331 research outputs found
Surface salinity determination for the Bosphorous with nuclear technique, a new analytical model and evaluation
İstanbul Boğazı, Türk Boğazlar Sistemini oluşturan Marmara Denizi ve Çanakkale Boğazı’ndan daha özel bir önem taşımaktadır. Karadeniz’den gelen nispeten az tuzlu su üst akış olarak ve Marmara Denizi’nden gelen daha tuzlu su alt akış olarak İstanbul Boğazı boyunca iki katmanlı akışı oluşturmaktadır. Yoğunluk farkından dolayı iki katmanlı akış halinde boğaz boyunca akan tuzlu suda farklı akış rejimlerinden dolayı karışımlar meydana gelmektedir. Önemli bir dar su yolu olan İstanbul Boğazı’nın yüzey tuzluluk değerleri farklı lokasyon ve mevsimlerde nötron aktivasyon analiziyle tayin edilmiştir. Günümüzde çok çeşitli tuzluluk tayin yöntemleri kullanılmakla beraber literatürde, nötron aktivasyon analiziyle tuzluluk tayinine ilişkin bir yayına rastlanmamıştır. Nötron aktivasyon analizi element analizinde sıkça kullanılan bir nükleer teknik durumundadır. Tuzluluk tayini için kullanılan nötron akivasyon analizi yönteminde sodyum konsantrasyonu elde edilerek tuzluluk değerlerine gidilmiştir. Nötron aktivasyon analizi tuzluluk sonuçlarını kıyaslamak için konvansiyonel bir tuzluluk tayin tekniği olan uçurma yöntemi seçilmiştir. Nötron aktivasyon analizi tuzluluk sonuçlarının uçurma sonuçlarına yakınsadığı gösterilmiştir. Nötron aktivasyon analizi tuzluluk değerleri kullanılarak yere ve zamana bağlı matematik bir model geliştirilmiştir. Bu yeni model İstanbul Boğazı’na özgü parametreleri barındırmaktadır. Deneysel ve matematik model sonuçları FEMLAB 3.1 programında tek boyutlu difüzyon denkleminin çözülmesiyle oluşan simülasyon sonuçlarıyla kıyaslanmıştır. Deneysel ve teorik sonuçların iyi bir uyum içinde olduğu ortaya çıkmıştır. Böylelikle nötron aktivasyon analizi ile deniz suyu tuzluluk tayininin yapılabileceği ve önerilen analitik modelin güvenilirlikle kullanılabileceği gösterilmiştir.Anahtar Kelimeler: İstanbul Boğazı, tuzluluk, Na-24, uçurma yöntem, nötron aktivasyon analizi. Turkish Strait System consists of the Bosphorous, Marmara Sea and Dardanelles. The Bosphorous is the most interesting one because of its strategic role. The Bosphorous is a very important channel in which there are two flows with different salinities. The seawater of Black Sea passes by as the top layer flow and the seawater of Marmara Sea as the bottom layer because of the density difference. For years, the oceanographers work on the Bosphorous two- layer flow. This two-layer flow mixes along the Bosphorous causing salinity dispersion. To have an idea about the surface salinity dispersion, the salinity levels should be determined along the channel. The main aim of the experimental work is to measure the surface salinity level with neutron activation analysis. There are many studies to determine the salinity with different methods which are primarily based on physical and chemical principles. Physical salinity determination methods depend on refractive index, density and electrical conductivity measurements. On the other hand chemical methods are based on chlorinity determination. Beyond the physical and chemical methods there are alternative salinity measuring systems as well. These can be called as "alternative methods". In this study for the salinity determination, neutron activation analysis has been chosen as the experimental method but in the literature there is no study that deals with salinity determination by neutron activation analysis. Neutron activation analysis is a nuclear technique that has widely been used for the element analysis. In neutron activation analysis the sample is irradiated and the isotopes of the mother elemental is formed. The activated samples are usually gamma-active and detecting the gamma rays, the concentration and the element identification can be performed Neutron activation analysis can be named as the "new alternative method for salinity measurement". Initially, surface salinity of the Bosphorous was determined by the neutron activation analysis. On the other hand. evaporation technique which is a routine salinity determination method has been chosen. From the specified sample locations along the Bosphorous, the seawater samples have been collected and stored in polymer bottles. In order to determine the salinity of the samples, small amounts of samples were prepared. First of all, the water of the small samples about 100 cc. were evaporated and from the salt remaining after the water evaporation, again small samples have been prepared for the irradiation. The Bosphorous samples were irradiated with a reference salt sample. The salinity of the Bosphorous samples were determined with an equation which allows a comparison of the reference results with those of the irradiated samples. The results of neutron activation analysis have been compared with those of evaporation and literature. Neutron activation analysis results were in good accuracy with those of