chimney effects, a decrease in temperature, and increasing velocity. The assumed variations in salt lithology, density, and strain must thus be even higher to compensate for the temperature effect.
We present a systematic study of the influence of energy and phase relaxation on dynamic polarizability simulations in the linear response regime. The nonperturbative approach is based on explicit electron dynamics using short laser pulses of low intensities. To include environmental effects on the property calculation, we use the time- dependent configuration-interaction method in its reduced density matrix formulation. Both energy dissipation and nonlocal pure dephasing are included. The explicit treatment of time-resolved electron dynamics gives access to the phase shift between the electric field and the induced dipole moment, which can be used to define a useful uncertainty measure for the dynamic polarizability. The nonperturbative treatment is compared to perturbation theory expressions, as applied to a simple model system, the rigid H-2 molecule. It is shown that both approaches are equivalent for low field intensities, but the time-dependent treatment provides complementary information on the phase of the induced dipole moment, which allows for the definition of an uncertainty associated with the computation of the dynamic polarizability in the linear response regime.
Three dimensional modelling of fractured and faulted reservoirs : framework and implementation
(2010)
Modelling of coupled physical processes in fractured and faulted media is a major challenge for the geoscience community. Due to the complexity related to the geometry of real fracture networks and fault systems, modelling studies have been mainly restricted either to two dimensional cases or to simplified orthogonal fracture systems consisting of vertical and horizontal fractures. An approach to generate three dimensional meshes for realistic fault geometries is presented. The method enables representation of faults in an arbitrary incline as two dimensional planes within a three dimensional, stratified porous matrix of a generic geometry. Based on a structural geological model, the method creates three dimensional unstructured tetrahedral meshes. These meshes can be used for finite element and finite volume numerical simulations. A simulation of a coupled fluid flow and heat transport problem for a two layered porous medium cut by two crossing faults is presented to test the reliability of the method.
We have studied I lie thermal behavior of amphiphilic, symmetric triblock copolymers having short, deuterated polystyrene (PS) end blocks and a large poly(N-isopropylacrylarnicle) (PNIPAM) middle block exhibiting a lower critical solution temperature (LCST) in aqueous solution. A wide range of concentrations (0.1-300 mg/mL) is investigated using it number of analytical methods such as fluorescence correlation spectroscopy (FCS), turbidimetry, dynamic light scattering (DLS), small-angle neutron scattering (SANS), and neutron spin-echo spectroscopy (NSE). The critical micelle concentration is determined using FCS to be 1 mu M or less. The collapse of the micelles at the LCST is investigated using turbidimetry and DLS and shows a weak dependence on the degree of polymerization of the PNIPAM block. SANS with contrast matching allows its to reveal the core-shell Structure of the micelles as well as their correlation as a function of temperature. The segmental dynamics of the PNIPAM shell are studied as a function of temperature and arc found to be faster in the collapsed state than in the swollen state. The mode detected has a linear dispersion in q(2) and is found to be faster in the collapsed state as compared to the swollen state. We attribute this result to the averaging over mobile and immobilized segments.
Several series of symmetrical triblock copolymers were synthesized by the reversible addition fragmentation chain transfer method. They consist of a long block of poly(N-isopropylacrylamide) as hydrophilic, thermoresponsive middle block, which is end-capped by two small strongly hydrophobic blocks made from five different vinyl polymers. The association of the amphiphilic polymers was studied in dilute and concentrated aqueous solution. The polymer micelles found at low concentrations form hydrogels at high concentrations, typically above 30-35 wt.%. Hydrogel formation and the thermosensitive rheological behavior were studied exemplarily for copolymers with hydrophobic blocks of polystyrene, poly(2-ethylhexyl acrylate), and poly(n-octadecyl acrylate). All systems exhibited a cloud point around 30 A degrees C. Heating beyond the cloud point initially favors hydrogel formation but continued heating results in macroscopic phase separation. The rheological behavior suggests that the copolymers associate into flower-like micelles, with only a small share of polymers that bridge the micelles and act as physical cross-linkers, even at high concentrations.
