137 research outputs found
Black holes in the varying speed of light theory
We consider the effect of the \emph{Varying Speed of Light} theory on
non-rotating black holes. We show that in any varying- theory, the
Schwarzschild solution is neither static nor stationary. For a no-charged black
hole, the singularity in the Schwarzschild horizon cannot be removed by
coordinate transformation. Hence, no matter can enter the horizon, and the
interior part of the black hole is separated from the rest of the Universe. If
, then the size of the Schwarzschild radius increases with time. The
higher value of the speed of light in the very early Universe may have caused a
large reduction in the probability of the creation of the primordial black
holes and their population.The same analogy is also considered for the charged
black holes.Comment: 5 page
Statin therapy in chronic viral hepatitis: a systematic review and meta-analysis of nine studies with 195,602 participants
Background: Conflicting data suggest that statins could cause chronic liver disease in certain group of patients, while improving prognosis in those with chronic viral hepatitis (CVH).
Purpose: To quantify the potential protective role of statins on some main liver-related health outcomes in clinical studies on CVH patients.Data Sources: The search strategy was explored by a medical librarian using bibliographic databases, from January 2015 to April 2020.Data synthesis: The results showed no significant difference in the risk of mortality between statin users and non-users in the overall analysis. However, the risk of mortality significantly reduced by 39% in statin users who were followed for more than three years. Moreover, the risk of HCC, fibrosis, and cirrhosis in those on statins decreased by 53%, 45% and 41%, respectively. Although ALT and AST reduced slightly following statin therapy, this reduction was not statistically significant.
Limitations: A significant heterogeneity among studies was observed, resulting from differences in clinical characteristics between statin users and non-users, study designs, population samples, diseases stage, comorbidities, and confounding covariates.
Conclusion: Not only long-term treatment with statins seems to be safe in patients affected by hepatitis, but also it significantly improves their prognosis
THINK Back: KNowledge-based Interpretation of High Throughput data
Results of high throughput experiments can be challenging to interpret. Current approaches have relied on bulk processing the set of expression levels, in conjunction with easily obtained external evidence, such as co-occurrence. While such techniques can be used to reason probabilistically, they are not designed to shed light on what any individual gene, or a network of genes acting together, may be doing. Our belief is that today we have the information extraction ability and the computational power to perform more sophisticated analyses that consider the individual situation of each gene. The use of such techniques should lead to qualitatively superior results
Chameleonic Generalized Brans--Dicke model and late-time acceleration
In this paper we consider Chameleonic Generalized Brans--Dicke Cosmology in
the framework of FRW universes. The bouncing solution and phantom crossing is
investigated for the model. Two independent cosmological tests: Cosmological
Redshift Drift (CRD) and distance modulus are applied to test the model with
the observation.Comment: 20 pages, 15 figures, to be published in Astrophys. Space Sci. (2011
FRW Cosmology From Five Dimensional Vacuum Brans-Dicke Theory
We follow approach of induced matter theory for 5D vacuum BD, introduce
induced matter and potential in 4D hypersurfaces, and employ generalized FRW
type solution. We confine ourselves to scalar field and scale factors be
functions of the time. This makes the induced potential, by its definition,
vanishes. When the scale factor of fifth dimension and scalar field are not
constants, 5D eqs for any geometry admit a power law relation between scalar
field and scale factor of fifth dimension. Hence the procedure exhibits that 5D
vacuum FRW like eqs are equivalent, in general, to corresponding 4D vacuum ones
with the same spatial scale factor but new scalar field and coupling constant.
We show that 5D vacuum FRW like eqs or its equivalent 4D vacuum ones admit
accelerated solutions. For constant scalar field, eqs reduce to usual FRW eqs
with typical radiation dominated universe. For this situation we obtain
dynamics of scale factors for any geometry without any priori assumption. For
nonconstant scalar fields and spatially flat geometries, solutions are found to
be power law and exponential ones. We also employ weak energy condition for
induced matter, that allows negative/positive pressures. All types of solutions
fulfill WEC in different ranges. The power law solutions with negative/positive
pressures admit both decelerating and accelerating ones. Some solutions accept
shrinking extra dimension. By considering nonghost scalar fields and recent
observational measurements, solutions are more restricted. We illustrate that
accelerating power law solutions, which satisfy WEC and have nonghost fields,
are compatible with recent observations in ranges -4/3 < \omega </- -1.3151 and
1.5208 </- n < 1.9583 for dependence of fifth dimension scale factor with usual
scale factor. These ranges also fulfill condition nonghost fields in the
equivalent 4D vacuum BD eqs.Comment: 18 pages, 16 figures, 11 table
Genetic and metabolomic architecture of variation in diet restriction-mediated lifespan extension in Drosophila.
