892 research outputs found

    Location and group size influence decisions in simulated intergroup encounters in banded mongooses

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    In social species that cooperatively defend territories the decision to retreat or attack in contests between groups is likely to depend on ecological and social factors. Previous studies have emphasized the importance of the encounter location or the size of competing groups on the outcome. In addition, the identity of the intruder, whether familiar or stranger, may also play a role. To test whether the same factors affect the resident group's decisions already at the beginning of contests, we simulated intergroup encounters in banded mongooses (Mungos mungo). When spotting rival groups banded mongooses emit "screeching calls” which lead group members to bunch up. With playbacks of these calls, we tested how the groups' response was affected by the following factors: 1) the location of the playback in relation to their territory (exclusive use vs. overlap); 2) the number of resident individuals; and 3) the origin of calls (neighbor vs. stranger) used. Subjects were more likely to approach the loudspeakers and arrive within 1 m of the speakers in the exclusive use zone than in the overlap zone. Moreover, larger groups tended to be more likely to move toward the loudspeakers and were also more likely to arrive there. The origin of calls used in the playbacks did not affect the groups' responses. These findings exemplify the importance of the combined effect of location and group size on group decisions during impending intergroup contes

    SLˉ(4,R)\bar{SL}(4,R) Embedding for a 3D World Spinor Equation

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    A generic-curved spacetime Dirac-like equation in 3D is constructed. It has, owing to the SLˉ(n,R)\bar{SL}(n,R) group deunitarizing automorphism, a physically correct unitarity and flat spacetime particle properties. The construction is achieved by embedding SLˉ(3,R)\bar{SL}(3,R) vector operator XμX_{\mu}, that plays a role of Dirac's γμ\gamma_{\mu} matrices, into SLˉ(4,R)\bar{SL}(4,R). Decomposition of the unitary irreducible spinorial SLˉ(4,R)\bar{SL}(4,R) representations gives rise to an explicit form of the infinite XμX_{\mu} matrices

    Switching the stereochemical outcome of 6-endo-trig cyclizations; Synthesis of 2,6-Cis-6-substituted 4-oxopipecolic acids

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    A base-mediated 6-endo-trig cyclization of readily accessible enone-derived α-amino acids has been developed for the direct synthesis of novel 2,6-cis-6- substituted-4-oxo-L-pipecolic acids. A range of aliphatic and aryl side chains were tolerated by this mild procedure to give the target compounds in good overall yields. Molecular modeling of the 6-endo-trig cyclization allowed some insight as to how these compounds were formed, with the enolate intermediate generated via an equilibrium process, followed by irreversible tautomerization/neutralization providing the driving force for product formation. Stereoselective reduction and deprotection of the resulting 2,6-cis-6-substituted 4-oxo-L-pipecolic acids to the corresponding 4-hydroxy-L-pipecolic acids was also performed

    Building empathy through a design thinking project: A case study with middle secondary schoolboys

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    Adolescents' empathy is an essential socio-emotional concept that helps mediate friendships and family relationships. Year 10 boys, aged 14-15 years, were invited to participate in a five-day experiential education program (Design Week) based on a social equity challenge using a Design Thinking concept. Students worked in small groups, mentored by experts. Student groups developed innovative solutions to support women who experienced domestic and family violence. As a key outcome, students' empathy measured by the Comprehensive State Empathy Scale increased significantly from a baseline of 63% to 75% at post-test, representing a large effect size (d= 1.06). Six empathy subscale factors were also significantly increased (p= <0.05). The program was feasible and was rated by teachers and students as engaging, relevant to learning, and learning about complex social issues. This paper presents a case study of the Design Week program, shown to be worthy of further testing with secondary school adolescents

    Comparisons of Flame Surface Density Measurements with Direct Numerical Simulations of a lean Methane-air Flame in High-intensity Turbulence

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    The turbulent burning velocity of premixed flames exhibits a non-linear variation under increasing turbulence intensity of the unburned mixture. This phenomenon, known as the bending effect, has not been fully explained to date. A key aspect is the mechanism responsible for the observed departure from linearity. Experimental measurements of spherically-expanding flame kernels [Bradley et al. (2013), Proc.Combust.Inst., 34:1519–1526.] point towards local quenching as the primary mechanism of inhibition (bending). On the other hand, recent Direct Numerical Simulations of statistically-planar flames [Nivarti et al. (2017), Proc.Combust.Inst. , 36:(in press).] indicate that bending might be achieved in the absence of local quenching. The present study investigates the underlying mechanisms by comparing DNS data with experimental measurements of a lean premixed methane-air flame in high-intensity turbulence

    World Spinors - Construction and Some Applications

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    The existence of a topological double-covering for the GL(n,R)GL(n,R) and diffeomorphism groups is reviewed. These groups do not have finite-dimensional faithful representations. An explicit construction and the classification of all SLˉ(n,R)\bar{SL}(n,R), n=3,4n=3,4 unitary irreducible representations is presented. Infinite-component spinorial and tensorial SLˉ(4,R)\bar{SL}(4,R) fields, "manifields", are introduced. Particle content of the ladder manifields, as given by the SLˉ(3,R)\bar{SL}(3,R) "little" group is determined. The manifields are lifted to the corresponding world spinorial and tensorial manifields by making use of generalized infinite-component frame fields. World manifields transform w.r.t. corresponding Diffˉ(4,R)\bar{Diff}(4,R) representations, that are constructed explicitly.Comment: 19 pages, Te

    Composition, structure and stability of RuO_2(110) as a function of oxygen pressure

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    Using density-functional theory (DFT) we calculate the Gibbs free energy to determine the lowest-energy structure of a RuO_2(110) surface in thermodynamic equilibrium with an oxygen-rich environment. The traditionally assumed stoichiometric termination is only found to be favorable at low oxygen chemical potentials, i.e. low pressures and/or high temperatures. At realistic O pressure, the surface is predicted to contain additional terminal O atoms. Although this O excess defines a so-called polar surface, we show that the prevalent ionic model, that dismisses such terminations on electrostatic grounds, is of little validity for RuO_2(110). Together with analogous results obtained previously at the (0001) surface of corundum-structured oxides, these findings on (110) rutile indicate that the stability of non-stoichiometric terminations is a more general phenomenon on transition metal oxide surfaces.Comment: 12 pages including 5 figures. Submitted to Phys. Rev. B. Related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

    STAT2 deficiency and susceptibility to viral illness in humans

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    Severe infectious disease in children may be a manifestation of primary immunodeficiency. These genetic disorders represent important experiments of nature with the capacity to elucidate nonredundant mechanisms of human immunity. We hypothesized that a primary defect of innate antiviral immunity was responsible for unusually severe viral illness in two siblings; the proband developed disseminated vaccine strain measles following routine immunization, whereas an infant brother died after a 2-d febrile illness from an unknown viral infection. Patient fibroblasts were indeed abnormally permissive for viral replication in vitro, associated with profound failure of type I IFN signaling and absence of STAT2 protein. Sequencing of genomic DNA and RNA revealed a homozygous mutation in intron 4 of STAT2 that prevented correct splicing in patient cells. Subsequently, other family members were identified with the same genetic lesion. Despite documented infection by known viral pathogens, some of which have been more severe than normal, surviving STAT2-deficient individuals have remained generally healthy, with no obvious defects in their adaptive immunity or developmental abnormalities. These findings imply that type I IFN signaling [through interferon-stimulated gene factor 3 (ISGF3)] is surprisingly not essential for host defense against the majority of common childhood viral infections
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