631 research outputs found

    Characterizing of some hydrochemical parameters of Tigris River, Iraq, with the aid of GIS

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    Nine stations along Tigris River in Iraq were selected to study the spatial and temporal changes of some selected parameters for the period 2009-2012. These parameters include discharge, Total Dissolved Solids,(TDS),NO3,BOD and COD. Water type is of bicarbonate along the northern stations (Feshkhabour, Mosul, Sharkat and Samarra) and transforms into sulfate in the remaining central and southern stations. GIS was used to characterize the temporal and spatial changes of these parameters along the selected River Tigris stations. Discharges values of all stations show significant temporal decreasing patterns and spatial decreasing patterns along these stations were also noticed. TDS values show noticeable temporal changes for the present stations, whereas sharp increasing changes downstream direction were observed. NO3, BOD and COD spatial and temporal changes show that their values show no indication on pollution and that their values for the high and low flow conditions are within the normal range values. Keywords, discharge, water type, GIS, spatial analyses, temporal change, Tigris River, Ira

    Thermoviscoplastic modelling of asymmetric effects for polymers at large strains

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    AbstractGlassy polymers such as polycarbonate exhibit different behaviours in different loading scenarios, such as tension and compression. To this end a flow rule is postulated within a thermodynamic consistent framework in a mixed variant formulation and decomposed into a sum of weighted stress mode related quantities. The different stress modes are chosen such that they are accessible to individual examination in the laboratory, where tension and compression are typical examples. The characterisation of the stress modes is obtained in the octahedral plane of the deviatoric stress space in terms of the Lode angle, such that stress mode dependent scalar weighting functions can be constructed. Furthermore the numerical implementation of the constitutive equations into a finite element program is briefly described. In a numerical example, the model is used to simulate the laser transmission welding process

    Assessment of Socio-economic and Environmental Impacts of Sand Mining: A case study of Dodoma City Council.

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    The purpose of the study is to identify factors contributing to sand mining, examining the environmental effects, examining forms of socio-economic effects, analyze the measures taken by the Dodoma City Council to mitigate the impacts of sand mining in the study area. Data were collected using techniques involving structured and unstructured questionnaires. Observations and group discussions. A sample of 100 was used, data were analyzed manually and using computer programme like statistical package for social sciences (SPSS) where by tables and photographs were used to present data. The result of the study indicate that the environment has been affected negatively by over 50% in the study area due to sand mining, the negative impacts also outweigh positive impacts of environment. Sand mining despite the fact that it provides temporary employment-The major mitigation measure taken by Dodoma City Council is planting of trees in the study area. Based on recommendations of this study, the major recommendation is authorities should conduct Environmental Impact Assessment (EIA) and monitoring sites to control damage the environment. However, this study some recommendations were provided such as National Environment Management Council should work closely with Dodoma City Council on monitoring the sand mining activities and this is because there is a link between the two authorities. Miners should refill pits after mining, and they should also seek permission from interested and affected communities before mining, changing mining sites to reduce over extraction. Keywords: Sand mining, environmental effects, socio-economic effects, Dodoma City Counci

    Assessment of linear-scale indices for perimetry in terms of progression in early glaucoma

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    AbstractCurrently, global indices that summarize the visual field combine sensitivities on a logarithmic (decibel) scale. Recent structure–function models for glaucoma suggest that contrast sensitivity should be converted to a linear scale before averaging across visual field locations, to better relate sensitivity with the number of surviving retinal ganglion cells (RGCs). New indices designed to represent the number of RGCs already lost are described. At least one was found to be a significantly better predictor of subsequent rate of change than traditional Mean Deviation (p=0.014) in participants with glaucomatous optic neuropathy. Issues concerning the creation of optimal global indices are discussed

    A mitigation of channel crosstalk effect in dispersion shifted fiber based on durability of modulation technique

