374 research outputs found
Consistency of parity-violating pion-nucleon couplings extracted from measurements in 18F and 133Cs
The recent measurement of the nuclear anapole moment of 133Cs has been
interpreted to yield a value of the weak pion-nucleon coupling H_pi^1 which
contradicts the upper limit from the 18F experiments. We argue that because of
the sensitivity of the anapole moment to H_rho^0 in the odd proton nucleus
133Cs, there is a combination of weak meson-nucleon couplings which satisfies
both experiments and which is (barely) in agreement with theory. In addition,
the anapole moment measurement in 205Tl gives a constraint which is
inconsistent with the value from 133Cs, calling into question the theory of
nuclear anapole moments. We argue that measurements of directional asymmetry in
n+p-->d+gamma and in the photo-disintegration of the deuteron by circularly
polarized photons, combined with results from pp scattering, would determine
H_pi^1 and several other weak meson-nucleon couplings in a model-independent
way.Comment: 9 pages, RevTeX, 1 figure, eps, submitted to Phys. Rev.
Hawking radiation, Unruh radiation and the equivalence principle
We compare the response function of an Unruh-DeWitt detector for different
space-times and different vacua and show that there is a {\it detailed}
violation of the equivalence principle. In particular comparing the response of
an accelerating detector to a detector at rest in a Schwarzschild space-time we
find that both detectors register thermal radiation, but for a given,
equivalent acceleration the fixed detector in the Schwarzschild space-time
measures a higher temperature. This allows one to locally distinguish the two
cases. As one approaches the horizon the two temperatures have the same limit
so that the equivalence principle is restored at the horizon.Comment: 9 pages. Added references and added discussion. To be published in
PR
Supplemental instruction in the first intermediate accounting course: Investigation of an intervention strategy to improve student performance: Working paper series--11-13
The primary objective of this study is to assess the effectiveness of supplemental instruction (SI) on students' performance in the first intermediate accounting course. We perform analysis of covariance to evaluate the effect of SI attendance on course grades, after controlling for incoming grade point average, financial principles grade, and whether the principles course was taken at a university or community college. Additionally, we provide descriptive information regarding student characteristics and SI usage. Results indicate that SI participation had a significant effect on the first intermediate course grade, with an improvement in course GPA of .57 for students who attended three or more SI sessions. Additionally, results confirm that the above control factors were all important indicators of success in the course. While this study's results suggest SI is a successful intervention strategy, it was conducted at one institution. Consequently, generalization of the results may be limited to similar institutions of higher learning, particularly for institutions with different student demographics. Additional research at dissimilar institutions, as well comparing SI to alternative intervention strategies, would help institutions allocate scarce resources among the most effective programs. This study extends prior research on SI impact to an upper-division accounting course, as well as combining the SI research stream with research on grade determinants in the first intermediate accounting course. Using this information to identify students at risk may help improve the potential for their success if academic advisors and course instructors strongly encourage these students throughout the semester to participate in SI
Olfactory deficits in an alpha-synuclein fly model of Parkinson's disease
Parkinson's disease (PD) is the most common motor neurodegenerative disorder. Olfactory dysfunction is a prevalent feature of PD. It often precedes motor symptoms by several years and is used in assisting PD diagnosis. However, the cellular and molecular bases of olfactory dysfunction in PD are not known. The fruit fly Drosophila melanogaster, expressing human alpha-synuclein protein or its mutant, A30P, captures several hallmarks of PD and has been successfully used to model PD in numerous studies. First, we report olfactory deficits in fly expressing A30P (A30P), showing deficits in two out of three olfactory modalities, tested - olfactory acuity and odor discrimination. The remaining third modality is odor identification/naming. Second, oxidative stress is an important environmental risk factor of PD. We show that oxidative stress exacerbated the two