Die Möglichkeiten sich zu informieren, am Leben der vielen Anderen teilzunehmen ist durch das Internet mit seinen Tweets, Google-Angeboten und sozialen Netzwerken wie Facebook ins Unermessliche gewachsen. Zugleich fühlen sich viele Nutzer überfordert und meinen, im Meer der Informationen zu ertrinken. So bekennt Frank Schirrmacher in seinem Buch Payback, dass er den geistigen Anforderungen unserer Zeit nicht mehr gewachsen ist. Sein Kopf komme nicht mehr mit. Er sei unkonzentriert, vergesslich und ständig abgelenkt. Das, was vielen zum Problem geworden ist, sehen viele Studierende eher pragmatisch. Der Wissenserwerb in Zeiten von Internet und E-Learning läuft an Hochschulen häufig nach der Helene-Hegemann-Methode ab: Zunächst machen sich die Studierenden, z.B. im Rahmen einer Studien- oder Hausarbeit, bei Wikipedia „schlau“, ein Einstieg ist geschafft. Anschließend wird dieses Wissen mit Google angereichert. Damit ist Überblickswissen vorhanden. Mit geschickter copy-and-paste-Komposition lässt sich daraus schon ein „Werk“ erstellen. Der ein oder andere Studierende gibt sich mit diesem Wissenserwerb zufrieden und bricht seinen Lernprozess hier bereits ab. Nun ist zwar am Ende jeder Studierende für seinen Wissenserwerb selbst verantwortlich. Die erkennbar unbefriedigende Situation sollte die Hochschulen aber herausfordern, das Internet in Vorlesungen und Seminaren auszuprobieren und sinnvolle Anwendungen zu entwickeln. Beispiele gibt es durchaus. Unter der Metapher E-Learning hat sich ein umfangreicher Forschungsschwerpunkt an den Universitäten entwickelt. Einige Beispiele von vielen: So hat der Osnabrücker Informatik-Professor Oliver Vornberger seine Vorlesungen als Video ins Netz gestellt. Per RSS ist es möglich, Sequenzen aufs iPod zu laden. Die übliche Dozentenangst, dann würden sie ja vor leeren Bänken sitzen, scheint unbegründet. Sie werden von den Studierenden vor allem zur Prüfungsvorbereitung genutzt. Wie ist das Internet, das für die junge Generation zu einem alles andere verdrängenden Universalmedium geworden ist, didaktisch in die Hochschullehre einzubinden? Wie also ist konkret mit diesen Herausforderungen umzugehen? Dies soll uns im Folgenden beschäftigen.
Context. Helicity is a fundamental property of magnetic fields, conserved in ideal MHD. In flux rope geometry, it consists of twist and writhe helicity. Despite the common occurrence of helical structures in the solar atmosphere, little is known about how their shape relates to the writhe, which fraction of helicity is contained in writhe, and how much helicity is exchanged between twist and writhe when they erupt. Aims. Here we perform a quantitative investigation of these questions relevant for coronal flux ropes. Methods. The decomposition of the writhe of a curve into local and nonlocal components greatly facilitates its computation. We use it to study the relation between writhe and projected S shape of helical curves and to measure writhe and twist in numerical simulations of flux rope instabilities. The results are discussed with regard to filament eruptions and coronal mass ejections (CMEs). Results. (1) We demonstrate that the relation between writhe and projected S shape is not unique in principle, but that the ambiguity does not affect low- lying structures, thus supporting the established empirical rule which associates stable forward (reverse) S shaped structures low in the corona with positive (negative) helicity. (2) Kink-unstable erupting flux ropes are found to transform a far smaller fraction of their twist helicity into writhe helicity than often assumed. (3) Confined flux rope eruptions tend to show stronger writhe at low heights than ejective eruptions (CMEs). This argues against suggestions that the writhing facilitates the rise of the rope through the overlying field. (4) Erupting filaments which are S shaped already before the eruption and keep the sign of their axis writhe (which is expected if field of one chirality dominates the source volume of the eruption), must reverse their S shape in the course of the rise. Implications for the occurrence of the helical kink instability in such events are discussed. (5) The writhe of rising loops can easily be estimated from the angle of rotation about the direction of ascent, once the apex height exceeds the footpoint separation significantly. Conclusions. Writhe can straightforwardly be computed for numerical data and can often be estimated from observations. It is useful in interpreting S shaped coronal structures and in constraining models of eruptions.
The Visigoths as the other
(2010)
An analysis of Roman -Visigothic relations in different terms than the usual presupposition of constant military and confessional/Christia n antagonism. Structuralist methodology demonstrates how Roman needs at precise historical moments determ in e how Visigoths were perceived and, therefore, portrayed in our source.
