997 research outputs found
Thermally driven spin injection from a ferromagnet into a non-magnetic metal
Creating, manipulating and detecting spin polarized carriers are the key
elements of spin based electronics. Most practical devices use a perpendicular
geometry in which the spin currents, describing the transport of spin angular
momentum, are accompanied by charge currents. In recent years, new sources of
pure spin currents, i.e., without charge currents, have been demonstrated and
applied. In this paper, we demonstrate a conceptually new source of pure spin
current driven by the flow of heat across a ferromagnetic/non-magnetic metal
(FM/NM) interface. This spin current is generated because the Seebeck
coefficient, which describes the generation of a voltage as a result of a
temperature gradient, is spin dependent in a ferromagnet. For a detailed study
of this new source of spins, it is measured in a non-local lateral geometry. We
developed a 3D model that describes the heat, charge and spin transport in this
geometry which allows us to quantify this process. We obtain a spin Seebeck
coefficient for Permalloy of -3.8 microvolt/Kelvin demonstrating that thermally
driven spin injection is a feasible alternative for electrical spin injection
in, for example, spin transfer torque experiments
Locomotor hyperactivity in 14-3-3Zeta KO mice is associated with dopamine transporter dysfunction
Dopamine (DA) neurotransmission requires a complex series of enzymatic reactions that are tightly linked to catecholamine exocytosis and receptor interactions on pre- and postsynaptic neurons. Regulation of dopaminergic signalling is primarily achieved through reuptake of extracellular DA by the DA transporter (DAT) on presynaptic neurons. Aberrant regulation of DA signalling, and in particular hyperactivation, has been proposed as a key insult in the presentation of schizophrenia and related neuropsychiatric disorders. We recently identified 14-3-3Îś as an essential component of neurodevelopment and a central risk factor in the schizophrenia protein interaction network. Our analysis of 14-3-3Îś-deficient mice now shows that baseline hyperactivity of knockout (KO) mice is rescued by the antipsychotic drug clozapine. 14-3-3Îś KO mice displayed enhanced locomotor hyperactivity induced by the DA releaser amphetamine. Consistent with 14-3-3Îś having a role in DA signalling, we found increased levels of DA in the striatum of 14-3-3Îś KO mice. Although 14-3-3Îś is proposed to modulate activity of the rate-limiting DA biosynthesis enzyme, tyrosine hydroxylase (TH), we were unable to identify any differences in total TH levels, TH localization or TH activation in 14-3-3Îś KO mice. Rather, our analysis identified significantly reduced levels of DAT in the absence of notable differences in RNA or protein levels of DA receptors D1âD5. Providing insight into the mechanisms by which 14-3-3Îś controls DAT stability, we found a physical association between 14-3-3Îś and DAT by co-immunoprecipitation. Taken together, our results identify a novel role for 14-3-3Îś in DA neurotransmission and provide support to the hyperdopaminergic basis of pathologies associated with schizophrenia and related disorders.H Ramshaw, X Xu, EJ Jaehne, P McCarthy, Z Greenberg, E Saleh, B McClure, J Woodcock, S Kabbara, S Wiszniak, Ting-Yi Wang, C Parish, M van den Buuse, BT Baune, A Lopez and Q Schwar
Unbalanced Holographic Superconductors and Spintronics
We present a minimal holographic model for s-wave superconductivity with
unbalanced Fermi mixtures, in 2+1 dimensions at strong coupling. The breaking
of a U(1)_A "charge" symmetry is driven by a non-trivial profile for a charged
scalar field in a charged asymptotically AdS_4 black hole. The chemical
potential imbalance is implemented by turning on the temporal component of a
U(1)_B "spin" field under which the scalar field is uncharged. We study the
phase diagram of the model and comment on the eventual (non) occurrence of
LOFF-like inhomogeneous superconducting phases. Moreover, we study "charge" and
"spin" transport, implementing a holographic realization (and a generalization
thereof to superconducting setups) of Mott's two-current model which provides
the theoretical basis of modern spintronics. Finally we comment on possible
string or M-theory embeddings of our model and its higher dimensional
generalizations, within consistent Kaluza-Klein truncations and brane-anti
brane setups.Comment: 45 pages, 15 figures; v2: two paragraphs below eq. (3.1) slightly
modified, figure 5 (left) replaced, references added; v3: typos corrected,
comments added, figure 12 replace
Prognostic Factors of Long Term Disability Due to Mental Disorders: A Systematic Review
Introduction In the past few decades, mental health problems have increasingly contributed to sickness absence and long-term disability. However, little is known about prognostic factors of return to work (RTW) and disability of persons already on sick leave due to mental health problems. Understanding these factors may help to develop effective prevention and intervention strategies to shorten the duration of disability and facilitate RTW. Method We reviewed systematically current scientific evidence about prognostic factors for mental health related long term disability, RTW and symptom recovery. Searching PubMed, PsycINFO, Embase, Cinahl and Business Source Premier, we selected articles with a publication date from January 1990 to March 2009, describing longitudinal cohort studies with a follow-up period of at least 1Â year. Participants were persons on sick leave or receiving disability benefit at baseline. We assessed the methodological quality of included studies using an established criteria list. Consistent findings in at least two high quality studies were defined as strong evidence and positive findings in one high quality study were defined as limited evidence. Results Out of 796 studies, we included seven articles, all of high methodological quality describing a range of prognostic factors, according to the ICF-model categorized as health-related, personal and external factors. We found strong evidence that older age (>50Â years) is associated with continuing disability and longer