Showing papers by "Başkent University published in 2014"

Generating rotating regular black hole solutions without complexification

Abstract: We drop the complexification procedure from the Newman-Janis algorithm and introduce more physical arguments and symmetry properties, and we show how one can generate regular and singular rotating black hole and non-black-hole solutions in Boyer-Lindquist coordinates. We focus on generic rotating regular black holes and show that they are regular on the Kerr-like ring, but physical entities are undefined there. We show that rotating regular black holes have much smaller electric charges, and, with increasing charge, they turn into regular non-black-hole solutions well before their Kerr-Newman counterparts become naked singularities. No causality violations occur in the region inside a rotating regular black hole. The separability of the Hamilton-Jacobi equation for neutral particles is also carried out in the generic case, and the innermost boundaries of circular orbits for particles are briefly discussed. Other, but special, properties pertaining to the rotating regular counterpart of the Ay\'on-Beato--Garc\'{\i}a regular static black hole are also investigated.

Risk Assessment of Tuberculosis in Immunocompromised Patients. A TBNET Study

Abstract: Rationale: In the absence of active tuberculosis, a positive tuberculin skin test (TST) or interferon-γ release assay (IGRA) result defines latent infection with Mycobacterium tuberculosis, although test results may vary depending on immunodeficiency.Objectives: This study compared the performance of TST and IGRAs in five different groups of immunocompromised patients, and evaluated their ability to identify those at risk for development of tuberculosis.Methods: Immunocompromised patients with HIV infection, chronic renal failure, rheumatoid arthritis, solid-organ or stem-cell transplantation, and healthy control subjects were evaluated head-to-head by the TST, QuantiFERON-TB-Gold in-tube test (ELISA), and T-SPOT.TB test (enzyme-linked immunospot) at 17 centers in 11 European countries. Development of tuberculosis was assessed during follow-up.Measurements and Main Results: Frequencies of positive test results varied from 8.7 to 15.9% in HIV infection (n = 768), 25.3 to 30.6% in chronic renal failure (n =...

Criteria for a lean organisation: development of a lean assessment tool

Abstract: Lean principles have long been recognised as a competitive advantage. Although there are several measures for various aspects of lean production in the literature, there is no comprehensive measure for overall lean implementation in business firms. An appropriate measurement tool is needed to assess the effectiveness and efficiency of the lean implementation throughout the entire organisation. Based on lean research, a comprehensive tool called the leanness assessment tool (LAT) is developed, using both quantitative (directly measurable and objective) and qualitative (perceptions of individuals) approaches to assess lean implementation. The LAT measures leanness using eight quantitative performance dimensions: time effectiveness, quality, process, cost, human resources, delivery, customer and inventory. The LAT also uses five qualitative performance dimensions: quality, process, customer, human resources and delivery, with 51 evaluation items. The fuzzy method allows managers to identify improvement needs...

Timing of noninvasive ventilation failure: causes, risk factors, and potential remedies

Abstract: Identifying the predictors of noninvasive ventilation (NIV) failure has attracted significant interest because of the strong link between failure and poor outcomes. However, very little attention has been paid to the timing of the failure. This narrative review focuses on the causes of NIV failure and risk factors and potential remedies for NIV failure, based on the timing factor. The possible causes of immediate failure (within minutes to <1 h) are a weak cough reflex, excessive secretions, hypercapnic encephalopathy, intolerance, agitation, and patient-ventilator asynchrony. The major potential interventions include chest physiotherapeutic techniques, early fiberoptic bronchoscopy, changing ventilator settings, and judicious sedation. The risk factors for early failure (within 1 to 48 h) may differ for hypercapnic and hypoxemic respiratory failure. However, most cases of early failure are due to poor arterial blood gas (ABGs) and an inability to promptly correct them, increased severity of illness, and the persistence of a high respiratory rate. Despite a satisfactory initial response, late failure (48 h after NIV) can occur and may be related to sleep disturbance. Every clinician dealing with NIV should be aware of these risk factors and the predicted parameters of NIV failure that may change during the application of NIV. Close monitoring is required to detect early and late signs of deterioration, thereby preventing unavoidable delays in intubation.

