80 research outputs found
Thermodynamic properties of higher-dimensional dS black holes in dRGT massive gravity
On the basis of the state parameter of de Sitter space-time satisfying the
first law of thermodynamics,we can derive some effective thermodynamic
quantities.When the temperature of the black hole horizon is equal to that of
the cosmological horizon, we think that the effective temperature of the
space-time should have the same value. Using this condition, we obtain a
differential equation of the entropy of the de Sitter black hole in the
higherdimensional de Rham, Gabadadze and Tolley (dRGT) massive gravity. Solving
the differential equation, we obtain the corrected entropy and effective
thermodynamic quantities of the de Sitter black hole. The results show that for
multiparameter black holes, the entropy satisfied differential equation is
invariable with different independent state parameters. Therefore, the entropy
of higher-dimensional dS black holes in dRGT massive gravity is only a function
of the position of the black hole horizon, and is independent of other state
parameters. It is consistent with the corresponding entropy of the black hole
horizon and the cosmological horizon. The thermodynamic quantities of
self-consistent de Sitter spacetime are given theoretically, and the equivalent
thermodynamic quantities have the second-order phase transformation similar to
AdS black hole, but unlike AdS black hole, the equivalent temperature of de
Sitter space-time has a maximum value. By satisfying the requirement of
thermodynamic equilibrium and stability of space-time, the conditions for the
existence of dS black holes in the universe are obtained.Comment: 11 pages, 6 figure
Phase transition and entropic force of de Sitter black hole in massive gravity
It is well known that de Sitter(dS) black holes generally have a black hole
horizon and a cosmological horizon, both of which have Hawking radiation. But
the radiation temperature of the two horizons is generally different, so dS
black holes do not meet the requirements of thermal equilibrium stability,
which brings certain difficulties to the study of the thermodynamic
characteristics of black holes. In this paper, dS black hole is regarded as a
thermodynamic system, and the effective thermodynamic quantities of the system
are obtained. The influence of various state parameters on the effective
thermodynamic quantities in the massive gravity space-time is discussed. The
condition of the phase transition of the de Sitter black hole in massive
gravity space-time is given. We consider that the total entropy of the dS black
hole is the sum of the corresponding entropy of the two horizons plus an extra
term from the correlation of the two horizons. By comparing the entropic force
of interaction between black hole horizon and the cosmological horizon with
Lennard-Jones force between two particles, we find that the change rule of
entropic force between the two system is surprisingly the same. The research
will help us to explore the real reason of accelerating expansion of the
universe.Comment: 14 pages,11 figure
Bis(triphenylstannyl) thiophene-2,5-dicarboxylate
Molecules of the title compound, [Sn2(C6H5)6(C6H2O4S)], lie on inversion centres with the central thiophene ring disordered equally over two orientations. The carboxylate groups are approximately coplanar with the thiophene ring [dihedral angle = 4.0 (1)°] and the Sn—O bond distance of 2.058 (4) Å is comparable to that in related organotin carboxylates
Biodiversity of wild alfalfa pollinators and their temporal foraging characters in Hexi Corridor, Northwest China
Seed production of alfalfa (Medicago sativa L.) is important in determining the effective distribution of new cultivars to farmers. However, little is known about the biodiversity and their community function of native wild pollinators of alfalfa in agronomic systems. We investigated the biodiversity of insects which visited alfalfa flowers and their temporal foraging characters in Hexi Corridor, China. A high biodiversity of insect visitors was discovered, 20 insect taxa in all, including 13 species of Hymenoptera, 3 species of Coleoptera, 3 species of Lepidoptera and 1 species of Diptera. Three native bee species, Andrena squamata, Anthophora melanognatha and Megachile abluta,were validated as the principal pollinators. They showed significant variations in tripping mode and their diurnal distribution patterns. Our results indicated that the native wild bees are diverse and they complement each other. This means they have developed a more complex system for the pollination of alfalfa than has been previously found out
Comprehensive molecular diagnosis of 67 Chinese Usher syndrome probands: high rate of ethnicity specific mutations in Chinese USH patients
