Simulation of Logging While Drilling Tools Based on Amorphous Si:H and LaBr3:Ce Detectors

Bore hole logging data represent the properties of rocks, such as porosity, density and constitutiveelements of formation, as a function of depth in a well. Properties of rocks are obtained from thermal neutron counting and gamma ray radiation due to neutron activation. Transport of neutrons, from an Am-Be source situated in a bore-hole tool, through rock media to detectors, has been simulated using a GEANT4 radiation transport code. The high precision GEANT4 cross section library was used to gain better analyses about well formation. In this paper we present the results of simulation of logging tools based on boron coated amorphous silicon detector for thermal neutron detection and LaBr3:Ce detector for gamma spectroscopy. Key words: Well logging; Spectroscopy; GEANT

BREATH-HOLDING SPELLS: AN ANALYSIS OF 43 CASES

Objective:Breath holding spells, very often misinterpreted as epileptic seizures, are most common in children aged 6 months to 6 years of age. In this investigation, we sought to prospectively document the natural history of breath holding spells (BHS) among children with cyanotic, pallid and mixed type BHS referred for neurological consultation.Materials & Methods:This was a cross-sectional study in which a total of 43 children (23 boys, 20 girls) with BHS, admitted to the out patient clinic of the Children's Hospital Medical Center, between Sept 1998 and June 1999, were enrolled. A structured interview was under taken at the time of initial consultation to confirm BHS and its type, associated phenomenon, family history, sex and age at initiation of spells. Laboratory, electroencephalographic and electrocardiographic tests were done.Results:Patients were between 1.7 and 42.8 months (mean age 18.4 months). In 76.8% of cases, BHS began during the first 12 months of age. Anger and pain were the most common triggering factors (65.1 %). A positive family history of BHS was identified in 51% and parental consanguinity was found in 30% of cases. The spells were cyanotic in 79.1% (34 children). 78% of cases were iron deficient and 53% of cases had iron deficiency anemia.Conclusion:The results of this study emphasize the role of genetic factors in BHS; measurement of hemoglobin and serum ferritin is recommended all such cases.Key words: Breath-holding spells, Iron deficiency, Anemia, Serum ferriti

Amino Acid Features of P1B-ATPase Heavy Metal Transporters Enabling Small Numbers of Organisms to Cope with Heavy Metal Pollution

Phytoremediation refers to the use of plants for extraction and detoxification of pollutants, providing a new and powerful weapon against a polluted environment. In some plants, such as Thlaspi spp, heavy metal ATPases are involved in overall metal ion homeostasis and hyperaccumulation. P1B-ATPases pump a wide range of cations, especially heavy metals, across membranes against their electrochemical gradients. Determination of the protein characteristics of P1B-ATPases in hyperaccumulator plants provides a new opportuntity for engineering of phytoremediating plants. In this study, using diverse weighting and modeling approaches, 2644 protein characteristics of primary, secondary, and tertiary structures of P1B-ATPases in hyperaccumulator and nonhyperaccumulator plants were extracted and compared to identify differences between proteins in hyperaccumulator and nonhyperaccumulator pumps. Although the protein characteristics were variable in their weighting, tree and rule induction models; glycine count, frequency of glutamine-valine, and valine-phenylalanine count were the most important attributes highlighted by 10, five, and four models, respectively. In addition, a precise model was built to discriminate P1B-ATPases in different organisms based on their structural protein features. Moreover, reliable models for prediction of the hyperaccumulating activity of unknown P1B-ATPase pumps were developed. Uncovering important structural features of hyperaccumulator pumps in this study has provided the knowledge required for future modification and engineering of these pumps by techniques such as site-directed mutagenesis

Graph Hybrid Summarization

One solution to process and analysis of massive graphs is summarization. Generating a high quality summary is the main challenge of graph summarization. In the aims of generating a summary with a better quality for a given attributed graph, both structural and attribute similarities must be considered. There are two measures named density and entropy to evaluate the quality of structural and attribute-based summaries respectively. For an attributed graph, a high quality summary is one that covers both graph structure and its attributes with the user-specified degrees of importance. Recently two methods has been proposed for summarizing a graph based on both graph structure and attribute similarities. In this paper, a new method for hybrid summarization of a given attributed graph has proposed and the quality of the summary generated by this method has compared with the recently proposed method for this purpose. Experimental results showed that our proposed method generates a summary with a better quality

Temperature-dependent photoluminescence of ZnO layers grown on 6H-SiC substrates

Temperature-dependent photoluminescence(PL) of ZnO layers grown on 6H-SiC substrates has been described. The PLspectra were dominated by free exciton (FX) emission throughout the whole temperature range, which reflects shallow nonradiative centers in high crystalline ZnO layers. The temperature-dependent exciton peak energy as well as intensity quenching due to overlapping of FX and D⁰X (donor-bound exciton) bands has been addressed with an inclusion of donor-bound exciton-like defects. The D⁰Xlinewidth of ∼8 meV exhibited the thermal activation energy of ∼16 meV, closely consistent with the exciton-defect binding energy. This particular bound-exciton peak suggests that it dissociates into a FX and a neutral-donor-bound-like defects pair complex with the increase of temperature.This work was supported in part by the Special Postdoctoral Research Fellowship Program, Photodynamics Research Center, The Institute of Physical and Chemical Research, Japan

Development of Sensitive Detection of Cryptosporidium and Giardia from Surface Water in Iran

Background: The protozoan parasites Cryptosporidium spp. and Giardia are known to occur widely in both raw and drinking waters. They are two of the causative agents of waterborne out-breaks of gastroenteritis throughout the world. In the present study, a PCR assay and FA were developed for detection of Cryptosporidium oocysts and Giardia cyst in environmental samples. Methods: We have detected Cryptosporidium spp. oocysts and Giardia cysts in seeded and un-seeded environmental water samples by PCR method. Water samples were spiked with oocysts (50, 100,300,500) and filtrated with a 1.2-µm pore size cellulose nitrate and follow by DNA extrac¬tion and purification by QIAamp DNA mini kit. Nested-PCR assay amplified an 850 bp fragment of 18s rRNA gene specific for Cryptosporidium and 435 bp fragment of glutamate dehydrogenase (GDH) target gene for Giardia. Also many river water from north of Iran, be checked by these methods. Results: Cryptosporidium and Giardia DNAs were detected in seeded water sample and Giardia was detected in all 5 water samples from river in north of Iran by nested- PCR and FA. Also in one river water sample, Cryptosporidium was detected.Conclusion: This protocol is effective for detection of these waterborne parasites in treated and untreated water samples. This study can also serve as a platform for further investigations and research water source in Iran