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Background: Recent studies using transcript and metabolite profiles of wild-type and gene deletion mutants revealed that photorespiratory pathways are essential for the growth of Synechocystis sp. PCC 6803 under atmospheric conditions. Pool size changes of primary metabolites, such as glycine and glycolate, indicated a link to photorespiration.
Methodology/Principal Findings: The (13)C labelling kinetics of primary metabolites were analysed in photoautotrophically grown cultures of Synechocystis sp. PCC 6803 by gas chromatography-mass spectrometry (GC-MS) to demonstrate the link with photorespiration. Cells pre-acclimated to high CO(2) (5%, HC) or limited CO(2) (0.035%, LC) conditions were pulse-labelled under very high (2% w/w) (13)C-NaHCO(3) (VHC) conditions followed by treatment with ambient (12)C at HC and LC conditions, respectively. The (13)C enrichment, relative changes in pool size, and (13)C flux of selected metabolites were evaluated. We demonstrate two major paths of CO(2) assimilation via Rubisco in Synechocystis, i.e., from 3PGA via PEP to aspartate, malate and citrate or, to a lesser extent, from 3PGA via glucose-6-phosphate to sucrose. The results reveal evidence of carbon channelling from 3PGA to the PEP pool. Furthermore, (13)C labelling of glycolate was observed under conditions thought to suppress photorespiration. Using the glycolate-accumulating Delta glcD1 mutant, we demonstrate enhanced (13)C partitioning into the glycolate pool under conditions favouring photorespiration and enhanced (13)C partitioning into the glycine pool of the glycine-accumulating Delta gcvT mutant. Under LC conditions, the photorespiratory mutants Delta glcD1 and Delta gcvT showed enhanced activity of the additional carbon-fixing PEP carboxylase pathway.
Conclusions/Significance: With our approach of non-steady-state (13)C labelling and analysis of metabolite pool sizes with respective (13)C enrichments, we identify the use and modulation of major pathways of carbon assimilation in Synechocystis in the presence of high and low inorganic carbon supplies.
We establish a link between unitary relaxation dynamics after a quench in closed many-body systems and the entanglement in the energy eigenbasis. We find that even if reduced states equilibrate, they can have memory on the initial conditions even in certain models that are far from integrable. We show that in such situations the equilibrium states are still described by a maximum entropy or generalized Gibbs ensemble, regardless of whether a model is integrable or not, thereby contributing to a recent debate. In addition, we discuss individual aspects of the thermalization process, comment on the role of Anderson localization, and collect and compare different notions of integrability.
In this paper, we perform many-electron dynamics using the time-dependent configuration-interaction method in its reduced density matrix formulation (rho-TDCI). Dissipation is treated implicitly using the Lindblad formalism. To include the effect of ionization on the state-resolved dynamics, we extend a recently introduced heuristic model for ionizing states to the rho-TDCI method, which leads to a reduced density matrix evolution that is not norm-preserving. We apply the new method to the laser-driven excitation of H(2) in a strongly dissipative environment, for which the state-resolve lifetimes are tuned to a few femtoseconds, typical for dynamics of adsorbate at metallic surfaces. Further testing is made on the laser-induced intramolecular charge transfer in a quinone derivative as a model for a molecular switch. A modified scheme to treat ionizing states is proposed to reduce the computational burden associated with the density matrix propagation, and it is thoroughly tested and compared to the results obtained with the former model. The new approach scales favorably (similar to N(2)) with the number of configurations N used to represent the reduced density matrix in the rho-TDCI method, as compared to a N(3) scaling for the model in its original form.
We study changes in effective stress (normal stress minus pore pressure) that occurred in the French Alps during the 2003-2004 Ubaye earthquake swarm. Two complementary data sets are used. First, a set of 974 relocated events allows us to finely characterize the shape of the seismogenic area and the spatial migration of seismicity during the crisis. Relocations are performed by a double-difference algorithm. We compute differences in travel times at stations both from absolute picking times and from cross-correlation delays of multiplets. The resulting catalog reveals a swarm alignment along a single planar structure striking N130 degrees E and dipping 80 degrees W. This relocated activity displays migration properties consistent with a triggering by a diffusive fluid overpressure front. This observation argues in favor of a deep-seated fluid circulation responsible for a significant part of the seismic activity in Ubaye. Second, we analyze time series of earthquake detections at a single seismological station located just above the swarm. This time series forms a dense chronicle of +16,000 events. We use it to estimate the history of effective stress changes during this sequence. For this purpose we model the rate of events by a stochastic epidemic-type aftershock sequence model with a nonstationary background seismic rate lambda(0)(t). This background rate is estimated in discrete time windows. Window lengths are determined optimally according to a new change-point method on the basis of the interevent times distribution. We propose that background events are triggered directly by a transient fluid circulation at depth. Then, using rate-and-state constitutive friction laws, we estimate changes in effective stress for the observed rate of background events. We assume that changes in effective stress occurred under constant shear stressing rate conditions. We finally obtain a maximum change in effective stress close to -8 MPa, which corresponds to a maximum fluid overpressure of about 8 MPa under constant normal stress conditions. This estimate is in good agreement with values obtained from numerical modeling of fluid flow at depth, or with direct measurements reported from fluid injection experiments.
Cellulose delta O-18 is an index of leaf-to-air vapor pressure difference (VPD) in tropical plants
(2011)
Cellulose in plants contains oxygen that derives in most cases from precipitation. Because the stable oxygen isotope composition, delta O-18, of precipitation is associated with environmental conditions, cellulose delta O-18 should be as well. However, plant physiological models using delta O-18 suggest that cellulose delta O-18 is influenced by a complex mix of both climatic and physiological drivers. This influence complicates the interpretation of cellulose delta O-18 values in a paleo-context. Here, we combined empirical data analyses with mechanistic model simulations to i) quantify the impacts that the primary climatic drivers humidity (e(a)) and air temperature (T-air) have on cellulose delta O-18 values in different tropical ecosystems and ii) determine which environmental signal is dominating cellulose delta O-18 values. Our results revealed that e(a) and T-air equally influence cellulose delta O-18 values and that distinguishing which of these factors dominates the delta O-18 values of cellulose cannot be accomplished in the absence of additional environmental information. However, the individual impacts of e(a) and T-air on the delta O-18 values of cellulose can be integrated into a single index of plant-experienced atmospheric vapor demand: the leaf-to-air vapor pressure difference (VPD). We found a robust relationship between VPD and cellulose delta O-18 values in both empirical and modeled data in all ecosystems that we investigated. Our analysis revealed therefore that delta O-18 values in plant cellulose can be used as a proxy for VPD in tropical ecosystems. As VPD is an essential variable that determines the biogeochemical dynamics of ecosystems, our study has applications in ecological-, climate-, or forensic-sciences.
Working memory maintenance of grasp-target information in the human posterior parietal cortex
(2011)
Event-related functional magnetic resonance imaging was applied to identify cortical areas involved in maintaining target information in working memory used for an upcoming grasping action. Participants had to grasp with their thumb and index finger of the dominant right hand three-dimensional objects of different size and orientation. Reaching-to-grasp movements were performed without visual feedback either immediately after object presentation or after a variable delay of 2-12 s. The right inferior parietal cortex demonstrated sustained neural activity throughout the delay, which overlapped with activity observed during encoding of the grasp target. Immediate and delayed grasping activated similar motor-related brain areas and showed no differential activity. The results suggest that the right inferior parietal cortex plays an important functional role in working memory maintenance of grasp-related information. Moreover, our findings confirm the assumption that brain areas engaged in maintaining information are also involved in encoding the same information, and thus extend previous findings on working memory function of the posterior parietal cortex in saccadic behavior to reach-to-grasp movements.
Background and objective Whether treatment with vitamin D receptor activators contributes to cardiovascular disease in patients with chronic kidney disease is a matter of debate. We studied mechanisms involved in vitamin D-related vascular calcifications in vivo and in vitro.
Methods Aortic calcifications were induced in subtotally nephrectomized (SNX) rats by treatment with a high dose (0.25 mu g/kg per day) of 1,25-dihydroxyvitamin D-3 (calcitriol) given for 6 weeks. Likewise, primary rat vascular smooth muscle cells (VSMCs) were incubated with calcitriol at concentrations ranging from 10(-11) to 10(-7) mol/l. Immunohistochemistry revealed that the aortic expression of osteopontin, osteocalcin and bone sialoprotein was significantly increased in calcitriol-treated SNX rats compared to untreated SNX controls. In addition, aortic expression of the transient receptor potential vanilloid calcium channel 6 (TRPV6) and calbindin D9k was significantly up-regulated by treatment with calcitriol. Furthermore, calcitriol significantly increased expression of the osteogenic transcription factor osterix. In-vitro studies showed similar results, confirming that these effects could be attributed to treatment with calcitriol.
Conclusions High-dose calcitriol treatment induces an osteoblastic phenotype in VSMC both in SNX rats and in vitro, associated with up-regulation of proteins regulating mineralization and calcium transport, and of the osteogenic transcription factor osterix.
Background:
Recent studies have identified a Child Behavior Checklist profile that characterizes children with severe affective and behavioral dysregulation (CBCL-dysregulation profile, CBCL-DP). In two recent longitudinal studies the CBCL-DP in childhood was associated with heightened rates of comorbid psychiatric disorders, among them bipolar disorder, an increased risk for suicidality, and marked psychosocial impairment at young-adult follow-up. This is the first study outside the US that examines the longitudinal course of the CBCL-DP.
Methods:
We studied the diagnostic and functional trajectories and the predictive utility of the CBCL-DP in the Mannheim Study of Children at Risk, an epidemiological cohort study on the outcome of early risk factors from birth into adulthood. A total of 325 young adults (151 males, 174 females) participated in the 19-year assessment.
Results:
Young adults with a higher CBCL-DP score in childhood were at increased risk for substance use disorders, suicidality and poorer overall functioning at age 19, even after adjustment for parental education, family income, impairment and psychiatric disorders at baseline. Childhood dysregulation was not related to bipolar disorder in young adulthood. The CBCL-DP was neither a precursor of a specific pattern of comorbidity nor of comorbidity in general.
Conclusions:
Children with high CBCL-DP values are at risk for later severe, psychiatric symptomatology. The different developmental trajectories suggest that the CBCL-DP is not simply an early manifestation of a single disease process but might rather be an early developmental risk marker of a persisting deficit of self-regulation of affect and behavior.
Biopolymers of the extracellular matrix are attractive starting materials for providing degradable and biocompatible biomaterials. In this study, hyaluronic acid-based hydrogels with tunable mechanical properties were prepared by the use of copper-catalyzed azide-alkyne cycloaddition (known as "click chemistry"). Alkyne-functionalized hyaluronic acid was crosslinked with linkers having two terminal azide functionalities, varying crosslinker density as well as the lengths and rigidity of the linker molecules. By variation of the crosslinker density and crosslinker type, hydrogels with elastic moduli in the range of 0.5-4 kPa were prepared. The washed materials contained a maximum of 6.8 mg copper per kg dry weight and the eluate of the gel crosslinked with diazidostilbene did not show toxic effects on L929 cells. The hyaluronic acid-based hydrogels have potential as biomaterials for cell culture or soft tissue regeneration applications.
Breakdown threshold of dielectric barrier discharges in ferroelectrets where Paschen's law fails
(2011)
The piezoelectric activity of charged cellular foams (so-called ferroelectrets) is compared against simulations based on a multi-layer electromechanical model and Townsend's model of Paschen breakdown, with the distribution of void heights determined from scanning electron micrographs. While the calculated space charge hysteresis curves are in good agreement with experimental data, the onset of piezoelectric activity is observed at significantly higher electric fields than predicted by Paschen's law. One likely explanation is that the commonly accepted Paschen curve for electric breakdown in air poorly describes the critical electric field for dielectric barrier discharges in micrometer-size cavities.
