Performance Investigation of Wireless LAN with Variable Channel Width

Today, mostly the wireless LAN is based on preset static channel widths. Considering unique benefits of adapting channel width, which is a fundamental yet under-explored facet in wireless communication, We carried out investigations on the performance of suggested scenario, which are based on IEEE 802.11 and composed of different number of nodes with different channel width (10MHz, 20 MHz and 40 MHz) associated to one AP. This research work makes a strong case for wireless systems that adapt channel width in WLAN. Adapting channel width offers rich possibilities for improving system performance. This thesis provides an outlook of the aforementioned issues associated with wireless communication for instance, fairness problem among users associated to same AP and hidden terminal problem. Some issues are investigated and analyzed with Matlab tool. We found that the variable channel width increases the range of communication, providing the users with the required spectrum, which offers a natural way to both improve flow fairness and balance the load across the APs. Also the increase in channel width increases the throughput of suggested scenario compare to the fixed channel width. In our future work, we also provide possible solutions to the new problems in WLAN with variable channel width

Efficient Handoff for QoS Enhancement in Heterogeneous Wireless Networks (UMTS/WLAN Interworking)

Today’s Wireless Communications technologies prove us that wireless communications will in the long run be composed of different communication networks as a way to benefit from each other. This can however be achieved from cellular networks and wireless local area networks that show some compatible characteristics that enable them be integrated. Scenarios typically behind these integrations is the UMTS and WLAN interworking where UMTS network is known for its wide area of coverage and nearly roaming however, known for lack of enough data rate. This is contrary with WLAN which is known for high data rate and cheaper compared to UMTS. WLAN however has a small area of coverage and lacks roaming. This in regard brings the idea that the two different networks being integrated could provide the means for mobile users to be gratified with a supported coverage and quality at anywhere and anytime with seamless access to internet

Predictors of the usuage of contraceptive implants among women of reproductive age in Ondo State, Southwest Nigeria.

ABSTRACT Background A major characteristic of all developing countries is rapid population growth which is due to high fertility, birth rates and poor utilization of contraceptive methods. This study therefore assessed the predictors of contraceptive implants utilization among women of reproductive age in Ondo State, Nigeria. Methods A descriptive cross sectional study design was used and a total of 230 women were selected by multi-stage sampling technique. Questionnaire administration was interviewer-based majority of the women could not read. Data analysis was conducted using SPSS version 23. Research questions and hypotheses were answered and tested with descriptive statistics (frequency, percentages), chi-square test of significance and binary logistic regression. Levels of significance was set at p ≤ 0.05. Results The prevalence of contraceptive utilization (any method) and contraceptive implant utilization were 92.2% and 31.1% respectively. Variables such as education (χ2 = 6.91, p = 0.03) and lack of counseling from providers (χ2 = 5.05, p = 0.03) were significantly associated with the utilization of contraceptive implant. These two variables were also the predictors of contraceptive implant utilization. Women with secondary and tertiary education have higher odds of utilizing contraceptive implants (OR = 1.21, 95% CI = 1.01 – 7.82, p = 0.04) and (OR = 2.53, 95% CI = 1.49 – 11.47, p = 0.03) compared to women who had primary or no education while those who claimed to be adequately counseled by providers are about two times more likely to use contraceptive implants (OR = 2.33, 95% CI = 1.08 – 5.51) Conclusion This study showed the important role of education and health workers in providing information about contraceptive implants. Therefore, health workers’ knowledge of family planning counseling and services should be constantly upgraded so as to improve their roles in educating, mobilizing, counseling the women regarding contraceptive implant insertion.                           &nbsp

Modelling and optimization of the drying process and the quality parameters of dried osmo-pretreated onions (Allium cepa)

Modelling and optimization represent an important aspect of drying in food processing, providing a fast and convenient means for quality prediction. The research focuses on modelling and optimization of process parameters such as drying rate, water loss, solid gain, vitamin C, manganese, and iron of dried osmo-pretreated onion slices. Least square regression analysis in the Math-lab computer software was used to model and optimise the process parameters., Six (6) mathematical models were developed for each output from the regression analysis that was carried out. The criteria for adjudging these models were the values of their adjusted coefficient of multiple determinations, prediction error sum of squares (also called deleted residual), R2 for prediction, coefficient of variation CV, and the Dubin-Watson test for autocorrelation. The models were checked for adequacy using these criteria, and those found to be adequate were selected from among the other possible combinations. Hence, the best-optimized obtained results from the models are 27.50 g/h, 1.61 g/g, 0.15 g/g, 77.52 mg/100 g, 2.79 mg/1000 g, and 2.19 mg/1000 g for drying rate, water loss, solid gain, vitamin C, manganese, and iron, respectively

Prevalence and Predictors of Risk Factors for Brucellosis Transmission by Meat Handlers and Traditional Healers’ Risk Practices in Ibadan, Nigeria