evaporation and the literature. With the neutron activation analysis results, a model which depends on position and time has been offered. The offered model was a product of two independent functions. The function depending on the position is an exponential and the time dependent one is a sinusoid. The parameters of the independent functions have been determined by neutron activation salinity results. They have been compared with those of evaporation. The model results were in good agreement with the evaporation ones. A theoretical comparison has also been chosen to be done with the results of neutron activation analysis which have been compared in many ways. For this comparison, a widely used computer programme. FEMLAB 3.1 (Finite Element Method Laboratory). has been selected. This programme has widely been used in many different studies where finite element method is valid. The suitable geometry for the Bosphorous has been formed and one dimensional diffusion equation has also been solved with the parameters of the Bosphorous. The values obtained from one dimensional diffusion equation that has been solved for the Bosphorous have been used in comparison with those of neutron activation analysis, evaporation and the mathematical model and it has been concluded that neutron activation results have been in good accuracy with those of the programme. It is also concluded that neutron activation analysis can be used to determine the salinity and mathematical model as well in relevance. A different study has been done in terms of the experimental work and the analytical model. Keywords: Bosphorous, salinity, Na-24, evaporation method, neutron activation analysis
Universality of the Ising and the S=1 model on Archimedean lattices: A Monte Carlo determination
The Ising model S=1/2 and the S=1 model are studied by efficient Monte Carlo
schemes on the (3,4,6,4) and the (3,3,3,3,6) Archimedean lattices. The
algorithms used, a hybrid Metropolis-Wolff algorithm and a parallel tempering
protocol, are briefly described and compared with the simple Metropolis
algorithm. Accurate Monte Carlo data are produced at the exact critical
temperatures of the Ising model for these lattices. Their finite-size analysis
provide, with high accuracy, all critical exponents which, as expected, are the
same with the well known 2d Ising model exact values. A detailed finite-size
scaling analysis of our Monte Carlo data for the S=1 model on the same lattices
provides very clear evidence that this model obeys, also very well, the 2d
Ising model critical exponents. As a result, we find that recent Monte Carlo
simulations and attempts to define effective dimensionality for the S=1 model
on these lattices are misleading. Accurate estimates are obtained for the
critical amplitudes of the logarithmic expansions of the specific heat for both
models on the two Archimedean lattices.Comment: 9 pages, 11 figure
54/07/28 Why Don\u27t Police Quiz Top Suspect: An Editorial
This editorial, published two days after the conclusion of the Coroner\u27s Inquest, describes Sam as a proven liar who is being shielded by his family and demands that he be taken to police headquarters for further questioning. It declares that if average people\u27 were involved in this murder it would have been cleaned up long ago.https://engagedscholarship.csuohio.edu/sheppard_maxwell_articles/1004/thumbnail.jp
Rapid in situ imaging and whole genome sequencing of biofilm in neonatal feeding tubes: a clinical proof of concept
The bacterial flora of nasogastric feeding tubes and faecal samples were analysed for a low-birth weight (725g) neonate EGA 25 weeks in intensive care. Samples were collected at age 6 and 8 weeks of life. Optical coherence tomography (OCT) was used to visualise bacterial biofilms inside the nasogastric feeding tubes. The biofilm was heterogeneously distributed along the tube lumen wall, and had a depth of up to 500µm. The bacterial biofilm and faecal samples included Enterococcus faecalis and Enterobacter hormaechei. Representative strains, recovered from both feeding tubes and faecal samples, were whole genome sequenced using Illumina, Mi-Seq, which revealed indistinguishable strains, each with less than 28 SNP differences, of E. faecalis and E. hormaechei. The E. faecalis strains were from two sequence types (ST191 and ST211) and encoded for a number of traits related to biofilm formation (BopD), adherence (Epb pili), virulence (cps loci, gelatinase, SprE) and antibiotic resistances (IsaA, tetM). The E. hormaechei were all ST106, and encoded for blaACT-15 β–lactamase and fosfomycin resistance (fosA). This proof of concept study demonstrates that bacterial flora within the neonatal feeding tubes may influence the bacterial colonisation of the intestinal tract and can be visualised nondestructively using OCT
Suppression of the c-erbB-2 gene product decreases transformation abilities but not the proliferation and secretion of proteases of SK-OV-3 ovarian cancer cells
