Başkent University

About: Başkent University is a education organization based out in Ankara, Turkey. It is known for research contribution in the topics: Transplantation & Population. The organization has 4652 authors who have published 10380 publications receiving 143117 citations. The organization is also known as: Başkent Üniversitesi.

Shadow and quasinormal modes of a rotating loop quantum black hole

Abstract: In this paper, we construct an effective rotating loop quantum black hole (LQBH) solution, starting from the spherical symmetric LQBH by applying the Newman-Janis algorithm modified by Azreg-A\"{\i}nou's noncomplexification procedure, and study the effects of loop quantum gravity (LQG) on its shadow. Given the rotating LQBH, we discuss its horizon, ergosurface, and regularity as $r\ensuremath{\rightarrow}0$. Depending on the values of the specific angular momentum $a$ and the polymeric function $P$ arising from LQG, we find that the rotating solution we obtained can represent a regular black hole, a regular extreme black hole, or a regular spacetime without horizon (a non-black-hole solution). We also study the effects of LQG and rotation, and show that, in addition to the specific angular momentum, the polymeric function also causes deformations in the size and shape of the black hole shadow. Interestingly, for a given value of $a$ and inclination angle ${\ensuremath{\theta}}_{0}$, the apparent size of the shadow monotonically decreases, and the shadow gets more distorted with increasing $P$. We also consider the effects of $P$ on the deviations from the circularity of the shadow, and find that the deviation from circularity increases with increasing $P$ for fixed values of $a$ and ${\ensuremath{\theta}}_{0}$. Additionally, we explore the observational implications of $P$ in comparing with the latest Event Horizon Telescope observation of the supermassive black hole, M87*. The connection between the shadow radius and quasinormal modes in the eikonal limit as well as the deflection of massive particles are also considered.

The value of Tzanck smear test in diagnosis of erosive, vesicular, bullous, and pustular skin lesions.

Abstract: Background Tzanck smear is generally used for the diagnosis of the pemphigus group of autoimmune bullous diseases and mucocutaneous herpesvirus infections. There are only a few studies in the literature investigating its diagnostic value. Objectives We aimed to investigate Tzanck smear findings and to determine the diagnostic value of this test in moist (erosive, vesicular, bullous, and pustular) skin lesions. We also aimed to develop an algorithmic approach for the diagnosis of these types of skin lesions according to the Tzanck smear findings. Methods Samples were stained with May-Grunwald-Giemsa and evaluated by the same dermatologist. In some patients, methylene blue and Gram staining or direct immunofluorescence examinations were additionally performed. In all of the study cases, after the evaluation of clinical and laboratory findings (including, when appropriate, potassium hydroxide examination; viral serology; bacterial and fungal cultures; histopathology; direct and indirect immunofluorescence; patch testing), the definite diagnosis was established. We also determined the sensitivity and the specificity of certain Tzanck smear findings. Results Tzanck smear was performed in a total of 400 patients with moist skin lesions. The sensitivities of multinucleated giant cells and acantholytic cells in herpetic infections, dyskeratotic acantholytic cells and cocci in bullous impetigo, pseudohyphae in candidiasis, acantholytic cells in pemphigus and more than 10 tadpole cells (magnification ×100) in spongiotic dermatitis were 84.7%, 92%, 100%, 100%, and 81.5%, respectively. Limitations Because Tzanck smears were evaluated by the same dermatologist, no comment could be made regarding the interobserver reliability of this test and how the level of experience with this technique might affect the results. Also, the sensitivity and the specificity of Tzanck smear test findings for certain diseases could not be calculated because of an insufficient number of patients. Conclusion The Tzanck smear test is an inexpensive, useful, and an easy diagnostic tool for certain skin diseases.

Displaced supracondylar humeral fractures in children: open reduction vs. closed reduction and pinning.

Abstract: In the literature the best results for pediatric supracondylar humerus fractures have been achieved by closed reduction and wire fixation. However, in these reports the patient group of open reduction and pinning contained the patients who had had previous ineffective closed reduction trials. This retrospective study compared open and closed reduction with pinning, in which the first group of patients was all consecutively treated with open reduction. The study included 99 children with displaced extension-type supracondylar fractures of humerus who had complete follow-up. Open reduction patients had not had a previous attempted closed reduction. Open reduction and pinning were performed through a posteromedial incision in the first 44 patients and closed reduction and pinning in the subsequent 55 patients. Mean duration surgery was 15 h with open reduction and 17 h with closed reduction. Mean follow up was 35 months with the open reduction and 21 months with closed reduction. Humeral-ulnar angle was compared to the contralateral elbow, clinical flexion deficiency and extension lag, and complications were evaluated. At the latest follow-up the open group had an average of 5.1° valgus change and the closed group 3.6° valgus change in humeral-ulnar angle compared to their uninvolved elbow. Average flexion deficiency was 8.61° in the open and 5.25° in the closed group. Average extension lag was 6.23° in the open and 0.6° in the closed group. Functional results were satisfactory in 71% of patients in the open and 93% of those in the closed reduction group. Cosmetic results were satisfactory in 95% of both groups. Closed reduction and pinning is superior to open reduction and pinning for the treatment of pediatric supracondylar humerus fractures. In the case of technical insufficiencies open reduction and pinning through a posteromedial incision is an alternative treatment for decreasing the surgical time and complications. Complications was not caused in either group by the delayed surgical timing compared to reports in the literature.

Qualitative and Semiquantitative Evaluations of Solid Breast Lesions by Sonoelastography

Abstract: OBJECTIVES Our purpose was to determine whether the combination of a qualitative elasticity scoring method and a semiquantitative strain index method by sonoelastography is useful for differentiating between benign and malignant breast masses. METHODS Seventy-eight lesions in 71 consecutive patients with solid breast masses (62 benign and 16 malignant) were prospectively included in this study. For each lesion, B-mode sonographic and sonoelastographic images were obtained. After elasticity scores had been determined with a 5-point scoring method, strain indices of the lesions were calculated using a same-level and normal-appearing breast region as an internal reference by means of strain ratio measurement. The findings were compared with histopathologic findings. With the use of receiver operating characteristic curves, the diagnostic performances of the elasticity scoring and strain index methods were determined. RESULTS The mean scores ± SD on sonoelastography were 2.69 ± 0.59 for benign lesions and 3.75 ± 0.68 for malignant lesions. The mean stiffness index values were 2.03 ± 2.67 for benign lesions and 5.97 ± 4.45 for malignant lesions. The areas under the curves were 0.864 for 5-point scoring and 0.840 for the strain index. Sensitivity and specificity were 80% and 95%, respectively, for 5-point scoring, 87.5% and 72.6% for B-mode sonography, and 80% and 93% for the strain index when a cutoff point of 3.52 was used. A semiquantitative evaluation using the strain index did not contribute to the qualitative scoring evaluation. CONCLUSIONS After 5-point scoring with sonoelastography, additional measurement with the strain index is not mandatory for differentiating between benign and malignant breast masses.