591 research outputs found
The right way to kiss: directionality bias in head-turning during kissing
Humans have a bias for turning to the right in a number of settings. Here we document a bias in head-turning to the right in adult humans, as tested in the act of kissing. We investigated head-turning bias in both kiss initiators and kiss recipients for lip kissing, and took into consideration differences due to sex and handedness, in 48 Bangladeshi heterosexual married couples. We report a significant male bias in the initiation of kissing and a significant bias in head-turning to the right in both kiss initiators and kiss recipients, with a tendency among kiss recipients to match their partners’ head-turning direction. These interesting outcomes are explained by the influences of societal learning or cultural norms and the potential neurophysiological underpinnings which together offer novel insights about the mechanisms underlying behavioral laterality in humans
The role of sexual and romantic attraction in human mate preferences
Sex differences in mate preferences are ubiquitous, having been evidenced across generations and cultures.
Their prevalence and persistence have compellingly placed them in the evolutionarily adaptive context of
sexual selection. However, the psycho-biological mechanisms contributing to their generation and main-
tenance remain poorly understood. As such a mechanism, sexual attraction is assumed to guide interest,
desire, and the affinity toward specific partner features. However, whether sexual attraction can indeed
explain sex differences in partner preferences has not been explicitly tested. To better understand how sex
and sexual attraction shape mate preferences in humans we assessed how partner preferences differed
across the spectrum of sexual attraction in a sample of 479 individuals that identified as asexual, gray-sexual,
demisexual or allosexual. We further tested whether romantic attraction predicted preference profiles
better than sexual attraction. Our results show that sexual attraction accounts for highly replicable sex
differences in mate preferences for high social status and financial prospects, conscientiousness, and
intelligence; however, it does not account for the enhanced preference for physical attractiveness expressed
by men, which persists even in individuals with low sexual attraction. Instead, sex differences in physical
attractiveness preference are better explained by the degree of romantic attraction. Furthermore, effects of
sexual attraction on sex differences in partner preferences were grounded in current rather than previous
experiences of sexual attraction. Taken together, the results support the idea that contemporary sex
differences in partner preferences are maintained by several psycho-biological mechanisms that evolved
in conjunction, including not only sexual but also romantic attraction
Primate hippocampus size and organization are predicted by sociality but not diet
The hippocampus is well known for its roles in spatial navigation and memory, but it is organized into regions that have different connections and functional specializations. Notably, the region CA2 has a role in social and not spatial cognition, as is the case for the regions CA1 and CA3 that surround it. Here, we investigated the evolution of the hippocampus in terms of its size and organization in relation to the evolution of social and ecological variables in primates, namely home range, diet and different measures of group size. We found that the volumes within the whole cornu ammonis coevolve with group size, while only the volume of CA1 and subiculum can also be predicted by home range. On the other hand, diet, expressed as a shift from folivory towards frugivory, was shown to not be related to hippocampal volume. Interestingly, CA2 was shown to exhibit phylogenetic signal only against certain measures of group size, but not with ecological factors. We also found that sex differences in the hippocampus are related to body size sex dimorphism. This is in line with reports of sex differences in hippocampal volume in non-primates that are related to social structure and sex differences in behaviour. Our findings support the notion that in primates, the hippocampus is a mosaic structure evolving in line with social pressures, where certain subsections evolve in line with spatial ability too
Modelação numérica do escorregamento de armaduras em elementos de betão armado / Numerical modelling of bond-slip effects in reinforced concrete elements
Reinforced concrete (RC) framed structures subjected to seismic loading often show localized deformations at the extremities of the members associated with the slippage of reinforcing bars along their anchorage length. Despite this phenomenon being responsible for up to 40% of the total lateral deformation of RC members, the numerical simulation of this behaviour still presents several limitations. This paper introduces a modelling strategy wherein, for the first time, an explicit bond-slip model is developed to be used in connection with a fibre-based beam-column element through a zero-length link element. The proposed element adopts an advanced bond stress-slip constitutive relation capable of representing the effects of cyclic degradation or rebar yielding, among others. The numerical model is validated through a comparison with experimental results, evidencing a remarkable efficiency, accuracy and numerical stability
Theory of nuclear induced spectral diffusion: Spin decoherence of phosphorus donors in Si and GaAs quantum dots
We propose a model for spectral diffusion of localized spins in
semiconductors due to the dipolar fluctuations of lattice nuclear spins. Each
nuclear spin flip-flop is assumed to be independent, the rate for this process
being calculated by a method of moments. Our calculated spin decoherence time
ms for donor electron spins in Si:P is a factor of two longer than
spin echo decay measurements. For P nuclear spins we show that spectral
diffusion is well into the motional narrowing regime. The calculation for GaAs
quantum dots gives s depending on the quantum dot size. Our
theory indicates that nuclear induced spectral diffusion should not be a
serious problem in developing spin-based semiconductor quantum computer
architectures.Comment: 15 pages, 9 figures. Accepted for publication in Phys. Rev.