Polymer foams and void-containing polymer-film systems with internally charged voids combine large piezoelectricity with mechanical flexibility and elastic compliance. This new class of soft materials (often called ferro-or piezoelectrets) has attracted considerable attention from science and industry. It has been found that the voids can be internally charged by means of dielectric barrier discharges (DBDs) under high electric fields. The charged voids can be considered as man-made macroscopic dipoles. Depending on the ferroelectret structure and the pressure of the internal gas, the voids may be highly compressible. Consequently, very large dipole-moment changes can be induced by mechanical or electrical stresses, leading to large piezoelectricity. DBD charging of the voids is a critical process for rendering polymer foams piezoelectric. Thus a comprehensive exploration of DBD charging is essential for the understanding and the optimization of piezoelectricity in ferroelectrets. Recent studies show that DBDs in the voids are triggered when the internal electric field reaches a threshold value according to Townsend's model of Paschen breakdown. During the DBDs, charges of opposite polarity are generated and trapped at the top and bottom internal surfaces of the gas-filled voids, respectively. The deposited charges induce an electric field opposite to the externally applied one and thus extinguish the DBDs. Back discharges may eventually be triggered when the external voltage is reduced or turned off. In order to optimize the efficiency of DBD charging, the geometry (in particular the height) of the voids, the type of gas and its pressure inside the voids are essential factors to be considered and to be optimized. In addition, the influence of the plasma treatment on the internal void surfaces during the DBDs should be taken into consideration.
This paper investigates the effect of chemical surface modification of polytetrafluoroethylene (PTFE) and low density polyethylene (LDPE) films on their electret properties. PTFE films were subjected to wet treatment with three different chemicals: orthophosphoric acid, tetrabutyl titanate and tetraethoxysilane. The technique based on the principles of molecular layer deposition (MLD) method was used to modify the surface of LDPE films with phosphorus trichloride vapors. The surfaces of the films were then corona charged, and the electret charge stability was studied by means of isothermal and thermally stimulated surface potential decay. Both PTFE and LDPE films, after the surface treatment, displayed a considerable enhancement in the charge stability compared to the virgin samples. It is important to note that the enhancement of the charge stability was achieved in the positively charged PTFE films, a result important to practical applications. We attribute this effect of charge stabilization to the formation of new energetically deep traps on the modified surface. Decrease in molecular mobility, due to attachment of new chemical structures to the surface macromolecules, may also contribute to the overall growth of the charge stability.
Analysis of the operating characteristics of a dielectric elastomer actuator (DEA) submount for the high-precision positioning of optical components in one dimension is presented. Precise alignment of a single-mode fiber is demonstrated and variation of the sensitivity of the submount motion by changing the bias voltage is confirmed. A comparison of the performance of the DEA submount with a piezoelectric alignment stage is made, which demonstrates that DEAs could present a very attractive, low-cost alternative to currently used manual technologies in overcoming the hurdle of expensive packaging of single-mode optical components.
For the eschatology of socialism. Hendrik de Man's contribution to the concept of "secular Religion"
(2011)
Continent-ocean-transition across a trans-tensional margin segment: off Bear Island, Barents Sea
(2011)
P>A 410 km long Ocean Bottom Seismometer profile spanning from the Bear Island, Barents Sea to oceanic crust formed along the Mohns Ridge has been modelled by use of ray-tracing with regard to observed P-waves. The northeastern part of the model represents typical continental crust, thinned from ca. 30 km thickness beneath the Bear Island to ca. 13 km within the Continent-Ocean-Transition. Between the Hornsund FZ and the Kn circle divide legga Fault, a 3-4 km thick sedimentary basin, dominantly of Permian/Carboniferous age, is modelled beneath the ca. 1.5 km thick layer of volcanics (Vestbakken Volcanic Province). The P-wave velocity in the 3-4 km thick lowermost continental crust is significantly higher than normal (ca. 7.5 km s-1). We interpret this layer as a mixture of mafic intrusions and continental crystalline blocks, dominantly related to the Paleocene-Early Eocene rifting event. The crystalline portion of the crust within the south-western part of the COT consists of a ca. 30 km wide and ca. 6 km thick high-velocity (7.3 km s-1) body. We interpret the body as a ridge of serpentinized peridotites. The magmatic portion of the ocean crust accreted along the Knipovich Ridge from continental break-up at ca. 35 Ma until ca. 20 Ma is 3-5 km thicker than normal. We interpret the increased magmatism as a passive response to the bending of this southernmost part of the Knipovich Ridge. The thickness of the magmatic portion of the crust formed along the Mohns Ridge at ca. 20 Ma decreases to ca. 3 km, which is normal for ultra slow spreading ridges.
We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900-2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits.
Both species displayed a significant 4% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium.
The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.
Folding at the birth of the nascent chain: coordinating translation with co-translational folding
(2011)
In the living cells, the folding of many proteins is largely believed to begin co-translationally, during their biosynthesis at the ribosomes. In the ribosomal tunnel, the nascent peptide may establish local interactions and stabilize alpha-helical structures. Long-range contacts are more likely outside the ribosomes after release of larger segments of the nascent chain. Examples suggest that domains can attain native-like structure on the ribosome with and without population of folding intermediates. The co-translational folding is limited by the speed of the gradual extrusion of the nascent peptide which imposes conformational restraints on its folding landscape. Recent experimental and in silico modeling studies indicate that translation kinetics fine-tunes co-translational folding by providing a time delay for sequential folding of distinct portions of the nascent chain.
We present an alarm-based earthquake forecast model that uses the early aftershock statistics (EAST). This model is based on the hypothesis that the time delay before the onset of the power-law aftershock decay rate decreases as the level of stress and the seismogenic potential increase. Here, we estimate this time delay from < t(g)>, the time constant of the Omori-Utsu law. To isolate space-time regions with a relative high level of stress, the single local variable of our forecast model is the E-a value, the ratio between the long-term and short-term estimations of < t(g)>. When and where the E-a value exceeds a given threshold (i.e., the c value is abnormally small), an alarm is issued, and an earthquake is expected to occur during the next time step. Retrospective tests show that the EAST model has better predictive power than a stationary reference model based on smoothed extrapolation of past seismicity. The official prospective test for California started on 1 July 2009 in the testing center of the Collaboratory for the Study of Earthquake Predictability (CSEP). During the first nine months, 44 M >= 4 earthquakes occurred in the testing area. For this time period, the EAST model has better predictive power than the reference model at a 1% level of significance. Because the EAST model has also a better predictive power than several time-varying clustering models tested in CSEP at a 1% level of significance, we suggest that our successful prospective results are not due only to the space-time clustering of aftershocks.
Spatiotemporal dynamics of the Calvin cycle multistationarity and symmetry breaking instabilities
(2011)
The possibility of controlling the Calvin cycle has paramount implications for increasing the production of biomass. Multistationarity, as a dynamical feature of systems, is the first obvious candidate whose control could find biotechnological applications. Here we set out to resolve the debate on the multistationarity of the Calvin cycle. Unlike the existing simulation-based studies, our approach is based on a sound mathematical framework, chemical reaction network theory and algebraic geometry, which results in provable results for the investigated model of the Calvin cycle in which we embed a hierarchy of realistic kinetic laws. Our theoretical findings demonstrate that there is a possibility for multistationarity resulting from two sources, homogeneous and inhomogeneous instabilities, which partially settle the debate on multistability of the Calvin cycle. In addition, our tractable analytical treatment of the bifurcation parameters can be employed in the design of validation experiments.
Under natural conditions, plants are exposed to rapidly changing light intensities. To acclimate to such fluctuations, plants have evolved adaptive mechanisms that optimally exploit available light energy and simultaneously minimise damage of the photosynthetic apparatus through excess light. An important mechanism is the dissipation of excess excitation energy as heat which can be measured as nonphotochemical quenching of chlorophyll fluorescence (NPQ). In this paper, we present a highly simplified mathematical model that captures essential experimentally observed features of the short term adaptive quenching dynamics. We investigate the stationary and dynamic behaviour of the model and systematically analyse the dependence of characteristic system properties on key parameters such as rate constants and pool sizes. Comparing simulations with experimental data allows to derive conclusions about the validity of the simplifying assumptions and we further propose hypotheses regarding the role of the xanthophyll cycle in NPQ. We envisage that the presented theoretical description of the light reactions in conjunction with short term adaptive processes serves as a basis for the development of more detailed mechanistic models by which the molecular mechanisms of NPQ can be theoretically studied.
In alphabetic writing systems, saccade amplitude (a close correlate of reading speed) is independent of font size, presumably because an increase in the angular size of letters is compensated for by a decrease of visual acuity with eccentricity. We propose that this invariance may (also) be due to the presence of spaces between words, guiding the eyes across a large range of font sizes. Here, we test whether saccade amplitude is also invariant against manipulations of font size during reading Chinese, a character-based writing system without spaces as explicit word boundaries for saccade-target selection. In contrast to word-spaced alphabetic writing systems, saccade amplitude decreased significantly with increased font size, leading to an increase in the number of fixations at the beginning of words and in the number of refixations. These results are consistent with a model which assumes that word beginning (rather than word center) is the default saccade target if the length of the parafoveal word is not available.
We report on the gamma-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) gamma-ray spectrum of Mrk 501 can be well described by a single power-law function with a photon index of 1.78 +/- 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of two), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 +/- 0.14, and the softest one is 2.51 +/- 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3 GeV. In this paper, we also present the first results from the 4.5 month long multifrequency campaign (2009 March 15-August 1) on Mrk 501, which included the Very Long Baseline Array (VLBA), Swift, RXTE, MAGIC, and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The extensive radio to TeV data set from this campaign provides us with the most detailed spectral energy distribution yet collected for this source during its relatively low activity. The average spectral energy distribution of Mrk 501 is well described by the standard one-zone synchrotron self-Compton (SSC) model. In the framework of this model, we find that the dominant emission region is characterized by a size less than or similar to 0.1 pc (comparable within a factor of few to the size of the partially resolved VLBA core at 15-43 GHz), and that the total jet power (similar or equal to 10(44) erg s(-1)) constitutes only a small fraction (similar to 10(-3)) of the Eddington luminosity. The energy distribution of the freshly accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3 GeV-10 TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20 GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk 501 is due to relativistic, proton-mediated shocks. We find that the ultrarelativistic electrons and mildly relativistic protons within the blazar zone, if comparable in number, are in approximate energy equipartition, with their energy dominating the jet magnetic field energy by about two orders of magnitude.
Aims. We study an evolving bipolar active region that exhibits flux cancellation at the internal polarity inversion line, the formation of a soft X-ray sigmoid along the inversion line and a coronal mass ejection. The aim is to investigate the quantity of flux cancellation that is involved in flux rope formation in the time period leading up to the eruption.
Methods. The active region is studied using its extreme ultraviolet and soft X-ray emissions as it evolves from a sheared arcade to flux rope configuration. The evolution of the photospheric magnetic field is described and used to estimate how much flux is reconnected into the flux rope.
Results. About one third of the active region flux cancels at the internal polarity inversion line in the 2.5 days leading up to the eruption. In this period, the coronal structure evolves from a weakly to a highly sheared arcade and then to a sigmoid that crosses the inversion line in the inverse direction. These properties suggest that a flux rope has formed prior to the eruption. The amount of cancellation implies that up to 60% of the active region flux could be in the body of the flux rope. We point out that only part of the cancellation contributes to the flux in the rope if the arcade is only weakly sheared, as in the first part of the evolution. This reduces the estimated flux in the rope to similar to 30% or less of the active region flux. We suggest that the remaining discrepancy between our estimate and the limiting value of similar to 10% of the active region flux, obtained previously by the flux rope insertion method, results from the incomplete coherence of the flux rope, due to nonuniform cancellation along the polarity inversion line. A hot linear feature is observed in the active region which rises as part of the eruption and then likely traces out the field lines close to the axis of the flux rope. The flux cancellation and changing magnetic connections at one end of this feature suggest that the flux rope reaches coherence by reconnection immediately before and early in the impulsive phase of the associated flare. The sigmoid is destroyed in the eruption but reforms quickly, with the amount of cancellation involved being much smaller than in the course of its original formation.
Context. Extrapolations of solar photospheric vector magnetograms into three-dimensional magnetic fields in the chromosphere and corona are usually done under the assumption that the fields are force-free. This condition is violated in the photosphere itself and a thin layer in the lower atmosphere above. The field calculations can be improved by preprocessing the photospheric magnetograms. The intention here is to remove a non-force-free component from the data.
Aims. We compare two preprocessing methods presently in use, namely the methods of Wiegelmann et al. (2006, Sol. Phys., 233, 215) and Fuhrmann et al. (2007, A&A, 476, 349).
