The Association Between Social Networks and Self-rated risk of HIV Infection among Secondary School Students in Moshi Municipality, Tanzania.

Abstract This study describes the social networks of secondary school students in Moshi Municipality, and their association with self-rated risk of human immunodeficiency virus (HIV) infection. A cross-sectional analytical study was conducted among 300 students aged 15-24 years in 5 secondary schools in Moshi, Tanzania. Bonding networks were defined as social groupings of students participating in activities within the school, while bridging networks were groups that included students participating in social groupings from outside of the school environs. A structured questionnaire was used to ask about participation in bonding and bridging social networks and self-rated HIV risk behavior. More participants participated in bonding networks (72%) than in bridging networks (29%). Participation in bridging networks was greater among females (25%) than males (12%, p < .005). Of 300 participants, 88 (29%) were sexually experienced, and of these 62 (70%) considered themselves to be at low risk of HIV infection. Factors associated with self-rated risk of HIV included: type of school (p < .003), family structure (p < .008), being sexually experienced (p < .004), having had sex in the past three months (p < .009), having an extra sexual partner (p < .054) and non-condom use in last sexual intercourse (p < .001), but not the presence or type of social capital. The study found no association between bonding and bridging social networks on self-rated risk of HIV among study participants. However, sexually experienced participants rated themselves at low risk of HIV infection despite practicing unsafe sex. Efforts to raise adolescents' self-awareness of risk of HIV infection through life skills education and HIV/acquired immunodeficiency syndrome risk reduction strategies may be beneficial to students in this at-risk group

SSR Polymorphism of Alligator sinesis and Conservation Strategy of Genetic Diversity

作者简介: 黄 磊( 1978- ) , 硕士研究生, 研究方向: 动物分子遗传 通讯作者。E-mail:wangyqnj@ jlonline. com[中文文摘]扬子鳄 (Alligatorsinensis)是中国特有的珍稀保护动物 ,为保护这一濒危物种 ,我国于 80年代初在安徽宣州先后建立了扬子鳄繁殖研究中心和国家级扬子鳄自然保护区 ,现饲养种群存鳄数量已达 10 0 0 0余头。为了揭示扬子鳄种群的遗传结构 ,共采集了 3 9个个体的样品 ,其中包括 6件剥制标本 ,按代系不同 ,分为野生群、F1代饲养群及F2 代饲养群 ,用微卫星DNA分子标记对其进行研究。分析结果显示 :扬子鳄种群在微卫星水平表现出很低的遗传多样性 ,平均等位基因数A =2 3 8,平均有效等位基因数Ne=1 60 ,平均观察杂合度Ho=0 3 74,平均期望杂合度He=0 3 50 ,平均多态信息含量PIC =0 3 2 7,3个群体间A、Ne、Ho、He、PIC及各微卫星位点等位基因频率分布无显著差异 ,但F2 代饲养群在Ami μ 6和Ami μ 2 2 2两个位点表现出极显著的遗传不平衡。扬子鳄种群遗传多样性水平低下的主要原因是近几十年来种群数量大幅减少造成 ,现阶段应将全部现存的扬子鳄作为一个整体加以保护 ,在建立新的繁殖群体时 ,应考虑保存物种遗传多样性所必需的有效种群大小 ,在种群的遗传管理上应注重低频等位基因的发现和保持.[英文文摘]Chinese alligator, Alligator sinesis , is a critically endangered endemic species under legislative protection. Results of recent investigations revealed that the number of the alligator was continuously declining in the past 50 years and less than 150 individuals were surviving in the wild until 2000. In order to prevent the extinguishing of this species, the Reproductive Research Center of Alligator sinesis and the National Nature Reserve of Alligator sinesis were set up in early 1980 s in Xuanzhou, Anhui Province. After 20 years of breeding efforts, the number of captive individuals has been brought up to more than 10, 000 in total. In order to reveal the genetic structure of Chinese alligator population, total of 39 individuals including 7 wild individuals outside of the research center were sampled to construct wild, F1 and F2 groups according to their generations, and 10 micorsatellite loci selected from 25 primer pairs originally designed for Alligator mississippiensis were employed for investigating the genetic diversity of Alligator sinesis .The results indicated that, contrasting with Alligator mississippiensis and some other endangered species, Chinese alligator had an extremely low genetic diversity level with A= 2.38, Ne= 1.60, Ho= 0.374, He= 0.350 and PIC= 0.327. There were no significant differences of A, Ne , Ho , He , PIC and each SSR locus alleles frequency distribution among 3 groups. However, Hardy Weinberg equilibrium analysis revealed that F2 captive group showed a remarkable genetic disequilibrium at loci Ami μ 6 and Ami μ 6 222 . The reason accounting for the current genetic status of Chinese alligator is dramatically shrink of the population in past decades. Due to the lack of significant difference between wild group and captive group, all survived Chinese alligator should be treated as one ESU in the next conservation practice. More attention regarding the effective population size and low frequency alleles should be emphasized in genetic management of captive alligators and establishing new separate propagation.教育部骨干教师资助计划项目(编号:GG18021002403 1740);教育部留学回国人员启动基金资

Slow relaxation in the two dimensional electron plasma under the strong magnetic field

We study slow relaxation processes in the point vortex model for the two-dimensional pure electron plasma under the strong magnetic field. By numerical simulations, it is shown that, from an initial state, the system undergoes the fast relaxation to a quasi-stationary state, and then goes through the slow relaxation to reach a final state. From analysis of simulation data, we find (i) the time scale of the slow relaxation increases linearly to the number of electrons if it is measured by the unit of the bulk rotation time, (ii) during the slow relaxation process, each electron undergoes an superdiffusive motion, and (iii) the superdiffusive motion can be regarded as the Levy flight, whose step size distribution is of the power law. The time scale that each electron diffuses over the system size turns out to be much shorter than that of the slow relaxation, which suggests that the correlation among the superdiffusive trajectories is important in the slow relaxation process.Comment: 11pages, 19 figures. Submitted to J. Phys. Soc. Jp