Ecologists carry a well-stocked toolbox with a great variety of sampling methods, statistical analyses and modelling tools, and new methods are constantly appearing. Evaluation and optimisation of these methods is crucial to guide methodological choices. Simulating error-free data or taking high-quality data to qualify methods is common practice. Here, we emphasise the methodology of the 'virtual ecologist' (VE) approach where simulated data and observer models are used to mimic real species and how they are 'virtually' observed. This virtual data is then subjected to statistical analyses and modelling, and the results are evaluated against the 'true' simulated data. The VE approach is an intuitive and powerful evaluation framework that allows a quality assessment of sampling protocols, analyses and modelling tools. It works under controlled conditions as well as under consideration of confounding factors such as animal movement and biased observer behaviour. In this review, we promote the approach as a rigorous research tool, and demonstrate its capabilities and practical relevance. We explore past uses of VE in different ecological research fields, where it mainly has been used to test and improve sampling regimes as well as for testing and comparing models, for example species distribution models. We discuss its benefits as well as potential limitations, and provide some practical considerations for designing VE studies. Finally, research fields are identified for which the approach could be useful in the future. We conclude that VE could foster the integration of theoretical and empirical work and stimulate work that goes far beyond sampling methods, leading to new questions, theories, and better mechanistic understanding of ecological systems.
Ample literature describes the history of the association between the advances in the health and wealth of people, and mortality rates, life expectancy and adult height. Twentynine German studies with n > 200 subjects published since 1848 on menarcheal age, were reanalyzed, and 101 studies from various other European and non-European countries. On average, mean age at menarche declined since the mid-19(th) century. Historic urban samples tended to decline earlier than rural groups, upper class women earlier than working class women. In Germany, minimum values for the age at menarche were seen already between the two World Wars (Leipzig 12.6 years in 1934, Halle 13.3 years in 1939). Values for mean age and SD for age at menarche were strongly associated. With improving historic circumstances, the two parameters declined in parallel. The standard deviation for menarcheal age dropped from over 2.5 years in mid-19th century France to little more or even less than 1 year in most modern countries. In the German studies the correlation between menarcheal age and SD was almost complete with r = 0.96 (y = 0.35x - 3.53). Similar associations between mean age at menarche and SD for age were found in other European countries. The obvious and immediate effects of historic events on menarcheal age, and particularly on the age distribution, indicate that menarche is a sensitive indicator of public health and wealth, and may be an appropriate estimator for the socio-economic background of historic populations.
Metal ion induced self-assembly of the rigid ligand 1,4-bis(2,2':6',2 ''-terpyridine- 4'-yl) benzene (1) with Fe(II), Co(II), Ni(II) and Zn(II) acetate in aqueous solution results in extended, rigid- rod like metallosupramolecular coordination polyelectrolytes (MEPE-1). Under the current experimental conditions the molar masses range from 1000 g mol(-1) up to 500 000 g mol(-1). The molar mass depends on concentration, stoichiometry, metal-ion and time. In addition, we present viscosity measurements, small angle neutron scattering and AFM data. We introduce a protocol to precisely control the stoichiometry during self-assembly using conductometry. The protocol can be used with different terpyridine ligands and the above-mentioned metal ions and is of paramount importance to obtain meaningful and reproducible results. As a control experiment we studied the mononuclear 4'- (phenyl)2,2':6',2 ''-terpyridine (3) complex with Ni(II) and Zn(II) and the flexible ligand 1,3- bis[4'-oxa(2,2': 6',2 ''-terpyridinyl)] propane (2) with Ni(II) acetate (Ni-MEPE-2). This ligand does not form extended macroassemblies but likely ring-like structures with 3 to 4 repeat units. Through spin- coating of Ni-MEPE-1 on a solid surface we can image the MEPEs in real space by AFM. SANS measurements of Fe-MEPE-1 verify the extended rigid-rod type structure of the MEPEs in aqueous solution.
