54,481 research outputs found
Influence of quantum confinement on the ferromagnetism of (Ga,Mn)As diluted magnetic semiconductor
We investigate the effect of quantum confinement on the ferromagnetism of
diluted magnetic semiconductor GaMnAs using a combination of
tight-binding and density functional methods. We observe strong majority-spin
Mn -As hybridization, as well as half metallic behavior, down to sizes
as small as 20 \AA in diameter. Below this critical size, the doped holes are
self-trapped by the Mn-sites, signalling both valence and electronic
transitions. Our results imply that magnetically doped III-V nanoparticles will
provide a medium for manipulating the electronic structure of dilute magnetic
semiconductors while conserving the ferromagnetic properties and even enhancing
it in certain size regime.Comment: 4 pages, 3 figure
Polarization Properties of A Multi-Moded Concentrator
We present the design and performance of a non-imaging concentrator for use
in broad-band polarimetry at millimeter through submillimeter wavelengths. A
rectangular geometry preserves the input polarization state as the concentrator
couples f/2 incident optics to a 2 pi sr detector. Measurements of the co-polar
and cross-polar beams in both the few-mode and highly over-moded limits agree
with a simple model based on mode truncation. The measured co-polar beam
pattern is nearly independent of frequency in both linear polarizations. The
cross-polar beam pattern is dominated by a uniform term corresponding to
polarization efficiency 94%. After correcting for efficiency, the remaining
cross-polar response is -18 dB.Comment: 9 pages including 8 figures. Accepted for publication in the Journal
of the Optical Society of America
Examining the role of mental health and clinical issues within talent development
Although significant research supports the association between physical activity and mental wellbeing, current literature acknowledges that athletes are no less susceptible to mental illness than the general population. Despite welcomed initiatives aimed at improving mental health within elite sport, these programs often fail to target young athletes; an important concern given that the genesis of many mental illnesses are recognized to occur during this critical period. Given the importance of early intervention and effective treatment, and the potentially devastating consequences of clinical issues going undiagnosed, the implications for talent identification and development become obvious. With this in mind, this study sought to examine the range of mental health issues that may impact upon developing athletes and potential consequences for the development process, specific risk and protective factors associated with talent development, along with an examination of current practices concerning the identification of mental health issues in such environments. Qualitative interviews were conducted with purposively sampled clinicians (n = 8) experienced in working with adolescents and/or young athletes. Inductive content analysis was undertaken, identifying four main themes: key behavioral indicators; associated risk factors; associated protective factors; and issues around identification and diagnosis. Key behavioral indicators included behavioral change, along with behaviors associated with eating disorders, anxiety and depression. Risk factors centered on family background, the performance environment, and issues surrounding adolescence. Protective factors were primarily social in nature. Finally, a lack of awareness and understanding of clinical issues, multiple causes of symptoms, non-disclosure and the need for triangulation of assessment were identified. The need for improved identification and intervention strategies was apparent, with coaches identified as well placed to detect general ‘warning signs’ such as behavioral change. Short of integrating trained clinicians into talent development environments, as part of a triangulation process, ecologically validated assessment tools – coupled with appropriate training and signposting – could offer a practical way of flagging potential issues in developing athletes. The need for the development of such an instrument is therefore apparent. Finally, education around the influential role of family is also recommended in order to promote the protective elements and mitigate risk factors
INTERP3: A computer routine for linear interpolation of trivariate functions defined by nondistinct unequally spaced variables
A report on the computer routine INTERP3 is presented. The routine is designed to linearly interpolate a variable which is a function of three independent variables. The variables within the parameter arrays do not have to be distinct, or equally spaced, and the array variables can be in increasing or decreasing order
Helioseismic Ring Analysis of CME Source Regions
We apply the ring diagram technique to source regions of halo coronal mass
