4,190 research outputs found
CMB Signals of Neutrino Mass Generation
We propose signals in the cosmic microwave background to probe the type and
spectrum of neutrino masses. In theories that have spontaneous breaking of
approximate lepton flavor symmetries at or below the weak scale, light
pseudo-Goldstone bosons recouple to the cosmic neutrinos after nucleosynthesis
and affect the acoustic oscillations of the electron-photon fluid during the eV
era. Deviations from the Standard Model are predicted for both the total energy
density in radiation during this epoch, \Delta N_nu, and for the multipole of
the n'th CMB peak at large n, \Delta l_n. The latter signal is difficult to
reproduce other than by scattering of the known neutrinos, and is therefore an
ideal test of our class of theories. In many models, the large shift, \Delta
l_n \approx 8 n_S, depends on the number of neutrino species that scatter via
the pseudo-Goldstone boson interaction. This interaction is proportional to the
neutrino masses, so that the signal reflects the neutrino spectrum. The
prediction for \Delta N_nu is highly model dependent, but can be accurately
computed within any given model. It is very sensitive to the number of
pseudo-Goldstone bosons, and therefore to the underlying symmetries of the
leptons, and is typically in the region of 0.03 < \Delta N_nu < 1. This signal
is significantly larger for Majorana neutrinos than for Dirac neutrinos, and,
like the scattering signal, varies as the spectrum of neutrinos is changed from
hierarchical to inverse hierarchical to degenerate.Comment: 40 pages, 4 figure
The rehydration transcriptome of the desiccation-tolerant bryophyte Tortula ruralis: transcript classification and analysis
BACKGROUND: The cellular response of plants to water-deficits has both economic and evolutionary importance directly affecting plant productivity in agriculture and plant survival in the natural environment. Genes induced by water-deficit stress have been successfully enumerated in plants that are relatively sensitive to cellular dehydration, however we have little knowledge as to the adaptive role of these genes in establishing tolerance to water loss at the cellular level. Our approach to address this problem has been to investigate the genetic responses of plants that are capable of tolerating extremes of dehydration, in particular the desiccation-tolerant bryophyte, Tortula ruralis. To establish a sound basis for characterizing the Tortula genome in regards to desiccation tolerance, we analyzed 10,368 expressed sequence tags (ESTs) from rehydrated rapid-dried Tortula gametophytes, a stage previously determined to exhibit the maximum stress induced change in gene expression. RESULTS: The 10, 368 ESTs formed 5,563 EST clusters (contig groups representing individual genes) of which 3,321 (59.7%) exhibited similarity to genes present in the public databases and 2,242 were categorized as unknowns based on protein homology scores. The 3,321 clusters were classified by function using the Gene Ontology (GO) hierarchy and the KEGG database. The results indicate that the transcriptome contains a diverse population of transcripts that reflects, as expected, a period of metabolic upheaval in the gametophyte cells. Much of the emphasis within the transcriptome is centered on the protein synthetic machinery, ion and metabolite transport, and membrane biosynthesis and repair. Rehydrating gametophytes also have an abundance of transcripts that code for enzymes involved in oxidative stress metabolism and phosphorylating activities. The functional classifications reflect a remarkable consistency with what we have previously established with regards to the metabolic activities that are important in the recovery of the gametophytes from desiccation. A comparison of the GO distribution of Tortula clusters with an identical analysis of 9,981 clusters from the desiccation sensitive bryophyte species Physcomitrella patens, revealed, and accentuated, the differences between stressed and unstressed transcriptomes. Cross species sequence comparisons indicated that on the whole the Tortula clusters were more closely related to those from Physcomitrella than Arabidopsis (complete genome BLASTx comparison) although because of the differences in the databases there were more high scoring matches to the Arabidopsis sequences. The most abundant transcripts contained within the Tortula ESTs encode Late Embryogenesis Abundant (LEA) proteins that are normally associated with drying plant tissues. This suggests that LEAs may also play a role in recovery from desiccation when water is reintroduced into a dried tissue. CONCLUSION: The establishment of a rehydration EST collection for Tortula ruralis, an important plant model for plant stress responses and vegetative desiccation tolerance, is an important step in understanding the genome level response to cellular dehydration. The type of transcript analysis performed here has laid the foundation for more detailed functional and genome level analyses of the genes involved in desiccation tolerance in plants
Risk of mature B-cell neoplasms and precursor conditions after joint replacement : a report from the Haematological Malignancy Research Network
