4,248 research outputs found
Standard interest profiles - Development of technical subjects Final report
NASA university program for technology transfer, and development of Standard Interest Profiles /SIP
Interference Effects, Time Reversal Violation and Search for New Physics in Hadronic Weak Decays
We propose some methods for studying hadronic sequential two-body decays
involving more spinning particles. It relies on the analysis of T-odd and
T-even asymmetries, which are related to interference terms. The latter
asymmetries turn out to be as useful as the former ones in inferring time
reversal violating observables; these in turn may be sensitive, under some
particular conditions, to possible contributions beyond the standard model. Our
main result is that one can extract such observables even after integrating the
differential decay width over almost all of the available angles. Moreover we
find that the correlations based exclusively on momenta are quite general,
since they provide as much information as those involving one or more spins. We
generalize some methods already proposed in the literature for particular decay
channels, but we also pick out a new kind of time reversal violating
observables. Our analysis could be applied, for example, to data of LHCb
experiment.Comment: 35 page
A Learner-Centered Diabetes Management Curriculum
OBJECTIVE Diabetes errors, particularly insulin administration errors, can lead to complications and death in the pediatric inpatient setting. Despite a lecture-format curriculum on diabetes management at our children’s hospital, resident diabetes-related errors persisted. We hypothesized that a multifaceted, learner-centered diabetes curriculum would help reduce pathway errors. RESEARCH DESIGN AND METHODS The 8-week curricular intervention consisted of 1) an online tutorial addressing residents’ baseline diabetes management knowledge, 2) an interactive diabetes pathway discussion, 3) a learner-initiated diabetes question and answer session, and 4) a case presentation featuring embedded pathway errors for residents to recognize, resolve, and prevent. Errors in the 9 months before the intervention, as identified through an incident reporting system, were compared with those in the 10 months afterward, with errors classified as relating to insulin, communication, intravenous fluids, nutrition, and discharge delay. RESULTS Before the curricular intervention, resident errors occurred in 28 patients (19.4% of 144 diabetes admissions) over 9 months. After the intervention, resident errors occurred in 11 patients (6.6% of 166 diabetes admissions) over 10 months, representing a statistically significant (P = 0.0007) decrease in patients with errors from before intervention to after intervention. Throughout the study, the errors were distributed into the categories as follows: insulin, 43.8%; communication, 39.6%; intravenous fluids, 14.6%; nutrition, 0%; and discharge delay, 2.1%. CONCLUSIONS An interactive learner-centered diabetes curriculum for pediatric residents can be effective in reducing inpatient diabetes errors in a tertiary children’s hospital. This educational model promoting proactive learning has implications for decreasing errors across other medical disciplines
Effects of atomic diffraction on the Collective Atomic Recoil Laser
We formulate a wave atom optics theory of the Collective Atomic Recoil Laser,
where the atomic center-of-mass motion is treated quantum mechanically. By
comparing the predictions of this theory with those of the ray atom optics
theory, which treats the center-of-mass motion classically, we show that for
the case of a far off-resonant pump laser the ray optics model fails to predict
the linear response of the CARL when the temperature is of the order of the
recoil temperature or less. This is due to the fact that in theis temperature
regime one can no longer ignore the effects of matter-wave diffraction on the
atomic center-of-mass motion.Comment: plain tex, 10 pages, 10 figure
Partially Absorbed Comptonization Spectrum from the Nearly Edge-on Source X 1822-371
We report the results of a spectral analysis over the range 0.1-200 keV
performed on the dipping source X 1822-371 observed by BeppoSAX. We find the
best fit to the continuum using a partially covered Comptonization model, due
to scattering off soft seed photons by electrons at a temperature of ~4.8 keV,
without the presence of any soft blackbody emission. The equivalent hydrogen
column obtained for the absorbed component is ~4.5 10^{22} cm^{-2}, an order of
magnitude larger than the Galactic absorption for this source, and the covering
fraction is ~71%. Because the inclination angle of X 1822-371 to the line of
sight is ~85^\circ, this model gives a reasonable scenario for the source: the
Comptonized spectrum could come from an extended accretion disk corona (ADC),
probably the only region that can be directly observed due to the high
inclination. The excess of matter producing the partial covering could be close
to the equatorial plane of the system, above the outer disk, occulting the
emission from the inner disk and the inner part of the ADC. An iron emission
line is also present at ~6.5 keV with an equivalent width of ~150 eV. We argue
that this strong iron line cannot be explained as reflection of the Comptonized
spectrum by the accretion disk. It is probably produced in the ADC. An emission
line at ~1.9 keV (with an equivalent width of ~54 eV) and an absorption edge at
\~8.7 keV (with an optical depth of ~0.1) are also required to fit this
spectrum. These features are probably produced by highly ionized iron (Fe XXIV)
present in the outer part of the ADC, where the plasma density is
\~10^{11}-10^{12} cm^{-3} and ionized plasma is present.Comment: 15 pages, including 3 figures. Accepted by ApJ. Corrected typos and
Figure
Study of the Cir X--1 Broad Band Spectrum at Orbital Phases Close to the Apoastron
We report on the results of a BeppoSAX (1.8--200 keV) observation of the
peculiar X-ray binary source Circinus X--1 (Cir X--1) at the orbital phases
between 0.61 and 0.63. We find that three components are needed to fit the
broad band spectrum: a blackbody component, at a temperature of keV,
a Comptonized component, with a seed-photon temperature of keV,
electron temperature of keV and optical depth of , and a
power-law component dominating the spectrum at energies higher than 20 keV. We
interpret the blackbody as the emission from the accretion disk, while the
Comptonized component probably comes from a corona surrounding the inner part
of the system. This spectrum is different from that observed at the periastron
(Iaria et al. 2001a) because of the presence of the blackbody component. We
discuss the implications of this difference and the presence of the power-law
component.Comment: 15 pages, 6 figures, accepted by Ap
Spectral Evolution of Circinus X-1 Along its Orbit
We report on the spectral analysis of Circinus X-1 observed by the ASCA
satellite in March 1998 along one orbital period. The luminosity of the source
(in the 0.1-100 keV band) ranges from erg s at the
periastron (orbital phase 0.01) to erg s at orbital
phase 0.3. From the spectral analysis and the lightcurve we argue that Cir X-1
shows three states along the orbital evolution. The first state is at the
orbital phase interval 0.97-0.3: the luminosity becames super-Eddington and a
strong flaring activity is present. In this state a shock could form in the
inner region of the system due to the super-Eddington accretion rate, producing
an outflow of ionized matter whose observational signature could be the
prominent absorption edge at keV observed in the energy spectrum at
these phases. In the second state, corresponding to the orbital phase interval
between 0.3 and 0.7, the accretion rate is sub-Eddington and we observe a
weaker outflow, with smaller hydrogen column: the absorption edge is now at
keV with an optical depth a factor of 2.5 to 6 smaller. The third
state corresponds to the orbital phase interval 0.78-0.97. In this state the
best fit model to the spectrum requires the presence of a partial covering
component, indicating that the emission from the compact object is partially
absorbed by neutral matter, probably the atmosphere of the companion star
and/or the accreting matter from the companion.Comment: 18 pages, 3 figures. Accepted by Ap
Properties of Regge Trajectories
Early Chew-Frautschi plots show that meson and baryon Regge trajectoies are
approximately linear and non-intersecting. In this paper, we reconstruct all
Regge trajectories from the most recent data. Our plots show that meson
trajectories are non-linear and intersecting. We also show that all current
meson Regge trajectories models are ruled out by data.Comment: 30 pages, latex, 18 figures, to be published in Physical Review
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