Experimental observation of defect pair separation triggering phase transitions

First-order phase transitions typically exhibit a significant hysteresis resulting for instance in boiling retardation and supercooling. The hysteresis arises, because nucleation of the new phase is activated. The free-energy change is positive until the nucleus reaches a critical size beyond which further growth is downhill. In practice, the barrier is often circumvented by the presence of heterogeneous nucleation centres, e. g. at vessel walls or seed crystals. Recently, it has been proposed that the homogeneous melting of ice proceeds via separation of defect pairs with a substantially smaller barrier as compared to the mere aggregation of defects. Here we report the observation of an analogous mechanism catalysing a two-dimensional homogeneous phase transition. A similar process is believed to occur in spin systems. This suggests that separation of defect pairs is a common trigger for phase transitions. Partially circumventing the activation barrier it reduces the hysteresis and may promote fluctuations within a temperature range increasing with decreasing dimensionality

Economic evaluation of short treatment for multidrugresistant tuberculosis, Ethiopia and South Africa : the STREAM trial

OBJECTIVE STREAM was a phase-III non-inferiority randomised controlled trial (RCT) to evaluate a shortened regimen for multi-drug resistant tuberculosis (MDR-TB), and included the first-ever within-trial economic evaluation of such regimens, reported here. METHODS We compared the costs of ‘Long’ (20-22 months) and ‘Short’ (9-11 months) regimens in Ethiopia and South Africa. Cost data were collected from trial participants, and health system costs estimated using ‘bottom-up’ and ‘top-down’ costing approaches. A cost-effectiveness analysis was conducted with the trial primary outcome as the measure of effectiveness, including a probabilistic sensitivity analysis (PSA) to illustrate decision uncertainty. FINDINGS The Short-regimen reduced healthcare costs per case by 21% in South Africa (US$8,341 Long vs US$6,619 Short) and 25% in Ethiopia (US$6,097 Long vs US$4,552 Short). The largest component of this saving was medication in South Africa (67%) and social support in Ethiopia (35%). In Ethiopia, participants on the Short-regimen reported reductions in dietary supplementation expenditure (US$225 per case (95$13 (95%CI 11-14), South Africa US$64 (95$19,000 (Ethiopia) or <US$14,500 (South Africa). CONCLUSION The Short-regimen provided substantial health system cost savings and reduced financial burden on participants. Shorter regimens are likely to be cost-effective in most settings, and an effective strategy to support the WHO goal of eliminating catastrophic costs in T

Climbing depth-bounded adjacent discrepancy search for solving hybrid flow shop scheduling problems with multiprocessor tasks

This paper considers multiprocessor task scheduling in a multistage hybrid flow-shop environment. The problem even in its simplest form is NP-hard in the strong sense. The great deal of interest for this problem, besides its theoretical complexity, is animated by needs of various manufacturing and computing systems. We propose a new approach based on limited discrepancy search to solve the problem. Our method is tested with reference to a proposed lower bound as well as the best-known solutions in literature. Computational results show that the developed approach is efficient in particular for large-size problems

Barriers to accessing TB diagnosis for rural-to-urban migrants with chronic cough in Chongqing, China: A mixed methods study

<p>Abstract</p> <p>Background</p> <p>China is facing a significant tuberculosis epidemic among rural-to-urban migrants, which poses a threat to TB control. This study aimed to understand the health seeking behaviour of and health systems responses to migrants and permanent urban residents suffering from chronic cough, in order to identify the factors influencing delays for both groups in receiving a TB diagnosis in urban China.</p> <p>Methods</p> <p>Combining a prospective cohort study of adult suspect TB patients and a qualitative study, the Piot model was used to analyze the health seeking behaviour of TB suspects among migrants and permanent urban residents, the factors influencing their decision and the responses by general health providers. Methods included a patient survey, focus group discussions with migrants in the general population, qualitative interviews with migrant and permanent resident TB suspects and TB patients as well as key stakeholders related to TB control and the management of migrants.</p> <p>Results</p> <p>Sixty eight percent of migrants delayed for more than two weeks before seeking care for symptoms suggestive of TB, compared to 54% of residents (p < 0.01). When they first decided to seek professional care, migrants were 1.5 times more likely than residents to use less expensive, community-level health services. Only 5% were ultimately referred to a TB dispensary. Major reasons for both patient and provider delay included lack of knowledge and mistrust of the TB control programme, lack of knowledge about TB (patients), and profit-seeking behaviour (providers). In the follow up survey, 61% of the migrants and 41% of the residents who still had symptoms gave up continuing to seek professional care, with a statistically significant difference between the two groups (p < 0.05).</p> <p>Conclusion</p> <p>Rural-to-urban migrants are more likely than permanent residents to delay in seeking care for symptoms suggestive of TB in urban Chongqing. 'Patient-' and 'provider-' related factors interact to pose barriers to TB diagnosis for migrants, including: low awareness, and poor knowledge among both the general public and TB suspects about TB as a disease and about the TB control programme; low financial capacity to pay for care and diagnostic tests; and inadequate use of diagnostic tests and referral to TB dispensaries by general health providers.</p

