316 research outputs found
Sexuality and the drive for muscularity: evidence of associations among British men
Previous studies have documented associations between sexuality and body image, but the directionality of this association is unclear among men. This study examined whether men's drive for muscularity can be considered a correlate of their sexuality. A community-based sample of 292 heterosexual men from London, UK, completed a survey consisting of measures of drive for muscularity, sociosexuality, sexual assertiveness, sexual esteem, and sexual sensation seeking. A multiple regression analysis showed that greater drive for muscularity was predicted by more unrestricted sociosexuality (i.e., a greater proclivity for short-term, transient relationships), greater sexual sensation seeking, and greater sexual assertiveness, once the effects of participant age and body mass index had been accounted for. Possible avenues for intervention based on a sex-positive approach are discussed in conclusion
A- and B-Exciton Photoluminescence Intensity Ratio as a Measure of Sample Quality for Transition Metal Dichalcogenide Monolayers
The photoluminescence (PL) in monolayer transition metal dichalcogenides
(TMDs) is dominated by recombination of electrons in the conduction band with
holes in the spin-orbit split valence bands, and there are two distinct
emission features referred to as the A-peak (ground state exciton) and B-peak
(higher spin-orbit split state). The intensity ratio of these two features
varies widely and several contradictory interpretations have been reported. We
analyze the room temperature PL from MoS2, MoSe2, WS2, and WSe2 monolayers and
show that these variations arise from differences in the non-radiative
recombination associated with defect densities. Hence, the relative intensities
of the A- and B-emission features can be used to qualitatively asses the
non-radiative recombination, and thus the quality of the sample. A low B/A
ratio is indicative of low defect density and high sample quality. Emission
from TMD monolayers is governed by unique optical selection rules which make
them promising materials for valleytronic operations. We observe a notably
higher valley polarization in the B-exciton relative to the A-exciton. The high
polarization is a consequence of the shorter B-exciton lifetime resulting from
rapid relaxation of excitons from the B-exciton to the A-exciton of the valence
band.Comment: Final version is published online at APL Material
Magneto-reflection spectroscopy of monolayer transition-metal dichalcogenide semiconductors in pulsed magnetic fields
We describe recent experimental efforts to perform polarization-resolved
optical spectroscopy of monolayer transition-metal dichalcogenide
semiconductors in very large pulsed magnetic fields to 65 tesla. The
experimental setup and technical challenges are discussed in detail, and
temperature-dependent magneto-reflection spectra from atomically thin tungsten
disulphide (WS) are presented. The data clearly reveal not only the valley
Zeeman effect in these 2D semiconductors, but also the small quadratic exciton
diamagnetic shift from which the very small exciton size can be directly
inferred. Finally, we present model calculations that demonstrate how the
measured diamagnetic shifts can be used to constrain estimates of the exciton
binding energy in this new family of monolayer semiconductors.Comment: PCSI-43 conference (Jan. 2016; Palm Springs, CA
Exciton Diamagnetic Shifts and Valley Zeeman Effects in Monolayer WS and MoS to 65 Tesla
We report circularly-polarized optical reflection spectroscopy of monolayer
WS and MoS at low temperatures (4~K) and in high magnetic fields to
65~T. Both the A and the B exciton transitions exhibit a clear and very similar
Zeeman splitting of approximately 230~eV/T (), providing
the first measurements of the valley Zeeman effect and associated -factors
in monolayer transition-metal disulphides. These results complement and are
compared with recent low-field photoluminescence measurements of valley
degeneracy breaking in the monolayer diselenides MoSe and WSe. Further,
the very large magnetic fields used in our studies allows us to observe the
small quadratic diamagnetic shifts of the A and B excitons in monolayer WS
(0.32 and 0.11~eV/T, respectively), from which we calculate exciton
radii of 1.53~nm and 1.16~nm. When analyzed within a model of non-local
dielectric screening in monolayer semiconductors, these diamagnetic shifts also
constrain and provide estimates of the exciton binding energies (410~meV and
470~meV for the A and B excitons, respectively), further highlighting the
utility of high magnetic fields for understanding new 2D materials.Comment: 9 pages, 5 figure
Heat content of the Arabian Sea Mini Warm Pool is increasing
© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Atmospheric Science Letters 17 (2016): 39-42, doi:10.1002/asl.596.Sea surface temperature in the Arabian Sea Mini Warm Pool has been suggested to be one of the factors that affects the Indian summer monsoon. In this paper, we analyze the annual ocean heat content (OHC) of this region during 1993–2010, using in situ data, satellite observations, and a model simulation. We find that OHC increases significantly in the region during this period relative to the north Indian Ocean, and propose that this increase could have caused the decrease in Indian Summer Monsoon Rainfall that occurred at the same time
Proximity-enhanced valley Zeeman splitting at the WS/graphene interface
The valley Zeeman physics of excitons in monolayer transition metal
dichalcogenides provides valuable insight into the spin and orbital degrees of
freedom inherent to these materials. Being atomically-thin materials, these
degrees of freedom can be influenced by the presence of adjacent layers, due to
proximity interactions that arise from wave function overlap across the 2D
interface. Here, we report 60 T magnetoreflection spectroscopy of the A- and B-
excitons in monolayer WS, systematically encapsulated in monolayer
graphene. While the observed variations of the valley Zeeman effect for the A-
exciton are qualitatively in accord with expectations from the bandgap
reduction and modification of the exciton binding energy due to the
graphene-induced dielectric screening, the valley Zeeman effect for the B-
exciton behaves markedly different. We investigate prototypical WS/graphene
stacks employing first-principles calculations and find that the lower
conduction band of WS at the valleys (the band) is strongly
influenced by the graphene layer on the orbital level. This leads to variations
in the valley Zeeman physics of the B- exciton, consistent with the
experimental observations. Our detailed microscopic analysis reveals that the
conduction band at the point of WS mediates the coupling between
and graphene due to resonant energy conditions and strong coupling to the Dirac
cone. Our results therefore expand the consequences of proximity effects in
multilayer semiconductor stacks, showing that wave function hybridization can
be a multi-step process with different bands mediating the interlayer
interactions. Such effects can be exploited to resonantly engineer the
spin-valley degrees of freedom in van der Waals and moir\'e heterostructures.Comment: 14 pages, 6 figures, 3 table
Crummer SunTrust Portfolio Recommendations: Crummer Investment Management [2016]
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