TY - JOUR A1 - Zakharova, A. A1 - Nikoloski, Zoran A1 - Koseska, Aneta T1 - Dimensionality reduction of bistable biological systems JF - Bulletin of mathematical biology : official journal of the Society for Mathematical Biology N2 - Time hierarchies, arising as a result of interactions between system's components, represent a ubiquitous property of dynamical biological systems. In addition, biological systems have been attributed switch-like properties modulating the response to various stimuli across different organisms and environmental conditions. Therefore, establishing the interplay between these features of system dynamics renders itself a challenging question of practical interest in biology. Existing methods are suitable for systems with one stable steady state employed as a well-defined reference. In such systems, the characterization of the time hierarchies has already been used for determining the components that contribute to the dynamics of biological systems. However, the application of these methods to bistable nonlinear systems is impeded due to their inherent dependence on the reference state, which in this case is no longer unique. Here, we extend the applicability of the reference-state analysis by proposing, analyzing, and applying a novel method, which allows investigation of the time hierarchies in systems exhibiting bistability. The proposed method is in turn used in identifying the components, other than reactions, which determine the systemic dynamical properties. We demonstrate that in biological systems of varying levels of complexity and spanning different biological levels, the method can be effectively employed for model simplification while ensuring preservation of qualitative dynamical properties (i.e., bistability). Finally, by establishing a connection between techniques from nonlinear dynamics and multivariate statistics, the proposed approach provides the basis for extending reference-based analysis to bistable systems. KW - Bistability KW - Time-scales hierarchy KW - Similarity transformation KW - Canonical correlation analysis KW - Dimensionality reduction Y1 - 2013 U6 - https://doi.org/10.1007/s11538-013-9807-8 SN - 0092-8240 VL - 75 IS - 3 SP - 373 EP - 392 PB - Springer CY - New York ER - TY - JOUR A1 - Oskinova, Lida A1 - Sun, W. A1 - Evans, C. J. A1 - Henault-Brunet, V. A1 - Chu, Y.-H. A1 - Gallagher, J. S. A1 - Guerrero, Martín A. A1 - Gruendl, R. A. A1 - Güdel, M. A1 - Silich, S. A1 - Chen, Y. A1 - Naze, Y. A1 - Hainich, Rainer A1 - Reyes-Iturbide, J. T1 - Discovery of x-ray emission from young suns in the small magellanic cloud JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We report the discovery of extended X-ray emission within the young star cluster NGC 602a in the Wing of the Small Magellanic Cloud (SMC) based on observations obtained with the Chandra X-Ray Observatory. X-ray emission is detected from the cluster core area with the highest stellar density and from a dusty ridge surrounding the H II region. We use a census of massive stars in the cluster to demonstrate that a cluster wind or wind-blown bubble is unlikely to provide a significant contribution to the X-ray emission detected from the central area of the cluster. We therefore suggest that X-ray emission at the cluster core originates from an ensemble of low-and solar-mass pre-main-sequence (PMS) stars, each of which would be too weak in X-rays to be detected individually. We attribute the X-ray emission from the dusty ridge to the embedded tight cluster of the newborn stars known in this area from infrared studies. Assuming that the levels of X-ray activity in young stars in the low-metallicity environment of NGC 602a are comparable to their Galactic counterparts, then the detected spatial distribution, spectral properties, and level of X-ray emission are largely consistent with those expected from low-and solar-mass PMS stars and young stellar objects (YSOs). This is the first discovery of X-ray emission attributable to PMS stars and YSOs in the SMC, which suggests that the accretion and dynamo processes in young, low-mass objects in the SMC resemble those in the Galaxy. KW - Magellanic Clouds KW - ISM: bubbles KW - H II regions KW - stars: winds, outflows KW - stars: pre-main sequence KW - X-rays: stars Y1 - 2013 U6 - https://doi.org/10.1088/0004-637X/765/1/73 SN - 0004-637X VL - 765 IS - 1 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Kroll, Alexander