899 research outputs found
Location and group size influence decisions in simulated intergroup encounters in banded mongooses
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
Embedding for a 3D World Spinor Equation
A generic-curved spacetime Dirac-like equation in 3D is constructed. It has,
owing to the group deunitarizing automorphism, a physically
correct unitarity and flat spacetime particle properties. The construction is
achieved by embedding vector operator , that plays a
role of Dirac's matrices, into . Decomposition of
the unitary irreducible spinorial representations gives rise to
an explicit form of the infinite matrices
Switching the stereochemical outcome of 6-endo-trig cyclizations; Synthesis of 2,6-Cis-6-substituted 4-oxopipecolic acids
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
C4 olefin conversion on reduced nickel y faujasite. Evidence for C5 olefin formation via C4 olefin disproportionation
Building empathy through a design thinking project: A case study with middle secondary schoolboys
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
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
The existence of a topological double-covering for the and
diffeomorphism groups is reviewed. These groups do not have finite-dimensional
faithful representations. An explicit construction and the classification of
all , unitary irreducible representations is presented.
Infinite-component spinorial and tensorial fields,
"manifields", are introduced. Particle content of the ladder manifields, as
given by the "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 representations, that are constructed
explicitly.Comment: 19 pages, Te
High-latitude marginal reefs support fewer but bigger corals than their tropical counterparts
Anthropogenic impacts are typically detrimental to tropical coral reefs, but the effect of increasing environmental stress and variability on the size structure of coral communities remains poorly understood. This limits our ability to effectively conserve coral reef ecosystems because size specific dynamics are rarely incorporated. Our aim is to quantify variation in the size structure of coral populations across 20 sites along a tropical-to-subtropical environmental gradient on the east coast of Australia (~ 23 to 30°S), to determine how size structure changes with a gradient of sea surface temperature, turbidity, productivity and light levels. We use two approaches: 1) linear regression with summary statistics (such as median size) as response variables, a method frequently favoured by ecologists and 2) compositional functional regression, a novel method using entire size–frequency distributions as response variables. We then predict coral population size structure with increasing environmental stress and variability. Together, we find fewer but larger coral colonies in marginal reefs, where conditions are typically more variable and stressful, than in tropical reefs. Our model predicts that coral populations may become gradually dominated by larger colonies (> 148 cm2) with increasing environmental stress. Fewer but bigger corals suggest low survival of smaller corals, slow growth, and/or poor recruitment. This finding is concerning for the future of coral reefs, as it implies that current marginal populations, or future reefs in increasingly stressful environmental conditions may have low recovery potential. We highlight the importance of continuously monitoring changes to population structure over biogeographic scales
Composition, structure and stability of RuO_2(110) as a function of oxygen pressure
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
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