325 research outputs found

    Supersymmetric approach to exactly solvable systems with position-dependent effective masses

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    We discuss the relationship between exact solvability of the Schr\"{o}dinger equation with a position-dependent mass and the ordering ambiguity in the Hamiltonian operator within the frame of supersymmetric quantum mechanics. The one-dimensional Schr\"{o}dinger equation, derived from the general form of the effective mass Hamiltonian, is solved exactly for a system with exponentially changing mass in the presence of a potential with similar behaviour, and the corresponding supersymmetric partner Hamiltonians are related to the effective-mass Hamiltonians proposed in the literature.Comment: 12 pages article in LaTEX (uses standard article.sty). Please check http://www1.gantep.edu.tr/~ozer for other studies of Nuclear Physics Group at University of Gaziantep. [arXiv admin note: excessive overlap with quant-ph/0306065 and "Supersymmetric approach to quantum systems with position-dependent effective mass" by A. R. Plastino, A. Rigo, M. Casas, F. Garcias, and A. Plastino - Phys. Rev. A 60, 4318 - 4325 (1999)

    Primjena autologne fibrinske membrane obogaćene trombocitima (PRF) u liječenju dubokih čireva rožnice u pasa

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    The aim of this study was to evaluate the clinical efficacy of a platelet-rich fibrin (PRF) membrane, which is considered to be a new alternative surgical method in the treatment of vision-threatening corneal ulcers in dogs. Fourteen dogs (17 eyes) of various breeds and ages with deep corneal ulcers were treated surgically with a PRF membrane transplantation. The corneal ulcer of all the patients was closed with an autologous platelet-rich fibrin membrane. In the first 10 days after the operation, it was observed that the fibrin membrane partially melted, and corneal epithelialization and granulation tissue occurred in and around the ulcer area due to the graft material. Pain was significantly relieved, and conjunctival inflammation was noticeably improved. From the 20th day after the surgery, the granulation tissue was gradually cleaned. It was determined that all the eyes had vision. The most common complications after surgery were corneal pigmentation and fibrosis of varying severity. The use of autologous fibrin membranes is a safe and effective surgical alternative for the closure and healing of corneal ulcers. Our findings show that the autologous platelet-rich fibrin membrane is useful and effective in treating canine corneal deep ulcers.Čirevi rožnice mogu oštetiti vid u pasa. Cilj je ovog istraživanja bio procijeniti kliničku učinkovitost fibrinske membrane obogaćene trombocitima (PRF), kao nove alternative kirurških metoda u liječenju čireva rožnice. Četrnaest pasa (17 očiju) različitih pasmina i dobi, s dubokim čirevima rožnice liječeno je kirurški transplantacijom. Čir na rožnici u svih je pacijenata bio zatvoren autolognom fibrinskom membranom obogaćenom trombocitima. Prvih 10 dana nakon kirurškog zahvata uočeno je da se fibrinska membrana parcijalno talila, dok se na čiru i oko njega pojavilo epitelizacijsko i granulacijsko tkivo zbog graft materijala. Bol je znatno ublažena, a upala konjunktive osjetno smanjena. Od 20. dana nakon kirurškog zahvata granulacijsko je tkivo postupno očišćeno. Pokazalo se da je svim psima vraćen vid. Najčešće su komplikacije nakon kirurškog zahvata bile pigmentacija rožnice i fibroza različita stupnja. Rezultati istraživanja pokazuju da je autologna fibrinska membrana obogaćena trombocitima sigurna, korisna i učinkovita kirurška alternativa u liječenju dubokih čireva rožnice u pasa

    Evaluating expert advice in forecasting: users' reactions to presumed vs. experienced credibility

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    YesIn expert knowledge elicitation (EKE) for forecasting, the perceived credibility of an expert is likely to affect the weighting attached to their advice. Four experiments have investigated the extent to which the implicit weighting depends on the advisor’s experienced (reflecting the accuracy of their past forecasts), or presumed (based on their status) credibility. Compared to a control group, advice from a source with a high experienced credibility received a greater weighting, but having a low level of experienced credibility did not reduce the weighting. In contrast, a high presumed credibility did not increase the weighting relative to a control group, while a low presumed credibility decreased it. When there were opportunities for the two types of credibility to interact, a high experienced credibility tended to eclipse the presumed credibility if the advisees were non-experts. However, when the advisees were professionals, both the presumed and experienced credibility of the advisor were influential in determining the weight attached to the advice