Eye movements during the reading of multi-line pages of texts were analyzed to determine the trajectory of reading saccades. The results of two experiments showed that the trajectory of the majority of forward-directed saccades was negatively biased, i.e., the trajectory fell below the start and end location of the saccadic movement. This is attributed to a global top-to-bottom orienting of attention. The curvature size and the proportion of negative trajectories were diminished when linguistic processing demands were high and when the beginning lines of a page were read. Longer pre-saccadic fixations also yielded smaller saccadic curvatures, and they resulted in fewer negatively curved forward-directed saccades in Experiment 1 although not in Experiment 2. These findings indicate that the top-to- bottom pull of saccadic trajectories is modulated by processing demands and processing opportunities. The results are in general agreement with a time-locked attraction-inhibition hypothesis, according to which the horizontal movement component of a saccade is initially subject to an automatic top-to-bottom orienting of attention that is subsequently inhibited.
e movements during the reading of multi-line pages of texts were analyzed to determine the trajectory of reading saccades. The results of two experiments showed that the trajectory of the majority of forward-directed saccades was negatively biased, i.e., the trajectory fell below the start and end location of the saccadic movement. This is attributed to a global top-to-bottom orienting of attention. The curvature size and the proportion of negative trajectories were diminished when linguistic processing demands were high and when the beginning lines of a page were read. Longer pre-saccadic fixations also yielded smaller saccadic curvatures, and they resulted in fewer negatively curved forward-directed saccades in Experiment 1 although not in Experiment 2. These findings indicate that the top-to- bottom pull of saccadic trajectories is modulated by processing demands and processing opportunities. The results are in general agreement with a time-locked attraction-inhibition hypothesis, according to which the horizontal movement component of a saccade is initially subject to an automatic top-to-bottom orienting of attention that is subsequently inhibited.
Question Which mechanisms promote the maintenance of the protected pioneer grass Corynephorus canescens in a mosaic landscape? Which are the interactive effects of small-scale disturbances, successional stage and year-to-year variation on early establishment probabilities of C. canescens? Location Brandenburg, NE Germany. Methods We measured emergence and survival rates over 3 yr in a sowing-experiment conducted in three successional stages (C. canescens- dominated site, ruderal forb site and pioneer forest) under two different regimes of mechanical ground disturbance (disturbed versus undisturbed control). Results Overall, disturbance led to higher emergence in a humid year and to lower emergence in a very dry year. Apparently, when soil moisture was sufficient, the main factor limiting C. canescens' establishment was competition, while in the dry year, water became the limiting factor. Survival rates were not affected by disturbance. In humid years, C. canescens emerged in higher numbers in open successional stages while in the dry year, emergence rates were higher in late stages, suggesting an important role of late successional stages for the persistence of C. canescens. Conclusions Our results suggest that small-scale disturbances can promote germination of C. canescens. However, disturbances should be carefully planned. The optimal strategy for promoting C. canescens is to apply disturbances just before seed dispersal and not during dry years. At the landscape scale, a mosaic of different vegetation types is beneficial for the protected pioneer grass as facilitation by late-successional species may be an important mechanism for the persistence of C. canescens, especially in dry years.
The biogenic amine octopamine and its biological precursor tyramine are thought to be the invertebrate functional homologues of the vertebrate adrenergic transmitters. Octopamine functions as a neuromodulator, neurotransmitter and neurohormone in insect nervous systems and prompts the whole organism to "dynamic action". A growing number of studies suggest a prominent role for octopamine in modulating multiple physiological and behavioural processes in invertebrates, as for example the phase transition in Schistocerca gregaria. Both octopamine and tyramine exert their effects by binding to specific receptor proteins that belong to the superfamily of G protein-coupled receptors. Since these receptors do not appear to be present in vertebrates, they may present very suitable and specific insecticide and acaricide targets. (C) 2010 Elsevier Ltd. All rights reserved.
The red clover isoflavone irilone is largely resistant to degradation by the human gut microbiota
(2010)
Intestinal bacteria may influence bioavailability and physiological activity of dietary isoflavones. We therefore investigated the ability of human intestinal microbiota to convert irilone and genistein in vitro. In contrast to genistein, irilone was largely resistant to transformation by fecal slurries of ten human subjects. The fecal microbiota converted genistein to dihydrogenistein, 6'-hydroxy-O-desmethylangolensin, and 2-(4-hydroxyphenyl)- propionic acid. However, considerable interindividual differences in the rate of genistein degradation and the pattern of metabolites formed from genistein were observed. Only one metabolite, namely dihydroirilone, was formed from irilone in minor amounts. In further experiments, Eubacterium ramulus, a prevalent flavonoid-degrading species of the human gut, was tested for transformation of irilone. In contrast to genistein, irilone was not converted by E. ramulus. Irilone only differs from genistein by a methylenedioxy group attached to the A-ring of the isoflavone skeleton. This substitution obviously restricts the degradability of irilone by human intestinal bacteria.
