1,493 research outputs found
Phenomenology of the normal state in-plane transport properties of high- cuprates
In this article, I review progress towards an understanding of the normal
state (in-plane) transport properties of high- cuprates in the light of
recent developments in both spectroscopic and transport measurement techniques.
Against a backdrop of mounting evidence for anisotropic single-particle
lifetimes in cuprate superconductors, new results have emerged that advocate
similar momentum dependence in the transport decay rate ({\bf k}). In
addition, enhancement of the energy scale (up to the bare bandwidth) over which
spectroscopic information on the quasiparticle response can be obtained has led
to the discovery of new, unforeseen features that surprisingly, may have a
significant bearing on the transport properties at the dc limit. With these two
key developments in mind, I consider here whether all the ingredients necessary
for a complete phenomenological description of the anomalous normal state
transport properties of high- cuprates are now in place.Comment: 31 pages, 10 figure
Assessment of Clinical Partner Violence Screening Tools
Objective: to compare the Women’s Experience with Battering Scale (WEB) with the Index of Spouse Abuse-Physical Scale (ISA-P) as screening tools to identify intimate partner violence (IPV).
Methods: We conducted a large cross-sectional survey of women age 18 to 65 attending one of two family practice clinics from 1997 to 1998. All women completed both the WEB and the ISA-P and a telephone interview. We figured agreement estimates between the two tools, used stratified analyses to evaluate attributes of those more likely to screen as battered or physically assaulted, and compared associations between the WEB and ISA-P and a range of mental and physical health indicators known to be associated with IPV.
Results: 18% of 1152 eligible women surveyed had experienced IPV in a current or most recent intimate rela-tionship with a male partner; 17% had been battered (WEB+), and 10% had been physically assaulted (ISA-P+). Had we used the ISA-P alone to assess IPV, we would have missed almost 45% of IPV. As anticipated, the ISA-P was more strongly associated with IPV-associated injuries and number of physician visits in the last year. The WEB was more strongly associated with self-perceived mental health, anxiety, depression, drug abuse, and low social support.
Conclusion: Clinicians need validated screening tools to rapidly and reliably screen patients for IPV. Most screening tools assess physical violence and injury without considering the more chronic experience of battering and the psychological terror associated with this violence. The WEB may identify more abused women than tools measuring physical assaults
Neutron interferometric measurement of the scattering length difference between the triplet and singlet states of n-He
We report a determination of the n-He scattering length difference
(
(statistical) (systematic)) fm between the triplet and singlet
states using a neutron interferometer. This revises our previous result (-5.610 (statistical) (systematic)
fm obtained using the same technique in 2008. This revision is due to a
re-analysis of the 2008 experiment that includes a more robust treatment of the
phase shift caused by magnetic field gradients near the He cell.
Furthermore, we more than doubled our original data set from 2008 by acquiring
six months of additional data in 2013. Both the new data set and a re-analysis
of the older data are in good agreement. Scattering lengths of low Z isotopes
are valued for use in few-body nuclear effective field theories, provide
important tests of modern nuclear potential models and in the case of He
aid in the interpretation of neutron scattering from quantum liquids. The
difference was determined by measuring the relative phase
shift between two incident neutron polarizations caused by the spin-dependent
interaction with a polarized He target. The target He gas was sealed
inside a small, flat windowed glass cell that was placed in one beam path of
the interferometer. The relaxation of He polarization was monitored
continuously with neutron transmission measurements. The neutron polarization
and spin flipper efficiency were determined separately using He analyzers
and two different polarimetry analysis methods. A summary of the measured
scattering lengths for n-He with a comparison to nucleon interaction models
is given
Field-induced quantum critical route to a Fermi liquid in high-temperature superconductors
In high transition temperature (T_c) superconductivity, charge doping is a
natural tuning parameter that takes copper oxides from the antiferromagnet to
the superconducting region. In the metallic state above T_c the standard
Landau's Fermi-liquid theory of metals as typified by the temperature squared
(T^2) dependence of resistivity appears to break down. Whether the origin of
the non-Fermi-liquid behavior is related to physics specific to the cuprates is
a fundamental question still under debate. We uncover a new transformation from
the non-Fermi- to a standard Fermi-liquid state driven not by doping but by
magnetic field in the overdoped high-T_c superconductor Tl_2Ba_2CuO_{6+x}. From
the c-axis resistivity measured up to 45 T, we show that the Fermi-liquid
features appear above a sufficiently high field which decreases linearly with
temperature and lands at a quantum critical point near the superconductivity's
upper critical field -- with the Fermi-liquid coefficient of the T^2 dependence
showing a power-law diverging behavior on the approach to the critical point.