Methods. The two preprocessing methods were applied to a vector magnetogram of the recently observed active region NOAA AR 10 953. We examine the changes in the magnetogram effected by the two preprocessing algorithms. Furthermore, the original magnetogram and the two preprocessed magnetograms were each used as input data for nonlinear force-free field extrapolations by means of two different methods, and we analyze the resulting fields.
Results. Both preprocessing methods managed to significantly decrease the magnetic forces and magnetic torques that act through the magnetogram area and that can cause incompatibilities with the assumption of force-freeness in the solution domain. The force and torque decrease is stronger for the Fuhrmann et al. method. Both methods also reduced the amount of small-scale irregularities in the observed photospheric field, which can sharply worsen the quality of the solutions. For the chosen parameter set, the Wiegelmann et al. method led to greater changes in strong-field areas, leaving weak-field areas mostly unchanged, and thus providing an approximation of the magnetic field vector in the chromosphere, while the Fuhrmann et al. method weakly changed the whole magnetogram, thereby better preserving patterns present in the original magnetogram. Both preprocessing methods raised the magnetic energy content of the extrapolated fields to values above the minimum energy, corresponding to the potential field. Also, the fields calculated from the preprocessed magnetograms fulfill the solenoidal condition better than those calculated without preprocessing.
On utilise de plus en plus les tests de verification pour confirmer l'atteinte du consommation d'oxygene maximale (VO(2 max)). Toutefois, le moment et les methodes d'evaluation varient d'un groupe de travail a l'autre. Les objectifs de cette etude sont de constater si on peut administrer un test de verification apres un test d'effort progressif ou s'il est preferable de le faire une autre journee et si on peut determiner le VO(2 max) tout de meme lors de la premiere seance chez des sujets ne repondant pas au critere de verification. Quarante sujets (age, 24 +/- 4 ans; VO(2 max), 50 +/- 7 mL center dot min(-1)center dot kg(-1)) participent a un test d'effort progressif sur tapis roulant et, 10 min plus tard, a un test de verification (VerifDay1) a 110 % de la velocite maximale (v(max)). Le critere de verification est un VO(2) de pointe au VerifDay1 < 5,5 % a la valeur retenue au test d'effort progressif. Les sujets ne repondant pas au critere de verification passent un autre test de verification, mais a 115 % du VerifDay1', et ce, 10 min plus tard pour confirmer le VO(2) de pointe du VerifDay1 en tant que VO(2 max). Tous les autres sujets repassent le VerifDay1 a un jour different (VerifDay2). Six sujets sur quarante ne repondent pas au critere de verification. Chez quatre d'entre eux, on confirme l'atteinte du VO(2 max) au VerifDay1'. Le VO(2) de pointe au VerifDay1 est equivalent a celui du VerifDay2 (3722 +/- 991 mL center dot min(-1) comparativement a 3752 +/- 995 mL center dot min(-1), p = 0,56), mais le temps jusqu'a l'epuisement est significativement plus long au VerifDay2 (2:06 +/- 0:22 min:s comparativement a 2:42 +/- 0:38 min:s, p < 0,001, n = 34). Le VO(2) de pointe obtenu au test de verification ne semble pas conditionne par un test d'effort progressif maximal prealable. On peut donc realiser le test d'effort progressif et le test de verification lors de la meme seance d'evaluation. Chez presque tous les individus ne repondant pas au critere de verification, on peut determiner le VO(2 max) au moyen d'un autre test de verification plus intense.
Silica and silver nanoparticles are relevant materials for new applications in optics, medicine, and analytical chemistry. We have previously reported the synthesis of pH responsive, peptide-templated, chiral silver nanoparticles. The current report shows that peptide-stabilized nanoparticles can easily be coated with a silica shell by exploiting the ability of the peptide coating to hydrolyze silica precursors such as TEOS or TMOS. The resulting silica layer protects the nanoparticles from chemical etching, allows their inclusion in other materials, and renders them biocompatible. Using electron and atomic force microscopy, we show that the silica shell thickness and the particle aggregation can be controlled simply by the reaction time. Small-angle X ray scattering confirms the Ag/peptide@silica core-shell structure. UV-vis and circular dichroism spectroscopy prove the conservation of the silver nanoparticle chirality upon silicification. Biological tests show that the biocompatibility in simple bacterial systems is significantly improved once a silica layer is deposited on the silver particles.
Environmental isotope techniques, hydrogeochemical analysis and hydraulic data are employed to identify the main recharge areas of the Mt. Vulture hydrogeological basin, one of the most important aquifers of southern Italy. The groundwaters are derived from seepage of rainwater, flowing from the highest to the lowest elevations through the shallow volcanic weathered host-rock fracture zones. Samples of shallow and deep groundwater were collected at 48 locations with elevations ranging from 352 to 1,100 m above sea level (a.s.l.), for stable isotope (delta(18)O, delta D) and major ion analyses. A complete dataset of available hydraulic information has been integrated with measurements carried out in the present study. Inferred recharge elevations, estimated on the basis of the local vertical isotopic gradient of delta(18)O, range between 550 and 1,200 m a.s.l. The isotope pattern of the Quaternary aquifer reflects the spatial separation of different recharge sources. Knowledge of the local hydrogeological setting was the starting point for a detailed hydrogeochemical and isotopic study to define the recharge and discharge patterns identifying the groundwater flow pathways of the Mt. Vulture basin. The integration of all the data allowed for the tracing of the groundwater flows of the Mt. Vulture basin.
Lissencephaly is a severe brain developmental disease in human infants, which is usually caused by mutations in either of two genes, LIS1 and DCX. These genes encode proteins interacting with both the microtubule and the actin systems. Here, we review the implications of data on Dictyostelium LIS1 for the elucidation of LIS1 function in higher cells and emphasize the role of LIS1 and nuclear envelope proteins in nuclear positioning, which is also important for coordinated cell migration during neocortical development. Furthermore, for the first time we characterize Dictyostelium DCX, the only bona fide orthologue of human DCX outside the animal kingdom. We show that DCX functionally interacts with LIS1 and that both proteins have a cytoskeleton-independent function in chemotactic signaling during development. Dictyostelium LIS1 is also required for proper attachment of the centrosome to the nucleus and, thus, nuclear positioning, where the association of these two organelles has turned out to be crucial. It involves not only dynein and dynein-associated proteins such as LIS1 but also SUN proteins of the nuclear envelope. Analyses of Dictyostelium SUN1 mutants have underscored the importance of these proteins for the linkage of centrosomes and nuclei and for the maintenance of chromatin integrity. Taken together, we show that Dictyostelium amoebae, which provide a well-established model to study the basic aspects of chemotaxis, cell migration and development, are well suited for the investigation of the molecular and cell biological basis of developmental diseases such as lissencephaly.
Our goal was to reconstruct the late eighteenth century forest vegetation of the Prignitz region (NE Germany) at a scale of 1:50,000. We also wanted to relate the historical forest vegetation to the actual and potential natural vegetation. For these purposes, we selected 15 woody species and transferred relevant data found in historical records from various sources together with the recent localities of (very) old individuals belonging to these woody species into ArcView GIS. Following multi-step data processing including the generation of a point density layer using a moving window with kernel estimation and derivation of vegetation units applying Boolean algebra rules together with information on site conditions, we derived 17 forest communities corresponding to the potential natural vegetation. We were able to reconstruct the historical forest vegetation for 90% of the forest area ca. 1780. Only two of the 17 forest communities covered large parts of the forested area. The oak forest with Agrostis capillaris covered about 44% of the total forest area, and alder forests on fenland made up about 37%. Oak-hornbeam forests with Stellaria holostea comprised slightly less than 6% of the forest area, while all other forest communities comprised less than 1%. The historical forest vegetation is more similar to the potential forest vegetation and quite different from the actual forest vegetation because coniferous tree species currently cover approximately two-thirds of the actual forest area. The most beneficial result of this study is the map of high-resolution historical vegetation units that may serve as the basis for various further studies, e.g., modelling long-term changes in biodiversity at the landscape scale.
Bayesian networks are a powerful and increasingly popular tool for reasoning under uncertainty, offering intuitive insight into (probabilistic) data-generating processes. They have been successfully applied to many different fields, including bioinformatics. In this paper, Bayesian networks are used to model the joint-probability distribution of selected earthquake, site, and ground-motion parameters. This provides a probabilistic representation of the independencies and dependencies between these variables. In particular, contrary to classical regression, Bayesian networks do not distinguish between target and predictors, treating each variable as random variable. The capability of Bayesian networks to model the ground-motion domain in probabilistic seismic hazard analysis is shown for a generic situation. A Bayesian network is learned based on a subset of the Next Generation Attenuation (NGA) dataset, using 3342 records from 154 earthquakes. Because no prior assumptions about dependencies between particular parameters are made, the learned network displays the most probable model given the data. The learned network shows that the ground-motion parameter (horizontal peak ground acceleration, PGA) is directly connected only to the moment magnitude, Joyner-Boore distance, fault mechanism, source-to-site azimuth, and depth to a shear-wave horizon of 2: 5 km/s (Z2.5). In particular, the effect of V-S30 is mediated by Z2.5. Comparisons of the PGA distributions based on the Bayesian networks with the NGA model of Boore and Atkinson (2008) show a reasonable agreement in ranges of good data coverage.
A business process is a set of steps designed to be executed in a certain order to achieve a business value. Such processes are often driven by and documented using process models. Nowadays, process models are also applied to drive process execution. Thus, correctness of business process models is a must. Much of the work has been devoted to check general, domain-independent correctness criteria, such as soundness. However, business processes must also adhere to and show compliance with various regulations and constraints, the so-called compliance requirements. These are domain-dependent requirements.
In many situations, verifying compliance on a model level is of great value, since violations can be resolved in an early stage prior to execution. However, this calls for using formal verification techniques, e.g., model checking, that are too complex for business experts to apply. In this paper, we utilize a visual language. BPMN-Q to express compliance requirements visually in a way similar to that used by business experts to build process models. Still, using a pattern based approach, each BPMN-Qgraph has a formal temporal logic expression in computational tree logic (CTL). Moreover, the user is able to express constraints, i.e., compliance rules, regarding control flow and data flow aspects. In order to provide valuable feedback to a user in case of violations, we depend on temporal logic querying approaches as well as BPMN-Q to visually highlight paths in a process model whose execution causes violations.
Repression and sensitization as situational modes of coping with anxiety were examined as predictors of trait measures of cognitive avoidance and vigilance. In this study, 303 undergraduates saw a violent film clip to elicit anxiety. Increases in skin conductance level (SCL) and state anxiety (STA) from baseline were measured to identify repressors (high SCL, low STA) and contrast them with sensitizers (low SCL, high STA) and genuinely low anxious individuals (low SCL, low STA). State anger was also recorded. Trait measures of vigilance and cognitive avoidance were collected 2 weeks earlier. Significant SCL x STA interactions indicated that repressors scored higher on cognitive avoidance and lower on vigilance compared to sensitizers and low anxious participants. Repressors were less likely than sensitizers to report gaze avoidance during the clip. The anger by SCL interaction was nonsignificant, suggesting that repressors and sensitizers differ specifically in the processing of anxiety rather than negative affect in general.
The star zeta Ophiuchi is one of the brightest massive stars in the northern hemisphere and was intensively studied in various wavelength domains. The currently available observational material suggests that certain observed phenomena are related to the presence of a magnetic field. We acquired spectropolarimetric observations of zeta Oph with FORS 1 mounted on the 8-m Kueyen telescope of the VLT to investigate if a magnetic field is indeed present in this star. Using all available absorption lines, we detect a mean longitudinal magnetic field < B(z)>(all) = 141 +/- 45 G, confirming the magnetic nature of this star. We review the X-ray properties of zeta Oph with the aim to understand whether the X-ray emission of zeta Oph is dominated by magnetic or by wind instability processes.
Borehole logs provide in situ information about the fluctuations of petrophysical properties with depth and thus allow the characterization of the crustal heterogeneities. A detailed investigation of these measurements may lead to extract features of the geological media. In this study, we suggest a regularity analysis based on the continuous wavelet transform to examine sonic logs data. The description of the local behavior of the logs at each depth is carried out using the local Hurst exponent estimated by two (02) approaches: the local wavelet approach and the average-local wavelet approach. Firstly, a synthetic log, generated using the random midpoints displacement algorithm, is processed by the regularity analysis. The obtained Hurst curves allowed the discernment of the different layers composing the simulated geological model. Next, this analysis is extended to real sonic logs data recorded at the Kontinentales Tiefbohrprogramm (KTB) pilot borehole (Continental Deep Drilling Program, Germany). The results show a significant correlation between the estimated Hurst exponents and the lithological discontinuities crossed by the well. Hence, the Hurst exponent can be used as a tool to characterize underground heterogeneities.
