759 research outputs found
Effect of dose rate on ion beam mixing in Nb-Si
The influence of dose rate, i.e., ion flux, on ion beam mixing in NbâSi bilayer samples was measured at room temperature and 325â°C. At the higher temperature, an increase in dose rate of a factor of 20 caused a decrease in the thickness of the mixed layer by a factor of 1.6 for equal total doses. At room temperature, the same change in flux had no effect on mixing. These results are consistent with radiationâenhanced diffusion theory in the recombinationâlimited regime
Correlation between the cohesive energy and the onset of radiation-enhanced diffusion in ion mixing
A correlation between the cohesive energy of elemental solids and the characteristic temperature Tc for the onset of radiation-enhanced diffusion during ion mixing is established. This correlation enables one to predict the onset of radiation-enhanced diffusion for systems which have not yet been investigated. A theoretical argument based on the current models of cascade mixing and radiation-enhanced diffusion is provided as a basis for understanding this observation
New methods for the synthesis of certain alkaloids and terpenoids
The use of ring-fused gem-dihalocyclopropanes, Au(I)-catalyzed cyclization reactions, and chemoenzymatic techniques in the synthesis of natural products is described.We thank the Australian Research Council for generous financial support through the provision of various
grants
Malaria burden and costs of intensifi ed control in Bhutan, 2006â14: an observational study and situation analysis
Introduction The number of malaria cases has fallen in Bhutan in the past two decades, and the country has a goal of
complete elimination of malaria by 2016. The aims of this study are to ascertain the trends and burden of malaria, the
costs of intensifi ed control activities, the main donors of funding for the control activities, and the costs of diff erent
preventive measures in the pre-elimination phase (2006â14) in Bhutan.
Methods We undertook a descriptive analysis of malaria surveillance data from 2006 to 2014, using data from the
Vector-borne Disease Control Programme (VDCP) run by the Department of Public Health of Bhutanâs Ministry of
Health. Malaria morbidity and mortality in local Bhutanese people and foreign nationals were analysed. The cost of
diff erent control and preventive measures were calculated, and the average numbers of long-lasting insecticidal nests
per person were estimated.
Findings A total of 5491 confi rmed malaria cases occurred in Bhutan between 2006 and 2014. By 2013, there was an
average of one long-lasting insecticidal net for every 1¡51 individuals. The cost of procuring long-lasting insecticidal
nets accounted for more than 90% of the total cost of prevention measures. The Global Fund to Fight AIDS,
Tuberculosis and Malaria was the main international donor, accounting for more than 80% of the total funds.
Interpretation The malaria burden in Bhutan decreased signifi cantly during the study period with high coverage of
long-lasting insecticidal nets. The foreseeable challenges that require national attention to maintain a malaria-free
status after elimination are importation of malaria, especially from India; continued protection of the population in
endemic districts through complete coverage with long-lasting insecticidal nets and indoor residual spraying; and
exploration of local funding modalities post-elimination in the event of a reduction in international funding
Development and evaluation of a spatial decision support system for malaria elimination in Bhutan
BACKGROUND:
Bhutan has reduced its malaria incidence significantly in the last 5Â years, and is aiming for malaria elimination by 2016. To assist with the management of the Bhutanese malaria elimination programme a spatial decision support system (SDSS) was developed. The current study aims to describe SDSS development and evaluate SDSS utility and acceptability through informant interviews.
METHODS:
The SDSS was developed based on the open-source Quantum geographical information system (QGIS) and piloted to support the distribution of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) in the two sub-districts of Samdrup Jongkhar District. It was subsequently used to support reactive case detection (RACD) in the two sub-districts of Samdrup Jongkhar and two additional sub-districts in Sarpang District. Interviews were conducted to ascertain perceptions on utility and acceptability of 11 informants using the SDSS, including programme and district managers, and field workers.
RESULTS:
A total of 1502 households with a population of 7165 were enumerated in the four sub-districts, and a total of 3491 LLINs were distributed with one LLIN per 1.7 persons. A total of 279 households representing 728 residents were involved with RACD. Informants considered that the SDSS was an improvement on previous methods for organizing LLIN distribution, IRS and RACD, and could be easily integrated into routine malaria and other vector-borne disease surveillance systems. Informants identified some challenges at the programme and field level, including the need for more skilled personnel to manage the SDSS, and more training to improve the effectiveness of SDSS implementation and use of hardware.
CONCLUSIONS:
The SDSS was well accepted and informants expected its use to be extended to other malaria reporting districts and other vector-borne diseases. Challenges associated with efficient SDSS use included adequate skills and knowledge, access to training and support, and availability of hardware including computers and global positioning system receivers
Supraglacial lakes on the Larsen B ice shelf, Antarctica, and at Paakitsoq, West Greenland:A Comparative Study
This is the accepted manuscript. The final version is available from Ingenta Connect at http://www.ingentaconnect.com/content/igsoc/agl/2014/00000055/00000066/art00001.Supraglacial meltwater lakes trigger ice-shelf break-up and modulate seasonal ice\ud
sheet flow, and are thus agents by which warming is transmitted to the Antarctic\ud
and Greenland ice sheets. To characterize supraglacial lake variability we perform a\ud
comparative analysis of lake geometry and depth in two distinct regions, one on the\ud
pre-collapse (2002) Larsen B Ice Shelf, and the other in the ablation zone of\ud
Paakitsoq, a land-terminating region of the Greenland Ice Sheet. Compared to\ud
Paakitsoq, lakes on the Larsen B Ice Shelf cover a greater proportion of surface area\ud
(5.3% vs. 1%), but are shallower and more uniform in area. Other aspects of lake\ud
geometry, such as eccentricity, degree of convexity (solidity) and orientation, are\ud
relatively similar between the two regions. We attribute the notable difference in\ud
lake density and depth between ice-shelf and grounded ice to the fact that ice shelves\ud
have flatter surfaces and less distinct drainage basins. Ice shelves also possess more\ud
stimuli to small-scale, localized surface elevation variability due to the various\ud
structural features that yield small variations in thickness and which float at\ud
different levels by Archimedes? principle.We acknowledge the support of the U.S. National Science Foundation under grant ANT-0944248
Podoconiosis and soil-transmitted helminths (STHs): double burden of neglected tropical diseases in Wolaita zone, rural southern Ethiopia
Background
Both podoconiosis and soil-transmitted helminth (STH) infections occur among barefoot people in areas of extreme poverty; however, their co-morbidity has not previously been investigated. We explored the overlap of STH infection and podoconiosis in Southern Ethiopia and quantified their separate and combined effects on prevalent anemia and hemoglobin levels in podoconiosis patients and health controls from the same area.