Introduction: Brucellosis is endemic in Nigeria and risk factors enhancing its transmission are prevalent.Methods: Following serological evidence of brucellosis and isolation of B. abortus from slaughtered cattle in Ibadan, Nigeria, we administered a semi-structured questionnaire to determine the prevalence and predictors of eating and selling bovine gravid uterus among 350 meat handlers from five major meat processing facilities and conducted key informant interview for five leading traditional healers to document its use. Data were analysed using Stata 12.Results: The prevalence of eating and selling gravid uterus were respectively, 29.7% and 40.3%. Being meat/offal processor (OR=1.9, 95%CI: 1.11-3.3, P =0.008), male (OR=1.7, 95%CI: 0.1-3.03, P =0.023) and not knowing that eating undercooked contaminated gravid uterus could expose humans to brucellosis (OR=2.4, 95%CI: 1.56-3.62, P =0.000) were strong predictors of eating gravid uterus. Similarly, being adult (OR=1.7, 95%CI: 1.08-2.57, P =0.02) and inadequate knowledge of brucellosis as a zoonosis (OR=2.9, 95%CI: 1.71-4.92, P =0.000) strongly predicted selling gravid uterus. Qualitative data from the traditional healers revealed using gravid uterus as special medicinal preparations to hasten parturition in overdue pregnancies, treat infertility and old age diseases in humans.Discussions: We demonstrated high prevalence of risk factors for brucellosis transmission and some meat handlers’ socio-demographic characteristics including brucellosis knowledge-based markers as predictors of these factors. The traditional healers’ practices portend a challenge to the current brucellosis control strategy. These findings provide insights into designing all-inclusive health programmes aimed at controlling brucellosis spread in Nigeria and other similar settings in developing countries

Comparative Analysis of Selected Animal and Vegetable Oils Suitability in Machining of Plain Carbon Steels

Due to the alarming rate in public awareness on environmental issues, there has been growing demand for biodegradable materials which has opened an avenue for using vegetable and animal oils as alternatives to petroleum-based polymeric materials in the market, most especially in machining operations. Thus, research on biodegradable functional fluids has emerged as one of the top priorities in lubrication, due to their applicability in many diverse areas. In this quest, there is need to conduct machining trials to determine the suitability of these oils in metal cutting (turning) operations of plain carbon steels. This study investigate the effect of the selected cutting fluids on certain parameters like machine removal rate (MRR), machining time, tool wear and spindle power consumption, etc. under different machining combination in turning operations of plain carbon steels obtained from universal steel Ikeja, Nigeria, using 150 x 10 HSS cutting tool. The selected oils purchased from Ogunpa market in Ibadan, Nigeria, were sieved to remove any foreign particles or dirt. The solution; water, based-oil, and emulsifier (to allow thorough mixing of water and oil without separation), were mix at an elevated temperature of 550C in a proportion 4:1:3. Experimental results clearly showed that Conventional cutting fluid might be replaced with Non-conventional cutting fluids (vegetable and animal based) as they give better performance. With slight modifications and deliberate but careful alterations in some of the components of such oils, even better performing cutting fluids could be obtained

Performance Characteristics of a Single-Cylinder Two-Stroke Diesel Engine using Diesel-RK Software

The demand for software that is capable of solving internal combustion engines (ICEs) simulation problems is increasing on a daily basis. Thus, this article presents the application of Diesel-RK in investigating the performance characteristics of a single cylinder two- stroke turbocharged Hesselman’s diesel engine with direct fuel injection. Three different engine operating speed 1500, 2000 and 2500 rpm, respectively were utilized and their effects on certain engine performance parameters were investigated numerically. The highest overall specific fuel consumption and engine efficiency of 0.53342 kg/kWh and 0.1588, respectively were obtained at 2000 rpm. More power was delivered at 2000 rpm as a result of the highest value of engine torque obtained at that speed. The cylinder pressure increases significantly as the engine speed increases at ivc (2.0451 bar), evo (3.7801 bar) and tdc (60.141 bar), respectively. This indicates that the pressure developed when the inlet valve closes increases as the piston translate from bdc to tdc on compression, to the value required for combustion and this value dropped as the exhaust valve opens. However, the optimal values corresponding cylinder temperature increases significantly at ivc (717.24 K), evo (1088.5 K) and tdc (1560.8 K), respectively at a speed of 2500 rpm. Also, the engine speed had appreciable impact on the heat exchange parameters, because the values of those parameters increases as the engine speed increases. The effect of engine speed on the ecological, combustion, turbocharged and gas exchange parameters were also studied using Bosch, Hartridge and Strouhal dimensionless numbers and it is evident that engine speed is significant in the study of engine performance parameters and the best values of those parameters were obtained at 2000 rpm