affected olfactory modalities in younger A30P flies. Third, different olfactory receptor neurons are activated differentially by different odors in flies. In a separate experiment, we show that the odor discrimination deficit in A30P flies is general and not restricted to a specific class of chemical structure. Lastly, by restricting A30P expression to dopamine, serotonin or olfactory receptor neurons, we show that A30P expression in dopamine neurons is necessary for development of both acuity and discrimination deficits, while serotonin and olfactory receptor neurons appeared not involved. Our data demonstrate olfactory deficits in a synuclein fly PD model for exploring olfactory pathology and physiology, and for monitoring PD progression and treatment
Measurements at low energies of the polarization-transfer coefficient Kyy' for the reaction 3H(p,n)3He at 0 degrees
Measurements of the transverse polarization coefficient Kyy' for the reaction
3H(p,n)3He are reported for outgoing neutron energies of 1.94, 5.21, and 5.81
MeV. This reaction is important both as a source of polarized neutrons for
nuclear physics experiments, and as a test of theoretical descriptions of the
nuclear four-body system. Comparison is made to previous measurements,
confirming the 3H(p,n)3He reaction can be used as a polarized neutron source
with the polarization known to an accuracy of approximately 5%. Comparison to
R-matrix theory suggests that the sign of the 3F3 phase-shift parameter is
incorrect. Changing the sign of this parameter dramatically improves the
agreement between theory and experiment.Comment: 12 pages, RevTeX, 5 eps figures, submitted to Phys. Rev.
Performance evaluation of novel square-bordered position-sensitive silicon detectors with four-corner readout
We report on a recently developed novel type of large area (62 mm x 62 mm)
position sensitive silicon detector with four-corner readout. It consists of a
square-shaped ion-implanted resistive anode framed by additional
low-resistivity strips with resistances smaller than the anode surface
resistance by a factor of 2. The detector position linearity, position
resolution, and energy resolution were measured with alpha-particles and heavy
ions. In-beam experimental results reveal a position resolution below 1 mm
(FWHM) and a very good non-linearity of less than 1% (rms). The energy
resolution determined from 228Th alpha source measurements is around 2% (FWHM).Comment: 13 pages, 10 figures, submitted to Nucl. Instr. and Meth.
Perceptions of Academic Fieldwork Coordinators Regarding the Value of Fieldwork in Emerging Areas of Practice
This study investigated the perceptions of academic fieldwork coordinators (AFWCs) regarding emerging areas of practice as fieldwork experiences for entry-level occupational therapy (OT) students. Further, this study explored several aspects of fieldwork experiences in emerging areas of practice on student personal and professional development, academic curriculum, partnering community agencies, and the profession at large. A survey designed through Qualtrics®, an electronic survey system, was sent to 163 AFWCs of fully accredited master’s and doctoral entry-level OT programs. Forty-four participants (27%) completed the 16-question survey. Significance at p \u3c .05 was found in higher levels of Bloom’s taxonomy student performance when compared to traditional areas of practice. Common perceptions found among the AFWCs related to emerging areas of practice fieldwork experiences included: improved student professional and personal skills, increased connections and collaborations across and in health care disciplines, an enhanced ability to define and understand OT. Continued opportunities for fieldwork in emerging areas of practice are essential as the profession contemplates new markets and avenues in a changing health care environment
Neutron Beam Effects on Spin Exchange Polarized He-3
We have observed depolarization effects when high intensity cold neutron
beams are incident on alkali-metal-spin-exchange polarized He-3 cells used as
neutron spin filters. This was first observed as a reduction of the maximum
attainable He-3 polarization and was attributed to a decrease of alkali-metal
polarization, which led us to directly measure alkali-metal polarization and
spin relaxation over a range of neutron fluxes at LANSCE and ILL. The data
reveal a new alkali-metal spin-relaxation mechanism that approximately scales
as the square root of the neutron capture-flux density incident on the cell.
This is consistent with an effect proportional to the recombination-limited ion
concentration, but is much larger than expected from earlier work.Comment: submitted to Physical Review Letter
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