The Effect of Instructional Techniques on Critical Thinking and Critical Thinking Dispositions in Online Discussion

Abstract: The aim of this research study was to explore the effect of instructional techniques on critical thinking and critical thinking dispositions in online discussion, based on triangulation design. Six Thinking Hats, Brainstorming, Role Playing, Socratic Seminar, and Anyone Here an Expert, were selected as an instructional techniques for online discussion. In the quantitative part, according to the results of ANOVA, except Socratic Seminar, there is no difference between groups in terms of scores of pre-tests and post-tests of critical thinking dispositions. In the qualitative part, according to the results of the analysis of critical thinking in online discussion, the Mixed Techniques group performed as having the best ability of critical thinking, the Anyone Here an Expert group was second and the Brainstorming group was third in terms of performing critical thinking ability in online discussion.

The Effect of Bone-Marrow-Derived Stem Cells and Adipose-Derived Stem Cells on Wound Contraction and Epithelization.

Abstract: Objective: The relationship between the wound contraction and levels of α-smooth muscle actin (α-SMA) has been revealed in different studies. We aimed to investigate the effects of mesenchymal stem cells (MSCs), mainly bone-marrow-derived stem cells (BSCs) and adipose-derived stem cells (ASCs), and find out the α-SMA, fibroblast growth factor (FGF), transforming growth factor beta, and vascular endothelial growth factor (VEGF) levels on an in vivo acute wound healing model after the application of MSCs. Approach: Four circular skin defects were formed on the dorsum of Fisher rats (n=20). The defects were applied phosphate-buffered saline (PBS), ASCs, BSCs, and patchy skin graft, respectively. The healing time and scar area were noted. Results: There was a statistical decrease in the healing time in ASC, BSC, and skin graft groups (p<0.05). However, the scar was smaller in the PBS group (p<0.05). The α-SMA levels were statistically lower in ASC, BSC, and graft groups (p<0.05). The FGF levels were statistic...

Adipose-Derived Stem Cells as a Novel Tool for Future Regenerative Medicine

Abstract: Stem cell-based therapies for the repair and regeneration of damaged tissues and organs offer a paradigm shift that may provide alternative therapeutic solutions for a number of diseases. The use of either embryonic stem cells or induced pluripotent stem cells in clinical situations may be still limited due to cell behaviors, ethical considerations, and genetic manipulation, even though these cells are theoretically highly beneficial. Adipose-derived stem cells (ASCs) seem to be an ideal population of stem cells for practical regenerative medicine since they are plentiful, of autologous tissue origin and thus non-immunogenic, and are more available due to minimal ethical considerations. Furthermore, recent basic research and preclinical studies have revealed that the use of ASCs in regenerative medicine is not limited to mesodermal components, but extends to both ectodermal and endodermal tissues and organs, even though ASCs are mesodermal in origin. This chapter will describe the biology of ASCs and their proliferation and differentiation capacities, and will summarize the current preclinical and clinical data from a variety of medical fields on the use of ASCs in regenerative medicine.

Long-Term Oral Nutrition Supplementation Improves Outcomes in Malnourished Patients With Chronic Kidney Disease on Hemodialysis

Abstract: Background: There is no consensus on the type, time of initiation, or duration of use of enteral nutrition in patients with chronic kidney disease (CKD). This study aimed to compare the effects of a renal-specific oral nutrition supplement (RS-ONS) and a standard recommended nutrition regime on biochemical and nutrition markers in malnourished patients with CKD on hemodialysis. Methods: Sixty-two malnourished patients with CKD, divided into experimental (RS-ONS; n = 32; mean [SD] age, 62.0 [11.3] years; 55.2% female) and control (CON; n = 30; mean [SD] age, 57.2 [12.3] years; 31% female) groups, were evaluated for anthropometric, biochemical, and inflammatory parameters. Results: Mean (SD) serum albumin levels were significantly increased in the RS-ONS group from 3.5 (0.3) g/ dL at baseline to 3.7 (0.2) g/dL at 6 months (P = .028). Significantly fewer patients had serum albumin levels of <3.5 g/dL after month 6. Dry weight of patients significantly increased in the RS-ONS but decreased in the CON groups (P < .001 for each). Percent change from baseline revealed negative results for bioelectrical impedance analysis (P < .001) in the CON group. Malnutrition inflammation score at 6 months (P = .006) and erythropoietin (EPO) dose requirements were higher in the CON group (P = .012). Conclusions: Our findings indicate that consuming RS-ONS improves serum albumin and anthropometric measures, as well as reduces EPO dose, in patients with CKD. (JPEN J Parenter Enteral Nutr. XXXX;xx:xx-xx)

Remedies for recurrent implantation failure.