Wildflower harvesting is an economically important activity of which the ecological effects are poorly understood. We assessed how harvesting of flowers affects shrub persistence and abundance at multiple spatial extents. To this end, we built a process-based model to examine the mean persistence and abundance of wild shrubs whose flowers are subject to harvest (serotinous Proteaceae in the South African Cape Floristic Region). First, we conducted a general sensitivity analysis of how harvesting affects persistence and abundance at nested spatial extents. For most spatial extents and combinations of demographic parameters, persistence and abundance of flowering shrubs decreased abruptly once harvesting rate exceeded a certain threshold. At larger extents, metapopulations supported higher harvesting rates before their persistence and abundance decreased, but persistence and abundance also decreased more abruptly due to harvesting than at smaller extents. This threshold rate of harvest varied with species' dispersal ability, maximum reproductive rate, adult mortality, probability of extirpation or local extinction, strength of Allee effects, and carrying capacity. Moreover, spatial extent interacted with Allee effects and probability of extirpation because both these demographic properties affected the response of local populations to harvesting more strongly than they affected the response of metapopulations. Subsequently, we simulated the effects of harvesting on three Cape Floristic Region Proteaceae species and found that these species reacted differently to harvesting, but their persistence and abundance decreased at low rates of harvest. Our estimates of harvesting rates at maximum sustainable yield differed from those of previous investigations, perhaps because researchers used different estimates of demographic parameters, models of population dynamics, and spatial extent than we did. Good demographic knowledge and careful identification of the spatial extent of interest increases confidence in assessments and monitoring of the effects of harvesting. Our general sensitivity analysis improved understanding of harvesting effects on metapopulation dynamics and allowed qualitative assessment of the probability of extirpation of poorly studied species.
One of the goals of artificial intelligence is to develop agents that learn and act in complex environments. Realistic environments typically feature a variable number of objects, relations amongst them, and non-deterministic transition behavior. While standard probabilistic sequence models provide efficient inference and learning techniques for sequential data, they typically cannot fully capture the relational complexity. On the other hand, statistical relational learning techniques are often too inefficient to cope with complex sequential data. In this paper, we introduce a simple model that occupies an intermediate position in this expressiveness/efficiency trade-off. It is based on CP-logic (Causal Probabilistic Logic), an expressive probabilistic logic for modeling causality. However, by specializing CP-logic to represent a probability distribution over sequences of relational state descriptions and employing a Markov assumption, inference and learning become more tractable and effective. Specifically, we show how to solve part of the inference and learning problems directly at the first-order level, while transforming the remaining part into the problem of computing all satisfying assignments for a Boolean formula in a binary decision diagram. We experimentally validate that the resulting technique is able to handle probabilistic relational domains with a substantial number of objects and relations.
In this paper we consider masking of unknowns (X-values) for VLSI circuits. We present a new hierarchical method of X-masking which is a major improvement of the method proposed in [4], called WIDE1. By the method proposed, the number of observable scan cells is optimized and data volume for X-masking can be significantly reduced in comparison to WIDEL This is demonstrated for three industrial designs. In cases where all X-values have to be masked the novel approach is especially efficient.
Biomaterials are used in regenerative medicine for induced autoregeneration and tissue engineering. This is often challenging, however, due to difficulties in tailoring and controlling the respective material properties. Since functionalization is expected to offer better control, in this study gelatin chains were modified with physically interacting groups based on tyrosine with the aim of causing the formation of physical crosslinks. This method permits application-specific properties like swelling and better tailoring of mechanical properties. The design of the crosslink strategy was supported by molecular dynamic (MD) simulations of amorphous bulk models for gelatin and functionalized gelatins at different water contents (0.8 and 25 wt.-%). The results permitted predictions to be formulated about the expected crosslink density and its influence on equilibrium swelling behavior and on elastic material properties. The models of pure gelatin were used to validate the strategy by comparison between simulated and experimental data such as density, backbone conformation angle distribution, and X-ray scattering spectra. A key result of the simulations was the prediction that increasing the number of aromatic functions attached to the gelatin chain leads to an increase in the number of physical netpoints observed in the simulated bulk packing models. By comparison with the Flory-Rehner model, this suggested reduced equilibrium swelling of the functionalized materials in water, a prediction that was subsequently confirmed by our experimental work. The reduction and control of the equilibrium degree of swelling in water is a key criterion for the applicability of functionalized gelatins when used, for example, as matrices for induced autoregeneration of tissues.
Langmuir monolayer degradation (LMD) experiments with polymers possessing outstanding biomedical application potential yield information regarding the kinetics of their hydrolytic or enzymatic chain scission under well-defined and adjustable degradation conditions. A brief review is given of LMD investigations, including the author's own work on 2-dimensional (2D) polymer systems, providing chain scission data, which are not disturbed by simultaneously occurring transport phenomena, such as water penetration into the sample or transport of scission fragments out of the sample.
A knowledge-based approach for the description and simulation of polymer hydrolytic and enzymatic degradation based on a combination of fast LMD experiments and computer simulation of the water penetration is briefly introduced. Finally, the advantages and disadvantages of this approach are discussed.
One of the key challenges in the context of local site effect studies is the determination of frequencies where the shakeability of the ground is enhanced. In this context, the H/V technique has become increasingly popular and peak frequencies of H/V spectral ratio are sometimes interpreted as resonance frequencies of the transmission response. In the present study, assuming that Rayleigh surface wave is dominant in H/V spectral ratio, we analyse theoretically under which conditions this may be justified and when not. We focus on 'layer over half-space' models which, although seemingly simple, capture many aspects of local site effects in real sedimentary structures. Our starting point is the ellipticity of Rayleigh waves. We use the exact formula of the H/V-ratio presented by Malischewsky & Scherbaum (2004) to investigate the main characteristics of peak and trough frequencies. We present a simple formula illustrating if and where H/V-ratio curves have sharp peaks in dependence of model parameters. In addition, we have constructed a map, which demonstrates the relation between the H/V-peak frequency and the peak frequency of the transmission response in the domain of the layer's Poisson ratio and the impedance contrast. Finally, we have derived maps showing the relationship between the H/V-peak and trough frequency and key parameters of the model such as impedance contrast. These maps are seen as diagnostic tools, which can help to guide the interpretation of H/V spectral ratio diagrams in the context of site effect studies.
In Czech, German, and many other languages, part of the semantic focus of the utterance can be moved to the left periphery of the clause. The main generalization is that only the leftmost accented part of the semantic focus can be moved. We propose that movement to the left periphery is generally triggered by an unspecific edge feature of C (Chomsky 2008) and its restrictions can be attributed to requirements of cyclic linearization, modifying the theory of cyclic linearization developed by Fox and Pesetsky (2005). The crucial assumption is that structural accent is a direct consequence of being linearized at merge, thus it is indirectly relevant for (locality restrictions on) movement. The absence of structural accent correlates with givenness. Given elements may later receive (topic or contrastive) accents, which accounts for fronting in multiple focus/contrastive topic constructions. Without any additional assumptions, the model can account for movement of pragmatically unmarked elements to the left periphery ('formal fronting', Frey 2005). Crucially, the analysis makes no reference at all to concepts of information structure in the syntax, in line with the claim of Chomsky (2008) that UG specifies no direct link between syntax and information structure.
Quantum correlations exhibit behaviour that cannot be resolved with a local hidden variable picture of the world. In quantum information, they are also used as resources for information processing tasks, such as measurement-based quantum computation (MQC). In MQC, universal quantum computation can be achieved via adaptive measurements on a suitable entangled resource state. In this paper, we look at a version of MQC in which we remove the adaptivity of measurements and aim to understand what computational abilities remain in the resource. We show that there are explicit connections between this model of computation and the question of non-classicality in quantum correlations. We demonstrate this by focusing on deterministic computation of Boolean functions, in which natural generalizations of the Greenberger-Horne-Zeilinger paradox emerge; we then explore probabilistic computation via, which multipartite Bell inequalities can be defined. We use this correspondence to define families of multi-party Bell inequalities, which we show to have a number of interesting contrasting properties.
YedY from Escherichia coil is a new member of the sulfite oxidase family of molybdenum cofactor (Moco)-containing oxidoreductases. We investigated the atomic structure of the molybdenum site in YedY by X-ray absorption spectroscopy, in comparison to human sulfite oxidase (hSO) and to a Mo(IV) model complex. The K-edge energy was indicative of Mo(V) in YedY, in agreement with X- and Q-band electron paramagnetic resonance results, whereas the hSO protein contained Mo(VI). In YedY and hSO, molybdenum is coordinated by two sulfur ligands from the molybdopterin ligand of the Moco, one thiolate sulfur of a cysteine (average Mo-S bond length of similar to 2.4 angstrom), and one (axial) oxo ligand (Mo=O, similar to 1.7 angstrom). hSO contained a second oxo group at Mo as expected, but in YedY, two species in about a 1:1 ratio were found at the active site, corresponding to an equatorial Mo-OH bond (similar to 2.1 angstrom) or possibly to a shorter M-O(-) bond. Yet another oxygen (or nitrogen) at a similar to 2.6 angstrom distance to Mo in YedY was identified, which could originate from a water molecule in the substrate binding cavity or from an amino acid residue close to the molybdenum site, i.e., Glu104, that is replaced by a glycine in hSO, or Asn45. The addition of the poor substrate dimethyl sulfoxide to YedY left the molybdenum coordination unchanged at high pH. In contrast, we found indications that the better substrate trimethylamine N-oxide and the substrate analogue acetone were bound at a similar to 2.6 angstrom distance to the molybdenum, presumably replacing the equatorial oxygen ligand. These findings were used to interpret the recent crystal structure of YedY and bear implications for its catalytic mechanism.
We have used x-ray waveguides as highly confining optical elements for nanoscale imaging of unstained biological cells using the simple geometry of in-line holography. The well-known twin-image problem is effectively circumvented by a simple and fast iterative reconstruction. The algorithm which combines elements of the classical Gerchberg-Saxton scheme and the hybrid-input-output algorithm is optimized for phase-contrast samples, well-justified for imaging of cells at multi-keV photon energies. The experimental scheme allows for a quantitative phase reconstruction from a single holographic image without detailed knowledge of the complex illumination function incident on the sample, as demonstrated for freeze-dried cells of the eukaryotic amoeba Dictyostelium discoideum. The accessible resolution range is explored by simulations, indicating that resolutions on the order of 20 nm are within reach applying illumination times on the order of minutes at present synchrotron sources.
We report explicitly time-dependent coupled cluster singles doubles (TD-CCSD) calculations, which simulate the laser-driven correlated many-electron dynamics in molecular systems. Small molecules, i.e., HF, H(2)O, NH(3), and CH(4), are treated mostly with polarized valence double zeta basis sets. We determine the coupled cluster ground states by imaginary time propagation for these molecules. Excited state energies are obtained from the Fourier transform of the time-dependent dipole moment after an ultrashort, broadband laser excitation. The time-dependent expectation values are calculated from the complex cluster amplitudes using the corresponding configuration interaction singles doubles wave functions. Also resonant laser excitations of these excited states are simulated, in order to explore the limits for the numerical stability of our current TD-CCSD implementation, which uses time-independent molecular orbitals to form excited configurations.
The iron-containing ionic liquids 1-butyl-3-methylimidazolium tetrachloroferrate(III) [C(4)mim][FeCl4] and 1-dodecyl-3-methylimidazolium tetrachloroferrate(III) [C(12)mim][FeCl4] exhibit a thermally induced demixing with water (thermomorphism). The phase separation temperature varies with IL weight fraction in water and can be tuned between 100 degrees C and room temperature. The reversible lower critical solution temperature (LCST) is only observed at IL weight fractions below ca. 35% in water. UV/Vis, IR, and Raman spectroscopy along with elemental analysis prove that the yellow-brown liquid phase recovered after phase separation is the starting IL [C(4)mim][FeCl4] and [C(12)mim][FeCl4], respectively. Photometry and ICP-OES show that about 40% of iron remains in the water phase upon phase separation. Although the process is thus not very efficient at the moment, the current approach is the first example of an LCST behavior of a metal-containing IL and therefore, although still inefficient, a prototype for catalyst removal or metal extraction.