Advancing national greenhouse gas inventories for agriculture in developing countries : improving activity data, emission factors and software technology

Peer reviewedPublisher PD

Phase-Field Approach for Faceted Solidification

We extend the phase-field approach to model the solidification of faceted materials. Our approach consists of using an approximate gamma-plot with rounded cusps that can approach arbitrarily closely the true gamma-plot with sharp cusps that correspond to faceted orientations. The phase-field equations are solved in the thin-interface limit with local equilibrium at the solid-liquid interface [A. Karma and W.-J. Rappel, Phys. Rev. E53, R3017 (1996)]. The convergence of our approach is first demonstrated for equilibrium shapes. The growth of faceted needle crystals in an undercooled melt is then studied as a function of undercooling and the cusp amplitude delta for a gamma-plot of the form 1+delta(|sin(theta)|+|cos(theta)|). The phase-field results are consistent with the scaling law "Lambda inversely proportional to the square root of V" observed experimentally, where Lambda is the facet length and V is the growth rate. In addition, the variation of V and Lambda with delta is found to be reasonably well predicted by an approximate sharp-interface analytical theory that includes capillary effects and assumes circular and parabolic forms for the front and trailing rough parts of the needle crystal, respectively.Comment: 1O pages, 2 tables, 17 figure

What’s Sex (Composition) Got to Do with It? The Importance of Sex Composition of Gangs for Female and Male Members’ Offending and Victimization

Sex composition of groups has been theorized in organizational sociology and found in prior work to structure female and male members’ behaviors and experiences. Peer group and gang literature similarly finds that the sex gap in offending varies across groups of differing sex ratios. Drawing on this and other research linking gang membership, offending, and victimization, we examine whether sex composition of gangs is linked to sex differences in offending in this sample, further assess whether sex composition similarly structures females’ and males’ victimization experiences, and if so, why. Self-report data from gang members in a multi-site, longitudinal study of 3,820 youths are employed. Results support previous findings about variations in member delinquency by both sex and sex composition of the gang and also indicate parallel variations in members’ victimization. These results are further considered within the context of facilitating effects such as gender dynamics, gang characteristics, and normative orientation

Comparing public and private hospitals in China: Evidence from Guangdong

<p>Abstract</p> <p>Background</p> <p>The literature comparing private not-for-profit, for-profit, and government providers mostly relies on empirical evidence from high-income and established market economies. Studies from developing and transitional economies remain scarce, especially regarding patient case-mix and quality of care in public and private hospitals, even though countries such as China have expanded a mixed-ownership approach to service delivery. The purpose of this study is to compare the operations and performance of public and private hospitals in Guangdong Province, China, focusing on differences in patient case-mix and quality of care.</p> <p>Methods</p> <p>We analyze survey data collected from 362 government-owned and private hospitals in Guangdong Province in 2005, combining mandatorily reported administrative data with a survey instrument designed for this study. We use univariate and multi-variate regression analyses to compare hospital characteristics and to identify factors associated with simple measures of structural quality and patient outcomes.</p> <p>Results</p> <p>Compared to private hospitals, government hospitals have a higher average value of total assets, more pieces of expensive medical equipment, more employees, and more physicians (controlling for hospital beds, urban location, insurance network, and university affiliation). Government and for-profit private hospitals do not statistically differ in total staffing, although for-profits have proportionally more support staff and fewer medical professionals. Mortality rates for non-government non-profit and for-profit hospitals do not statistically differ from those of government hospitals of similar size, accreditation level, and patient mix.</p> <p>Conclusions</p> <p>In combination with other evidence on health service delivery in China, our results suggest that changes in ownership type alone are unlikely to dramatically improve or harm overall quality. System incentives need to be designed to reward desired hospital performance and protect vulnerable patients, regardless of hospital ownership type.</p

EFFECT OF SUGARCANE YELLOW LEAF VIRUS ON SUGARCANE YIELD AND JUICE QUALITY

Abstract In 1996, sugarcane plants infected with sugarcane yellow leaf virus (SCYLV), reported to cause yellow leaf syndrome (YLS), were discovered in Louisiana. Field experiments were established to assess the potential impact of the disease on the Louisiana sugarcane industry. In the first experiment, yield and juice quality of SCYLV-infected and non-infected plants of cultivar LCP82-89 were compared. Sugar yields per unit area were reduced 11 % and 14% in the first ratoon and second ratoon crops respectively. Stalk number and tonnage were reduced in SCYLV-infected plants. Cane quality components, % brix, % sucrose, % fibre and % purity, did not differ between infected and non-infected plants. However, % brix, % sucrose, and % purity were higher in juice from virus-infected green leaf tissue compared with healthy leaf tissue. In a second experiment, juice from leaves and stalks of infected and non-infected plants collected from plant cane, first ratoon, and second ratoon crops of cultivars LCP82-89 and LHo83-153 was analysed. Cane quality components did not differ in either cultivar. In juice from SCYLV-infected leaves, % sucrose was higher in LCP82-89 and % purity and starch concentrations were higher in both cultivars, while differences in total polysaccharides and oligosaccharides were not detected. Dextran content was inconsistent. The uppermost green leaves are normally removed from the stalk during mechanical harvesting; however, they may not be removed if the cane is lodged. Leaves delivered to the mill containing elevated levels of starch might reduce processing efficiency