61 research outputs found

    Load Dependent Single Chain Models of Multichain Closed Queueing Networks

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    The Circulating Processor Model of Parallel Systems

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    This paper introduces the circulating processor model for parallel computer systems. The circulating processor model is a product form queuing network model where the processors are allowed to circulate between the parallel applications instead of the more traditional circulating task model. Certain behaviors of parallel systems are better captured using this new approach. The circulating processor model may be load dependent or load dependent. The load dependent circulating processor model is exact for systems which contain a single parallel application. An exact error is calculated for the load independent circulating processor model for systems which contain a single parallel application. The load dependent circulating processor model is a good approximation to the actual system in the case of multiple parallel applications. The load dependent circulating processor model compares favorably to the traditional circulating task model

    Hot in-place recycling of asphalt pavements.

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    http://archive.org/details/hotinplacerecycl00dow

    The Impact and Cost of Scaling up GeneXpert MTB/RIF in South Africa

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    We estimated the incremental cost and impact on diagnosis and treatment uptake of national rollout of Xpert MTB/RIF technology (Xpert) for the diagnosis of pulmonary TB above the cost of current guidelines for the years 2011 to 2016 in South Africa.We parameterised a population-level decision model with data from national-level TB databases (n = 199,511) and implementation studies. The model follows cohorts of TB suspects from diagnosis to treatment under current diagnostic guidelines or an algorithm that includes Xpert. Assumptions include the number of TB suspects, symptom prevalence of 5.5%, annual suspect growth rate of 10%, and 2010 public-sector salaries and drug and service delivery costs. Xpert test costs are based on data from an in-country pilot evaluation and assumptions about when global volumes allowing cartridge discounts will be reached.At full scale, Xpert will increase the number of TB cases diagnosed per year by 30%-37% and the number of MDR-TB cases diagnosed by 69%-71%. It will diagnose 81% of patients after the first visit, compared to 46% currently. The cost of TB diagnosis per suspect will increase by 55% to USD 60-61 and the cost of diagnosis and treatment per TB case treated by 8% to USD 797-873. The incremental capital cost of the Xpert scale-up will be USD 22 million and the incremental recurrent cost USD 287-316 million over six years.Xpert will increase both the number of TB cases diagnosed and treated and the cost of TB diagnosis. These results do not include savings due to reduced transmission of TB as a result of earlier diagnosis and treatment initiation

    Screening for Tuberculosis With Xpert MTB/RIF Assay Versus Fluorescent Microscopy Among Adults Newly Diagnosed With Human Immunodeficiency Virus in Rural Malawi: A Cluster Randomized Trial (Chepetsa).

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    BACKGROUND: Tuberculosis (TB) remains the leading cause of death among human immunodeficiency virus (HIV)-infected individuals globally. Screening for TB at the point of HIV diagnosis with a high-sensitivity assay presents an opportunity to reduce mortality. METHODS: We performed a cluster randomized trial of TB screening among adults newly diagnosed with HIV in 12 primary health clinics in rural Thyolo, Malawi. Clinics were allocated in a 1:1 ratio to perform either point-of-care Xpert MTB/RIF assay (Xpert) or point-of-care light-emitting diode fluorescence microscopy (LED-FM) for individuals screening positive for TB symptoms. Asymptomatic participants were offered isoniazid preventive therapy in both arms. Investigators, but not clinic staff or participants, were masked to allocation. Our primary outcome was the incidence rate ratio (RR) of all-cause mortality within 12 months of HIV diagnosis. RESULTS: Prevalent TB was diagnosed in 24 of 1001 (2.4%) individuals enrolled in clinics randomized to Xpert, compared with 10 of 841 (1.2%) in clinics randomized to LED-FM. All-cause mortality was 22% lower in the Xpert arm than in the LED-FM arm (6.7 vs 8.6 per 100 person-years; RR, 0.78 [95% confidence interval {CI}, .58-1.06]). A planned subgroup analysis suggested that participants with more advanced HIV (World Health Organization clinical stage 3 or 4) disease had lower mortality in clinics randomized to Xpert than to LED-FM (RR, 0.43 [95% CI, .22-.87]). CONCLUSIONS: In rural Malawi, using point-of-care Xpert MTB/RIF to test symptomatic patients for TB at the time of HIV diagnosis reduced all-cause 12-month mortality among individuals with advanced HIV. CLINICAL TRIALS REGISTRATION: NCT01450085

    Point of care Xpert MTB/RIF versus smear microscopy for tuberculosis diagnosis in southern African primary care clinics : a multicentre economic evaluation

