Research on vibration characteristics of a multi-barrel artillery

The vibration of the barrel, induced by the interaction with a high-speed moving projectile, has a considerable influence on the shooting accuracy of a weapon. The finite element model of a multi-barrel was established with the goal to investigate its vibration characteristics in this paper, and the natural frequency and mode shape were analyzed by finite element method. To verify the result of finite element modal analysis (FEMA), a modal testing system basis on SC310W multi-path data-collecting system and hammer hitting method was set up. Results show that the low order vibrations of the multi-barrel artillery were mainly vertical, horizontal and torsional vibration, but the local vibration at high orders. The error of natural frequencies between the results obtained by simulation and test was 8.82 % in the first mode frequency and 1.37 % in the eighth. The FEMA can effectively simulate the actual vibration of the multi-barrel artillery

The START Study to evaluate the effectiveness of a combination intervention package to enhance antiretroviral therapy uptake and retention during TB treatment...

Background: Initiating antiretroviral therapy (ART) early during tuberculosis (TB) treatment increases survival; however, implementation is suboptimal. Implementation science studies are needed to identify interventions to address this evidence-to-program gap. Objective: The Start TB Patients on ART and Retain on Treatment (START) Study is a mixed-methods, cluster-randomized trial aimed at evaluating the effectiveness, cost-effectiveness, and acceptability of a combination intervention package (CIP) to improve early ART initiation, retention, and TB treatment success among TB/HIV patients in Berea District, Lesotho. Design: Twelve health facilities were randomized to receive the CIP or standard of care after stratification by facility type (hospital or health center). The CIP includes nurse training and mentorship, using a clinical algorithm; transport reimbursement and health education by village health workers (VHW) for patients and treatment supporters; and adherence support using text messaging and VHW. Routine data were abstracted for all newly registered TB/HIV patients; anticipated sample size was 1,200 individuals. A measurement cohort of TB/HIV patients initiating ART was recruited; the target enrollment was 384 individuals, each to be followed for the duration of TB treatment (6–9 months). Inclusion criteria were HIV-infected; on TB treatment; initiated ART within 2 months of TB treatment initiation; age ≥18; English- or Sesotho-speaking; and capable of informed consent. The exclusion criterion was multidrug-resistant TB. Three groups of key informants were recruited from intervention clinics: early ART initiators; non/late ART initiators; and health care workers. Primary outcomes include ART initiation, retention, and TB treatment success. Secondary outcomes include time to ART initiation, adherence, change in CD4+ count, sputum smear conversion, cost-effectiveness, and acceptability. Follow-up and data abstraction are complete. Discussion: The START Study evaluates a CIP targeting barriers to early ART implementation among TB/HIV patients. If the CIP is found effective and acceptable, this study has the potential to inform care for TB/HIV patients in high-burden, resource-limited countries in sub-Saharan Africa. Keywords: TB/HIV integration; implementation science; cost-effectiveness; acceptability; TB treatment succes

Efficacy and Safety of Transglutaminase-Induced Corneal Stiffening in Rabbits

Purpose: To evaluate the biomechanical efficacy and safety of in vivo microbial transglutaminase (Tgases)-induced corneal crosslinking in a rabbit model. Methods: A total of 34 white New Zealand rabbits were divided into two groups, a biochemistry group and a photochemistry group. The right eye of every rabbit was treated and left eyes served as negative controls. In the biochemistry group, a 1 U/mL solution of crosslinking agent microbial Tgases (Tgases CXL) was applied to the corneal surface, while in the photochemistry group, clinical ultraviolet A-riboflavin crosslinking (UVA/RF CXL) was used. Efficacy and safety evaluated on the 14th day after the procedures. Twelve pairs of corneal strips were harvested from the eyes of 12 euthanized rabbits in every group, and uniaxial tensile tests were performed to evaluate ex vivo biomechanical effects. The CXL-treated eye to its corresponding untreated eye ratio of tangent modulus were calculated. Another five pairs of corneal button were excised from euthanized animals in every group for corneal stroma and endothelium staining to evaluate changes in keratocyte distribution and endothelial cell damage. Results: In tensile tests, tangent modulus was statistically higher in the Tgases CXL groups under 1.0 MPa (26.59 +/- 4.54 vs. 21.47 +/- 4.72 MPa, P = 0.04) and 1.5 MPa (29.75 +/- 5.01 vs. 20.47 +/- 6.63 MPa, P = 0.00). The tangent modulus ratio of Tgases group (1.72 +/- 1.0 vs. 1.05 +/- 0.22, P = 0.04) was significantly higher than that of UVA/RF under 1.5-MPa stress. The distribution of keratocytes in the corneal stroma and the morphologies of endothelial cells were similar in Tgases CXL-treated and untreated corneas. However, in the UVA/RF CXL group, keratocytes in the anterior half of stromal thickness were lost, and clear endothelial cell apoptosis was observed. Conclusions: Tgases-CXL effectively stiffened the cornea and caused no damage to the endotheliumand keratocytes in the cornea. This crosslinking method could be useful as a next-generation treatment for corneal ectasia and could replace CXL of photochemistry

