Bulunan: 375 Adet 0.002 sn
Koleksiyon [5]
Tam Metin [1]
Yazar [20]
Yayın Türü [9]
Konu Başlıkları [20]
Yayın Tarihi [1]
Dergi Adı [20]
Yayıncı [20]
Dil [3]
Yazar Departmanı [1]
Understanding the behaviour of infinite ladder circuits

C. Ucak | K. Yegin

Article | 2008 | European Journal of Physics29 ( 6 ) , pp.1201 - 1209

Infinite ladder circuits are often encountered in undergraduate electrical engineering and physics curricula when dealing with series and parallel combination of impedances, as a part of filter design or wave propagation on transmission lines. The input impedance of such infinite ladder circuits is derived by assuming that the input impedance does not change when a new block of impedance is added. However, the impedance derived from this assumption may lead to incorrect conclusions if it is not treated carefully. Sometimes, in the literature, the input impedance behaviour of infinite ladder circuits is referred to as a paradox, leav . . .ing students and educators in doubt. This study intends to clarify this confusion and help to better comprehend the behaviour of the input impedance of infinite ladder circuits. © 2008 IOP Publishing Ltd Daha fazlası Daha az

Sarcoidosis and coronary bypass surgery: a case report.

C.E. Yildiz | M.U. Ergenoglu | H. Yerebakan | A.I. Ekici | N. Selcuk | D.S. Kucukaksu

Article | 2008 | The heart surgery forum11 ( 5 ) , pp.1201 - 1209

Sarcoidosis, a chronic granulomatous disease with unknown etiology and pathogenesis, affects the skin and many other organs and has a course characterized by remissions and relapses. We describe a patient with sarcoidosis, which we diagnosed retrospectively after we had difficulties in harvesting the left internal thoracic artery because of giant and disseminated mediastinal lymphadenopathies on the anterior thoracic wall during urgent coronary artery bypass surgery.

Novel diagnostic autoantibodies in rheumatoid arthritis

Yanik, B. | Külcü, D.G.

Review | 2008 | Romatizma23 ( 3 ) , pp.97 - 99

Early diagnosis and early treatment can prevent joint damage in rheumatoid arthritis (RA); but the lack of appropriate diagnostic criteria hinders early diagnosis. There are not many disease-specific serological markers for the diagnosis of the disease. Highly sensitive and specific markers are needed in the early stages of the disease. The autoantibodies which probably play an importanat role in the pathogenesis of RA and have increasingly been examined in recent years, will be reviewed, discussed, and examples given of the work done.

Melatonin: A suitable agent for depression associated with stroke?

Cam, E. | Yulug, B. | Cengiz, N. | Poelkin, E. | Isyk, D. | Bakar, M. | Kilic, E.

Letter | 2008 | Journal of Neuropsychiatry and Clinical Neurosciences20 ( 4 ) , pp.498 - 500

[No abstract available]

Wildtype Elk-1, but not a SUMOylation mutant, represses egr-1 expression in SH-SY5Y neuroblastomas

Demir, O. | Aksan Kurnaz, I.

Article | 2008 | Neuroscience Letters437 ( 1 ) , pp.20 - 24

Elk-1, an ETS domain transcription factor of the TCF (ternary complex factor) subfamily, is known to be involved in the regulation of immediate-early genes such as c-fos upon mitogen activation, and thus commonly implied in cell proliferation. Early growth response-1, Egr-1, which was known to be an immediate-early gene, has recently been shown to be pro-apoptotic for SH-SY5Y neuroblastoma cells. In that respect, it was not clear whether Elk-1 would activate or repress from this promoter, since Elk-1 is mostly associated with proliferation and not apoptosis. In this study, we wanted to address whether Elk-1 activates or represses eg . . .r-1 promoter in neuroblastoma cells, and using a combination of RNA interference and reporter analyses, we present evidence that egr-1 gene is repressed by Elk-1 in normally cycling SH-SY5Y neuroblastoma cell line in a SUMO (small ubiquitin-related modifier)-dependent manner, a potential mechanism used by these cells to bypass apoptosis. © 2008 Elsevier Ireland Ltd. All rights reserved Daha fazlası Daha az

Malignant fibrous histiocytoma of the larynx in a patient with neurofibromatosis type 1

Pata, Y.S. | Ünal, M. | Polat, A.

Article | 2008 | B-ENT4 ( 2 ) , pp.117 - 120

Malignant fibrous histiocytoma of the larynx in a patient with neurofibromatosis type 1. Problem: Soft tissue sarcomas are rare malignancies in the head and neck region. Malignant fibrous histiocytoma is one of the most common types of head and neck soft-tissue sarcomas. Neurofibromatosis type 1 (NF1), or von Recklinghausen disease, is an autosomal dominant condition characterized by the development of multiple neurofibromas that can transform into aggressive sarcomas. Case report: We present an unusual case of malignant fibrous histiocytoma originating from the right vocal fold of the larynx associated with NF1 and discuss its hist . . .opathological and clinical features in light of the current literature. Conclusion: Because of their increased risk for malignancy, patients with NF1 should be carefully monitored for the development of additional neoplasms. Our experience supports the use of conservative surgery for treating limited lesions of laryngeal malignant fibrous histiocytoma Daha fazlası Daha az

Use of vaterite and calcite in forming calcium phosphate cement scaffolds

Tas, A.C.

