Collective Animal Behavior from Bayesian Estimation and Probability Matching

Animals living in groups make movement decisions that depend, among other factors, on social interactions with other group members. Our present understanding of social rules in animal collectives is based on empirical fits to observations and we lack first-principles approaches that allow their derivation. Here we show that patterns of collective decisions can be derived from the basic ability of animals to make probabilistic estimations in the presence of uncertainty. We build a decision-making model with two stages: Bayesian estimation and probabilistic matching.
In the first stage, each animal makes a Bayesian estimation of which behavior is best to perform taking into account personal information about the environment and social information collected by observing the behaviors of other animals. In the probability matching stage, each animal chooses a behavior with a probability given by the Bayesian estimation that this behavior is the most appropriate one. This model derives very simple rules of interaction in animal collectives that depend only on two types of reliability parameters, one that each animal assigns to the other animals and another given by the quality of the non-social information. We test our model by obtaining theoretically a rich set of observed collective patterns of decisions in three-spined sticklebacks, Gasterosteus aculeatus, a shoaling fish species. The quantitative link shown between probabilistic estimation and collective rules of behavior allows a better contact with other fields such as foraging, mate selection, neurobiology and psychology, and gives predictions for experiments directly testing the relationship between estimation and collective behavior

Microdevices for extensional rheometry of low viscosity elastic liquids : a review

Extensional flows and the underlying stability/instability mechanisms are of extreme relevance to the efficient operation of inkjet printing, coating processes and drug delivery systems, as well as for the generation of micro droplets. The development of an extensional rheometer to characterize the extensional properties of low viscosity fluids has therefore stimulated great interest of researchers, particularly in the last decade. Microfluidics has proven to be an extraordinary working platform and different configurations of potential extensional microrheometers have been proposed. In this review, we present an overview of several successful designs, together with a critical assessment of their capabilities and limitations

Templat-basierte Parallelsynthese von Carbonsäureamidbibliotheken; Cyclopentanolamine als chirale Plattform für molekulare Diversität

