24 research outputs found
Homestake result, sterile neutrinos and low energy solar neutrino experiments
The Homestake result is about ~ 2 \sigma lower than the Ar-production rate,
Q_{Ar}, predicted by the LMA MSW solution of the solar neutrino problem. Also
there is no apparent upturn of the energy spectrum (R \equiv N_{obs}/N_{SSM})
at low energies in SNO and Super-Kamiokande. Both these facts can be explained
if a light, \Delta m^2_{01} ~ (0.2 - 2) \cdot 10^{-5} eV^2, sterile neutrino
exists which mixes very weakly with active neutrinos: \sin^2 2\alpha ~ (10^{-5}
- 10^{-3}). We perform both the analytical and numerical study of the
conversion effects in the system of two active neutrinos with the LMA
parameters and one weakly mixed sterile neutrino. The presence of sterile
neutrino leads to a dip in the survival probability in the intermediate energy
range E = (0.5 - 5) MeV thus suppressing the Be, or/and pep, CNO as well as B
electron neutrino fluxes. Apart from diminishing Q_{Ar} it leads to decrease of
the Ge-production rate and may lead to decrease of the BOREXINO signal and
CC/NC ratio at SNO. Future studies of the solar neutrinos by SNO, SK, BOREXINO
and KamLAND as well as by the new low energy experiments will allow us to check
this possibility. We present a general analysis of modifications of the LMA
energy profile due to mixing with new neutrino states.Comment: Figures 5 and 6 modified, shorter version will be published in PR
High Energy Neutrino Signals of Four Neutrino Mixing
We evaluate the upward shower and muon event rates for two characteristic
four neutrino mixing models for extragalactic neutrinos, as well as for the
atmospheric neutrinos, with energy thresholds of 1 TeV, 10 TeV and 100 TeV. We
show that by comparing the shower to muon event rates, one can distinguish
between oscillation and no-oscillation models. By measuring shower and muon
event rates for energy thresholds of 10 TeV and 100 TeV, and by considering
their ratio, it is possible to use extragalactic neutrino sources to determine
the type of four-flavor mixing pattern. We find that one to ten years of data
taking with kilometer-size detector has a very good chance of providing
valuable information about the physics beyond the Standard Model.Comment: version accepted for publication in Phys. Rev.
Analysis of bimodality in histograms formed from GALLEX and GNO solar neutrino data
A histogram display of the solar neutrino capture-rate measurements made by
the GALLEX experiment appears to be bimodal, but that of the follow-on GNO
experiment does not. To assess the significance of these results, we introduce
a "bimodality index" based on the probability-transform procedure. This
confirms that the GALLEX measurements are indeed bimodal (at the 99.98 percent
confidence level), and that the GNO measurements are not. Tracking the
bimodality index as a function of time shows that the strongest contribution to
bimodality comes from runs 42 to 62, i.e. from the time interval 1995.1 to
1996.9. The bimodality index for the first half (runs 1 through 33) is 2.56,
whereas that for the second half (runs 33 through 65) is 7.05. Power-spectrum
analysis shows a similar distinction: the peaks in the power spectrum formed
from the second half are stronger than those in the power spectrum formed from
the first half, suggesting that bimodality and rotational modulation are
related.Comment: 14 pages, 8 figure
Simultaneous X-Ray and Radio Observations of the Repeating Fast Radio Burst FRB ∼ 180916.J0158+65
Assessment of variation in immunosuppressive pathway genes reveals TGFBR2 to be associated with prognosis of estrogen receptor-negative breast cancer after chemotherapy
Introduction: Tumor lymphocyte infiltration is associated with clinical response to chemotherapy in estrogen receptor (ER) negative breast cancer. To identify variants in immunosuppressive pathway genes associated with prognosis after adjuvant chemotherapy for ER-negative patients, we studied stage I-III invasive breast cancer patients of European ancestry, including 9,334 ER-positive (3,151 treated with chemotherapy) and 2,334 ER-negative patients (1,499 treated with chemotherapy). Methods: We pooled data from sixteen studies from the Breast Cancer Association Consortium (BCAC), and employed two independent studies for replications. Overall 3,610 single nucleotide polymorphisms (SNPs) in 133 genes were genotyped as part of the Collaborative Oncological Gene-environment Study, in which phenotype and clinical data were collected and harmonized. Multivariable Cox proportional hazard regression was used to assess genetic associations with overall survival (OS) and breast
Functional mechanisms underlying pleiotropic risk alleles at the 19p13.1 breast-ovarian cancer susceptibility locus
A locus at 19p13 is associated with breast cancer (BC) and ovarian cancer (OC) risk. Here we analyse 438 SNPs in this region in 46,451 BC and 15,438 OC cases, 15,252 BRCA1 mutation carriers and 73,444 controls and identify 13 candidate causal SNPs associated with serous OC (P=9.2 × 10-20), ER-negative BC (P=1.1 × 10-13), BRCA1-associated BC (P=7.7 × 10-16) and triple negative BC (P-diff=2 × 10-5). Genotype-gene expression associations are identified for candidate target genes ANKLE1 (P=2 × 10-3) and ABHD8 (P<2 × 10-3). Chromosome conformation capture identifies interactions between four candidate SNPs and ABHD8, and luciferase assays indicate six risk alleles increased transactivation of the ADHD8 promoter. Targeted deletion of a region containing risk SNP rs56069439 in a putative enhancer induces ANKLE1 downregulation; and mRNA stability assays indicate functional effects for an ANKLE1 3′-UTR SNP. Altogether, these data suggest that multiple SNPs at 19p13 regulate ABHD8 and perhaps ANKLE1 expression, and indicate common mechanisms underlying breast and ovarian cancer risk