24,836 research outputs found
Prevalence and correlates of physical assault on dating partners
This paper examines the prevalence and correlates of dating partner violence in a cohort of 1,736 university students from Hong Kong and the United States. The participants completed the Revised Conflict Tactics Scale and the Personal and Relationships Profile to report on the rates of occurrence of physical assault and injury. The differences between the two sites were compared using independent t-tests. Logistic regression was employed to predict the presence or absence of physical assault in the previous year of reporting based on the demographic variables. Results showed that more Hong Kong students reported physical assault than did US students. A combination of the perpetrator-related demographic characteristics, and relationship and personal factors accounted for the differences in the preceding-year prevalence of physical assault perpetration in the two samples. To further investigate dating violence in diverse social settings, cultural factors correlated to dating violence should be taken into consideration.published_or_final_versio
Improving honey production in worker bees (Apis mellifera adansoni L.) hymenoptera: apidae through artificial modification of their feeding activities.
Modification of feeding activity, nursing care and undertaker behaviour were carried out among some colonies of honey bees Apis mellifera adansoni L to know the effect on honey production. Apiaries Numbers 1, 2 and 3 contain three replicates of experimental hives while apiary Number 4 contains control hives. All the hives were baited with honey to attract bees. In Apiary No. 1 (Hives A1, A2 and A3) the bee colonies were fed with banana paste which contains amino acid dopamine. The foragers population count was 9324 ± 256 ( χ ± s.e.) and the honey producedweighed 16.24 ± 0.71 kg (χ ± s.e.).In Apiary No.2 (Hives B1, B2 and B3), some young nursing care worker bees were removed from the bee colonies, thus making the old foraging worker bees to perform nursing care duty. The foragers population count was 6714 ± 256 ( χ ± s.e.) while honey produced weighed 6.03 ± 0.71 kg ( χ ± s.e). Dead bodies of insects and dirt were introduced into the hives in Apiary No.3 (HivesC1, C2 and C3) to induce undertaker behaviour in the colony. Some of the old foraging worker bees assumed undertaker duty in these hives where the population count of the foraging workers was 5466 ±256 (χ ± s.e.) and the honey yield weighed 7.02 ± 0.71 kg ( χ ± s.e.). In the control Apiary (Hives D1, D2 and D3), where the bee colonies were baited with honey only, foraging worker bees population count was 8670 ± 256 (χ ± s.e.) and honey produced weighed 13.13 ± 0.71 kg ( χ ± s.e.). The differences between the mean foraging worker bees’ population and consequently honey yield in the different treatments were statistically significant with the apiary where banana paste was introduced containing the highest. When pollen and nectar is abundant, the number of foraging worker bees determines the honey yield. Feeding of the beecolonies with banana paste slightly increased the population growth of the foraging worker bees and the honey yield
Mechanisms of dysregulation of low-density lipoprotein receptor expression in vascular smooth muscle cells by inflammatory cytokines
Objective - Although inflammation is a recognized feature of atherosclerosis, the impact of inflammation on cellular cholesterol homeostasis is unclear. This study focuses on the molecular mechanisms by which inflammatory cytokines disrupt low-density lipoprotein (LDL) receptor regulation.Methods and Results - IL-1 beta enhanced transformation of vascular smooth muscle cells into foam cells by increasing uptake of unmodified LDL via LDL receptors and by enhancing cholesterol esterification as demonstrated by Oil Red O staining and direct assay of intracellular cholesterol concentrations. In the absence of IL-1 beta, a high concentration of LDL decreased LDL receptor promoter activity, mRNA synthesis and protein expression. However, IL-1 beta enhanced LDL receptor expression, overriding the suppression usually induced by a high concentration of LDL and inappropriately increasing LDL uptake. Exposure to IL-1 beta also caused overexpression of the sterol regulatory element binding protein ( SREBP) cleavage-activating protein ( SCAP), and enhanced its translocation from the endoplasmic reticulum to the Golgi, where it is known to cleave SREBP, thereby enhancing LDL receptor gene expression.Conclusions - These observations demonstrate that IL-1 beta disrupts cholesterol-mediated LDL receptor feedback regulation, permitting intracellular accumulation of unmodified LDL and causing foam cell formation. The implication of these findings is that inflammatory cytokines may contribute to intracellular LDL accumulation without previous modification of the lipoprotein