Abstract: In vitro fertilization (IVF) is expensive, time consuming, and the most successful treatment of fertility; however, in general the cumulative chance of having a live birth with the treatment is still around 40%. Many couples still remain unsuccessful after several IVF attempts, causing deep impact on quality of life, and each failed cycle causing a financial burden. Several adjuvant therapies have been used along with IVF to increase the pregnancy rates for women with repeated implantation failure. Testing of adjuvant therapies in properly conducted randomized controlled trials is rarely done so that potential benefits and risks are unlikely to be clearly presented to patients and clinicians. In this review, we assessed the effects of adjuvants, such as growth hormone, androgens, and glucocorticoids to enhance oocyte number and quality; sildenafil, low-dose aspirin, heparin, corticosteroids, granulocyte colony-stimulating factor, endometrial injury, intrauterine injection of human chorionic gonadotropin, and intrauterine administration of autologous peripheral blood mononuclear cells to improve poor endometrial response; antioxidants, complementary and alternative medicine modalities, such as Chinese herbal medicine and acupuncture; and assisted hatching and preimplantation genetic screening to correct embryonic factors.

Validation of Montreal Cognitive Assessment and Discriminant Power of Montreal Cognitive Assessment Subtests in Patients With Mild Cognitive Impairment and Alzheimer Dementia in Turkish Population.

Abstract: Montreal Cognitive Assessment (MoCA) is a new cognitive tool developed for screening mild cognitive impairment (MCI). The authors examined validity of MoCA and discriminating power of subtests in a Turkish population comprising of 474 participants (246 healthy controls, 114 subjects with MCI and 114 subjects with dementia). The ANCOVAs showed that age and education had a main effect on MoCA scores. Cut scores were computed according to different education levels. The overall cut-off values for MCI and dementia were found to be lower compared to western studies. MoCA was found to have good internal consistency. The subtests most useful in discriminating MCI from healthy controls were recall, visuospatial and language, while in discriminating dementia from MCI were visuospatial, orientation and attention subtests. The results demonstrated that MoCA is a valid and reliable instrument in screening MCI, and compared with the MMSE, MoCA was proved to have superior sensitivity and specificity in detecting MCI.

Surgical and interventional management of complications caused by acute pancreatitis

Abstract: Acute pancreatitis is one of the most common gastrointestinal disorders worldwide. It requires acute hospitalization, with a reported annual incidence of 13 to 45 cases per 100,000 persons. In severe cases there is persistent organ failure and a mortality rate of 15% to 30%, whereas mortality of mild pancreatitis is only 0% to 1%. Treatment principles of necrotizing pancreatitis and the role of surgery are still controversial. Despite surgery being effective for infected pancreatic necrosis, it carries the risk of long-term endocrine and exocrine deficiency and a morbidity and mortality rate of between 10% to 40%. Considering high morbidity and mortality rates of operative necrosectomy, minimally invasive strategies are being explored by gastrointestinal surgeons, radiologists, and gastroenterologists. Since 1999, several other minimally invasive surgical, endoscopic, and radiologic approaches to drain and debride pancreatic necrosis have been described. In patients who do not improve after technically adequate drainage, necrosectomy should be performed. When minimal invasive management is unsuccessful or necrosis has spread to locations not accessible by endoscopy, open abdominal surgery is recommended. Additionally, surgery is recognized as a major determinant of outcomes for acute pancreatitis, and there is general agreement that patients should undergo surgery in the late phase of the disease. It is important to consider multidisciplinary management, considering the clinical situation and the comorbidity of the patient, as well as the surgeons experience.