Die schnelle Bereitstellung einer großen Anzahl an Strukturvariationen eines Leitmotivs ist eine der Schlüsselaufgaben der medizinischen Chemie. Auf diesem Gebiet hat sich in den letzten Jahren mehr und mehr der Einsatz polymergebundener Reagenzien bewährt. Vorteile dieser Vorgehensweise liegen in der schnellen und vergleichsweise kostengünstigen Bereitstellung der gewünschten Substanzbibliotheken und in der Möglichkeit, durch forcierte Reaktionsbedingungen mittels hoher Reagenzienüberschüsse quantitative Umsetzungen „erzwingen“ zu können. Auf diese Weise können zuvor aufwändig hergestellte und damit wertvollere Intermediate besonders effektiv zu den gewünschten Endprodukten umgesetzt werden. Darüber hinaus erlauben entsprechende Syntheseoperationen eine in der Regel unkomplizierte Verfolgung der Reaktionsverläufe mit einfacher anschließender Isolierung der Produkte durch Filtration. Auf Grund der hohen Umsetzungsraten können die erstrebten Testverbindungen in vergleichsweise hohen Ausbeuten und Reinheiten erhalten werden, so dass langwierige und kostenintensive Aufreinigungsprozeduren, um das erforderliche Maß an Reproduzierbarkeit der anschließenden biologischen Untersuchungen zu gewährleisten, auf ein Minimum reduziert werden können. Im Fokus dieser Arbeit stand insbesondere die polymergestützte Parallelsynthese von leitstrukturartigen Carbonsäureamidbibliotheken. Zur Darstellung der gewünschten Substanzkollektive wurde ein konvergentes Syntheseregime (convergent Polymer Assisted Solution Phase synthesis; cPASP) verfolgt, wobei zunächst die benötigten Amino-Template durch konventionelle Synthese in Lösung zur Verfügung gestellt wurden. Parallel dazu konnten die erwünschten polymergebundenen Acylierungsreagenzien durch eine Kupplung der einzelnen Carbonsäuren an entsprechend funktionalisierte polymere Träger vorbereitet werden, wobei optional einzelne Acylfragmente weiterführend an der Festphase modifiziert wurden. Zur temporären Verankerung der Acylkomponenten kamen dabei der Kupplungs- und Freisetzungsanker (Couple&release-Linker) 4-Hydroxy-2,3,5,6-tetrafluorbenzoesäure bzw. der nach Ellman modifizierte Sicherungsanker (Kenner Safety-catch Linker) zum Einsatz. Abschließend erfolgte durch die Zusammenführung beider Synthesestränge der Transfer der Acylreste auf die entsprechenden Amino-Template, wobei die erwünschten Carbonsäureamide in Lösung anfielen und nach Filtration isoliert erhalten werden konnten. Grundsätzlich ist beim Einsatz Templat-basierter parallelsynthetischer Methoden allerdings die in der Regel stetige Zunahme des Molekülgewichts ein Hemmnis. Häufig werden dadurch letztendlich Moleküle mit vergleichsweise ungünstigen pharmakokinetischen Eigenschaften, wie zum Beispiel einer hohen Lipophilie, erhalten, deren Molekülparameter in weiteren Optimierungszyklen problematisch zu variieren sind. So standen in der vorliegenden Arbeit insbesondere kleine und damit durch eine niedrige relative Molmasse ausgezeichnete Amino-Template im Mittelpunkt, die auf Grund mehrerer funktioneller Gruppen vielfach substituierbar bzw. diversifizierbar waren. Als Grundgerüst wurde vorwiegend von einem an drei Positionen funktionalisierten Cyclopentanring ausgegangen, wobei der gewählte Syntheseweg die selektive Variation jeder einzelnen funktionalisierten Position erlaubte. Die Synthese der 1 (Amino)-2,4-dihydroxycyclopentan-Template erfolgte in neun Schritten. Dabei weisen die einzelnen Amino-Template jeweils drei im Laufe der Synthese entstehende Stereozentren auf. Die entsprechenden Racemate wurden anschließend nach einer Trennung der Diastereomerengemische erhalten. Des Weiteren wurden andere, leitstrukturorientierte Amino-Template synthetisiert und mit Acylresten dekoriert. Um dabei eine möglichst breit gestreute strukturelle Vielfalt zu erhalten, wurde diese so gewählt, dass sich durch parallelsynthetische Schritte Substituenten anfügen ließen, ohne dabei überladene, und damit aus physiologischer Sicht ungünstige Testverbindungen zu erhalten. Insgesamt wurden mit Hilfe des dargestellten Synthesekonzepts siebzehn neuartige Amino-Template jeweils zu den gewünschten Carbonsäureamidbibliotheken umgesetzt, die anschließend von verschiedenen Kooperationspartnern auf ihre biologischen Eigenschaften hin untersucht wurden

Physics of Neutron Star Crusts

The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.Comment: 182 pages, published version available at <http://www.livingreviews.org/lrr-2008-10

A supramolecular helix that disregards chirality

The functions of complex crystalline systems derived from supramolecular biological and non-biological assemblies typically emerge from homochiral programmed primary structures via first principles involving secondary, tertiary and quaternary structures. In contrast, heterochiral and racemic compounds yield disordered crystals, amorphous solids or liquids. Here, we report the self-assembly of perylene bisimide derivatives in a supramolecular helix that in turn self-organizes in columnar hexagonal crystalline domains regardless of the enantiomeric purity of the perylene bisimide. We show that both homochiral and racemic perylene bisimide compounds, including a mixture of 21 diastereomers that cannot be deracemized at the molecular level, self-organize to form single-handed helical assemblies with identical single-crystal-like order. We propose that this high crystalline order is generated via a cogwheel mechanism that disregards the chirality of the self-assembling building blocks. We anticipate that this mechanism will facilitate access to previously inaccessible complex crystalline systems from racemic and homochiral building blocks

