1,567 research outputs found
Segregation by thermal diffusion in granular shear flows
Segregation by thermal diffusion of an intruder immersed in a sheared
granular gas is analyzed from the (inelastic) Boltzmann equation. Segregation
is induced by the presence of a temperature gradient orthogonal to the shear
flow plane and parallel to gravity. We show that, like in analogous systems
without shear, the segregation criterion yields a transition between upwards
segregation and downwards segregation. The form of the phase diagrams is
illustrated in detail showing that they depend sensitively on the value of
gravity relative to the thermal gradient. Two specific situations are
considered: i) absence of gravity, and ii) homogeneous temperature. We find
that both mechanisms (upwards and downwards segregation) are stronger and more
clearly separated when compared with segregation criteria in systems without
shear.Comment: 8 figures. To appear in J. Stat. Mec
Phase diagram of the metal-insulator transition in 2D electronic systems
We investigated the interdependence of the effects of disorder and carrier
correlations on the metal-insulator transition in two-dimensional electronic
systems. We present a quantitative metal-insulator phase diagram. Depending on
the carrier density we find two different types of metal-insulator transition -
a continuous localization for rs=<8 and a discontinuous transition at higher
rs. The critical level of disorder at the transition decreases with decreasing
carrier density. At very low carrier densities we find that the system is
always insulating. The value of the conductivity at the transition is
consistent with recent experimental measurements. The self-consistent method
which we have developed includes the effects of both disorder and correlations
on the transition, using a density relaxation theory with the Coulomb
correlations determined from numerical simulation data.Comment: 4 pages, RevTeX + epsf, 5 figures. New comments on conducting phase
and on the conductivity. References updated and correcte
Estrogen Receptor Genotypes, Menopausal Status, and the Effects of Tamoxifen on Lipid Levels: Revised and Updated Results
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109960/1/cptclpt2010143.pd
Muon capture by 3He nuclei followed by proton and deuteron production
The paper describes an experiment aimed at studying muon capture by
nuclei in pure and mixtures at various densities. Energy distributions of
protons and deuterons produced via and are measured for the
energy intervals MeV and MeV, respectively. Muon capture
rates, and are obtained using two different analysis methods. The
least--squares methods gives , . The Bayes theorem
gives ,
. The experimental
differential capture rates, and , are compared with theoretical
calculations performed using the plane--wave impulse approximation (PWIA) with
the realistic NN interaction Bonn B potential. Extrapolation to the full energy
range yields total proton and deuteron capture rates in good agreement with
former results.Comment: 17 pages, 13 figures, accepted for publication in PR
Evaluation of pedometry as a patient-centered outcome in patients undergoing hematopoietic cell transplant (HCT): A comparison of pedometry and patient-reports of symptoms, health, and quality of life.
Aims We evaluated pedometry as a novel patient-centered outcome because it enables passive continuous assessment of activity and may provide information about the consequences of symptomatic toxicity complementary to self-report. Methods Adult patients undergoing hematopoietic cell transplant (HCT) wore pedometers and completed PRO assessments during transplant hospitalization (4 weeks) and 4 weeks post-discharge. Patient reports of symptomatic treatment toxicities (single items from PROCTCAE, http://healthcaredelivery.cancer.gov/pro-ctcae) and symptoms, physical health, mental health, and quality of life (PROMIS Global-10, http://nih.promis.org), assessed weekly with 7-day recall on Likert scales, were compared individually with pedometry data, summarized as average daily steps per week, using linear mixed models. Results Thirty-two patients [mean age 55 (SD = 14), 63 % male, 84 % white, 56 % autologous, 43 % allogeneic] completed a mean 4.6 (SD = 1.5, range 1–8) evaluable assessments. Regression model coefficients (β) indicated within-person decrements in average daily steps were associated with increases in pain (β = -852; 852 fewer steps per unit increase in pain score, p<0.001), fatigue (β = -886, p<0.001), vomiting (β = -518, p<0.01), shaking/chills (β = -587, p<0.01), diarrhea (β = -719, p<0.001), shortness of breath (β = -1018, p<0.05), reduction in carrying out social activities (β = 705, p<0.01) or physical activities (β = 618, p<0.01), and global physical health (β = 101, p<0.001), but not global mental health or quality of life. Conclusions In this small sample of HCT recipients, more severe symptoms, impaired physical health, and restrictions in the performance of usual daily activities were associated with statistically significant decrements in objectively measured daily steps. Pedometry may be a valuable outcome measure and validation anchor in clinical research
Photofission of heavy nuclei at energies up to 4 GeV
Total photofission cross sections for 238U, 235U, 233U, 237Np, 232Th, and
natPb have been measured simultaneously, using tagged photons in the energy
range Egamma=0.17-3.84 GeV. This was the first experiment performed using the
Photon Tagging Facility in Hall B at Jefferson Lab. Our results show that the
photofission cross section for 238U relative to that for 237Np is about 80%,
implying the presence of important processes that compete with fission. We also
observe that the relative photofission cross sections do not depend strongly on