    CD28 between tolerance and autoimmunity: The side effects of animal models [version 1; referees: 2 approved]

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    Regulation of immune responses is critical for ensuring pathogen clearance and for preventing reaction against self-antigens. Failure or breakdown of immunological tolerance results in autoimmunity. CD28 is an important co-stimulatory receptor expressed on T cells that, upon specific ligand binding, delivers signals essential for full T-cell activation and for the development and homeostasis of suppressive regulatory T cells. Many in vivo mouse models have been used for understanding the role of CD28 in the maintenance of immune homeostasis, thus leading to the development of CD28 signaling modulators that have been approved for the treatment of some autoimmune diseases. Despite all of this progress, a deeper understanding of the differences between the mouse and human receptor is required to allow a safe translation of pre-clinical studies in efficient therapies. In this review, we discuss the role of CD28 in tolerance and autoimmunity and the clinical efficacy of drugs that block or enhance CD28 signaling, by highlighting the success and failure of pre-clinical studies, when translated to humans

    Higher Dimensional Cylindrical or Kasner Type Electrovacuum Solutions

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    We consider a D dimensional Kasner type diagonal spacetime where metric functions depend only on a single coordinate and electromagnetic field shares the symmetries of spacetime. These solutions can describe static cylindrical or cosmological Einstein-Maxwell vacuum spacetimes. We mainly focus on electrovacuum solutions and four different types of solutions are obtained in which one of them has no four dimensional counterpart. We also consider the properties of the general solution corresponding to the exterior field of a charged line mass and discuss its several properties. Although it resembles the same form with four dimensional one, there is a difference on the range of the solutions for fixed signs of the parameters. General magnetic field vacuum solution are also briefly discussed, which reduces to Bonnor-Melvin magnetic universe for a special choice of the parameters. The Kasner forms of the general solution are also presented for the cylindrical or cosmological cases.Comment: 16 pages, Revtex. Text and references are extended, Published versio

    The association of self-esteem, depression and body satisfaction with obesity among Turkish adolescents

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    <p>Abstract</p> <p>Background</p> <p>The purpose of this study was to determine the prevalence of overweight and obesity and to examine the effects of actual weight status, perceived weight status and body satisfaction on self-esteem and depression in a high school population in Turkey.</p> <p>Methods</p> <p>A cross-sectional survey of 2101 tenth-grade Turkish adolescents aged 15–18 was conducted. Body mass index (BMI) was calculated using weight and height measures. The overweight and obesity were based on the age- and gender-spesific BMI cut-off points of the International Obesity Task Force values. Self-esteem was measured using the Rosenberg Self-Esteem Scale, and depression was measured using Children's Depression Inventory. Logistic regression analysis was used to examine relationships among the variables.</p> <p>Results</p> <p>Based on BMI cut-off points, 9.0% of the students were overweight and 1.1% were obese. Logistic regression analysis indicated that (1) being male and being from a higher socio-economical level were important in the prediction of overweight based on BMI; (2) being female and being from a higher socio-economical level were important in the prediction of perceived overweight; (3) being female was important in the prediction of body dissatisfaction; (4) body dissatisfaction was related to low self-esteem and depression, perceived overweight was related only to low self-esteem but actual overweight was not related to low self-esteem and depression in adolescents.</p> <p>Conclusion</p> <p>The results of this study suggest that school-based adolescents in urban Turkey have a lower risk of overweight and obesity than adolescents in developed countries. The findings of this study suggest that psychological well-being of adolescents is more related to body satisfaction than actual and perceived weight status is.</p