ejections (CMEs) to study changes in acoustic mode parameters before, during,
and after the onset of CMEs. We find that CME regions associated with a low
value of magnetic flux have line widths smaller than the quiet regions implying
a longer life-time for the oscillation modes. We suggest that this criterion
may be used to forecast the active regions which may trigger CMEs.Comment: Accepted for publication in J. Astrophys. Astr. Also available at
http://www2.nso.edu/staff/sushant/paper.htm
Robust CNOT gates from almost any interaction
There are many cases where the interaction between two qubits is not
precisely known, but single qubit operations are available. In this paper we
show how, regardless of an incomplete knowledge of the strength or form of the
interaction between two qubits, it is often possible to construct a CNOT gate
which has arbitrarily high fidelity. In particular, we show that oscillations
in the strength of the exchange interaction in solid state Si and Ge structures
are correctable.Comment: 5 pages, 2 figure
Climate Ready Estuaries - COAST in Action: 2012 Projects from Maine and New Hampshire
In summer 2011 the US EPA’s Climate Ready Estuaries program awarded funds to the Casco Bay Estuary Partnership (CBEP) in Portland, Maine, and the Piscataqua Region Estuaries Partnership (PREP) in coastal New Hampshire, to further develop and use COAST (COastal Adaptation to Sea level rise Tool) in their sea level rise adaptation planning processes. The New England Environmental Finance Center worked with municipal staff, elected officials, and other stakeholders to select specific locations, vulnerable assets, and adaptation actions to model using COAST. The EFC then collected the appropriate base data layers, ran the COAST simulations, and provided visual, numeric, and presentation-based products in support of the planning processes underway in both locations. These products helped galvanize support for the adaptation planning efforts. Through facilitated meetings they also led to stakeholders identifying specific action steps and begin to determine how to implement them
Cosmological Constraints from Moments of the Thermal Sunyaev-Zel'dovich Effect
In this paper, we explain how moments of the thermal Sunyaev-Zel'dovich (tSZ)
effect can constrain both cosmological parameters and the astrophysics of the
intracluster medium (ICM). As the tSZ signal is strongly non-Gaussian, higher
moments of tSZ maps contain useful information. We first calculate the
dependence of the tSZ moments on cosmological parameters, finding that higher
moments scale more steeply with sigma_8 and are sourced by more massive galaxy
clusters. Taking advantage of the different dependence of the variance and
skewness on cosmological and astrophysical parameters, we construct a
statistic, ||/^1.4, which cancels much of the dependence on cosmology
(i.e., sigma_8) yet remains sensitive to the astrophysics of intracluster gas
(in particular, to the gas fraction in low-mass clusters). Constraining the ICM
astrophysics using this statistic could break the well-known degeneracy between
cosmology and gas physics in tSZ measurements, allowing for tight constraints
on cosmological parameters. Although detailed simulations will be needed to
fully characterize the accuracy of this technique, we provide a first
application to data from the Atacama Cosmology Telescope and the South Pole
Telescope. We estimate that a Planck-like full-sky tSZ map could achieve a <1%
constraint on sigma_8 and a 1-sigma error on the sum of the neutrino masses
that is comparable to the existing lower bound from oscillation measurements.Comment: 11 pages, 12 figures, to be submitted to Phys. Rev. D; v2: 14 pages,
16 figures, matches PRD accepted version (changes from v1 include additional
calculations with primordial non-Gaussianity and a new appendix discussing
the tSZ kurtosis
Pressure-tuned First-order Phase Transition and Accompanying Resistivity Anomaly in CeZn_{1-\delta}Sb_{2}
The Kondo lattice system CeZn_{0.66}Sb_{2} is studied by the electrical
resistivity and ac magnetic susceptibility measurements at several pressures.
At P=0 kbar, ferromagnetic and antiferromagnetic transitions appear at 3.6 and
0.8 K, respectively. The electrical resistivity at T_N dramatically changes
from the Fisher-Langer type (ferromagnetic like) to the Suzaki-Mori type near
17 kbar, i.e., from a positive divergence to a negative divergence in the
temperature derivative of the resistivity. The pressure-induced SM type
anomaly, which shows thermal hysteresis, is easily suppressed by small magnetic
field (1.9 kOe for 19.8 kbar), indicating a weakly first-order nature of the
transition. By subtracting a low-pressure data set, we directly compare the
resistivity anomaly with the SM theory without any assumption on backgrounds,
where the negative divergence in d\rho/dT is ascribed to enhanced critical
fluctuations in the presence of superzone gaps.Comment: 5 pages, 4 figures; journal-ref adde
- …