This field-induced quantum criticality bears a striking resemblance to that in
quasi-two dimensional heavy-Fermion superconductors, suggesting a common
underlying spin-related physics in these superconductors with strong electron
correlations.Comment: 6 pages, 4 figure
The Relationship Between Diet, Activity, and Other Factors, and Postpartum Weight Change by Race
Objective: To identify the impact of dietary intake and activity level on postpartum weight change.
Methods: White (n = 121) and black (n = 224) women, 7-12 months postpartum, participating in the Special Supplemental Feeding Program for Women, Infants, and Children were assessed for dietary intake, activity level, body weight, and other maternal characteristics.
Results: For both black and white women, the most important variables in predicting postpartum weight loss were pre-pregnancy weight, gestational weight gain, parity, and prenatal exercise. After these factors were controlled, race predicted that black women retained 6.4 lb more than white women. These results may be due to the finding that black women reported significantly higher mean energy intake (2039 versus 1552 kcal, P \u3c .001), higher percent fat in diet (41 versus 38%, P \u3c .001), and significantly lower amounts of prenatal and postpartum activity.
Conclusion: Higher energy intake and lower activity levels in black postpartum mothers compared with white mothers may contribute to the significantly higher rates of obesity found in black mothers. This study suggests the need for intervention strategies in the prenatal and postpartum periods to help those at risk of retaining weight gained during pregnancy
Enhanced electron correlations in the new binary stannide PdSn4: a homologue of the Dirac nodal arc semimetal PtSn4
The advent of nodal-line semi-metals, i.e. systems in which the conduction
and valence bands cross each other along a closed trajectory (line or loop)
inside the Brillouin zone, has opened up a new arena for the exploration of
topological condensed matter in which, due to a vanishing density of states
near the Fermi level, electron correlation effects may also play an important
role. In spite of this conceptual richness however, material realization of
nodal-line (loop) fermions is rare, with PbTaSe2, ZrSiS and PtSn4 the only
promising known candidates. Here we report the synthesis and physical
properties of a new compound PdSn4 that is isostructural with PtSn4 yet
possesses quasiparticles with significantly enhanced effective masses. In
addition, PdSn4 displays an unusual polar angular magnetoresistance which at a
certain field orientation, varies linearly with field up to 55 Tesla. Our study
suggests that, in association with its homologue PtSn4 whose low-lying
excitations were recently claimed to possess Dirac node arcs, PdSn4 may be a
promising candidate in the search for novel topological states with enhanced
correlation effects.Comment: 6 figures, 1 tabl
Precision Measurement of the n-3He Incoherent Scattering Length Using Neutron Interferometry
We report the first measurement of the low-energy neutron-He incoherent
scattering length using neutron interferometry: fm. This is in good agreement with a
recent calculation using the AV18+3N potential. The neutron-He scattering
lengths are important for testing and developing nuclear potential models that
include three nucleon forces, effective field theories for few-body nuclear
systems, and neutron scattering measurements of quantum excitations in liquid
helium. This work demonstrates the first use of a polarized nuclear target in a
neutron interferometer.Comment: 4 figure
Absence of residual quasiparticle conductivity in the underdoped cuprate YBa2Cu4O8
We report here measurements of the in-plane thermal conductivity K(T) of the
underdoped cuprate YBa2Cu4O8 (Y124) below 1K. K(T) is shown to follow a simple,
phononic T^3 dependence at the lowest temperatures for both current directions,
with a negligible linear, quasiparticle contribution. This observation is in
marked contrast with behavior reported in optimally doped cuprates, and implies
that extended zero-energy (or low energy) low-energy quasiparticles are absent
in YBa2Cu4O8 at low temperatures.Comment: RevTex, 4 pages, 2 figures, Revised versio
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