1,246 research outputs found
Research Program towards Observation of Neutrino-Nucleus Coherent Scattering
The article describes the research program pursued by the TEXONO
Collaboration towards an experiment to observe coherent scattering between
neutrinos and the nucleus at the power reactor. The motivations of studying
this process are surveyed. In particular, a threshold of 100-200 eV has been
achieved with an ultra-low-energy germanium detector prototype. This detection
capability at low energy can also be adapted to conduct searches of Cold Dark
Matter in the low-mass region as well as to enhance the sensitivities in the
study of neutrino magnetic moments.Comment: 5 pages, 8 figures ; Proceedings of TAUP-2005 Workshop, Spain, 2005.
Updated on 2006/9/15 for Proceedings of Neutrino-2006 Conference, Santa Fe,
200
Superconducting Superstructure for the TESLA Collider
We discuss the new layout of a cavity chain (superstructure) allowing, we
hope, significant cost reduction of the RF system of both linacs of the TESLA
linear collider. The proposed scheme increases the fill factor and thus makes
an effective gradient of an accelerator higher. We present mainly computations
we have performed up to now and which encouraged us to order the copper model
of the scheme, still keeping in mind that experiments with a beam will be
necessary to prove if the proposed solution can be used for the acceleration.Comment: 11 page
Self-reported chronic kidney disease and the risk of all-cause and cause-specific mortality: Outcome-wide association study of 54 causes of death in the National Health Interview Survey
Background: A diagnosis of chronic kidney disease has been strongly associated with cardiovascular disease and mortality in a number of studies, but the association with specific causes of death has not been assessed in detail. We analysed the association between chronic kidney disease and all-cause mortality and 54 causes of death in the National Health Interview Survey, a prospective study of 210,748 US adults. Methods: We used multivariable Cox regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and cause-specific mortality associated with self-reported chronic kidney disease. Men and women aged 18–84 years were recruited between 1997 and 2004 and followed up for mortality through December 31, 2006. Results: During an average of 6 years follow-up, 9564 deaths occurred. A history of chronic kidney disease vs. no chronic kidney disease was associated with increased risk of all-cause mortality (HR = 2.69, 95% CI: 2.38–3.04), and mortality from septicemia (5.65, 2.84–11.25), viral hepatitis (10.67, 2.43–46.95), other infectious parasitic diseases (10.58, 3.59–31.21), total cancer (1.48, 1.05–2.09), lung cancer (1.94, 1.10–3.44), kidney cancer (4.74, 1.81–12.41), diabetes mellitus (8.57, 5.60–13.11), circulatory disease overall (3.36, 2.70–4.18) and 11 specific circulatory diseases with the strongest associations observed for primary hypertension/renal disease (13.60, 6.42–28.84), hypertensive heart/renal disease (10.72, 2.47–46.49), and other diseases of circulatory system (7.36, 3.22–16.81). Elevated risk was also observed for alcoholic liver disease (5.63, 1.90–16.66), other chronic liver disease (4.41, 1.74–11.17), kidney failure (13.07, 8.23–20.77), and five other causes of death. Conclusions: A history of chronic kidney disease was associated with increased risk of all-cause mortality and 27 out of 54 causes of death. Further studies are needed to clarify associations with less common causes of death
Body mass index measured repeatedly over 42 years as a risk factor for ischemic stroke: the HUNT study.
BACKGROUND: Higher BMI in middle age is associated with ischemic stroke, but little is known about BMI over adulthood, and the risk for ischemic stroke as most studies relied on a single measurement of BMI. METHODS: BMI was measured four times over a period of 42 years. We calculated average BMI values and group-based trajectory models and related these to the prospective risk of ischemic stroke after the last examination in Cox models with a follow-up time of 12 years. RESULTS: A total of 14,139 participants, with a mean age of 65.2 years and 55.4% women, had information on BMI from all four examinations, and we observed 856 ischemic strokes. People with overweight and obesity over adulthood had a higher risk for ischemic stroke with a multivariable-adjusted hazard ratio of 1.29 (95% CI 1.11-1.48) and 1.27 (95% CI 0.96-1.67), respectively, when compared to normal weight participants. Excess weight tended to have stronger effects earlier than later in life. A trajectory of developing obesity throughout life was associated with higher risk than other trajectories. CONCLUSIONS: High average BMI, especially at an early age, is a risk factor for ischemic stroke. Early weight control and long-term weight reduction for those with high BMI may decrease the later occurrence of ischemic stroke
Improvement Of Cavity Performance By Electro-polishing In The 1.3ghz Nb Superconducting Cavities
The Study of TeV Variability and Duty Cycle of Mrk 421 from 3 Years of Observations with the Milagro Observatory
TeV flaring activity with time scales as short as tens of minutes and an
orphan TeV flare have been observed from the blazar Markarian 421 (Mrk 421).
