Erdogan Gunel

A Bayesian approach to reliability prediction and assessment of component based systems

It is generally believed that component-based software development leads to improved application quality, maintainability and reliability. However most software reliability techniques model integrated systems. These models disregard systems internal structure, taking into account only the failure data and interactions with the environment. We propose a novel approach to reliability analysis of component-based systems. Reliability prediction algorithm allows system architects to analyze reliability of the system before it is built, taking into account component reliability estimates and their anticipated usage. Fully integrated with the UML, this step can guide the process of identifying critical components and analyze the effect of replacing them with the more/less reliable ones. Reliability assessment algorithm, applicable in the system test phase, utilizes these reliability predictions as prior probabilities. In the Bayesian estimation. framework, posterior probability of failure is calculated from the priors and test failure data.

Comparison of bracket debonding force between two conventional resin adhesives and a resin-reinforced glass ionomer cement: An in vitro and in vivo study

The purpose of this study was to compare the debonding force of orthodontic brackets bonded with two conventional resin adhesives (Resilience L3 and Light Bond) and a resin-reinforced glass ionomer cement (Fuji Ortho LC). For the in vitro part of the study, 80 extracted premolars were randomly divided into four groups. In groups A and B, brackets were bonded to unetched enamel using Fuji Ortho LC cement in wet and dry conditions, respectively. In groups C and D, brackets were bonded to etched enamel using Resilience L3 and Light Bond, respectively. Debonding force was determined using a servohydraulic testing machine at a crosshead speed of 1 mm/min. Data was analyzed using the ANOVA and Tukey-Kramer multiple comparison test at p<0.05. A significant difference was found in debonding force between unetched Fuji Ortho LC and the two conventional resins. There was no significant difference between the two conventional resins or between unetched resin-reinforced glass ionomer in the wet and dry conditions. For the in vivo part of the study, 30 patients were randomly assigned to one of the three bonding material groups. Bracket survival rates and distributions were obtained by following these patients for 1.2 years. Data was analyzed using the Kaplan-Meier product-limit estimates of survivorship function. Bond failure interface was determined using a modified adhesive remnant index (ARI). These results showed no significant difference between survival rates and distributions among the three bonding materials with respect to the type of malocclusion, type of orthodontic treatment, or location of bracket. There were significant differences between survival distributions of males and females in the unetched Fuji Ortho LC group and among type of teeth in the conventional resin groups. The predominant mode of bracket failure for the unetched Fuji Ortho LC cement was at the enamel-adhesive interface, and for conventional resins, the enamel-adhesive interface and the bracket-adhesive interface. These results suggest that resin-reinforced glass ionomer cement can withstand occlusal and orthodontic forces despite having a bond strength lower than that of conventional resin adhesives.

Development and Validation of a Literacy Assessment Tool for Persons With Diabetes

PURPOSE this research was conducted to develop a valid, reliable, quick, and nonstigmatizing tool for assessing literacy in the healthcare setting. METHODS The Literacy Assessment for Diabetes (LAD) instrument was developed as a word recognition test composed of 3 graded word lists in ascending difficulty. This literacy test, which was specific to diabetes, measured a patients ability to pronounce terms that they would encounter during clinic visits and in reading menu and self-care instructions. The majority of the terms were on a 4th-grade reading level, with the remaining words ranging from the 6th- through 16th-grade levels. To assess reliability and validity, the LAD was compared with the Wide Range Achievement Test (WRAT3) and the Rapid Estimate of Adult Literacy in Medicine (REALM) by administering all 3 tests to 203 participants in a test-retest study design. RESULTS All 3 tests (LAD, REALM, and WRAT3) reliably detected true intrasubject variation in word recognition from test to retest. In addition, LAD measured word recognition ability similar to the REALM and WRAT3. CONCLUSIONS The LAD is a reliable and valid instrument for measuring literacy in adults with diabetes. It can be administered in 3 minutes or less, and the raw score is scaled to a reading grade level.

Comparative Study of Clinical Evaluation of Heart Murmurs by General Pediatricians and Pediatric Cardiologists