T1 - The other type of performance information - nonroutine feedback, its relevance and use JF - Public administration review N2 - The literature on performance information use explains how public managers deal with mainly quantitative data that are systematically collected and formally reported. This article argues that such a narrow understanding is incomplete, as it excludes all kinds of nonroutine performance information, including verbal, ad hoc, and qualitative feedback. To understand how responsive public managers are to performance feedback, alternative sources of performance information need to be taken into account. A literature review suggests considering two important sources of nonroutine feedback: organizational insiders and relevant external stakeholders. Using survey data from German local government, this article shows that public managers prefer to use nonroutine feedback over routine data from performance reports. Furthermore, a regression analysis indicates that different sources of performance information require different determinants to trigger their use. This finding is essential because it suggests that explanations of performance information use can covary with the information source studied. Y1 - 2013 U6 - https://doi.org/10.1111/j.1540-6210.2012.02648.x SN - 0033-3352 VL - 73 IS - 2 SP - 265 EP - 276 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Speck, Janina A1 - Räuber, Christina A1 - Kükenshöner, Tim A1 - Niemöller, Christoph A1 - Mueller, Katelyn J. A1 - Schleberger, Paula A1 - Dondapati, Padmarupa A1 - Hecky, Jochen A1 - Arndt, Katja Maren A1 - Müller, Kristian M. T1 - TAT hitchhiker selection expanded to folding helpers, multimeric interactions and combinations with protein fragment complementation JF - Protein engineering design & selection N2 - The twin-arginine translocation (TAT) pathway of the bacterial cytoplasmic membrane mediates translocation only of proteins that accomplished a native-like conformation. We deploy this feature in modular selection systems for directed evolution, in which folding helpers as well as dimeric or oligomeric proteinprotein interactions enable TAT-dependent translocation of the resistance marker TEM -lactamase (L). Specifically, we demonstrate and analyze selection of (i) enhancers for folding by direct TAT translocation selection of a target protein interposed between the TorA signal sequence and L, (ii) dimeric or oligomeric proteinprotein interactions by hitchhiker translocation (HiT) selection of proteins fused to the TorA signal sequence and to the L, respectively and (iii) heterotrimeric proteinprotein interactions by combining HiT with protein fragment complementation selection of proteins fused to two split L fragments and TorA, respectively. The lactamase fragments were additionally engineered for improved activity and stability. Applicability was benchmarked with interaction partners of known affinity and multimerization whereby cellular fitness correlated well with biophysical protein properties. Ultimately, the HiT selection was employed to identify peptides, which specifically bind to leukemia- and melanoma-relevant target proteins (MITF and ETO) by coiled-coil or tetra-helix-bundle formation with high affinity. The various versions of TAT selection led to inhibiting peptides (iPEPs) of disease-promoting interactions and enabled so far difficult to achieve selections. KW - HiT selection KW - NHR2 KW - TAT selection KW - three hybrid KW - two hybrid Y1 - 2013 U6 - https://doi.org/10.1093/protein/gzs098 SN - 1741-0126 VL - 26 IS - 3 SP - 225 EP - 242 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Hoffmann, H. A1 - Seiß, Martin A1 - Spahn, Frank T1 - Vertical relaxation of a moonlet propeller in Saturn's a ring JF - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters N2 - Two images, taken by the Cassini spacecraft near Saturn's equinox in 2009 August, show the Earhart propeller casting a 350 km long shadow, offering the opportunity to watch how the ring height, excited by the propeller moonlet, relaxes to an equilibrium state. From the shape of the shadow cast and a model of the azimuthal propeller height relaxation, we determine the exponential cooling constant of this process to be lambda = 0.07 +/- 0.02 km(-1), and thereby determine the collision frequency of the ring particles in the vertically excited region of the propeller to be omega(c)/Omega = 