Avalanches in the Weakly Driven Frenkel-Kontorova Model
A damped chain of particles with harmonic nearest-neighbor interactions in a
spatially periodic, piecewise harmonic potential (Frenkel-Kontorova model) is
studied numerically. One end of the chain is pulled slowly which acts as a weak
driving mechanism. The numerical study was performed in the limit of infinitely
weak driving. The model exhibits avalanches starting at the pulled end of the
chain. The dynamics of the avalanches and their size and strength distributions
are studied in detail. The behavior depends on the value of the damping
constant. For moderate values a erratic sequence of avalanches of all sizes
occurs. The avalanche distributions are power-laws which is a key feature of
self-organized criticality (SOC). It will be shown that the system selects a
state where perturbations are just able to propagate through the whole system.
For strong damping a regular behavior occurs where a sequence of states
reappears periodically but shifted by an integer multiple of the period of the
external potential. There is a broad transition regime between regular and
irregular behavior, which is characterized by multistability between regular
and irregular behavior. The avalanches are build up by sound waves and shock
waves. Shock waves can turn their direction of propagation, or they can split
into two pulses propagating in opposite directions leading to transient
spatio-temporal chaos. PACS numbers: 05.70.Ln,05.50.+q,46.10.+zComment: 33 pages (RevTex), 15 Figures (available on request), appears in
Phys. Rev.
Induced vacuum energy-momentum tensor in the background of a d-2 - brane in d+1 - dimensional space-time
Charged scalar field is quantized in the background of a static d-2 - brane
which is a core of the magnetic flux lines in flat d+1 - dimensional
space-time. We find that vector potential of the magnetic core induces the
energy-momentum tensor in the vacuum. The tensor components are periodic
functions of the brane flux and holomorphic functions of space dimension. The
dependence on the distance from the brane and on the coupling to the space-time
curvature scalar is comprehensively analysed.Comment: 32 pages, 3 figures, journal version, some references adde
Characterization of Dunaliella salina strains by flow cytometry: a new approach to select carotenoid hyperproducing strains
In the present work the characterization of different strains of
Dunaliella salina from established cell culture collections and
various isolates from solar saltworks located in the Canary Island, as
well as one mutant, was carried out in order to assess the existence of
intraspecific differences and to determine the potential productivity
of each one. Morphological characteristics such as cellular size and
cellular complexity and parameters linked to cellular physiology, such
as pigment content or cellular growth rate, were determined by means of
traditional techniques as well as flow cytometry. Results showed a high
morphological and physiological intraspecific variability among the
studied strains. Results suggest that the application of the lipidic
dye Nile red allowed the development of a cytometric method faster than
the traditional techniques to select carotenoid hyperproducing strains
of microalgae
Down a rabbit hole: burrowing behaviour and larger home ranges are related to larger brains in leporids
Studies on the evolution of brain size variation usually focus on large clades encompassing broad phylogenetic groups. This risks introducing ‘noise’ in the results, often obscuring effects that might be detected in less inclusive clades. Here, we focus on a sample of endocranial volumes (endocasts) of 18 species of rabbits and hares (Lagomorpha: Leporidae), which are a discrete radiation of mammals with a suitably large range of body sizes. Using 60 individuals, we test five popular hypotheses on brain size and olfactory bulb evolution in mammals. We also address the pervasive issue of missing data, using multiple phylogenetic imputations as to conserve the full sample size for all analyses. Our analyses show that home range and burrowing behaviour are the only predictors of leporid brain size variation. Litter size, which is one of the most widely reported constraints on brain size, was unexpectedly not associated with brain size. However, a constraining effect may be masked by a strong association of litter size with temperature seasonality, warranting further study. Lastly, we show that unreasonable estimations of phylogenetic signal (Pagel’s lamba) warrant additional caution when using small sample sizes, such as ours, in comparative studies
The effects of social density, spatial density, noise, and office views on perceived personal space in the virtual workplace
Here we sought to understand how perceived personal space is influenced by a number of variables that could influence Indoor Environmental Quality (IEQ); specifically, we tested how different levels of social density, spatial density, noise presence, and type of view impact the appreciation of personal space in a shared office environment. We employed virtual reality (VR) to simulate shared and single occupancy offices and devised a novel measure of personal space estimation. We also used a traditional personal space satisfaction score. Participants experienced greater perceived personal space when (1) in a sparsely populated rather than a dense office, (2) in a private office rather than an open plan office, and (3) having any view outside of the office. We did not find an effect of the presence of noise or increased social density (with spatial density held constant) on the perception of personal space
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