Tectonic and metamorphic data for the Central Alps (Switzerland/Italy) are used to discuss this classic example of a Barrovian metamorphic terrain, notably the evolution of its thermal structure in space and time. Available P-T-t data indicate variable contributions of advective and conductive heat transport during collision and subsequent cooling and exhumation. Some areas experienced a prolonged period of partial melting while other areas, at the same time, show but moderate heating. The Barrow-type metamorphic field gradient observed in the final orogen is the result of two distinct tectonic processes, with their related advective and conductive heat transport processes. The two tectonic processes are (1) accretion of material within a subduction channel related to decompression and emplacement of high-pressure units in the middle crust and (2) wedging and related nappe formation in the continental lower plate. The second process postdates the first one. Wedging and underthrusting of continental lower plate material produces heat input into lower crustal levels, and this process is responsible for predominantly conductive heat transport in the overlying units. The interacting processes lead to different maximum temperatures at different times, producing the final Barrovian metamorphic field gradient. The south experienced rapid cooling, whereas the north shows moderate cooling rates. This discrepancy principally reflects differences in the temperature distribution in the deeper crust prior to cooling. Differences in the local thermal gradient that prevailed before the cooling also determined the relationships between cooling rate and exhumation rate in the different areas. Citation: Berger, A., S. M. Schmid, M. Engi, R. Bousquet, and M. Wiederkehr (2011), Mechanisms of mass and heat transport during Barrovian metamorphism: A discussion based on field evidence from the Central Alps (Switzerland/northern Italy), Tectonics, 30, TC1007, doi:10.1029/2009TC002622.
In this paper we evaluate different methods to predict soil erosion processes. We derived different layers of predictor variables for the study area in the Northern Chianti, Italy, describing the soil-lithologic complex, land use, and topographic characteristics. For a subcatchment of the Orme River, we mapped erosion processes by interpreting aerial photographs and field observations. These were classified as erosional response units (ERU), i.e. spatial areas of homogeneous erosion processes. The ERU were used as the response variable in the soil erosion modelling process. We applied two models i) bootstrap aggregation (Random Forest: RF), and ii) stochastic gradient boosting (TreeNet: TN) to predict the potential spatial distribution of erosion processes for the entire Orme River catchment. The models are statistically evaluated using training data and a set of performance parameters such as the area under the receiver operating characteristic curve (AUC), Cohen's Kappa, and pseudo R2. Variable importance and response curves provide further insight into controlling factors of erosion. Both models provided good performance in terms of classification and calibration; however, TN outperformed RF. Similar classes such as active and inactive landslides can be discriminated and well interpreted by considering response curves and relative variable importance. The spatial distribution of the predicted erosion susceptibilities generally follows topographic constraints and is similar for both models. Hence, the model-based delineation of ERU on the basis of soil and terrain information is a valuable tool in geomorphology; it provides insights into factors controlling erosion processes and may allow the extrapolation and prediction of erosion processes in unsurveyed areas.
Introducing multicomponent reactions to polymer science passerini reactions of renewable monomers
(2011)
Combination of the Passerini three component-reaction (3CR) and olefin metathesis led to the formation of poly[1-(alkyl carbamoyl)alkyl alkanoates], a new class of polyesters with amide moieties in their side chain, from renewable resources. Two different approaches were studied and compared to each other. First, monomers were synthesized by the Passerini-3CR and then polymerized via acyclic diene metathesis. Alternatively, bifunctional monomers were synthesized by self-metathesis and then polymerized by Passerini-3CR. Both approaches led to the formation of high-molecular-weight polymers. Moreover, Passerini-3CRs were shown to be a versatile grafting-onto method. The results clearly demonstrate that the Passerini-3CR offers an interesting new access to monomers and polymers and thus broadens the synthetic portfolio of polymer science.
Severely negative Delta(14)C anomalies from the mid-depth Pacific and the Arabian Sea have been taken as support for the hypothesized deglacial release of a previously isolated, extremely (14)C-deplete deep ocean carbon reservoir. We report box model simulations that cast doubt on both the existence of the hypothesized deep reservoir and its ability to explain the mid-depth Delta(14)C anomalies. First, the degree of ice age isolation needed to substantially reduce the deep Delta(14)C of the deep reservoir causes anoxia and the trapping of alkalinity from CaCO(3) dissolution, the latter increasing atmospheric CO(2). Second, even with a completely (14)C-free deep reservoir, achieving the mid-depth Delta(14)C anomalies of observed duration requires ad hoc stifling of aspects of deep circulation to prevent rapid dissipation of the anomalous (14)C-free carbon to the rest of the ocean and the atmosphere. We suggest that the mid-depth anomalies do not record basin-scale Delta(14)C changes but are instead local phenomena.
To characterize a destruction of Anderson localization by nonlinearity, we study the spreading behavior of initially localized states in disordered, strongly nonlinear lattices. Due to chaotic nonlinear interaction of localized linear or nonlinear modes, energy spreads nearly subdiffusively. Based on a phenomenological description by virtue of a nonlinear diffusion equation, we establish a one-parameter scaling relation between the velocity of spreading and the density, which is confirmed numerically. From this scaling it follows that for very low densities the spreading slows down compared to the pure power law.
We study the discrete nonlinear Schrodinger equation with a random potential in one dimension. It is characterized by the length, the strength of the random potential, and the field density that determines the effect of nonlinearity. Following the time evolution of the field and calculating the largest Lyapunov exponent, the probability of the system to be regular is established numerically and found to be a scaling function of the parameters. This property is used to calculate the asymptotic properties of the system in regimes beyond our computational power.
Three-dimensional hydrostratigraphic models from ground-penetrating radar and direct-push data
(2011)
Three-dimensional models of hydraulic conductivity and porosity are essential to understand and simulate groundwater flow in heterogeneous geological environments. However, considering the inherent limitations of traditional hydrogeological field methods in terms of resolution, alternative field approaches are needed to establish such 3-D models with sufficient accuracy. In this study, we developed a workflow combining 3-D structural information extracted from ground penetrating radar (GPR) images with 1-D in situ physical-property estimates from direct-push (DP) logging to construct a 3-D hydrostratigraphic model. To illustrate this workflow, we collected an similar to 70 m x 90 m 100 MHz 3-D GPR data set over a shallow sedimentary aquifer system resolving six different GPR facies down to similar to 15 m depth. DP logs of the relative dielectric permittivity, the relative hydraulic conductivity, the cone resistance, the sleeve friction and the pore pressure provided crucial data (1) to establish a GPR velocity model for 3-D depth migration and to check the time-to-depth conversion of the GPR data, and (2) to construct a 3-D hydrostratigraphic model. This model was built by assigning porosity values, which were computed from the DP relative dielectric permittivity logs, and DP relative hydraulic conductivity estimates to the identified GPR facies. We conclude that the integration of 3-D GPR structural images and 1-D DP logs of target physical parameters provides an efficient way for detailed 3-D subsurface characterization as needed, for example, for groundwater flow simulations.
Phylogenetic analyses using genome-scale data sets must confront incongruence among gene trees, which in plants is exacerbated by frequent gene duplications and losses. Gene tree parsimony (GTP) is a phylogenetic optimization criterion in which a species tree that minimizes the number of gene duplications induced among a set of gene trees is selected. The run time performance of previous implementations has limited its use on large-scale data sets. We used new software that incorporates recent algorithmic advances to examine the performance of GTP on a plant data set consisting of 18,896 gene trees containing 510,922 protein sequences from 136 plant taxa (giving a combined alignment length of >2.9 million characters). The relationships inferred from the GTP analysis were largely consistent with previous large-scale studies of backbone plant phylogeny and resolved some controversial nodes. The placement of taxa that were present in few gene trees generally varied the most among GTP bootstrap replicates. Excluding these taxa either before or after the GTP analysis revealed high levels of phylogenetic support across plants. The analyses supported magnoliids sister to a eudicot + monocot clade and did not support the eurosid I and II clades. This study presents a nuclear genomic perspective on the broad-scale phylogenic relationships among plants, and it demonstrates that nuclear genes with a history of duplication and loss can be phylogenetically informative for resolving the plant tree of life.
Controversy about the current state and future evolution of Himalayan glaciers has been stirred up by erroneous statements in the fourth report by the Intergovernmental Panel on Climate Change(1,2). Variable retreat rates(3-6) and a paucity of glacial mass-balance data(7,8) make it difficult to develop a coherent picture of regional climate-change impacts in the region. Here, we report remotely-sensed frontal changes and surface velocities from glaciers in the greater Himalaya between 2000 and 2008 that provide evidence for strong spatial variations in glacier behaviour which are linked to topography and climate. More than 65% of the monsoon-influenced glaciers that we observed are retreating, but heavily debris-covered glaciers with stagnant low-gradient terminus regions typically have stable fronts. Debris-covered glaciers are common in the rugged central Himalaya, but they are almost absent in subdued landscapes on the Tibetan Plateau, where retreat rates are higher. In contrast, more than 50% of observed glaciers in the westerlies-influenced Karakoram region in the northwestern Himalaya are advancing or stable. Our study shows that there is no uniform response of Himalayan glaciers to climate change and highlights the importance of debris cover for understanding glacier retreat, an effect that has so far been neglected in predictions of future water availability(9,10) or global sea level(11).
ORS1, an H2O2-Responsive NAC Transcription Factor, Controls Senescence in Arabidopsis thaliana
(2011)
We report here that ORS1, a previously uncharacterized member of the NAC transcription factor family, controls leaf senescence in Arabidopsis thaliana. Overexpression of ORS1 accelerates senescence in transgenic plants, whereas its inhibition delays it. Genes acting downstream of ORS1 were identified by global expression analysis using transgenic plants producing dexamethasone-inducible ORS1-GR fusion protein. Of the 42 up-regulated genes, 30 (similar to 70%) were previously shown to be up-regulated during age-dependent senescence. We also observed that 32 (similar to 76%) of the ORS1-dependent genes were induced by long-term (4 d), but not short-term (6 h) salinity stress (150 mM NaCl). Furthermore, expression of 16 and 24 genes, respectively, was induced after 1 and 5 h of treatment with hydrogen peroxide (H2O2), a reactive oxygen species known to accumulate during salinity stress. ORS1 itself was found to be rapidly and strongly induced by H2O2 treatment in both leaves and roots. Using in vitro binding site selection, we determined the preferred binding motif of ORS1 and found it to be present in half of the ORS1-dependent genes. ORS1 is a paralog of ORE1/ANAC092/AtNAC2, a previously reported regulator of leaf senescence. Phylogenetic footprinting revealed evolutionary conservation of the ORS1 and ORE1 promoter sequences in different Brassicaceae species, indicating strong positive selection acting on both genes. We conclude that ORS1, similarly to ORE1, triggers expression of senescence-associated genes through a regulatory network that may involve cross-talk with salt- and H2O2-dependent signaling pathways.
The Western Alpine Sesia-Lanzo Zone (SLZ) is a sliver of eclogite-facies continental crust exhumed from mantle depths in the hanging wall of a subducted oceanic slab. Eclogite-facies felsic and basic rocks sampled across the internal SLZ show different degrees of retrograde metamorphic overprint associated with fluid influx. The weakly deformed samples preserve relict eclogite-facies mineral assemblages that show partial fluid-induced compositional re-equilibration along grain boundaries, brittle fractures and other fluid pathways. Multiple fluid influx stages are indicated by replacement of primary omphacite by phengite, albitic plagioclase and epidote as well as partial re-equilibration and/or overgrowths in phengite and sodic amphibole, producing characteristic step-like compositional zoning patterns. The observed textures, together with the map-scale distribution of the samples, suggest open-system, pervasive and reactive fluid flux across large rock volumes above the subducted slab. Thermodynamic modelling indicates a minimum amount of fluid of 0 center dot 1-0 center dot 5 wt % interacting with the wall-rocks. Phase relations and reaction textures indicate mobility of K, Ca, Fe and Mg, whereas Al is relatively immobile in these medium-temperature-high-pressure fluids. Furthermore, the thermodynamic models show that recycling of previously fractionated material, such as in the cores of garnet porphyroblasts, largely controls the compositional re-equilibration of the exhumed rock body.