0.9 +/- 0.2. KW - planets and satellites: individual (Saturn) KW - planets and satellites: rings Y1 - 2013 U6 - https://doi.org/10.1088/2041-8205/765/1/L4 SN - 2041-8205 VL - 765 IS - 1 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Linklater, Wayne L. A1 - Mayer, Katharina A1 - Swaisgood, Ronald R. T1 - Chemical signals of age, sex and identity in black rhinoceros JF - Animal behaviour N2 - Olfactory communication may be particularly important to black rhinoceros, Diceros bicornis, because they are solitary living and have comparatively poor eyesight but their populations are structured by inter-and intrasexual relationships. Understanding olfactory functions and processes might achieve better conservation management but their study in rhinoceros remains anecdotal or descriptive. Experimental approaches are required but rarely possible as rhinoceros are difficult to observe and manipulate. We measured the olfactory investigation behaviour (duration and frequency of sniffing) of black rhinoceros in four experiments designed to determine the function of chemosignals in dung and urine. A habituationedishabituation trial demonstrated that black rhinoceros discriminated individually distinctive odours from faecal signals (experiment 1). When adults (>6 years old) were presented with dung from conspecifics of different sex and age classes (adult, and subadult from 2 to 4 years old), male dung was investigated more by both sexes, and females investigated subadult dung more (experiment 2). Both dung and urine from the same adult donors were investigated by both sexes, but male dung was investigated more than female dung and female urine more than male urine, although differences were statistically weak (experiment 3). Lastly, fresh faecal samples and those aged 1, 2, 4, 16 and 32 days were similarly investigated, indicating that they still function as olfactory signals. Together the results indicate that dung or urine signalled age, sex and identity to conspecifics and signals may persist as dung decays. Chemosignals are likely to be important to the social and spatial organization of black rhinoceros. KW - black rhinoceros KW - Diceros bicornis var. minor KW - dung KW - faeces KW - hook-lipped rhinoceros KW - individual discrimination KW - olfactory communication KW - signal KW - urine Y1 - 2013 U6 - https://doi.org/10.1016/j.anbehav.2012.12.034 SN - 0003-3472 VL - 85 IS - 3 SP - 671 EP - 677 PB - Elsevier CY - London ER - TY - JOUR A1 - Kliegl, Reinhold A1 - Hohenstein, Sven A1 - Yan, Ming A1 - McDonald, Scott A. T1 - How preview space/time translates into preview cost/benefit for fixation durations during reading JF - The quarterly journal of experimental psychology N2 - Eye-movement control during reading depends on foveal and parafoveal information. If the parafoveal preview of the next word is suppressed, reading is less efficient. A linear mixed model (LMM) reanalysis of McDonald (2006) confirmed his observation that preview benefit may be limited to parafoveal words that have been selected as the saccade target. Going beyond the original analyses, in the same LMM, we examined how the preview effect (i.e., the difference in single-fixation duration, SFD, between random-letter and identical preview) depends on the gaze duration on the pretarget word and on the amplitude of the saccade moving the eye onto the target word. There were two key results: (a) The shorter the saccade amplitude (i.e., the larger preview space), the shorter a subsequent SFD with an identical preview; this association was not observed with a random-letter preview. (b) However, the longer the gaze duration on the pretarget word, the longer the subsequent SFD on the target, with the difference between random-letter string and identical previews increasing with preview time. A third patternincreasing cost of a random-letter string in the parafovea associated with shorter saccade amplitudeswas observed for target gaze durations. Thus, LMMs revealed that preview effects, which are typically summarized under preview benefit, are a complex mixture of preview cost and preview benefit and vary with preview space and preview time. The consequence for reading is that parafoveal preview may not only facilitate, but also interfere with lexical access. KW - Eye movements KW - Reading KW - Preview effects KW - Linear mixed model KW - Boundary paradigm Y1 - 2013 U6 - https://doi.org/10.1080/17470218.2012.658073 