126 research outputs found

    Towards supplier maturity evaluation in terms of PLM collaboration

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    The product lifecycle management (PLM) system has a significant role to support the collaboration and manage the partnership between OEM and Supplier to enable the success of supplier integration. Today great rates of co- operation as suppliers have been dedicated to SMEs. Since one of the PLM task is to control the collaboration between OEM and suppliers, this paper provide supplier (SMEs) a framework to find their place in this relationship in the concept of PLM. To respond to this trend, we defined a methodology based on collaborative matrix maturity levels and four PLM axes of strategic, organization, process and tools levels. Finally according to this ma- trix, we proposed a structure of a proper questionnaire and example that show suppliers how to evaluate their positions in terms of collaboration in PLM

    Microbiological Implications of Periurban Agriculture and Water Reuse in Mexico City

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    BACKGROUND: Recycled treated or untreated wastewater represents an important health challenge in developing countries due to potential water related microbiological exposure. Our aim was to assess water quality and health implications in a Mexico City periurban agricultural area. METHODOLOGY/PRINCIPAL FINDINGS: A longitudinal study in the Xochimilco wetland area was conducted, and 42 sites were randomly selected from 211, including irrigation water canals and effluents of treatment plants. Sample collection took place during rainy and dry seasons (2000-2001). Microbiological parameters (total coliforms, fecal coliforms, streptococci/enterococci, and bacteria other than Vibrio grown on TCBS), Helicobacter pylori, and physicochemical parameters including trihalomethanes (THM) were determined. Fecal coliforms and fecal streptococci are appropriate indicators of human or animal fecal contamination. Fecal coliform counts surpass Mexican and World Health Organization irrigation water guidelines. Identified microorganisms associated with various pathologies in humans and domestic animals comprise Escherichia coli, Klebsiella spp., Salmonella spp., Enterobacter spp., Enterococcus spp., and Pseudomonas spp; H. pylori was also present in the water. An environmental characteristic of the canal system showed high Total Organic Carbon content and relatively low dissolved oxygen concentration; residual chlorine as a disinfection control is not efficient, but THMs do not represent a problem. During the rainy season, temperature and conductivity were higher; in contrast, pH, dissolved oxygen, ammonia, and residual chlorine were lower. This is related with the continuous load of feces from human and animal sources, and to the aquatic systems, which vary seasonally and exhibit evidence of lower water quality in effluents from treatment plants. CONCLUSIONS/SIGNIFICANCE: There is a need for improvement of wastewater treatment systems, as well as more efficient monitoring, regulation, and enforcement procedures for wastewater disposal into bodies of water

    Randomized clinical trial of percutaneous transluminalangioplasty, supervised exercise and combined treatment forintermittent claudication due to femoropopliteal arterial disease

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    Background:The aim was to compare percutaneous transluminal angioplasty (PTA), a supervisedexercise programme (SEP) and combined treatment (PTA plus SEP) for intermittent claudication dueto femoropopliteal arterial disease.Methods: Consenting patients with femoropopliteal arterial lesions were randomized to one of threetreatment arms: PTA, SEP, or PTA plus SEP. All patients received optimal medical treatment. Patientswere assessed at baseline and 1, 3, 6 and 12 months after intervention. Clinical (ankle pressures, walkingdistances, symptoms) and quality-of-life (QoL) outcomes (Short Form 36, VascuQol) were analysed.Results: A total of 178 patients (108 men, median age 70 years) were included. All three treatmentgroups demonstrated significant clinical and QoL improvements. One year after PTA (60 patients, 8withdrew), 37 patients (71 per cent) had improved (16 mild, 16 moderate, 5 marked), nine (17 per cent)showed no improvement and six (12 per cent) had deteriorated. After SEP (60 patients, 14 withdrew),32 patients (70 per cent) had improved (19 mild, 10 moderate, 3 marked), six (13 per cent) showed noimprovement and eight (17 per cent) had deteriorated. After PTA plus SEP (58 patients, 11 withdrew),40 patients (85 per cent) had improved (18 mild, 20 moderate, 2 marked), seven (15 per cent) showedno improvement and none had deteriorated. On intergroup analysis, PTA and SEP alone were equallyeffective in improving clinical outcomes, although the effect was short-lived. PTA plus SEP produced amore sustained clinical improvement, but there was no significant QoL advantage.Conclusion: For patients with intermittent claudication due to femoropopliteal disease, PTA, SEP,and PTA plus SEP were all equally effective in improving walking distance and QoL after 12 months.Registration number: NCT00798850 (http://www.clinicaltrials.gov)

