Enhancing the Performance of Low Priority SUs Using Reserved Channels in CRN

Cognitive radio networks (CRNs) are considered a promising solution for spectrum resources scarcity and efficient channel utilization. In this letter, multi-dimensional analytical Markov model based on reservation channel access scheme and channel aggregation method is proposed to enhance spectrum utilization, capacity of low priority secondary users (SUs) and reducing handoff probability of SUs. Moreover, the proposed method improves the performance of high priority SUs by providing the capability to resume the connection after dropping. The numerical results indicate that the modified reservation access model can enhance the performance of SUs compared to the traditional basic random access model

PRIMING OPTIMISM: THE AUTOMATICITY OF HEALTH RISK PERCEPTIONS

Communication initiatives frequently are used to inform people about various risks in an attempt to improve their decision making and behavior. People, however, do not readily accept personal risk information, often underestimating their susceptibility to and the severity of the risks. This dissertation draws on psychological theory and research to explain why people underestimate their risks. Three experiments were designed to test whether people have an automatic tendency to underestimate self-relevant risks - the default option that occurs without conscious awareness of underestimation of health risks as a bias and of self-schema activation as a source of this bias and is likely to occur when people are mentally taxed. Rationale for the theoretical propositions advanced here is derived from research documenting that health risk information is (a) processed as self-relevant, (b) inconsistent with the positivity bias and self-threatening, and that (c) the activation of the self-schema is automatic. Experiment 1 tested the hypothesis that people underestimate their likelihood of experiencing negative health conditions and overestimate their likelihood of experiencing positive ones. Experiment 2 examined whether underestimation of health risks is an efficient process, one that occurs when people are mentally taxed. Finally, Experiment 3 tested the effects of health risk controllability and psychological reactance on health risk perceptions. All three experiments relied on priming to activate the self-schema and measured the effects of this activation on reaction time, an implicit measure of risk perceptions. Several individual difference variables (e.g., self efficacy) and health risk characteristics (e.g., prevalence) that influence risk perceptions were controlled for. Results show that people automatically underestimate their health risks, that is, without awareness, intention, or effort. The studies provided conclusive evidence of (a) underestimation of susceptibility to negative health conditions and overestimation of susceptibility to positive ones and (b) efficiency of underestimation of health risks. Results regarding self-schema activation as a source of underestimation of risks were not as conclusive. Individual difference variables did not affect implicit measures of risk perceptions. Health risk characteristics, on the other hand, influenced risk perceptions. The experiments showed an inverted relationship between susceptibility and severity dimensions of health risk perceptions.Doctor of Philosoph

Incidence of Yersinia enterocolitica in raw farm and market milk sample

Objectives: This study was applied to investigate the incidence of Yersinia enterocolitica in raw farm and market milk and studying the quality drawbacks which might happen in milk as a result of its existence.Design: Observation study.Samples: One hundred raw milk samples.Procedures: Fifty bulk tank milk (BTM), 25 individual milk & 25 market milk samples were collected from various dairy farms and supermarkets in Dakahlia Governorate, Egypt. The quality assessment of the samples began with evaluating the milk physical characteristics including color, odor, pH and the titratable acidity that reflected the hygienic quality of milk production on farm levels. Then the samples were directed for biochemical and microbiological examination with subsequent PCR approach.Results: The range of titratable acidity started from 0.11 – 0.20 % lactic acid with a mean value of 0.15 ± 0.004. While for microbiological examination of the samples by using the conventional methods of cultivation on (CIN) agar medium, 33 presumptive Yersinia isolates were recovered and intended for biochemical tests among which 5 out of these latter isolates were confirmed as Y. enterocolitica by applying PCR, through detecting the presence of 16srRNA gene. Also, this study evaluates not only the public health of consumers concerning the titratable acidity of the examined samples, but also the economic importance of these retailed samples in supermarkets; as Y. enterocolitica could be transmitted through the consumption of raw milk. Conclusion and Clinical Relevance: The Y. enterocolitica incidence was 29% in the examined raw farm and market milk samples

Notice of correction

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Fault ride-through enhancement of fixed speed wind turbine using bridge-type fault current limiter

AbstractThe interaction between wind energy turbines and the grid results in two main problems, increasing the short-circuit level and reducing the Fault Ride-Through (FRT) capability during faults. The objective of this paper is to solve these problems, for fixed speed Wind Energy Systems (WECS), utilizing the bridge-type Fault Current Limiter (FCL) with a discharging resistor. A simple cascaded control system is proposed for the FCL to regulate the terminal voltage of the generator and limit the current. The system is simulated on PSCAD/EMTDC software to evaluate the dynamic performance of the proposed WECS compensated by FCL. The simulation results show the potentials of the FCL as a simple and effective method for solving grid interconnection problems of WECS

