Joint Spectrum Sensing and Resource Allocation for OFDM-based Transmission with a Cognitive Relay

In this paper, we investigate the joint spectrum sensing and resource allocation problem to maximize throughput capacity of an OFDM-based cognitive radio link with a cognitive relay. By applying a cognitive relay that uses decode and forward (D&F), we achieve more reliable communications, generating less interference (by needing less transmit power) and more diversity gain. In order to account for imperfections in spectrum sensing, the proposed schemes jointly modify energy detector thresholds and allocates transmit powers to all cognitive radio (CR) subcarriers, while simultaneously assigning subcarrier pairs for secondary users (SU) and the cognitive relay. This problem is cast as a constrained optimization problem with constraints on (1) interference introduced by the SU and the cognitive relay to the PUs; (2) miss-detection and false alarm probabilities and (3) subcarrier pairing for transmission on the SU transmitter and the cognitive relay and (4) minimum Quality of Service (QoS) for each CR subcarrier. We propose one optimal and two sub-optimal schemes all of which are compared to other schemes in the literature. Simulation results show that the proposed schemes achieve significantly higher throughput than other schemes in the literature for different relay situations.Comment: EAI Endorsed Transactions on Wireless Spectrum 14(1): e4 Published 13th Apr 201

Characteristic structural features of indolicidin: effects of the cis-trans isomerism on its conformation

Indolicidin is an antimicrobial peptide showing a broad spectrum of antibacterial and antifungal activities, and according to the cis-trans isomerism of three Xaa-Pro peptide bonds, eight different stereoisomers could be distinguished for this peptide. As the cis-trans isomerism about the Xaa-Pro peptide bonds was not considered in previous studies, the structural features of distinct stereoisomeric forms were not characterized in detail, so far. In this theoretical study, the influences of cis-trans isomerism on the conformation of indolicidin were investigated, as well as the typical structural properties of each stereoisomer were determined, focusing on the secondary structures and intramolecular interactions. Based on the results derived from the molecular dynamics simulations, it could be concluded that the eight different stereoisomeric forms of indolicidin adopted characteristic conformational features. Nevertheless, the appearance of various turn structures and intramolecular interactions proved to be dependent on the cis or trans nature of Xaa-Pro peptide bonds, indicating the relevant role of Pro amino acids in determining the three-dimensional structure of this peptide

Awareness on Entrepreneurial Orientation Among Management Students in Vellore

Purpose: Thus, the objective of this study was to analyze, by means of multivariate techniques, an instrument whose function is to measure the learning of teaching Entrepreneurship, verifying the change in the entrepreneurial profile between participants and non-participants of the entrepreneurial formation process. The research was carried out among university students of the Business Administration course, Vellore.   Theoretical Framework: Entrepreneurship is a socio-economic phenomenon that has been valued for its influence on the growth and development of regional and national economies. The main agent promoting this phenomenon is the entrepreneur; a subject endowed with multiple characteristics who act in a dynamic way and is focused on reaping results, the fruits of their personal efforts. The insertion and search for enterprising subjects in different societies have been noticeable in public, economic and educational programs and policies. Entrepreneurial education is highlighted as one of the most efficient ways to disseminate culture and train new entrepreneurs. From this perspective, the teaching of Entrepreneurship stands out as a resource used for the formation of new entrepreneurs.   Design/Methodology/Approach: The present study aims to analyze the entrepreneurial intention of students from four Institutions in Vellore, relating it to entrepreneurial self-efficacy and academic self-efficacy, and to try to understand which factors influence it. The sample of this study consists of 290 students from four Institutions in Vellore, of which 114 (39.3%) are male and 176 (60.7%) are female.   Findings: Regarding the degree of importance that students attribute to the Institution support structures for the creation of a company, there is a statistically significant difference, in which the GTEC students stand out, who are the ones who attach the most importance to ”Spaces and equipment for starting the business". With regard to the remaining questions, there are no statistically significant differences between the mean values of the answers given depending on the Institution.   Research, Practical/ & Social Implications: In the analysis of the differences between Institutions, it was verified the existence of statistically significant differences in the questions related to the desire to create their own company and to have a concrete business idea to create, in which SPIM showed a higher average in relation to the other three Institutions. Regarding the other two research questions, “I consider myself capable of creating a company”, and “I am able to work on my own”, there were no statistically significant differences between the four Institutions.   Originality/Value: The present study adds value among the management students with regard to the awareness on entrepreneurship which leads to the country’ economic development