    Systematic Study of Electron Localization in an Amorphous Semiconductor

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    We investigate the electronic structure of gap and band tail states in amorphous silicon. Starting with two 216-atom models of amorphous silicon with defect concentration close to the experiments, we systematically study the dependence of electron localization on basis set, density functional and spin polarization using the first principles density functional code Siesta. We briefly compare three different schemes for characterizing localization: information entropy, inverse participation ratio and spatial variance. Our results show that to accurately describe defect structures within self consistent density functional theory, a rich basis set is necessary. Our study revealed that the localization of the wave function associated with the defect states decreases with larger basis sets and there is some enhancement of localization from GGA relative to LDA. Spin localization results obtained via LSDA calculations, are in reasonable agreement with experiment and with previous LSDA calculations on a-Si:H models.Comment: 16 pages, 11 Postscript figures, To appear in Phys. Rev.

    Comparative study of enteric viruses, coliphages and indicator bacteria for evaluating water quality in a tropical high-altitude system

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    <p>Abstract</p> <p>Background</p> <p>Bacteria used as indicators for pathogenic microorganisms in water are not considered adequate as enteric virus indicators. Surface water from a tropical high-altitude system located in Mexico City that receives rainwater, treated and non-treated wastewater used for irrigation, and groundwater used for drinking, was studied.</p> <p>Methods</p> <p>The presence of enterovirus, rotavirus, astrovirus, coliphage, coliform bacteria, and enterococci was determined during annual cycles in 2001 and 2002. Enteric viruses in concentrated water samples were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). Coliphages were detected using the double agar layer method. Bacteria analyses of the water samples were carried out by membrane filtration.</p> <p>Results</p> <p>The presence of viruses and bacteria in the water used for irrigation showed no relationship between current bacterial indicator detection and viral presence. Coliphages showed strong association with indicator bacteria and enterovirus, but weak association with other enteric viruses. Enterovirus and rotavirus showed significant seasonal differences in water used for irrigation, although this was not clear for astrovirus.</p> <p>Conclusion</p> <p>Coliphages proved to be adequate faecal pollution indicators for the irrigation water studied. Viral presence in this tropical high-altitude system showed a similar trend to data previously reported for temperate zones.</p

    Antibody-Directed Lentiviral Gene Transduction for Live-Cell Monitoring and Selection of Human iPS and hES Cells

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    The identification of stem cells within a mixed population of cells is a major hurdle for stem cell biology–in particular, in the identification of induced pluripotent stem (iPS) cells during the reprogramming process. Based on the selective expression of stem cell surface markers, a method to specifically infect stem cells through antibody-conjugated lentiviral particles has been developed that can deliver both visual markers for live-cell imaging as well as selectable markers to enrich for iPS cells. Antibodies recognizing SSEA4 and CD24 mediated the selective infection of the iPS cells over the parental human fibroblasts, allowing for rapid expansion of these cells by puromycin selection. Adaptation of the vector allows for the selective marking of human embryonic stem (hES) cells for their removal from a population of differentiated cells. This method has the benefit that it not only identifies stem cells, but that specific genes, including positive and negative selection markers, regulatory genes or miRNA can be delivered to the targeted stem cells. The ability to specifically target gene delivery to human pluripotent stem cells has broad applications in tissue engineering and stem cell therapies
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