mehmet sayan - Academia.edu (original) (raw)

Papers by mehmet sayan

Microsystem Technologies

In this study, the static displacement behaviour of a three-layer axisymmetric circular piezoelec... more In this study, the static displacement behaviour of a three-layer axisymmetric circular piezoelectric unimorph actuator subjected to voltage and uniform pressure loads for different mechanical and geometric properties of layers was investigated. The closed-analytical model of piezoelectric actuator based on the classical laminated thin plate theory was performed. Kirchhoff’s thin plate theory for the mathematical model in closed form of the actuator was utilized. The superposition of transverse and lateral deflections expressions was used to obtain the displacement equation of the piezoelectric actuator. Then, the analytical model solutions were compared by finite element model solutions. It was observed that the results obtained from analytical model and finite element analysis were sufficiently compatible with each other. The effects of nondimensional physical and mechanical properties on the static deflection performance of the piezoelectric actuator were discussed using the analytical model. According to the results obtained, the physical and mechanical properties of the actuator had significant effects on the actuator displacement. Therefore, the results obtained in this study can be used to optimize the performance of the circular piezoelectric actuator.

International Journal of Oral and Maxillofacial Surgery, 2004

Descending necrotizing mediastinitis is a potentially fatal condition which may occur seldom as a... more Descending necrotizing mediastinitis is a potentially fatal condition which may occur seldom as a consequence of oral infections. This report describes the management of a patient with mediastinitis due to an infected dentigerous cyst.

Anesthesiology, 2000

Background: Ventilator-associated pneumonia is the leading nosocomial infection in critically ill... more Background: Ventilator-associated pneumonia is the leading nosocomial infection in critically ill patients. The frequency of ventilator-associated pneumonia caused by multidrug-resistant bacteria has increased in recent years, and these pathogens cause most of the deaths attributable to pneumonia. The authors, therefore, evaluated factors associated with selected multidrug-resistant ventilator-associated pneumonia in critical care patients. Methods: The authors prospectively recorded potential risk factors at the time of intensive care unit admission. An endotracheal aspirate was obtained in all patients who met clinical criteria for pneumonia. Patients were considered to have ventilator-associated pneumonia only when they met the clinical criteria and aspirate culture was positive for bacteria 48 h or more after initiation of mechanical ventilation. Pediatric patients were excluded. Adult patients with ventilator-associated pneumonia were first grouped as "early-onset" (< 5 days) and "late-onset," determined by episodes of ventilator-associated pneumonia, and then, assigned to four groups based on the bacteria cultured from their tracheal aspirates: Pseudomonas aeruginosa, Acinetobacter baumanii, methicillin-resistant staphylococci, and all others. The first three bacteria were considered to be multidrug resistant, whereas the others were considered to be antibiotic susceptible. Potential risk factors were evaluated with use of univariate statistics and multivariate regression. Results: Among 486 consecutive patients admitted during the study, 260 adults underwent mechanical ventilation for more than 48 h. Eighty-one patients (31%) experienced 99 episodes of ventilator-associated pneumonia, including Pseudomonas (33 episodes), methicillin-resistant staphylococci (17 episodes), Acinetobacter (9 episodes), and nonresistant bacteria (40 episodes). Sixty-six of these episodes were early onset and 33 episodes were late onset. Logistic regression analysis identified three factors significantly associated with early-onset ventilator-associated pneumonia caused by any one of the multidrugresistant bacterial strains: emergency intubation (odds ratio, 6.4; 95% confidence interval, 2.0-20.2), aspiration (odds ratio, Additional material related to this article can be found on the ANESTHESIOLOGY Web site. Go to the following address, click on Enhancements Index, and then scroll down to find the appropriate article and link. http://www.anesthesiology.org

Infection control and hospital epidemiology, 1996

Patients admitted during the study period to the Sharp Memorial Hospital intensive-care units who... more Patients admitted during the study period to the Sharp Memorial Hospital intensive-care units who required mechanical ventilation were followed prospectively; 15 (10.4%) of 145 acquired ventilator-associated pneumonia (VAP). Duration of prior oral or nasal intubation and H2 receptor antagonists use were longer among patients who developed VAP than among those who did not. Prior cefazolin use was associated with a higher rate of VAP (11 of 63 [17%] versus 4 of 82 [5%], P = .01).

International Journal of Oral and Maxillofacial Surgery, 2003

Breast Cancer …, 2003

Introduction Breast cancer is a hormone-dependent neoplasm. Conflict-ing results regarding the cl... more Introduction Breast cancer is a hormone-dependent neoplasm. Conflict-ing results regarding the clinical correlation between breast cancer and thyroid diseases have been reported in the liter-ature. Many studies showed that thyroid diseases are common among women with ...

Anesthesia & Analgesia, 2005