Associations between previous joint replacement and B-cell lymphoid malignancies have been reported, but despite numerous reports, associations with the disease subtypes have received little attention. Using a UK-based register of haematological malignancies and a matched general population-based cohort, joint replacements from linked hospital inpatient records were examined. Cases diagnosed 2009-2015 who were aged 50âyears or more were included; 8,013 mature B-cell neoplasms comprising myeloma (n=1,763), diffuse large B-cell lymphoma (DLBCL, n=1,676), chronic lymphocytic leukaemia (CLL, n=1,594), marginal zone lymphoma (MZL, n=957), follicular lymphoma (FL, n=725), and classical Hodgkin lymphoma (CHL, n=255), together with monoclonal gammopathy of uncertain significance (MGUS, n=2,138) and monoclonal B-cell lymphocytosis (MBL, n=632). Odds ratios (OR) and 95% confidence intervals (95%CI) were calculated relative to 10 age- and sex-matched controls using conditional logistic regression. Having had a joint replacement before diagnosis was associated with myeloma (OR=1.3, 95%CI 1.1-1.5, p=0.008) and MGUS (OR=1.3, 95%CI 1.1-1.5, p<0.001). Excluding replacements in the year before diagnosis, the MGUS risk remained, elevated where two or more joints were replaced (OR=1.5, 95%CI 1.2-2.0, p=0.001), with hip (OR=1.2, 95%CI 1.0-1.5, p=0.06) or knee replacements (OR=1.5, 95%CI 1.2-1.8, p<0.001). Associations with CHL and two or more replacements (OR=2.7, 95%CI 1.3-5.6, p=0.005) or hip replacements (OR=1.9, 95%CI 1.0-3.4, p=0.04); and between DLBCL and knee replacements (OR=1.3, 95%CI 1.0-1.6, p=0.04) were also observed. This study reports for the first time a relationship between joint replacements and MGUS; while absolute risks of disease are low and not of major public health concern, these findings warrant further investigation. This article is protected by copyright. All rights reserved
Fermi surfaces in maximal gauged supergravity
We obtain fermion fluctuation equations around extremal charged black hole
geometries in maximal gauged supergravity in four and five dimensions, and we
demonstrate that their solutions display Fermi surface singularities for the
dual conformal field theories at finite chemical potential. The
four-dimensional case is a massless charged fermion, while in five dimensions
we find a massive charged fermion with a Pauli coupling. In both cases, the
corresponding scaling exponent is less than one half, leading to non-Fermi
liquid behavior with no stable quasiparticles, although some excitations have
widths more than ten times smaller than their excitation energy. In the
five-dimensional case, both the Fermi momentum and the scaling exponent appear
to have simple values, and a Luttinger calculation suggests that the gauginos
may carry most of the charge of the black hole.Comment: 6 pages, REVTeX. v2: Introduction expanded, version to appear in
Physical Review Letter
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Experiences and Attitudes of Genome Investigators Regarding Return of Individual Genetic Test Results
Purpose Whether and how to return individual genetic results to study participants is among the most contentious policy issues in contemporary genomic research. Methods: We surveyed corresponding authors of genome-wide association studies (GWAS), identified through the National Human Genome Research Institute's Catalog of Published GWAS, to describe the experiences and attitudes of these stakeholders. Results: Of 357 corresponding authors, 200 (56%) responded. One hundred twenty-six (63%) had been responsible for primary data and sample collection, whereas 74 (37%) had performed secondary analyses. Only 7 (4%) had returned individual results within their index GWAS. Most (69%) believed that return of results to individual participants was warranted under at least some circumstances. Most respondents identified a desire to benefit participants's health (63%) and respect for participants's; desires for information (57%) as major motivations for returning results. Most also identified uncertain clinical utility (76%), the possibility that participants will misunderstand results (74%), the potential for emotional harm (61%), the need to ensure access to trained clinicians (59%), and the potential for loss of confidentiality (51%) as major barriers to return. Conclusion: Investigators have limited experience returning individual results from genome-scale research, yet most are motivated to do so in at least some circumstances
Heterotrophy of oceanic particulate organic matter elevates net ecosystem calcification
Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 46(16), (2019): 9851-9860, doi:10.1029/2019GL083726.Coral reef calcification is expected to decline due to climate change stressors such as ocean acidification and warming. Projections of future coral reef health are based on our understanding of the environmental drivers that affect calcification and dissolution. One such driver that may impact coral reef health is heterotrophy of oceanicâsourced particulate organic matter, but its link to calcification has not been directly investigated in the field. In this study, we estimated net ecosystem calcification and oceanic particulate organic carbon (POCoc) uptake across the KÄne'ohe Bay barrier reef in Hawai'i. We show that higher rates of POCoc uptake correspond to greater net ecosystem calcification rates, even under low aragonite saturation states (Ωar). Hence, reductions in offshore productivity may negatively impact coral reefs by decreasing the food supply required to sustain calcification. Alternatively, coral reefs that receive ample inputs of POCoc may maintain higher calcification rates, despite a global decline in Ωar.Data needed for calculations are available in the supporting information. Additional data can be provided upon request directly from the corresponding author or accessed by links provided in the supporting information. The authors declare no competing financial interests. We thank Texas Sea Grant for providing partial funding for this project to A. Kealoha through the GrantsâInâAid of Graduate Research Program. We also thank the NOAA Nancy Foster Scholarship for PhD program funding to A. Kealoha and Texas A&M University for funds awarded to Shamberger that supported this work. This research was also supported by funding from National Science Foundation Grant OCEâ1538628 to RappĂ©. The Hawaii Institute of Marine Biology (particularly the RappĂ© Lab and Jason Jones), NOAA's Coral Reef Ecosystem Program, Connie Previti, Serena Smith, and Chris Maupin were instrumental in sample collection and data analysis.2020-02-2
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