Effects of seawater alkalinity on calcium and acid-base regulation in juvenile European lobster (Homarus gammarus) during a moult cycle
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Fluxes of NH4(+) (acid) and HCO3(-) (base), and whole body calcium content were measured in European lobster (Homarus gammarus) during intermoult (megalopae stage), and during the first 24h for postmoult juveniles under control (~2000μeq/L) and low seawater alkalinity (~830μeq/L). Immediately after moulting, animals lost 45% of the total body calcium via the shed exoskeleton (exuvia), and only 11% was retained in the uncalcified body. At 24h postmoult, exoskeleton calcium increased to ~46% of the intermoult stage. Ammonia excretion was not affected by seawater alkalinity. After moulting, bicarbonate excretion was immediately reversed from excretion to uptake (~4-6 fold higher rates than intermoult) over the whole 24h postmoult period, peaking at 3-6h. These data suggest that exoskeleton calcification is not completed by 24h postmoult. Low seawater alkalinity reduced postmoult bicarbonate uptake by 29% on average. Net acid-base flux (equivalent to net base uptake) followed the same pattern as HCO3(-) fluxes, and was 22% lower in low alkalinity seawater over the whole 24h postmoult period. The common occurrence of low alkalinity in intensive aquaculture systems may slow postmoult calcification in juvenile H. gammarus, increasing the risk of mortalities through cannibalism.The authors would like to acknowledge and thank Dom Boothroyd and Carly Daniels at the National Lobster Hatchery (Padstow, North Cornwall, U.K.) for provision of animals used in this research, and for the valuable comments made by the anonymous reviewers of this manuscript. The analytical equipment used in these experiments were funded through BBSRC and NERC grants to RWW (BB/F009364/1, NE/H010041/1 and BB/J00913X/1)
Ecofriendly and Nonvacuum Electrostatic Spray-Assisted Vapor Deposition of Cu(In,Ga)(S,Se)2 Thin Film Solar Cells
Chalcopyrite Cu(In,Ga)(S,Se)2 (CIGSSe) thin films have been deposited by a novel, nonvacuum, and cost-effective electrostatic spray-assisted vapor deposition (ESAVD) method. The generation of a fine aerosol of precursor solution, and their controlled deposition onto a molybdenum substrate, results in adherent, dense, and uniform Cu(In,Ga)S2 (CIGS) films. This is an essential tool to keep the interfacial area of thin film solar cells to a minimum value for efficient charge separation as it helps to achieve the desired surface smoothness uniformity for subsequent cadmium sulfide and window layer deposition. This nonvacuum aerosol based approach for making the CIGSSe film uses environmentally benign precursor solution, and it is cheaper for producing solar cells than that of the vacuum-based thin film solar technology. An optimized CIGSSe thin film solar cell with a device configuration of molybdenum-coated soda-lime glass substrate/CIGSSe/CdS/i-ZnO/AZO shows the photovoltaic (j-V) characteristics of Voc = 0.518 V, jsc = 28.79 mA cm(-2), fill factor = 64.02%, and a promising power conversion efficiency of η = 9.55% under simulated AM 1.5 100 mW cm(-2) illuminations, without the use of an antireflection layer. This demonstrates the potential of ESAVD deposition as a promising alternative approach for making thin film CIGSSe solar cells at a lower cost
Effect of Sodium Treatment on the Performance of Electrostatic Spray Assisted Vapour Deposited Copper-poor Cu(In,Ga)(S,Se)2 Solar Cells
In our work, eco-friendly, non-vacuum and low cost Electrostatic Spray Assisted Vapour Deposition (ESAVD) method has been used to produce Cu(In,Ga)(S,Se) 2 (CIGS) solar cells. Copper (Cu) deficient (Cu/In + Ga = 0.76) CIGS films were designed to avoid the rather dangerous KCN treatment step for the removal of conductive minor phases of Cu 2 S/Cu 2 Se. A simple sodium (Na) treatment method was used to modify the morphology and electronic properties of the absorber and it clearly improved the solar cell performance. The SEM and XRD results testified a slightly increase of the grain size and (112) crystal orientation in the Na-incorporated CIGS thin films. From the Mott-schottky results, it can be seen that the functions of the Na treatment in our non-vacuum deposited CIGS are mainly used for defect passivation and reduction of charge recombination. Photovoltaic characteristics and j-V curve demonstrated that the dipping of CIGS films in 0.2 M NaCl solution for 20 minutes followed by selenization at 550 °C under selenium vapor resulted in the optimum photovoltaic performance, with j sc , V oc , FF and η of the optimized solar cell of 29.30 mA cm -2 , 0.564 V, 65.59% and 10.83%, respectively
