Spectral Efficiency of Multi-User Adaptive Cognitive Radio Networks

In this correspondence, the comprehensive problem of joint power, rate, and subcarrier allocation have been investigated for enhancing the spectral efficiency of multi-user orthogonal frequency-division multiple access (OFDMA) cognitive radio (CR) networks subject to satisfying total average transmission power and aggregate interference constraints. We propose novel optimal radio resource allocation (RRA) algorithms under different scenarios with deterministic and probabilistic interference violation limits based on a perfect and imperfect availability of cross-link channel state information (CSI). In particular, we propose a probabilistic approach to mitigate the total imposed interference on the primary service under imperfect cross-link CSI. A closed-form mathematical formulation of the cumulative density function (cdf) for the received signal-to-interference-plus-noise ratio (SINR) is formulated to evaluate the resultant average spectral efficiency (ASE). Dual decomposition is utilized to obtain sub-optimal solutions for the non-convex optimization problems. Through simulation results, we investigate the achievable performance and the impact of parameters uncertainty on the overall system performance. Furthermore, we present that the developed RRA algorithms can considerably improve the cognitive performance whilst abide the imposed power constraints. In particular, the performance under imperfect cross-link CSI knowledge for the proposed `probabilistic case' is compared to the conventional scenarios to show the potential gain in employing this scheme

Adaptive Modulation and Coding and Cooperative ARQ in a Cognitive Radio System

In this paper, a joint cross-layer design of adaptive modulation and coding (AMC) and cooperative automatic repeat request (C-ARQ) scheme is proposed for a secondary user in a shared-spectrum environment. First, based on the statistical descriptions of the channel, closed-form expressions of the average spectral efficiency (SE) and the average packet loss rate (PLR) are presented. Then, the cross-layer scheme is designed, with the aim of maximizing the average SE while maintaining the average PLR under a prescribed level. An optimization problem is formed, and a sub-optimal solution is found: the target packet error rates (PER) for the secondary system channels are obtained and the corresponding sub-optimal AMC rate adaptation policy is derived based on the target PERs. Finally, the average SE and the average PLR performance of the proposed scheme are presented

A Review Study on the Effect of Iranian Herbal Medicines on Opioid Withdrawal Syndrome.

Addiction is a chronic and recurring disease that recurrence phenomenon is the most important challenge in treatment of this disease. Recent experiences have shown that synthetic drugs have undesirable side effects. Recent studies on medicinal plants have shown that they might be effective in treatment of different stages of addiction with lower side effects and costs. The aim of this study was to review the effects of medicinal plants in the treatment of morphine addiction in experimental animals. In this review article, by using keywords of morphine, withdrawal, and plants or herbal medicine in databases of indexing cites, desired articles were obtained since 1994. Inclusion criteria for selecting articles were the articles related to application of medicinal plants in decreasing symptoms resulting from morphine withdrawal were selected. Results of this study on experimental studies have shown that medicinal plants such as Trachyspermum copticum L and Melissa officinalis decrease the symptoms of withdrawal syndrome in a dose-dependent. Also, medicinal plants like Avena sativa, Hypericum perforatu, Passiflora incarnate, Valeriana officinalis, Satureja hortensis L, and Mentha piperita can have effects on behavior, emotions, and other problems of addicts, decreasing withdrawal symptoms. Results of this study showed that medicinal plants can be effective in controlling deprivation, decreasing dependency creation, and possibly DETOXIFICATION: of opioid addicts

Equivalent static wind loads on snow-accreted overhead wires

The effects of structural and aerodynamic non-linearity on dynamic wind loads on overhead wires have been investigated. According to the Japanese design standards for transmission structures, wind loads on overhead wires are determined using equivalent static wind loads that can be used to estimate the maximum responses under dynamic loads. Some assumptions of linear theory are necessary to derive the equivalent static wind loads, and they have been validated only in the case of strong winds. To derive equivalent static wind loads in the case of weaker winds for snow-accreted conditions, time history response analyses of overhead wires have been performed. Because the turbulence intensity becomes higher in weaker winds, aerodynamic non-linearity causes the wind loads on the wires to become larger. Furthermore, structural non-linearity causes the tension in the wires to become greater. The contribution of wire resonance to dynamic load increases when the wind speed is low, and the gust response factor becomes greater than the value derived considering only the quasi-static response caused by wind turbulence. Taking into consideration the two major effects of aerodynamic and structural non-linearity, a modified method is proposed to enable the use of a design method based on equivalent static wind loads

