1,102 research outputs found
Influence of Timber Harvesting Operations and Streamside Management Zone Effectiveness on Sediment Delivery to Headwater Streams in Appalachia
Disturbances created by timber harvesting equipment and associated haul roads and skid trails can create overland sediment flows (sediment paths), especially in steeply sloping terrain, leading to stream sedimentation. This study investigated the effect of variables associated with GPS tracked harvest equipment movement, skid trail development and retirement, topography, and streamside management zone (SMZ) width and tree retention on sediment delivery to streams. While the intensity of harvest equipment traffic was not correlated with sediment path development, the presence and location of skid trails were. All of the sediment paths were found to originate at water control structures, influenced by microtopographic features, on the skid trails directly adjacent to SMZs. Mesic slopes were associated with increased sediment path development across all SMZ configurations. Two factors, the accumulation of coarse logging debris in the SMZ and the increased distance of skid trails to streams, were both correlated with decreased sediment path development. The study provides insight into how these variables interact and can be used to develop site-specific guidelines for SMZs in steeply sloping terrain that could improve their efficiency and effectiveness
Retroactive comparison of operator-designed and computer-generated skid-trail networks on steep terrain
Aim of the study: Quantify potential economic benefits of implementing computer-generated skid-trail networks over the traditional operator-designed skid-trail networks on steep terrain ground-based forest operations.Area of study: A 132-ha harvest operation conducted at the University of Kentucky’s Robinson Forest in eastern Kentucky, USA.Materials and methods: We compared computer-generated skid-trail network with an operator-designed network for a 132-ha harvest. Using equipment mounted GPS data and a digital elevation model (DEM), we identified the original operator-designed skid-trail network. Pre-harvest conditions were replicated by re-contouring terrain slopes over skid-trails to simulate the natural topography and by spatially distributing the harvestable volume based on pre-harvest inventories and timber harvest records. An optimized skid-trail network was designed using these pre-harvest conditions and compared to the original, operator-designed network.Main results: The computer-generated network length was slightly longer than the operator-designed network (53.7 km vs. 51.7 km). This also resulted in a slightly longer average skidding distance (0.71 km vs. 0.66 km) and higher total harvesting costs (5.1 ton-1). However, skidding costs of the computer-generated network were slightly lower (4.2 ton-1). When comparing only major skid-trails, those with ≥ 20 machine passes, the computer-generated skid-trail network was 28% shorter than the operator network (9.4 km vs. 13.1 km). Research highlight: This assessment offers evidence that computer-generated networks could be used to generate efficient skid-trails, help determine skidding costs, and assess further potential economic and environmental benefits.Key words: timber harvesting; forest operations; network optimization; soil disturbances; cost minimization
A retrospective study of HIV, antiretroviral therapy, and pregnancy-associated hypertension among women in Lusaka, Zambia
To investigate the association between HIV, antiretroviral therapy (ART), and pregnancy-associated hypertension (PAH) in an HIV-endemic setting
Predictors and outcomes of low birth weight in Lusaka, Zambia
To determine factors associated with low birth weight (LBW) in an urban Zambian cohort and investigate risk of adverse outcomes for LBW neonates
Modern Contraceptive and Dual Method Use among HIV-Infected Women in Lusaka, Zambia
HIV-infected women
in sub-Saharan Africa are at substantial risk of
unintended pregnancy and sexually transmitted
infections (STIs). Linkages between HIV and
reproductive health services are advocated. We
describe implementation of a reproductive health
counseling intervention in 16 HIV clinics in
Lusaka, Zambia. Between November 2009 and
November 2010, 18,407 women on antiretroviral
treatment (ART) were counseled. The median age
was 34.6 years (interquartile range (IQR):
29.9–39.7), and 60.1% of women were
married. The median CD4+ cell count
was 394 cells/uL (IQR: 256–558). Of
the women counseled, 10,904 (59.2%) reported
current modern contraceptive use. Among
contraceptive users, only 17.7% reported
dual method use. After counseling, 737 of 7,503
women not previously using modern contraception
desired family planning referrals, and 61.6%
of these women successfully accessed services
within 90 days. Unmet contraceptive need remains
high among HIV-infected women. Additional
efforts are needed to promote reproductive
health, particularly dual method
use
Point-of-Care Virologic Testing to Improve Outcomes of HIV-Infected Children in Zambia: A Clinical Trial Protocol
In the absence of early infant diagnosis (EID) and immediate antiretroviral therapy (ART), some 50% of untreated HIV-infected infants die before age 2. Conventional EID requires sophisticated instruments that are typically placed in centralized or reference laboratories. In low-resource settings, centralized systems often lead to result turnaround times of several months, long delays in diagnosis, and adverse outcomes for HIV-infected children. Our clinical trial tests the effectiveness of a new point-of-care (POC) diagnostic technology to identify HIV-infected infants and start providing them life-saving ART as soon as possible
Assessment of Streamside Management Zones for Conserving Benthic Macroinvertebrate Communities Following Timber Harvest in Eastern Kentucky Headwater Catchments
Headwater streams generally comprise the majority of stream area in a watershed and can have a strong influence on downstream food webs. Our objective was to determine the effect of altering streamside management zone (SMZ) configurations on headwater aquatic insect communities. Timber harvests were implemented within six watersheds in eastern Kentucky. The SMZ configurations varied in width, canopy retention and best management practice (BMP) utilization at the watershed scale. Benthic macroinvertebrate samples collected one year before and four years after harvest indicated few differences among treatments, although post-treatment abundance was elevated in some of the treatment streams relative to the unharvested controls. Jaccard index values were similar across SMZ treatments after logging, indicating strong community overlap. These findings suggest that stream invertebrate communities did respond to the timber harvest, though not negatively. Results also suggest that SMZ criteria for aquatic habitats in steeply sloping topography, including at least 50 percent canopy retention and widths of at least 16.8 m, appear to be adequate for protecting benthic macroinvertebrate communities from logging impacts
Temporal Trends and Predictors of Modern Contraceptive Use in Lusaka, Zambia, 2004-2011.
INTRODUCTION: Although increasing access to family planning has been an important part of the global development agenda, millions of women continue to face unmet need for contraception. MATERIALS AND METHODS: We analyzed data from a repeated cross-sectional community survey conducted in Lusaka, Zambia, over an eight-year period. We described prevalence of modern contraceptive use, including long-acting reversible contraception (LARC), among female heads of household aged 16-50 years. We also identified predictors of LARC versus short-term contraceptive use among women using modern methods. RESULTS AND DISCUSSION: Twelve survey rounds were completed between November 2004 and September 2011. Among 29,476 eligible respondents, 17,605 (60%) reported using modern contraception. Oral contraceptive pills remained the most popular method over time, but use of LARC increased significantly, from less than 1% in 2004 to 9% by 2011 (p < 0.001). Younger women (OR: 0.46, 95% CI: 0.34, 0.61) and women with lower levels of education (OR: 0.70, 95% CI: 0.56, 0.89) were less likely to report LARC use compared to women using short-term modern methods. CONCLUSIONS: Population-based assessments of contraceptive use over time can guide programs and policies. To achieve reproductive health equity and reduce unmet contraceptive need, future efforts to increase LARC use should focus on young women and those with less education
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