African Trypanosomiasis in Travelers Returning to the United Kingdom

Two returning safari tourists with African trypanosomiasis were admitted to the Hospital for Tropical Diseases, London, in a 3-day period, compared with six cases in the previous 14 years. We describe the clinical features, diagnosis, and problems encountered in accessing appropriate therapy, and discuss the potential for emergence of this disease in increasingly adventurous international travelers

Assessment of the patient, health system, and population eff ects of Xpert MTB/RIF and alternative diagnostics for tuberculosis in Tanzania: an integrated modelling approach

Background Several promising new diagnostic methods and algorithms for tuberculosis have been endorsed by WHO. National tuberculosis programmes now face the decision on which methods to implement and where to place them in the diagnostic algorithm. Methods We used an integrated model to assess the eff ects of diff erent algorithms of Xpert MTB/RIF and lightemitting diode (LED) fl uorescence microscopy in Tanzania. To understand the eff ects of new diagnostics from the patient, health system, and population perspective, the model incorporated and linked a detailed operational component and a transmission component. The model was designed to represent the operational and epidemiological context of Tanzania and was used to compare the eff ects and cost-eff ectiveness of diff erent diagnostic options. Findings Among the diagnostic options considered, we identifi ed three strategies as cost eff ective in Tanzania. Full scale-up of Xpert would have the greatest population-level eff ect with the highest incremental cost: 346 000 disability-adjusted life-years (DALYs) averted with an additional cost of US$36·9 million over 10 years. The incremental cost-eff ectiveness ratio (ICER) of Xpert scale-up ($169 per DALY averted, 95% credible interval [CrI] 104–265) is below the willingness-to-pay threshold ($599) for Tanzania. Same-day LED fl uorescence microscopy is the next most eff ective strategy with an ICER of$45 (95% CrI 25–74), followed by LED fl uorescence microscopy with an ICER of $29 (6–59). Compared with same-day LED fl uorescence microscopy and Xpert full rollout, targeted use of Xpert in presumptive tuberculosis cases with HIV infection, either as an initial diagnostic test or as a followon test to microscopy, would produce DALY gains at a higher incremental cost and therefore is dominated in the context of Tanzania. Interpretation For Tanzania, this integrated modelling approach predicts that full rollout of Xpert is a cost-eff ective option for tuberculosis diagnosis and has the potential to substantially reduce the national tuberculosis burden. It also estimates the substantial level of funding that will need to be mobilised to translate this into clinical practice. This approach could be adapted and replicated in other developing countries to inform rational health policy formulation

Quantifying the need for enhanced case management for TB patients as part of TB cohort audit in the North West of England: a descriptive study

Abstract Background Patients with TB have diverse and often challenging clinical and social needs that may hamper successful treatment outcomes. Understanding the need for additional support during treatment (enhanced case management, or ECM) is important for workforce capacity planning. North West England TB Cohort Audit (TBCA) has introduced a 4-level ECM classification system (ECM 0–3) to quantify the need for ECM in the region. This study describes the data from the first 2 years of ECM classification. Methods Data collected between April 2013 and July 2015 were used to analyse the proportions of patients allocated to each ECM level and the prevalence of social and clinical factors indicating need for ECM. Single variable and multivariable logistic regression models were constructed to examine the association between ECM level and treatment outcome. Results Of 1714 notified cases 99.8% were assigned an ECM level: 31% ECM1, 19% ECM2 and 14% ECM3. The most common factors indicating need for ECM were language barriers (20.3%) and clinical complexity (16.9%). 1342/1493 (89.9%) of drug-sensitive, non-CNS cases completed treatment within 12 months. Patients in ECM2 and 3 were less likely to complete treatment at 12 months than patients in ECM0 (adjusted OR 0.47 [95% CI 0.27–0.84] and 0.23 [0.13–0.41] respectively). Conclusions Use of TBCA to quantify different levels of need for ECM is feasible and has demonstrated that social and clinical complexity is common in the region. Results will inform regional workforce planning and assist development of innovative methods to improve treatment outcomes in these vulnerable groups

Risk for Tuberculosis among Children

Risk among children is underestimated in countries with a high incidence of this disease

Model study of adsorbed metallic quantum dots: Na on Cu(111)

We model electronic properties of the second monolayer Na adatom islands (quantum dots) on the Cu(111) surface covered homogeneously by the first Na monolayer. An axially-symmetric three-dimensional jellium model, taking into account the effects due to the first Na monolayer and the Cu substrate, has been developed. The electronic structure is solved within the local-density approximation of the density-functional theory using a real-space multigrid method. The model enables the study of systems consisting of thousands of Na-atoms. The results for the local density of states are compared with differential conductance ($dI/dV$) spectra and constant current topographs from Scanning Tunneling Microscopy.Comment: 10 pages, 8 figures. For better quality figures, download http://www.fyslab.hut.fi/~tto/cylart1.pd