Isolation, purification and characterization of phytase from Bacillus subtilis MJA

In this study, three strains of bacteria were isolated from soil. Among the three isolated strains, one was identified morphologically and confirmed by the molecular techniques as Bacillus subtilis MJA with high phytase activity. The phytase-producing bacteria were isolated using phytate screening agar media (PSM) with only 1.5% glucose and 0.5% sodium phytate as only source for carbon. In order to optimize the phytase production by B. subtilis MJA, different factors were studied. A combination of 0.5% glucose and 0.5% sucrose showed to be the best carbon source. Also, malt extract used as a source of nitrogen gave the highest phytase production. Also, the maximum phytase production was detected after incubation for four days (720 U/ml) at an optimum pH value of 7. The produced phytase was purified through various chromatographic techniques. The estimated enzyme molecular mass was about 38 kDa and the phytase had an optimal temperature and pH of 37°C and 5 to 6, respectively. On the other hand, studying the enzyme stability showed that enzyme was stable at low temperature, and had good pH stability by retaining 80% of its initial activity over a wide range of pH from 2 to 8. Kinetic values of Vmax and Km for the purified enzyme were 510 U/mg and 0.485 mM, respectively. The phytase activity was affected by different divalent metal ions. Cations such as Cu2+ or Fe2+ showed an inhibition effect on the phytase activity and the effect was in a dose dependent manner while, cations such as Mg2+ or Ca2+ showed an increase in the phytase activity. On the other hand, among different matricesused to immobilize the cells for phytase production, agar-agar matrix indicated a promising immobilization matrix used for phytase production by B. subtilis MJA.Keywords: Phytase, microbial sources, optimization, purification, characterization, immobilizationAfrican Journal of BiotechnologyVol. 12(20), pp. 2957-296

Optimization, economization and characterization of cellulase produced by marine Streptomyces ruber

Cellulase is a very important enzyme due to its great industrial applications. Six marine strains of actinomycetes were screened for their carboxymethyl cellulase (CMCase) productivity. Streptomyces ruber was chosen to be the best producing strain. The highest enzyme production (25.6 U/ml) was detected at pH 6 and 40°C after 7 days of incubation. Plackett-Burman design was applied to optimize the different culture conditions affecting enzyme production. Results showed that a high concentration of KH2PO4, and a low concentration of MgSO4 had a significant effect on enzyme production. Rice straw was used as a low cost source of cellulose. It was found that 30 g/l rice straw was the suitable concentration for maximum enzyme production. Partial purification of cellulase enzyme using an anionexchange chromatography resulted in the detection of two different types of CMCases, type I and II, with specific activity of 4239.697 and 846.752 U/mg, respectively. Moreover, estimation of their molecular weight revealed 27.0 kDa for cellulase type I and 24.0 kDa for cellulase type II. It could be concluded that S. ruber is a powerful cellulase producer strain under our tested experimental conditions.Key words: Cellulase production, Streptomyces ruber, Plackett-Burman design, rice straw, enzyme characterization

Reliability of candida skin test in the evaluation of T-cell function in infancy

Background: Both standardized and non-standardized candida skin tests are used in clinical practice for functional in-vivo assessment of cellular immunity with variable results and are considered not reliable under the age of 1 year. We sought to investigate the reliability of using manually prepared candida intradermal test in the evaluation of T cell function in infants during their second year of life.Methods: Twenty-five healthy infants were tested with manually prepared intradermal candida test. Cultured lymphocytes were stimulated with phytohemagglutinin (PHA) and gamma interferon (IFN-γ) levels were measured in the culture supernatant of stimulated and non-stimulated samples using ELISA.Results: The enrolled infants were 14 to 24 months old (mean 19.2 ± 3.13 months). They were 17 boys (68 %) and 8 girls (32 %). Candida skin test was positive in 17 out of the 25 infants (68%). All infants showed increased IFN-γ levels after PHA stimulation (mean ± SD: 0.83±0.29 ng/ml) compared to basal levels (mean ± SD = 0.16 ± 0.16 ng/ml). The increase of IFN γ levels after PHA stimulation ranged from 1.54 to 38 folds. Infants with positive and negative candida tests showed comparable results in terms of clinical and immunological assessment except for weight percentiles for age that were higher among candida positive group.Conclusion: Candida intradermal test is a cost-effective simple test for evaluation of T cell function with 70 % sensitivity in healthy infants above the age of one year.Keywords: Candida, IFN-γ, infants, intradermal, lymphocyte proliferation, PHA stimulation, T cell, Tuberculi