Schiff bases derived from 4-amino-N-substituted benzenesulfonamide: synthesis, spectral characterisation and MIC evaluation

ABSTRACT. The present study is aimed to synthesise Schiff bases from sulfathiazole/ sulfamethoxazole/ sulfadimidine with 2-hydroxybenzaldehyde. The synthesized Schiff bases were characterized by analytical data, IR, 1H-NMR, 13C-NMR, UV-Vis spectra, mass spectra and screened for antibacterial activity against gram positive bacteria Staphylococcus aureus and gram negative bacteria Salmonella typhiand antifungal activity against Candida albicans and Mucor by disc diffusion method. Zone of inhibition indicated that the Schiff base possessed highly potent antimicrobial activity when compared to sulpha drugs.                     KEY WORDS: 4-Amino-N-(1,3-thiazol-2-yl)benzenesulfonamide, 4-amino-N-(5-methylisoxazol-3-yl)-benzenesulfonamide, 4-amino-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide, 2-hydroxybenzaldehyde, antimicrobial activity   Bull. Chem. Soc. Ethiop. 2021, 35(2), 435-448.  DOI: https://dx.doi.org/10.4314/bcse.v35i2.1

Interaction of indolicidin, a 13-residue peptide rich in tryptophan and proline and its analogues with model membranes

Indolicidin is a 13-residue broad-spectrum antibacterial peptide isolated from bovine neutrophils. The primary structure of the peptide ILPWKWPWWPWRR-amide (IL) reveals an unusually high percentage of tryptophan residues. IL and its analogues where proline residues have been replaced by alanine (ILA) and trp replaced by phe (ILF) show comparable antibacterial activitieso While IL and ILA are haemolytic, ILF does not have this property. Since aromatic residues would strongly favour partitioning of the peptide into the lipid bilayer interface, the biological activities of IL and its analogues could conceivably arise due perturbation of the lipid bilayer of membranes. We have therefore investigated the interaction of IL and its analogues with lipid vesicles. Peptides IL and ILA bind to lipid vesicles composed of phosphatidylcholine and phosphatidylethanol amine: phosphatidyl glycerol: cardiolipin. The position of λmax and I- quenching experiments suggest that the trp residues are localized at the membrane interface and not associated with the hydrophobic core of the lipid bilayer in both the peptides. Hence, membrane permeabilization is likely to occur due to deformation of the membrane surface rather than formation of transmembrane channels by indolicidin and its analogues. Peptides ILA, IL and ILF cause the release of entrapped carboxyfluorescein from phosphatidyl choline vesicles. The peptide-lipid ratios indicate that ILF is less effective than IL and ILA in permeabilizing lipid vesicles, correlating with their haemolytic activities

INFLUENCE OF CANCER SEVERITY AND FUNCTIONAL STATUS OF CANCER ON CARDIAC PARASYMPATHETIC INDICATORS

 Objective: To investigate the influence of cancer severity and functional status of cancer patients on cardiac parasympathetic indicators. Methods: A total of 267 patients with a fresh clinical diagnosis of solid malignant tumor not yet put on cancer therapy and 250 controls matched for age, sex of study subjects were included. Severity of cancer was defined based on the American Joint Committee on Cancer staging. Accordingly, study subjects were subdivided into early stage (Stage I and II combined) and advanced stage (Stage III and IV combined). In cancer patients, the Eastern Cooperative Oncology Group (ECOG) performance score and the Faces Pain Scale score (FPS) was noted. Two indicators of vagal function, expiratory:inspiratory ratio (E:I ratio) and root mean square of successive N-N interval difference (r-MSSD) were included. E:I ratio during deep breathing at six respiratory cycles/minute and r-MSSD at rest was obtained from 1 minute lead II electrocardiogram. Data were analyzed by applying suitable statistical tests. p≤0.05 was considered significant. Results: R-MSSD and E:I ratio was significantly reduced in the early and advanced stage of cancer compared to controls (p≤0.0001). r-MSSD and E:I ratio was significantly reduced in advanced stage compared to the early stage of cancer (p≤0.0001). r-MSSD and E:I ratio was significantly different in subgroups of stages of cancer and controls (p≤0.0001). In cancer patients, r-MSSD was negatively correlated with ECOG and FPS score (p≤0.0278, p≤0.0100). Conclusion: Severity of cancer affects vagal function. However, r-MSSD alone was associated with functional status (ECOG, FPS) of cancer patients