598 research outputs found

    Nonlinear Channel Estimation Error Effect on Capacity of MIMO System

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    This paper presents the effect of nonlinearity and the effect of estimation error on the channel capacity in MIMO system. We consider a nonlinear MIMO channel, and compare the capacity of Rayleigh MIMO channel model with estimation error with the nonlinear model, at different estimation errors. We consider the estimation error as Gaussian distribution. The simulation results show that the channel capacity of linear and nonlinear MIMO channels are sensitive to the channel estimation error, and due to the nonlinearity, the capacity is less than linear channel. Keywords: MIMO, MIMO Modeling, channel capacity, channel estimation error, nonlinear MIMO channel.

    Porphyrins profile by high performance liquid chromatography/electrospray ionization tandem mass spectrometry for the diagnosis of porphyria

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    Porphyrias are a group of inherited or acquired disorders of certain enzymes in the heme bio-synthetic pathway. Most porphyria symptoms are nonspecific and occur intermittently; resulting frequently in missed diagnosis since the disease itself is a rare one. The aim of the study is toestablish a new reliable and accurate laboratory method for separation, identification and quantitation of urinary porphyrins by liquid chromatography tandem mass spectrometry (LC/MS/MS) and thereby the diagnosis of different porphyria types for the first time in Egypt. Screening by plasma fluorescence and quantitative determination of urinary porphyrins by high performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC/ESI/MS/MS) of 50 clinically suspected patients revealed one case of variegate porphyria and five cases of porphyria cutanea tarda. Plasma fluorescence scanning is a simple procedure that can be used as screening test to detect porphyria patients that require quantitation of urinary porphyrins as a second step. Quantitative determination of urinary porphyrins using HPLC/ESI/MS/MS and ion mapping techniques are applicable for the differential diagnosis of porphyria types, since each type has a characteristic porphyrins excretion profile. Quantitative determination of urinary porphyrins by HPLC/ESI/MS/MS used in this study is a modification for the method Stoev et al. while ion mapping technique is a new technique invented by the research team at the Biochemical Genetics Department

    MINIMIZING POSTHARVEST LOSSES IN POTATO (Solanum tuberosum L.) TUBER USING GAMMA IRRADIATION, MINT OIL AND PACLOBUTRAZOL UNDER UNREFRIGERATED STORAGE CONDITION

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    This experiment was carried out on potato tubers during the two successive seasons of 2013/2014 and 2014/2015 at the Department of Natural Products Research, National Center for Radiation Research and Technology, Nasr City, Cairo, Egypt. The research aims to reduce losses resulting from the storage at room temperature and to reduce cold storage costs of potato tubers using gamma radiation, mint oil and paclobutrazole treatments.     Potato tubers cv. Sponta were treated with 100 Gy of gamma radiation, 5% of mint oil and 100 ppm of paclobutrazole during the two successive seasons of 2013/2014 and 2014/2015. Results showed that, tubers irradiated with 100 Gy and soaked in 100 ppm paclobutrazole scored the lowest percentage of weight loss, sprouting, shrinkage, decay and total lost percentage. As for the effect of soaking tubers in 5% mint oil, results showed a higher percent of shrinkage than other treatments. On the other hand tubers irradiated with 100 Gy of gamma irradiation then soaked in 100 ppm of paclobutrazole had higher contents of starch than other tested treatments

    Calibration and validation of SALTMED model under dry and wet year conditions using chickpea field data from Southern Portugal

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    The SALTMED model is one of the few available generic models that can be used to simulate crop growth with an integrated approach that accounts for water, crop, soil, and field management. It is a physically based model using the well-known water and solute transport, evapotranspiration, and water uptake equations. In this paper, the model simulated chickpea growth under different irrigation regimes and a Mediterranean climate. Five different chickpea varieties were studied under irrigation regimes ranging from rainfed to 100 % crop water requirements, in a dry and a wet year. The calibration of the model using one of the chickpea varieties was sufficient for simulating the other varieties, not requiring a specific calibration for each individual chickpea variety. The results of calibration and validation of the SALTMED model showed that the model can simulate very accurately soil moisture content, grain yield, and total dry biomass of different chickpea varieties, in both wet and dry years. This new version of the SALTMED model (v. 3.02.09) has more features and possibilities than the previous versions, providing academics and professionals with a very good tool to manage water, soil, and crops

    Interleukin 6 (IL6) as a predictor outcome in patients with compensated cirrhosis and symptomatic gall stones after cholecystectomy

