2,169 research outputs found
Charitable Giving Report: How Nonprofit Fundraising Performed in 2013
The Charitable Giving Report, derived from The Blackbaud Index, includes overall giving data from 4,129 nonprofit organizations representing 1.7 billion in online fundraising from 2013. This year's report features the addition of overall charitable giving data from 985 organizations and online giving data from 778 organizations
Susceptibility inhomogeneity and non-Fermi liquid behavior in UCu_{5-x}Pt_x
Transverse-field muSR shifts and relaxation rates have been measured in the
non-Fermi liquid (NFL) alloy system UCu_{5-x}Pt_x, x = 1.0, 1.5, and 2.5. At
low temperatures the fractional spread in Knight shifts delta K/K approx
deltachi/chi is gtrsim 2 for x = 1, but is only half this value for x = 1.5 and
2.5. In a disorder-driven scenario where the NFL behavior is due to a broadly
distributed (Kondo or Griffiths-phase cluster) characteristic energy E, our
results indicate that delta E/E_{rm av} approx (delta K/K)_{T=0} is similar for
UCu_{5-x}Pd_x (x = 1 and 1.5) and UCu_4Pt, but is reduced for UCu_{5-x}Pt_x, x
= 1.5 and 2.5. This reduction is due to a marked increase of E with increasing
x; the spread delta E is found to be roughly independent of x. Our results
correlate with the observed suppression of other NFL anomalies for x > 1 in
UCu_{5-x}Pt_x but not in UCu_{5-x}Pd_x, and are further evidence for the
importance of disorder in the NFL behavior of both these alloy systems.Comment: 4 pages, 2 figures, submitted to 10th International Conference on
Muon Spin Rotation, Relaxation, and Resonance, Oxford, UK, August 200
Effect of annealing on glassy dynamics and non-Fermi liquid behavior in UCu_4Pd
Longitudinal-field muon spin relaxation (LF-muSR) experiments have been
performed in unannealed and annealed samples of the heavy-fermion compound
UCu_4Pd to study the effect of disorder on non-Fermi liquid behavior in this
material. The muon spin relaxation functions G(t,H) obey the time-field scaling
relation G(t,H) = G(t/H^gamma) previously observed in this compound. The
observed scaling exponent gamma = 0.3 pm 0.1, independent of annealing. Fits of
the stretched-exponential relaxation function G(t) = exp[-(Lambda t)^K] to the
data yielded stretching exponentials K < 1 for all samples. Annealed samples
exhibited a reduction of the relaxation rate at low temperatures, indicating
that annealing shifts fluctuation noise power to higher frequencies. There was
no tendency of the inhomogeneous spread in rates to decrease with annealing,
which modifies but does not eliminate the glassy spin dynamics reported
previously in this compound. The correlation with residual resistivity
previously observed for a number of NFL heavy-electron materials is also found
in the present work.Comment: 4 pages, 3 figures, submitted to 10th International Conference on
Muon Spin Rotation, Relaxation, and Resonance, Oxford, UK, August 200
Glassy Spin Dynamics in Non-Fermi-Liquid UCu_{5-x}Pd_x, x = 1.0 and 1.5
Local f-electron spin dynamics in the non-Fermi-liquid heavy-fermion alloys
UCu_{5-x}Pd_x, x = 1.0 and 1.5, have been studied using muon spin-lattice
relaxation. The sample-averaged asymmetry function Gbar(t) indicates strongly
inhomogeneous spin fluctuations, and exhibits the scaling Gbar(t,H) =
Gbar(t/H^\gamma) expected from glassy dynamics. At 0.05 K \gamma(x=1.0) = 0.35
\pm 0.1, but \gamma(x=1.5) = 0.7 \pm 0.1. This is in contrast to inelastic
neutron scattering results, which yield \gamma = 0.33 for both concentrations.