The importance of autosomal genes in Kallmann syndrome: genotype-phenotype correlations and neuroendocrine characteristics

7 pages, 2 figures, 2 tables.-- et al.Kallmann syndrome (KS) consists of congenital, isolated, idiopathic hypogonadotropic hypogonadism (IHH) and anosmia. The gene responsible for the X-linked form of KS, KAL, encodes a protein, anosmin, that plays a key role in the migration of GnRH neurons and olfactory nerves to the hypothalamus. In addition to X-linked pedigrees, autosomal dominant and recessive kindreds with KS have been reported. The relative importance of these autosomal vs. X-linked genes in producing KS, and the frequency of KAL mutations, are currently unknown because these are rare disorders and large series are unusual. We examined 101 individuals with IHH (+/- anosmia) and their families to determine their modes of inheritance, incidence of mutations in the coding sequence of KAL, genotype-phenotype correlations, and [in a subset (n = 38)] their neuroendocrine phenotype. Of the 101 patients, 59 had true KS (IHH + anosmia/hyposmia); whereas, in the remaining 42, no anosmia was evident in the patients or their families. Of the 59 KS patients, 21 were familial, whereas 38 were sporadic cases. Mutations in the coding sequence of KAL were identified in only 3 of 21 familial cases (14%) and 4 of 38 (11%) of the sporadic cases. Of the X-linked cases confirmed by mutational analysis, only 1 of 3 pedigrees appeared X-linked by inspection whereas the other 2 contained only affected brothers. Female members of known KAL mutation families (n = 3) exhibited no reproductive phenotype and were not anosmic, whereas families with anosmic women (n = 3) were not found to carry mutations in KAL. Mutations were uniformly absent in nonanosmic IHH probands (n = 42), as well as in families with both anosmic and nonanosmic members (n = 2). Overall, 4 novel mutations were identified (C172R, R191x, R457x, and delC@L600). With respect to neuroendocrine phenotype, KS men with documented KAL mutations (n = 8) had completely apulsatile LH secretion, whereas those with autosomal modes of inheritance demonstrated a more variable spectrum with evidence of enfeebled (but present) GnRH-induced LH pulses. Our conclusions are: 1) Confirmed mutations in the coding sequence of the KAL gene occur in the minority of KS cases, i.e. only 14% of familial and 11% of sporadic cases; 2) The majority of familial (and presumably sporadic) cases of KS are caused by defects in at least two autosomal genes that are currently unknown; 3) Obligate female carriers in families with KAL mutations have no discernible phenotype; 4) KAL mutations are uniformly absent in patients with either normosmic IHH or in families with both anosmic and nonanosmic individuals; and 5) Patients with KAL mutations have apulsatile LH secretion consistent with a complete absence of GnRH migration of GnRH cells into the hypothalamus, whereas evidence of present (but enfeebled) GnRH-induced LH pulses may be present in autosomal KS cases. Taken together, these findings suggest that autosomal genes account for the majority of familial cases of KS, and that unique neuroendocrine phenotypes consistent with some GnRH neuronal migration may exist in these patients.Supported by funding from CAPES, Brasilia, Brazil (to L.M.B.O.).Peer reviewe

Associations between Cognition, Gender and Monocyte Activation among HIV Infected Individuals in Nigeria.

The potential role of gender in the occurrence of HIV-related neurocognitive impairment (NCI) and associations with markers of HIV-related immune activity has not been previously examined. In this study 149 antiretroviral-naïve seropositive subjects in Nigeria (SP, 92 women and 57 men) and 58 seronegative (SN, 38 women and 20 men) were administered neuropsychological testing that assessed 7 ability domains. From the neuropsychological test scores was calculated a global deficit score (GDS), a measure of overall NCI. Percentages of circulating monocytes and plasma HIV RNA, soluble CD163 and soluble CD14 levels were also assessed. HIV SP women were found to be younger, more educated and had higher CD4+ T cell counts and borderline higher viral load measures than SP men. On the neuropsychological testing, SP women were more impaired in speed of information processing and verbal fluency and had a higher mean GDS than SN women. Compared to SP men, SP women were also more impaired in speed of information processing and verbal fluency as well as on tests of learning and memory. Numbers of circulating monocytes and plasma sCD14 and sCD163 levels were significantly higher for all SP versus all SN individuals and were also higher for SP women and for SP men versus their SN counterparts. Among SP women, soluble CD14 levels were slightly higher than for SP men, and SP women had higher viral load measurements and were more likely to have detectable virus than SP men. Higher sCD14 levels among SP women correlated with more severe global impairment, and higher viral load measurements correlated with higher monocyte numbers and sCD14 and sCD14 levels, associations that were not observed for SP men. These studies suggest that the risk of developing NCI differ for HIV infected women and men in Nigeria and, for women, may be linked to effects from higher plasma levels of HIV driving activation of circulating monocytes