Conference Object | 2008 | Ceramic Engineering and Science Proceedings28 ( 9 ) , pp.135 - 150

A series of novel orthopedic calcium phosphate (CaP+CaCO3) cements have been developed. The common point in these cements was that they all utilized single-phase CaCO3 (calcite or vaterite) in their powder components. The major phase in the end-product of these cements was carbonated, Ca-deficient, apatitic calcium phosphate, together with some varying amounts of unreacted CaCO3. Calcite powders used were needle-like or acicular in shape, whereas the vaterite powders were monodisperse, and spherical or ellipsoidal in shape. A new method for synthesizing spheroidal vaterite powders has also been developed. Setting solutions for calci . . .te-based cement scaffolds were prepared by acid-base neutralization of concentrated H3PO 4 and NaOH. 0.5 M phosphate buffer solution was used to transform precipitated vaterite powders into CaP at 37° to 70°C. Setting solutions possessed pH values ranging from 3 to 7.4 at room temperature. Resultant cements were micro- (5 to 50 micron pores) and macroporous (200 to 700 micron pores). In the macroporous cements, total porosity was variable from 20 to 45%. Setting times of those cements were adjustable over the range of 12 to 25 minutes. Compressive strengths of these cements varied from 2 to 3 MPa, depending on their porosity. CaP+CaCO3 cements thus obtained had relatively high surface areas (30 to 85 m2/g) whose surfaces were covered with nanocrystallites similar in size to the nanoplatelets found in biological collagen-calcium phosphate composites. Cement scaffolds were characterized by XRD, FTIR, SEM, ICP-AES, surface area and compressive strength measurements Daha fazlası Daha az

Ovarian enlargement associated with massive oedema

Eren, F. | Aydin, Ö. | Gök, N. | Eren, B. | Çomunoglu, N. | Çomunoglu, C.

Article | 2008 | Journal of the Pakistan Medical Association58 ( 1 ) , pp.43 - 45

Massive ovarian oedema is a rare entity described as accumulation of oedema fluid within the ovarian stroma, separating normal follicular structures. Our case was a 27-year-old woman who presented with a large solid pelvic mass after recurrent episodes of self-limited abdominal pain. On physical examination, she had left abdominal tenderness with minimal rebound and guarding. With a diagnosis of malignant ovarian tumor, an exploratory laparotomy was done and a twisted ovarian mass was found which was excised completely. Histopathological evaluation of the mass revealed massive oedema of the ovary. Massive ovarian oedema should be su . . .spected in women at the fertile age range with solid enlargement of the ovary Daha fazlası Daha az

Efficacy of treatment with a kinaesthetic ability training device on balance and mobility after stroke: A randomized controlled study

Gok, H. | Geler-Kulcu, D. | Alptekin, N. | Dincer, G.

Article | 2008 | Clinical Rehabilitation22 ( 10.11.2020 ) , pp.922 - 930

Objective: To investigate whether the addition of a kinaesthetic ability training device could enhance the effect of a conventional rehabilitation programme on balance and mobility in hemiparetic patients late after stroke. Design: Randomized, controlled, assessor-blinded trial. Setting: The rehabilitation ward of a university hospital. Thirty hemiparetic patients (mean age (SD) of 57.4 (8.1) years) late after stroke (mean time since stroke (SD) 545.2 (99.9) days) were assigned randomly to an experimental or a control group. Interventions: The control group (n = 15) participated in a conventional rehabilitation programme. The experi . . .mental group (n = 15) participated in balance training with a kinaesthetic ability training device in addition to a conventional rehabilitation programme for four weeks, five days a week. Outcome measures: Kinaesthetic ability training static and dynamic balance indices, balance and lower extremity subscores of the Fugl-Meyer Stroke Assessment Instrument (FMA), total motor and locomotor subitem scores of the Functional Independence Measure (FIM) were evaluated at baseline and after treatment. Results: The experimental group had greater improvement in measures of balance including static (P = 0.045) and dynamic balance index (P = 0.001) and FMA balance score (P = 0.001) than the control group. No between-group differences were detected in subscore of FMA, total motor and locomotor subscores of FIM. There were significant improvements in balance subscores of FMA, static and dynamic balance indexes in the experimental group and in sub-item scores of FIM and lower extremity scores of FMA in both groups. Conclusion: Kinaesthetic ability trainingin addition to a conventional rehabilitation programme is effective in improving balance late after stroke. However, this improvement is not reflected in individual functional status. © 2008 SAGE Publications Daha fazlası Daha az

The mechanism of the late preconditioning effect of 3-nitropropionic acid

Basgut, B. | Aypar, E. | Basgut, E. | Akın, K.O. | Kılıc, N. | Cakıcı, I.

