The Effect Of Cyperus Rotundus Ethanolic Extract On Motor Coordination In A Rat Model Of Alzheimer

Background and Objective: Alzheimer's disease (AD) is a degenerative disorder that leads to progressive cognitive decline. The memory dysfunction of AD has been associated with a cortical cholinergic deficiency and loss of cholinergic neurons of the nucleus basalis of Meynert (NBM). This study investigated the effect of ethanolic extract of Cyperus rotundu tubers (CRT) on motor activity in NBM-lesioned rat model of AD and intact rats. Materials and Methods: In this experimental study 49 Wistar rats were divided into 7 groups. For this purpose, Wistar rats received bilateral electric lesions of the NBM. The control and sham groups received distilled water while NBM-lesioned group received CRT extract for 20 days with doses of 100 and 200 mg/kg. Intact rats received CRT extract for 20 days without any surgery. The motor activity was assessed with Rotarod apparatus. Data were analyzed using one- way Anova and LSD test. Results: Use of ethanolic extract of CRT for 20 days improved motor activity in NBM-lesioned rats that received extract with a dose of 100 mg/kg. Ethanolic extract of CRT in the intact rats for 20 days significantly reduced motor activity when compared with the control group. Conclusion: The results of this study suggest that ethanolic extract of CRT is useful in NBM-induced lesion rats via inducing some changes in acetylcholine levels in the brain

Effect of lavender on blood brain barrier permeability in rats subjected to ischemia

Background and purpose: Lavender is a medicinal plant with antioxidant activity. Stroke causes long term disability and is associated with oxidative stress. The present study was conducted to evaluate the protective effect of lavender extract against blood brain barrier permeability and its possible mechanisms in an experimental model of stroke. Materials and methods: In this experimental study, 42 male Wistar rats weighing 250 to 300 g were used. The rats were divided into 6 groups (n= 7 per group). Group 1 was ischemic, groups 2 and 3 were ischemic that were given 100 and 200 mg/kg lavender extract, respectively. Group 4 were intact and groups 5 and 6 were intact groups which received lavender extract with dose of 100 and 200 mg/kg. Group 7 was also considered as the sham. Focal cerebral ischemia was induced in rats by the transient occlusion of the middle cerebral artery for 1 hr. Data were analysed with SPSS and comparison of means were compared using One Way Anova. Results: The ethanolic extract of lavender at 200 mg/kg significantly reduced the blood brain barrier permeability in rat stroke model compared with ischemic group. Conclusion: The results indicate that lavender extract has neuroprotective activity against cerebral ischemia and alleviated neurological function in rats

Upper bounds on position error of a single location estimate in wireless sensor networks

This paper studies upper bounds on the position error for a single estimate of an unknown target node position based on distance estimates in wireless sensor networks. In this study, we investigate a number of approaches to confine the target node position to bounded sets for different scenarios. Firstly, if at least one distance estimate error is positive, we derive a simple, but potentially loose upper bound, which is always valid. In addition assuming that the probability density of measurement noise is nonzero for positive values and a sufficiently large number of distance estimates are available, we propose an upper bound, which is valid with high probability. Secondly, if a reasonable lower bound on negative measurement errors is known a priori, we manipulate the distance estimates to obtain a new set with positive measurement errors. In general, we formulate bounds as nonconvex optimization problems. To solve the problems, we employ a relaxation technique and obtain semidefinite programs. We also propose a simple approach to find the bounds in closed forms. Simulation results show reasonable tightness for different bounds in various situations. © 2014 Gholami et al.; licensee Springer

Estimating the carrying capacity of tourism and the necessity of forest stands management (Case study: Darkesh forest, North Khorasan, Iran)

This study focuses on the carrying capacity estimation for Darkesh forest in Northeast Iran. Four factors were used for estimating the carrying capacity including tourist flows, size of the area, optimum space available for each tourist, and visiting time. Results showed that the physical carrying capacity was 2727 ha or 165 visitors day-1, while the real carrying capacity was 2719 ha or 132 visitors day-1. An average of 200 tourists per day visited the park during 2015, which was much higher than the estimated carrying capacity. Development of recreational uses in the study area would also affect the forest production and other benefits in long term. This study suggested that to prevent intense use of the forest area, a plan must be developed. On the other hand, the number of visitors has to be precisely calculated in order to maintain healthy forest stands and to secure the ecological benefits for future generations

Range based sensor node localization in the presence of unknown clock skews

We deal with the positioning problem based on two-way time-of-arrival (TW-TOA) measurements in asynchronous wireless sensor networks. The optimal estimator for this problem poses a difficult global optimization problem. To avoid the drawbacks in solving the optimal estimator, we use approximations and derive linear models, which facilitate efficient solutions. In particular, we employ the least squares method and solve a general trust region subproblem to find a coarse estimate. To further refine the estimate, we linearize the measurements and obtain a linear model which can be solved using regularized least squares. Simulation results illustrate that the proposed approaches asymptotically attain the Cramér-Rao lower bound. © 2013 IEEE

A distributed positioning algorithm for cooperative active and passive sensors

The problem of positioning a target node is studied for wireless sensor networks with cooperative active and passive sensors. Two-way time-of-arrival and time-difference-of-arrival measurements made by both active and passive nodes are used to estimate the position of the target node. A maximum likelihood estimator (MLE) can be employed to solve the problem. Due to the nonlinear nature of the cost function in the MLE, an iterative search might converge to local minima which often results in large estimation errors. To avoid this drawback, we instead formulate the problem of positioning as finding the intersection of a number of convex sets derived from measurements. To obtain this intersection, we apply the projection onto convex sets approach, which is robust and can be implemented in a distributed manner. Simulations are performed to compare the performance of the MLE and the proposed method. ©2010 IEEE

Hybrid TW-TOA/TDOA positioning algorithms for cooperative wireless networks

The problem of positioning an unknown target is studied for a cooperative wireless sensor network using hybrid two-way time-of-arrival and time-difference-of-arrival measurements. A maximum likelihood estimator (MLE) can be employed to solve the problem. Due to the non-linear nature of the cost function in the MLE, a numerical method, e.g., an iterative search algorithm with a good initial point, should be taken to accurately estimate the target. To avoid drawbacks in a numerical method, we instead linearize the measurements and obtain a new two-step estimator that has a closed-form solution in each step. Simulation results confirm that the proposed linear estimator can attain Cramer-Rao lower bound for sufficiently high SNR. © 2011 IEEE

Optimal Jammer Placement in Wireless Localization Systems

In this study, the optimal jammer placement problem is proposed and analyzed for wireless localization systems. In particular, the optimal location of a jammer node is obtained by maximizing the minimum of the Cramér-Rao lower bounds (CRLBs) for a number of target nodes under location related constraints for the jammer node. For scenarios with more than two target nodes, theoretical results are derived to specify conditions under which the jammer node is located as close to a certain target node as possible, or the optimal location of the jammer node is determined by two of the target nodes. Also, explicit expressions are provided for the optimal location of the jammer node in the presence of two target nodes. In addition, in the absence of distance constraints for the jammer node, it is proved, for scenarios with more than two target nodes, that the optimal jammer location lies on the convex hull formed by the locations of the target nodes and is determined by two or three of the target nodes, which have equalized CRLBs. Numerical examples are presented to provide illustrations of the theoretical results in different scenarios. © 1991-2012 IEEE