There is no sign of static magnetism \gtrsim 10^{-3} \mu_B/U ion in either
material above 0.05 K. Our results strongy suggest that both alloys are quantum
spin glasses.Comment: 4 pages, 4 figures, to be published in Physical Review Letter
Preparing Students for Success on Examinations: Readiness Assurance Tests in a Graduate-Level Statistics Course
Formative feedback is one way to foster students' readiness for statistics examinations.
The use of Readiness Assurance Tests was examined as an educational intervention in which feedback was provided for both correct and incorrect responses in a graduate-level statistics course. Examination scores in the intervention group ( n = 56) were compared with those in a control group ( n = 42).
Intervention group examination scores significantly improved from 75.92 ± 14.52 on the Readiness Assurance Test to 90.06 ± 7.06, p < .001, on the midterm, and final examination scores improved from 78.23 ± 17.29 to 85.6 ± 6.98, p = .002. Intervention group midterm scores were significantly higher than those of the control group (90.06 ± 7.06 versus 79.7 ± 11.6, p < .001); however, no differences were found between the groups on the final examination (85.35 ± 9.46 versus 85.6 ± 6.98, p = .91).
Use of Readiness Assurance Tests was an effective modality to increase student self-efficacy, learning experience, and, relative to a control group, midterm examination performance in statistic
The Effect of Intermittent Normobaric Hyperoxia on Stem Cell Mobilization and Cytokine Expression
Charitable Giving Report: How Nonprofit Fundraising Performed in 2012
This report provides the largest analysis of overall and online giving trends in the nonprofit sector. Its aim is to provide a benchmark for giving and help inform nonprofits' fundraising strategies in 2013. Provides data on giving by sector and month, and outlines strategies that fundraisers are using in various sectors
Susceptibility Inhomogeneity and Non-Fermi-Liquid Behavior in Ce(Ru_{0.5}Rh_{0.5})_2Si_2
Magnetic susceptibility and muon spin rotation (\muSR) experiments have been
carried out to study the effect of structural disorder on the non-Fermi-liquid
(NFL) behavior of the heavy-fermion alloy Ce(Ru_{0.5}Rh_{0.5})_2Si_2. Analysis
of the bulk susceptibility in the framework of disorder-driven Griffiths-phase
and Kondo-disorder models for NFL behavior yields relatively narrow
distributions of characteristic spin fluctuation energies, in agreement with
\muSR linewidths that give the inhomogeneous spread in susceptibility. \muSR
and NMR data both indicate that disorder explains the "nearly NFL" behavior
observed above \sim2 K, but does not dominate the NFL physics found at low
temperatures and low magnetic fields.Comment: 6 pages, 4 figures, REVTeX, submitted to Phys. Rev.
Superconductivity of the Ternary Boride Li_2Pd_3B Probed by ^{11}B NMR
We report a ^{11}B NMR measurement on the recently discovered superconductor
Li_2Pd_3B. The nuclear spin lattice relaxation rate 1/T_1 shows a well-defined
coherence peak just below T_c (H=1.46 T)=5.7 K, and the spin susceptibility
measured by the Knight shift also decreases below T_c. These results indicate
that the superconductivity is of conventional nature, with an isotropic gap.
Our results also suggest that the -electrons of boron and the d-electrons of
palladium that hybridize with boron -electrons are primarily responsible for
the superconductivity.Comment: 4 pages, 5 figure
Spin dynamics in a structurally ordered non-Fermi liquid compound: YbRh_2Si_2
Muon spin relaxation (muSR) experiments have been carried out at low
temperatures in the non-Fermi-liquid heavy-fermion compound YbRh_2Si_2. The
longitudinal-field muSR relaxation function is exponential, indicative that the
dynamic spin fluctuations are homogeneous. The relaxation rate 1/T_1 varies
with applied field as H^{-y}, y = 1.0 \pm 0.1, which implies a scaling law of
the form \chi''(\omega) \propto \omega^{-y} f(\omega/T), \lim_{x\to0} f(x) = x
for the dynamic spin susceptibility.Comment: 5 pages, 2 figures. To be published in proceedings of musr2002
(Physica B
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