In high-value sweet cherry (Prunus avium), the red coloration - determined by the anthocyanins content - is correlated with the fruit ripeness stage and market value. Non-destructive spectroscopy has been introduced in practice and may be utilized as a tool to assess the fruit pigments in the supply chain processes. From the fruit spectrum in the visible (Vis) wavelength range, the pigment contents are analyzed separately at their specific absorbance wavelengths.
A drawback of the method is the need for re-calibration due to varying optical properties of the fruit tissue. In order to correct for the scattering differences, most often the spectral intensity in the visible spectrum is normalized by wavelengths in the near infrared (NIR) range, or pre-processing methods are applied in multivariate calibrations.
In the present study, the influence of the fruit scattering properties on the Vis/NIR fruit spectrum were corrected by the effective pathlength in the fruit tissue obtained from time-resolved readings of the distribution of time-of-flight (DTOF). Pigment analysis was carried out according to Lambert-Beer law, considering fruit spectral intensities, effective pathlength, and refractive index. Results were compared to commonly applied linear color and multivariate partial least squares (PLS) regression analysis. The approaches were validated on fruits at different ripeness stages, providing variation in the scattering coefficient and refractive index exceeding the calibration sample set.
In the validation, the measuring uncertainty of non-destructively analyzing fruits with Vis/NIR spectra by means of PLS or Lambert-Beer in comparison with combined application of Vis/NIR spectroscopy and DTOF measurements showed a dramatic bias reduction as well as enhanced coefficients of determination when using both, the spectral intensities and apparent information on the scattering influence by means of DTOF readings. Corrections for the refractive index did not render improved results.
1. Worldwide, the floristic composition of temperate forests bears the imprint of past land use for decades to centuries as forests regrow on agricultural land. Many species, however, display significant interregional variation in their ability to (re)colonize post-agricultural forests. This variation in colonization across regions and the underlying factors remain largely unexplored.
2. We compiled data on 90 species and 812 species x study combinations from 18 studies across Europe that determined species' distribution patterns in ancient (i.e. continuously forested since the first available land use maps) and post-agricultural forests. The recovery rate (RR) of species in each landscape was quantified as the log-response ratio of the percentage occurrence in post-agricultural over ancient forest and related to the species-specific life-history traits and local (soil characteristics and light availability) and regional factors (landscape properties as habitat availability, time available for colonization, and climate).
3. For the herb species, we demonstrate a strong (interactive) effect of species' life-history traits and forest habitat availability on the RR of post-agricultural forest. In graminoids, however, none of the investigated variables were significantly related to the RR.
4. The better colonizing species that mainly belonged to the short-lived herbs group showed the largest interregional variability. Their recovery significantly increased with the amount of forest habitat within the landscape, whereas, surprisingly, the time available for colonization, climate, soil characteristics and light availability had no effect.
5. Synthesis. By analysing 18 independent studies across Europe, we clearly showed for the first time on a continental scale that the recovery of short-lived forest herbs increased with the forest habitat availability in the landscape. Small perennial forest herbs, however, were generally unsuccessful in colonizing post-agricultural forest even in relatively densely forested landscapes. Hence, our results stress the need to avoid ancient forest clearance to preserve the typical woodland flora.
Preface
(2011)
In present-day land and marine controlled-source electromagnetic (CSEM) surveys, electromagnetic fields are commonly generated using wires that are hundreds of metres long. Nevertheless, simulations of CSEM data often approximate these sources as point dipoles. Although this is justified for sufficiently large source-receiver distances, many real surveys include frequencies and distances at which the dipole approximation is inaccurate. For 1D layered media, electromagnetic (EM) fields for point dipole sources can be computed using well-known quasi-analytical solutions and fields for sources of finite length can be synthesized by superposing point dipole fields. However, the calculation of numerous point dipole fields is computationally expensive, requiring a large number of numerical integral evaluations. We combine a more efficient representation of finite-length sources in terms of components related to the wire and its end points with very general expressions for EM fields in 1D layered media. We thus obtain a formulation that requires fewer numerical integrations than the superposition of dipole fields, permits source and receiver placement at any depth within the layer stack and can also easily be integrated into 3D modelling algorithms. Complex source geometries, such as wires bent due to surface obstructions, can be simulated by segmenting the wire and computing the responses for each segment separately. We first describe our finite-length wire expressions and then present 1D and 3D examples of EM fields due to finite-length sources for typical land and marine survey geometries and discuss differences to point dipole fields.
A protected derivative of (3R, 4R)-hexa-1,5-diene-3,4-diol, a conveniently accessible C-2-symmetric building block, undergoes single or double cross metathesis with methyl acryl-ate. The cross metathesis products are amenable to stereoselective conjugate addition reactions and can be converted into either gamma-butyrolactones or gamma-lactams.
We report on the redox behaviour of the microperoxidase-11 (MP-11) which has been electrostatically immobilized in a matrix of chitosan-embedded gold nanoparticles on the surface of a glassy carbon electrode. MP-11 contains a covalently bound heme c as the redox active group that exchanges electrons with the electrode via the gold nanoparticles. Electroactive surface concentration of MP-11 at high scan rate is between 350+/-50 pmol cm(-2), which reflects a multilayer process. The formal potential (E degrees') of MP-11 in the gold nanoparticles-chitosan film was estimated to be -(267.7+/-2.9) mV at pH 7.0. The heterogeneous electron transfer rate constant (k(s)) starts at 1.21 s(-1) and levels off at 6.45 s(-1) in the scan rate range from 0.1 to 2.0 V s(-1). Oxidation and reduction of MP-11 by hydrogen peroxide and superoxide, respectively have been coupled to the direct electron transfer of MP-11.
P>Despite ample research, understanding plant spread and predicting their ability to track projected climate changes remain a formidable challenge to be confronted. We modelled the spread of North American wind-dispersed trees in current and future (c. 2060) conditions, accounting for variation in 10 key dispersal, demographic and environmental factors affecting population spread. Predicted spread rates vary substantially among 12 study species, primarily due to inter-specific variation in maturation age, fecundity and seed terminal velocity. Future spread is predicted to be faster if atmospheric CO2 enrichment would increase fecundity and advance maturation, irrespective of the projected changes in mean surface windspeed. Yet, for only a few species, predicted wind-driven spread will match future climate changes, conditioned on seed abscission occurring only in strong winds and environmental conditions favouring high survival of the farthest-dispersed seeds. Because such conditions are unlikely, North American wind-dispersed trees are expected to lag behind the projected climate range shift.
The proportion of the axial conformer increases in the ax reversible arrow eq equilibrium of cyclohexyl acetates (RCOOC(6)H(11), R reversible arrow Me, Et, iPr, tBu, CH(2)Cl, CHCl(2), CO(3). CH(2)Br, CHBr(2), CBr(3)) with the increasing size of the acyloxy substitution. The nature of this unexpected steric substituent effect, which is opposite to general stereochemical concepts, was studied by means of ab kiln MO method, accompanied by NBO and isodesmic calculations. NBO parameters seem to be good descriptors for quantitative prediction of the experimental Delta G degrees value of the title conformational equilibrium. The origin and propagation of the substituent effect of the polar substitutions (CH(2)Cl, CHCl(2), CCl(3), CH(2)Br, CHBr(2), CBr(3)) differ, however, from those of the pure alkyl (Me, Et, iPr, tBu) substitutions. The Delta G degrees value of the polar derivatives depends on the qC8 charges, on the occupation of the sigma(center dot)(C1-07) orbital and on the hyperconjugative pi(center dot)(c=O) -> sigma(center dot)(C10-X) and sigma(center dot)(C10-X) -> pi(center dot)(c=O) interactions. The substituent sensitivity of these NBC parameters for the two conformers differ to the effect that the ax reversible arrow eq equilibrium is shifted to the left side with increasing electron withdrawing character of the acyloxy group. The Delta G degrees values of the alkyl derivatives are interpreted in terms of the calculated dipole moments. The destabilization in the non-polar medium (the experimental Delta G degrees values used were measured in CD(2)Cl(2)) due to the enhanced dipolar character is more prominent in the case of the equatorial alkyl conformers. As the consequence, the ax reversible arrow eq equilibrium is shifted to the left despite the increasing size of the R group when going from Me to tBu substitution.
Understory herbs are an essential part of tropical rain forests, but little is known about factors limiting their reproduction. Many of these herbs are clonal, patchily distributed, and produce large floral displays of nectar-rich 1-d flowers to attract hummingbird pollinators that may transport pollen over long distances. The aim of this study was to investigate the effects of clonality, cross-proximity, and patchy distribution on the reproduction of the hummingbird-pollinated Amazonian herb Heliconia metallica. We experimentally pollinated flowers within populations with self-pollen and with pollen of different diversity, crossed flowers between populations, and added supplemental pollen to ramets growing solitarily or in conspecific patches. Only flowers pollinated early in the morning produced seeds. Selfed flowers produced seeds, but seed number and mass were strongly reduced, suggesting partial sterility and inbreeding depression after selfing. Because of pollen competition, flowers produced more seeds after crosses with several than with single donor plants. Crosses between populations mostly resulted in lower seed production than those within populations, suggesting outbreeding depression. Ramets in patches produced fewer seeds than solitary ramets and were more pollen-limited, possibly due to geitonogamy and biparental inbreeding in patches. We conclude that high rates of geitonogamy due to clonality and pollen limitation due to the short receptivity of flowers and patchy distribution constrain the reproduction of this clonal herb. Even in unfragmented rain forests with highly mobile pollinators, outbreeding depression may be a widespread phenomenon in plant reproduction.
A simple dip-coating technique was employed to manufacture coaxial actuators with multiple layers of alternating dielectric and conducting layers. A thin rubber string was coated with an electrode-insulator-electrode structure, giving rise to a thin, fiber-like actuator with coaxial geometry. The process was repeated to achieve a compact multilayer actuator with up to three coaxial dielectric layers. Mechanical and electromechanical characterization of the actuators is presented, showing actuation strains up to 8% and proper voltage-thickness scaling behavior. Also presented is a capacitance vs. extension plot, demonstrating that these structures can be used for compact and accurate capacitive strain sensing.
Overweight as a global problem is a challenge to the health systems today and in the future. Detailed information about the development of body composition in children can help to design preventive measures to stop this trend. In the present study 1397 German children aged 6-12 complete years were investigated with anthropometric methods (i.e. height, weight, BMI, skeleton robustness, and percentage of body fat) in 2008/09. The results were compared with a 10 years old identical study. Today, the investigated children are a little bit smaller and the range of BMI and percentage of body fat is increasing. The large decrease of the skeletal robustness especially in the 10(th) and 3(rd) percentile is important. Decrease of physical activity as the most important reason for shrinking skeletal robustness is discussed.
Objectives: Stroke, frequently a consequence of hypertension, is one of the leading causes of death and neurological disabilities worldwide. In the ischemic brain, levels of endothelin-1, one of the most potent vasoconstrictors, are raised. Anti-inflammatory and neuroprotective effects of endothelin antagonists after stroke have been described in literature. Based on these findings, we investigated the protective effect of the endothelin converting enzyme/neutral endopeptidase blocker, SLV 338, in salt-loaded, stroke-prone, spontaneously hypertensive rats.
Methods: Male, 8-week-old spontaneously hypertensive stroke-prone rats were put on a high salt diet and treated with either 30 mg/kg or 100 mg/kg SLV 338 or vehicle for 27 weeks. Blood pressure, neurological outcome, body weight, and mortality were investigated throughout treatment. In weeks 1 and 9, animals were housed in metabolic cages for collection of urinary and blood samples and assessment of salt water and food intake. In weeks 22 and 27, additional blood samples were taken. At the end of the study, all brains were analyzed using magnetic resonance imaging.
Results: SLV 338 was well tolerated in all animals. Neurological outcome and infarct size were similar in all groups. Albuminuria was considerably delayed and the incidence of stroke significantly lowered in treated animals. In spontaneously hypertensive stroke-prone rats, treatment with SLV 338 significantly (P=0.01) improved survival in comparison to the vehicle treated group in a blood pressure-independent manner.
