272 research outputs found

    Design and Evaluation of a Pressure Based Typing Biometric Authentication System

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    The design and preliminary evaluation of a pressure sensor-based typing biometrics authentication system (PBAS) is discussed in this paper. This involves the integration of pressure sensors, signal processing circuit, and data acquisition devices to generate waveforms, which when concatenated, produce a pattern for the typed password. The system generates two templates for typed passwords. First template is for the force applied on each password key pressed. The second template is for latency of the password keys. These templates are analyzed using two classifiers. Autoregressive (AR) classifier is used to authenticate the pressure template. Latency classifier is used to authenticate the latency template. Authentication is complete by matching the results of these classifiers concurrently. The proposed system has been implemented by constructing users’ database patterns which are later matched to the biometric patterns entered by each user, thereby enabling the systemto accept or reject the user. Experiments have been conducted to test the performance of the overall PBAS system and results obtained showed that this proposed system is reliable with many potential applications for computer security

    Successful Conservative Management of Scrotal Edema Resulting from Uncomplicated Peritoneal Fluid Leak

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    Introduction: Peritoneal fluid leaks are frequent in continuous ambulatory peritoneal dialysis (CAPD) patients and may manifest as subcutaneous or genital edema or as apparent ultrafiltration (UF) failure. Genital swelling in CAPD patients is often due to dialysate leak through a small clinically-undetectable inguinal hernia, and may require herniorrhaphy. If imaging studies exclude an associated hernia or patent processus vaginalis, a conservative approach may be adopted. Case report: An 80 year-old bed-ridden male developed gross bilateral scrotal swelling (without cough impulse) and apparent UF failure shortly after initiation of CAPD. Computed tomography peritoneography (CTP) showed bilateral scrotal fluid collections without a hernia or patent processus vaginalis. An attempt to maintain the patient on CAPD by reducing the dialysate volume, scrotal elevation and adopting a supine position was not successful; CAPD was substituted with temporary hemodialysis (HD) for four weeks. Scrotal swelling reversed after one week of CAPD cessation and did not recur when supine PD with intermittent dry periods was reinstituted a few weeks later. Satisfactory UF could also be easily attained. This was compatible with caudal fluid migration through peritoneal defects being the underlying cause. The patient had been successfully maintained on CAPD for the last 18 months. Conclusion: Fluid dissection through soft tissues can result in gross genital edema and apparent ultrafiltration failure in CAPD patients. Supine PD, scrotal elevation with intermittent dry periods may be a practical alternative management in the absence of automated dialysis facilities. The severity of dialysate leak does not preclude a satisfactory response to this conservative management. Keywords: peritoneal dialysis, dialysate leak, genital edema, ultrafiltration failur

    Development of forest structure and leaf area in secondary forests regenerating on abandoned pastures in Central Amazonia

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    The area of secondary forest (SF) regenerating from pastures is increasing in the Amazon basin; however, the return of forest and canopy structure following abandonment is not well understood. This study examined the development of leaf area index (LAI), canopy cover, aboveground biomass, stem density, diameter at breast height (DBH), and basal area ( BA) by growth form and diameter class for 10 SFs regenerating from abandoned pastures. Biomass accrual was tree dominated, constituting >= 94% of the total measured biomass in all forests abandoned >= 4 to 6 yr. Vine biomass increased with forest age, but its relative contribution to total biomass decreased with time. The forests were dominated by the tree Vismia spp. (> 50%). Tree stem density peaked after 6 to 8 yr ( 10 320 stems per hectare) before declining by 42% in the 12- to 14-yr-old SFs. Small-diameter tree stems in the 1-5-cm size class composed > 58% of the total stems for all forests. After 12 to 14 yr, there was no significant leaf area below 150-cm height. Leaf area return (LAI = 3.2 after 12 to 14 yr) relative to biomass was slower than literature-reported recovery following slash-and-burn, where LAI can reach primary forest levels ( LAI = 4 - 6) in 5 yr. After 12 to 14 yr, the colonizing vegetation returned some components of forest structure to values reported for primary forest. Basal area and LAI were 50% - 60%, canopy cover and stem density were nearly 100%, and the rapid tree-dominated biomass accrual was 25% - 50% of values reported for primary forest. Biomass accumulation may reach an asymptote earlier than expected because of even-aged, monospecific, untiered stand structure. The very slow leaf area accumulation relative to biomass and to reported values for recovery following slash-and-burn indicates a different canopy development pathway that warrants further investigation of causes ( e. g., nutrient limitations, competition) and effects on processes such as evapotranspiration and soil water uptake, which would influence long-term recovery rates and have regional implications

