271 research outputs found
Increased Sensitivity to Physical Activity in Healthy Older Adults Predicts Worse Pain and Functional Outcomes
poster abstractPrior research indicates older adults with knee osteoarthritis (OA) have increased
sensitivity to physical activity (SPA) and respond to physical activities of stable intensity
with increases in pain. SPA predicted self-reported pain and function in older adults with
knee OA. It is unknown whether SPA is present in healthy older adults without chronic
pain and predicts functional outcomes. The purpose of this study was to determine if
SPA in response to a standardized 6-minute Walk Test cross-sectionally predicted selfreported pain, physical function, and physical activity behaviors in healthy older adults.
Forty-two older adults (age=67.5±5 years) completed the Pain subscale of the Quality of
Well Being scale (QWB–measures the frequency and severity of pain during common
daily activities), the Short Form Health Survey (SF-36–measure of physical function),
the 6-Minute Walk Test (6MWT), and wore an accelerometer on the hip for 7 days.
Subjects rated overall bodily discomfort (0-100 scale) prior to and during each minute of
the 6MWT. RPE was recorded at the end of the walk. An SPA index was created by
subtracting the initial bodily discomfort ratings from the peak ratings. Average moderate
to vigorous physical activity/day (MVPA) and steps/day were recorded from the
accelerometer. Dependent variables were analyzed with hierarchical linear regressions
with SPA as the final predictor. Sixty percent of older adults experienced SPA
(SPA=9.5±15.6). After accounting for age, sex, BMI, and meters walked on the 6MWT,
SPA significantly predicted steps and MVPA per day, RPE on the 6MWT, and severity
and frequency of activity related pain on the QWB scale. These results revealed that
increased SPA in healthy older adults was associated with fewer steps and MVPA per
day, greater exertion on 6MWT, and greater self-reported activity-related pain. This
study was funded by the IUPUI School of PETM Faculty Research Opportunity Grant
Torque magnetometry studies of new low temperature metamagnetic states in ErNi_{2}B_{2}C
The metamagnetic transitions in single-crystal ErNiBC have been
studied at 1.9 K with a Quantum Design torque magnetometer. The critical fields
of the transitions depend crucially on the angle between applied field and the
easy axis [100]. Torque measurements have been made while changing angular
direction of the magnetic field (parallel to basal tetragonal -planes) in a
wide angular range (more than two quadrants). Sequences of metamagnetic
transitions with increasing field are found to be different for the magnetic
field along (or close enough to) the easy [100] axis from that near the hard
[110] axis. The study have revealed new metamagnetic states in ErNiBC
which were not apparent in previous longitudinal-magnetization and neutron
studies.Comment: 3 pages (4 figs. incl.) reported at 52th Magnetism and Magnetic
Materials Conference, Tampa, Florida, USA, November 200
Influence of high-energy electron irradiation on the transport properties of La_{1-x}Ca_{x}MnO_{3} films (x \approx 1/3)
The effect of crystal lattice disorder on the conductivity and colossal
magnetoresistance in La_{1-x}Ca_{x}MnO_{3} (x \approx 0.33) films has been
examined. The lattice defects are introduced by irradiating the film with
high-energy (\simeq 6 MeV) electrons with a maximal fluence of about 2\times
10^{17} cm^{-2}. This comparatively low dose of irradiation produces rather
small radiation damage in the films. The number of displacements per atom (dpa)
in the irradiated sample is about 10^{-5}. Nethertheless, this results in an
appreciable increase in the film resistivity. The percentage of resistivity
increase in the ferromagnetic metallic state (below the Curie tempetature
T_{c}) was much greater than that observed in the insulating state (above
T_{c}). At the same time irradiation has much less effect on T_{c} or on the
magnitude of the colossal magnetoresistance. A possible explanation of such
behavior is proposed.Comment: RevTex, 22 pages, 3 Postscript figures, submitted to Eur. Phys. J.
