1,289 research outputs found
Discrimination, Coping, and Depression among Black Men Who Have Sex with Men
Black men who have sex with men (BMSM) have elevated risk for depression compared to the general population. BMSM’s capacity to cope with these experiences is not well understood. Increased understanding of how multiple forms of discrimination contribute to depression and how BMSM cope with discrimination can better inform interventions. Data come from 3,510 BMSM who attended Black Pride events in six U.S. cities from 2015-2017. Participants completed a health survey that ascertained their psychosocial health and resiliency profiles. Using multivariable logistic regression models, we tested the associations between type-specific discrimination (race, sexuality, HIV status) and depression. We then conducted sub-analyses to determine if coping attenuated the association between type-specific discrimination and depression. Our findings indicated that increased odds of depression among BMSM were associated with discrimination based on race (aOR=1.38, 95% CI = 1.08-1.76), sexual orientation (aOR=1.32, 95% CI = 1.01-1.72), and HIV status (aOR=1.53, 95% CI = 1.08-2.17). Sub-analyses indicated coping had inconsistent moderation effects between type-specific discrimination and depression. Our findings demonstrate that impact of various forms of discrimination on BMSM’s mental health and the mitigating role of coping. Interventions should seek to address depression by reducing experiences of discrimination and building coping resiliency
Multi-band superconductivity in LaFeAsO_{0.9}F_{0.1} single crystals probed by high-field vortex torque magnetometry
To probe manifestations of multiband superconductivity in oxypnictides, we
measured the angular dependence of the magnetic torque in the
mixed state of LaOFFeAs single crystals as a function of
temperature and magnetic fields up to 18 T. The paramagnetic
contribution of the Fe ions is properly treated in order to extract the
effective mass anisotropy parameter from
. We show that depends strongly on both and ,
reaching a maximum value of 10 followed by a decrease towards values
close to 1 as is lowered. The observed field dependencies of the London
penetration depth and suggest the onset of suppression
of a superconducing gap at .Comment: 7 pages, 7 figure
Quasiparticle relaxation dynamics in spin-density-wave and superconducting SmFeAsO_{1-x}F_{x} single crystals
We investigate the quasiparticle relaxation and low-energy electronic
structure in undoped SmFeAsO and near-optimally doped SmFeAsO_{0.8}F_{0.2}
single crystals - exhibiting spin-density wave (SDW) ordering and
superconductivity respectively - using pump-probe femtosecond spectroscopy. In
the undoped single crystals a single relaxation process is observed, showing a
remarkable critical slowing down of the QP relaxation dynamics at the SDW
transition temperature T_{SDW}\simeq125{K}. In the superconducting (SC)
crystals multiple relaxation processes are present, with distinct SC state
quasiparticle recombination dynamics exhibiting a BCS-like T-dependent
superconducting gap, and a pseudogap (PG)-like feature with an onset above 180K
indicating the existence of a pseudogap of magnitude
2\Delta_{\mathrm{PG}}\simeq120 meV above T_{\mathrm{c}}. From the pump-photon
energy dependence we conclude that the SC state and PG relaxation channels are
independent, implying the presence of two separate electronic subsystems. We
discuss the data in terms of spatial inhomogeneity and multi-band scenarios,
finding that the latter is more consistent with the present data.Comment: Replaced by the correct versio
Magnetic phase diagram of Ca-substituted EuFeAs
The simultaneous presence of a Fe-related spin-density wave and
antiferromagnetic order of Eu moments ranks EuFeAs among the
most interesting parent compounds of iron-based pnictide superconductors. Here
we explore the consequences of the dilution of Eu magnetic lattice
through on-site Ca substitution. By employing macro- and microscopic
techniques, including electrical transport and magnetometry, as well as
muon-spin spectroscopy, we study the evolution of Eu magnetic order in both the
weak and strong dilution regimes, achieved for Ca concentration and 0.43, respectively. We demonstrate the localized character of the
Eu antiferromagnetism mediated via RKKY interactions, in contrast with the
largely itinerant nature of Fe magnetic interactions. Our results suggest a
weak coupling between the Fe and Eu magnetic sublattices and a rapid decrease
of the Eu magnetic interaction strength upon Ca substitution. The latter is
confirmed both by the depression of the ordering temperature of the Eu
moments, , and the decrease of magnetic volume fraction with
increasing . We establish that, similarly to the EuFeAs
parent compound, the investigated Ca-doped compounds have a twinned structure
and undergo a permanent detwinning upon applying an external magnetic field
Single crystal of superconducting SmFeAsO1-xFy grown at high pressure
Single crystals of SmFeAsO1-xFy of a size up to 120 micrometers have been
grown from NaCl/KCl flux at a pressure of 30 kbar and temperature of 1350-1450
C using the cubic anvil high-pressure technique. The superconducting transition
temperature of the obtained single crystals varies between 45 and 53 K.Obtained
crystals are characterized by a full diamagnetic response in low magnetic
fields and by a high critical current density in high magnetic fields.
Structural refinement has been performed on single crystal. Differential
thermal analysis investigations at 1 bar Ar pressure show decomposition of
SmFeAsO1-xFy at 1302 C.Comment: 12 pages, 3 tables, 6 figure
Preliminary results of fast neutron treatments in carcinoma of the pancreas
A group of 30 patients with adenocarcinoma of the pancreas including some patients with very advanced disease, were treated with the so-called mixed beam modality employing photon treatments three times per week and neutron treatments twice a week. Two hundred Rads or equivalent Rads (RBE 3.3) were given in daily fractions aiming at a total dose of 6000 Rads in 6 to 8 weeks. The treatments were well tolerated and significant palliation was achieved in 26 to 30 cases. Twelve months survival was 33 percent with a median survival of 7 months or 210 days. Treatment techniques and localization procedures are discussed
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