596 research outputs found
The integrated motivational–volitional model of suicidal behaviour
Suicide is a major public health concern accounting for 800 000 deaths globally each year. Although there have been many advances in understanding suicide risk in recent decades, our ability to predict suicide is no better now than it was 50 years ago. There are many potential explanations for this lack of progress, but the absence, until recently, of comprehensive theoretical models that predict the emergence of suicidal ideation distinct from the transition between suicidal ideation and suicide attempts/suicide is key to this lack of progress. The current article presents the integrated motivational–volitional (IMV) model of suicidal behaviour, one such theoretical model. We propose that defeat and entrapment drive the emergence of suicidal ideation and that a group of factors, entitled volitional moderators (VMs), govern the transition from suicidal ideation to suicidal behaviour. According to the IMV model, VMs include access to the means of suicide, exposure to suicidal behaviour, capability for suicide (fearlessness about death and increased physical pain tolerance), planning, impulsivity, mental imagery and past suicidal behaviour. In this article, we describe the theoretical origins of the IMV model, the key premises underpinning the model, empirical tests of the model and future research directions
Ground state and bias current induced rearrangement of semifluxons in 0-pi long Josephson junctions
We investigate numerically a long Josephson junction with several phase
pi-discontinuity points. Such junctions are usually fabricated as a ramp
between an anisotropic cuprate superconductor like YBCO and an isotropic metal
superconductor like Nb. From the top, they look like zigzags with pi-jumps of
the Josephson phase at the corners. These pi-jumps, at certain conditions, lead
to the formation of half-integer flux quanta, which we call semifluxons (SF),
pinned at the corners. We show (a) that the spontaneous formation of SFs
depends on the junction length, (b) that the ground state without SFs can be
converted to a state with SFs by applying a bias current, (c) that the SF
configuration can be rearranged by the bias current. All these effects can be
observed using a SQUID microscope.Comment: ~8 pages, 6 figures, submitted to PR
Robust dx2-y2 pairing symmetry in high-temperature superconductors
Although initially quite controversial, it has been widely accepted that the
Cooper pairs in optimally doped cuprate superconductors have predominantly
dx2-y2 wavefunction symmetry. The controversy has now shifted to whether the
high-Tc pairing symmetry changes away from optimal doping. Here we present
phase-sensitive tricrystal experiments on three cuprate systems:
Y0.7Ca0.3Ba2Cu3O7-x (Ca-doped Y-123), La2-xSrxCuO4 (La-214) and Bi2Sr2CaCu2O8+x
(Bi-2212),with doping levels covering the underdoped, optimal and overdoped
regions. Our work implies that time-reversal invariant, predominantly dx2-y2
pairing symmetry is robust over a large variation in doping, and underscores
the important role of on-site Coulomb repulsion in the making of
high-temperature superconductivity.Comment: 4 pages, 4 figure
Marketing dairy products in southwest Missouri
Cover title.Includes bibliographical references
Comments on the International Accounting Standards Committee (IASC) Discussion Paper entitled, Shaping IASC for the Future, dated December 1998
https://egrove.olemiss.edu/aicpa_guides/2614/thumbnail.jp
Evidence for Thermally Activated Spontaneous Fluxoid Formation in Superconducting Thin-Film Rings
We have observed spontaneous fluxoid generation in thin-film rings of the
amorphous superconductor MoSi, cooled through the normal-superconducting
transition, as a function of quench rate and externally applied magnetic field,
using a variable sample temperature scanning SQUID microscope. Our results can
be explained using a model of freezout of thermally activated fluxoids,
mediated by the transport of bulk vortices across the ring walls. This
mechanism is complementary to a mechanism proposed by Kibble and Zurek, which
only relies on causality to produce a freezout of order parameter fluctuations.Comment: 4 pages, 3 figure
Phase-sensitive Evidence for d-wave Pairing Symmetry in Electron-doped Cuprate Superconductors
We present phase-sensitive evidence that the electron-doped cuprates
Nd1.85Ce0.15CuO4-y (NCCO) and Pr1.85Ce0.15CuO4-y (PCCO) have d-wave pairing
symmetry. This evidence was obtained by observing the half-flux quantum effect,
using a scanning SQUID microscope, in c-axis oriented films of NCCO or PCCO
epitaxially grown on tricrystal [100] SrTiO3 substrates designed to be
frustrated for a d(x2-y2) order parameter. Samples with two other
configurations, designed to b unfrustrated for a d-wave superconductor, do not
show the half-flux quantum effect.Comment: 4 pages, Latex, 4 figure
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