Torque magnetometry study of metamagnetic transitions in single-crystal HoNi2B2C at T\approx 1.9 K
Metamagnetic transitions in single-crystal rare-earth nickel borocarbide
HoNiBC have been studied at T\approx 1.9 K with a Quantum Design torque
magnetometer. This compound is highly anisotropic with a variety of
metamagnetic states at low temperature which includes antiferromagnetic,
ferrimagnetic, non-collinear and ferromagnetic-like (saturated paramagnet)
states. The critical fields of the transitions depend crucially on the angle
between applied field and the easy axis [110]. Measurements of torque
along the c-axis have been made while changing the angular direction of the
magnetic field (parallel to basal tetragonal -planes) and with changing
field at fixed angle over a wide angular range. Two new phase boundaries in the
region of the non-collinear phase have been observed, and the direction of the
magnetization in this phase has been precisely determined. At low field the
antiferromagnetic phase is observed to be multidomain. In the angular range
very close to the hard axis [100] (, where is the angle between field and the hard axis) the
magnetic behavior is found to be ``frustrated'' with a mixture of phases with
different directions of the magnetization.Comment: submitted to Phys. Rev. B, 12 pages, 12 figure
Investigation of the superconducting energy gap in the compound LuNiBC by the method of point contact spectroscopy: two-gap approximation
It is shown that the two-gap approximation is applicable for describing the
spectra of LuNiBC-Ag point contacts in a wide interval
of temperatures. The values and the temperature dependences of the large and
the small gaps in the plane and in the direction were estimated using
the generalized BTK model and the equations of Beloborodko. In the BCS
extrapolation the critical temperature of the small gap is 10 in the
plane and 14.5 in the direction. The absolute values of the gaps are
and . For the large gaps the
critical temperature coincides with the bulk , , and
their absolute values are very close, being about 3 in both orientations.
In the direction the contributions to the conductivity from the small and
the large gaps remain practically identical up to . In the
plane the contribution from the small gap is much smaller and decreases rapidly
as a temperature rises.Comment: 10 pages, 10 figures, submitted to Fiz. Nizk. Temp. (Low Temp. Phys.
Transport, thermal and magnetic properties of RuSr_2(Gd_{1.5}Ce_{0.5})Cu_2O_{10-\delta}, a magnetic superconductor
Resistivity, thermoelectric power, heat capacity and magnetization for
samples of RuSr_2(Gd_{1.5}Ce_{0.5})Cu_{2}O_{10-\delta} were investigated in the
temperature range 1.8-300 K with a magnetic field up to 8 T. The resistive
transitions to the superconducting state are found to be determined by the
inhomogeneous (granular) structure, characterized by the intragranular, T_{c0},
and intergranular, T_{cg}, transition temperatures. Heat capacity, C(T), shows
a jump at the superconducting transition temperature T_{c0}\approx 37.5 K. A
Schottky-like anomaly is found in C(T) below 20 K. This low temperature anomaly
can be attributed to splitting of the ground term of paramagnetic
Gd^{3+} ions by internal and external magnetic fields.Comment: 3 pages (4 figs. incl.), reported at 50th Magnetism and Magnetic
Materials Conference, San Jose, CA, USA, 200
Torque magnetometry studies of metamagnetic transitions in single-crystal HoNi_{2}B_{2}C and ErNi_{2}B_{2}C at T\approx 1.9 K
The metamagnetic transitions in single-crystal rare-earth nickel borocarbide
HoNi_{2}B_{2}C and ErNi_{2}B_{2}C have been studied at 1.9 K with a Quantum
Design torque magnetometer. The critical fields of the transitions depend
crucially on the angle between applied field and the easy axis [110] for
HoNi_2B_2C and [100] for ErNi_2B_2C. Torque measurements have been made while
changing angular direction of the magnetic field (parallel to basal tetragonal
ab-planes) in a wide angular range (more than two quadrants). The results are
used not only to check and refine the angular diagram for metamagnetic
transitions in these compounnds, but also to find new features of the
metamagnetic states. Among new results for the Ho borocarbide are the influence
of a multidomain antiferromagnetic state, and ``frustrated'' behavior of the
magnetic system for field directions close to the hard axis [100]. Torque
measurements of the Er borocarbide clearly show that the sequence of
metamagnetic transitions with increasing field (and the corresponding number of
metamagnetic states) depends on the angular direction of the magnetic field
relative to the easy axis.Comment: 3pages (4 figs. incl.) reported at 50th Magnetism and Magnetic
Materials Conference, San Jose, CA, USA, 200
Low-temperature metamagnetic states in single crystal TbNi2B2C studied by torque magnetometry
Metamagnetic transitions in single crystalTbNi2B2C have been studied at 1.9 K with a Quantum Design torque magnetometer. The critical fields for the transitions depend strongly on the angle between the applied field and the easy axis [100]. Torque measurements have been made while changing the angular direction of the magnetic field (parallel to basal tetragonal ab-planes) at fixed field magnitude and while changing the field magnitude at fixed angular direction over a wide angular range (more than two quadrants). Torque magnetometry (sensitive only to the component of magnetization perpendicular to the field) indicates not only a different sequence of metamagnetic phases for fields near the easy axis from those near the hard axis, but also the different natures of a principal metamagnetic phase near the hard axis. Comparison of the results with longitudinal magnetization measurements is presented
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