In a study to compare the clinical diagnostic skills of academic general pediatricians and academic pediatric cardiologists in the evaluation of heart murmurs, a total of 128 patients (aged 1 month to 18 years) newly referred to a university pediatric cardiology clinic were evaluated by one of three general pediatricians and one of four pediatric cardiologists. The murmurs were clinically classified as innocent, pathologic, or possibly pathologic. The classification was revised after the review of electrocardiogram (EKG) and chest radiograph (CXR), if indicated. The definitive diagnosis was ascertained by echocardiography (94 normal, 34 abnormal). The general pediatricians identified as many pathologic heart murmurs as the pediatric cardiologists (27/34 vs. 29/34), with no difference in sensitivity, 79% vs. 85% (p=0.53). The similarity in sensitivity could be because the general pediatricians were more cautious in the classification of heart murmurs and had classified more innocent heart murmurs as pathologic than the pediatric cardiologists (13/39 vs. 3/23), 41% vs. 13% (p=0.02). The pediatric cardiologists correctly identified more innocent murmurs than general pediatricians (52/94 vs.72/94), with a better specificity, 55% vs. 76% (p=0.001); however, the accuracy of prediction of innocence was similar for both groups (52/59 vs. 72/77), 88% vs. 93% (p=0.36). The revision of diagnosis with review of EKG and CXR was more often misleading than helpful for either group. Academic general pediatricians would identify most of the pathologic murmurs and are no more likely than an academic pediatric cardiologist to misclassify a pathologic heart murmur as innocent. Clin Pediatr. 1999;38:511-518

Class III camouflage treatment: What are the limits?

INTRODUCTION The purpose of this study was to determine the skeletal, dental, and soft-tissue changes in response to camouflage Class III treatment. METHODS Thirty patients (average age, 12.4 + or - 1.0 years) with skeletal Class III malocclusions who completed comprehensive nonextraction orthodontic treatment were studied. Skeletal, dental, and soft-tissue changes were determined by using published cephalometric analyses. The quality of orthodontic treatment was standardized by registering the peer assessment rating index on the pretreatment and posttreatment study models. The change in the level of gingival attachment with treatment was determined on the study casts. The results were compared with a group of untreated subjects. Data were analyzed with repeated measures analysis and paired t tests. RESULTS The average change in the Wits appraisal was greater in the treated group (1.2 + or - 0.1 mm) than in the control group (-0.5 + or - 0.3 mm). The average peer assessment rating index score improved from 33.5 to 4.1. No significant differences were found for the level of gingival attachments between the treatment and control groups. The sagittal jaw relationship (ANB angle) did not improve with camouflage treatment. A wide range of tooth movements compensated for the skeletal changes in both groups. The upper and lower limits for incisal movement to compensate for Class III skeletal changes were 120 degrees to the sella-nasion line and 80 degrees to the mandibular plane, respectively. Greater increases in the angle of convexity were found in the treated group, indicating improved facial profiles. Greater increases in length of the upper lip were found in the treated group, corresponding to the changes in the hard tissues with treatment. CONCLUSIONS Significant dental and soft-tissue changes can be expected in young Class III patients treated with camouflage orthodontic tooth movement. A wide range of skeletal dysplasias can be camouflaged with tooth movement without deleterious effects to the periodontium. However, proper diagnosis and realistic treatment objectives are necessary to prevent undesirable sequelae.

Stability of Class II treatment with an edgewise crowned Herbst appliance in the early mixed dentition: Skeletal and dental changes.

INTRODUCTION The objectives of this research were to assess skeletal and dental changes in patients with Class II malocclusion treated with the edgewise crowned Herbst appliance in the early mixed dentition and to measure the stability of treatment after a second phase of fixed appliance therapy. METHODS Twenty-two patients (ages, 8.4 ± 1.0 years) with Class II Division 1 malocclusion treated consecutively with the edgewise crowned Herbst appliance in the early mixed dentition were studied. Lateral cephalograms were taken before Herbst treatment, immediately after Herbst treatment, and after a second phase of fixed appliance therapy. The results were compared with a control group of untreated Class II subjects selected from the Bolton-Brush study, matched by age, sex, and craniofacial morphology. A total of 37 sagittal, vertical, and angular cephalometric variables were evaluated. Changes in overjet and molar relationship were calculated. Changes due to growth were subtracted to obtain the net changes due to treatment. The data were analyzed by using analysis of variance (ANOVA) and the t tests. RESULTS Overcorrection with the Herbst appliance resulted in an average reduction in overjet of 7.0 mm and a change in molar relationship of 6.6 mm. Several factors contributed to the change in overjet: restraint of the forward movement of the maxilla (0.4 mm), forward movement of the mandible (2.0 mm), backward movement of the maxillary incisors (3.7 mm), and forward movement of the mandibular incisors (0.9 mm). Skeletal changes together with a 3.1-mm backward movement of the maxillary molars and a 1.1-mm forward movement of the mandibular molars contributed to the changes in molar relationship. After the second phase of fixed appliance therapy, the change in overjet was reduced to 2.8 mm. Most of the remaining overjet corrections were contributed by the restraint of maxillary growth (2.8 mm). The mandible moved posteriorly by 1.6 mm, and the mandibular incisors moved forward by 0.2 mm. Change in molar relationship was reduced to 2.2 mm. The maxillary molars moved backward by 0.2 mm, and the mandibular molars moved forward by 0.8 mm. CONCLUSIONS Overcorrection of Class II malocclusion with the edgewise crowned Herbst appliance in the early mixed dentition resulted in a significant reduction in overjet and correction of the molar relationship. A portion of the correction was maintained after a second phase of fixed appliance therapy because of the continuous restraint of maxillary growth and the dentoalveolar adaptations.

