Classification and Spectral Evolution of Outbursts of Aql X-1

We present a broad classification of all outbursts detected with the All-Sky Monitor (ASM) on the Rossi X-Ray Timing Explorer (RXTE) and the Monitor of All Sky X-Ray Image (MAXI) of Aql X-1. We identify three types of outbursts; long-high, medium-low, and short-low, based on the duration and maximum flux. We analyse the trends in the "phase-space" of flux-derivative versus flux to demonstrate the differences in the three identified outburst types. We present a spectral analysis of the observations of Aql X-1 performed by the Proportional Counter Array (PCA) onboard RXTE during the 2000 and 2011 outbursts of the long-high class and the 2010 outburst of the medium-low class. We model the source spectrum with a hybrid thermal/non-thermal hot plasma emission model (EQPAIR in XSPEC, Coppi 2000) together with a Gaussian component to model the Fe K_alpha emission line. We construct time histories of the source flux, the optical depth of the corona (tau), the seed photon temperature (kT_bb) and the hard state compactness (l_h) for these three outbursts. We show that the physical parameters of either classes reach the same values throughout the outbursts, the only difference being the maximum flux. We discuss our results in the terms of modes of interaction of the star with the disc and size of the disc kept hot by irradiation. We conclude that irradiation is the dominant physical process leading to the different classes of outbursts.Comment: MNRAS accepted. 12 pages, 9 figures, 3 table

Partial accretion in the propeller stage of low mass X-ray binary Aql X--1

Aql X--1 is one of the most prolific low mass X-ray binary transients (LMXBTs) showing outbursts almost annually. We present the results of our spectral analyses of RXTE/PCA observations of the 2000 and the 2011 outbursts. We investigate the spectral changes related to the changing disk-magnetosphere interaction modes of Aql X--1. The X-ray light curves of the outbursts of LMXBTs typically show phases of fast rise and exponential decay. The decay phase shows a "knee" where the flux goes from the slow decay to the rapid decay stage. We assume that the rapid decay corresponds to a weak propeller stage at which a fraction of the inflowing matter in the disk accretes onto the star. We introduce a novel method for inferring, from the light curve, the fraction of the inflowing matter in the disk that accretes onto the NS depending on the fastness parameter. We determine the fastness parameter range within which the transition from the accretion to the partial propeller stage is realized. This fastness parameter range is a measure of the scale-height of the disk in units of the inner disk radius. We applied the method to a sample of outbursts of Aql X--1 with different maximum flux and duration times. We show that different outbursts with different maximum luminosity and duration follow a similar path in the parameter space of accreted/inflowing mass flux fraction versus fastness parameter.Comment: 16 pages, 5 figures, 5 tables, accepted for publication in Ap

AN ANALYSIS OF THE REASONING SKILLS OF PRE-SERVICE TEACHERS IN THE CONTEXT OF MATHEMATICAL THINKING

The aim of this study is to address and analyse pre-service teachers’ mathematical reasoning skills in relation to mathematical thinking processes. For these purposes, pre-service teachers’ mathematical reasoning skills namely generalising/abstraction/modelling, ratiocination, development and creative thinking skills and the relationships among these skills are examined. Apart from these, it is explored whether grade level and gender have an effect on the application of these skills. The study is based on a mixed method research design and is carried out with 197 pre-service teachers of different grade levels in the school of education of a public university. One of the data collection tools used in the study is mathematical thinking and reasoning skills test which was developed by Başaran (2011) and comprises 21 open-ended questions on real-life problems. The second one is the Mathematical Reasoning Skills and Indicators developed by the researchers in the light of a study by Alkan and Taşdan (2011). Content analysis is performed on the data gathered from the pilot study conducted as the first step of the data analysis and the content of the quantitative data analysis is defined. As the second step, some parametric and non-parametric tests are utilized using the SPSS 15.0 software. As a result of the study, it has been revealed that pre-service teachers’ scores on generalising/abstraction/modelling and ratiocination skills are close to average whereas their scores on development and creative thinking skills are below average. It has also been concluded that all the relationships among pre-service teachers’ reasoning skills are significant and that correlations among the skills which are associated with stages that follow one another are stronger than the others. Another result of the study is that, in relation to the gender variable, there is a significant difference among the scores concerning generalising/abstraction/modelling and ratiocination skills, yet there are not any significant differences among the development and creative thinking skills scores. In relation to the grade variable, on the other hand, there aren’t any significant differences among the scores concerning generalising/abstraction/modelling (GAM) and reasoning (R) and improving (İ) skills, yet there are significant differences among the creative thinking skills scores of freshman and sophomore pre-service teachers and among those of the sophomore and junior pre-service teachers.Results of the present study are discussed in relation to the relevant literature and some recommendations for future studies pertaining to the subject and to learning environment quality are presented.  Article visualizations

Development of a Stabilizing Adaptive Feedback Control System for Helicopter Gun Turrets

This study introduces a stabilizing controller design for a helicopter gun turret system using an adaptive backstepping control approach. To model the gun turret system, a two-degree-offreedom manipulator dynamics is employed, which enables precise control over the weapon pointing mechanism. The proposed controller design utilizes an adaptive backstepping control strategy to ensure system stability and robustness against disturbances such as firing and other operational conditions. Additionally, the design includes an advanced feedback mechanism that dynamically adjusts to changes in the helicopter's flight dynamics, further enhancing control accuracy. Simulation results show the efficacy of the controller, achieving stable and precise control of the gun turret system. The study offers a simplified model to enhance the performance of helicopter gun turret systems, with potential applications in military ground and naval vehicles. The proposed controller design is a promising solution to improve the precision and stability of the gun turret system, contributing to safer and more efficient defense systems