the incident photon energy over this entire energy range. If we assume that for
237Np the photofission probability is equal to unity, we observe a significant
shadowing effect starting below 1.5 GeV.Comment: 4 pages of RevTex, 6 postscript figures, Submitted to Phys. Rev. Let
Pilot randomized trial of an electronic symptom monitoring and reporting intervention for hospitalized adults undergoing hematopoietic stem cell transplantation
Purpose: Patients undergoing a hematopoietic stem cell transplantation (HCT) have varied symptoms during their hospitalization. This study examined whether daily symptom reporting (with electronic patient-reported outcomes [PROs]) in an inpatient bone marrow transplant clinic reduced symptom burden on post-transplant days +7, +10, and +14. Methods: A prospective, single-institution1:1 pilot randomized, two-arm study recruited HCT patients. HCT inpatients (N=76) reported daily on 16 common symptoms using the PRO version of the Common Terminology for Adverse Events (PRO-CTCAE). Fisher’s exact test was used to examine differences in the proportion of patients reporting individual symptoms. Multivariable linear regression modeling was used to examine group differences in peak symptom burden, while controlling for symptom burden at baseline, age, comorbidity, and transplantation type (autologous or allogeneic). Results: HCT patients receiving the PRO intervention also experienced lower peak symptom burden (average of 16 symptoms) at days +7, +10, and +14 (10.4 vs 14.5, p =0.03). Conclusions: Daily use of electronic symptom reporting to nurses in an inpatient bone marrow transplant clinic reduced peak symptom burden and improved individual symptoms during the two weeks post-transplant. A multi-site site trial is warranted to demonstrate the generalizability, efficacy, and value of this intervention
Bayesian approach to cyclic activity of CF Oct
Bayesian statistical methods of Gregory-Loredo and the Bretthorst
generalization of the Lomb-Scargle periodogram have been applied for studying
activity cycles of the early K-type subgiant star CF Oct. We have used a ~45
year long dataset derived from archival photographic observations, published
photoelectric photometry, Hipparcos data series and All Sky Automated Survey
archive. We have confirmed the already known rotational period for the star of
20.16 d and have shown evidences that it has exhibited changes from 19.90 d to
20.45 d. This is an indication for stellar surface differential rotation.The
Bayesian magnitude and time--residual analysis reveals clearly at least one
long-term cycle. The cycle lenght's posterior distributions appear to be
multimodal with a pronounced peak at a period of 7.1 y with FWHM of 54 d for
time-residuals and at a period of 9.8 y with FWHM of 184 d for magitude data.
These results are consistent with the previously postulated cycle of 9+/-3
years.Comment: The paper contains 6 figures and 3 tables. Accepted for publication
in Monthly Notices of the Royal Astronomical Society Main Journa
Time resolution of the plastic scintillator strips with matrix photomultiplier readout for J-PET tomograph
Recent tests of a single module of the Jagiellonian Positron Emission
Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips
have proven its applicability for the detection of annihilation quanta (0.511
MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved
resolution is almost by a factor of two better with respect to the current
TOF-PET detectors and it can still be improved since, as it is shown in this
article, the intrinsic limit of time resolution for the determination of time
of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much
lower. As the major point of the article, a method allowing to record
timestamps of several photons, at two ends of the scintillator strip, by means
of matrix of silicon photomultipliers (SiPM) is introduced. As a result of
simulations, conducted with the number of SiPM varying from 4 to 42, it is
shown that the improvement of timing resolution saturates with the growing
number of photomultipliers, and that the 2 x 5 configuration at two ends
allowing to read twenty timestamps, constitutes an optimal solution. The
conducted simulations accounted for the emission time distribution, photon
transport and absorption inside the scintillator, as well as quantum efficiency
and transit time spread of photosensors, and were checked based on the
experimental results. Application of the 2 x 5 matrix of SiPM allows for
achieving the coincidence resolving time in positron emission tomography of
0.170 ns for 15 cm axial field-of-view (AFOV) and 0.365 ns
for 100 cm AFOV. The results open perspectives for construction of a
cost-effective TOF-PET scanner with significantly better TOF resolution and
larger AFOV with respect to the current TOF-PET modalities.Comment: To be published in Phys. Med. Biol. (26 pages, 17 figures
Q^2 Dependence of the S_{11}(1535) Photocoupling and Evidence for a P-wave resonance in eta electroproduction
New cross sections for the reaction are reported for total
center of mass energy =1.5--2.3 GeV and invariant squared momentum transfer
=0.13--3.3 GeV. This large kinematic range allows extraction of new
information about response functions, photocouplings, and coupling
strengths of baryon resonances. A sharp structure is seen at 1.7 GeV.
The shape of the differential cross section is indicative of the presence of a
-wave resonance that persists to high . Improved values are derived for
the photon coupling amplitude for the (1535) resonance. The new data
greatly expands the range covered and an interpretation of all data with
a consistent parameterization is provided.Comment: 31 pages, 9 figure
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