Tooth Whitening Effects on Bracket Bond Strength In Vivo

OBJECTIVE To test the hypothesis that there is no difference between the bracket survival rate of brackets bonded to bleached and unbleached teeth. MATERIALS AND METHODS Thirty-eight patients who required comprehensive orthodontic treatment were included in the study. A split mouth technique was used with one arch exposed to in-office whitening gel containing 38% hydrogen peroxide for 30 minutes, while the unbleached arch served as the control. Patients were divided into two groups: Brackets bonded within 24 hours after bleaching and brackets bonded 2-3 weeks after bleaching. The bracket survival rate was computed using the log-rank test (Kaplan-Meier Analysis). RESULTS A significantly higher rate of bracket failure was found with bleached teeth (16.6%) compared with unbleached teeth (1.8%) after 180 days. Brackets bonded within 24 hours of bleaching resulted in significantly higher clinical failure (14.5%) compared with those bonded after 3 weeks (2.1%). Adhesive Remnant Index scores of failed brackets revealed that the majority of failure in bleached teeth occurred in the enamel/resin interface. CONCLUSIONS The hypothesis was rejected. Brackets bonded within 24 hours after bleaching have a significantly higher risk for bond failure. Orthodontic bonding should be delayed for 2-3 weeks if patients have a history of in-office bleaching with 38% hydrogen peroxide.

Branded versus Generic Clozapine for Treatment of Schizophrenia

OBJECTIVE: To report clinical findings resulting from a switch from branded to generic clozapine. METHODS: Twenty patients diagnosed with schizophrenia were followed in this naturalistic outpatient study. The Positive and Negative Syndrome Scale (PANSS), Beck Anxiety Inventory (BAI), Abnormal Involuntary Movement Scale, and the Movement Disorder Assessment were used to assess differences in the clinical status of patients before and after switching from Clozaril to generic clozapine (Mylan Pharmaceuticals). Results were analyzed by means of the paired t-test and by calculation of the percent change in mean scores. A clinically significant change as measured by the PANSS was defined as a ± 20% change in mean scores at final evaluation. The design was open-label and non-blinded. RESULTS: At the final evaluation, the t-test revealed no significant differences between branded and generic clozapine for the total PA NSS, the positive symptom, negative symptom, and the general psychopathology subscales of the PANSS, and the BAI. There were no clinically significant changes for any measure. CONCLUSIONS: In this small group of patients with schizophrenia, no deterioration in clinical status in several domains was noted after changing from branded to generic clozapine. This finding is consistent with pharmacologic data suggesting bioequivalence of the 2 products. Results, however, must be interpreted cautiously due to the lack of optimal study controls and small sample size.

Medication Utilization Patterns and Methods of Suicidality in Borderline Personality Disorder

Background: Borderline personality disorder (BPD) is a psychiatric disorder characterized by suicidal thoughts/attempts and instability of mood, interpersonal relationships, and self-image. Patients with BPD engage in manipulative acts in apparent attempts to exert control in their interpersonal relationships. This issue of control may also be exhibited in their manner of self-medication. Objective: To examine the medication utilization patterns of patients with BPD versus patients without personality disorders in a control group and to compare methods of suicidality between the groups. Methods: A randomized, retrospective, chart review study was conducted at an academic medical center psychiatric hospital. The study examined the medication utilization patterns and methods of suicidality displayed over a one-year period for 29 patients hospitalized with BPD versus 29 patients in a control group. Results: The number of psychotropic, non-psychotropic, and total drugs on admission and discharge was significantly greater for patients with BPD compared with patients in the control group. There was no significant difference between the 2 groups with respect to overdose and cutting methods of suicidality. The mean number of Axis III discharge diagnoses in the control group upon discharge was significantly less than that in the study group. Approximately 25% of patients with BPD considered overdosage as a means to end their life. Conclusions: As patients with BPD receive more medications than patients without the disorder and often exhibit suicidal thoughts/attempts, clinicians should closely monitor the use of all medications.

Software reliability corroboration

We suggest that subjective reliability estimation from the development lifecycle, based on observed behavior or the reflection of ones belief in the system quality, be included in certification. In statistical terms, we hypothesize that a system failure occurs with the estimated probability. Presumed reliability needs to be corroborated by statistical testing during the reliability certification phase. As evidence relevant to the hypothesis increases, we change the degree of belief in the hypothesis. Depending on the corroboration evidence, the system is either certified or rejected. The advantage of the proposed theory is an economically acceptable number of required system certification tests, even for high assurance systems so far considered impossible to certify.