1,094 research outputs found
Diagnosis and Surgical Treatment of Hepatic Hydatid Disease
In this report two hundred and twenty six patients with hydatid disease were admitted to the Surgical
Department of Erciyes University (Kayseri) and Şişli Etfal Hospital (Istanbul) between 1978 and 1990
and reviewed retrospectively. One hundred and two patients (45.1%) were male and 124 (54.9%)
female. In the patients with hydatid cysts the most frequent symptom was right upper abdominal pain
(66%). The most frequent signs were hepatomegaly (43.8%) and palpable mass (39%). One hundred
and sixty seven patients (73.9%) were examined with ultrasonography which has a diagnostic value of
94%. Preoperative complications were infection of cyst (7%), intrabiliary rupture (3.5%) and anaphylactic
shock (0.4%). All patients were operated on by using various surgical techniques; omentoplasty
(101), external drainage of residual cavity (64), marsupialization (25), capitonnage (15), introflexion
(10), pericystectomy (6), and hepatic resection (5)
Preparation of high surface area activated carbon from waste-biomass of sunflower piths: Kinetics and equilibrium studies on the dye removal
Sunflower pith (SP), a vast agricultural waste is herein used as a precursor material for highly porous low density activated carbon production. Porosity and flake-like microstructure of the SP in its natural form are shown by micro-computed tomography (Micro-CT). Carbonization process turns the SP into thin, separated carbon flakes of 200 nm thickness. Two types of alkaline based chemical activation with KOH and NaOH are performed to yield SP based activated carbon (AC), K-SPAC and N-SPAC, respectively. Microstructural changes upon carbonization and activation process are elaborated by RAMAN, FTIR and SEM analyses. BET Surface area of the NaOH-activated N-SPAC was calculated as 2690 m2/g and was higher than KOH-activated K-SPAC with 2090 m2/g. Maximum adsorption capacity of N-SPAC was calculated as 965 mg/g whereas it was 580 mg/g for K-SPAC. Adsorption kinetic studies for N-SPAC revealed that at a low initial concentration of dye (500 mg/L), the pseudo first-order kinetic model was predictive. On the other hand, at high initial MB concentration (1000 mg/L), the results indicate that the adsorption kinetics follow the Elovich model with intraparticle diffusion as one of the rate-determining steps. In conclusion, overall results suggest that thanks to its highly porous microstructure, the SP is an alternative renewable AC precursor choice for dye removal applications
Vacuum fluctuations for spherical gravitational impulsive waves
We propose a method for calculating vacuum fluctuations on the background of
a spherical impulsive gravitational wave which results in a finite expression
for the vacuum expectation value of the stress-energy tensor. The method is
based on first including a cosmological constant as an auxiliary constant. We
show that the result for the vacuum expectation value of the stress-energy
tensor in second-order perturbation theory is finite if both the cosmological
constant and the infrared parameter tend to zero at the same rate.Comment: Class. Quantum Grav. 13(1996) 2683-269
Relationship between 1,25‑dihydroxy Vitamin D levels and homeostatic model assessment insulin resistance values in obese subjects
Aim: In this study, our aim is to evaluate the insulin resistance and quality of life in obese subjects and nonobese subjects and to find out the Vitamin D (VD) status and correlations between obesity and control groups and also according to their quality of life scores.Materials and Method: The study was carried out between May and October 2013 which is the period of VD synthesis in Turkey. The participants of this study were volunteering individuals – obese and nonobese individuals defined according to the body mass index (BMI) – that did not receive any VD support in the last 1‑year and did not have any known chronic diseases. 1,25‑OH VD status and homeostatic model assessment insulin resistance (HOMA‑IR) values were evaluated.Results: The study population consisted of 39 individuals with normal weight (23 women, 16 men) and 66 individuals categorized as obese (51 women, 15 men). The difference in HOMA‑IR and VD values between the group of obese individuals and the group of nonobese individuals was significant (P < 0.001 vs. P <0.001). The median value of HOMA‑IR was higher in the obese group than in the nonobese group (P < 0.001) while the median value of VD was higher in the nonobese group than in the obese group (P < 0.001). The results regarding the relationship of BMI with HOMA‑IR and VD show that there was a positive correlation between HOMA‑IR and BMI (rs = 0.507; P < 0.001) and there was a negative correlation between HOMA‑IR and VD (rs = −0.316; P = 0.0001).Conclusion: Given serious diseases associated with low serum VD levels such as diabetes and cardiovascular disorders as well as low side effect incidence and low cost of VD treatment, it would be a reasonable approach to identify routine serum 25(OH) D and/or 1,25‑OH VD levels of obese patients and administer a treatment to patients with low levels of VD.Key words: 1,25‑OH Vitamin D, insulin resistance, obesit
The collision and snapping of cosmic strings generating spherical impulsive gravitational waves
The Penrose method for constructing spherical impulsive gravitational waves
is investigated in detail, including alternative spatial sections and an
arbitrary cosmological constant. The resulting waves include those that are
generated by a snapping cosmic string. The method is used to construct an
explicit exact solution of Einstein's equations describing the collision of two
nonaligned cosmic strings in a Minkowski background which snap at their point
of collision.Comment: 10 pages, 6 figures, To appear in Class. Quantum Gra
Can a Unruh Detector Feel a Cosmic String?