    Neuroendocrine tumors presenting with thyroid gland metastasis: a case series

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    <p>Abstract</p> <p>Introduction</p> <p>Autopsy series have shown that metastasis to the thyroid gland has occurred in up to 24% of patients who have died of cancer. Neuroendocrine tumors may metastasize to thyroid gland.</p> <p>Case presentations</p> <p>Case 1 was a 17-year-old Turkish woman who was referred from our Endocrinology Department for a thyroidectomy for treatment of neuroendocrine tumor metastasis. She was treated with a bilateral total thyroidectomy. Histopathological examination results were consistent with a neuroendocrine tumor; neoplastic cells showed strong immunoreactivity to chromogranin A and synaptophysin, but the immunohistochemical profile was inconsistent with medullary thyroid carcinoma in that the tumor was negative for calcitonin, carcinoembryonic antigen, and thyroid transcription factor-1.</p> <p>Case 2 was a 54-year-old Turkish woman who presented with a 3-cm nodule on her right thyroid lobe. She had undergone surgery for a right lung mass four years previously. After a right pneumonectomy, thymectomy and lymph node dissection, a typical carcinoid tumor was diagnosed. Under ultrasonographic guidance, fine needle aspiration biopsy of her right thyroid pole nodule was performed and the biopsy was compatible with a neuroendocrine tumor metastasis. She was treated with a bilateral total thyroidectomy. Histopathological examination indicated three nodular lesions, 5 cm and 0.4 cm in diameter in her right lobe and 0.1 cm in diameter in her left lobe. The tumors were consistent with a neuroendocrine phenotype, showing strong immunoreactivity to chromogranin A and synaptophysin.</p> <p>Conclusion</p> <p>Thyroid nodules detected during follow-up of neuroendocrine tumor patients should be thoroughly investigated. A fine needle aspiration biopsy of the thyroid confirms the diagnosis in most cases and leads to appropriate management of those patients and may prevent unnecessary treatment approaches.</p

    Neustonic versus epiphytic bacteria of eutrophic lake and their biodegradation ability on deltamethrin

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    This study evaluated biodegradation of the insecticide deltamethrin (1 μg l−1) by pure cultures of neustonic (n = 25) and epiphytic (n = 25) bacteria and by mixed cultures (n = 1), which consisted of a mixture of 25 bacterial strains isolated from the surface microlayer (SM ≈ 250 μm) and epidermis of the Common Reed (Phragmites australis, (Cav.) Trin. ex Steud.) growing in the littoral zone of eutrophic lake Chełmżyńskie. Results indicate that neustonic and epiphytic bacteria are characterized by a similar average capacity to degrade deltamethrin. After a 15-day incubation, bacteria isolated from the surface microlayer reduced the initial concentration of deltamethrin by 60%, while the average effectiveness of the bacteria found on the Common Reed equaled 47%

    A retrospective comparison of allogeneic peripheral blood stem cell and bone marrow transplantation results from a single center: A focus on the incidence of graft-vs.-host disease and relapse

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    To detect the effect of the stem cell source, allogeneic peripheral blood stem cell transplantations (alloPBSCTs) performed between 1995 and 1997 from human leukocyte antigen (HLA)-identical siblings in 40 patients with acute and chronic hematological disorders were compared with a historical group of 40 patients with similar variables who had received allogeneic bone marrow transplants (alloBMTs) between 1993 and 1995. Patients in both groups were identical except that both the recipient and the donor ages were, on average, higher in the alloPBSCT group (26 vs. 36 [p = 0.005] and 27 vs. 32 [p = 0.024], respectively). Patients received similar therapy excluding posttransplant granulocyte colony-stimulating factor administration (97% in alloBMT vs. 12.5% in alloPBSCT). The median time to reach neutrophil counts &gt;0.5×109/L and platelet counts &gt;20×109/L was 13 and 14 days, respectively, in patients receiving alloPBSCTs compared with 19 and 27 days in patients receiving alloBMTs (p = 0.0014 and p = 0.0002). The alloPBSCT group required similar transfusions of red blood cells or platelets. The incidence of grade II-IV acute graft-vs.-host disease (aGVHD) was similar in both groups. However, chronic GVHD (cGVHD) of all grades developed in 78.1% of patients in the alloPBSCT group after a median follow-up period of 12.5 (range 0.5-34) months. In alloBMT recipients, cGVHD of all grades developed in 21.4% after a median follow-up period of 38 (range 0.5-62) months (p = 0.00001). Day 100 transplant-related mortality was also similar: 20% (8 of 40) in the alloBMT patients and 17.5% (7 of 40) in the alloPBSCT group. Although not statistically significant, a relatively higher relapse rate occurred in the alloBMT group (21.4 vs. 10.7%). The estimated disease-free survival in month 24 was 51.3% for alloBMT and 54.6% for alloPBSCT, and the estimated overall survival in month 24 was 56.1% for alloBMT and 64.6% for alloPBSCT. In conclusion, this retrospective comparison suggests that alloPBSCT from HLA-identical donors is associated with faster engraftment, fewer transfusions, and no greater incidence of aGVHD, but a high incidence of cGVHD
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