Female Urethral Malignant Melanoma With Vesical Invasion: A Case Report

We report a 75-year-old female with a primary urethral malignant melanoma. A mass protruding from inside the urethra was detected on physical examination. Abdominopelvic magnetic resonance imaging revealed a mass extending from the urethra with dimensions of 4 × 2 cm, and periurethral heterogenous fatty planes consistent with infiltration. The histopathologic examination was consistent with HMB45(+) malignant melanoma. We performed cystourethrectomy and bilateral inguinal and pelvic lymphadenectomy in one session. The pathology report revealed primary malignant melanoma of the urethra invading the inferior bladder wall. The patient received no adjuvant therapy because of cardiopulmonary morbidities and the presence of multiple pulmonary metastases. The patient eventually died 13 months after surgery

DEMOGRAPHICS AND CHARACTERISTICS OF PATIENTS WITH TRAUMATIC BONE CYSTS: A RETROSPECTIVE REVIEW

Objectives:  The aim of this study was to evaluate the demographics and characteristics of the patients treated for traumatic bone cyst (TBC). Materials and Methods: A retrospective review was conducted to determine the radiological, clinical and demographic characteristics of patients with TBC who were surgically treated over a 2-year period using data retrieved from computerized databases. Results: The study sample consisted of 22 patients (24 lesions in total) with mean age of 22.9 years. All lesions were located in the mandible (16 in anterior mandible, 8 in posterior mandible) and diagnosed incidentally during routine dental examinations. There was no statistically significant difference between male and female patients in demographic characteristics. All patients were followed up for 6-18 months with uneventful healing. Conclusions: TBCs should be kept in mind during examination of radiolucent lesions of the mandible particularly in younger patients. Along with the histopathological examination, clinical and radiological findings, symptoms of the patients, and surgeon’s experience should be considered for a definitive diagnosis

Kalça kırıklı yaşlı Türk hasta grubunda bir ve iki yıllık mortaliteyi etkileyen faktörler

Amaç: Kalça kırıkları ileri yaşların fonksiyon kaybı ve ölüm ile sonuçlanabilen ciddi sağlık sorunlarındandır. Bu çalışmada amaç kalça kırığı sonrası yaşlı Türk hastalarda değişik risk faktörlerinin mortalite üzerine etkisini ortaya koymaktır. Hastalar ve Yöntemler: 2001-2006 yılları arasında kalça kırığı nedeniyle ameliyat edilmiş, 60 yaş ve üzeri, en az iki yıllık takibi olan 240 hastanın (ort. yaş 76.0±8.2) demografik verileri, ameliyat öncesi süreleri, anestezi ve ASA fiziksel durumu, başvuru albumin düzeyi ile ek morbiditeleri incelendi. Bulgular: Geliş albumin seviyesi 3.45±0.62 g/dl olarak bulundu. Yüz sekiz hastada (%45) albumin düşüklüğü vardı. Albumin düzeyine göre bir ve iki yıl mortalite oranı anlamlı değildi. Ameliyat öncesi yatış süreleri incelendiğinde; birinci yıl mortalitesi erkek hastalarda istatistiksel anlamlı yüksek bulunurken (p=0.015), ikinci yıl mortalitesi bulunmadı. ASA fiziksel skorları yüksek olan hastaların birinci yıl mortaliteleri ile korelasyonunun istatistiksel olarak anlamlı olduğu (p=0.002), ikinci yılda ise olmadığı (p=0.169) saptandı. Cinsiyet incelendiğinde, birinci yıl mortalitesi erkekler için yüksek bulundu (p=0.001). Sonuç: Yüksek ASA skorlarına ek morbiditeler nedeniyle yaşlı hastalarda sık karşılaşılmaktadır. Preoperatif hazırlık sürecinin ASA skoru yüksek olan hastalarda uzun olması nedeniyle ameliyat öncesi süre uzayabilmektedir. Kalça kırığı olan hastaların bir ve iki yıllık mortalite öngörüsünde ASA fiziksel durumu ve ameliyat öncesi gecikmenin önemli belirteçler olduğu görüşündeyiz.Objectives: Hip fractures are one of the most serious causes of impairment and death in the elderly. The aim of this study is to identify the effects of different risk factors on mortality after a hip fracture in elderly Turkish patients. Patients and Methods: Two-hundred forty patients (>60 years; mean age 76.0±8.2 years) who were operated for fracture of the hip from 2001 to 2006 were investigated. Demographic data, preoperative length of hospital stay, anesthesia type and ASA physical status, albumin level at admission and comorbidities were recorded. Results: Mean albumin level was 3.45±0.62 g/dl. Onehundred eight (45%) had hypoalbuminemia. The difference between mortality rates of normo- and hypoalbuminemic patients were not significant at one and two-year. According to preoperative length of stay; one-year mortality was significantly higher in male patients (p=0.015) while two-year mortality was not. One-year mortality was related with high ASA physical status scores (p=0.002) while two-year mortality was not (p=0.169). According to gender; one-year mortality was found higher in men (p=0.001). Conclusion: Due to comorbidities, high ASA scores are common in elderly patients. Since the preoperative evaluation in high ASA physical status is longer, this may prolong the preoperative hospital stay. Delay after admission and high ASA physical status are important predictors of mortality for elderly hip fracture patients