    Y Chromosome Lineage- and Village-Specific Genes on Chromosomes 1p22 and 6q27 Control Visceral Leishmaniasis in Sudan

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    Familial clustering and ethnic differences suggest that visceral leishmaniasis caused by Leishmania donovani is under genetic control. A recent genome scan provided evidence for a major susceptibility gene on Chromosome 22q12 in the Aringa ethnic group in Sudan. We now report a genome-wide scan using 69 families with 173 affected relatives from two villages occupied by the related Masalit ethnic group. A primary ten-centimorgan scan followed by refined mapping provided evidence for major loci at 1p22 (LOD score 5.65; nominal p = 1.72 × 10(−7); empirical p < 1 × 10(−5); λ(S) = 5.1) and 6q27 (LOD score 3.74; nominal p = 1.68 × 10(−5); empirical p < 1 × 10(−4); λ(S) = 2.3) that were Y chromosome–lineage and village-specific. Neither village supported a visceral leishmaniasis susceptibility gene on 22q12. The results suggest strong lineage-specific genes due to founder effect and consanguinity in these recently immigrant populations. These chance events in ethnically uniform African populations provide a powerful resource in the search for genes and mechanisms that regulate this complex disease

    Blood Parasite Load as an Early Marker to Predict Treatment Response in Visceral Leishmaniasis in Eastern Africa

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    Background: To expedite the development of new oral treatment regimens for visceral leishmaniasis (VL), there is a need for early markers to evaluate treatment response and predict long-term outcomes. Methods: Data from 3 clinical trials were combined in this study, in which Eastern African VL patients received various antileishmanial therapies. Leishmania kinetoplast DNA was quantified in whole blood with real-time quantitative polymerase chain reaction (qPCR) before, during, and up to 6 months after treatment. The predictive performance of pharmacodynamic parameters for clinical relapse was evaluated using receiver-operating characteristic curves. Clinical trial simulations were performed to determine the power associated with the use of blood parasite load as a surrogate endpoint to predict clinical outcome at 6 months. Results: The absolute parasite density on day 56 after start of treatment was found to be a highly sensitive predictor of relapse within 6 months of follow-up at a cutoff of 20 parasites/mL (area under the curve 0.92, specificity 0.91, sensitivity 0.89). Blood parasite loads correlated well with tissue parasite loads (ρ = 0.80) and with microscopy gradings of bone marrow and spleen aspirate smears. Clinical trial simulations indicated a > 80% power to detect a difference in cure rate between treatment regimens if this difference was high (> 50%) and when minimally 30 patients were included per regimen. Conclusions: Blood Leishmania parasite load determined by qPCR is a promising early biomarker to predict relapse in VL patients. Once optimized, it might be useful in dose finding studies of new chemical entities.This work was supported by the European Union Seventh Framework Programme Africoleish (grant number 305178); the World Health Organization—Special Programme for Research and Training in Tropical Diseases (WHO-TDR); the French Development Agency, France (grant number CZZ2062); UK aid, UK; the Federal Ministry of Education and Research through KfW, Germany; the Medicor Foundation, Liechtenstein; Médecins Sans Frontières, International; the Swiss Agency for Development and Cooperation (SDC), Switzerland (grant number 81017718); the Dutch Ministry of Foreign Affairs (DGIS), the Netherlands (grant number PDP15CH21); the French Ministry for Europe and Foreign Affairs (MEAE), France; The Rockefeller Foundation, USA; BBVA Foundation, Spain; the European Union—AfriKADIA project of the Second European and Developing Countries Clinical Trials Partnership Programme (EDCTP2) (grant number RIA2016S1635); and ZonMw/Dutch Research Council (NWO) Veni grant (project number 91617140 to T. P. C. D.).S