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    CITATION: Pooran, A., et al. 2019. Point of care Xpert MTB/RIF versus smear microscopy for tuberculosis diagnosis in southern African primary care clinics : a multicentre economic evaluation. The Lancet Global Health, 7(6):E798-E807. doi:10.1016/S2214-109X(19)30164-0The original publication is available at https://www.thelancet.com/journals/langlo/homeBackground: Rapid on-site diagnosis facilitates tuberculosis control. Performing Xpert MTB/RIF (Xpert) at point of care is feasible, even when performed by minimally trained health-care workers, and when compared with point-of-care smear microscopy, reduces time to diagnosis and pretreatment loss to follow-up. However, whether Xpert is cost-effective at point of care remains unclear. Methods: We empirically collected cost (US,2014)andclinicaloutcomedatafromparticipantspresentingtoprimaryhealthcarefacilitiesinfourAfricancountries(SouthAfrica,Zambia,Zimbabwe,andTanzania)duringtheTBNEATtrial.Costsweredeterminedusinganbottomupingredientsapproach.Effectivenessmeasuresfromthetrialincludednumberofcasesdiagnosed,initiatedontreatment,andcompletingtreatment.TheprimaryoutcomewastheincrementalcosteffectivenessofpointofcareXpertrelativetosmearmicroscopy.Thestudywasperformedfromtheperspectiveofthehealthcareprovider.Findings:Usingdatafrom1502patients,wecalculatedthatthemeanXpertunitcostwaslowerwhenperformedatacentralisedlaboratory(LabXpert)ratherthanatpointofcare(, 2014) and clinical outcome data from participants presenting to primary health-care facilities in four African countries (South Africa, Zambia, Zimbabwe, and Tanzania) during the TB-NEAT trial. Costs were determined using an bottom-up ingredients approach. Effectiveness measures from the trial included number of cases diagnosed, initiated on treatment, and completing treatment. The primary outcome was the incremental cost-effectiveness of point-of-care Xpert relative to smear microscopy. The study was performed from the perspective of the health-care provider. Findings: Using data from 1502 patients, we calculated that the mean Xpert unit cost was lower when performed at a centralised laboratory (Lab Xpert) rather than at point of care (23·00 [95% CI 22·12–23·88] vs 2803[26192987]).Per1000patientsscreened,andrelativetosmearmicroscopy,pointofcareXpertcostanadditional28·03 [26·19–29·87]). Per 1000 patients screened, and relative to smear microscopy, point-of-care Xpert cost an additional 35 529 (27 054–40 025) and was associated with an additional 24·3 treatment initiations ([–20·0 to 68·5]; 1464pertreatment),634samedaytreatmentinitiations([273994];1464 per treatment), 63·4 same-day treatment initiations ([27·3–99·4]; 511 per same-day treatment), and 29·4 treatment completions ([–6·9 to 65·6]; 1211percompletion).Xpertcostsweremostsensitivetotestvolume,whereasincrementaloutcomesweremostsensitivetothenumberofpatientsinitiatingandcompletingtreatment.TheprobabilityofpointofcareXpertbeingcosteffectivewas901211 per completion). Xpert costs were most sensitive to test volume, whereas incremental outcomes were most sensitive to the number of patients initiating and completing treatment. The probability of point-of-care Xpert being cost-effective was 90% at a willingness to pay of 3820 per treatment completion. Interpretation: In southern Africa, although point-of-care Xpert unit cost is higher than Lab Xpert, it is likely to offer good value for money relative to smear microscopy. With the current availability of point-of-care nucleic acid amplification platforms (eg, Xpert Edge), these data inform much needed investment and resource allocation strategies in tuberculosis endemic settings.https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(19)30164-0/fulltextPublisher’s versio

    Communications Biophysics

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    Contains research objectives and reports on six research projects split into three sections.National Institutes of Health (Grant 5 P01 NS13126-07)National Institutes of Health (Training Grant 5 T32 NS07047-05)National Institutes of Health (Training Grant 2 T32 NS07047-06)National Science Foundation (Grant BNS 77-16861)National Institutes of Health (Grant 5 R01 NS1284606)National Institutes of Health (Grant 5 T32 NS07099)National Science Foundation (Grant BNS77-21751)National Institutes of Health (Grant 5 R01 NS14092-04)Gallaudet College SubcontractKarmazin Foundation through the Council for the Arts at M.I.T.National Institutes of Health (Grant 1 R01 NS1691701A1)National Institutes of Health (Grant 5 R01 NS11080-06)National Institutes of Health (Grant GM-21189

    Communications Biophysics

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    Contains reports on four research projects.National Institutes of Health (Grant 5 P01 NS13126-02)National Institutes of Health (Grant 5 K04 NS00113-03)National Institutes of Health (Grant 2 ROI NS11153-02A1)National Science Foundation (Grant BNS77-16861)National Institutes of Health (Grant 5 RO1 NS10916-03)National Institutes of Health (Fellowship 1 F32 NS05327)National Institutes of Health (Grant 5 ROI NS12846-02)National Institutes of Health (Fellowship 1 F32 NS05266)Edith E. Sturgis FoundationNational Institutes of Health (Grant 1 R01 NS11680-01)National Institutes of Health (Grant 2 RO1 NS11080-04)National Institutes of Health (Grant 5 T32 GIM107301-03)National Institutes of Health (Grant 5 TOI GM01555-10

    Communications Biophysics

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    Contains reports on ten research projects.National Institutes of Health (Grant 5 P01 NS13126)National Institutes of Health (Training Grant 5 T32 NS0704)National Science Foundation (Grant BNS80-06369)National Institutes of Health (Grant 5 R01 NS11153)National Science Foundation (Grant BNS77-16861)National Institutes of Health (Grant 5 RO1 NS12846)National Science Foundation (Grant BNS77-21751)National Institutes of Health (Grant 1 P01 NS14092)Karmazin Foundation through the Council for the Arts at MITNational Institutes of Health (Fellowship 5 F32 NS06386)National Science Foundation (Fellowship SP179-14913)National Institutes of Health (Grant 5 RO1 NS11080
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