In most organisms, dietary restriction (DR) increases lifespan. However, several studies have found that genotypes within the same species vary widely in how they respond to DR. To explore the mechanisms underlying this variation, we exposed 178 inbred Drosophila melanogaster lines to a DR or ad libitum (AL) diet, and measured a panel of 105 metabolites under both diets. Twenty four out of 105 metabolites were associated with the magnitude of the lifespan response. These included proteinogenic amino acids and metabolites involved in Îą-ketoglutarate (Îą-KG)/glutamine metabolism. We confirm the role of Îą-KG/glutamine synthesis pathways in the DR response through genetic manipulations. We used covariance network analysis to investigate diet-dependent interactions between metabolites, identifying the essential amino acids threonine and arginine as hub metabolites in the DR response. Finally, we employ a novel metabolic and genetic bipartite network analysis to reveal multiple genes that influence DR lifespan response, some of which have not previously been implicated in DR regulation. One of these is CCHa2R, a gene that encodes a neuropeptide receptor that influences satiety response and insulin signaling. Across the lines, variation in an intronic single nucleotide variant of CCHa2R correlated with variation in levels of five metabolites, all of which in turn were correlated with DR lifespan response. Inhibition of adult CCHa2R expression extended DR lifespan of flies, confirming the role of CCHa2R in lifespan response. These results provide support for the power of combined genomic and metabolomic analysis to identify key pathways underlying variation in this complex quantitative trait
Determinants of Mosaic Chromosomal alteration Fitness
Clonal hematopoiesis (CH) is characterized by the acquisition of a somatic mutation in a hematopoietic stem cell that results in a clonal expansion. These driver mutations can be single nucleotide variants in cancer driver genes or larger structural rearrangements called mosaic chromosomal alterations (mCAs). The factors that influence the variations in mCA fitness and ultimately result in different clonal expansion rates are not well understood. We used the Passenger-Approximated Clonal Expansion Rate (PACER) method to estimate clonal expansion rate as PACER scores for 6,381 individuals in the NHLBI toPMed cohort with gain, loss, and copy-neutral loss of heterozygosity mCAs. Our mCA fitness estimates, derived by aggregating per-individual PACER scores, were correlated (
Identification of circulating proteins associated with general cognitive function among middle-aged and older adults
Identifying circulating proteins associated with cognitive function may point to biomarkers and molecular process of cognitive impairment. Few studies have investigated the association between circulating proteins and cognitive function. We identify 246 protein measures quantified by the SomaScan assay as associated with cognitive function (p < 4.9E-5, n up to 7289). Of these, 45 were replicated using SomaScan data, and three were replicated using Olink data at Bonferroni-corrected significance. Enrichment analysis linked the proteins associated with general cognitive function to cell signaling pathways and synapse architecture. Mendelian randomization analysis implicated higher levels of NECTIN2, a protein mediating viral entry into neuronal cells, with higher Alzheimerâs disease (AD) risk (p = 2.5E-26). Levels of 14 other protein measures were implicated as consequences of AD susceptibility (p < 2.0E-4). Proteins implicated as causes or consequences of AD susceptibility may provide new insight into the potential relationship between immunity and AD susceptibility as well as potential therapeutic targets
Casual Compressive Sensing for Gene Network Inference
We propose a novel framework for studying causal inference of gene
interactions using a combination of compressive sensing and Granger causality
techniques. The gist of the approach is to discover sparse linear dependencies
between time series of gene expressions via a Granger-type elimination method.
The method is tested on the Gardner dataset for the SOS network in E. coli, for
which both known and unknown causal relationships are discovered
Identification of Circulating Proteins associated With General Cognitive Function among Middle-Aged and Older adults
Identifying circulating proteins associated with cognitive function may point to biomarkers and molecular process of cognitive impairment. Few studies have investigated the association between circulating proteins and cognitive function. We identify 246 protein measures quantified by the SomaScan assay as associated with cognitive function (pâ\u3câ4.9E-5, n up to 7289). Of these, 45 were replicated using SomaScan data, and three were replicated using Olink data at Bonferroni-corrected significance. Enrichment analysis linked the proteins associated with general cognitive function to cell signaling pathways and synapse architecture. Mendelian randomization analysis implicated higher levels of NECTIN2, a protein mediating viral entry into neuronal cells, with higher Alzheimer\u27s disease (AD) risk (pâ=â2.5E-26). Levels of 14 other protein measures were implicated as consequences of AD susceptibility (pâ\u3câ2.0E-4). Proteins implicated as causes or consequences of AD susceptibility may provide new insight into the potential relationship between immunity and AD susceptibility as well as potential therapeutic targets
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