Ecstasy use and its association with sexual behaviors among drug users in new york city

ABSTRACT: In the past two decades, recreational use of ecstasy has become a growing concern in the United States, although most studies assessing ecstasy use have focused on white, middle-class adolescents who use ecstasy during raves and in clubs. We assessed the prevalence of recent ecstasy use among predominantly minority heroin, cocaine, and crack users in New York City and the association between ecstasy and sexual risk above and beyond that of the other drugs. Between 2002 and 2004, injection and non-injection heroin, crack and cocaine users (N = 534) completed a risk behavior questionnaire that included items on ecstasy use. Logistic regression was used to investigate the relation between current ecstasy use and sexual behaviors. Of 534 illicit drug users, 69.7% were aged 25 years or older, 65.2% were Hispanic, 27.9% Black and 77.4% male; 36.7% were injectors. 17.2% of respondents reported recent (last six months) ecstasy use. In a multivariable logistic regression model, current ecstasy use was associated both with initiating sex before age 14 (adjusted odds ratio (AOR) = 1.51) and having two or more partners in the past two months (AOR = 1.86) after adjusting for age at study entry, current cocaine and marijuana use and being an injection drug user. This study suggests that ecstasy use may be more prevalent among urban drug users. Ecstasy use in urban settings, beyond clubs and raves, should continue to be monitored.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/40285/2/Novoa_Ecstasy Use and Its Association With Sexual_2005.pd

Period and Birth-Cohort Effects on Age of First Phencyclidine (PCP) Use Among Drug Users in New York City, 1960 to 2000

PURPOSE: The aim of the study is to determine period and birth-cohort effects in the early initiation of phencyclidine (PCP) use in drug users in New York City (NYC). METHODS: We analyzed data collected from two surveys of street-recruited drug users in NYC. We used survival analysis and proportional hazards modeling to assess period and birth-cohort effects on risk for early initiation of PCP use. RESULTS: Of 787 participants, 292 (37.1%) had used PCP by the age of 23 years. Before 1987, there was a greater risk for initiation of PCP use through the age of 23 years (hazard ratio [HR] Z 34.77; 95% confidence interval [CI], 21.45–56.36). Proportional hazards modeling showed that those born in the 1971 to 1975 birth cohort compared with those born in 1976 to 1980 had a lower risk for initiation of PCP use through age 23 years (HR Z 0.58; 95% CI, 0.37–0.91). Other significant predictors of PCP use by age 23 included white race and having been in a juvenile detention center. CONCLUSIONS: There are period and birth-cohort differences in the likelihood of early initiation of PCP use. Changes in drug culture and social norms may influence the likelihood of initiation of PCP use. This may have implications for interventions aimed at slowing the nationwide increase in use of PCP.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/40257/2/Bryant_Period and Birth-Cohort Effects on Age_2006.pd

Risk factors for loss to follow-up prior to ART initiation among patients enrolling in HIV care with CD4+ cell count ≥200 cells/μL in the multi-country MTCT-Plus Initiative

Background: In resource-limited settings, many HIV-infected patients are lost to follow-up (LTF) before starting ART; risk factors among those not eligible for ART at enrollment into care are not well described. Methods: We examined data from 4,278 adults (3,613 women, 665 men) enrolled in HIV care through March 2007 in the MTCT-Plus Initiative with a CD4 count ≥200 cells/mm3 and WHO stage ≤ 2 at enrollment. Patients were considered LTF if > 12 months elapsed since their last clinic visit. Gender-specific Cox regression models were used to assess LTF risk factors. Results: The proportion LTF was 8.2 % at 12 months following enrollment, and was higher among women (8.4 %) than men (7.1 %). Among women, a higher risk of LTF was associated with younger age (adjusted hazard ratio [AHR]15–19/30+: 2.8, 95 % CI:2.1-3.6; AHR20–24/30+:1.9, 95 % CI:1.7-2.2), higher baseline CD4 count (AHR350–499/200–349:1.5; 95 % CI:1.0-2.1; AHR500+/200–349:1.5; 95 % CI:1.0-2.0), and being pregnant at the last clinic visit (AHR:1.9, 95 % CI:1.4-2.5). Factors associated with a lower risk of LTF included, employment outside the home (AHR:0.73, 95 % CI:0.59-0.90), co-enrollment of a family/household member (AHR:0.40, 95 % CI:0.26-0.61), and living in a household with ≥4 people (AHR:0.74, 95 % CI:0.64-0.85). Among men, younger age (AHR15–19/30+: 2.1, 95 % CI:1.2-3.5 and AHR30–34/35+:1.5, 95 % CI:1.0-2.4) had a higher risk of LTF. Electricity in the home (AHR:0.61, 95 % CI:0.41-0.91) and living in a household with ≥4 people (AHR:0.58, 95 % CI:0.39-0.85) had a lower risk of LTF. Conclusions: Socio-economic status and social support may be important determinants of retention in patients not yet eligible for ART. Among women of child-bearing age, strategies around sustaining HIV care during and after pregnancy require attention. Keywords HIV AIDS Anti-retroviral therapy Pre-ART, Lost to follow up Risk factors Social suppor

