BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models

Background: Quantitative models of biochemical and cellular systems are used to answer a variety of questions in the biological sciences. The number of published quantitative models is growing steadily thanks to increasing interest in the use of models as well as the development of improved software systems and the availability of better, cheaper computer hardware. To maximise the benefits of this growing body of models, the field needs centralised model repositories that will encourage, facilitate and promote model dissemination and reuse. Ideally, the models stored in these repositories should be extensively tested and encoded in community-supported and standardised formats. In addition, the models and their components should be cross-referenced with other resources in order to allow their unambiguous identification. Description: BioModels Database http://www.ebi.ac.uk/biomodels/ is aimed at addressing exactly these needs. It is a freely-accessible online resource for storing, viewing, retrieving, and analysing published, peer-reviewed quantitative models of biochemical and cellular systems. The structure and behaviour of each simulation model distributed by BioModels Database are thoroughly checked; in addition, model elements are annotated with terms from controlled vocabularies as well as linked to relevant data resources. Models can be examined online or downloaded in various formats. Reaction network diagrams generated from the models are also available in several formats. BioModels Database also provides features such as online simulation and the extraction of components from large scale models into smaller submodels. Finally, the system provides a range of web services that external software systems can use to access up-to-date data from the database. Conclusions: BioModels Database has become a recognised reference resource for systems biology. It is being used by the community in a variety of ways; for example, it is used to benchmark different simulation systems, and to study the clustering of models based upon their annotations. Model deposition to the database today is advised by several publishers of scientific journals. The models in BioModels Database are freely distributed and reusable; the underlying software infrastructure is also available from SourceForge https://sourceforge.net/projects/biomodels/ under the GNU General Public License

Speciation Along Environmental Gradients

Traditional discussions of speciation are based on geographical patterns of species ranges. In allopatric speciation, long-term geographical isolation generates reproductively isolated and spatially segregated descendant species. In the absence of geographical barriers, diversification is hindered by gene flow. Yet a growing body of phylogenetic and experimental data suggests that closely related species often occur in sympatry or have adjacent ranges in regions over which environmental changes are gradual and do not prevent gene flow. Theory has identified a variety of evolutionary processes that can result in speciation under sympatric conditions, with some recent advances concentrating on the phenomenon of evolutionary branching. Here we establish a link between geographical patterns and ecological processes of speciation by studying evolutionary branching in spatially structured populations. We show that along an environmental gradient, evolutionary branching can occur much more easily than in non-spatial models. This facilitation is most pronounced for gradients of intermediate slope. Moreover, spatial evolutionary branching readily generates patterns of spatial segregation and abutment between the emerging species. Our results highlight the importance of local processes of adaptive divergence for geographical patterns of speciation, and caution against pitfalls of inferring past speciation processes from present biogeographical patterns

Studium, Berufswahl und Berufstätigkeit: Nürnberger Sozialwirte zwischen 1981 und 1994

In dem Beitrag wird der berufliche Verbleib der Nürnberger Sozialwirte anhand einer Befragung der Absolventen von 1991 bis 1994 untersucht. Studiumsgestaltung, Berufssuche und Bewerbungsverhalten sowie Aspekte der ausgeübten Berufstätigkeit und Studiengangsevaluation werden erfaßt. Es wird festgestellt, daß die Übergangsphase zwischen Studiumsende und Aufnahme eines Berufs durch verschiedene kulturelle, institutionale, situationale und personale Faktoren beeinflußt ist. Mehr als die Hälfte der Befragten konnte trotz der Probleme auf dem Stellenmarkt für Akademiker ihre Arbeitsmarktchancen nutzen und geht einer geregelten Tätigkeit nach. Zufriedenheit wird sowohl hinsichtlich des Studiums als auch hinsichtlich der Beschäftigungssituation festgestellt. Insgesamt deutet die Studie auf die Vorteile der Kombination mit wirtschaftswissenschaftlichen Inhalten hin und unterstreicht die positive Wirkung von Berufspraktika für die Berufseinmündung. (ICA

The genomic basis of adaptive evolution in threespine sticklebacks

Marine stickleback fish have colonized and adapted to thousands of streams and lakes formed since the last ice age, providing an exceptional opportunity to characterize genomic mechanisms underlying repeated ecological adaptation in nature. Here we develop a high-quality reference genome assembly for threespine sticklebacks. By sequencing the genomes of twenty additional individuals from a global set of marine and freshwater populations, we identify a genome-wide set of loci that are consistently associated with marine–freshwater divergence. Our results indicate that reuse of globally shared standing genetic variation, including chromosomal inversions, has an important role in repeated evolution of distinct marine and freshwater sticklebacks, and in the maintenance of divergent ecotypes during early stages of reproductive isolation. Both coding and regulatory changes occur in the set of loci underlying marine–freshwater evolution, but regulatory changes appear to predominate in this well known example of repeated adaptive evolution in nature.National Human Genome Research Institute (U.S.)National Human Genome Research Institute (U.S.) (NHGRI CEGS Grant P50-HG002568