SN - 1747-0218 SN - 1747-0226 VL - 66 IS - 3 SP - 581 EP - 600 PB - Wiley CY - Hove ER - TY - JOUR A1 - Wotschack, Christiane A1 - Kliegl, Reinhold T1 - Reading strategy modulates parafoveal-on-foveal effects in sentence reading JF - The quarterly journal of experimental psychology N2 - Task demands and individual differences have been linked reliably to word skipping during reading. Such differences in fixation probability may imply a selection effect for multivariate analyses of eye-movement corpora if selection effects correlate with word properties of skipped words. For example, with fewer fixations on short and highly frequent words the power to detect parafoveal-on-foveal effects is reduced. We demonstrate that increasing the fixation probability on function words with a manipulation of the expected difficulty and frequency of questions reduces an age difference in skipping probability (i.e., old adults become comparable to young adults) and helps to uncover significant parafoveal-on-foveal effects in this group of old adults. We discuss implications for the comparison of results of eye-movement research based on multivariate analysis of corpus data with those from display-contingent manipulations of target words. KW - Fixational selectivity KW - Parafoveal-on-foveal effects KW - Reading strategy KW - Distributed processing KW - Eye movements in reading Y1 - 2013 U6 - https://doi.org/10.1080/17470218.2011.625094 SN - 1747-0218 VL - 66 IS - 3 SP - 548 EP - 562 PB - Wiley CY - Hove ER - TY - JOUR A1 - Ghahghaei, Saeideh A1 - Linnell, Karina J. A1 - Fischer, Martin H. A1 - Dubey, Amit A1 - Davis, Robert T1 - Effects of load on the time course of attentional engagement, disengagement, and orienting in reading JF - The quarterly journal of experimental psychology N2 - We examined how the frequency of the fixated word influences the spatiotemporal distribution of covert attention during reading. Participants discriminated gaze-contingent probes that occurred with different spatial and temporal offsets from randomly chosen fixation points during reading. We found that attention was initially focused at fixation and that subsequent defocusing was slower when the fixated word was lower in frequency. Later in a fixation, attention oriented more towards the next saccadic target for high- than for low-frequency words. These results constitute the first report of the time course of the effect of load on attentional engagement and orienting in reading. They are discussed in the context of serial and parallel models of reading. KW - Attention KW - Load KW - Reading KW - Time course KW - Word frequency KW - Engagement KW - Disengagement KW - Orienting Y1 - 2013 U6 - https://doi.org/10.1080/17470218.2011.635795 SN - 1747-0218 VL - 66 IS - 3 SP - 453 EP - 470 PB - Wiley CY - Hove ER - TY - JOUR A1 - Mühlbauer, Thomas A1 - Gollhofer, Albert A1 - Granacher, Urs T1 - Association of balance, strength, and power measures in young adults JF - Journal of strength and conditioning research : the research journal of the NSCA N2 - Muehlbauer, T, Gollhofer, A, and Granacher, U. Association of balance, strength, and power measures in young adults. J Strength Cond Res 27(3): 582-589, 2013-The purpose of this study was to investigate the relationship between variables of static/dynamic balance, isometric strength, and power. Twenty-seven young healthy adults (mean age: 23 6 4 years) performed measurements of static (unperturbed)/dynamic (perturbed) balance, isometric strength (i.e., maximal isometric torque [MIT]; rate of torque development [RTD] of the plantar flexor), and power (i.e., countermovement jump [CMJ] height and power). No significant associations were found between variables of static and dynamic balance (r = -0.090 to + 0.329, p > 0.05) and between measures of static/dynamic balance and isometric strength (r = +0.041 to +0.387, p > 0.05) and static/dynamic balance and power (r = -0.076 to + 0.218, p > 0.05). Significant positive correlations (r) were detected between variables of power and isometric strength ranging from +0.458 to +0.689 (p, 0.05). Furthermore, simple regression analyses revealed that a 10% increase in mean CMJ height (4.1 cm) was associated with 22.9 N.m and 128.4 N.m.s(-1) better MIT and RTD, respectively. The nonsignificant correlation between static and dynamic balance measures and between static/dynamic balance, isometric strength, and power variables