Both Novel missense alleles identified in MYO7A genes are conserved between human, zebrafish and Drosophila melanogaster. (PPTX 676 kb
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CO2 emissions from karst cascade hydropower reservoirs: mechanisms and reservoir effect
Carbon dioxide (CO2) emissions from aquatic surface to the atmosphere has been recognized as a significant factor contributing to the global carbon budget and environmental change. The influence of river damming on the CO2 emissions from reservoirs remains poorly constrained. This is hypothetically due to the change of hydraulic retention time (HRT) and thermal stratification intensity of reservoirs (related to the normal water level, NWL). To test this hypothesis, we quantified CO2 fluxes and related parameters in eight karst reservoirs on the Wujiang River, Southwest China. Our results showed that there was a significant difference in the values of pCO2 (mean = 3205.7 μatm, SD = 2183.4 μatm) and δ13CCO2 (mean = −18.9‰, SD = 1.6‰) in the cascade reservoirs, suggesting that multiple processes regulate CO2 production. Moreover, the calculated CO2 fluxes showed obvious spatiotemporal variations, ranging from −9.0 to 2269.3 mmol m−2 d−1, with an average of 260.1 mmol m−2 d−1. Interestingly, the CO2 flux and δ13CCO2 from reservoirs of this study and other reservoirs around the world had an exponential function with the reservoir effect index (Ri, HRT/NWL), suggesting the viability of our hypothesis on reservoir CO2 emission. This empirical function will help to estimate CO2 emissions from global reservoirs and provide theoretical support for reservoir regulation to mitigate carbon emission
Network Modeling Identifies Molecular Functions Targeted by miR-204 to Suppress Head and Neck Tumor Metastasis
Due to the large number of putative microRNA gene targets predicted by sequence-alignment databases and the relative low accuracy of such predictions which are conducted independently of biological context by design, systematic experimental identification and validation of every functional microRNA target is currently challenging. Consequently, biological studies have yet to identify, on a genome scale, key regulatory networks perturbed by altered microRNA functions in the context of cancer. In this report, we demonstrate for the first time how phenotypic knowledge of inheritable cancer traits and of risk factor loci can be utilized jointly with gene expression analysis to efficiently prioritize deregulated microRNAs for biological characterization. Using this approach we characterize miR-204 as a tumor suppressor microRNA and uncover previously unknown connections between microRNA regulation, network topology, and expression dynamics. Specifically, we validate 18 gene targets of miR-204 that show elevated mRNA expression and are enriched in biological processes associated with tumor progression in squamous cell carcinoma of the head and neck (HNSCC). We further demonstrate the enrichment of bottleneckness, a key molecular network topology, among miR-204 gene targets. Restoration of miR-204 function in HNSCC cell lines inhibits the expression of its functionally related gene targets, leads to the reduced adhesion, migration and invasion in vitro and attenuates experimental lung metastasis in vivo. As importantly, our investigation also provides experimental evidence linking the function of microRNAs that are located in the cancer-associated genomic regions (CAGRs) to the observed predisposition to human cancers. Specifically, we show miR-204 may serve as a tumor suppressor gene at the 9q21.1–22.3 CAGR locus, a well established risk factor locus in head and neck cancers for which tumor suppressor genes have not been identified. This new strategy that integrates expression profiling, genetics and novel computational biology approaches provides for improved efficiency in characterization and modeling of microRNA functions in cancer as compared to the state of art and is applicable to the investigation of microRNA functions in other biological processes and diseases
Some inequalities involving the polygamma functions
Abstract Let ψn(x)=(−1)n−1ψ(n)(x) , where ψ(n)(x) are the polygamma functions. We determine necessary and sufficient conditions for the monotonicity and convexity of the function F(x;α,β)=ln(exp(αψ(x+β))ψn(x))−ln(n−1)!,x>max(0,−β), for α and β∈R , where ψ(x) is the psi function. Consequently, this yields not only some new inequalities for the polygamma functions, but also new star-shaped and superadditive functions involving them. In addition, we improve a well-known mean-value inequality for the polygamma functions
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