Wormhole solutions with a polynomial equation-of-state and minimal violation of the null energy condition

This paper discusses wormholes supported by general equation-of-state , resulting in a significant combination of the linear equation-of-state and some other models. Wormhole with a quadratic equation-of-state is studied as a particular example. It is shown that the violation of null energy condition is restricted to some regions in the vicinity of the throat. The combination of barotropic and polytropic equation-of-state has been studied. We consider fluid near the wormhole throat in an exotic regime which at some $r=r_{1}$, the exotic regime is connected to a distribution of asymptotically dark energy regime with $-1<\omega<-1/3$. We have presented wormhole solutions with small amount of exotic matter. We have shown that using different forms of equation-of-state has a considerable effect on the minimizing violation of the null energy condition. The effect of many parameters such as redshift as detected by a distant observer and energy density at the throat on the $r_1$ is investigated. The solutions are asymptotically flat and compatible with presently available observational data at the large cosmic scale.Comment: 12 pages, 13 figure

On the structure of sequentially Cohen--Macaulay bigraded modules

Let $K$ be a field and $S=K[x_1,\ldots,x_m, y_1,\ldots,y_n]$ be the standard bigraded polynomial ring over $K$. In this paper, we explicitly describe the structure of finitely generated bigraded "sequentially Cohen--Macaulay" $S$-modules with respect to $Q=(y_1,\ldots,y_n)$. Next, we give a characterization of sequentially Cohen--Macaulay modules with respect to $Q$ in terms of local cohomology modules. Cohen--Macaulay modules that are sequentially Cohen--Macaulay with respect to $Q$ are considered

Worst-Case Robust Distributed Power Allocation in Shared Unlicensed Spectrum

This paper considers non-cooperative and fully-distributed power-allocation for selfish transmitter-receiver pairs in shared unlicensed spectrum when normalized-interference to each receiver is uncertain. We model each uncertain parameter by the sum of its nominal (estimated) value and a bounded additive error in a convex set, and show that the allocated power always converges to its equilibrium, called robust Nash equilibrium (RNE). In the case of a bounded and symmetric uncertainty region, we show that the power allocation problem for each user is simplified, and can be solved in a distributed manner. We derive the conditions for RNE's uniqueness and for convergence of the distributed algorithm; and show that the total throughput (social utility) is less than that at NE when RNE is unique. We also show that for multiple RNEs, the social utility may be higher at a RNE as compared to that at the corresponding NE, and demonstrate that this is caused by users' orthogonal utilization of bandwidth at RNE. Simulations confirm our analysis

Quercetin improved spatial memory dysfunctions in rat model of intracerebroventricular streptozotocin-induced sporadic Alzheimer’sdisease

Background: Alzheimer’s disease (AD) is one of the most common neurodegenerative syndromes characterized by a progressive decline in the spatial memory. There are convincing evidences on the neuroprotective effects of flavonoids against AD. Aims and Objective: To determine the effect of quercetin on the acquisition and retention of spatial memory in a rat model of AD. Materials and Methods: Twenty-four male Wistar rats were divided into four groups (six in each): group I: control rats receiving intracerebroventricular (ICV) injection of normal saline, group II: rats induced AD by ICV injection of streptozotocin (STZ; 3 mg/kg bilaterally; twice, on days 1 and 3), and groups III and IV: ICV-STZ AD rats treated intraperitoneally (IP) with 40 and 80 mg/kg/day quercetin, respectively, over a period of 12 days. Then, the rats were trained with four trials per day for five consecutive days in the Morris water maze (MWM). On the sixth day, the memory retention was evaluated. Result: The ICV-STZ AD groups showed a significant impairment in the acquisition and retrieval of spatial memory when compared with the control group (P < 0.001). In the AD groups, the escape latency during the training trials showed a significant decrease (P < 0.001). Meanwhile, during the MWM task, theseratsspentmoretimeinthetargetquadrant in probe trials when compared with the controls. Conclusion: Quercetin acted as a spatial memory enhancer in ICV-STZ–induced AD rats. Hence, this flavonoid can be considered potentially as a promising agent for developing prophylactic and therapeutic neuroprotection. This neuroprotective effect of quercetin may be attributed to its antioxidant and scavenging properties. © 2015 Hamid Sepehri

Comparison of gabapentin and ketotifen in treatment of uremic pruritus in hemodialysis patients

Objectives: Uremic pruritus is a common problem in hemodialysis patients. Several treatments have been used for decreasing itching in these patients. Gabapentin and ketotifen are two drugs used for treating uremic patients.The aim of this study was to compare gabapentin and ketotifen in treatment of uremic pruritus in hemodialysis patients. Methods: In this double-blind randomized clinical trial, 52 hemodialysis patients with uremic pruritus referred to 5azarTeaching Hospital in Gorgan in 2013 were studied. Patients were randomly assigned to two groups of 26 subjects (groups G and K). In group G, patients treated with gabapentin capsules 100 mg daily for 2 weeks, and in Group K, patients treated with ketotifen 1 mg twice daily for 2 weeks. Before and at the end of study, pruritus severity was determined based on Shiratori›s severity scores. Collected data were analyzed by SPSS-21 statistical software. Results: There was no significant different between two groups in the age and sex. After two weeks of treatment, severity of pruritus was significantly reduced in both groups (88.4 in group G vs. 76.9 in group K). Gabapentin compared with ketotifen had a better effect on improving itching in the age group of 30-60 years and in males. 5 patients (19.2) in both groups suffered from drowsiness and dizziness, but no serious side effects were observed. Conclusions: The results showed that gabapentin and ketotifen significantly improved pruritus in hemodialysis patients, and no significant difference was observed between two groups. © 2016, Professional Medical Publications. All rights reserved

Signed graphs cospectral with the path

A signed graph $\Gamma$ is said to be determined by its spectrum if every signed graph with the same spectrum as $\Gamma$ is switching isomorphic with $\Gamma$. Here it is proved that the path $P_n$, interpreted as a signed graph, is determined by its spectrum if and only if $n\equiv 0, 1$, or 2 (mod 4), unless $n\in\{8, 13, 14, 17, 29\}$, or $n=3$

Traversable wormholes satisfying energy conditions in f(Q)f(Q) gravity

In this article, a new family of asymptotically flat wormhole solutions in the context of symmetric teleparallel gravity, i.e., $f(Q)$ theory of gravity, are presented. Considering a power-law shape function and some different forms for $f(Q)$ function, we show that a wide variety of wormhole solutions for which the matter fields satisfy some energy conditions, are accessible. We explore that the presence of $f(Q)$ gravity will be enough to sustain a traversable wormhole without exotic matter. The influence of free parameters in shape function and $f(Q)$ models on the energy conditions is investigated. The equation of state and boundary conditions are analyzed.Comment: 12 pages, 20 figure