implies that these capacities may be independent of each other and may have to be tested and trained complementarily. KW - static/dynamic postural control KW - maximal isometric torque KW - rate of torque development KW - jump height/power Y1 - 2013 U6 - https://doi.org/10.1097/JSC.0b013e31825c2bab SN - 1064-8011 VL - 27 IS - 3 SP - 582 EP - 589 PB - Lippincott Williams & Wilkins CY - Philadelphia ER - TY - JOUR A1 - Richter, Dania A1 - Schröder-Esselbach, Boris A1 - Hartmann, Niklas K. A1 - Matuschka, Franz-Rainer T1 - Spatial stratification of various Lyme disease spirochetes in a Central European site JF - FEMS microbiology ecology N2 - To determine whether the genospecies composition of Lyme disease spirochetes is spatially stratified, we collected questing Ixodes ricinus ticks in neighboring plots where rodents, birds, and lizards were present as reservoir host and compared the prevalence of various genospecies. The overall prevalence of spirochetes in questing ticks varied across the study site. Borrelia lusitaniae appeared to infect adult ticks in one plot at the same frequency as did Borrelia afzelii in the other plots. The relative density of questing nymphal and adult ticks varied profoundly. Where lizards were exceedingly abundant, these vertebrates seemed to constitute the dominant host for nymphal ticks, contributing the majority of infected adult ticks. Because lizards support solely B.lusitaniae and appear to exclude other genospecies, their narrow genospecies association results in predominance of B.lusitaniae in sites where lizards are abundant, while limiting its spread to the host's habitat range. To the extent that Central European B.lusitaniae strains are nonpathogenic, the presence of numerous lizards should locally decrease risk of infection for people. Evaluation of regional risk of infection by Lyme disease spirochetes should take the spatial effect of hosts into consideration, which stratify the distribution of specifically infected ticks on a small scale. KW - Lyme disease KW - Borrelia lusitaniae KW - Borrelia afzelii KW - stratification KW - lizard KW - zooprophylaxis Y1 - 2013 U6 - https://doi.org/10.1111/1574-6941.12029 SN - 0168-6496 VL - 83 IS - 3 SP - 738 EP - 744 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Eigemann, Falk A1 - Hilt, Sabine A1 - Salka, Ivette A1 - Grossart, Hans-Peter T1 - Bacterial community composition associated with freshwater algae species specificity vs. dependency on environmental conditions and source community JF - FEMS microbiology ecology N2 - We studied bacterial associations with the green alga Desmodesmus armatus and the diatom Stephanodiscus minutulus under changing environmental conditions and bacterial source communities, to evaluate whether bacteriaalgae associations are species-specific or more generalized and determined by external factors. Axenic and xenic algae were incubated in situ with and without allelopathically active macrophytes, and in the laboratory with sterile and nonsterile lake water and an allelochemical, tannic acid (TA). Bacterial community composition (BCC) of algae-associated bacteria was analyzed by denaturing gradient gel electrophoresis (DGGE), nonmetric multidimensional scaling, cluster analyses, and sequencing of DGGE bands. BCC of xenic algal cultures of both species were not significantly affected by changes in their environment or bacterial source community, except in the case of TA additions. Species-specific interactions therefore appear to overrule the effects of environmental conditions and source communities. The BCC of xenic and axenic D.armatus cultures subjected to in situ bacterial colonization, however, had lower similarities (ca.55%), indicating that bacterial precolonization is a strong factor for bacteriaalgae associations irrespective of environmental conditions and source community. Our findings emphasize the ecological importance of species-specific bacteriaalgae associations with important repercussions for other processes, such as the remineralization of nutrients, and organic matter dynamics. KW - allelopathy KW - bacteriaalgae associations KW - heterotrophic bacteria KW - species-specific Y1 - 2013 U6 - https://doi.org/10.1111/1574-6941.12022 SN - 0168-6496 VL - 83 IS - 3 SP - 650 EP - 663 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Espe, Katharina M. A1 - Raila, Jens A1 - Henze, Andrea A1 - Blouin, Katja A1 - Schneider, Andreas