The overexpression of the c-erbB-2 oncogene product has been reported in approximately 20–30% of human ovarian cancers and has been correlated with a poor prognosis in ovarian cancer patients. To investigate the function of p185c-erbB-2 in human ovarian cancer cells, a c-erbB-2-specific single-chain antibody (scFv-5R) was expressed in the c-erbB-2-overexpressing SK-OV-3 cell line using a retroviral expression vector. Eight individual clones expressing the single-chain antibody were isolated. These clones have a prominent retention of the cell surface p185c-erbB-2. In this study we compared the proliferation rate, the anchorage-independent growth, the secretion of matrix metalloproteases and of the urokinase-type plasminogen activator. The clones expressing the c-erbB-2 single-chain antibody, the control cells harbouring the empty vector and the parental SK-OV-3 cells they all had similar proliferation rates in the presence of 10% serum and secreted similar amounts of matrix metalloproteases and of the urokinase-type plasminogen activator. However, the expression of the c-erbB-2 oncogene product offers a strong growth advantage under serum-reduced conditions with 1% serum. In contrast to the parental SK-OV-3 and empty vector control cells, the scFv-5R-expressing clones were not able to grow anchorage-independently. These findings suggest that c-erbB-2 enhances transformation abilities of SK-OV-3 ovarian cancer cells without affecting the secretion of proteases and the proliferation of SK-OV-3 ovarian cancer cells in the presence of high concentrations of serum. © 1999 Cancer Research Campaig
A systematic review of intravenous gamma globulin for therapy of acute myocarditis
BACKGROUND: Intravenous gamma globulin (IVGG) is commonly used in the management of acute myocarditis. The objective of this study was to systematically review the literature evaluating this practice. METHODS: We conducted a comprehensive search (electronic databases, trials registries, conference proceedings, reference lists, contact with authors) to identify studies evaluating the use of IVGG in adults and children with a clinical or histologically proven diagnosis of myocarditis of possible viral etiology and symptoms of less than six months duration. Two reviewers independently screened the searches, applied inclusion criteria, and graded the evidence. RESULTS: Results were described qualitatively; data were not pooled because only one randomized controlled trial (RCT) with 62 patients was identified. The RCT showed no benefit with respect to cardiac function, functional outcome, or event-free survival. A small, uncontrolled trial (n = 10) showed significant improvement in LVEF from a mean of 24% to 41% 12 months after IVGG in nine survivors. A retrospective cohort study of pediatric patients showed improvement in cardiac function and a trend towards improved survival in patients receiving IVGG (n = 21) versus historic controls (n = 25). Ten case reports and two case series (total n = 21) described improvement in cardiac function after administration of IVGG; two case reports showed no benefit of IVGG. One case of hemolytic anemia was attributed to IVGG. CONCLUSION: There is insufficient data from methodologically strong studies to recommend routine use of IVGG for acute myocarditis. Future randomized studies that take into account the etiology of acute myocarditis will be required to determine the efficacy of IVGG
Analysis of the common genetic component of large-vessel vasculitides through a meta- Immunochip strategy
Giant cell arteritis (GCA) and Takayasu's arteritis (TAK) are major forms of large-vessel vasculitis (LVV) that share clinical features. To evaluate their genetic similarities, we analysed Immunochip genotyping data from 1,434 LVV patients and 3,814 unaffected controls. Genetic pleiotropy was also estimated. The HLA region harboured the main disease-specific associations. GCA was mostly associated with class II genes (HLA-DRB1/HLA-DQA1) whereas TAK was mostly associated with class I genes (HLA-B/MICA). Both the statistical significance and effect size of the HLA signals were considerably reduced in the cross-disease meta-analysis in comparison with the analysis of GCA and TAK separately. Consequently, no significant genetic correlation between these two diseases was observed when HLA variants were tested. Outside the HLA region, only one polymorphism located nearby the IL12B gene surpassed the study-wide significance threshold in the meta-analysis of the discovery datasets (rs755374, P?=?7.54E-07; ORGCA?=?1.19, ORTAK?=?1.50). This marker was confirmed as novel GCA risk factor using four additional cohorts (PGCA?=?5.52E-04, ORGCA?=?1.16). Taken together, our results provide evidence of strong genetic differences between GCA and TAK in the HLA. Outside this region, common susceptibility factors were suggested, especially within the IL12B locus
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