135 research outputs found
The Gallium Neutrino Absorption Cross Section and its Uncertainty
In the recent Baksan Experiment on Sterile Transitions (BEST), a suppressed
rate of neutrino absorption on a gallium target was observed, consistent with
earlier results from neutrino source calibrations of the SAGE and GALLEX/GNO
solar neutrino experiments. The BEST collaboration, utilizing a 3.4 MCi 51Cr
neutrino source, found observed-to-expected counting rates at two very short
baselines of R=0.791 plus/minus 0.05 and 0.766 plus/minus 0.05, respectively.
Among recent neutrino experiments, BEST is notable for the simplicity of both
its neutrino spectrum, line neutrinos from an electron-capture source whose
intensity can be measured to a estimated precision of 0.23%, and its absorption
cross section, where the precisely known rate of electron capture to the
gallium ground state, 71Ge(e,nue)71Ga(g.s.), establishes a minimum value.
However, the absorption cross section uncertainty is a common systematic in the
BEST, SAGE, and GALLEX/GNO neutrino source experiments. Here we update that
cross section, considering a variety of electroweak corrections and the role of
transitions to excited states, to establish both a central value and reasonable
uncertainty, thereby enabling a more accurate assessment of the statistical
significance of the gallium anomalies. Results are given for 51Cr and 37Ar
sources. The revised neutrino capture rates are used in a re-evaluation of the
BEST and gallium anomalies.Comment: 21 pages, 5 figure
The BNO-LNGS joint measurement of the solar neutrino capture rate in 71Ga
We describe a cooperative measurement of the capture rate of solar neutrinos
by the reaction 71Ga(\nu_e,e^-)71Ge. Extractions were made from a portion of
the gallium target in the Russian-American Gallium Experiment SAGE and the
extraction samples were transported to the Gran Sasso laboratory for synthesis
and counting at the Gallium Neutrino Observatory GNO. Six extractions of this
type were made and the resultant solar neutrino capture rate was 64
^{+24}_{-22} SNU, which agrees well with the overall result of the gallium
experiments. The major purpose of this experiment was to make it possible for
SAGE to continue their regular schedule of monthly solar neutrino extractions
without interruption while a separate experiment was underway to measure the
response of 71Ga to neutrinos from an 37Ar source. As side benefits, this
experiment proved the feasibility of long-distance sample transport in ultralow
background radiochemical experiments and familiarized each group with the
methods and techniques of the other.Comment: 7 pages, no figures; minor additions in version
Measurement of the Solar Neutrino Capture Rate by the Russian-American Gallium Solar Neutrino Experiment During One Half of the 22-Year Cycle of Solar Activity
We present the results of measurements of the solar neutrino capture rate in
gallium metal by the Russian-American Gallium Experiment SAGE during slightly
more than half of a 22-year cycle of solar activity. Combined analysis of the
data of 92 runs during the 12-year period January 1990 through December 2001
gives a capture rate of solar neutrinos with energy more than 233 keV of 70.8
+5.3/-5.2 (stat.) +3.7/-3.2 (syst.) SNU. This represents only slightly more
than half of the predicted standard solar model rate of 128 SNU. We give the
results of new runs beginning in April 1998 and the results of combined
analysis of all runs since 1990 during yearly, monthly, and bimonthly periods.
Using a simple analysis of the SAGE results combined with those from all other
solar neutrino experiments, we estimate the electron neutrino pp flux that
reaches the Earth to be (4.6 +/- 1.1) E10/(cm^2-s). Assuming that neutrinos
oscillate to active flavors the pp neutrino flux emitted in the solar fusion
reaction is approximately (7.7 +/- 1.8) E10/(cm^2-s), in agreement with the
standard solar model calculation of (5.95 +/- 0.06) E10/(cm^2-s).Comment: English translation of article submitted to Russian journal Zh. Eksp.
Teor. Fiz. (JETP); 12 pages, 5 figures. V2: Added winter-summer difference
and 2 reference
PHYSICOCHEMICAL CHARACTERIZATION OF RIBAVIRIN WITH SPECTROSCOPY AND MOLECULAR MODELING
This work was supported by Mendeleev University of Chemical Technology of Russia. Project Number K-003-2018
Measurement of the solar neutrino capture rate with gallium metal
The solar neutrino capture rate measured by the Russian-American Gallium
Experiment (SAGE) on metallic gallium during the period January 1990 through
December 1997 is 67.2 (+7.2-7.0) (+3.5-3.0) SNU, where the uncertainties are
statistical and systematic, respectively. This represents only about half of
the predicted Standard Solar Model rate of 129 SNU. All the experimental
procedures, including extraction of germanium from gallium, counting of 71Ge,
and data analysis are discussed in detail.Comment: 34 pages including 14 figures, Revtex, slightly shortene
The role of the gut microbiota in the development of type 1 diabetes mellitus
At the beginning of the XXI century, with the advent of technical capabilities and new methods of genes sequencing, the attention of researchers to the study of the human metagenome has significantly increased. The interaction between changes in the qualitative and quantitative composition of the gut microbiota (GM) and various diseases is being actively studied, a search for specific metabolites and genes of microorganisms that may be associated with the development, in particular, of immune-mediated diseases is underway. In recent years, a lot of new data have been published on the possible contribution of gut flora dysbiosis to the development of Type 1 Diabetes Mellitus (T1DM), while the first assumptions were put forward as far back as 1970s. The search for pathogenetic mechanisms of GM influence on the development and progression of T1DM is becoming an increasingly relevant objective, since in recent years the incidence of T1DM is rapidly increasing, which is a serious health problem throughout the world.This review discusses the current ideas about the role of GM in the immunopathogenesis of T1DM, new data on the near-term prospects in the study of the human macrogenome, current ideas about the role of GM in the immunopathogenesis of T1DM, and the possibility of applying this knowledge by the practitioner
Measurement of the solar neutrino capture rate by SAGE and implications for neutrino oscillations in vacuum
The Russian-American solar neutrino experiment has measured the capture rate of neutrinos on metallic gallium in a radiochemical experiment at the Baksan Neutrino Observatory. Eight years of measurement give the result 67.2 (+7.2,-7.0) (+3.5,-3.0) SNU, where the uncertainties are statistical and systematic, respectively. The restrictions these results impose on vacuum neutrino oscillation parameters are given
Slowly evolving, immune-mediated diabetes in 14-year-old patient: a case report
Slowly developing immune-mediated diabetes, often called latent autoimmune diabetes in adults, is characterized by the presence of autoantibodies (ATs) to glutamic acid decarboxylase (GADA), the patient's age at the onset over 35 years, and the absence of the need for insulin therapy for 6-12 months to 6 years from the moment of diagnosis, according to the WHO classification of 2019, refers to hybrid forms of diabetes mellitus (DM). In this article, we present a case history of slowly developing immune-mediated diabetes in a 14-year-old boy who was transferred from metformin monotherapy and a diet with restriction of digestible carbohydrates to the intensified insulin therapy only 4 years after the onset of diabetes mellitus with a glycated hemoglobin (HbA1c) level of less than 6.5% throughout the disease. As a result of the studies, the patient was found to have a homozygous genotype highly predisposing to the development of Type 1 Diabetes Mellitus (T1DM), as well as increased levels of ATs to GADA and tyrosine phosphatase (IA-2A). The initially preserved level of basal C-peptide and the clinical course of the disease in this patient do not allow us to classify this case as a classic variant of the course of Type 1 Diabetes Mellitus
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