Treatment of Highland Frogs from the Two- Legged Stage with Homeopathically Prepared Thyroxin (10 -11 -10 -21 )

The influence of moderately diluted, agitated, i.e., homeopathically prepared, thyroxin solutions (10 -11 -10 -21 , final concentration in the basin water 0.6 × 10 -15 -0.6 × 10 -25 parts by weight after the first application) on metamorphosis in highland Rana temporaria from the two-legged stage was studied. In accordance with the homeopathic idea of effects of specially prepared dilutions being inverse to those of their mother substances, animals were treated either with thyroxin 10 -11 -10 -21 or analogously prepared blank solution (water). Development was monitored by documenting the number of animals that had entered the four-legged stage. It has been found that animals treated with the thyroxin solutions metamorphosed more slowly than the control animals, i.e., the effect of the homeopathically prepared thyroxin was opposed to the usual effect of molecular thyroxin. The number of test animals that reached the four-legged stage at defined points in time was smaller (2-13.5%) in the group treated with homeopathically prepared thyroxin at the points in time, compared to control. The results in this study sustain the previous multiresearcher findings that show that diluted homeopathically prepared thyroxin is able to slow down metamorphosis of R. temporaria

Little evidence for a selective advantage of armour-reduced threespined stickleback individuals in an invertebrate predation experiment

The repeated colonization of freshwater habitats by the ancestrally marine threespined stickleback Gasterosteus aculeatus has been associated with many instances of parallel reduction in armour traits, most notably number of lateral plates. The change in predation regime from marine systems, dominated by gape-limited predators such as piscivorous fishes, to freshwater habitats where grappling invertebrate predators such as insect larvae can dominate the predation regime, has been hypothesized as a driving force. Here we experimentally test the hypothesis that stickleback with reduced armour possess a selective advantage in the face of predation by invertebrates, using a natural population of stickleback that is highly polymorphic for armour traits and a common invertebrate predator from the same location. Our results provide no compelling evidence for selection in this particular predator–prey interaction. We suggest that the postulated selective advantage of low armour in the face of invertebrate predation may not be universal

Supplementary material from "Why are biting flies attracted to blue objects?"

Diurnal biting flies are strongly attracted to blue objects. This behaviour is widely exploited for fly control, but its functional significance is debated. It is hypothesized that blue objects resemble animal hosts; blue surfaces resemble shaded resting places and blue attraction is a by-product of attraction to polarized light. We computed the fly photoreceptor signals elicited by a large sample of leaf and animal integument reflectance spectra, viewed under open/cloudy illumination and under woodland shade. We then trained artificial neural networks (ANNs) to distinguish animals from leaf backgrounds, and shaded from unshaded surfaces, in order to find the optimal means of doing so based upon the sensory information available to a fly. After training, we challenged ANNs to classify blue objects used in fly control. Trained ANNs could make both discriminations with high accuracy. They discriminated animals from leaves based upon blue-green photoreceptor opponency and commonly misclassified blue objects as animals. Meanwhile, they discriminated shaded from unshaded stimuli using achromatic cues and never misclassified blue objects as shaded. We conclude that blue-green opponency is the most effective means of discriminating animals from leaf backgrounds using a fly's sensory information, and that blue objects resemble animal hosts through such mechanisms

Coarse‐Grained Refractory Composite Castables Based on Alumina and Niobium

Niobium-alumina composite aggregates with 60 vol% metal content and with particle sizes up to 3150 μm are produced using castable technology followed by sintering, and a crushing and sieving process. X-Ray diffraction (XRD) analysis reveals phase separation during crushing as the niobium:corundum volume ratios is between 37:57 and 64:31 among the 4 produced aggregate classes 0–45, 45–500, 500–1000, and 1000–3150 μm. The synthesized aggregates are used to produce coarse-grained refractory composites in a second casting and sintering step. The fine- and coarse-grained material shows porosities between 32% and 36% with a determined cold modulus of rupture of 20 and 12 MPa, and E-moduli of 37 and 46 GPa, respectively. The synthesized fine-grained composites reached true strain values between 0.08 at 1100 °C and 0.18 at 1500 °C and the coarse-grained ones values between 0.02 and 0.09. The electrical conductivity for the fine-grained and the coarse-grained material is 448±66 and 111±25  S cm$^{−1}$, respectively