A1 - Schmiedeke, Daniel A1 - Krane, Vera A1 - Pilz, Stefan A1 - Schweigert, Florian J. A1 - Hocher, Berthold A1 - Wanner, Christoph A1 - Drechsler, Christiane T1 - Low plasma alpha-tocopherol concentrations and adverse clinical outcomes in diabetic hemodialysis patients JF - Clinical journal of the American Society of Nephrology N2 - Background and objectives Trials with the antioxidant vitamin E have failed to show benefit in the general population. Considering the different causes of death in ESRD, this study investigated the association between plasma concentrations of alpha-tocopherol and specific clinical outcomes in diabetic hemodialysis patients. Design, settings, participants, & measurements In 1046 diabetic hemodialysis patients (participants of the German Diabetes and Dialysis Study), alpha-tocopherol was measured in plasma by reversed-phase HPLC. By Cox regression analyses, hazard ratios were determined for prespecified end points according to baseline plasma alpha-tocopherol levels: sudden death (n=134), myocardial infarction (n=172), stroke (n=89), combined cardiovascular events (n=398), fatal infection (n=107), and all-cause mortality (n=508). Results Patients had a mean age of 66 8 years, and mean plasma alpha-tocopherol level was 22.8+/-9.6 mu mol/L. Levels of alpha-tocopherol were highly correlated to triglycerides (r=0.63, P<0.001). Patients in the lowest alpha-tocopherol quartile had (in unadjusted analyses) a 79% higher risk of stroke and a 31% higher risk of all-cause mortality compared with patients in the highest quartile. The associations were attenuated after adjustment for confounders (hazard ratio(stroke)=1.56, 95% confidence interval=0.75-3.25; hazard ratio(mortality)=1.22, 95% confidence interval=0.89-1.69, respectively). There was no association between alpha-tocopherol and myocardial infarction, sudden death, or infectious death. Conclusions Plasma alpha-tocopherol concentrations were not independently associated with cardiovascular outcomes, infectious deaths, or all-cause mortality in diabetic hemodialysis patients. The lack of association can partly be explained by a confounding influence of malnutrition, which should be considered in the planning of trials to reduce cardiovascular risk in dialysis patients. Y1 - 2013 U6 - https://doi.org/10.2215/CJN.04880511 SN - 1555-9041 VL - 8 IS - 3 SP - 452 EP - 458 PB - American Society of Nephrology CY - Washington ER - TY - JOUR A1 - Hass, Roland A1 - Münzberg, Marvin A1 - Bressel, Lena A1 - Reich, Oliver T1 - Industrial applications of photon density wave spectroscopy for in-line particle sizing [Invited] JF - Applied optics N2 - Optical spectroscopy in highly turbid liquid material is often restricted by simultaneous occurrence of absorption and scattering of light. Photon Density Wave (PDW) spectroscopy is one of the very few, yet widely unknown, technologies for the independent quantification of these two optical processes. Here, a concise overview about modern PDW spectroscopy is given, including all necessary equations concerning the optical description of the investigated material, dependent light scattering, particle sizing, and PDW spectroscopy itself. Additionally, it is shown how the ambiguity in particle sizing, arising from Mie theory, can be correctly solved. Due to its high temporal resolution, its applicability to highest particle concentrations, and its purely fiber-optical probe, PDW spectroscopy possesses all fundamental characteristics for optical in-line process analysis. Several application examples from the chemical industry are presented. (C) 2013 Optical Society of America Y1 - 2013 U6 - https://doi.org/10.1364/AO.52.001423 SN - 1559-128X SN - 2155-3165 VL - 52 IS - 7 SP - 1423 EP - 1431 PB - Optical Society of America CY - Washington ER - TY - JOUR A1 - Hinzen, Klaus-G A1 - Reamer, Sharon K. A1 - Scherbaum, Frank T1 - Slow fourier transform JF - Seismological research letters Y1 - 2013 U6 - https://doi.org/10.1785/0220120139 SN - 0895-0695 VL - 84 IS - 2 SP - 251 EP - 257 PB - Seismological Society of America CY - Albany ER - TY - JOUR A1 - van de Vijver, Ruben A1 - Baer-Henney, Dinah T1 - On the role of phonetic motivation and frequency in the acquisition of alternations JF - Zeitschrift für Literaturwissenschaft und Linguistik N2 - On the Role of Phonetic Motivation and Frequency in the Acquisition of Alternations German nouns may alternate in two ways: a final