4,646 research outputs found

    The 3XMM/SDSS Stripe 82 Galaxy Cluster Survey: Cluster catalogue and discovery of two merging cluster candidates

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    We present a galaxy cluster survey based on XMM-Newton observations that are located in Stripe 82 of the Sloan Digital Sky Survey (SDSS). The survey covers an area of 11.25 deg2^2. The X-ray cluster candidates were selected as serendipitously extended detected sources from the third XMM-Newton serendipitous source catalogue (3XMM-DR5). A cross-correlation of the candidate list that comprises 94 objects with recently published X-ray and optically selected cluster catalogues provided optical confirmations and redshift estimates for about half of the candidate sample. We present a catalogue of X-ray cluster candidates previously known in X-ray and/or optical bands from the matched catalogues or NED. The catalogue consists of 54 systems with redshift measurements in the range of 0.05-1.19 with a median of 0.36. Of these, 45 clusters have spectroscopic confirmations as stated in the matched catalogues. We spectroscopically confirmed another 6 clusters from the available spectroscopic redshifts in the SDSS-DR12. The cluster catalogue includes 17 newly X-ray discovered clusters, while the remainder were detected in previous XMM-Newton and/or ROSAT cluster surveys. Based on the available redshifts and fluxes given in the 3XMM-DR5 catalogue, we estimated the X-ray luminosities and masses for the cluster sample. We also present the list of the remaining X-ray cluster candidates (40 objects) that have no redshift information yet in the literature. Of these candidates, 25 sources are considered as distant cluster candidates beyond a redshift of 0.6. We also searched for galaxy cluster mergers in our cluster sample and found two strong candidates for newly discovered cluster mergers at redshifts of 0.11 and 0.26. The X-ray and optical properties of these systems are presented.Comment: 17 pages, 12 figures, accepted for publication in A&A, revised version after language editin

    Reduced OoB Emission and PAPR Using Partial-OSLM technique in 5G UFMC Systems

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    Universal-filtered multi-carrier (UFMC) waveformis considered as a potential candidate for next generation wirelesssystems due to its robustness against inter-carrier interference(ICI) and the low latency required in 5G systems. In this paper, apulse shaping approaches in UFMC technique is studied to reducethe spectral leakage into nearby sub-bands. The performance ofvarious types of window functions such as Chebychev, Hamming,Hanning and Blackman with UFMC are compared. This leadsto different coefficients and attenuation shapes, that enabledto choose the proper window function. Finally, a new selectivemapping (SLM) peak to average power ratio (PAPR) reductiontechnique is proposed to enhance the UFMC system performance.Results show that the BER performance of UFMC with allwindows functions are the same. However, Blackman windowfunction has a higher attenuation for sidebands compared withothers

    Is Helicobacter Pylori Associated with a Migraine?

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    Objective: To determine whether Helicobacter pylori (H. pylori) is associated with migraine headache. Design: Case-control study. Settings: Local tertiary Hospitals in Cairo, Egypt and in HaferAlbaten, Saudi Arabia. Participants: A total of 70 patients with migraine who were 7 to 17 years old and who fulfilled the International Headache Society criteria for migraine and a total of 50 controls without migraine who were matched by the country of origin, age, sex, ethnicity, and socioeconomic status to the 70 migraine cases. Main Outcome Measures: Antibody levels to H. pylori (IgG) and H. pylori stool antigens were compared between the two groups. Results: Significant association was found between H. pylori and migraine and of the total of 70 migraineur cases, 55.7% were positive for H. pylori stool antigen testing compared to 20% in control group (P value=0.0002). Joint pain was reported in 44.3% and 18.0% of cases and controls respectively (P value=0.0034). Conclusion: H. pylori is associated with migraine without aura and may be a causative factor. Moreover, H. pylori may induce joint pain in the migraineur patients

    Determine the Optimal Sequence-Dependent Completion Times for Multiple Demand with Multi-Products Using Genetic Algorithm

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    Sequencing is the most impact factor on the total completion time , the products sequences inside demands that consist from muti-product and for multiple demands . It is very important in assembly line and batch production . The most important drawback of existing methods used to solve the sequencing problems is the sequence must has a few products and dependent completion time for single demand . In this paper we used genetic algorithm –based Travelling Salesman Problem with Precedence Constraints Approach ( TSPPCA)  to minimize completion time . The main advantage of this new method , it is used to solve the sequencing problems for multiple demand with multi-product In this paper , we compare between modify the assignment method ( MAM ) and genetic algorithm  depend on least completion time , the results discern that   GA  has minimum completion time Keywords: products sequences , completion time , travel salesman problem (TSP ) , TSPPCA , genetic algorithm. 

    Determine The Optimal Sequence - dependent Setup Cost and / or Setup Time for Single Demand with Multiple Products Using Modified Assignment Method

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    Sequencing is the most impact factor on the total setup cost and / or time and the products sequences inside demands that consist from muti-products . It is very important in assembly line and batch production . The most important drawback of existing methods used to solve the sequencing problems is the sequence must has a few products and dependent setup cost or setup time . In this paper we modify the assignment method –based goal programming method to minimize the setup cost and / or setup time. The main advantage of this new method , it is not affected by the number of products in the sequence and can treatment the sequence problems with two or more objectives . Keywords: products sequences , setup cost , setup time , travel salesman problem (TSP ) , modified assignment method , goal programming

