Ali Mert

International disaster relief planning with fuzzy credibility

As a consequence of more extensive collaboration between countries, the need for better humanitarian relief assistance has become a significant challenge to the international community. In case of a disaster exceeding the national response capacity of the affected country, donor countries provide the relief items, which are then consolidated at collection points to be shipped to points of delivery in the stricken country. After the items are transported to the point of delivery, the responsible authority in distributing aids to vulnerable populations then becomes the national relief agencies. In this context, we propose an international relief planning model that can handle the uncertain information while maximizing the credibility of the international agencies in the most cost efficient way.

Perception of anatomical structures in digitally filtered and conventional panoramic radiographs: a clinical evaluation

OBJECTIVES The aims of the study were to compare subjective image quality of clinical images obtained with a storage phosphor plate (SPP)-based digital and conventional film-based panoramic system for the visualization of various anatomical structures and to evaluate the effect of various processing algorithms on image interpretation. METHODS Panoramic radiographs were taken in 42 patients both with film and with a SPP system. SPP images were treated with shadow, sharpen, negative, greyscale sigma and greyscale exponential filters. Four observers subjectively evaluated films and unfiltered and filtered SPP images for the visibility of anatomical structures with various radiodensities as well as for overall image quality on a three-point rating scale. The statistical methods used were Kruskal-Wallis, odds ratio analysis and Cohens kappa. RESULTS No statistically significant difference was found between film and unfiltered digital images except for low-contrast structures (P > 0.05). Film images were preferred for the visibility of low-contrast structures (P < 0.05). Best overall image quality was obtained with sharpened images (P < 0.05) followed by films and unfiltered digital images. Among all filtered images, sharpened ones received the highest ratings for the visibility of all anatomical structures (P < 0.05). The intra- and interobserver agreement ranged between moderate and substantial and between fair and moderate, respectively. CONCLUSIONS Film and unfiltered SPP-based panoramic images performed equally well in terms of overall quality; however, films were best for the perception of low-contrast structures. The sharpening filter may be recommended for enhancing SPP panoramic images to improve the visual perception of most of the anatomical structures as well as overall quality.

Effect of tube potential and image receptor on the detection of natural proximal caries in primary teeth

The aim of this study was to assess the detection of proximal caries in primary teeth at three different tube potentials using Ektaspeed films, storage phosphor plates (SPPs), and a charge-coupled device (CCD). Fifty-three extracted human primary molars with natural proximal caries were radiographed with three different imaging modalities—Digora Optime SPP system, RVGui CCD system, and Ektaspeed films—at 50-, 65-, and 70-kV tube potentials. Three observers scored the resultant images for the presence or absence of caries. The definitive diagnosis was determined by stereomicroscopic assessment. The diagnostic accuracy for each imaging modality was expressed as the area under the receiver operating characteristic curves (Az). Differences among the Az values were assessed using two-way ANOVA and t tests. Kappa was used to measure inter- and intra-observer agreement. Higher accuracy was found for SPPs compared to film and CCD images at all tube potentials. Accuracy was significantly different only at 50-kV tube setting in favor of SPPs (p < 0.05). Inter- and intra-observer agreement was high for all systems. A SPP system can be recommended for dental peadodontic clinics particularly with 50-kV tube potential for the diagnosis of proximal caries since further advantages include the elimination of chemical processing, image enhancement, and a better low-contrast detectability performance.