3,4-Dihydro-2-H-pyran and oxalyl chloride react, depending on the conditions, to keto esters, a pyran-3- carboxylic acid or derivatives thereof, or to an hitherto unknown bicyclic acetal containing a vinyl chloride moiety. The structure of the latter product has been unambiguously elucidated by single-crystal X-ray structure analysis. A mechanism for its formation is proposed.
The power of apology
(2010)
Global climate and the atmospheric partial pressure of carbon dioxide (p(CO2atm)) are correlated over recent glacial cycles, with lower p(CO2atm) during ice ages, but the causes of the p(CO2atm) changes are unknown. The modern Southern Ocean releases deeply sequestered CO2 to the atmosphere. Growing evidence suggests that the Southern Ocean CO2 'leak' was stemmed during ice ages, increasing ocean CO2 storage. Such a change would also have made the global ocean more alkaline, driving additional ocean CO2 uptake. This explanation for lower ice-age p(CO2atm), if correct, has much to teach us about the controls on current ocean processes.
The tettigoniid genus Phlesirtes Bolivar and its allies are reviewed. Morphological, ecological and molecular data prompt the erection of the new genus Chortoscirtes gen.n. with type species Xiphidion meruense Sjostedt. The genera Phlesirtes, Chortoscirtes, Karniella and Naskreckiella are characterized by morphological characters supported by molecular, acoustic, ecological and chromosomal data. Four species, Chortoscirtes pseudomeruensis sp.n., C. masaicus sp.n., C. puguensis sp.n. and C. serengeti sp.n., are described from localities in northern and coastal Tanzania and one Karniella, K. crassicerca sp.n., is described from Uganda. The following comb n. are proposed: Phlesirtes kibonotensis (Sjostedt) and Phlesirtes kilimandjaricus (Sjostedt). Subtribal status is proposed for the four investigated African genera. A key to the Chortoscirtes species is provided.
Reflecting on how and with what kind of consequences something artificial, something manufactured becomes naturalized in video games will be the central issue of this text. It deals with the question of how the video game hides its artificiality in terms of technique. In a certain sense this retrieves one of the fundamental questions of modernity and industrialization: How does the manufacturing of our environment become a naturalized, self-evident and indubitable process?
Amphibole and mica Ar-40/Ar-39 ages as well as zircon, rutile and titanite U-Pb geochronology of eclogites and associated host rocks from the Higher Himalayan Crystalline Nappes (Indian Plate) in the Upper Kaghan Valley, Pakistan allow distinction of a multistage exhumation history. An Eocene age for peak-pressure metamorphism has been obtained by phengite Ar-40/Ar-39 (47.3 +/- 0.3 Ma) and zircon U-Pb (47.3 +/- 0.4 and 47.4 +/- 0.3 Ma) ages from cover and basement gneisses. A very short-lived metamorphic peak and rapid cooling is documented by an amphibole Ar-40/Ar-39 age of 46.6 +/- 0.5 Ma and a rutile U-Pb age of 44.1 +/- 1.3 Ma from eclogites. Phengite and biotite ages from cover and basement sequences metamorphosed during the Himalayan orogeny are 34.5 +/- 0.2 to 28.1 +/- 0.2 Ma whereas youngest biotites, yielding 23.6 +/- 0.1 and 21.7 +/- 0.2 Ma, probably reflect argon partial resetting. The amphibole age, together with those derived from phengite and zircon demonstrate a rate of initial exhumation of 86-143 mm/a i.e. an extremely rapid transport of the Indian Plate continental crust from ultra-high pressure (UHP) conditions back to crustal levels (47-46 Ma for transport from 140 to 40 km depth). Subsequent exhumation (46-41 Ma, 40-35 km) slowed to about 1 mm/a at the base of the continental crust but increased again later towards slightly higher exhumation rates of ca. 2 mm/a (41-34 Ma, 35- 20 km). This indicates a change from buoyancy-driven exhumation at mantle depths to compression forces related to continent-continent collision and accompanied crustal folding, thrusting and stacking that finally exposed the former deeply-buried rocks.
Communication, simulation, interactive narrative and ubiquitous computing are widely accepted as perspectives in humancomputer interaction. This paper proposes play as another possible perspective. Everyday uses of the computer increasingly show signs of similarity to play. This is not discussed with regard to the so-called media society, the playful society, the growing cultural acceptance of the computer, the spread of computer games or a new version of Windows, but in view of the playful character of interaction with the computer that has always been part of it. The exploratory learning process involved with new software and the creative tasks that are often undertaken when using the computer may support this argument. Together with its high level of interactivity, these observations point to a sense of security, autonomy and freedom of the user that produce play and are, in turn, produced by play. This notion of play refers not to the playing of computer games, but to an implicit, abstract (or symbolic) process based on a certain attitude, the play spirit. This attitude is discussed regarding everyday computer use and related to the other mentioned perspectives.
