275 research outputs found
Analytical study of the holographic superconductor from higher derivative theory
In this paper, we analytically study the holographic superconductor models
with the high derivative (HD) coupling terms. Using the Sturm-Liouville (SL)
eigenvalue method, we perturbatively calculate the critical temperature. The
analytical results are in good agreement with the numerical results. It
confirms that the perturbative method in terms of the HD coupling parameters is
available. Along the same line, we analytically calculate the value of the
condensation near the critical temperature. We find that the phase transition
is second order with mean field behavior, which is independent of the HD
coupling parameters. Then in the low temperature limit, we also calculate the
conductivity, which is qualitatively consistent with the numerical one. We find
that the superconducting energy gap is proportional to the value of the
condensation. But we note that since the condensation changes with the HD
coupling parameters, as the function of the HD coupling parameters, the
superconducting energy gap follows the same change trend as that of the
condensation.Comment: 10 pages, 5 figure
Signaling for conferencing in mobile ad hoc networks
Mobile Ad hoc NETworks (MANETs) are networks that do not need to be pre-configured. They are composed of transient nodes connected through wireless interfaces. Due to their flexibility, the ease to build and the associated low cost, they are gaining more and more momentum. They are also seen as part of the fourth generation wireless networks. New applications, such as conferencing, are emerging for such networks. Conferencing enables a set of applications such as audio/video conferencing, debating, distance-learning and multi-party gaming. The implementation of conferencing in MANETs is not an easy task due to scarce network resources, heterogeneous devices, frequently changing topology and unstable wireless connections. It challenges each technical aspect of conferencing: signaling, media handling and conference control. Signaling is the control component of conferencing. It handles the session initiation, modification and termination. In this work, we focus on signaling for conferencing in MANETs. Two types of MANETs are considered: standalone MANETs and integrated MANETs/3G networks. Background information is provided, requirements are derived and the state of the art, including signaling protocols such as SIP and H.323, are reviewed. Since there is no existing solution that meets all of the derived requirements, we propose a novel cluster-based signaling architecture that meets the requirements of signaling for standalone MANETs. The clusters are application-layer clusters that are dynamically created and deleted for a conference. We also propose a signaling architectures for integrated MANETs/3G networks. The solution is based on conference gateways. We implement the architectures using SIP extensions. Experimental results are obtained from prototypes and OPNET based simulations. In the prototype, we built the signaling system on a small scale network using IEEE 802.11 ad hoc settings. In the OPNET simulation, we use MANET features. From experiments, we found that clustering is a very promising approach for solving signaling problems in MANETs. Being aware of several performance issues of our signaling systems, we further propose optimization schemes that are based on cross-layer design. We also implement some of these schemes and apply them to our signaling systems. The evaluation shows that the schemes significantly improve the signaling performance
Signaling for multiparty sessions in peer-to-peer ad hoc networks
Multiparty sessions are the basis of several important applications. Audio/video conferencing, distance learning and gaming are some of the examples. So far, very little attention has been devoted to the applications for ad hoc networks. In contrast to conventional networks, ad hoc networks are formed by a set of devices that communicate without using a pre-existing network infrastructure. Multiparty session control faces new challenges in ad hoc networks: peer-to-peer communication, limited resources and transient network connectivity. This thesis addresses the most critical component of multiparty sessions in peer-to-peer ad hoc networks: signaling. Signaling requirements are derived and existing signaling protocols such as SIP, H.323 and ICEBERG signaling are analyzed. By discussing and comparing alternative signaling architectures, we propose a novel signaling scheme based on clustering architecture. The signaling scheme is implemented as an extension to SIP. A prototype is built to evaluate the feasibility and performance of the signaling scheme
Dietary Niacin Supplementation Suppressed Hepatic Lipid Accumulation in Rabbits