Hepatitis C Incidence- a Comparison Between Injection and Noninjection Drug Users in New York City

Hepatitis C virus (HCV) burdens injection drug users (IDUs) with prevalence estimated from 60–100% compared to around 5% among noninjection drug users (non-IDUs). We present preliminary data comparing the risk for HCV among IDUs and non-IDUs to inform new avenues of HCV prevention and intervention planning. Two cohorts, new IDUs (injecting≤ 3 years) and non-IDUs (smoke/sniff heroine, crack or cocaine≤ 10 years), ages 15–40, were street-recruited in New York City. Participants underwent risk surveys and HCV serology at baseline and 6-month follow-up visits. Person-time analysis was used to estimate annual HCV incidence. Of 683 non-IDUs, 653 were HCV seronegative, 422 returned for at least 1 follow-up visit, and 1 became HCV seropositive. Non-IDUs contributed 246.3 person-years (PY) yielding an annual incident rate of 0.4/100 PY (95% Confidence Interval [CI]=0.0-1.2). Of 260 IDUs, 114 were HCV seronegative, 62 returned for at least 1 follow-up visit, and 13 became HCV seropositive. IDUs contributed 36.3 PY yielding an annual incidence rate of 35.9/100 PY (95%CI=19.1–61.2). Among IDUs, HCV seroconverters tended to be younger (median age 25 vs. 28, respectively), and inject more frequently (61.5% vs. 34.7%, respectively) than nonseroconverters. These interim data suggest that IDUs may have engaged in high-risk practices prior to being identified for prevention services. Preventing or at least delaying transition into injection could increase opportunity to intervene. Identifying risk factors for transition into injection could inform early prevention to reduce onset of injection and risk of HCV.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/40369/2/Fuller_Hepatitis C Incidence - a Comparison Betwwen Injection_2004.pd

The genome evolution and domestication of tropical fruit mango

Background: Mango is one of the world’s most important tropical fruits. It belongs to the family Anacardiaceae, which includes several other economically important species, notably cashew, sumac and pistachio from other genera. Many species in this family produce family-specific urushiols and related phenols, which can induce contact dermatitis. Results: We generate a chromosome-scale genome assembly of mango, providing a reference genome for the Anacardiaceae family. Our results indicate the occurrence of a recent whole-genome duplication (WGD) event in mango. Duplicated genes preferentially retained include photosynthetic, photorespiration, and lipid metabolic genes that may have provided adaptive advantages to sharp historical decreases in atmospheric carbon dioxide and global temperatures. A notable example of an extended gene family is the chalcone synthase (CHS) family of genes, and particular genes in this family show universally higher expression in peels than in flesh, likely for the biosynthesis of urushiols and related phenols. Genome resequencing reveals two distinct groups of mango varieties, with commercial varieties clustered with India germplasms and demonstrating allelic admixture, and indigenous varieties from Southeast Asia in the second group. Landraces indigenous in China formed distinct clades, and some showed admixture in genomes. Conclusions: Analysis of chromosome-scale mango genome sequences reveals photosynthesis and lipid metabolism are preferentially retained after a recent WGD event, and expansion of CHS genes is likely associated with urushiol biosynthesis in mango. Genome resequencing clarifies two groups of mango varieties, discovers allelic admixture in commercial varieties, and shows distinct genetic background of landraces

Untangling the Relationship Between Antiretroviral Therapy Use and Incident Pregnancy: A Marginal Structural Model Analysis Using Data From 47,313 HIV-Positive Women in East Africa

BACKGROUND: Scale-up of triple-drug antiretroviral therapy (ART) in Africa has transformed the context of childbearing for HIV-positive women and may impact pregnancy incidence in HIV programs. METHODS: Using observational data from 47,313 HIV-positive women enrolled at 26 HIV clinics in Kenya and Uganda between 2001 and 2009, we calculated the crude cumulative incidence of pregnancy for the pre-ART and on-ART periods. The causal effect of ART use on incident pregnancy was assessed using inverse probability weighted marginal structural models, and the relationship was further explored in multivariable Cox models. RESULTS: Crude cumulative pregnancy incidence at 1 year after enrollment/ART initiation was 4.0% and 3.9% during the pre-ART and on-ART periods, respectively. In marginal structural models, ART use was not significantly associated with incident pregnancy [hazard ratio = 1.06; 95% confidence interval (CI): 0.99 to 1.12]. Similarly, in Cox models, there was no significant relationship between ART use and incident pregnancy (cause-specific hazard ratio: 0.98; 95% CI: 0.91 to 1.05), but effect modification was observed. Specifically, women who were pregnant at enrollment and on ART had an increased risk of incident pregnancy compared to those not pregnant at enrollment and not on ART (cause-specific hazard ratio: 1.11; 95% CI: 1.01 to 1.23). CONCLUSIONS: In this large cohort, ART initiation was not associated with incident pregnancy in the general population of women enrolling in HIV care but rather only among those pregnant at enrollment. This finding further highlights the importance of scaling up access to lifelong treatment for pregnant women