2,266 research outputs found
Human Pheromones: Integrating Neuroendocrinology and Ethology
The effect of sensory input on hormones is essential to any explanation of mammalian behavior, including aspects of physical attraction. The chemical signals we send have direct and developmental effects on hormone levels in other people. Since we don't know either if, or how, visual cues might have direct and developmental effects on hormone levels in other people, the biological basis for the development of visually perceived human physical attraction is currently somewhat questionable. In contrast, the biological basis for the development of physical attraction based on chemical signals is well detailed
A Model for the Stray Light Contamination of the UVCS Instrument on SOHO
We present a detailed model of stray-light suppression in the spectrometer
channels of the Ultraviolet Coronagraph Spectrometer (UVCS) on the SOHO
spacecraft. The control of diffracted and scattered stray light from the bright
solar disk is one of the most important tasks of a coronagraph. We compute the
fractions of light that diffract past the UVCS external occulter and
non-specularly pass into the spectrometer slit. The diffracted component of the
stray light depends on the finite aperture of the primary mirror and on its
figure. The amount of non-specular scattering depends mainly on the
micro-roughness of the mirror. For reasonable choices of these quantities, the
modeled stray-light fraction agrees well with measurements of stray light made
both in the laboratory and during the UVCS mission. The models were constructed
for the bright H I Lyman alpha emission line, but they are applicable to other
spectral lines as well.Comment: 19 pages, 5 figures, Solar Physics, in pres
The evolution of plasma parameters on a coronal source surface at 2.3 Rs during solar minimum
We analyze data from the Solar and Heliospheric Observatory to produce global
maps of coronal outflow velocities and densities in the regions where the solar
wind is undergoing acceleration. The maps use UV and white light coronal data
obtained from the Ultraviolet Coronagraph Spectrometer and the Large Angle
Spectroscopic Coronagraph, respectively, and a Doppler dimming analysis to
determine the mean outflow velocities. The outflow velocities are defined on a
sphere at 2.3 Rs from Sun-center and are organized by Carrington Rotations
during the solar minimum period at the start of solar cycle 23. We use the
outflow velocity and density maps to show that while the solar minimum corona
is relatively stable during its early stages, the shrinkage of the north polar
hole in the later stages leads to changes in both the global areal expansion of
the coronal hole and the derived internal flux tube expansion factors of the
solar wind. The polar hole areal expansion factor and the flux tube expansion
factors (between the coronal base and 2.3 Rs) start out as super-radial but
then they become more nearly radial as the corona progresses away from solar
minimum. The results also support the idea that the largest flux tube expansion
factors are located near the coronal hole/streamer interface, at least during
the deepest part of the solar minimum period.Comment: 12 Figures, Accepted for publication in Ap
Mitochondrial ultrastructure and complex formation are determining factors for the mobility of OXPHOS complexes in the IMM
Alfven Wave Reflection and Turbulent Heating in the Solar Wind from 1 Solar Radius to 1 AU: an Analytical Treatment
We study the propagation, reflection, and turbulent dissipation of Alfven
waves in coronal holes and the solar wind. We start with the Heinemann-Olbert
equations, which describe non-compressive magnetohydrodynamic fluctuations in
an inhomogeneous medium with a background flow parallel to the background
magnetic field. Following the approach of Dmitruk et al, we model the nonlinear
terms in these equations using a simple phenomenology for the cascade and
dissipation of wave energy, and assume that there is much more energy in waves
propagating away from the Sun than waves propagating towards the Sun. We then
solve the equations analytically for waves with periods of hours and longer to
obtain expressions for the wave amplitudes and turbulent heating rate as a
function of heliocentric distance. We also develop a second approximate model
that includes waves with periods of roughly one minute to one hour, which
undergo less reflection than the longer-period waves, and compare our models to
observations. Our models generalize the phenomenological model of Dmitruk et al
by accounting for the solar wind velocity, so that the turbulent heating rate
can be evaluated from the coronal base out past the Alfven critical point -
that is, throughout the region in which most of the heating and acceleration
occurs. The simple analytical expressions that we obtain can be used to
incorporate Alfven-wave reflection and turbulent heating into fluid models of
the solar wind.Comment: 9 pages, 9 figures, accepted for publication in Ap
Experimental Study and Simulation of Pull-In Behavior in Hybrid Levitation Microactuator for Square-Shaped Proof Masses
- …