We use a sample of 43,690 galaxies selected from the Sloan Digital Sky Survey Data Release 4 to study the systematic effects of specific star formation rate (SSFR) and galaxy size (as measured by the ...half-light radius, r sub(h)) on the mass-metallicity relation. We find that galaxies with high SSFR or large r sub(h) for their stellar mass have systematically lower gas-phase metallicities (by up to 0.2 dex) than galaxies with low SSFR or small r sub(h) We discuss possible origins for these dependencies, including galactic winds/outflows, abundance gradients, environment, and star formation rate efficiencies.
The double beta decay experiment NEMO-3 has compleated data taking in January 2011. The aim of the experiment is to search for the neutrinoless double beta decay and investigate the two-neutrino ...double beta decay in seven different isotopes (100Mo, 82Se, 116Cd, 150Nd, 96Zr, 48Ca and 130Te). After analysis of the most part of available data corresponding to 4.5 yr no evidence for 0νββ decay in 100Mo and 82Se is found. The half-life limits at 90% C.L. are 1.0 × 1024 yr and 3.2 × 1023 yr respectively. The two-neutrino decay half live values were precisely measured for all investigated isotopes.
The spinal muscular atrophy (SMA) region on chromosome 5q13 contains an inverted duplication of about 500 kb, and deleterious mutations in the survival motor neuron 1 (SMN1) gene cause SMA, a common ...lethal childhood neuropathy. We have used a number of approaches to probe the evolutionary history of these genes and show that SMN gene duplication and the appearance of SMN2 occurred at very distinct evolutionary times. Molecular fossil and molecular clock data suggest that this duplication may have occurred as recently as 3 million years ago in that the position and identity repetitive elements are identical for both human SMN genes and overall sequence divergence ranged from 0.15% to 0.34%. However, these approaches ignore the possibility of sequence homogenization by means of gene conversion. Consequently, we have used quantitative polymerase chain rection and analysis of allelic variants to provide physical evidence for or against SMN gene duplication in the chimpanzee, mankind's closest relative. These studies have revealed that chimpanzees have 2-7 copies of the SMN gene per diploid genome; however, the two nucleotides diagnostic for exons 7-8 and the SMNdelta7 mRNA product of the SMN2 gene are absent in non-human primates. In contrast, the SMN2 gene has been detected in all extant human populations studied to date, including representatives from Europe, the Central African Republic, and the Congo. These data provide conclusive evidence that SMN gene duplication occurred more than 5 million years ago, before the separation of human and chimpanzee lineages, but that SMN2 appears for the first time in Homo sapiens.
The full data set of the NEMO-3 experiment has been used to measure the half-life of the two-neutrino double beta decay of Formula omittedMo to the ground state of Formula omittedRu, Formula omitted ...year. The two-electron energy sum, single electron energy spectra and distribution of the angle between the electrons are presented with an unprecedented statistics of Formula omitted events and a signal-to-background ratio of Formula omitted 80. Clear evidence for the Single State Dominance model is found for this nuclear transition. Limits on Majoron emitting neutrinoless double beta decay modes with spectral indices of Formula omitted, as well as constraints on Lorentz invariance violation and on the bosonic neutrino contribution to the two-neutrino double beta decay mode are obtained.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We describe Hubble Space Telescope (HST) imaging of 10 of the 20 ESO Distant Cluster Survey (EDisCS) fields. Each similar to 40 arcmin super(2) field was imaged in the F814W filter with the Advanced ...Camera for Surveys Wide Field Camera. Based on these data, we present visual morphological classifications for the similar to 920 sources per field that are brighter than l sub(auto)= 23 mag. We use these classifications to quantify the morphological content of 10 intermediate-redshift (0.5 < z < 0.8) galaxy clusters within the HST survey region. The EDisCS results, combined with previously published data from seven higher redshift clusters, show no statistically significant evidence for evolution in the mean fractions of elliptical, S0, and late-type (Sp+Irr) galaxies in clusters over the redshift range 0.5 < z < 1.2. In contrast, existing studies of lower redshift clusters have revealed a factor of similar to 2 increase in the typical S0 fraction between z = 0.4 and 0, accompanied by a commensurate decrease in the Sp+Irr fraction and no evolution in the elliptical fraction. The EDisCS clusters demonstrate that cluster morphological fractions plateau beyond z approximately 0.4. They also exhibit a mild correlation between morphological content and cluster velocity dispersion, highlighting the importance of careful sample selection in evaluating evolution. We discuss these findings in the context of a recently proposed scenario in which the fractions of passive (E, S0) and star-forming (Sp, Irr) galaxies are determined primarily by the growth history of clusters.
In this the first of a series of Letters, we present a panchromatic data set in the Extended Groth Strip region of the sky. Our survey, the All-Wavelength Extended Groth Strip International Survey ...(AEGIS), aims to study the physical properties and evolutionary processes of galaxies at z 6 1. It includes the following deep, wide-field imaging data sets: Chandra/ACIS X-ray, GALEX ultraviolet, CFHT/MegaCam Legacy Survey optical, CFHT/CFH12K optical, Hubble Space Telescope/ACS optical and NICMOS near-infrared, Palomar/WIRC near-infrared, Spitzer/IRAC mid-infrared, Spitzer/MIPS far-infrared, and VLA radio continuum. In addition, mis region of the sky has been targeted for extensive spectroscopy using the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II 10 m telescope. Our survey is compared to other large multiwavelength surveys in terms of depth and sky coverage.
The CCube reconstruction algorithm for the SoLid experiment Abreu, Y.; Amhis, Y.; Arnold, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
September 2024, Letnik:
1066
Journal Article
Recenzirano
The SoLid experiment is a very-short-baseline experiment aimed at searching for nuclear-reactor-produced active-to-sterile antineutrino oscillations. The detection principle is based on the pairing ...of two types of solid scintillators: polyvinyl toluene and 6LiF:ZnS(Ag), which is a new technology used in this field of Physics. In addition to good neutron-gamma discrimination, this setup allows the detector to be highly segmented (the basic detection unit is a 5 cm side cube). High segmentation provides numerous advantages, including the precise location of inverse beta decay (IBD) products, the derivation of the antineutrino energy estimator based on the isolated positron energy, and a powerful background reduction tool based on the topological signature of the signal. Finally, the system is read out by a network of wavelength-shifting (WLS) fibres coupled to a photodetectors. This paper describes the design of the reconstruction algorithm that allows maximum use of the granularity of the detector. The goal of the algorithm is to convert the output of the optical-fibre readout to the list of the detection units from which it originated. This paper provides a performance comparison for three methods and concludes with a choice of the baseline approach for the experiment.
Heteroplasmic mtDNA mutations typically act in a recessive way and cause mitochondrial disease only if present above a certain threshold level. We have experimentally investigated to what extent the ...absolute levels of wild-type (WT) mtDNA influence disease manifestations by manipulating TFAM levels in mice with a heteroplasmic mtDNA mutation in the tRNA
gene. Increase of total mtDNA levels ameliorated pathology in multiple tissues, although the levels of heteroplasmy remained the same. A reduction in mtDNA levels worsened the phenotype in postmitotic tissues, such as heart, whereas there was an unexpected beneficial effect in rapidly proliferating tissues, such as colon, because of enhanced clonal expansion and selective elimination of mutated mtDNA. The absolute levels of WT mtDNA are thus an important determinant of the pathological manifestations, suggesting that pharmacological or gene therapy approaches to selectively increase mtDNA copy number provide a potential treatment strategy for human mtDNA mutation disease.
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