An experiment was conducted to investigate the effect of niacin supplementation on hepatic lipid metabolism in rabbits. Rex Rabbits (90 d, n = 32) were allocated to two equal treatment groups: Fed basal diet (control) or fed basal diet with additional 200 mg/kg niacin supplementation (niacin). The results show that niacin significantly increased the levels of plasma adiponectin, hepatic apoprotein B and hepatic leptin receptors mRNA (p0.05). However, niacin treatment significantly inhibited the hepatocytes lipid accumulation compared with the control group (p<0.05). In conclusion, niacin treatment can decrease hepatic fatty acids synthesis, but does not alter fatty acids oxidation and triacylglycerol export. And this whole process attenuates lipid accumulation in liver. Besides, the hormones of insulin, leptin and adiponectin are associated with the regulation of niacin in hepatic lipid metabolism in rabbits
RESTful Web Services for Service Provisioning in Next Generation Networks: A Survey
Next Generation Networks (NGNs), as envisioned by ITU-T, are packet-based networks, capable of provisioning consistent and ubiquitous services to end-users, independently of the network, the access technology and the devices used. RESTful Web services are now being contemplated as a technology for service provisioning in NGNs. They are emerging as an alternative, which may be more adequate than SOAPbased Web services in some cases. SOAP-based Web services are modular applications that can be discovered and invoked over a network. RESTful Web services, on the other hand, are defined as a network architectural style for distributed hypermedia systems. This paper presents a survey on RESTful Web services for service provisioning in NGNs. It introduces the concept of RESTful Web services and reviews the state-of-the-art of RESTful-based-service provisioning in NGNs. It also provides an evaluation of the overall suitability of RESTful Web services for service provisioning in NGNs, and discusses research directions. RESTful Web services do show significant potential for service provisioning in NGNs. However, open issues such as publication/discovery and mechanisms for the development of complex session-based services need to be solved before its full potential can be realized
Research progress on the role of PKM2 in the immune response
Pyruvate kinase (PK) is a key enzyme that catalyzes the dephosphorylation of phosphoenolpyruvate (PEP) into pyruvate, and is responsible for the production of ATP during glycolysis. As another important isozyme of PK, pyruvate kinase M2 (PKM2) exists in cells with high levels of nucleic acid synthesis, such as normal proliferating cells (e.g., lymphocytes and intestinal epithelial cells), embryonic cells, adult stem cells, and tumor cells. With further research, PKM2, as an important regulator of cellular pathophysiological activity, has attracted increasing attention in the process of autoimmune response and inflammatory. In this re]view, we examine the contribution of PKM2 to the human immune response. Further studies on the immune mechanisms of PKM2 are expected to provide more new ideas and drug targets for immunotherapy of inflammatory and autoimmune diseases, guiding drug development and disease treatment
Comparative metabolomics analysis of milk components between Italian Mediterranean buffaloes and Chinese Holstein cows based on LC-MS/MS technology
Buffalo and cow milk have a very different composition in terms of fat, protein, and total solids. For a better knowledge of such a difference, the milk metabolic profiles and characteristics of metabolites was investigated in Italian Mediterranean buffaloes and Chinese Holstein cows were investigated by liquid chromatography tandem-mass spectrometry (LC-MS/MS) in this study. Totally, 23 differential metabolites were identified to be significantly different in the milk from the two species of which 15 were up-regulated and 8 down-regulated in Italian Mediterranean buffaloes. Metabolic pathway analysis revealed that 4 metabolites (choline, acetylcholine, nicotinamide and uric acid) were significantly enriched in glycerophospholipid metabolism, nicotinate and nicotinamide metabolism, glycine, serine and threonine metabolism, as well as purine metabolism. The results provided further insights for a deep understanding of the potential metabolic mechanisms responsible for the different performance of Italian Mediterranean buffaloes’ and Chinese Holstein cows’ milk. The findings will offer new tools for the improvement and novel directions for the development of dairy industry
Dinitrogen (N) pulse emissions during freeze-thaw cycles from montane grassland soil