word-final voiceless obstruent in the singular may correspond to a voiced one in the plural and a back vowel in the singular may correspond to a front one in the plural. We investigate the role of phonetic motivation and frequency in the acquisition of these alternations. The voicing alternation has a phonetic motivation, but the vowel alternation does not. On the basis of two corpus studies, we conclude that both alternations occur with equal frequency in the ambient language. In two production experiments, one with 5-year-olds and one with adults, we asked both populations to form plurals for given singular words and nonces. The children produce more voicing alternations in nonces than adults and fewer vowel alternations than adults. We conclude that children rely more on phonetic motivation than adults. Y1 - 2013 SN - 0049-8653 VL - 43 IS - 169 SP - 49 EP - 64 PB - Universitätsverlag Potsdam CY - Stuttgart ER - TY - JOUR A1 - Zimmermann, Alexander A1 - Schinn, Dustin S. A1 - Francke, Till A1 - Elsenbeer, Helmut A1 - Zimmermann, Beate T1 - Uncovering patterns of near-surface saturated hydraulic conductivity in an overland flow-controlled landscape JF - Geoderma : an international journal of soil science N2 - Saturated hydraulic conductivity (K-s) is an important soil characteristic affecting soil water storage, runoff generation and erosion processes. In some areas where high-intensity rainfall coincides with low K-s values at shallow soil depths, frequent overland flow entails dense drainage networks. Consequently, linear structures such as flowlines alternate with inter-flowline areas. So far, investigations of the spatial variability of K-s mainly relied on isotropic covariance models which are unsuitable to reveal patterns resulting from linear structures. In the present study, we applied two sampling approaches so as to adequately characterize K-s spatial variability in a tropical forest catchment that features a high density of flowlines: A classical nested sampling survey and a purposive sampling strategy adapted to the presence of flowlines. The nested sampling approach revealed the dominance of small-scale variability, which is in line with previous findings. Our purposive sampling, however, detected a strong spatial gradient: surface K-s increased substantially as a function of distance to flowline; 10 m off flowlines, values were similar to the spatial mean of K-s. This deterministic trend can be included as a fixed effect in a linear mixed modeling framework to obtain realistic spatial fields of K-s. In a next step we used probability maps based on those fields and prevailing rainfall intensities to assess the hydrological relevance of the detected pattern. This approach suggests a particularly good agreement between the probability statements of K-s exceedance and observed overland flow occurrence during wet stages of the rainy season. KW - Soil hydrology KW - Saturated hydraulic conductivity KW - Overland flow generation KW - Spatial patterns KW - Drainage network Y1 - 2013 U6 - https://doi.org/10.1016/j.geoderma.2012.11.002 SN - 0016-7061 VL - 195 IS - 169 SP - 1 EP - 11 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Buchmann, Carsten M. A1 - Schurr, Frank Martin A1 - Nathan, Ran A1 - Jeltsch, Florian T1 - Habitat loss and fragmentation affecting mammal and bird communities-The role of interspecific competition and individual space use JF - Ecological informatics : an international journal on ecoinformatics and computational ecolog N2 - Fragmentation and loss of habitat are major threats to animal communities and are therefore important to conservation. Due to the complexity of the interplay of spatial effects and community processes, our mechanistic understanding of how communities respond to such landscape changes is still poor. Modelling studies have mostly focused on elucidating the principles of community response to fragmentation and habitat loss at relatively large spatial and temporal scales relevant to metacommunity dynamics. Yet, it has been shown that also small scale processes, like foraging behaviour, space use by individuals and local resource competition are also important factors. However, most studies that consider these smaller scales are designed for single species and are characterized by high model complexity. Hence, they are not easily applicable to ecological communities of interacting individuals. To fill this gap, we