Moving crack with a contact zone at interface of magnetoelectroelastic bimaterial
The plane-strain problem of a moving crack at the interface of two dissimilar magnetoelectroelastic (MEE) materials is investigated. Assuming that the crack moves at a constant speed in the subsonic regime, a fracture analysis of a finite crack under concentrated loading imposed onto the crack face is first carried out. By applying magnetoelectric (ME) permeable boundary conditions at the crack face, a combined Dirichlet-Riemann problem is formulated and solved analytically. The expressions for the fracture parameters, including the relative length of the contact zone and field intensity factors (FIFs), are obtained in the analytical form. A crack of a semi-infinite length with a contact zone under concentrated loading is further presented as a specific case examined with the obtained solution. Then a moving crack of finite length at the interface under remote mix-mode loading is also analyzed and the corresponding fracture parameters are presented in an analytical form. Finally, numerical examples are provided for the material combination of barium titanate-cobalt ferrite composites to examine the influence of the speed of the moving crack, poling direction, material volume fraction, load position and load ratio on the fracture parameters, from which some new and interesting conclusions related to the crack model in this study are drawn
Challenges associated with the honey bee (Apis Mellifera Adansonii) colonies establishment in South Western Nigeria
The southwestern part of Nigeria is a tropical rainforest region having many local beekeepers. These beekeepers have experienced decline in colony establishment in the recent past. A study carried out in Lagos, Ogun and Osun states between December 2009 and September 2011 examined 14 randomly selected commercial bee farms for problems associated with decline in colony establishment. Sampling and treatments were split equally between each apiary and three colonies were selected in each. All the colonies were housed in Tanzania/local top bar hives. There were 58.34, 44.84 and 40.61 average percentage declines in colony establishment in Lagos, Ogun and Osun States, respectively. Presence of pests and diseases, pesticide poisoning, poor hive and seasonal management, ecological problem and lack of queen rearing were potential problems identified by the beekeepers. All the apiaries had pests like Crickets, Ants (Companotus pennsylvanicus), Small Hive beetle (Aethina tumida), Termites (Macrotermes spp) and Spider (Lactrodectus mactan). Varroa mite infestations were found in 33 (78.57%) of apiaries sampled. There was no significant difference between the levels of Varroa infestation in all the colonies during the dry and wet seasons at confidence interval of 95 percent (t = 1.542, df = 13, p = 0.147 (p> 0.05). Nosema spores were found in 27 (64.29%) colonies examined. The number of spores range from 16 x 103 to 30.4 x 103. There were no significant differences in the infection from colony to colony, apiary to apiary and between dry and wet seasons (t = - 0.094 df = 11, P = 0.927 (P > 0.05). Diseases like American and European foulbrood were absent while chalkbrood disease was prevalent. Environmental factors of high temperature, high rainfall and high relative and hive humidity enhanced the spread of pests and disease pathogens. Many insecticides were constantly applied by the farmers on the crops in the surrounding farmland. Two of the commonly used insecticides DDVP (Dichlorvos) and Cyperforce (Cypermetrin) were discovered to have increased mortality on worker honey bees with progressively larger doses. It was obvious that insecticide toxicity had a significant effect on the colony. Hence, ecological and management problems had contributed to the decline in colony establishment in this area.Keywords: colony, decline, varroasis, infestation, toxicityAfrican Journal of Food, Agriculture, Nutrition and Development, Volume 13 No. 2 April 201
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