891 research outputs found
Towards Constraining Parity-Violations in Gravity with Satellite Gradiometry
Parity violation in gravity, if existed, could have important implications,
and it is meaningful to search and test the possible observational effects.
Chern-Simons modified gravity serves as a natural model for gravitational
parity-violations. Especially, considering extensions to Einstein-Hilbert
action up to second order curvature terms, it is known that theories of
gravitational parity-violation will reduce to the dynamical Chern-Simons
gravity. In this letter, we outline the theoretical principles of testing the
dynamical Chern-Simons gravity with orbiting gravity gradiometers, which could
be naturally incorporated into future satellite gravity missions. The secular
gravity gradient signals, due to the Mashhoon-Theiss (anomaly) effect, in
dynamical Chern-Simons gravity are worked out, which can improve the constraint
of the corresponding Chern-Simons length scale
obtained from such measurement scheme. For orbiting superconducting
gradiometers or gradiometers with optical readout, a bound
(or even better) could in principle be
obtained, which will be at least 2 orders of magnitude stronger than the
current one based on the observations from the GP-B mission and the LAGEOS I,
II satellites.Comment: 15 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1606.0818
Application of Dynamic Interface Technology in Scientific Research Management System
Abstractthis paper tries to develop an Internet-based evaluation system for declaration of scientific research projects. The system, employing the integrating mode of C/S and B/S, accomplishes three functions: on-line declaration of scientific research projects, project management and on-line evaluation. The problem of dovetailing word text with database is properly solved. Furthermore, the efficiency of designation of the system is highly raised thanks to the adoption of XML store profile, DOM interface and dynamic interface technology
Phylogenomic reconstruction of lactic acid bacteria: an update
<p>Abstract</p> <p>Background</p> <p>Lactic acid bacteria (LAB) are important in the food industry for the production of fermented food products and in human health as commensals in the gut. However, the phylogenetic relationships among LAB species remain under intensive debate owing to disagreements among different data sets.</p> <p>Results</p> <p>We performed a phylogenetic analysis of LAB species based on 232 genes from 28 LAB genome sequences. Regardless of the tree-building methods used, combined analyses yielded an identical, well-resolved tree topology with strong supports for all nodes. The LAB species examined were divided into two groups. Group 1 included families Enterococcaceae and Streptococcaceae. Group 2 included families Lactobacillaceae and Leuconostocaceae. Within Group 2, the LAB species were divided into two clades. One clade comprised of the acidophilus complex of genus <it>Lactobacillus </it>and two other species, <it>Lb. sakei </it>and <it>Lb. casei</it>. In the acidophilus complex, <it>Lb. delbrueckii </it>separated first, while <it>Lb. acidophilus</it>/<it>Lb. helveticus </it>and <it>Lb. gasseri</it>/<it>Lb. johnsonii </it>were clustered into a sister group. The other clade within Group 2 consisted of the salivarius subgroup, including five species, <it>Lb. salivarius</it>, <it>Lb. plantarum</it>, <it>Lb. brevis</it>, <it>Lb. reuteri</it>, <it>Lb. fermentum</it>, and the genera <it>Pediococcus, Oenococcus</it>, and <it>Leuconostoc</it>. In this clade, <it>Lb. salivarius </it>was positioned most basally, followed by two clusters, one corresponding to <it>Lb. plantarum</it>/<it>Lb. brevis </it>pair and <it>Pediococcus</it>, and the other including <it>Oenococcus</it>/<it>Leuconostoc </it>pair and <it>Lb. reuteri</it>/<it>Lb. fermentum </it>pair. In addition, phylogenetic utility of the 232 genes was analyzed to identify those that may be more useful than others. The genes identified as useful were related to translation and ribosomal structure and biogenesis (TRSB), and a three-gene set comprising genes encoding ultra-violet resistance protein B (<it>uvrB</it>), DNA polymerase III (<it>polC</it>) and penicillin binding protein 2B (<it>pbpB</it>).</p> <p>Conclusions</p> <p>Our phylogenomic analyses provide important insights into the evolution and diversification of LAB species, and also revealed the phylogenetic utility of several genes. We infer that the occurrence of multiple, independent adaptation events in LAB species, have resulted in their occupation of various habitats. Further analyses of more genes from additional, representative LAB species are needed to reveal the molecular mechanisms underlying adaptation of LAB species to various environmental niches.</p
Ginzburg-Landau-type theory of non-polarized spin superconductivity
Since the concept of spin superconductor was proposed, all the related
studies concentrate on spin-polarized case. Here, we generalize the study to
spin-non-polarized case. The free energy of non-polarized spin superconductor
is obtained, and the Ginzburg-Landau-type equations are derived by using the
variational method. These Ginzburg-Landau-type equations can be reduced to the
spin-polarized case when the spin direction is fixed. Moreover, the expressions
of super linear and angular spin currents inside the superconductor are
derived. We demonstrate that the electric field induced by super spin current
is equal to the one induced by equivalent charge obtained from the second
Ginzburg-Landau-type equation, which shows self-consistency of our theory. By
applying these Ginzburg-Landau-type equations, the effect of electric field on
the superconductor is also studied. These results will help us get a better
understanding of the spin superconductor and the related topics such as
Bose-Einstein condensate of magnons and spin superfluidity.Comment: 9 pages, 5 figure
Novel SPP Water Management Strategy and Its Applications