Discussion: Our data in spontaneously hypertensive stroke-prone rats demonstrate that combined endothelin converting enzyme/neutral endopeptidase inhibition could offer a new therapeutic approach for primary stroke prevention and improvement of mortality. The mechanism seems to be blood pressure-independent.
We investigate the decidability of the operation problem for TOL languages and subclasses. Fix an operation on formal languages. Given languages from the family considered (OL languages, TOL languages, or their propagating variants), is the application of this operation to the given languages still a language that belongs to the same language family? Observe, that all the Lindenmayer language families in question are anti-AFLs, that is, they are not closed under homomorphisms, inverse homomorphisms, intersection with regular languages, union, concatenation, and Kleene closure. Besides these classical operations we also consider intersection and substitution, since the language families under consideration are not closed under these operations, too. We show that for all of the above mentioned language operations, except for the Kleene closure, the corresponding operation problems of OL and TOL languages and their propagating variants are not even semidecidable. The situation changes for unary OL languages. In this case we prove that the operation problems with respect to Kleene star, complementation, and intersection with regular sets are decidable.
Investigation of a right-laterally offset channel at the Miller's Field paleoseismic site yields a late Holocene slip rate of 26.2 +6.4/-4.3 mm/yr (1 sigma) for the main trace of the San Andreas fault at Parkfield, California. This is the first well-documented geologic slip rate between the Carrizo and creeping sections of the San Andreas fault. This rate is lower than Holocene measurements along the Carrizo Plain and rates implied by far-field geodetic measurements (similar to 35 mm/yr). However, the rate is consistent with historical slip rates, measured to the northwest, along the creeping section of the San Andreas fault (<30 mm/yr). The paleoseismic exposures at the Miller's Field site reveal a pervasive fabric of clay shear bands, oriented clockwise oblique to the San Andreas fault strike and extending into the uppermost stratigraphy. This fabric is consistent with dextral aseismic creep and observations of surface slip from the 28 September 2004 M6 Parkfield earthquake. Together, this slip rate and deformation fabric suggest that the historically observed San Andreas fault slip behavior along the Parkfield section has persisted for at least a millennium, and that significant slip is accommodated by structures in a zone beyond the main San Andreas fault trace.
The Takab complex is composed of a variety of metamorphic rocks including amphibolites, metapelites, mafic granulites, migmatites and meta-ultramafics, which are intruded by the granitoid. The granitoid magmatic activity occurred in relation to the subduction of the Neo-Tethys oceanic crust beneath the Iranian crust during Tertiary times. The granitoids are mainly granodiorite, quartz monzodiorite, monzonite and quartz diorite. Chemically, the magmatic rocks are characterized by ASI < 1.04, AI < 0.87 and high contents of CaO (up to similar to 14.5 wt %), which are consistent with the I-type magmatic series. Low FeO(t)/(FeO(t)+MgO) values (< 0.75) as well as low Nb, Y and K(2)O contents of the investigated rocks resemble the calc-alkaline series. Low SiO(2), K(2)O/Na(2)O and Al(2)O(3) accompanied by high CaO and FeO contents indicate melting of metabasites as an appropriate source for the intrusions. Negative Ti and Nb anomalies verify a metaluminous crustal origin for the protoliths of the investigated igneous rocks. These are comparable with compositions of the associated mafic migmatites, in the Takab metamorphic complex, which originated from the partial melting of amphibolites. Therefore, crustal melting and a collision-related origin for the Takab calc-alkaline intrusions are proposed here on the basis of mineralogy and geochemical characteristics. The P-T evolution during magmatic crystallization and subsolidus cooling stages is determined by the study of mineral chemistry of the granodiorite and the quartz diorite. Magmatic crystallization pressure and temperature for the quartz-diorite and the granodiorite are estimated to be P similar to 7.8 +/- 2.5 kbar, T similar to 760 +/- 75 degrees C and P similar to 5 +/- 1 kbar, T similar to 700 degrees C, respectively. Subsolidus conditions are consistent with temperatures of similar to 620 degrees C and similar to 600 degrees C, and pressures of similar to 5 kbar and similar to 3.5 kbar for the quartz-diorite and the granodiorite, respectively.
The adsorption of molecules to the surface of carbon nanostructures opens a new field of hybrid systems with distinct and controllable properties. We present a microscopic study of the optical absorption in carbon nanotubes functionalized with molecular spiropyran photoswitches. The switching process induces a change in the dipole moment leading to a significant coupling to the charge carriers in the nanotube. As a result, the absorption spectra of functionalized tubes reveal a considerable redshift of transition energies depending on the switching state of the spiropyran molecule. Our results suggest that carbon nanotubes are excellent substrates for the optical readout of spiropyran-based molecular switches. The gained insights can be applied to other noncovalently functionalized one-dimensional nanostructures in an externally induced dipole field.
Background. Endothelin 1 contributes to renal blood flow control and pathogenesis of kidney diseases. The differential effects, however, of endothelin 1 (ET-1) on afferent (AA) and efferent arterioles (EA) remain to be established.
Methods. We investigated endothelin type A and B receptor (ETA-R, ETB-R) functions in the control of AA and EA. Arterioles of ETB-R deficient, rescued mice [ETB (-/-)] and wild types [ETB(+/+)] were microperfused.
Results. ET-1 constricted AA stronger than EA in ETB (-/-) and ETB(+/+) mice. Results in AA: ET-1 induced similar constrictions in ETB(-/-) and ETB(+/+) mice. BQ-123 (ETA-R antagonist) inhibited this response in both groups. ALA-ET-1 and IRL1620 (ETB-R agonists) had no effect on arteriolar diameter. L-NAME did neither affect basal diameters nor ET-1 responses. Results in EA: ET-1 constricted EA stronger in ETB(+/+) compared to ETB(-/-). BQ-123 inhibited the constriction completely only in ETB(-/-). ALA-ET-1 and IRL1620 constricted only arterioles of ETB(+/+) mice. L-NAME decreased basal diameter in ETB(+/+), but not in ETB(-/-) mice and increased the ET-1 response similarly in both groups. The L-NAME actions indicate a contribution of ETB-R in basal nitric oxide (NO) release in EA and suggest dilatory action of ETA-R in EA.
Conclusions. ETA-R mediates vasoconstriction in AA and contributes to vasoconstriction in EA in this mouse model. ETB-R has no effect in AA but mediates basal NO release and constriction in EA. The stronger effect of ET-1 on AA supports observations of decreased glomerular filtration rate to ET-1 and indicates a potential contribution of ET-1 to the pathogenesis of kidney diseases.
Complex layered deformation within the Aegean crust and mantle revealed by seismic anisotropy
(2011)
Continental lithosphere can undergo pervasive internal deformation, often distributed over broad zones near plate boundaries. However, because of the paucity of observational constraints on three-dimensional movement at depth, patterns of flow within the lithosphere remain uncertain. Endmember models for lithospheric flow invoke deformation localized on faults or deep shear zones or, alternatively, diffuse, viscous-fluid-like flow. Here we determine seismic Rayleigh-wave anisotropy in the crust and mantle of the Aegean region, an archetypal example of continental deformation. Our data reveal a complex, depth-dependent flow pattern within the extending lithosphere. Beneath the northern Aegean Sea, fast shear wave propagation is in a North-South direction within the mantle lithosphere, parallel to the extensional component of the current strain rate field. In the south-central Aegean, where deformation is weak at present, anisotropic fabric in the lower crust runs parallel to the direction of palaeo-extension in the Miocene. The close match of orientations of regional-scale anisotropic fabric and the directions of extension during the last significant episodes of deformation implies that at least a large part of the extension in the Aegean has been taken up by distributed viscous flow in the lower crust and lithospheric mantle.
The dynamics of the North Atlantic subpolar gyre (SPG) are assessed under present and glacial boundary conditions by investigating the SPG sensitivity to surface wind-stress changes in a coupled climate model. To this end, the gyre transport is decomposed in Ekman, thermohaline, and bottom transports. Surface wind-stress variations are found to play an important indirect role in SPG dynamics through their effect on water-mass densities. Our results suggest the existence of two dynamically distinct regimes of the SPG, depending on the absence or presence of deep water formation (DWF) in the Nordic Seas and a vigorous Greenland-Scotland ridge (GSR) overflow. In the first regime, the GSR overflow is weak and the SPG strength increases with wind-stress as a result of enhanced outcropping of isopycnals in the centre of the SPG. As soon as a vigorous GSR overflow is established, its associated positive density anomalies on the southern GSR slope reduce the SPG strength. This has implications for past glacial abrupt climate changes, insofar as these can be explained through latitudinal shifts in North Atlantic DWF sites and strengthening of the North Atlantic current. Regardless of the ultimate trigger, an abrupt shift of DWF into the Nordic Seas could result both in a drastic reduction of the SPG strength and a sudden reversal in its sensitivity to wind-stress variations. Our results could provide insight into changes in the horizontal ocean circulation during abrupt glacial climate changes, which have been largely neglected up to now in model studies.
We introduce an approach to detecting inconsistencies in large biological networks by using answer set programming. To this end, we build upon a recently proposed notion of consistency between biochemical/genetic reactions and high-throughput profiles of cell activity. We then present an approach based on answer set programming to check the consistency of large-scale data sets. Moreover, we extend this methodology to provide explanations for inconsistencies by determining minimal representations of conflicts. In practice, this can be used to identify unreliable data or to indicate missing reactions.
Chitosan has several biological properties useful for the food industry, but the most attractive is its potential use as a food preservative of natural origin due to its antimicrobial activity against a wide range of food-borne microorganisms. Among food-borne pathogens, Campylobacter jejuni and related species are recognised as the most common causes of bacterial food-borne diarrhoeal disease throughout the world. Recently, it has been demonstrated that campylobacters are highly sensitive to chitosan. Even though chitosan is known to have important functional activities, poor solubility makes them difficult to use in food and biomedical applications. Unlike chitosan, the low viscosity and good solubility of chitosan oligosaccharides (COS) make them especially attractive in an important number of useful applications. In the present work, the effect of different COS on C. jejuni was investigated. Variables such as the physicochemical characteristics of chitosan and the enzyme used in COS preparation were studied. The COS had been fractioned using ultrafiltration membranes and each fraction was characterized regarding its FA and molecular weight distribution. It has been demonstrated that the biological properties of COS on Campylobacter depend on the composition of the fraction analysed. COS prepared by enzymatic hydrolysis with chitosanase were more active against Campylobacter that lysozyme-derived COS, and this behaviour seems to be related with the acetylation of the chains. On the other hand. the 10-30 kDa fraction was the most active COS fraction, independently of the enzyme used for the hydrolysis. These results have shown that COS could be useful as antimicrobial in the control of C. jejuni.
The six possible isomers of di-N-acetylchitotetraoses [AADD, ADDA, ADAD, DADA, DAAD, and DDAA, where D stands for 2-amino-2-deoxy-3-D-glucose (GlcN) and A for 2-acetamido-2-deoxy-beta-D-glucose (GlcNAc)] were analyzed by ESI(+)-MSn. Collision induced dissociation via MSn experiments were performed for the sodiated molecules of m/z 769 [M+Na](+) for each isomer, and fragments were generated mainly by glycosidic bond and cross-ring cleavages. Rules of fragmentation were then established. A reducing end D residue yields the (O.2)A(4) cross-ring [M-59+Na](+) fragment of m/z 710 as the most abundant, whereas isomers containing a reducing end A prefer to lose water to form the [M-18+Na](+) ion of m/z 751, as well as abundant (O.2)A(4) cross-ring [M-101+Na](+) fragments of m/z 668 and B-3 [M-221+Na](+) ions of m/z 548. MS3 of C- and Y-type ions shows analogous fragmentation behaviour that allows identification of the reducing end next-neighbour residue. Due to gas-phase anchimeric assistance, B-type cleavage between the glycosidic oxygen and the anomeric carbon atom is favoured when the glycon is an A residue. Relative ion abundances are generally in the order B >> C > Y, but may vary depending on the next neighbour towards the non-reducing end. These fragmentation rules were used for partial sequence analysis of hetero-chitooligosaccharides of the composition D(2)A(3), D(3)A(3), D(2)A(4), D(4)A(3), and D(3)A(4).
