Robust Inference of Trees

This paper is concerned with the reliable inference of optimal tree-approximations to the dependency structure of an unknown distribution generating data. The traditional approach to the problem measures the dependency strength between random variables by the index called mutual information. In this paper reliability is achieved by Walley's imprecise Dirichlet model, which generalizes Bayesian learning with Dirichlet priors. Adopting the imprecise Dirichlet model results in posterior interval expectation for mutual information, and in a set of plausible trees consistent with the data. Reliable inference about the actual tree is achieved by focusing on the substructure common to all the plausible trees. We develop an exact algorithm that infers the substructure in time O(m^4), m being the number of random variables. The new algorithm is applied to a set of data sampled from a known distribution. The method is shown to reliably infer edges of the actual tree even when the data are very scarce, unlike the traditional approach. Finally, we provide lower and upper credibility limits for mutual information under the imprecise Dirichlet model. These enable the previous developments to be extended to a full inferential method for trees.Comment: 26 pages, 7 figure

Process Evaluation of a Clustered Randomized Control Trial of a Comprehensive Intervention to Reduce the Risk of Cardiovascular Events in Primary Health Care in Rural China

Background: Cardiovascular disease (CVD) is a major public health challenge in CBackground: Cardiovascular disease (CVD) is a major public health challenge in China. This study aims to understand the processes of implementing a comprehensive intervention to reduce CVD events in areas of drug therapy, lifestyle changes, and adherence support in a clustered randomized controlled trial (cRCT). This trial consisted of 67 clusters spanning over 3 years in Zhejiang Province, China. Method: A qualitative process evaluation was nested within the cRCT conducted in 9 township hospitals with 27 healthcare providers, 18 semi-structured interviews, and 23 observational studies of clinical practices within the intervention arm. Results: Effective and repeated trainings using an interactive approach were crucial to improve the prescribing behaviour of family doctors and their patient communication skills. However, the awareness of patients remained limited, thus compromising their use of CVD preventive drugs and adoption of healthy lifestyles. Health system factors further constrained providers’ and patients’ responses to the intervention. Financial barrier was a major concern because of the low coverage of health insurance. Other barriers included limited doctor–patient trust and suboptimal staff motivation. Conclusion: Our study suggests the feasibility of implementing a comprehensive CVD risk reduction strategy in China’s rural primary care facilities. However, health system barriers need to be addressed to ensure the success and sustainability of the intervention.hina. This study aims to understand the processes of implementing a comprehensive intervention to reduce CVD events in areas of drug therapy, lifestyle changes, and adherence support in a clustered randomized controlled trial (cRCT). This trial consisted of 67 clusters spanning over 3 years in Zhejiang Province, China. Method: A qualitative process evaluation was nested within the cRCT conducted in 9 township hospitals with 27 healthcare providers, 18 semi-structured interviews, and 23 observational studies of clinical practices within the intervention arm. Results: Effective and repeated trainings using an interactive approach were crucial to improve the prescribing behaviour of family doctors and their patient communication skills. However, the awareness of patients remained limited, thus compromising their use of CVD preventive drugs and adoption of healthy lifestyles. Health system factors further constrained providers’ and patients’ responses to the intervention. Financial barrier was a major concern because of the low coverage of health insurance. Other barriers included limited doctor–patient trust and suboptimal staff motivation. Conclusion: Our study suggests the feasibility of implementing a comprehensive CVD risk reduction strategy in China’s rural primary care facilities. However, health system barriers need to be addressed to ensure the success and sustainability of the intervention.</jats:p

Patterns of antihypertensive prescribing, discontinuation and switching among a Hong Kong Chinese population from over one million prescriptions