Neutrinos from Stored Muons nuSTORM: Expression of Interest

The nuSTORM facility has been designed to deliver beams of electron and muon neutrinos from the decay of a stored muon beam with a central momentum of 3.8 GeV/c and a momentum spread of 10%. The facility is unique in that it will: serve the future long- and short-baseline neutrino-oscillation programmes by providing definitive measurements of electron-neutrino- and muon-neutrino-nucleus cross sections with percent-level precision; allow searches for sterile neutrinos of exquisite sensitivity to be carried out; and constitute the essential first step in the incremental development of muon accelerators as a powerful new technique for particle physics. Of the world's proton-accelerator laboratories, only CERN and FNAL have the infrastructure required to mount nuSTORM. Since no siting decision has yet been taken, the purpose of this Expression of Interest (EoI) is to request the resources required to: investigate in detail how nuSTORM could be implemented at CERN; and develop options for decisive European contributions to the nuSTORM facility and experimental programme wherever the facility is sited. The EoI defines a two-year programme culminating in the delivery of a Technical Design Report

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

The influence of organizational culture and climate on entrepreneurial intentions among research scientists

Over the past decades, universities have increasingly become involved in entrepreneurial activities. Despite efforts to embrace their ‘third mission’, universities still demonstrate great heterogeneity in terms of their involvement in academic entrepreneurship. This papers adopts an institutional perspective to understand how organizational characteristics affect research scientists’ entrepreneurial intentions. Specifically, we study the impact of university culture and climate on entrepreneurial intentions, including intentions to spin off a company, to engage in patenting or licensing and to interact with industry through contract research or consulting. Using a sample of 437 research scientists from Swedish and German universities, our results reveal that the extent to which universities articulate entrepreneurship as a fundamental element of their mission fosters research scientists’ intentions to engage in spin-off creation and intellectual property rights, but not industry-science interaction. Furthermore, the presence of university role models positively affects research scientists’ propensity to engage in entrepreneurial activities, both directly and indirectly through entrepreneurial self-efficacy. Finally, research scientists working at universities which explicitly reward people for ‘third mission’ related output show higher levels of spin-off and patenting or licensing intentions. This study has implications for both academics and practitioners, including university managers and policy makers

A "Candidate-Interactome" Aggregate Analysis of Genome-Wide Association Data in Multiple Sclerosis

Though difficult, the study of gene-environment interactions in multifactorial diseases is crucial for interpreting the relevance of non-heritable factors and prevents from overlooking genetic associations with small but measurable effects. We propose a “candidate interactome” (i.e. a group of genes whose products are known to physically interact with environmental factors that may be relevant for disease pathogenesis) analysis of genome-wide association data in multiple sclerosis. We looked for statistical enrichment of associations among interactomes that, at the current state of knowledge, may be representative of gene-environment interactions of potential, uncertain or unlikely relevance for multiple sclerosis pathogenesis: Epstein-Barr virus, human immunodeficiency virus, hepatitis B virus, hepatitis C virus, cytomegalovirus, HHV8-Kaposi sarcoma, H1N1-influenza, JC virus, human innate immunity interactome for type I interferon, autoimmune regulator, vitamin D receptor, aryl hydrocarbon receptor and a panel of proteins targeted by 70 innate immune-modulating viral open reading frames from 30 viral species. Interactomes were either obtained from the literature or were manually curated. The P values of all single nucleotide polymorphism mapping to a given interactome were obtained from the last genome-wide association study of the International Multiple Sclerosis Genetics Consortium & the Wellcome Trust Case Control Consortium, 2. The interaction between genotype and Epstein Barr virus emerges as relevant for multiple sclerosis etiology. However, in line with recent data on the coexistence of common and unique strategies used by viruses to perturb the human molecular system, also other viruses have a similar potential, though probably less relevant in epidemiological terms