431 research outputs found
Weak dipole moment of in collisions with longitudinally polarized electrons
It is pointed out that certain CP-odd momentum correlations in the production
and subsequent decay of tau pairs in collisions get enhanced when the
is longitudinally polarized. Analytic expressions for these correlations
are obtained for the single-pion decay mode of when have
a ``weak" dipole form factor (WDFF) coupling to . For collisions
at the peak, a sensitivity of about 1-5\mbox{ cm} for
the WDFF can be reached using a {\em single} decay
channel, with 's likely to be available at the SLC at Stanford with
polarization of 62\%-75\%.Comment: 9 pages, Latex, PRL-TH-93/17 (Revised
Dietary protein intake and kidney function decline after myocardial infarction:the Alpha Omega Cohort
BACKGROUND: Post-myocardial infarction (MI) patients have a doubled rate of kidney function decline compared with the general population. We investigated the extent to which high intake of total, animal and plant protein are risk factors for accelerated kidney function decline in older stable post-MI patients. METHODS: We analysed 2255 post-MI patients (aged 60-80âyears, 80% men) of the Alpha Omega Cohort. Dietary data were collected with a biomarker-validated 203-item food frequency questionnaire. At baseline and 41âmonths, we estimated glomerular filtration rate based on the Chronic Kidney Disease Epidemiology Collaboration equations for serum cystatin C [estimated glomerular filtration rate (eGFRcysC)] alone and both creatinine and cystatin C (eGFRcr-cysC). RESULTS: Mean [standard deviation (SD)] baseline eGFRcysC and eGFRcr-cysC were 82 (20) and 79 (19) mL/min/1.73 m2. Of all patients, 16% were current smokers and 19% had diabetes. Mean (SD) total protein intake was 71 (19) g/day, of which two-thirds was animal and one-third plant protein. After multivariable adjustment, including age, sex, total energy intake, smoking, diabetes, systolic blood pressure, renin-angiotensin system blocking drugs and fat intake, each incremental total daily protein intake of 0.1âg/kg ideal body weight was associated with an additional annual eGFRcysC decline of -0.12 (95% confidence interval -0.19 to -0.04) mL/min/1.73 m2, and was similar for animal and plant protein. Patients with a daily total protein intake of â„1.20 compared with <0.80âg/kg ideal body weight had a 2-fold faster annual eGFRcysC decline of -1.60 versus -0.84âmL/min/1.73 m2. Taking eGFRcr-cysC as outcome showed similar results. Strong linear associations were confirmed by restricted cubic spline analyses. CONCLUSION: A higher protein intake was significantly associated with a more rapid kidney function decline in post-MI patients.</p
Measurement of the electric dipole moment using longitudinal polarization of beams
Certain CP-odd momentum correlations in the production and subsequent decay
of pairs in collisions are enhanced significantly when the
and beams are longitudinally polarized. These may be used to probe
the real and imaginary parts of , the electric dipole moment of
the . Closed-form expressions for these ``vector correlations'' and the
standard deviation of the operators defining them due to standard model
interactions are presented for the two-body final states of decays. If
42\% average polarization of each beam is achieved, as proposed for the
tau-charm factories, with equal integrated luminosities for each sign of
polarization and a total yield of pairs, it is
possible to attain sensitivities for of , , cm respectively and for of , , cm respectively at the three operating center-of-mass energies of
3.67, 4.25 and 10.58 GeV. These bounds emerge when the effects of a posible
weak dipole form factor are negligible as is the case when it is of
the same order of magnitude as . Furthermore, in such a
polarization experiment where different polarizations are possible, a
model-independent disentangling of their individual effects is possible, and a
technique to achieve this is described. A strong longitudinal polarization
physics programme at the tau-charm factory appears warranted.Comment: 30 pages, latex, no figure
Climatology of Mid-latitude Ionospheric Disturbances from the Very Large Array Low-frequency Sky Survey
The results of a climatological study of ionospheric disturbances derived
from observations of cosmic sources from the Very Large Array (VLA)
Low-frequency Sky Survey (VLSS) are presented. We have used the ionospheric
corrections applied to the 74 MHz interferometric data within the VLSS imaging
process to obtain fluctuation spectra for the total electron content (TEC)
gradient on spatial scales from a few to hundreds of kilometers and temporal
scales from less than one minute to nearly an hour. The observations sample
nearly all times of day and all seasons. They also span latitudes and
longitudes from 28 deg. N to 40 deg. N and 95 deg. W to 114 deg. W,
respectively. We have binned and averaged the fluctuation spectra according to
time of day, season, and geomagnetic (Kp index) and solar (F10.7) activity.
