Optimal Distributed Resource Allocation for Decode-and-Forward Relay Networks

This paper presents a distributed resource allocation algorithm to jointly optimize the power allocation, channel allocation and relay selection for decode-and-forward (DF) relay networks with a large number of sources, relays, and destinations. The well-known dual decomposition technique cannot directly be applied to resolve this problem, because the achievable data rate of DF relaying is not strictly concave, and thus the local resource allocation subproblem may have non-unique solutions. We resolve this non-strict concavity problem by using the idea of the proximal point method, which adds quadratic terms to make the objective function strictly concave. However, the proximal solution adds an extra layer of iterations over typical duality based approaches, which can significantly slow down the speed of convergence. To address this key weakness, we devise a fast algorithm without the need for this additional layer of iterations, which converges to the optimal solution. Our algorithm only needs local information exchange, and can easily adapt to variations of network size and topology. We prove that our distributed resource allocation algorithm converges to the optimal solution. A channel resource adjustment method is further developed to provide more channel resources to the bottleneck links and realize traffic load balance. Numerical results are provided to illustrate the benefits of our algorithm

2D film of carbon nanofibers elastically astricted MnO microparticles: A flexible binder-free anode for highly reversible lithium ion storage

MnO as anode materials has received particular interest owing to its high specific capacity, abundant resources and low cost. However, it is still a serious problem that large volume change (>170%) during the lithiation/delithiation processes results in poor rate capability and fast capacity decay. With homogenous crystals of MnO grown in the network of carbon nanofibers(CNF)，binding effect of CNFs can effectively weaken the volume change of MnO during cycles. In this work, CNF/MnO flexible electrode for lithium-ion batteries is designed and synthesized. The carbon nanofibers play the roles of conductive channel and elastically astricting MnO particles during lithiation/delithiation. CNF/MnO as binder-free anode delivers specific capacity of 983.8 mAh g−1 after 100th cycle at a current density of 0.2 A g−1, and 600 mAh g−1 at 1 A g−1 which are much better than those of pure MnO and pure CNF. The ex-situ FESEM images of CNF/MnO clearly show the relative volume change of MnO/CNF as anode under various discharging and charging time. CNFs can elastically buffer the volume change of MnO during charging/discharging cycles. This work presents a facile and scalable approach for synthesizing a novel flexible binder-free anode of CNF/MnO for potential application in highly reversible lithium storage devices

New Superhard Carbon Phases Between Graphite and Diamond

Two new carbon allotropes (H-carbon and S-carbon) are proposed, as possible candidates for the intermediate superhard phases between graphite and diamond obtained in the process of cold compressing graphite, based on the results of first-principles calculations. Both H-carbon and S-carbon are more stable than previously proposed M-carbon and W-carbon and their bulk modulus are comparable to that of diamond. H-carbon is an indirect-band-gap semiconductor with a gap of 4.459 eV and S-carbon is a direct-band-gap semiconductor with a gap of 4.343 eV. The transition pressure from cold compressing graphite is 10.08 GPa and 5.93 Gpa for H-carbon and S-carbon, respectively, which is in consistent with the recent experimental report.Comment: 5pages,4figures,submitted to Phys.Rev.Lett on 18Jan12, transfer to Phys.Rev.B on 25Mar12; Solid State Communications(2012), http://dx.doi.org/10.1016/j.ssc.2012.05.02

Breast-conserving surgery without axillary surgery and radiation versus mastectomy plus axillary dissection in elderly breast cancer patients: A retrospective study