The dilemma of widal test - which brand to use? a study of four different widal brands: a cross sectional comparative study

<p>Abstract</p> <p>Background</p> <p>Serodiagnosis of typhoid fever by Widal test based on demonstrating the presence of agglutinins (antibodies) in the serum of an infected patient, against the H (flagellar) and O (somatic) antigens of <it>Salmonella enterica </it>serotype Typhi has been associated with many debates. This is why the aim of this study was to: (i) Compare the diagnostic accuracy of four different commercial kits used to perform Widal test (Remel, BioSystems, Dialab and Biotec). (ii) Compare the sensitivity and specificity of both anti-O and anti-H antibodies. (iii) Compare the validity of single versus paired serum samples with a rising titer for the diagnosis of typhoid fever.</p> <p>Methods</p> <p>Duplicate serum samples were obtained from150 patients clinically diagnosed as typhoid fever patients. Moreover, single serum samples were obtained from 25 patients with febrile diseases other than typhoid fever. All samples were tested using the four different Widal brands and <it>Salmonella </it>Typhi IgM anti-LPS ELISA</p> <p>Results</p> <p><b>-</b>The results of Widal tests differed markedly using the four Widal brands in terms of sensitivity and specificity at three cut-off values of 1/80, 1/160 and 1/320. Remel brand gave the highest sensitivities and the lowest specificities and Dialab brand gave the highest specificities and the lowest sensitivities for both anti-O and anti-H antibodies at the three cut-off values.</p> <p><b>-</b>Four fold rise in the antibodies titer was not demonstrable among clinically diagnosed typhoid fever patients</p> <p>-H agglutinins were less sensitive and less specific than O agglutinins</p> <p>Conclusions</p> <p>-Widal test results showed marked discrepancies using different Widal brands. None of the serum samples of the typhoid fever patients showed four fold rise in the antibody titers. Raised O agglutinins were of slightly greater diagnostic value than raised H agglutinins.</p> <p>Significance and impact of study</p> <p>Widal test done sequentially using two brands could be of value in typhoid fever diagnosis. Single serum sample could be used for typhoid fever diagnosis relying on anti O titer.</p

Protective and therapeutic effects of cannabis plant extract on liver cancer induced by dimethylnitrosamine in mice

Hepatocellular carcinomas will emerge as a major form of malignancy in the coming decades. When these tumors are in advanced stages, few therapeutic options are available. Therefore, it is essential to search for new treatment modalities to fight this disease.Aim: Evaluate the possible protective and therapeutic effects of Cannabis extract on dimethylnitrosamine (DMNA)-induced hepatocarcinogenicity in mice.Methods: Seventy-five male mice were divided into five groups of 15 each: group I mice received corn oil only as the control group; group II mice were injected intraperitoneally with DMNA (10 lg/kg body weight) weekly for 12 weeks; group III mice were pretreated orally with cannabis extract (0.5 ml/kg body weight) every other day for two weeks before the injection of DMNA, and continued until the end of the experiment (12 weeks); group IV mice were treated orally with cannabis extract every other day simultaneously with DMNA injection and continued until the end of the experiment; group V mice were treated orally with cannabis extract every other day after receiving the last intraperitoneal injection of DMNA. A real time PCR was used to quantify telomerase reverse transcriptase and caspase-8 m-RNA expression level. Results: As compared to the control group, mTERT mRNA expression level was significantly increased in group II. The gene in groups (III, IV, and V) was insignificantly higher than the control group but it was significantly decreased as compared to group II. The caspase-8 mRNA expression level was significantly decreased in all groups as compared to the control group. As compared to group II, caspase-8 mRNA level was significantly increased in group III. Conclusion: The protective effect of cannabis extract is more pronounced in group taking cannabis before DMNA. Cannabinoids might exert their anti-tumor effects by the direct induction of apoptosis and can decrease telomerase activity by inhibiting the expression of the TERT gene. Coordination between inhibition of telomerase activity and induction of apoptosis might be a potential therapeutic agent for cancer treatment. KEYWORDS Hepatocellular carcinoma; Cannabis; mTERT; Caspase-