Article | 2008 | Archives of Pharmacal Research31 ( 10 ) , pp.1257 - 1263

The aim of the present study was to investigate the mechanism of effect of 3-nitropropionic acid-(3-NP) induced late preconditioning in rat heart. For this purpose 20-30 min before 3-NP (20 mg/kg, i.p.) injection, the rats were treated intraperitoneally with 5-hydroxydecanoate (40 mg/kg, 5-HD, mitochondrial K ATP -channel blocker), L-NAME (100 mg/kg, NOS inhibitor), N-2-mercaptopropionylglycine (100 mg/kg, MPG, free radical scavenger), or superoxide dismutase+catalase (10000+10000 IU/kg, SOD+CAT). Control rats received saline only without 3-NP pretreatment. After two days, hearts were isolated and perfused at a constant pressure in . . .a Langendorff apparatus. 15-min global ischemia followed by 30-min reperfusion was applied to all hearts. Pretreatment of 3-NP significantly reduced infarct size, creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH) levels, and incidence of ventricular tachycardia (VT) compared with the control group receiving saline only. 5-HD, L-NAME, MPG, or SOD+CAT treatment statistically reversed 3-NP-induced reduction in infarct size. Although CK-MB, LDH levels, and incidence of VT were also reduced by L-NAME, MPG, or SOD+CAT treatment, only 5-HD significantly inhibited beneficial effects of 3-NP on all of the parameters above. These results showed that mito-K ATP channels play a pivotal role in late preconditioning effect of 3-NP in the isolated rat heart. However, other mediators such as reactive oxygen species and NO may be, at least in part, involved in mechanisms of this effect. © 2008 The Pharmaceutical Society of Korea Daha fazlası Daha az

The influence of spatial frequency in partial spatial erasure of holographic diffraction gratings within LiNbO3: Fe

R. Ince | H. Yukselici | A.T. Ince | A.V. Tunc

Article | 2008 | Optics and Lasers in Engineering46 ( 11 ) , pp.842 - 847

The effect of spatial frequency on partial spatial erasure of a hologram within a photorefractive crystal, lightly doped LiNbO3, was studied by capturing its reconstructed image on a digital camera at times varying from 40 s to 420 min after storage. The image's constituent spatial frequencies (6.2-62.3/cm) at these times were studied. Using a capacitor discharge model, lower spatial frequencies (6.2-41.6/cm) discharge exponentially after 180 min, the maximum space-charge field was found to occur for a median spatial frequency of 34.6/cm. Higher spatial frequencies charge continuously. Features oscillating at -2 mm/s were superimpos . . .ed on all frequencies >27.7/cm, evolving quadratically to a maximum amplitude at the spatial frequency of 48.5/cm before decaying. It is thought that the refractive-index field stored within the photorefractive crystal caused focussing of the read-out beam leading to the generation of a spatial soliton. © 2008 Elsevier Ltd Daha fazlası Daha az

Genotoxic effects of PCB 52 and PCB 77 on cultured human peripheral lymphocytes

Sandal, S. | Yılmaz, B. | Carpenter, D.O.

Article | 2008 | Mutation Research - Genetic Toxicology and Environmental Mutagenesis654 ( 1 ) , pp.88 - 92

Polychlorinated biphenyls (PCBs) are known to be carcinogenic, but the mechanisms of this action are uncertain. Most, but not all, studies have concluded that PCBs are not directly mutagenic, and that much if not all of the carcinogenic activity resides in the fraction of the PCB mixture that contains congeners with dioxin-like activity. The present study was designed to determine genotoxic effects of an ortho-substituted, non-coplanar congener, 2,2',5,5'-tetrachlorobiphenyl (PCB 52), and a non-ortho-substituted coplanar congener with dioxin-like activity, 3,3',4,4'-tetrachlorobiphenyl (PCB 77) on cultured human peripheral lymphocyt . . .es. DNA damage was assessed by use of the comet assay (alkaline single-cell gel electrophoresis). After cell cultures were prepared, test groups were treated with different concentrations of PCB 52 (0.2 and 1 µM) and PCB 77 (1 and 10 µM) for 1 h at 37 °C in a humidified carbon dioxide incubator, and compared to a DMSO vehicle control group. The cells were visually classified into four categories on the basis of extent of migration such as undamaged (UD), low damage (LD), moderate damage (MD) and high damage (HD). The highest concentration of PCBs 52 and 77 significantly increased DNA breakage in human lymphocytes (p < 0.001). Our results indicate that both the non-coplanar PCB 52 and coplanar PCB 77 cause DNA damage, and that the ortho-substituted congener was significantly more potent than the dioxin-like coplanar congener. © 2008 Elsevier B.V. All rights reserved Daha fazlası Daha az

6698 sayılı Kişisel Verilerin Korunması Kanunu kapsamında yükümlülüklerimiz ve çerez politikamız hakkında bilgi sahibi olmak için alttaki bağlantıyı kullanabilirsiniz.

Bu site altında yer alan tüm kaynaklar Creative Commons Alıntı-GayriTicari-Türetilemez 4.0 Uluslararası Lisansı ile lisanslanmıştır.