From static to rotating to conformal static solutions: Rotating imperfect fluid wormholes with(out) electric or magnetic field

Abstract: We derive a shortcut stationary metric formula for generating imperfect fluid rotating solutions, in Boyer-Lindquist coordinates, from spherically symmetric static ones. We explore the properties of the curvature scalar and stress-energy tensor for all types of rotating regular solutions we can generate without restricting ourselves to specific examples of regular solutions (regular black holes or wormholes). We show through examples how it is generally possible to generate an imperfect fluid regular rotating solution via radial coordinate transformations. We derive rotating wormholes that are modeled as imperfect fluids and discuss their physical properties that are independent on the way the stress-energy tensor is interpreted. A solution modeling an imperfect fluid rotating loop black hole is briefly discussed. We then specialize to the recently discussed stable exotic dust Ellis wormhole emerged in a source-free radial electric or magnetic field, generate its, conjecturally stable, rotating counterpart which turns out to be an exotic imperfect fluid wormhole and determine the stress-energy tensor of both the imperfect fluid and the electric or magnetic field.

From static to rotating to conformal static solutions: rotating imperfect fluid wormholes with(out) electric or magnetic field

Abstract: We derive a shortcut stationary metric formula for generating imperfect fluid rotating solutions, in Boyer–Lindquist coordinates, from spherically symmetric static ones. We explore the properties of the curvature scalar and stress–energy tensor for all types of rotating regular solutions we can generate without restricting ourselves to specific examples of regular solutions (regular black holes or wormholes). We show through examples how it is generally possible to generate an imperfect fluid regular rotating solution via radial coordinate transformations. We derive rotating wormholes that are modeled as imperfect fluids and discuss their physical properties. These are independent on the way the stress–energy tensor is interpreted. A solution modeling an imperfect fluid rotating loop black hole is briefly discussed. We then specialize to the recently discussed stable exotic dust Ellis wormhole as emerged in a source-free radial electric or magnetic field, and we generate its, conjecturally stable, rotating counterpart. This turns out to be an exotic imperfect fluid wormhole, and we determine the stress–energy tensor of both the imperfect fluid and the electric or magnetic field.

Attributes of cancer patients admitted to the emergency department in one year

Abstract: RESULTS: The study included 240 (58.8%) males and 168 (41.2%) females with a median age of 57.9 years (range 19–87). Regarding cancer staging, 266 patients (65.3%) had metastatic disease and 142 (34.7%) had local and loco-regional disease. The hospitalization rate was 59.6%. The most common symptoms were shortness of breath (23.2%), pain (17.8%), fever (14.2%), and nausea/vomiting (14.4%). The most common cancer sites were the lung (32.5%), gastrointestinal system (25.4%), and breast (9.3%). The initial evaluation determined progressive disease (42.4%), chemotherapy effects (20.7%), infections (17.2%), radiotherapy effects (4.7%), extravasation (1.8%), anemia (1.4%), and unknown (11.3%). During follow up, 191 (46.8%) patients died after admission to the ED. The 1-year overall survival of all patients was 7.3 months. CONCLUSIONS: Symptom management in cancer patients is a complex multifaceted concern for the emergency physician. Because of the increasing prevalence of cancer patients, emergency physicians should develop consensus algorithms in collaboration with the relevant disciplines to manage the commonly encountered problems.

Etiology of hypopituitarism in tertiary care institutions in Turkish population: analysis of 773 patients from Pituitary Study Group database.