Short-lived pulses of soil nitrous oxide (NO) emissions during freeze-thaw periods can dominate annual cumulative NO fluxes from temperate managed and natural soils. However, the effects of freeze thaw cycles (FTCs) on dinitrogen (N) emissions, i.e., the dominant terminal product of the denitrification process, and ratios of N/NO emissions have remained largely unknown because methodological difficulties were so far hampering detailed studies. Here, we quantified both N and NO emissions of montane grassland soils exposed to three subsequent FTCs under two different soil moisture levels (40 and 80% WFPS) and under manure addition at 80% WFPS. In addition, we also quantified abundance and expression of functional genes involved in nitrification and denitrification to better understand microbial drivers of gaseous N losses. Our study shows that each freeze thaw cycle was associated with pulse emissions of both NO andN, with soil N emissions exceeding NO emissions by a factor of 5–30. Increasing soil moisture from 40 to 80% WFPS and addition of cow slurry increased the cumulative FTC N emissions by 102% and 77%, respectively. For NO, increasing soil moisture from 40 to 80% WFPS and addition of slurry increased the cumulative emissions by 147%and 42%, respectively. Denitrification gene cnorB and nosZ clade I transcript levels showed high explanatory power for NO and N emissions, thereby reflecting both N gas flux dynamics due to FTC and effects of different water availability and fertilizer addition. In agreement with several other studies for various ecosystems, we show here for mountainous grassland soils that pulse emissions of NO were observed during freeze-thaw.More importantly, this study shows that the freeze-thaw N pulse emissions strongly exceeded those of NO in magnitude, which indicates that N emissions during FTCs could represent an important N loss pathway within the grassland N mass balances. However, their actual significance needs to be assessed under field conditions using intact plant-soil systems
Quantitative analysis of water vapor budget of a persistent rainstrom event in Tongren of Guizhou Province
This paper focus on revealing the features of the water vapor transport, water vapor budget and the contribution percentage of water vapor source regions of the persistent rainstorm in Tongren from July 13th to 16th, 2014 based on precipitation observation data, ERA5 and NCEP GDAS (National Centers for Environmental Prediction, Global Data Assimilation System) reanalysis data and the HYSPLIT4 (Hybrid Single-Particle Lagrangian Integrated Trajectory Model) mode. The results show that: (1) the eastward South Asian High and coupling mechanism of high and low level jets enhanced the dynamic mechanism of convergence at low level and divergence at high level which is conducive to the convergence of water vapor in the target region to condense and then form precipitation. (2) The water vapor over the ocean was continuously transported to the rainstorm area by the water vapor channel built by the synergistic effect of the subtropical high which table controlled the south of Guizhou province, shortwave trough lay the northwest side of subtropical high, and tropical cyclone in the Indian Peninsula at 500 hPa. (3) The air particles in the rainstorm area mainly came from the Arabian Sea, the Bay of Bengal and the South China Sea at a lower height, while a few particles came from the north of Tongren to Eurasia, the Atlantic Ocean at a higher height by 120 h backward trajectory simulation. (4) The contribution percentage of water vapor source regions of the south of Tongren-South China Sea and its nearby islands and water, the east of the Indian Peninsula-the Bay of Bengal, the Arabian Sea-the west of the Indian Peninsula were 48.29%, 32.17 % and 10.47% respectively. In addition, the water vapor the north of Tongren to Eurasia and the Atlantic Ocean also contributed to the rainstorm in Tongren (9.07%). (5) 850 hPa and 700 hPa were the main water vapor contribution levels which provided nearly 3/4 of water vapor to the rainstorm area, the remaining quarter was transported by 500 hPa
EST analysis of gene expression in the tentacle of Cyanea capillata
AbstractJellyfish, Cyanea capillata, has an important position in head patterning and ion channel evolution, in addition to containing a rich source of toxins. In the present study, 2153 expressed sequence tags (ESTs) from the tentacle cDNA library of C. capillata were analyzed. The initial ESTs consisted of 198 clusters and 818 singletons, which revealed approximately 1016 unique genes in the data set. Among these sequences, we identified several genes related to head and foot patterning, voltage-dependent anion channel gene and genes related to biological activities of venom. Five kinds of proteinase inhibitor genes were found in jellyfish for the first time, and some of them were highly expressed with unknown functions
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