Clean freshwater is the most precious resource in the world and the development of water resources has had a very long history, as early as humans changed from being hunters and food collectors to modern civilization. At very early stage, people had to rely on creeks, rivers and lakes for their water demand that was relatively small, and today humans have accumulated the knowledge and techniques for water storage, building artificial lakes or reservoirs to meet their huge water demand due to industrialization and urbanization. The Wworld’s earliest large dam was the Sadd-el-kafara Dam built in Egypt between 2950 and 2690 B.C. Up to now, water from lakes and reservoirs is still the main source for people’s water supply. However these large water bodies suffer two problems incurred by nature and human being, one is sedimentation and the other water pollution. Two of them jointly reduce the available amount of clean water and deteriorate the water quality. Consequently, approximate 1.1 billion people lack of safe drinking water and between 2 and 5 million people die annually from water-related disease (Gleick, 2004). It is understandable that with the population growth in the world, it is difficult to provide sufficient clean water to meet the demand; on the other hand, our natural systems are under pressure from drought (too little), floods (too much), pollution (too dirty), climate change, and other stresses. This creates serious challenges for water management
Detection of gamma-ray emission from the Coma cluster with Fermi Large Area Telescope and tentative evidence for an extended spatial structure
Many galaxy clusters have giant halos of non-thermal radio emission,
indicating the presence of relativistic electrons in the clusters. Relativistic
protons may also be accelerated by merger and/or accretion shocks in galaxy
clusters. These cosmic-ray (CR) electrons and/or protons are expected to
produce gamma-rays through inverse-Compton scatterings or inelastic
collisions respectively. Despite of intense efforts in searching for
high-energy gamma-ray emission from galaxy clusters, conclusive evidence is
still missing so far. Here we report the discovery of MeV gamma-ray
emission from the Coma cluster direction with an unbinned likelihood analysis
of the 9 years of {\it Fermi}-LAT Pass 8 data. The gamma-ray emission shows a
spatial morphology roughly coincident with the giant radio halo, with an
apparent excess at the southwest of the cluster. Using the test statistic
analysis, we further find tentative evidence that the gamma-ray emission at the
Coma center is spatially extended. The extended component has an integral
energy flux of in the
energy range of 0.2 - 300 GeV and the spectrum is soft with a photon index of
. Interpreting the gamma-ray emission as arising from CR proton
interaction, we find that the volume-averaged value of the CR to thermal
pressure ratio in the Coma cluster is about . Our results show that
galaxy clusters are likely a new type of GeV gamma-ray sources, and they are
probably also giant reservoirs of CR protons.Comment: 10 pages, 10 figures, Accepted by Physical Review D, more spatial
models for the gamma-ray emission are used, systematic checks on the results
are adde
Refined mapping of loss of heterozygosity in Chinese sporadic gastric carcinoma
The aim of this study is to explore precise deleted regions where the candidate tumor suppressor genes might be located in Chinese sporadic gastric carcinoma. By searching in Genothon, NCBI and GDB databases, 145 polymorphic microsatellite markers were chosen, at a mean density of approximately one marker every 2 - 4 cM, covering 15 chromosomes. These polymorphic microsatellite markers in gastric carcinoma and adjacent tissue were analyzed via PCR. PCR products were submitted to electrophoresis on an ABI 3730 DNA sequencer. Genemapper3.2 software was used for LOH (Loss of Heterozygosity) scanning and analysis. Comparison between LOH frequency and clinicopathological factors was performed by Fisher’s exact test. 26 refined regions were mapped as candidate regions for TSGs (Tumor suppression genes) in Chinese sporadic gastric cancer. Associations between LOH and clinical information indicated that 6 loci was associated with pTNM stage, 5 with Lauren's type, 4 with lymph nodes metastasis and another 2 with distant metastasis. Through refined deletion mapping, 26 candidate regions, where TSGs may be located, were found and 17 loci were proposed to be used as clinical markers in Chinese sporadic gastric cancer.Keywords: Gastric carcinoma, refined mapping, loss of heterozygosity (LOH), tumor suppressor genes (TSGs), tumor markersAfrican Journal of Biotechnology Vol. 9(35), pp. 5754-5761, 30 August, 201
Comparative analysis of layered structures in empirical investor networks and cellphone communication networks
Empirical investor networks (EIN) proposed by
\cite{Ozsoylev-Walden-Yavuz-Bildik-2014-RFS} are assumed to capture the
information spreading path among investors. Here, we perform a comparative
analysis between the EIN and the cellphone communication networks (CN) to test
whether EIN is an information exchanging network from the perspective of the
layer structures of ego networks. We employ two clustering algorithms
(-means algorithm and break algorithm) to detect the layer structures
for each node in both networks. We find that the nodes in both networks can be
clustered into two groups, one that has a layer structure similar to the
theoretical Dunbar Circle corresponding to that the alters in ego networks
exhibit a four-layer hierarchical structure with the cumulative number of 5,
15, 50 and 150 from the inner layer to the outer layer, and the other one
having an additional inner layer with about 2 alters compared with the Dunbar
Circle. We also find that the scale ratios, which are estimated based on the
unique parameters in the theoretical model of layer structures
\citep{Tamarit-Cuesta-Dunbar-Sanchez-2018-PNAS}, conform to a log-normal
distribution for both networks. Our results not only deepen our understanding
on the topological structures of EIN, but also provide empirical evidence of
the channels of information diffusion among investors.Comment: 9 pages, 9 figues, 3 table
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