1,414 research outputs found
High dose multiple micronutrient supplementation improves villous morphology in environmental enteropathy without HIV enteropathy: results from a double-blind randomised placebo controlled trial in Zambian adults
PMCID: PMC3897937This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated
A Comparative Study of Reservoir Computing for Temporal Signal Processing
Reservoir computing (RC) is a novel approach to time series prediction using
recurrent neural networks. In RC, an input signal perturbs the intrinsic
dynamics of a medium called a reservoir. A readout layer is then trained to
reconstruct a target output from the reservoir's state. The multitude of RC
architectures and evaluation metrics poses a challenge to both practitioners
and theorists who study the task-solving performance and computational power of
RC. In addition, in contrast to traditional computation models, the reservoir
is a dynamical system in which computation and memory are inseparable, and
therefore hard to analyze. Here, we compare echo state networks (ESN), a
popular RC architecture, with tapped-delay lines (DL) and nonlinear
autoregressive exogenous (NARX) networks, which we use to model systems with
limited computation and limited memory respectively. We compare the performance
of the three systems while computing three common benchmark time series:
H{\'e}non Map, NARMA10, and NARMA20. We find that the role of the reservoir in
the reservoir computing paradigm goes beyond providing a memory of the past
inputs. The DL and the NARX network have higher memorization capability, but
fall short of the generalization power of the ESN
Seed maturation and drying in sweet corn (Zea mays L.) endosperm mutants
Incorporation of high sugar endosperm mutants into sweet corn genotypes has altered the carbohydrate composition of the resultant kernels which exhibit high post-harvest sugar retention and extended shelf life. However, acceptance of these genotypes has been limited because of problems associated with reductions in seed viability and seedling vigor and increased susceptibility to soil pathogens;The objective of this study was to characterize the physiological differences in seed viability and vigor associated with drying temperature and stage of maturity, and to determine the relationships between kernel soluble sugars during maturation and subsequent seed quality in sweet corn endosperm mutants;Seed of three genotypes, Jubilee (su), Sucro (sh2), and a genotype with the se gene, was harvested over a range of moisture contents during five harvests at 4-day intervals beginning 35 days after pollination. Ears were dried at 35, 40 and 45 C to 12% moisture. Seed viability was determined by the warm germination test, while the cold germination test, shoot to root ratio, and germination test after soaking seeds were used as indicators of vigor. Leachate conductivity was measured to indicate membrane integrity. Soluble sugars of embryos and endosperms obtained from fresh kernels at successive stages of maturity and from seed leachate, were separated by high performance liquid chromatography;Sweet corn seed exhibited a protracted period of high moisture retention throughout maturation. Seed moisture was poorly correlated with seed viability (r = -0.52) and seedling vigor (r = -0.46). Seedling vigor was more a function of genotype while seed viability varied with genotype, maturity, and drying temperatures. The se-genotype exhibited superior viability and vigor as compared with Jubilee and Sucro. Kernel maturity had less effect on electrolyte leakage than did drying temperature and genotype. Sucro exhibited the greatest rate of leakage when conductivity was read at 6, 12, and 24 h after soaking seeds. High seed quality was obtained when seed was dried at 35 C;The se-genotype exhibited the highest ratio of embryo sucrose to total sucrose and ratios of maltose and raffinose to sucrose. It is suggested that these ratios may play a role in membrane integrity during maturation drying and during imbibition and subsequent germination
Estudio geofÃsico de la corteza oceánica de la Cuenca Canaria (Atlántico Centro-Oriental)
[ES] El estudio combinado de datos de sÃsmica de reflexión de multicanal y de monocanal permite conocer la estructura de la corteza oceánica de la Cuenca Canaria y relacionarla con la historia de la expansión del fondo oceánico y las principales estructuras tectónicas formadas durante el Mesozoico en el Atlántico Central.[EN] The combined study of single and multi-channel seismic reflection data allow us to understand the structure of the Canary Basin oceanic crust and their relationship with the seafloor spreading history and main tectonic features formed during Mesozoic times on the Central Atlantic.Este trabajo es parte del estudio llevado a cabo por
C.R. Ranero, bajo la dirección de E Banda, en el Instituto
de Ciencias de la Tierra "Jaume Almera" del CSIC
para la obtención del grado de Doctor. C.R. Ranero recibió
financiación durante su estancia en el Instituto de
Ciencias de la Tierra mediante unsi beca de "Formació
d'Investigadors de el "Departament d'Ensenyament de la
Generalitat de Catalunya".Peer reviewe
A knowledge-based expert system for scheduling of airborne astronomical observations
The Kuiper Airborne Observatory Scheduler (KAOS) is a knowledge-based expert system developed at NASA Ames Research Center to assist in route planning of a C-141 flying astronomical observatory. This program determines a sequence of flight legs that enables sequential observations of a set of heavenly bodies derived from a list of desirable objects. The possible flight legs are constrained by problems of observability, avoiding flyovers of warning and restricted military zones, and running out of fuel. A significant contribution of the KAOS program is that it couples computational capability with a reasoning system
