1,117 research outputs found
Time perspective, depression, and substance misuse among the homeless
Using the Zimbardo Time Perspective Inventory (ZTPI; P. G. Zimbardo & J. N. Boyd, 1999), the authors found that homeless people, in comparison with a control group, had a significantly more negative outlook concerning their past and present as evinced by high Past-Negative and Present-Fatalistic scores and low Past-Positive scores on the ZTPI. However, the homeless individuals were almost indistinguishable from control participants on measures of Present-Hedonism and Future thinking. The homeless individuals had significantly higher levels of depression, with 31 out of 50 (62%) reaching criteria for probable depression. However, this finding was unrelated to their atypical time perspective. There was no significant relation between substance misuse and time perspective. Despite their current difficulties, including depression and drug abuse, the homeless individuals maintained a propensity toward future thinking characterized by striving to achieve their goals.
Precise measurements of radio-frequency magnetic susceptibility in (anti)ferromagnetic materials
Dynamic magnetic susceptibility, , was studied in several intermetallic
materials exhibiting ferromagnetic, antiferromagnetic and metamagnetic
transitions. Precise measurements by using a 14 MHz tunnel diode oscillator
(TDO) allow detailed insight into the field and temperature dependence of
. In particular, local moment ferromagnets show a sharp peak in
near the Curie temperature, . The peak amplitude decreases and shifts to
higher temperatures with very small applied dc fields. Anisotropic measurements
of CeVSb show that this peak is present provided the magnetic easy axis is
aligned with the excitation field. In a striking contrast, small moment,
itinerant ferromagnets (i.e., ZrZn) show a broad maximum in that
responds differently to applied field. We believe that TDO measurements provide
a very sensitive way to distinguish between local and itinerant moment magnetic
orders. Local moment antiferromagnets do not show a peak at the N\'eel
temperature, , but only a sharp decrease of below due to the
loss of spin-disorder scattering changing the penetration depth of the ac
excitation field. Furthermore, we show that the TDO is capable of detecting
changes in spin order as well as metamagnetic transitions. Finally, critical
scaling of in the vicinity of is discussed in CeVSb and
CeAgSb
Breakdown of correspondence in chaotic systems: Ehrenfest versus localization times
Breakdown of quantum-classical correspondence is studied on an experimentally
realizable example of one-dimensional periodically driven system. Two relevant
time scales are identified in this system: the short Ehrenfest time t_h and the
typically much longer localization time scale T_L. It is shown that
surprisingly weak modification of the Hamiltonian may eliminate the more
dramatic symptoms of localization without effecting the more subtle but
ubiquitous and rapid loss of correspondence at t_h.Comment: 4 pages, 5 figures, replaced with a version submitted to PR
Stable isotope signatures reveal small-scale spatial separation in populations of European sea bass
Scientific information about European sea bass (Dicentrarchus labrax) stocks in NE Atlantic is limited and a more accurate definition of the stock boundaries in the area is required to improve assessment and management advice. Here we study the connectivity and movement patterns of European sea bass in Wales (UK) using the stable isotope (δ13C and δ15N) composition of their scales. Analysis of fish scale δ13C and δ15N values in the last growing season was performed on 189 adult sea bass caught at nine coastal feeding grounds. Fish >50 cm total length (TL) caught in estuaries had very low δ13C and this is characteristic of fresh water (organic/soil) input, indicating the primary use of estuaries as feeding areas. A random forest classification model was used to test if there was a difference in δ15N and δ13C values between north, mid and south Wales and whether it was possible to correctly assign the fish to the area where it was caught. This analysis was restricted to fish of a similar size range (40-50 cm TL) caught in open coastal areas (n=156). The random forest classification model showed that about 75% of the fish could be correctly assigned to their collection region based on their isotope composition. The majority of the misclassifications of fish were fish from north Wales classifying to mid Wales and vice versa, while the majority of fish from south Wales were correctly assigned (80%). Our findings suggest that two sub-populations of sea bass in Welsh waters use separate feeding grounds (south vs. mid/north Wales), and may need separate management
Short proofs of some extremal results III
We prove a selection of results from different areas of extremal combinatorics, including complete or partial solutions to a number of open problems. These results, coming mainly from extremal graph theory and Ramsey theory, have been collected together because in each case the relevant proofs are reasonably short
Two Loop R-Symmetry Breaking
We analyze two loop quantum corrections for pseudomoduli in O'Raifeartaigh
like models. We argue that R-symmetry can be spontaneously broken at two loop
in non supersymmetric vacua. We provide a basic example with this property. We
discuss on phenomenological applications.Comment: 13 pages, 5 figures, JHEP3.cls, reference adde
Radiative Corrections to One-Photon Decays of Hydrogenic Ions
Radiative corrections to the decay rate of n=2 states of hydrogenic ions are
calculated. The transitions considered are the M1 decay of the 2s state to the
ground state and the E1(M2) decays of the and states to
the ground state. The radiative corrections start in order , but the method used sums all orders of . The leading
correction for the E1 decays is calculated and compared
with the exact result. The extension of the calculational method to parity
nonconserving transitions in neutral atoms is discussed.Comment: 22 pages, 2 figure
R-symmetric gauge mediation
We present a version of Gauge Mediated Supersymmetry Breaking which preserves
an R-symmetry - the gauginos are Dirac particles, the A-terms are zero, and
there are four Higgs doublets. This offers an alternative way for gauginos to
acquire mass in the supersymmetry-breaking models of Intriligator, Seiberg, and
Shih. We investigate the possibility of using R-symmetric gauge mediation to
realize the spectrum and large sfermion mixing of the model of Kribs, Poppitz,
and Weiner.Comment: 26+ pages, 3 figures, BIBTEX; v2 published version: references added,
paragraph on spectrum running removed, section added on adjoint scalar
masses, clarification of the meaning of Table 3 adde
Analytical and numerical investigation of escape rate for a noise driven bath
We consider a system-reservoir model where the reservoir is modulated by an
external noise. Both the internal noise of the reservoir and the external noise
are stationary, Gaussian and are characterized by arbitrary decaying
correlation functions. Based on a relation between the dissipation of the
system and the response function of the reservoir driven by external noise we
numerically examine the model using a full bistable potential to show that one
can recover the turn-over features of the usual Kramers' dynamics when the
external noise modulates the reservoir rather than the system directly. We
derive the generalized Kramers' rate for this nonequilibrium open system. The
theoretical results are verified by numerical simulation.Comment: Revtex, 25 pages, 5 figures. To appear in Phys. Rev.
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