    Single-dose liposomal amphotericin B (AmBisome®) for the treatment of Visceral Leishmaniasis in East Africa: study protocol for a randomized controlled trial

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    BACKGROUND: AmBisome® is an efficacious, safe anti-leishmanial treatment. There is growing interest in its use, either as a single dose or in combination treatments. In East Africa, the minimum optimal single-dosage has not been identified. METHODS/DESIGN: An open-label, 2-arm, non-inferiority, multi-centre randomised controlled trial is being conducted to determine the optimal single-dose treatment with AmBisome®.Patients in the single-dose arm will receive one infusion on day 1, at a dose depending on body weight. For the first group of patients entered to the trial, the dose will be 7.5 mg/kg, but if this dose is found to be ineffective then in subsequent patient series the dose will be escalated progressively to 10, 12.5 and 15 mg/kg. Patients in the reference arm will receive a multi-dose regimen of AmBisome® (3 mg/kg/day on days 1-5, 14 and 21: total dose 21 mg/kg). Patients will be hospitalised for approximately one month after the start of treatment and then followed up at three and six months. The primary endpoint is the status of patients six months after treatment. A secondary endpoint is assessment at day 30. Treatment success is determined as the absence of parasites on microscopy samples taken from bone marrow, lymph node or splenic aspirates. Interim analyses to assess the comparative efficacy of the single dose are planned after recruitment of 20 and 40 patients per arm. The final non-inferiority analysis will include 120 patients per arm, to determine if the single-dose efficacy 6 months after treatment is not more than 10% inferior to the multi-dose. DISCUSSION: An effective, safe single-dose treatment would reduce hospitalization and treatment costs. Results will inform the design of combination treatment studies. TRIAL REGISTRATION: ClinicalTrials.gov NCT00832208

    Uncertainty in modeled and observed climate change impacts on American Midwest hydrology

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    An important potential consequence of climate change is the modification of the water cycle in agricultural areas, such as the American Midwest. Soil moisture is the integrand of the water cycle, reflecting dynamics of precipitation, evapotranspiration, and runoff in space and time, and a key determinant of yield. Here we present projected changes in the hydrologic cycle over a representative area of the American Midwest from regional climate model experiments that sample a range of model configurations. While significant summer soil moisture drying is predicted in some ensemble members, others predict soil moisture wetting, with the sign of soil moisture response strongly influenced by choice of boundary conditions. To resolve the contradictory predictions of soil moisture across ensemble members, we assess an extensive and unique observational data set of the water budget in Illinois. No statistically significant monotonic trends are found in observed soil moisture, precipitation, streamflow, groundwater level, or 2 m air temperature over a recent 26 year period (soil moisture 25 years). Based on this analysis of model simulations and observations, we conclude that the sign of climate change impacts on the regional hydrology of the American Midwest remains uncertain.National Science Foundation (U.S.

    Hydropower plans in eastern and southern Africa increase risk of concurrent climate-related electricity supply disruption

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    Hydropower comprises a significant and rapidly expanding proportion of electricity production in eastern and southern Africa. In both regions, hydropower is exposed to high levels of climate variability and regional climate linkages are strong, yet an understanding of spatial interdependences is lacking. Here we consider river basin configuration and define regions of coherent rainfall variability using cluster analysis to illustrate exposure to the risk of hydropower supply disruption of current (2015) and planned (2030) hydropower sites. Assuming completion of the dams planned, hydropower will become increasingly concentrated in the Nile (from 62% to 82% of total regional capacity) and Zambezi (from 73% to 85%) basins. By 2030, 70% and 59% of total hydropower capacity will be located in one cluster of rainfall variability in eastern and southern Africa, respectively, increasing the risk of concurrent climate-related electricity supply disruption in each region. Linking of nascent regional electricity sharing mechanisms could mitigate intraregional risk, although these mechanisms face considerable political and infrastructural challenges
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