Hypertension is an alarming public health problem among Chinese. The present study evaluated the prescribing patterns, discontinuation and switching profiles of antihypertensive agents and their associated factors in one Hong Kong Chinese population. Data were retrieved from computerized records for patients prescribed anti-hypertensive agents in government primary care clinics of Hong Kong from January, 2004 to June, 2007. A total of 1,069,836 antihypertensive drug visits, representing 67,028 patients, were analyzed. The most commonly prescribed drugs were Calcium Channel Blockers (CCBs) (49%), b-Blockers (BBs) (46%) and Angiotensin-Converting Enzyme Inhibitors (ACEIs) (19%). Thiazide diuretic prescribing was low (13%) and on the decline (14% in 2004 to 12% in 2007). Prescribing of ACEIs was rising (16% in 2004 to 23% in 2007). Patients’ age, gender, and socio-economic status were independent predictors of class of anti-hypertensive prescribed but explained less than 3.5% of the variation observed. Drug discontinuation was highest for BBs (21%) and lowest for CCBs (12%). The high rates of discontinuation in BBs remained apparent after controlling for confounding variables. Switching was less common than discontinuation and was most likely with thiazide diuretics. To summarize, prescribing of CCBs and BBs were high and that of thiazide diuretics particularly low in this Chinese population when compared with international trends. CCBs may be a particularly favorable antihypertensive treatment in Chinese, given the high discontinuation rates of BBs and international guidelines advising against the use of BBs as first-line therapy. The low use of thiazide diuretics warrants further clinical and cost effectiveness studies among Chinese

Particle size effect on strength, failure and shock behavior in Polytetrafluoroethylene-Al-W granular composites

The variation of metallic particle size and sample porosity significantly alters the dynamic mechanical properties of high density granular composites processed using a cold isostatically pressed mixture of polytetrafluoroethylene (PTFE), aluminum (Al) and tungsten (W) powders. Quasi-static and dynamic experiments are performed with identical constituent mass fractions with variations in the size of the W particles and pressing conditions. The relatively weak polymer matrix allows the strength and fracture modes of this material to be governed by the granular type behavior of agglomerated metal particles. A higher ultimate compressive strength was observed in relatively high porosity samples with small W particles compared to those with coarse W particles in all experiments. Mesoscale granular force chains comprised of the metallic particles explain this unusual phenomenon as observed in a hydrocode simulation of a drop-weight test. Macrocracks forming below the critical failure strain for the matrix and unusual behavior due to a competition between densification and fracture in dynamic tests of porous samples were also observed. Shock loading of this granular composite resulted in higher fraction of total internal energy deposition in the soft PTFE matrix, specifically thermal energy, which can be tailored by the W particle size distribution.Comment: 35 pages, 13 figure

Implementation of a comprehensive intervention for patients at high risk of cardiovascular disease in rural China: A pragmatic cluster randomized controlled trial

Objective: This study aims to assess whether a standard intervention package of cardiovascular disease (CVD) care was being delivered effectively, and if it was associated with improved lifestyle and biomedical indicators. Methods: In rural China, we implemented a pragmatic cluster randomized controlled trial for 12 months, randomized at the township hospital level, and compared with usual care. Intervention case management guideline, training and performance monitoring meeting and patient support activities were designed to fit within the job description of family doctors in the township hospitals and comprised: 1) prescription of a standardised package of medicines targeted at those with hypertension or diabetes; 2) advice about specific lifestyle interventions; and 3) advice about medication adherence. Participants were 50-74 years old, had hypertension and CVD risk scores >20% or diabetes, but were excluded if a history of severe CVD events. We also randomly selected 100 participants from six selected clusters per arm as a panel to collect intermediate biomedical indicators over time. Results: A total of 28,130 participants, in 33 intervention and 34 control township hospitals, were recruited. Compared with the control arm, participants in the intervention arm had substantially improved prescribing rates of anti-hypertensives, statins and aspirin (P0.05). Conclusion: Implementation of the package by family doctors was feasible and improved prescribing and some lifestyle changes. Additional measures such as reducing medication costs and patient education are required. Trial registration: Current Controlled Trials ISRCTN58988083

Further evidence for the involvement of EFL1 in a Shwachman-Diamond-like syndrome and expansion of the phenotypic features.

