2,577 research outputs found
The reward value of infant facial cuteness tracks within-subject changes in women’s salivary testosterone
“Baby schema” refers to infant characteristics, such as facial cues, that
positively influence cuteness perceptions and trigger caregiving and protective
behaviors in adults. Current models of hormonal regulation of parenting
behaviors address how hormones may modulate protective behaviors and
nurturance, but not how hormones may modulate responses to infant
cuteness. To explore this issue, we investigated possible relationships
between the reward value of infant facial cuteness and within-woman changes
in testosterone, estradiol, and progesterone levels. Multilevel modeling of
these data showed that infant cuteness was more rewarding when women’s
salivary testosterone levels were high. Moreover, this within-woman effect of
testosterone was independent of the possible effects of estradiol and
progesterone and was not simply a consequence of changes in women’s
cuteness perceptions. These results suggest that testosterone may modulate
differential responses to infant facial cuteness, potentially revealing a new
route through which testosterone shapes selective allocation of parental
resources
Three-point density correlation functions in the fractional quantum Hall regime
In this paper we consider the three-particle density correlation function for
a fractional quantum Hall liquid. The study of this object is motivated by
recent experimental studies of fractional quantum Hall systems using inelastic
light scattering and phonon absorption techniques. Symmetry properties of the
correlation function are noted. An exact sum-rule is derived which this
quantity must obey. This sum-rule is used to assess the convolution
approximation that has been used to estimate the matrix elements for such
experiments. PACS Numbers: 73.40.Hm, 73.20.Mf, 72.10.DiComment: 12 pages + 1 (PS) figur
Women’s facial attractiveness is related to their body mass index, but not their salivary cortisol
Objectives: Although many theories of human facial attractiveness propose positive correlations between facial attractiveness and measures of actual health, evidence for such correlations is somewhat mixed. Here we sought to replicate a recent study reporting that women’s facial attractiveness is independently related to both their adiposity and cortisol.
Methods: Ninety-six women provided saliva samples, which were analyzed for cortisol level, and their height and weight, which were used to calculate their body mass index (BMI). A digital face image of each woman was also taken under standardized photographic conditions and rated for attractiveness.
Results: There was a significant negative correlation between women’s facial attractiveness and BMI. By contrast, salivary cortisol and facial attractiveness were not significantly correlated.
Conclusions: Our results suggest that the types of health information reflected in women's faces include qualities that are indexed by BMI, but do not necessarily include qualities that are indexed by cortisol
Testing the utility of a data-driven approach for assessing BMI from face images
Several lines of evidence suggest that facial cues of adiposity may be important for human social interaction. However, tests for quantifiable cues of body mass index (BMI) in the face have examined only a small number of facial proportions and these proportions were found to have relatively low predictive power. Here we employed a data-driven approach in which statistical models were built using principal components (PCs) derived from objectively defined shape and color characteristics in face images. The predictive power of these models was then compared with models based on previously studied facial proportions (perimeter-to-area ratio, width-to-height ratio, and cheek-to-jaw width). Models based on 2D shape-only PCs, color-only PCs, and 2D shape and color PCs combined each performed significantly and substantially better than models based on one or more of the previously studied facial proportions. A non-linear PC model considering both 2D shape and color PCs was the best predictor of BMI. These results highlight the utility of a “bottom-up”, data-driven approach for assessing BMI from face images
Microwave emission from a crystal of molecular magnets -- The role of a resonant cavity
We discuss the effects caused by a resonant cavity around a sample of a
magnetic molecular crystal (such as Mn-Ac), when a time dependent
external magnetic field is applied parallel to the easy axis of the crystal. We
show that the back action of the cavity field on the sample significantly
increases the possibility of microwave emission. This radiation process can be
supperradiance or a maser-like effect, depending on the strength of the
dephasing. Our model provides further insight to the theoretical understanding
of the bursts of electromagnetic radiation observed in recent experiments
accompanying the resonant quantum tunneling of magnetization. The experimental
findings up to now can all be explained as being a maser effect rather than
superradiance. The results of our theory scale similarly to the experimental
findings, i.e., with increasing sweep rate of the external magnetic field, the
emission peaks are shifted towards higher field values.Comment: 12 pages, 6 figures. To appear in Phys. Rev.