Abstract: Hypopituitarism in adult life is commonly acquired and the main causes are known as pituitary tumors and/or their treatments. Since there are new insights into the etiology of hypopituitarism and presence of differences in various populations, more studies regarding causes of hypopituitarism are needed to be done in different ethnic groups with sufficient number of patients. Therefore, we performed a multi-center database study in Turkish population investigating the etiology of hypopituitarism in 773 patients in tertiary care institutions. The study was designed and coordinated by the Pituitary Study Group of SEMT (The Society of Endocrinology and Metabolism of Turkey). Nineteen tertiary reference centers (14 university hospitals and 5 training hospitals) from the different regions of Turkey participated in the study. It is a cross-sectional database study, and the data were recorded for 18 months. We mainly classified the causes of hypopituitarism as pituitary tumors (due to direct effects of the pituitary tumors and/or their treatments), extra-pituitary tumors and non-tumoral causes. Mean age of 773 patients (49.8 % male, 50.2 % female) was 43.9 ± 16.1 years (range 16-84 years). The most common etiology of pituitary dysfunction was due to non-tumoral causes (49.2 %) among all patients. However, when we analyze the causes according to gender, the most common etiology in males was pituitary tumors, but the most common etiology in females was non-tumoral causes. According to the subgroup analysis of the causes of hypopituitarism in all patients, the most common four causes of hypopituitarism which have frequencies over 10 % were as follows: non-secretory pituitary adenomas, Sheehan's syndrome, lactotroph adenomas and idiopathic. With regard to the type of hormonal deficiencies; FSH/LH deficiency was the most common hormonal deficit (84.9 % of the patients). In 33.8 % of the patients, 4 anterior pituitary hormone deficiencies (FSH/LH, ACTH, TSH, and GH) were present. Among all patients, the most frequent cause of hypopituitarism was non-secretory pituitary adenomas. However, in female patients, present study clearly demonstrates that Sheehan's syndrome is still one of the most important causes of hypopituitarism in Turkish population. Further, population-based prospective studies need to be done to understand the prevalence and incidence of the causes of hypopituitarism in different countries.

Subtrochanteric Shortening in Total Hip Arthroplasty: Biomechanical Comparison of Four Techniques

Abstract: Safe reduction of the femoral head into the true acetabulum requires a certain amount of femoral shortening in patients with high dislocation of the hip. In subtrochanteric shortening applications, to reduce complications it is necessary to maintain a stable fixation at the osteotomy line. The purpose of this study is to investigate frequently used methods from a biomechanical point of view. Four osteotomy groups were created with composite femurs to investigate subtrochanteric osteotomies; transverse, oblique, z-subtrochanteric and double Chevron. All loading tests were carried out with two implant types both with and without strut graft and cable fixation. No single inherent feature increasing the stability of the investigated osteotomy types was found. Additionally graft application did not have a significant contribution to stability.

Vitamin D deficiency is related to thyroid antibodies in autoimmune thyroiditis.

Abstract: Introduction It has been known that vitamin D has some immunomodulatory effects and in autoimmune thyroid diseases, vitamin D deficiency was more prevalent. In this study, our aim was to investigate the relationship between thyroid autoantibodies and vitamin D.

Effects of different orthodontic adhesives and resin removal techniques on enamel color alteration.

Abstract: Objective: To investigate the color alterations in enamel following the use of different orthodontic bonding resins and adhesive residue–removal burs. Materials and Methods: Metal brackets were bonded to extracted human premolars (n = 175) by using an etch-and-rinse adhesive system, a self-etch adhesive system (SEP), or a resin-modified glass ionomer cement (RMGIC). After 24 hours of photoaging, the brackets were removed and the adhesive residue on the tooth surfaces was cleaned with either a tungsten carbide bur or a Stainbuster bur. Tooth colors were measured with a spectrophotometer at baseline, after adhesive removal, and after additional photoaging. Color evaluation was made, and color differences induced by photoaging were calculated. Statistical evaluation was made using the Kruskal-Wallis test and the Mann-Whitney U-test, with Bonferroni correction. Results: All specimens showed discoloration at varying levels. The highest color change was observed in the etch-and-rinse adhesive/tungste...

Determining the effectiveness of illustrated communication material for communication with intubated patients at an intensive care unit

Abstract: Communication with non-speaking patients in intensive care unit is stress for both nurse and patients. Semi-experimental study that took place at a University Hospital was to develop illustrated material for patient communication and determine its effectiveness. The study sample consisted of 90 intubated patients at the Adult Cardiovascular Intensive Care Unit who had undergone open heart surgery. The patients were divided into the intervention and control groups. Data analysis was with descriptive statistics and the χ(2) test. The illustrated communication material was stated to be helpful by 77.8% and partially helpful by 22.2% of the intervention group patients regarding the communication between the health-care staff and the patients. Control group patients had more difficulties communicating with the health-care staff. Illustrated communication material was an effective method in communicating with intubated patients.