apply an allometric model of individual home range formation to investigate the effects of habitat loss and fragmentation on mammal and bird communities, and, in this context, to investigate the role of interspecific competition and individual space use. Results show a similar response of both taxa to habitat loss. Community composition is shifted towards higher frequency of relatively small animals. The exponent and the 95%-quantile of the individual size distribution (ISD, described as a power law distribution) of the emerging communities show threshold behaviour with decreasing habitat area. Fragmentation per se has a similar and strong effect on mammals, but not on birds. The ISDs of bird communities were insensitive to fragmentation at the small scales considered here. These patterns can be explained by competitive release taking place in interacting animal communities, with the exception of bird's buffering response to fragmentation, presumably by adjusting the size of their home ranges. These results reflect consequences of higher mobility of birds compared to mammals of the same size and the importance of considering competitive interaction, particularly for mammal communities, in response to landscape fragmentation. Our allometric approach enables scaling up from individual physiology and foraging behaviour to terrestrial communities, and disentangling the role of individual space use and interspecific competition in controlling the response of mammal and bird communities to landscape changes. KW - Allometry KW - Body size KW - Fractal landscapes KW - Foraging movement KW - Individual-based model KW - Locomotion costs Y1 - 2013 U6 - https://doi.org/10.1016/j.ecoinf.2012.11.015 SN - 1574-9541 VL - 14 SP - 90 EP - 98 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kiertscher, Simon A1 - Zinke, Jörg A1 - Schnor, Bettina T1 - CHERUB power consumption aware cluster resource management JF - Cluster computing : the journal of networks, software tools and applications N2 - This paper presents an evaluation of ACPI energy saving modes, and deduces the design and implementation of an energy saving daemon for clusters called cherub. The design of the cherub daemon is modular and extensible. Since the only requirement is a central approach for resource management, cherub is suited for Server Load Balancing (SLB) clusters managed by dispatchers like Linux Virtual Server (LVS), as well as for High Performance Computing (HPC) clusters. Our experimental results show that cherub's scheduling algorithm works well, i.e. it will save energy, if possible, and avoids state-flapping. KW - Green computing KW - Cluster computing Y1 - 2013 U6 - https://doi.org/10.1007/s10586-011-0176-5 SN - 1386-7857 VL - 16 IS - 1 SP - 55 EP - 63 PB - Springer CY - New York ER - TY - JOUR A1 - Lange, J. A1 - Pohl, Martin T1 - The average GeV-band emission from gamma-ray bursts JF - Astronomy and astrophysics : an international weekly journal N2 - Aims. We analyze the emission in the 0.3-30 GeV energy range of gamma-ray bursts detected with the Fermi Gamma-ray Space Telescope. We concentrate on bursts that were previously only detected with the Gamma-Ray Burst Monitor in the keV energy range. These bursts will then be compared to the bursts that were individually detected with the Large Area Telescope at higher energies. Methods. To estimate the emission of faint GRBs we used nonstandard analysis methods and sum over many GRBs to find an average signal that is significantly above background level. We used a subsample of 99 GRBs listed in the Burst Catalog from the first two years of observation. Results. Although most are not individually detectable, the bursts not detected by the Large Area Telescope on average emit a significant flux in the energy range from 0.3 GeV to 30 GeV, but their cumulative energy fluence is only 8% of that of all GRBs. Likewise, the GeV-to-MeV flux ratio is less and the GeV-band spectra are softer. We confirm that the GeV-band emission lasts much longer than the emission found in the keV energy range. The average allsky energy flux from GRBs in the GeV band is 6.4 x 10(-4) erg cm(-2) yr(-1) or only similar to 4% of the energy flux of cosmic rays above the ankle at 10(18.6) eV. KW - methods: statistical KW - surveys KW - gamma-ray burst: general Y1 - 2013 U6 - https://doi.org/10.1051/0004-6361/201220652 SN - 0004-6361 VL - 551 IS - 1 PB - EDP Sciences CY - Les Ulis ER -