Intrinsic optical bistability of thin films of linear molecular aggregates: The one-exciton approximation
We perform a theoretical study of the nonlinear optical response of an
ultrathin film consisting of oriented linear aggregates. A single aggregate is
described by a Frenkel exciton Hamiltonian with uncorrelated on-site disorder.
The exciton wave functions and energies are found exactly by numerically
diagonalizing the Hamiltonian. The principal restriction we impose is that only
the optical transitions between the ground state and optically dominant states
of the one-exciton manifold are considered, whereas transitions to other
states, including those of higher exciton manifolds, are neglected. The optical
dynamics of the system is treated within the framework of truncated optical
Maxwell-Bloch equations in which the electric polarization is calculated by
using a joint distribution of the transition frequency and the transition
dipole moment of the optically dominant states. This function contains all the
statistical information about these two quantities that govern the optical
response, and is obtained numerically by sampling many disorder realizations.
We derive a steady-state equation that establishes a relationship between the
output and input intensities of the electric field and show that within a
certain range of the parameter space this equation exhibits a three-valued
solution for the output field. A time-domain analysis is employed to
investigate the stability of different branches of the three-valued solutions
and to get insight into switching times. We discuss the possibility to
experimentally verify the bistable behavior.Comment: 13 two-column pages, 8 figures, accepted to the Journal of Chemical
Physic
Coherent states for the hydrogen atom
We construct a system of coherent states for the hydrogen atom that is
expressed in terms of elementary functions. Unlike to the previous attempts in
this direction, this system possesses the properties equivalent to the most of
those for the harmonic oscillator, with modifications due to the character of
the problem.Comment: 6 pages, LATEX, using ioplppt.sty and iopfts.sty. v.2: some misprints
are corrected. To appear in J.Phys.
Interferometric Astrometry of the Low-mass Binary Gl 791.2 (= HU Del) Using Hubble Space Telescope Fine Guidance Sensor 3: Parallax and Component Masses
With fourteen epochs of fringe tracking data spanning 1.7y from Fine Guidance
Sensor 3 we have obtained a parallax (pi_abs=113.1 +- 0.3 mas) and perturbation
orbit for Gl 791.2A. Contemporaneous fringe scanning observations yield only
three clear detections of the secondary on both interferometer axes. They
provide a mean component magnitude difference, Delta V = 3.27 +- 0.10. The
period (P = 1.4731 yr) from the perturbation orbit and the semi-major axis (a =
0.963 +- 0.007 AU) from the measured component separations with our parallax
provide a total system mass M_A + M_B = 0.412 +- 0.009 M_sun. Component masses
are M_A=0.286 +- 0.006 M_sun and M_B = 0.126 +- 0.003 M_sun. Gl 791.2A and B
are placed in a sparsely populated region of the lower main sequence
mass-luminosity relation where they help define the relation because the masses
have been determined to high accuracy, with errors of only 2%.Comment: 19 pages, 5 figures. The paper is to appear in August 2000 A
Superradiance from an ultrathin film of three-level V-type atoms: Interplay between splitting, quantum coherence and local-field effects
We carry out a theoretical study of the collective spontaneous emission
(superradiance) from an ultrathin film comprised of three-level atoms with
-configuration of the operating transitions. As the thickness of the system
is small compared to the emission wavelength inside the film, the local-field
correction to the averaged Maxwell field is relevant. We show that the
interplay between the low-frequency quantum coherence within the subspace of
the upper doublet states and the local-field correction may drastically affect
the branching ratio of the operating transitions. This effect may be used for
controlling the emission process by varying the doublet splitting and the
amount of low-frequency coherence.Comment: 15 pages, 5 figure
Probing the quantum phase transition in the Dicke model through mechanical vibrations
This paper is concerned with quantum dynamics of a system coupled to a
critical reservoir. In this context, we employ the Dicke model which is known
to exhibit a super radiant quantum phase transition (QPT) and we allow one of
the mirrors to move under a linear restoring force. The electromagnetic field
couples to the movable mirror though radiation pressure just like in typical
optomechanical setups. We show that, in the thermodynamical limit, the
super-radiant phase induces a classical driving force on the mirror without
causing decoherence.Comment: 6 pages, 3 figures, final versio
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