time to RTW. There is limited evidence for the association of other personal factors (gender, education, history of previous sickness absence, negative recovery expectation, socio-economic status), health related (stress-related and shoulder/back pain, depression/anxiety disorder) and external i.e., job-related factors (unemployment, quality and continuity of occupational care, supervisor behavior) with disability and RTW. We found limited evidence for the association of personal/external factors (education, sole breadwinner, partial/full RTW, changing work tasks) with symptom recovery. Conclusion This systematic review identifies a number of prognostic factors, some more or less consistent with findings in related literature (mental health factors, age, history of previous sickness absence, negative recovery expectation, socio-economic status, unemployment, quality and continuity of occupational care), while other prognostic factors (gender, level of education, sole breadwinner, supervisor support) conflict with existing evidence. There is still great need for research on modifiable prognostic factors of continuing disability and RTW among benefit claimants with mental health problems. Recommendations are made as to directions and methodological quality of further research, i.e., prognostic cohort studies
A theory of first order dissipative superfluid dynamics
We determine the most general form of the equations of relativistic
superfluid hydrodynamics consistent with Lorentz invariance, time-reversal
invariance, the Onsager principle and the second law of thermodynamics at first
order in the derivative expansion. Once parity is violated, either because the
symmetry is anomalous or as a consequence of a different parity-breaking
mechanism, our results deviate from the standard textbook analysis of
superfluids. Our general equations require the specification of twenty
parameters (such as the viscosity and conductivity). In the limit of small
relative superfluid velocities we find a seven parameter set of equations. In
the same limit, we have used the AdS/CFT correspondence to compute the parity
odd contributions to the superfluid equations of motion for a generic
holographic model and have verified that our results are consistent.Comment: v1: 84+1 pages; v2: a sign error corrected, and the assumption of
time-reversal invariance made explici
Giant enhancement of spin accumulation and long-distance spin precession in metallic lateral spin valves
The nonlocal spin injection in lateral spin valves is highly expected to be
an effective method to generate a pure spin current for potential spintronic
application. However, the spin valve voltage, which decides the magnitude of
the spin current flowing into an additional ferromagnetic wire, is typically of
the order of 1 {\mu}V. Here we show that lateral spin valves with low resistive
NiFe/MgO/Ag junctions enable the efficient spin injection with high applied
current density, which leads to the spin valve voltage increased hundredfold.
Hanle effect measurements demonstrate a long-distance collective 2-pi spin
precession along a 6 {\mu}m long Ag wire. These results suggest a route to
faster and manipulable spin transport for the development of pure spin current
based memory, logic and sensing devices.Comment: 23 pages, 4 figure
X-ray emission from the Sombrero galaxy: discrete sources
We present a study of discrete X-ray sources in and around the
bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival
Chandra observations with a total exposure of ~200 ks. With a detection limit
of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30
kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler
et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS
observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray
binaries (LMXBs). We quantify the differential luminosity functions (LFs) for
both the detected GC and field LMXBs, whose power-low indices (~1.1 for the
GC-LF and ~1.6 for field-LF) are consistent with previous studies for
elliptical galaxies. With precise sky positions of the GCs without a detected
X-ray source, we further quantify, through a fluctuation analysis, the GC LF at
fainter luminosities down to 1E35 erg/s. The derived index rules out a
faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent
findings in several elliptical galaxies and the bulge of M31. On the other
hand, the 2-6 keV unresolved emission places a tight constraint on the field
LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101
sources in the halo of Sombrero. The presence of these sources cannot be
interpreted as galactic LMXBs whose spatial distribution empirically follows
the starlight. Their number is also higher than the expected number of cosmic
AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray
surveys. We suggest that either the cosmic X-ray background is unusually high
in the direction of Sombrero, or a distinct population of X-ray sources is
present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres
Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV
The azimuthal anisotropy of charged particles in PbPb collisions at
nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS
detector at the LHC over an extended transverse momentum (pt) range up to
approximately 60 GeV. The data cover both the low-pt region associated with
hydrodynamic flow phenomena and the high-pt region where the anisotropies may
reflect the path-length dependence of parton energy loss in the created medium.
The anisotropy parameter (v2) of the particles is extracted by correlating
charged tracks with respect to the event-plane reconstructed by using the
energy deposited in forward-angle calorimeters. For the six bins of collision
centrality studied, spanning the range of 0-60% most-central events, the
observed v2 values are found to first increase with pt, reaching a maximum
around pt = 3 GeV, and then to gradually decrease to almost zero, with the
decline persisting up to at least pt = 40 GeV over the full centrality range
measured.Comment: Replaced with published version. Added journal reference and DO
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
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