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    Compensated cirrhosis means that the liver is heavily scarred but can still perform many important functions; many peoples with compensated cirrhosis have gall bladder stones. The advantages of laparoscopic cholecystectomy (LC) for most patients have been extensively published. However its benefits and successful use in patients with cirrhosis are less documented. The study compromised 50 patients with symptomatic gallstone in compensated liver disease and undergone either open cholecystectomy (OC) or laparoscopic cholecystectomy. These patients were randomized into two groups: Group I included 24 patients who underwent OC, and group II included 26 patients who underwent LC. Patient’s age, sex, clinical presentation and Child-Turcotte-Pugh (CTP) class were documented. No patients in this study had CTP class c cirrhosis. IL-6 was measured by ELISA, postoperative pain (measured by Visual analog scale), hospital stay, blood loss, recovery time (return to work), and liver function tests were documented. IL-6 was significantly lowered at 6th hour and 12th hour post operative in LC group. Mean surgical time was significantly longer in OC than LC group, (mean ±SD, 96.6 ±32 vs 58.7 ± 23.8 min, P = 0.037). No patients in group II required any blood replacement in contrast to 9 patients (37.5%) in group I. Intraoperative bleeding remained significantly higher in group I (P = 0.043). No patients in group II had wound complications compared with 5 patients (29.14%) in group I. Group I had significantly longer hospital stay than group II, mean 9.0+ 1.3 days (median 7) vs 2.3 days + 1.9 (median 2.5); P = 0.001. Our results were demonstrated that laparoscopic cholecystectomy can be performed safely in patients with CTP class A and B cirrhosis. IL-6 was more significantly, increased post operatively in open cholecystectomy than laparoscopic one and it correlated well with intensity of operative trauma. Keywords: Interleukin 6; Liver cirrhosis; Cholecystectom

    An Investigation into Mechanical Properties of Ductile Cast Iron with Different Heat Treatment Processes

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    The mechanical properties as well as microstructure of the ductile cast iron (DCI) are most likely affected by heat treatments. In this work, the mechanical properties of different heat treated of DCI alloy were investigated. Two heat treatment (HT) processes were conducted for DCI; austempering and quenching followed by lower tempering. The melted alloy of DCI was poured in Y-block, from which the specimens of the mechanical tests were prepared. Experimental tests were carried out to investigate the effect of these HT processes on the mechanical properties. A comparison between mechanical properties due to HT and as cast DCI are presented and discussed. The results showed that there is a difference in microstructure, homogeneity, wear rate and compression of DCI based on the conducted heat treatment

    Simplicity versus complexity in modelling groundwater recharge in Chalk catchments

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    Models of varying complexity are available to provide estimates of recharge in headwater Chalk catchments. Some measure of how estimates vary between different models can help guide the choice of model for a particular application. This paper compares recharge estimates derived from four models employing input data at varying spatial resolutions for a Chalk headwater catchment (River Pang, UK) over a four-year period (1992-1995) that includes a range of climatic conditions. One model was validated against river flow data to provide a measure of their relative performance. Each model gave similar total recharge for the crucial winter recharge period when evaporation is low. However, the simple models produced relatively lower estimates of the summer and early autumn recharge due to the way in which processes governing recharge especially evaporation and infiltration are represented. The relative uniformity of land use, soil types and rainfall across headwater, drift-free Chalk catchments suggests that complex, distributed models offer limited benefits for recharge estimates at the catchment scale compared to simple models. Nonetheless, distributed models would be justified for studies where the pattern and amount of recharge need to be known in greater detail and to provide more reliable estimates of recharge during years with low rainfall.</p> <p style='line-height: 20px;'><b>Keywords:</b> Chalk, modelling, groundwater recharge</p

    Wheat Fertilization with Special Reference to Soil Properties and Groundwater Composition in Heavy Clay Soil from Egypt

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    Egypt is considered to be a heavy user of chemical fertilizers, especially NPK fertilizers. Thus, sustainable NPK-fertilizer management should be considered to minimize nutrient losses to the environment via volatilization or leaching. Therefore, the objectives of this study were to investigate the effect of different levels of NPK fertilization on some soil chemical properties, the chemical composition of groundwater and the yield and yield components of wheat plant under different treatments of NPK. Field experiments were carried out to study the effect of NPK application on soil properties and groundwater quality as well as wheat yield. Groundwater and soil samples were collected after the first, the third irrigation as well as after harvesting from each treatment for chemical analysis. The highest value of soil salinity was 1.64 dS m-1 after wheat harvesting compared to it before planting (1.13 dS m-1). Values of pH after wheat harvesting ranged from 7.39 to 8.01 (7.67 before planting). Concentration of soluble cations in the ground water after harvesting was higher than it before planting. Concerning soluble salts, Na+ and Cl- was the dominate ions in the soil solution and cation concentration had the descending order: Na+ > Ca++ > Mg++ > K+ and anions had the following order: Cl- > SO4-- > HCO3-. The mean values of available N after wheat harvesting ranged from 8 to 19 mg N kg-1 (38 – 42 mg N kg-1 before planting). The highest value of available phosphorus after wheat harvesting was 11 mg P kg-1 (19.4 mg P kg-1 before planting). Available K ranged from 97 to 204 mg K kg-1 compared to it before planting (160 – 210 mg K kg-1). The balance fertilization of NPK (N80P22K50) gave the highest yield of wheat, improving soil fertility and decrease nutrient leaching to ground water. The grain yield of wheat was highly significant increased with increasing N levels up to 120 kg N acre-1. The highest mean value of grain yield over the two seasons was 3.5 Mg acre-1
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