The effect of delayed scanning of storage phosphor plates on occlusal caries detection

OBJECTIVE The aim of this study was to determine (1) the effect of various scan delays on pixel intensity measurements and (2) the diagnostic accuracy of occlusal caries detection. METHODS 72 non-cavitated extracted human permanent molar teeth with sound and carious occlusal surfaces were radiographed using the DIGORA® storage phosphor plates (SPPs) (Soredex Corporation, Helsinki, Finland). Plates were scanned immediately and 10 min, 30 min, 60 min and 120 min after exposure. Three different plates were used for each scan delay. An aluminium (Al) wedge was used to evaluate the change in mean grey values (MGVs) for scan delays. Diagnostic accuracy for occlusal caries detection was performed by scoring all the digital images. The true presence of caries was determined by stereomicroscopy. Comparison of MGVs of the Al wedge for immediate and delayed scans was made using repeated measures analysis of variance (ANOVA) and Tukey-Kramer tests. The accuracy was expressed as the area under the receiver operating characteristics curves (A(z)). A(z)s were compared using two-way ANOVA and t-tests. Kappa was used to measure inter and intraobserver agreement. RESULTS The mean A(z)s of immediately scanned plates were higher than the A(z)s of plates scanned with four different delays (p < 0.05). The A(z) of immediately scanned images was significantly higher than the A(z)s of images with 60 min and 120 min scan delays (p < 0.05) but not for 10 min and 30 min delays (p > 0.05). MGVs of immediately scanned plates were significantly higher than the plates scanned with four different delays (p < 0.05). Agreement decreased with increasing scan delays. CONCLUSION Scanning of DIGORA SPPs should not be delayed beyond 30 min for accurate occlusal caries diagnosis.

A Learning Algorithm for Level Sets Weights in Weighted Level-based Averaging Method

The method which we call the Weighted Averaging Based on Levels (WABL) can be used to calculate the average representative of a fuzzy number. It utilizes weight coefficients for the level sets as well as the sides of a fuzzy number. We have developed an algorithm to obtain these coefficients. The most remarkable feature of this algorithm is that it makes use of the decision maker’s (DM) aggregation strategy.

Diagnostic accuracy of proximal enamel subsurface demineralization and its relationship with calcium loss and lesion depth

OBJECTIVE The aim of this study was to determine the relationship between the amount of calcium loss, lesion depth, and the accuracy of storage phosphor plate (SPP) and film radiographs for the detection of artificial proximal demineralization. METHODS Standard enamel windows of extracted premolars were exposed to a demineralizing solution for 60 h, 80 h, 100 h and 120 h. Solutions were analysed for calcium concentration by atomic absorption spectrometer and the lesion depths were calculated by a specific formula. All teeth were radiographed with SPPs and F-speed films before and after acid application. Images were evaluated by five observers. Stereomicroscopic and scanning electron microscopic (SEM) observations were carried out to visualize enamel surfaces after acid exposure. Receiver operating characteristic analysis was used for diagnostic accuracy (A(z)). A(z)s were compared with factorial analysis of variance and t-tests. The relationship between A(z)s and lesion depths was determined with Pearsons correlation test. RESULTS Strong positive correlation was found between A(z)s of both radiographic methods and lesion depths. No difference was found between the A(z)s of two radiographic systems for any of the demineralization durations (p > 0.05). Pair-wise comparisons revealed no significant difference in A(z)s of SPPs (p > 0.05), while significant differences were obtained for the A(z)s of films for different demineralization periods (p < 0.05). Stereomicroscopic and SEM observations confirmed demineralizations from superficial to deeper layers of enamel. CONCLUSION Subsurface enamel demineralization was not accurately detectable with either storage phosphor plates or F-speed films. The amount of calcium loss and the depth of demineralization have a strong relationship with diagnostic accuracy with a significant effect particularly on F-speed films.

Design of dimensionally stable composites using efficient global optimization method

Dimensionally stable material design is an important issue for space structures such as space laser communication systems, telescopes, and satellites. Suitably designed composite materials for this purpose can meet the functional and structural requirements. In this paper, it is aimed to design the dimensionally stable laminated composites by using efficient global optimization method. For this purpose, the composite plate optimization problems have been solved for high stiffness and low coefficients of thermal and moisture expansion. Some of the results based on efficient global optimization solution have been verified by genetic algorithm, simulated annealing, and generalized pattern search solutions from the previous studies. The proposed optimization algorithm is also validated experimentally. After completing the design and optimization process, failure analysis of the optimized composites has been performed based on Tsai–Hill, Tsai–Wu, Hoffman, and Hashin–Rotem criteria.