Methods and Principal Findings
A two-part comparative cross-sectional study was conducted in Wolaita zone, southern Ethiopia. Data were collected from adult patients presenting with clinically confirmed podoconiosis, and unmatched adult neighborhood controls living in the same administrative area. Information on demographic and selected lifestyle factors was collected using interviewer-administered questionnaires. Stool samples were collected and examined qualitatively using the modified formalin-ether sedimentation method. Hemoglobin level was determined using two different methods: hemoglobinometer and automated hematology analyzer. A total of 913 study subjects (677 podoconiosis patients and 236 controls) participated. The prevalence of any STH infection was 47.6% among patients and 33.1% among controls (p<0.001). The prevalence of both hookworm and Trichuris trichiura infections was significantly higher in podoconiosis patients than in controls (AOR 1.74, 95% CI 1.25 to2.42, AOR 6.53, 95% CI 2.34 to 18.22, respectively). Not wearing shoes and being a farmer remained significant independent predictors of infection with any STH. There was a significant interaction between STH infection and podoconiosis on reduction of hemoglobin level (interaction p value = 0.002).
Conclusions
Prevalence of any STH and hookworm infection was higher among podoconiosis patients than among controls. A significant reduction in hemoglobin level was observed among podoconiosis patients co-infected with hookworm and ânon-hookworm STHâ. Promotion of consistent shoe-wearing practices may have double advantages in controlling both podoconiosis and hookworm infection in the study area
Validation of a score tool for measurement of histological severity in juvenile dermatomyositis and association with clinical severity of disease.
OBJECTIVES: To study muscle biopsy tissue from patients with juvenile dermatomyositis (JDM) in order to test the reliability of a score tool designed to quantify the severity of histological abnormalities when applied to biceps humeri in addition to quadriceps femoris. Additionally, to evaluate whether elements of the tool correlate with clinical measures of disease severity. METHODS: 55 patients with JDM with muscle biopsy tissue and clinical data available were included. Biopsy samples (33 quadriceps, 22 biceps) were prepared and stained using standardised protocols. A Latin square design was used by the International Juvenile Dermatomyositis Biopsy Consensus Group to score cases using our previously published score tool. Reliability was assessed by intraclass correlation coefficient (ICC) and scorer agreement (Îą) by assessing variation in scorers' ratings. Scores from the most reliable tool items correlated with clinical measures of disease activity at the time of biopsy. RESULTS: Inter- and intraobserver agreement was good or high for many tool items, including overall assessment of severity using a Visual Analogue Scale. The tool functioned equally well on biceps and quadriceps samples. A modified tool using the most reliable score items showed good correlation with measures of disease activity. CONCLUSIONS: The JDM biopsy score tool has high inter- and intraobserver agreement and can be used on both biceps and quadriceps muscle tissue. Importantly, the modified tool correlates well with clinical measures of disease activity. We propose that standardised assessment of muscle biopsy tissue should be considered in diagnostic investigation and clinical trials in JDM
A preliminary study of the effect of closed incision management with negative pressure wound therapy over high-risk incisions
Background
Certain postoperative wounds are recognised to be associated with more complications than others and may be termed high-risk. Wound healing can be particularly challenging following high-energy trauma where wound necrosis and infection rates are high. Surgical incision for joint arthrodesis can also be considered high-risk as it requires extensive and invasive surgery and postoperative distal limb swelling and wound dehiscence are common. Recent human literature has investigated the use of negative pressure wound therapy (NPWT) over high-risk closed surgical incisions and beneficial effects have been noted including decreased drainage, decreased dehiscence and decreased infection rates. In a randomised, controlled study twenty cases undergoing distal limb high-energy fracture stabilisation or arthrodesis were randomised to NPWT or control groups. All cases had a modified Robert-Jones dressing applied for 72 h postoperatively and NPWT was applied for 24 h in the NPWT group. Morphometric assessment of limb circumference was performed at six sites preoperatively, 24 and 72 h postoperatively. Wound discharge was assessed at 24 and 72 h. Postoperative analgesia protocol was standardised and a Glasgow Composite Measure Pain Score (GCPS) carried out at 24, 48 and 72 h. Complications were noted and differences between groups were assessed.
Results
Percentage change in limb circumference between preoperative and 24 and 72 h postoperative measurements was significantly less at all sites for the NPWT group with exception of the joint proximal to the surgical site and the centre of the operated bone at 72 h. Median discharge score was lower in the NPWT group than the control group at 24 h. No significant differences in GCPS or complication rates were noted.
Conclusions
Digital swelling and wound discharge were reduced when NPWT was employed for closed incision management. Larger studies are required to evaluate whether this will result in reduced discomfort and complication rates postoperatively
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