    Frequency of Glomerular Dysfunction in Children with Beta Thalassaemia Major

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    Objectives: This study investigated the frequency of glomerular dysfunction in children with beta thalassaemia major (β-TM) by using different markers and correlating them with serum ferritin and iron chelation therapy. Methods: The study, carried out between August 2011 and May 2012, included 100 patients with β-TM, in two groups. Group Ia (n = 62) received chelation therapy (deferoxamine). Group Ib (n = 38) received followup care at the Pediatric Hematology Outpatient Clinic, Minia University Children’s Hospital, Egypt. Group II included 50 apparently healthy controls, age- and sex-matched to Group I. All patients underwent a thorough history-taking, clinical examination and laboratory investigations. Results: Compared to Group II, Groups Ia and Ib had significantly higher levels of cystatin C, serum creatinine and serum ferritin, and a higher albumin/ creatinine ratio in their urine, and a significantly lower estimated glomerular filtration rate (eGFR) and creatinine clearance (P <0.05). Moreover, Group Ιa had a significantly lower eGFR and creatinine clearance than Group Ib. Cystatin C had a highly significant strong negative correlation with eGFR and creatinine clearance and a significantly strong positive correlation with serum ferritin, and a higher sensitivity and specificity than serum creatinine and creatinine clearance for small changes in GFR. Conclusion: β-TM patients had a high frequency of glomerular dysfunction—possibly attributable to chronic anaemia, iron overload or chelation therapy. Periodic renal assessment is mandatory to detect renal complications. Cystatin C is a promising marker to monitor glomerular dysfunction, having a higher sensitivity and specificity than serum creatinine and creatinine clearance for small changes in GFR

    Optimizing Lead-free MASnBr3 Perovskite Solar Cells for High-Efficiency and Long-Term Stability Using Graphene and Advanced Interface Layers

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    Perovskite solar cells (PSCs) have garnered significant attention in the scientific community due to their rapid increase in performance. Inorganic perovskite devices have been noted for their high performance and long-term stability. This study introduces a device optimization process guided by modeling to produce high-efficiency PSCs using lead-free n-i-p methylammonium tin bromide (MASnBr3) materials. We have thoroughly examined the impact of both the absorber and interface layers on the optimized structure. Our approach utilized graphene as the interface layer between the hole transport and absorber layers. We employed zinc oxide (ZnO)/Al and 3C-SiC as interface layers between the absorber and electron transport layers. The optimization process involved adjusting the thicknesses of the absorber layer and interface layers and minimizing defect densities. Our proposed optimized device structure, ZnO/3C-SiC/MASnBr3/graphene/CuO/Au, demonstrates theoretical power conversion efficiencies of 31.97%, fill factors of 89.38%, a current density of 32.54 mA/cm2, a voltage of 1.112 V, and a quantum efficiency of 94%. This research underscores the ability of MASnBr3 as a nontoxic perovskite material for sustainable energy from renewable sources' applications

    Molecular study of Helicobacter pylori virulence genes CagA, Hpa and BabA2 in Egyptian patients

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    Objective: The objective of this study was to detect virulence genes of Helicobacter pylori (H.pylori) cagA, babA2 and hpa in gastric biopsies from patients with different stages of gastritis by polymerase chain reaction to correlate the presence of genes with the severity of the diseases.Method: A total of 80 non repetitive gastric biopsies from antrum of the stomach were obtained from the patients and subjected to study for histological examination, unease activity, culture for H.pylori, and polymerase chain reaction studies of virulence genes cagA, babA2 and hpa.Results: The most frequent detected gene by PCR was hpa (66.7%) and followed by cagA and babA2 (61.6%) for each. There was significant association between the three genes (P=0.0001). The study of the association between the virulence gene of H.pylori and different clinical symptoms revealed significant association of dyspepsia with cagA(P=0.001) babA2 and hpa (P=0.0001), regurgitation with cagA and babA2( P=0.002),vomiting with cagA and babA2 (P=0.01, P=0.002, respectively) and nausea with cagA and babA2 (P=0.0001, P=0.03, respectively). The virulence genes were detected in gastric ulcer. The degree of inflammation in histopathological examination was also statistically significant associated with the presence of virulences genes cagA (P=0.01), babA2 (p=0.0001) and hpa (P=0.0001)The present study highlights the presence of virulence genes in H.pylori associated with gastric ulcer. The genes cagA, babA2 and hpa are prevalent among the strains affecting the patients. Moreover, these genes are associated with marked clinical and pathological severity. The genes are significantly associated with each other. Further studies are recommended to validate these findings.Keywords: Gastritis, Genotypes, H.pylori, cagA, babA2, hpa, PC

    Mitigation of Lightning Hazards at the More Sensitive Points in Wind Farms Using Ant-Colony Optimization Technique

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    The lightning energy can be very harmfull to the wind turbine farm components. This paper attempts to evaluate the overvoltages at the sensitive points in wind farm, using ATP-EMTP package program. Four cases were performed; a) the transient voltage distribution in the insulating layer of the control line, b) the transient voltage on the control equipment, c) the coupling voltage between the tower and the control, and, d) the transient voltage distribution in the wind turbine WT generator, boast transformers and grid. These cases were performed under different lightning current conditions and at conventional design and proper design of grounding system. The results show that the ground potential rise (GPR) is reduced with using the proper design of wind turbine ground system, but the induced voltage at the control system will not affected. This work determines the optimum location of wind turbine at the areas of maximum lightning incidence. Ant colony optimization (ACO) technique is implemented to find the optimum wind farm location. This work enhances the protection strategy of the wind farms against lightning stroke
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