On the profust reliabilities of consecutive k-out-of-n systems

System reliability concept is a very popular topic among scientific research areas. Systems may be classified based on their structures such as linear and circular, based on their evaluation characteristics such as fuzzy and nonfuzzy states and based on working principles such as F and G systems. Linear and circular system distinction is originated from ordering difference of components. System and/or component states can be evaluated as fuzzy and nonfuzzy. If system and component states are both evaluated as nonfuzzy, then the reliability of such a system is considered as conventional reliability. On the contrary, if system or component states are evaluated as fuzzy, then reliability of such a system is considered as fuzzy reliability. While the working principle is defined with respect to the number of failed components for an F system, it is defined with respect to the number of working components for a G system. A consecutive k-out-of-n:F system composes of a sequence of n ordered components such that the system is failed if and only if at least k consecutive components in the system are failed. Similarly, consecutive k-out-of-n:G system composes of a sequence of n ordered components such that the system works if and only if at least k consecutive components in the system work. In this study, we research the profust (states of components are evaluated as nonfuzzy and state of system is evaluated as fuzzy) reliabilities of consecutive k-out-of-n:F and G systems considering both linear and circular sequence of n components. The reliabilities of these systems are evaluated for independent and identically distributed components. Easy-to-use formulas for the reliabilities of these systems are obtained using the distribution of some run statistics. In order to use these formulas, the working probability of a component at any time is sufficient. Some numerical results and figures are also presented to acquire some information about the reliabilities of related systems and to compare performance differences between conventional and profust reliabilities of systems considered in this study.

Diagnostic accuracy of Digora Optime storage phosphor plates for proximal subsurface demineralization: effect of different exposure times

OBJECTIVE The aim of this study was to compare the diagnostic accuracy of F-speed film and storage phosphor plate (SPP) exposed with different exposure times for the detection of artificial enamel subsurface demineralization. STUDY DESIGN Standard enamel windows of extracted premolars were exposed to a demineralizing solution. All teeth were radiographed before and after acid application with F-speed films and SPPs. Films were exposed for 0.25 seconds and SPPs were exposed using 4 exposure times. Receiver operating characteristic analysis was used for diagnostic accuracy (A(z)). RESULTS Significant differences were obtained among A(z)s of 0.08- versus 0.12-seconds and 0.10- versus 0.12-second exposed SPPs (P < .05). A(z)s of films were higher than the SPPs exposed with 0.08, 0.10, and 0.12 seconds (P < .05). No difference was found between the A(z)s of the 2 systems when SPPs were exposed for 0.16 seconds (P > .05). CONCLUSIONS Diagnostic accuracy of films and SPPs was not impaired when exposure time was 36% reduced for the latter; however, diagnosis was impaired when reduced 52%.

GENERAL APPROACH TO THE TREATMENT OF ODONTOGENIC ABSCESSES AND COST ANALYSIS

Purpose: The purpose of this study was to evaluate the relationships between age, gender, symptoms, treatment, length of hospital stay and hospital cost in a group of patients with severe odontogenic infection who has been admitted within the last 6 years. Subjects and Methods: This study was carried out on 30 patients who had been treated in Ege University, Faculty of Medicine, Otolaryngology Department with the diagnosis of odontogenic abscess. Variables such as age, gender, symptoms, systemic disease, imaging techniques, treatment modalities, hospital length of stay and hospital cost were analyzed statistically. Results: There were 12 female and 18 male patients and their mean age was 39 ± 19.78 years. Antibiotics were used in all subjects and their abscesses were mostly drained surgically. The mean hospital length of stay was 8.1 days. There was a statistically significant relationship with the presence of systemic disease and hospital length of stay variables (p=0.017). Conclusion: The cost for treatment of severe odontogenic infections in inpatient units is high in hospitals. Therefore, preventive and routine dental care should be given importance.