HIV infection and domestic smoke exposure, but not human papillomavirus, are risk factors for esophageal squamous cell carcinoma in Zambia: a case-control study
(c) 2015 The Authors. Cancer Medicine published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited
Mechanism of salinity change and hydrogeochemical evolution of groundwater in the Machile-Zambezi Basin, South-western Zambia
Machile-Zambezi Basin, South-Western Zambia hosts high salinity groundwater which threatens water security for rural inhabitants. This study investigates the hydrological mechanism that led to high salinity and the geochemical evolution of the groundwater system. The Machile-Zambezi Basin is part of the wider Kalahari Basin which underwent major palaeo-environmental climatic, tectonic and sedimentology dynamics which must have impacted the groundwater salinity. The study examines the groundwater level, hydrochemistry, environmental isotopes (18O/16O, 2H/1H, 3H/3He, 14C/13C). In addition, the sediment cation exchange capacity (CEC) and pore-water chemistry on intact core material were measured. The groundwater chemistry evolved from fresh Ca(Na)HCO3 to saline Na(Ca, Mg)SO4 due to dissolution of salts and not evaporation as indicated by stable isotopes. The saline groundwater is old with 14C ages estimates of more than 1000 years old and stagnant. Geochemical modelling using PHREEQC suggests that ionic exchange due to release of cations from dissolving salts and sulphate reduction were also important processes in this system. High groundwater salinity is therefore associated with Pre-Holocene environmental changes and is restricted to a stagnant saline zone. It will therefore remain unflushed as long as current climatic conditions remain
Ultrasound potentialities on the determination of the pesticide carbaryl using diamond electrodes
The potentiality of the use of ultrasound radiation in association with a boron-doped diamond electrode was evaluated on the voltammetric determination of the pesticide carbaryl. Improvements in the sensitivity, limit of detection and reproducibility of the measurements were observed due to both, the enhancement of mass transport and the cleaning of the electrode surface provided by ultrasound. Satisfactory recovery levels for carbaryl in pure water (96-98%) and pineapple juice (89-92%) for quiescent and sonovoltammetric methodologies were obtained. These methodologies can be alternative tools for the analyses of pesticides in fruit samples, mainly the insonated condition that improve the analytical performance and dispense intermediary cleanings of the electrode surface.CNPqFapes
Prevalence of clinical, immunological and irological failure among children on Haart at the university teaching hospital, Lusaka, Zambia
Background: There is increasing evidence that the current clinical and immunological monitoring tools are not sufficient to identify early enough patients who are failing on treatment. Development of resistance to the limited treatment options for children and premature switching are the dangers. The objective of this study was to review patient records to see how well WHO staging, CD4 profiles and viral load estimations relate in children on treatment at the University Teaching Hospital (UTH).Methods: A retrospective chart review of all children aged between 0-19 years that started treatment between January 2004 and Dec 2010 was carried out at the UTH. Systematic sampling was done of every second child who received HAART for more than 24 weeks, with at least one viral load (VL) reading beyond 24 weeks of treatment. Six-monthly clinical (WHO staging) immunological (age- related CD4 count/%) and virological data were collected until last follow-up review or five years on treatment. The 2010 Zambian Pediatric Guidelines were used to gauge age-related clinical, immunological and virological failure (VL> 1,000).Results: A total of 517 patient records were reviewed (table 1). Mean age at ART initiation was 7 years ((SD 4.7yrs). Mean time after ART initiation when first viral load test was done was 2.7 years (SD 1.5yrs). Of all the viral loads done, 64% (328) had a routine indication for patients on treatment nearing the 3 year mark (mean 2.7 years). In 40% of children the first viral load test result was above 1,000 after 24 weeks or more of treatment. A total of 482 patients had WHO staging done at the time first VL test was done. Of the 359 patients (table 2) with a clinical stage I/II (not severely immunosuppressed), 41% were failing virologically. On the other hand, 63% of the patients with clinical stage III/IV had a VL below 1,000. Table 3 shows that there were 509 patients who had an immunological staging done at the time first VL was done. Of the 106 patients who were failing immunologically, 28% were virologically well suppressed. On the other hand of the 403 who were immunologically doing fine, 32% were failing virologically.Conclusions: Clinical staging and Immunological monitoring in children on ART does not accurately identify those that are failing. A push for routine, affordable virological testing is needed to identify treatment failures early to prevent development of ART resistance and to avoid premature switches to second line in those who are actually well suppressed
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