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    In fiber optics the Four Wave Mixing (FWM) has the harmful effect of an optical transmission system that can severely limit Wavelength Division Multiplexing (WDM) and reduce the transmission aptness. This work preset the durability of the different modulation format was tested to FWM by using Dispersion Shifted Fiber (DSF). Moreover, the performance of the proposed system is surveyed by changing the fiber length and applying an information rate of 200 Gb/s. The experimental results show that the FWM capacity has decreased significantly by more than 14 dB when applying Return to Zero (RZ) modulation form. In addition, in terms of the propsed system performance in the first channel and with 700 km distance, it was observed that the lower Bit Error Rate (BER) in the normal RZ modulation is equal to 1.3×10-13. As well as it is noticeable when applied the Non Return to Zero (NRZ), the Modified Duobinary Return to Zero (MDRZ) and Gaussian modulation, the system performance will be quickly changed and getting worse, where the BERs increased to 1.3×10-4, 1.3×10-6 and 1.3×10-2 consecutively at same channel and for the same parameters

    Improvement of Cell Wall Degrading Enzymes Production by Alginate Encapsulated Trichoderma spp.

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    Conidia of three Trichoderma isolates were formulated to make alginate pellets with or without 0.5 % chitin or dried fungal mycelium of Fusarium oxysporum as carbon source. The formulations were compared for their ability of in vitro chitinase and β-1,3-glucanase production with free fungal spore suspensions. Conidia entrapped in alginate with or without adjuvant showed high production of enzymes (especially for chitinase) even when repeated 4 times. The addition of chitin or dried fungal mycelium as adjuvant enhanced the enzyme production up to 5 and 2-fold for chitinase and β-1,3-glucanase, respectively. Alginate concentration and surface area of the beads affected the enzyme production. The optimum initial pH, incubation time and temperature were pH=6, 12 days and 40 °C for chitinase, and pH=7, 10 days and 35 °C for β-1,3-glucanase production. The improvement of cell wall degrading enzyme production by alginate encapsulated Trichoderma could explain the in vivo inhibitory effect of such formulations on the target phytopathogenic fungi

    Very strong intrinsic supercurrent carrying ability and vortex avalanches in (Ba,K)Fe2As2 superconducting single crystals

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    We report that single crystals of (Ba,K)Fe2As2 with Tc = 32 K have a pinning potential, U0, as high as 10^4 K, with U0 showing very little field depend-ence. In addition, the (Ba,K)Fe2As2 single crystals become isotropic at low temperatures and high magnetic fields, resulting in a very rigid vortex lattice, even in fields very close to Hc2. The rigid vortices in the two dimensional (Ba,K)Fe2As2 distinguish this compound from 2D high Tc cuprate superconductors with 2D vortices, and make it being capable of cearrying very high critical current.Flux jumping due to high Jc was also observed in large samples at low temperatures.Comment: 4 pages, 7 figures. submitte

    Relationship of Omega-3 Fatty Acids on C-Reactive Protein and Homocysteine in Haitian and African Americans with and without Type 2 Diabetes

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    Background: Omega-3 fatty acids (n-3) may be protective of cardiovascular risk factors for vulnerable populations. The purpose of this study was to assess the association between n-3 with, C-reactive protein (CRP), and homocysteine (HCY) in Black minorities with and without type 2 diabetes. Methods: A cross-sectional study was conducted with 406 participants: Haitian Americans (HA): n=238. African Americans (AA): n=172. Participants were recruited from a randomly generated mailing lists, local diabetes educators, community health practitioners and advertisements from 2008-2010. Sociodemographics and anthropometrics were collected and used to adjust analyses. All dietary variables were collected using the semi-quantitative food frequency questionnaire (FFQ) and used to quantify vitamin components. Blood was collected to measure CVD risk factors (blood lipids, HCY, and CRP). Results: African Americans had higher waist circumferences and C-reactive protein and consumed more calories as compared to Haitian Americans. Omega 3 fatty acid intake per calorie did not differ between these ethnicities, yet African Americans with low n-3 intake were three times more likely to have high C-reactive protein as compared to their counterparts [OR=3. 32 (1. 11, 9. 26) p=0.031]. Although homocysteine did not differ by ethnicity, African Americans with low omega 3 intake (\u3c1 g/day) were four times as likely to have high homocysteine (\u3e12 mg/L) as compared to their counterparts, adjusting for confounders [OR=4.63 (1.59, 12.0) p=0.004]. Consumption of n-3 by diabetes status was not associated with C-reactive protein or homocysteine levels. Conclusions: Consumption of n-3 may be protective of cardiovascular risk factors such as C-
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