The TeV emission from Mrk 421 is believed to be produced by leptonic
synchrotron self-Compton (SSC) emission. In this scenario, correlations between
the X-ray and the TeV fluxes are expected, TeV orphan flares are hardly
explained and the activity (measured as duty cycle) of the source at TeV
energies is expected to be equal or less than that observed in X-rays if only
SSC is considered. To estimate the TeV duty cycle of Mrk 421 and to establish
limits on its variability at different time scales, we continuously observed
Mrk 421 with the Milagro observatory. Mrk 421 was detected by Milagro with a
statistical significance of 7.1 standard deviations between 2005 September 21
and 2008 March 15. The observed spectrum is consistent with previous
observations by VERITAS. We estimate the duty cycle of Mrk 421 for energies
above 1 TeV for different hypothesis of the baseline flux and for different
flare selections and we compare our results with the X-ray duty cycle estimated
by Resconi et al. 2009. The robustness of the results is discussed.Comment: 27 pages, 6 figures, ApJ accepte
Discovery of Localized Regions of Excess 10-TeV Cosmic Rays
An analysis of 7 years of Milagro data performed on a 10-degree angular scale
has found two localized regions of excess of unknown origin with greater than
12 sigma significance. Both regions are inconsistent with gamma-ray emission
with high confidence. One of the regions has a different energy spectrum than
the isotropic cosmic-ray flux at a level of 4.6 sigma, and it is consistent
with hard spectrum protons with an exponential cutoff, with the most
significant excess at ~10 TeV. Potential causes of these excesses are explored,
but no compelling explanations are found.Comment: Submitted to PhysRevLet
Astroclimatic Characterization of Vallecitos: A candidate site for the Cherenkov Telescope Array at San Pedro Martir
We conducted an 18 month long study of the weather conditions of the
Vallecitos, a proposed site in Mexico to harbor the northern array of the
Cherenkov Telescope Array (CTA). It is located in Sierra de San Pedro Martir
(SPM) a few kilometers away from Observatorio Astron\'omico Nacional. The study
is based on data collected by the ATMOSCOPE, a multi-sensor instrument
measuring the weather and sky conditions, which was commissioned and built by
the CTA Consortium. Additionally, we compare the weather conditions of the
optical observatory at SPM to the Vallecitos regarding temperature, humidity,
and wind distributions. It appears that the excellent conditions at the optical
observatory benefit from the presence of microclimate established in the
Vallecitos.Comment: 16 pages, 16 figures, Publication of the Astronomical Society of the
Pacific, accepte
Productivity of pigeon pea and maize rotation system in Balaka District, Southern Malawi
In Malawi, some parts of the country, such as Balaka District in Southern Malawi, are particularly prone to erratic rains with poor soil productivity. In the 2015/2016 rainy season some learning centres (LCs) focusing on pigeon-pea (Cajanus cajan) – maize (Zea mays L) rotations were established in four sections of Ulongwe Agriculture Extension Planning Area (EPA) in Balaka District to enhance soil fertility, nutrition and income diversification for increased resilience to production under erratic rain condition. Up to 132 plots of pigeon were established in 2005/2016 season. Of these 44 fields were sampled for yield, biomass, plant stand and 32 sites for soil data. In the second season of 2016/17, a maize fertilizer response trial with five rates of NPKS (0, 23:21:0+4S, 46:21:0+4S, 69:21:0+4S, and 92:21:0+4S) was super-imposed in the 44 fields, where farmers incorporated pigeon pea residues, a parallel study conducted in a nearby, adjacent field. In the first season, rainfall was low and erratic. Three dry spells (>10 non-rainy days) were recorded in two of four rain gauge stations, and two dry spells in one station. The soil test results showed low P, K and N status. Pigeon pea plant stand was low, with an average of 2.22 plants m-2 compared to an expected 4.44 plants m-2. Grain yields and stover weights were quite variable with a mean of 442 and 1698 kg/ha, respectively. In the second season maize yields grown in both old pigeon pea or continuous maize plots gave a linear response to fertilizer. The gains from pigeon rotation averaged 620, 308, 496 and -1072 for Chibwana Nsamala, Hindahinda, Mulambe and Chitseko sections respectively. The highest recorded yield was 4049 kg/ha from Hindahinda
Spectrum and Morphology of the Two Brightest Milagro Sources in the Cygnus Region: MGRO J2019+37 and MGRO J2031+41
The Cygnus region is a very bright and complex portion of the TeV sky, host
to unidentified sources and a diffuse excess with respect to conventional
cosmic-ray propagation models. Two of the brightest TeV sources, MGRO J2019+37
and MGRO J2031+41, are analyzed using Milagro data with a new technique, and
their emission is tested under two different spectral assumptions: a power law
and a power law with an exponential cutoff. The new analysis technique is based
on an energy estimator that uses the fraction of photomultiplier tubes in the
observatory that detect the extensive air shower. The photon spectrum is
measured in the range 1 to 200 TeV using the last 3 years of Milagro data
(2005-2008), with the detector in its final configuration. MGRO J2019+37 is
detected with a significance of 12.3 standard deviations (), and is
better fit by a power law with an exponential cutoff than by a simple power
law, with a probability % (F-test). The best-fitting parameters for the
power law with exponential cutoff model are a normalization at 10 TeV of
, a spectral
index of and a cutoff energy of TeV. MGRO
J2031+41 is detected with a significance of 7.3, with no evidence of a
cutoff. The best-fitting parameters for a power law are a normalization of
and a
spectral index of . The overall flux is subject to an
30% systematic uncertainty. The systematic uncertainty on the power law
indices is 0.1. A comparison with previous results from TeV J2032+4130,
MGRO J2031+41 and MGRO J2019+37 is also presented.Comment: 11 pages, 10 figure
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