Unruh's detector calculation is used to study the effect of the defect angle
in a space-time with a cosmic string for both the excitation and
deexcitation cases. It is found that a rotating detector results in a non-zero
effect for both finite (small) and infinite (large) time
19 Dubious Ways to Compute the Marginal Likelihood of a Phylogenetic Tree Topology.
The marginal likelihood of a model is a key quantity for assessing the evidence provided by the data in support of a model. The marginal likelihood is the normalizing constant for the posterior density, obtained by integrating the product of the likelihood and the prior with respect to model parameters. Thus, the computational burden of computing the marginal likelihood scales with the dimension of the parameter space. In phylogenetics, where we work with tree topologies that are high-dimensional models, standard approaches to computing marginal likelihoods are very slow. Here, we study methods to quickly compute the marginal likelihood of a single fixed tree topology. We benchmark the speed and accuracy of 19 different methods to compute the marginal likelihood of phylogenetic topologies on a suite of real data sets under the JC69 model. These methods include several new ones that we develop explicitly to solve this problem, as well as existing algorithms that we apply to phylogenetic models for the first time. Altogether, our results show that the accuracy of these methods varies widely, and that accuracy does not necessarily correlate with computational burden. Our newly developed methods are orders of magnitude faster than standard approaches, and in some cases, their accuracy rivals the best established estimators
Journey to the Center of the Cookie Ecosystem: Unraveling Actors' Roles and Relationships
Web pages have been steadily increasing in complexity over time, including code snippets from several distinct origins and organizations. While this may be a known phenomenon, its implications on the panorama of cookie tracking received little attention until now. Our study focuses on filling this gap, through the analysis of crawl results that are both large-scale and fine-grained, encompassing the whole set of events that lead to the creation and sharing of around 138 million cookies from crawling more than 6 million webpages. Our analysis lets us paint a highly detailed picture of the cookie ecosystem, discovering an intricate network of connections between players that reciprocally exchange information and include each other's content in web pages whose owners may not even be aware. We discover that, in most webpages, tracking cookies are set and shared by organizations at the end of complex chains that involve several middlemen. We also study the impact of cookie ghostwriting, i.e., a common practice where an entity creates cookies in the name of another party, or the webpage. We attribute and define a set of roles in the cookie ecosystem, related to cookie creation and sharing. We see that organizations can and do follow different patterns, including behaviors that previous studies could not uncover: for example, many cookie ghostwriters send cookies they create to themselves, which makes them able to perform cross-site tracking even for users that deleted third-party cookies in their browsers. While some organizations concentrate the flow of information on themselves, others behave as dispatchers, allowing other organizations to perform tracking on the pages that include their content
Degradation Issues in Solid Oxide Cells During High Temperature Electrolysis
Idaho National Laboratory (INL) is performing high-temperature electrolysis (HTE) research to generate hydrogen using solid oxide electrolysis cells (SOECs). The project goals are to address the technical and degradation issues associated with the SOECs. This paper provides a summary of ongoing INL and INL-sponsored activities aimed at addressing SOEC degradation. These activities include stack testing, post-test examination, degradation modeling, and issues that need to be addressed in the future. Major degradation issues relating to solid oxide fuel cells (SOFC) are relatively better understood than those for SOECs. Some of the degradation mechanisms in SOFCs include contact problems between adjacent cell components, microstructural deterioration (coarsening) of the porous electrodes, and blocking of the reaction sites within the electrodes. Contact problems include delamination of an electrode from the electrolyte, growth of a poorly (electronically) conducting oxide layer between the metallic interconnect plates and the electrodes, and lack of contact between the interconnect and the electrode. INL's test results on HTE using solid oxide cells do not provide clear evidence as to whether different events lead to similar or drastically different electrochemical degradation mechanisms. Post-test examination of the SOECs showed that the hydrogen electrode and interconnect get partially oxidized and become nonconductive. This is most likely caused by the hydrogen stream composition and flow rate during cooldown. The oxygen electrode side of the stacks seemed to be responsible for the observed degradation because of large areas of electrode delamination. Based on the oxygen electrode appearance, the degradation of these stacks was largely controlled by the oxygen electrode delamination rate. Virkar et al. [19-22] have developed a SOEC model based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic nonequilibrium. This model is under continued development. It shows that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential within the electrolyte. The chemical potential within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just under the oxygen electrode (anode)/electrolyte interface, leading to electrode delamination. This theory is being further refined and tested by introducing some electronic conduction in the electrolyte.United States. Department of Energy. Office of Energy Efficiency and Renewable EnergyUnited States. Office of the Assistant Secretary for Nuclear Energ
Self-Duality in D <= 8-dimensional Euclidean Gravity
In the context of D-dimensional Euclidean gravity, we define the natural
generalisation to D-dimensions of the self-dual Yang-Mills equations, as
duality conditions on the curvature 2-form of a Riemannian manifold. Solutions
to these self-duality equations are provided by manifolds of SU(2), SU(3), G_2
and Spin(7) holonomy. The equations in eight dimensions are a master set for
those in lower dimensions. By considering gauge fields propagating on these
self-dual manifolds and embedding the spin connection in the gauge connection,
solutions to the D-dimensional equations for self-dual Yang-Mills fields are
found. We show that the Yang-Mills action on such manifolds is topologically
bounded from below, with the bound saturated precisely when the Yang-Mills
field is self-dual. These results have a natural interpretation in
supersymmetric string theory.Comment: 9 pages, Latex, factors in eqn. (6) corrected, acknowledgement and
reference added, typos fixe
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