3,342 research outputs found

    Introductory Chapter: Safety Aspects in Nuclear Engineering

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    IR optical fiber-based noncontact pyrometer for drop tube instrumentation

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    The design of a two color pyrometer with infrared optical fiber bundles for collection of the infrared radiation is described. The pyrometer design is engineered to facilitate its use for measurement of the temperature of small, falling samples in a microgravity materials processing experiment using a 100 meter long drop tube. Because the samples are small and move rapidly through the field of view of the pyrometer, the optical power budget of the detection system is severly limited. Strategies for overcoming this limitation are discussed

    PROPORTIONAL EFFECT OF OUTLIERS ON OVER-DISPERSION

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    The impact of outlier on analysis of time series data in causing over-dispersion was examined. The problemof overdispersion is central to all General Linear Models (GLM's) having discrete responses. If the estimated dispersion after fitting is not near the expected values, then the data may be over dispersed. One of the causes of overdispersion is outlier. Outlier is a data which is unusual with respect to the group of data in which it is found. In this paper, data were simulated based on poison model using SPSS and first analysed to see whether the estimated parameters is unbiased of the fixed parameters. Thereafter, two different values of outliers, 10's and 20's were introduced to different percentages of the generated data and then analysed using the STATA package to observe the effect of the outliers being introduced on the data for small, moderate and large samples. The data simulated were replicated 300 times for all categories. The averages of the results were computed. The results showed that the higher the percentage of outliers the more the over-dispersion occurs in the models and the larger the sample sizethe less the over-dispersion

    Radiation Measurements in Soil of Nusirate in the middle of Gaza-Strip Using Nuclear Track Detector CR-39 and Electra Plus

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    Because of the hazards of radon activity and its daughter products to human health, several studies were conducted to measure radiation in environment including soil and building materials. Alpha particles radiation contents of soil samples were measured using solid state nuclear track detector (SSNTD) CR-39. Soil samples were collected from the middle region of Gaza-Strip, in Nusirate area. Alpha activity per unit volume were evaluated in the sample using solid state nuclear track detector. Results showed that the activity of Alpha particles in soil has a maximum value 9.305 Bq/m3, and minimum 2.878 Bq/m3, and average is 5.244 Bq/m3. Also results using Electra Plus were discussed and compared with other published data

    Hepcidin and iron status in chronic kidney disease

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    Hepcidin is a critical inhibitor of iron export frommacrophages, enterocytes, and hepatocytes. Given that itis filtered and degraded by the kidney, its elevated levelsin renal failure have been suggested to play a role in thedisordered iron metabolism of uremia. It is a smalldefensin-like peptide whose production by hepatocytes ismodulated in response to anemia, hypoxia, orinflammation. Hepcidin could also act as an indicator offunctional iron deficiency (FID) in chronic kidneydisease (CKD) patients. This study was performed toassess hepcidin and its correlations with renal function,iron status parameters {serum iron, serum ferritin,transferrin saturation (TSAT) and soluble transferrinreceptor (sTfR)}, inflammatory cytokines (IL-6&IFN-?)and inflammatory markers (CRP) in patients with CKDeither on conservative treatment or on maintenancehemodialysis (HD). Serum prohepcidin was higher inHD patients compared to controls and CKD patients. Inthe whole patient group, serum hepcidin correlatedsignificantly with hemoglobin (Hb), IL-6, creatinine,CRP, sTfR and urinary hepcidin. In HD groupprohepcidin correlated significantly with creatinine.Multiple regression analysis showed that prohepcidinwas most predicted by serum creatinine and CRP.Elevated prohepcidin levels in HD patients studied couldmainly be due to its accumulation in impaired renalfunction in addition to low-grade inflammation,frequently encountered in this population

    Persistent X-Ray Photoconductivity and Percolation of Metallic Clusters in Charge-Ordered Manganites

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    Charge-ordered manganites of composition Pr1−x(Ca1−ySry)xMnO3\rm Pr_{1-x}(Ca_{1-y}Sr_{y})_{x}MnO_3 exhibit persistent photoconductivity upon exposure to x-rays. This is not always accompanied by a significant increase in the {\it number} of conduction electrons as predicted by conventional models of persistent photoconductivity. An analysis of the x-ray diffraction patterns and current-voltage characteristics shows that x-ray illumination results in a microscopically phase separated state in which charge-ordered insulating regions provide barriers against charge transport between metallic clusters. The dominant effect of x-ray illumination is to enhance the electron {\it mobility} by lowering or removing these barriers. A mechanism based on magnetic degrees of freedom is proposed.Comment: 8 pages, 4 figure

    Augmented reality flavor: cross-modal mapping across gustation, olfaction, and vision

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    Gustatory display research is still in its infancy despite being one of the essential everyday senses that human practice while eating and drinking. Indeed, the most important and frequent tasks that our brain deals with every day are foraging and feeding. The recent studies by psychologists and cognitive neuroscientist revealed how complex multisensory rely on the integration of cues from all the human senses in any flavor experiences. The perception of flavor is multisensory and involves combinations of gustatory and olfactory stimuli. The cross-modal mapping between these modalities needs to be more explored in the virtual environment and simulation, especially in liquid food. In this paper, we present a customized wearable Augmented Reality (AR) system and olfaction display to study the effect of vision and olfaction on the gustatory sense. A user experiment and extensive analysis conducted to study the influence of each stimulus on the overall flavor, including other factors like age, previous experience in Virtual Reality (VR)/AR, and beverage consumption. The result showed that smell contributes strongly to the flavor with less contribution to the vision. However, the combination of these stimuli can deliver richer experience and a higher belief rate. Beverage consumption had a significant effect on the flavor belief rate. Experience is correlated with stimulus and age is correlated with belief rate, and both indirectly affected the belief rate. 2021, The Author(s).This work was partly supported by NPRP Grant #NPRP 11S-1219-170106 from the Qatar National Research Fund (a member of Qatar Foundation). This work also was not possible without the effort of students Babkir Elnimah, Ali Hazi, and Ahmed Ibrahim as part of their senior project.Scopu

    Understanding the dynamics of photoionization-induced solitons in gas-filled hollow-core photonic crystal fibers

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    We present in detail our developed model [Saleh et al., Phys. Rev. Lett. 107] that governs pulse propagation in hollow-core photonic crystal fibers filled by an ionizing gas. By using perturbative methods, we find that the photoionization process induces the opposite phenomenon of the well-known Raman self-frequency red-shift of solitons in solid-core glass fibers, as was recently experimentally demonstrated [Hoelzer et al., Phys. Rev. Lett. 107]. This process is only limited by ionization losses, and leads to a constant acceleration of solitons in the time domain with a continuous blue-shift in the frequency domain. By applying the Gagnon-B\'{e}langer gauge transformation, multi-peak `inverted gravity-like' solitary waves are predicted. We also demonstrate that the pulse dynamics shows the ejection of solitons during propagation in such fibers, analogous to what happens in conventional solid-core fibers. Moreover, unconventional long-range non-local interactions between temporally distant solitons, unique of gas plasma systems, are predicted and studied. Finally, the effects of higher-order dispersion coefficients and the shock operator on the pulse dynamics are investigated, showing that the resonant radiation in the UV [Joly et al., Phys. Rev. Lett. 106] can be improved via plasma formation.Comment: 9 pages, 10 figure
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