BackgroundThe high relative mortality rate in elderly breast cancer patients is most likely the result of comorbidities rather than the tumor load. Foregoing axillary lymph node dissection or omitting radiotherapy after breast-conserving surgery (BCS) does not affect the prognosis of elderly breast cancer patients. We sought to assess the safety of breast-conserving surgery without axillary lymph node dissection as well as breast and axillary radiotherapy (BCSNR) in elderly patients with early-stage breast cancer.MethodsWe retrospectively included 541 consecutive breast cancer patients aged over 70 years with clinically negative axillary lymph nodes in one clinical center. Of these patients, 181 underwent mastectomy plus axillary lymph node dissection (MALND) with negative axillary cleaning and 360 underwent BCSNR.ResultsAfter a median follow-up of 5 years, there was no significant difference between the BCSNR and MALND groups in either distant recurrence-free survival (DRFS) (p=0.990) or breast cancer-specific survival (p=0.076). Ipsilateral axillary disease was found in 11 (3.1%) patients in the BCSNR group and 3 (1.7%) patients in the MALND group; this difference was not significant (p=0.334). We did not observe a significant difference in distant recurrence between the groups (p=0.574), with 25 (6.9%) patients in the BCSNR group experiencing distant recurrence compared to 15 (8.3%) patients in the MALND group. Our findings did show a significant difference in ipsilateral breast cancer recurrence (IBTR), with 31 (8.6%) patients in the BCSNR group experiencing IBTR compared to only 2 (1.1%) patients in the MALND group (p=0.003).ConclusionBCSNR is a safe treatment option for elderly breast cancer patients with clinically negative axillary lymph nodes

The Emergence of Chromosomally Located blaCTX-M-55 in Salmonella From Foodborne Animals in China

The emergence and increase in prevalence of resistance to cephalosporins amongst isolates of Salmonella from food animals imposes a public health threat. The aim of the present study was to investigate the prevalence and characteristics of CTX-M-producing Salmonella isolates from raw meat and food animals. 27 of 152 (17.76%) Salmonella isolates were ESBL-positive including 21/70 (30%) from food animals and 6/82 (7.32%) from raw meat. CTX-M-55 was the most prevalent ESBL type observed (12/27, 44.44%). 7 of 12 CTX-M-55-positive Salmonella isolates were Salmonella Indiana, 2 were Salmonella Typhimurium, 2 were Salmonella Chester, and the remaining isolate was not typeable. Eight CTX-M-55-positive Salmonella isolates were highly resistant to fluoroquinolones (MICCIP = 64 ug/mL) and co-harbored aac(6')-Ib-cr and oqxAB. Most of the CTX-M-55 positive isolates (11/12) carried blaCTX-M-55 genes on the chromosome, with the remaining isolate carrying this gene on a transferable 280 kb IncHI2 plasmid. A chromosomal blaCTX-M-55 gene from one isolate transferred onto a 250 kb IncHI2 plasmid which was subsequently conjugated into recipient strain J53. PFGE and MLST profiles showed a wide range of strain types were carrying blaCTX-M-55. Our study demonstrates the emergence and prevalence of foodborne Salmonella harboring a chromosomally located blaCTX-M-55 in China. The co-existence of PMQR genes with blaCTX-M-55 in Salmonella isolates suggests co-selection and dissemination of resistance to both fluoroquinolones and cephalosporins in Salmonella via the food chain in China represents a public health concern

Human migration activities drive the fluctuation of ARGs : Case study of landfills in Nanjing, eastern China

Landfills are perfect sites to study the effect of human migration on fluctuation of antibiotic resistance genes (ARGs) as they are the final destination of municipal waste. For example, large-scale human migration during the holidays is often accompanied by changes in waste dumping having potential effects on ARG abundance. Three landfills were selected to examine fluctuation in the abundance of fifteen ARGs and Intl1 genes for 14 months in Nanjing, eastern China. Mass human migration, the amount of dumped waste and temperature exerted the most significant effects on bimonthly fluctuations of ARG levels in landfill sites. As a middle-sized cosmopolitan city in China, millions of college students and workers migrate during holidays, contributing to the dramatic increases in waste production and fluctuation in ARG abundances. In line with this, mass migration explained most of the variation in waste dumping. The waste dumping also affected the bioaccessibility of mixed-compound pollutants that further positively impacted the level of ARGs. The influence of various bioaccessible compounds on ARG abundance followed the order: antibiotics>nutrients>metals>organic pollutants. Concentrations of bioaccessible compounds were more strongly correlated with ARG levels compared to total compound concentrations. Improved waste classification and management strategies could thus help to decrease the amount of bioaccessible pollutants leading to more effective control for urban ARG dissemination