The purpose of this paper is to display the static strength capacities of healthy adults in different age categories. A total of 279 healthy German adults at the ages of 20 to 29 years, 50 to 59 years and 60 to 69 years generated their maximum static handgrip, index finger and thumb push strength, as well as their maximum opening strength on a smooth jar lid of 85 mm diameter and on a knurled bottle lid of 31 mm with their right hand. The results show larger male strength than female strength. Significant age-induced differences appear primarily in opening strengths between the age groups 20 to 29 and 50 to 59 years in male subjects and in female opening strengths between the age groups 20 to 29 and 60 to 69 years as well as between the age groups 50 to 59 and 60 to 69 years. Of greatest interest is that elderly men show the largest opening strengths.
A new strategy for the synthesis of high permittivity polymer composites is demonstrated based on well-defined spatial distribution of ultralow amounts of conductive nanoparticles. The spatial distribution Was realized by immobilizing Cu nanoparticles within the pore system of Alia microspheres, preventing direct contact between individual Cu particles. Both Cu-loaded and unloaded silica microspheres were-then used as fillers in polymer composites prepared with thermoplastic SEBS rubber is the matrix. With a metallic Cu content of about 0.26 vol % In the compoilte, a relative increase of 94% In real permittivity was obtained. No Cu-induced relaxations were observed in the dielectric spectrum within the studied frequency range of 0.1 Hz to 1 MHz. When related to the amount of conductive nanoparticles, the obtained composites achieve the highest broad spectrum enhancement of permittivity ever reported for a polymer based composite.
Laura Pavesi, Elvira De Matthaeis, Ralph Tiedemann, and Valerio Ketmaier (2011) Temporal population genetics and COI phylogeography of the sandhopper Macarorchestia remyi (Amphipoda: Talitridae). Zoological Studies 50(2): 220-229. In this study we assessed levels of genetic divergence and variability in 208 individuals of the supralittoral sandhopper Macarorchestia remyi, a species strictly associated with rotted wood stranded on sand beaches, by analyzing sequence polymorphisms in a fragment of the mitochondrial DNA (mtDNA) gene coding cytochrome oxidase subunit I (COI). The geographical distribution and ecology of the species are poorly known. The study includes 1 Tyrrhenian and 2 Adriatic populations sampled along the Italian peninsula plus a single individual found on Corfu Is. (Greece). The Tyrrhenian population was sampled monthly for 1 yr. Genetic data revealed a deep phylogeographic break between the Tyrrhenian and Adriatic populations with no shared haplotypes. The single individual collected on Corfu Is. carried the most common haplotype found in the Tyrrhenian population. A mismatch analysis could not reject the hypothesis of a sudden demographic expansion in almost all but 2 monthly samples. When compared to previous genetic data centered on a variety of Mediterranean talitrids, our results place M. remyi among those species with profound intraspecific divergence (sandhoppers) and dissimilar from beachfleas, which generally display little population genetic structuring.
We describe the petrographic characteristics, whole-rock geochemistry and mineral chemistry of rocks from the Pucarilla-Cerro Tipillas Volcanic Complex with emphasis on the rocks belonging to the middle Miocene Luingo caldera, located in the south-eastern portion of the Central Volcanic Zone (CVZ) of the Andes. We modelled the petrogenesis of the Luingo caldera rocks as a mixture of ca. 20% crustal magmas and 80% of mantle magmas by AFC with recharge processes. A comparison of Luingo geochemical data with the composition of Miocene-Pliocene volcanic rocks from the broad area, points to major thickening events during the middle Miocene for the western portion and during the upper Miocene for the eastern portion of the Southern CVZ. In the eastern sector (similar to 66 degrees W) the mantle source appears to change from a spinel-lherzolite type for the middle Miocene to a garnet-lherzolite type for the upper Miocene-Pliocene magmas. The areal distribution of the volcanic products led to the recognition of approximately equivalent areas covered by volcanic rocks both in the eastern and in the western Puna borders. This indicates a broad arc, which was structurally controlled at the proto-Puna/Puna margins, whose geochemical differences are related with variations in crustal thicknesses and heterogeneous mantle sources from west to east.
A common problem in ecology is identifying the relationship between relief and site properties obtainable only by point measurements. The method of Multi-Scale Landscape Analysis (MSLA) identifies such correlations. MSLA combines frequency filtering of the digital elevation model (DEM) with an estimation of the optimum filter coefficients using an optimization procedure. Tested using point data of soil decarbonation from a German young moraine landscape, MSLA provided significant results. Implemented within open source software SAMT. MSLA is comfortable and flexible to use, offering applications for numerous other spatial analysis problems.
We consider the problem of discrete time filtering (intermittent data assimilation) for differential equation models and discuss methods for its numerical approximation. The focus is on methods based on ensemble/particle techniques and on the ensemble Kalman filter technique in particular. We summarize as well as extend recent work on continuous ensemble Kalman filter formulations, which provide a concise dynamical systems formulation of the combined dynamics-assimilation problem. Possible extensions to fully nonlinear ensemble/particle based filters are also outlined using the framework of optimal transportation theory.
In this work, the adsorption and splitting of the water molecule by light and/or an external potential is investigated in the frame of (photo-) electrochemical cells using a rutile ruthenium dioxide anode. With the help of periodic density functional calculations, the adsorbed structures of H(2)O and some radicals involved in the splitting process (O, OH, OOH) are obtained and compared with the available experimental results. On the basis of these electronic-structure calculations, we use a method to calculate the stability of the reaction intermediates and conclude on the thermodynamical possibility of the water splitting reaction at the surface. We demonstrate that a moderate overpotential of 0.64 V is required for the reaction to take place at the RuO(2)(110) surface.
This review addresses the functional organization of the mammalian cochlea under a comparative and evolutionary perspective. A comparison of the monotreme cochlea with that of marsupial and placental mammals highlights important evolutionary steps towards a hearing organ dedicated to process higher frequencies and a larger frequency range than found in non-mammalian vertebrates. Among placental mammals, there are numerous cochlear specializations which relate to hearing range in adaptation to specific habitats that are superimposed on a common basic design. These are illustrated by examples of specialist ears which evolved excellent high frequency hearing and echolocation (bats and dolphins) and by the example of subterranean rodents with ears devoted to processing low frequencies. Furthermore, structural functional correlations important for tonotopic cochlear organization and predictions of hearing capabilities are discussed.
Ether functionalities form an important cross-linking structure within the macromolecular organic matrix of lignites and coals. To obtain a deeper insight into the complex internal structure of such macromolecules and the maturation related changes of the ether compounds within the network structure, boron tribromide (BBr3) ether cleavage was applied to a series of lignite and coal samples of different maturity (R-0 0.27-0.80%) obtained from coal mines and natural outcrops from the North and South Island of New Zealand. Terminal ether-bound alcohols rapidly decrease during diagenesis and occur only in low amounts during the catagenetic stage. Comparison between ester- and ether-bound terminal alcohols indicates a parallel decreasing trend during the diagenetic stage, suggesting that the stability differences between both linkages are not large enough to be observed in maturation processes over geological time scales:Polyether compounds were detected with chain length up to five carbon atoms. After a small decrease during the diagenetic phase these compounds occur in relatively high concentrations, even in the main catagenetic stage. This suggests that these linkage structures represent important cross-linking substructures within the macromolecular matrix of lignites and coals being sterically protected within the macromolecular network during the maturation process. Additional cross-linking substructures were (poly)ether aromatics, esters and ketones.
Lake Naivasha, Kenya, is one of a number of freshwater lakes in the East African Rift System. Since the beginning of the twentieth century, it has experienced greater anthropogenic influence as a result of increasingly intensive farming of coffee, tea, flowers, and other horticultural crops within its catchment. The water-level history of Lake Naivasha over the past 200 years was derived from a combination of instrumental records and sediment data. In this study, we analysed diatoms in a lake sediment core to infer past lacustrine conductivity and total phosphorus concentrations. We also measured total nitrogen and carbon concentrations in the sediments. Core chronology was established by (210)Pb dating and covered a similar to 186-year history of natural (climatic) and human-induced environmental changes. Three stratigraphic zones in the core were identified using diatom assemblages. There was a change from littoral/epiphytic diatoms such as Gomphonema gracile and Cymbella muelleri, which occurred during a prolonged dry period from ca. 1820 to 1896 AD, through a transition period, to the present planktonic Aulacoseira sp. that favors nutrient-rich waters. This marked change in the diatom assemblage was caused by climate change, and later a strong anthropogenic overprint on the lake system. Increases in sediment accumulation rates since 1928, from 0.01 to 0.08 g cm(-2) year(-1) correlate with an increase in diatom-inferred total phosphorus concentrations since the beginning of the twentieth century. The increase in phosphorus accumulation suggests increasing eutrophication of freshwater Lake Naivasha. This study identified two major periods in the lake's history: (1) the period from 1820 to 1950 AD, during which the lake was affected mainly by natural climate variations, and (2) the period since 1950, during which the effects of anthropogenic activity overprinted those of natural climate variation.
Fluid intelligence is the ability to think flexibly and to understand abstract relations. People with high fluid intelligence (hi-fluIQ) perform better in analogical reasoning tasks than people with average fluid intelligence (ave-fluIQ). Although previous neuroimaging studies reported involvement of parietal and frontal brain regions in geometric analogical reasoning (which is a prototypical task for fluid intelligence), however, neuroimaging findings on geometric analogical reasoning in hi-fluIQ are sparse. Furthermore, evidence on the relation between brain activation and intelligence while solving cognitive tasks is contradictory. The present study was designed to elucidate the cerebral correlates of geometric analogical reasoning in a sample of hi-fluIQ and ave-fluIQ high school students. We employed a geometric analogical reasoning task with graded levels of task difficulty and confirmed the involvement of the parieto-frontal network in solving this task. In addition to characterizing the brain regions involved in geometric analogical reasoning in hi-fluIQ and ave-fluIQ, we found that blood oxygenation level dependency (BOLD) signal changes were greater for hi-fluIQ than for ave-fluIQ in parietal brain regions. However, ave-fluIQ showed greater BOLD signal changes in the anterior cingulate cortex and medial frontal gyrus than hi-fluIQ. Thus, we showed that a similar network of brain regions is involved in geometric analogical reasoning in both groups. Interestingly, the relation between brain activation and intelligence is not mono-directional, but rather, it is specific for each brain region. The negative brain activation-intelligence relationship in frontal brain regions in hi-fluIQ goes along with a better behavioral performance and reflects a lower demand for executive monitoring compared to ave-fluIQ individuals. In conclusion, our data indicate that flexibly modulating the extent of regional cerebral activity is characteristic for fluid intelligence.
An efficient, reliable and low-cost procedure to determine the silicon content in plant material is presented which allows to monitor the agricultural aspects like growth and yield. The presented procedure consists of a hydrochloric acid pre-treatment and a subsequent thermal oxidation. The method is compared to other processes like dissolution in hydrofluoric acid combined with ICP OES, energy-dispersive X-ray fluorescence spectroscopy (EDXRF) or aqua regia treatment.
Morphological plasticity is a striking characteristic of plants in natural communities. In the context of foraging behavior particularly, root plasticity has been documented for numerous species. Root plasticity is known to mitigate competitive interactions by reducing the overlap of the individuals' rhizospheres. But despite its obvious effect on resource acquisition, plasticity has been generally neglected in previous empirical and theoretical studies estimating interaction intensity among plants. In this study, we developed a semi-mechanistic model that addresses this shortcoming by introducing the idea of compensatory growth into the classical-zone-of influence (ZOI) and field-of-neighborhood (FON) approaches. The model parameters describing the belowground plastic sphere of influence (PSI) were parameterized using data from an accompanying field experiment. Measurements of the uptake of a stable nutrient analogue at distinct distances to the neighboring plants showed that the study species responded plastically to belowground competition by avoiding overlap of individuals' rhizospheres. An unexpected finding was that the sphere of influence of the study species Bromus hordeaceus could be best described by a unimodal function of distance to the plant's center and not with a continuously decreasing function as commonly assumed. We employed the parameterized model to investigate the interplay between plasticity and two other important factors determining the intensity of competitive interactions: overall plant density and the distribution of individuals in space. The simulation results confirm that the reduction of competition intensity due to morphological plasticity strongly depends on the spatial structure of the competitive environment. We advocate the use of semi-mechanistic simulations that explicitly consider morphological plasticity to improve our mechanistic understanding of plant interactions.