53 research outputs found

    HLA Profile and Clinical Presentation of Multiple Sclerosis in Iran

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    Multiple sclerosis (MS) is a demyelinating disease of the central nervous system,with unknown etiology in which both genetic and environmental factors are thought to be involved. The HLA system provides a set of genetic markers which lend themselves to systematic study. The disease also has variable clinical manifestations, ranging from a relapsing-remitting course to a chronic progressive disease.In this article we review HLA profile and clinical presentation of the disease from current available data in Iran

    A steady-state saturation model to determine the subsurface travel time (STT) in complex hillslopes

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    The travel time of subsurface flow in complex hillslopes (hillslopes with different plan shape and profile curvature) is an important parameter in predicting the subsurface flow in catchments. This time depends on the hillslopes geometry (plan shape and profile curvature), soil properties and climate conditions. The saturation capacity of hillslopes affect the travel time of subsurface flow. The saturation capacity, and subsurface travel time of compound hillslopes depend on parameters such as soil depth, porosity, soil hydraulic conductivity, plan shape (convergent, parallel or divergent), hillslope length, profile curvature (concave, straight or convex) and recharge rate to the groundwater table. An equation for calculating subsurface travel time for all complex hillslopes was presented. This equation is a function of the saturation zone length (SZL) on the surface. Saturation zone length of the complex hillslopes was calculated numerically by using the hillslope-storage kinematic wave equation for subsurface flow, so an analytical equation was presented for calculating the saturation zone length of the straight hillslopes and all plan shapes geometries. Based on our results, the convergent hillslopes become saturated very soon and they showed longer SZL with shorter travel time compared to the parallel and divergent ones. The subsurface average flow rate in convergent hillslopes is much less than the divergent ones in the steady state conditions. Concerning to subsurface travel time, convex hillslopes have more travel time in comparison to straight and concave hillslopes. The convex hillslopes exhibit more average flow rate than concave hillslopes and their saturation capacity is very low. Finally, the effects of recharge rate variations, average bedrock slope and soil depth on saturation zone extension were investigated

    A Bayesian assessment of an approximate model for unconfined water flow in sloping layered porous media

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    The prediction of water table height in unconfined layered porous media is a difficult modelling problem that typically requires numerical simulation. This paper proposes an analytical model to approximate the exact solution based on a steady-state Dupuit–Forchheimer analysis. The key contribution in relation to a similar model in the literature relies in the ability of the proposed model to consider more than two layers with different thicknesses and slopes, so that the existing model becomes a special case of the proposed model herein. In addition, a model assessment methodology based on the Bayesian inverse problem is proposed to efficiently identify the values of the physical parameters for which the proposed model is accurate when compared against a reference model given by MODFLOW-NWT, the open-source finite-difference code by the U.S. Geological Survey. Based on numerical results for a representative case study, the ratio of vertical recharge rate to hydraulic conductivity emerges as a key parameter in terms of model accuracy so that, when appropriately bounded, both the proposed model and MODFLOW-NWT provide almost identical results

    Microwave processing of cement and concrete materials - towards an industrial reality?

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    Each year a substantial body of literature is published on the use of microwaves to process cement and concrete materials. Yet to date, very few if any have lead the realisation of a commercial scale industrial system and is the context under which this review has been undertaken. The state-of the–art is evaluated for opportunities, and the key barriers to the development of new microwave-based processing techniques to enhance production, processing and recycling of cement and concrete materials. Applications reviewed include pyro-processing of cement clinker; accelerated curing, non-destructive testing and evaluation (NDT&E), and end-of-life processing including radionuclide decontamination

    Rock, rap and ruckus at the Grammys

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    Modeling and training of hydraulic parameters affecting sedimentation

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    In this study, the numerical modeling of sediment washing in Sefidrood dam reservoir and its effect on reservoir volume recovery in the short and long term have been studied. For this purpose, the GSTARS 3 numerical model has been used to study the different phases of flashing. This model is prepared for free and pressurized sedimentation and each of them is analyzed separately. Studies on Sefidrood Dam show that due to the fact that the reservoir water level at the beginning of the flashing operation is one of the influential parameters in the efficiency of sediment washing efficiency, lowering the reservoir water level from normal (271 m) to the power plant (210) M) Reduces the water consumption from 897 cubic meters to 19 cubic meters for washing each ton of sediment. On the other hand, studies show that flashing does not affect coarse-grained sediments in this reservoir and cannot be used as the only solution to prevent reservoir depletion, and additional sedimentation operations such as dredging, use of siphons or In addition to annual sedimentation in the Sefidrud Dam reservoir, it is inevitable that heavy currents will flow through the reservoir.Sen

    Advanced Nonlinear Dynamic Analysis of Arch Dams considering Joints Effects

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    Influence of joints behavior on arch dams operation during the earthquakes is investigated. The case study is the Karun-1 double curvature arch dam with the height of 200 meters. The arch dam-foundation-reservoir systems are modeled with and without joints and estimate the effects of contraction and lift joints on stresses and displacements response histories for assessing the earthquake performance. According to nolinear dynamical analysis results, inclusion of the contraction and lift joints considerably influenced the dam response

    Multi-objective optimization for combined quality–quantity urban runoff control

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    Urban development affects the quantity and quality of urban surface runoff. In recent years, the best management practices (BMPs) concept has been widely promoted for control of both quality and quantity of urban floods. However, means to optimize the BMPs in a conjunctive quantity/quality framework are still under research. In this paper, three objective functions were considered: (1) minimization of the total flood damages, cost of BMP implementation and cost of land-use development; (2) reducing the amount of TSS (total suspended solid) and BOD5 (biological oxygen demand), representing the pollution characteristics, to below the threshold level; and (3) minimizing the total runoff volume. The biological oxygen demand and total suspended solid values were employed as two measures of urban runoff quality. The total surface runoff volume produced by sub-basins was representative of the runoff quantity. The construction and maintenance costs of the BMPs were also estimated based on the local price standards. Urban runoff quantity and quality in the case study watershed were simulated with the Storm Water Management Model (SWMM). The NSGA-II (Non-dominated Sorting Genetic Algorithm II) optimization technique was applied to derive the optimal trade off curve between various objectives. In the proposed structure for the NSGA-II algorithm, a continuous structure and intermediate crossover were used because they perform better as far as the optimization efficiency is concerned. Finally, urban runoff management scenarios were presented based on the optimal trade-off curve using the <i>k</i>-means method. Subsequently, a specific runoff control scenario was proposed to the urban managers
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