Ras-induced Epigenetic Inactivation of the RRAD ( Ras-related Associated with Diabetes) Gene Promotes Glucose Uptake in a Human Ovarian Cancer Model

Background: Increased glucose uptake is essential for carcinogenesis. Results: Ras(V12)-induced epigenetic inactivation of RRAD promotes glucose uptake and tumor formation. Conclusion: RRAD might act as a functional tumor suppressor by inhibiting glucose uptake. Significance: Down-regulation of RRAD in tumor tissues might be associated with the Warburg effect. RRAD (Ras-related associated with diabetes) is a small Ras-related GTPase that is frequently inactivated by DNA methylation of the CpG island in its promoter region in cancer tissues. However, the role of the methylation-induced RRAD inactivation in tumorigenesis remains unclear. In this study, the Ras-regulated transcriptome and epigenome were profiled by comparing T29H (a Ras(V12)-transformed human ovarian epithelial cell line) with T29 (an immortalized but non-transformed cell line) through reduced representation bisulfite sequencing and digital gene expression. We found that Ras(V12)-mediated oncogenic transformation was accompanied by RRAD promoter hypermethylation and a concomitant loss of RRAD expression. In addition, we found that the RRAD promoter was hypermethylated, and its transcription was reduced in ovarian cancer versus normal ovarian tissues. Treatment with the DNA methyltransferase inhibitor 5-aza-2-deoxycytidine resulted in demethylation in the RRAD promoter and restored RRAD expression in T29H cells. Additionally, treatment with farnesyltransferase inhibitor FTI277 resulted in restored RRAD expression and inhibited DNA methytransferase expression and activity in T29H cells. By employing knockdown and overexpression techniques in T29 and T29H, respectively, we found that RRAD inhibited glucose uptake and lactate production by repressing the expression of glucose transporters. Finally, RRAD overexpression in T29H cells inhibited tumor formation in nude mice, suggesting that RRAD is a tumor suppressor gene. Our results indicate that Ras(V12)-mediated oncogenic transformation induces RRAD epigenetic inactivation, which in turn promotes glucose uptake and may contribute to ovarian cancer tumorigenesis

Physical Properties of H II Regions in M51 from Spectroscopic Observations

M51 and NGC 5195 is an interacting system that can be explored in great details with ground-based telescopes. The H II regions in M51 were observed using the 2.16 m telescope of the National Astronomical Observatories of the Chinese Academy of Sciences and the 6.5 m Multiple Mirror Telescope with spatial resolution of less than $\sim100$ pc. We obtain a total of 113 spectra across the galaxy and combine the literature data of Croxall et al. to derive a series of physical properties, including the gas-phase extinction, stellar population age, star formation rate (SFR) surface density, and oxygen abundance. The spatial distributions and radial profiles of these properties are investigated in order to study the characteristics of M51 and the clues to the formation and evolution of this galaxy. M51 presents a mild radial extinction gradient. The lower gas-phase extinction in the north spiral arms compared to the south arms are possibly caused by the past encounters with the companion galaxy of NGC 5195. A number of H II regions have the stellar age between 50 and 500 Myr, consistent with the recent interaction history by simulations in the literatures. The SFR surface density presents a mild radial gradient, which is ubiquitous in spiral galaxies. There is a negative metallicity gradient of $-0.08$ dex $R_{e}^{-1}$ in the disk region, which is also commonly found in many spiral galaxies. It is supported by the "inside-out" scenario of galaxy formation. We find a positive abundance gradient of 0.26 dex $R_{e}^{-1}$ in the inner region. There are possible reasons causing the positive gradient, including the freezing of the chemical enrichment due to the star-forming quenching in the bulge and the gas infall and dilution due to the pseudobulge growth and/or galactic interaction.Comment: 20 pages, 8 figures, 1 appendix, Accepted for publication in PASP. Comments and suggestions are welcom