Molecular Modeling Simulation Study of Interactions in Starch/Poly(acrylic acid) Blend

In this work we have studied the nature of interactions between starch and poly(acrylic acid) by using semi-empirical AM1 and PM3 methods. Theoretical computations involved the determination of optimal geometries, binding energies and vibrational frequencies of the blended polymers. Calculations are performed for four pairs of complexes of glucose (Glu) in starch and acrylic acid (mAA) in poly(acrylic acid) PAA. Based on results of calculation, the binding energies show negative values, which indicate that the interactions of glucose and acrylic acid are favorable at the lower energy. This means that the interactions of starch and PAA are stable. Vibrational frequency analysis of hydroxyl OH and carboxyl C=O groups of the 1Glu–1mAA, 1Glu–2mAA and 1Glu–3mAA complexes with single hydrogen bond showed that the stretching of these groups shifts to a lower wave number due to the formation of hydrogen bonds. Keywords:Polymer blends, AM1, PM3

A review on most important herbal and synthetic antihelmintic drugs

Parasites and parasitic diseases are widely spread in the world. Their adverse effects on health and social economic society cause tremendous public health problems. Parasitic infections in different ways (water, soil, food and vegetables) can affect humans and induce other complications such as gastrointestinal disorders, malnutrition, anemia and allergies and sometimes even life threatening. Medicinal plants are being widely used, either as a single drug or in combination with synthetic drugs. These medicinal plants are considered as a valuable source of unique natural products and drugs for development of medicines against various disorders and diseases. In this article the recently published papers about medicinal plants and parasites were reviewed, using scientific sites such as Medline, PubMed and Google Scholar. The used terms included: herbal medicine, medicinal plants, and antihelmintic drugs, antinematoda, anticestoda, antitrematoda. From the above collected literature it might be concluded that these plants are promising potential sources for preparation of new drugs or for pharmacological and therapeutic applications

Volatile Composition and Outgassing in C/2018 Y1 (IWAMOTO): Extending Detection Limits for High-Resolution IR Cometary Spectroscopy at the NASA-IRTF

We used iSHELL, the powerful high-resolution ( /~ 40,000) cross-dispersed IR spectrograph at the NASA-IRTF to measure the native ice composition and outgassing of moderately bright, long-period comet C/2018 Y1 (Iwamoto) (hereafter Y1) within weeks of its discovery. We measured production rates for H2O, and production rates and abundance ratios relative to H2O for eight trace molecules, including the most complete measure of cometary CH4 achieved to date. Compared with mean abundances measured among comets, our study revealed enriched CH3OH and C2H6 yet depleted CO and C2H2, perhaps indicating highly efficient H- atom addition on interstellar grains prior to their incorporation into the nucleus. The combined high spectral resolving power and broad spectral coverage of iSHELL allowed characterizing cometary composition using only three instrument settings, and its long-slit coverage allowed comparing the spatial distributions of molecular emissions and dust continuum

Comment on “Chemically Mediated Behavior of Recruiting Corals and Fishes: A Tipping Point That May Limit Reef Recovery”

Dixson et al. (2014) report that coral larvae navigate towards chemical cues associated with healthy reefs and avoid cues from degraded reefs. However, the swimming capabilities of coral larvae and well-established patterns of recruitment and reef hydrodynamics indicate that coral larvae will not be able to use these cues to recruit to healthy reefs. Perfuming degraded reefs, as suggested by Dixson et al (2014), will not enhance recovery rather it will distract from the difficult task of reducing fishing effort and improving water quality