We show that the residue density of the logarithm of a generalized Laplacian on a closed manifold definesan invariant polynomial-valued differential form. We express it in terms of a finite sum of residues ofclassical pseudodifferential symbols. In the case of the square of a Dirac operator, these formulas providea pedestrian proof of the Atiyah–Singer formula for a pure Dirac operator in four dimensions and for atwisted Dirac operator on a flat space of any dimension. These correspond to special cases of a moregeneral formula by Scott and Zagier. In our approach, which is of perturbative nature, we use either aCampbell–Hausdorff formula derived by Okikiolu or a noncommutative Taylor-type formula.
The biochemical function of the Laforin-like dual-specific phosphatase AtSEX4 (EC 3.1.3.48) has been studied. Crystalline maltodextrins representing the A- or the B-type allomorph were prephosphorylated using recombinant glucan, water dikinase (StGWD) or the successive action of both plastidial dikinases (StGWD and AtPWD). AtSEX4 hydrolyzed carbon 6-phosphate esters from both the prephosphorylated A- and B-type allomorphs and the kinetic constants are similar. The phosphatase also acted on prelabeled carbon-3 esters from both crystalline maltodextrins. Similarly, native starch granules prelabeled in either the carbon-6 or carbon-3 position were also dephosphorylated by AtSEX4. The phosphatase did also hydrolyze phosphate esters of both prephosphorylated maltodextrins when the (phospho)glucans had been solubilized by heat treatment. Submillimolar concentrations of nonphosphorylated maltodextrins inhibited AtSEX4 provided they possessed a minimum of length and had been solubilized. As opposed to the soluble phosphomaltodextrins, the AtSEX4- mediated dephosphorylation of the insoluble substrates was incomplete and at least 50% of the phosphate esters were retained in the pelletable (phospho) glucans. The partial dephosphorylation of the insoluble glucans also strongly reduced the release of nonphosphorylated chains into solution. Presumably, this effect reflects fast structural changes that following dephosphorylation occur near the surface of the maltodextrin particles. A model is proposed defining distinct stages within the phosphorylation/dephosphorylation-dependent transition of alpha-glucans from the insoluble to the soluble state.
Jacobaea vulgaris (Asteraceae) is a species of Eurasian origin that has become a serious non-indigenous weed in Australia, New Zealand, and North America. We used neutral molecular markers to (1) test for genetic bottlenecks in invasive populations and (2) to investigate the invasion pathways. It is for the first time that molecular markers were used to unravel the process of introduction in this species. The genetic variation of 15 native populations from Europe and 16 invasive populations from Australia, New Zealand and North America were compared using the amplified fragment length polymorphisms (AFLP's). An analysis of molecular variance showed that a significant part (10%) of the total genetic variations between all individuals could be explained by native or invasive origin. Significant among-population differentiation was detected only in the native range, whereas populations from the invasive areas did not significantly differ from each other; nor did the Australian, New Zealand and North American regions differ within the invasive range. The result that native populations differed significantly from each other and that the amount of genetic variation, measured as the number of polymorphic bands, did not differ between the native and invasive area, strongly suggests that introductions from multiple source populations have occurred. The lack of differentiation between invasive regions suggests that either introductions may have occurred from the same native sources in all invasive regions or subsequent introductions took place from one into another invasive region and the same mix of genotypes was subsequently introduced into all invasive regions. An assignment test showed that European populations from Ireland, the Netherlands and the United Kingdom most resembled the invasive populations.
Risk attitudes influence the complete life cycle of entrepreneurs. Whereas recent research underpins the theoretical proposition of a positive correlation between risk attitudes and the decision to become self-employed, the effects on survival are not as straightforward. Psychological research posits an inverse U-shaped relationship between risk attitudes and entrepreneurial survival. On the basis of experimentally validated data of the German Socio-Economic Panel (SOEP), we examine the extent to which risk attitudes influence survival rates in self-employment in Germany. The empirical results confirm that persons whose risk attitudes are in the medium range survive significantly longer as entrepreneurs than do persons with particularly low or high risk attitudes.