Recent evidence has implicated EFL1 in a phenotype overlapping Shwachman-Diamond syndrome (SDS), with the functional interplay between EFL1 and the previously known causative gene SBDS accounting for the similarity in clinical features. Relatively little is known about the phenotypes associated with pathogenic variants in the EFL1 gene, but the initial indication was that phenotypes may be more severe, when compared with SDS. We report a pediatric patient who presented with a metaphyseal dysplasia and was found to have biallelic variants in EFL1 on reanalysis of trio whole-exome sequencing data. The variant had not been initially reported because of the research laboratory's focus on de novo variants. Subsequent phenotyping revealed variability in her manifestations. Although her metaphyseal abnormalities were more severe than in the original reported cohort with EFL1 variants, the bone marrow abnormalities were generally mild, and there was equivocal evidence for pancreatic insufficiency. Despite the limited number of reported patients, variants in EFL1 appear to cause a broader spectrum of symptoms that overlap with those seen in SDS. Our report adds to the evidence of EFL1 being associated with an SDS-like phenotype and provides information adding to our understanding of the phenotypic variability of this disorder. Our report also highlights the value of exome data reanalysis when a diagnosis is not initially apparent

Effects of financial incentives for treatment supporters on tuberculosis treatment outcomes in Swaziland: a pragmatic interventional study

Background: Swaziland has the highest national incidence of tuberculosis (TB) in the world, with treatment success rates well below the 85 % international target. Treatment support as part of comprehensive TB services is a core component of the Stop TB Strategy. This study investigated the effects of financial incentives for treatment supporters on TB treatment outcomes in Swaziland. Methods: This was a controlled study that compared treatment outcomes for patients with a treatment supporter who received or did not receive a financial incentive. Results: The intervention group had a higher chance of treatment success as compared with the control group: 73 % (95 % confidence intervals [CIs] 66–80 %) versus 60 % (95 % CIs 57–64 %), respectively, p = 0.003. This improvement remained significant when treatment success rates were adjusted for differences in baseline characteristics, with the effect of incentivised treatment supporters on treatment outcomes having an odds ratio (OR) of 1.8. There was also a significant improvement in the death rate in the intervention group, as compared with the control group (10.6 versus 23.5 %, p = <0.001). Conclusion: Incentives provided to TB treatment supporters appear to significantly improve TB treatment outcomes. Incentivising treatment support may be appropriate as an effective addition to support and supervision measures (199 words)

Borehole plugging materials development program, report 2

The data for 2 yr of grout mixtures durability studies developed for the borehole plugging program of the Nuclear Waste Isolation Pilot Plant (WIPP) are reported. In addition, data for 1 yr of durability studies of grout mixture field samples used to plug the ERDA No. 10 exploratory drill hole near the WIPP site are included. The grout samples and the data do not show any evidence of deterioration during the durability studies that include exposure to brine at both ambient and elevated temperatures. The data include strength, compressional wave velocity, dynamic modulus, expansion, weight change, porosity, permeability, bond strength, chemical analysis of cements, and petrographic examinations. The work was performed at the Concrete Division of the Structures Laboratory of the US Army Engineer Waterways Experiments Station (WES), Vicksburg, Mississippi. The work is continuing at WES

Correlates of Snake Entanglement in Erosion Control Blankets

In road construction projects across the United States, erosion control methods (e.g., erosion control blankets [ECBs]), are mandated to stimulate seedbed regeneration and prevent soil loss. Previous reports have suggested that snakes are vulnerable to entanglement in ECBs. We conducted a literature review, field surveys, and an entanglement experiment to examine what factors increase a snake’s risk of ECB entanglement. Our literature review produced reports of 175 reptiles entangled in mesh products, 89.1% of which were snakes, with 43.6% of snake entanglements occurring in erosion control products. During our field surveys, we found 10 entangled snakes (n = 2 alive; n = 8 dead). From our experiment, we found that ECBs that contain fixed‐intersection, small‐diameter mesh consisting of polypropylene were significantly more likely to entangle snakes compared with ECBs with larger diameter polypropylene mesh or ECBs that have woven mesh made of natural fibers. Snake body size was also associated with entanglement; for every 1‐mm increase in body circumference, the probability of entanglement increased 4%. These results can help construct a predictive framework to determine those species and individuals that are most vulnerable to entanglement