These spectra provide a detailed, multi-scale account of seasonal and intraday
variations in ionospheric activity with wavelike structures detected at
wavelengths between about 35 and 250 km. In some cases, trends between spectral
power and Kp index and/or F10.7 are also apparent. In addition, the VLSS
observations allow for measurements of the turbulent power spectrum down to
periods of 40 seconds (scales of ~0.4 km at the height of the E-region). While
the level of turbulent activity does not appear to have a strong dependence on
either Kp index or F10.7, it does appear to be more pronounced during the
winter daytime, summer nighttime, and near dusk during the spring.Comment: accepted for publication in Radio Scienc
Minimizing the Total Completion Time On-line on a Single Machine, Using Restarts
We give an algorithm to minimize the total completion time on-line on a single machine, using restarts, with a competitive ratio of 3/2. The optimal competitive ratio without using restarts is 2 for deterministic algorithms and for randomized algorithms. This is the first restarting algorithm to minimize the total completion time that is proved to be better than an algorithm that does not restart
Percutaneous Radiofrequency Ablation of Osteoid Osteomas with Use of Real-Time Needle Guidance for Accurate Needle Placement: A Pilot Study
Contains fulltext :
97211.pdf (publisher's version ) (Open Access)PURPOSE: To evaluate the accuracy and technical success of positioning a radiofrequency ablation (RFA) electrode in osteoid osteomas by use of a new real-time needle guidance technology combining cone-beam computed tomography (CT) and fluoroscopy. MATERIALS AND METHODS: Percutaneous RFA of osteoid osteomas was performed in five patients (median age 18 years), under general anesthesia, with the use of cone-beam CT and fluoroscopic guidance for electrode positioning. The outcome parameters were technical success, meaning correct needle placement in the nidus; accuracy defined as the deviation (in mm) from the center of the nidus; and clinical outcome at follow-up. RESULTS: In all five cases, positioning was possible within 3 mm of the determined target location (median nidus size 6.8 mm; range 5-10.2 mm). All procedures were technically successful. All patients were free of pain at clinical follow-up. No complications were observed. CONCLUSION: Real-time fluoroscopy needle guidance based on cone-beam CT is a useful tool to accurately position radiofrequency needles for minimally invasive treatment of osteoid osteomas
Large Electric Dipole Moments of Heavy Neutrinos
In many models of CP violation, the electric dipole moment (EDM) of a heavy
charged or neutral lepton could be very large. We present an explicit model in
which a heavy neutrino EDM can be as large as e-cm, or even a factor
of ten larger if fine-tuning is allowed, and use an effective field theory
argument to show that this result is fairly robust. We then look at the
production cross section for these neutrinos, and by rederiving the Bethe-Block
formula, show that they could leave an ionization track. It is then noted that
the first signature of heavy neutrinos with a large EDM would come from
, leading to a very large rate for single photon plus
missing energy events, and the rate and angular distribution are found.
Finally, we look at some astrophysical consequences, including whether these
neutrinos could constitute the UHE cosmic rays and whether their decays in the
early universe could generate a net lepton asymmetry.Comment: 22 pages, 9 figure
BRST quantization of the pure spinor superstring
We present a derivation of the scattering amplitude prescription for the pure
spinor superstring from first principles, both in the minimal and non-minimal
formulations, and show that they are equivalent. This is achieved by first
coupling the worldsheet action to topological gravity and then proceeding to
BRST quantize this system. Our analysis includes the introduction of constant
ghosts and associated auxiliary fields needed to gauge fix symmetries
associated with zero modes. All fields introduced in the process of
quantization can be integrated out explicitly, resulting in the prescriptions
for computing scattering amplitudes that have appeared previously in the
literature. The zero mode insertions in the path integral follow from the
integration over the constant auxiliary fields.Comment: 31 page
Diversification and agrarian change under environmental constraints in rural China: Evidence from a poor township of Beijing municipality
Working paper du GATE 2007-11This article illustrates the impact of changes related to market reforms and environmental policies on the economic structure in rural China by providing a comparative analysis of several villages in a poor township in Beijing municipality. Two main concomitant phenomena are affecting agricultural and non-agricultural choices in the studied area. First, the introduction of market mechanisms is encouraging local population to engage in new activities that are closer to local comparative advantages. Second, rural households are facing new constraints in the form of environmental protection measures, which have weakened traditional insurance channels provided by forest resources and cattle stock. Drawing on household-level survey data and interviews with village heads conducted in ten villages of Labagoumen township in December 2003, this article analyzes households decisions in response to market reforms and environmental constraints. We find large disparities both between villages and households in the diversification process and discuss the reasons of observed inertia in the region, most households still heavily relying on corn production
A novel germline PAX5 single exon deletion in a pediatric patient with precursor B-cell leukemia
- âŠ