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Effect of Composite or Ceramic Thickness on the Polymerization Hardness of 5 Different Dual-cured Resin Luting Cements

Objective: The aim of the present study was to evaluate the influence of ceramic and composite thickness on polymerization hardness of five different dual-cure resin cements. Materials and Methods: A total of 100 disc-shaped spacer, 10-mm in diameter and five varying thicknesses (1.0mm, 2.0mm, 3.0mm, 4.0mm, 5.0mm) were fabricated from ceramic and composite materials. Dual-cure resin cement specimens with 8-mm diameter were prepared using metal brass mold and activated by light beneath the composite and ceramic disc shaped spacers. A total of 100 specimens of five different dual-cure resins (RelyX, Variolink, NX3, Calibra, Panavia F2.0) were prepared. Knoop hardness of each dual-cure resin cement was measured at five different point using a microhardness device with a 500 gm load, after 1 hr, 1 day, and 1 week polymerization. All data were statistically evaluated using one-way ANOVA. Results: Multivariate analysis of variance revealed significant differences in hardness of specimens dual-cured under composite resin or ceramic spacers and different time intervals (P<.001). Specimens cured through composite resin spacers showed less hardness values than ceramic spacers, with increasing thickness of the spacer. Also increasing the thickness of the composite or ceramic spacers produced a statistically significant decrease in microhardness of the dual-cure cements (P<.05). Conclusions: Hardness values significantly reduced when composite spacers were thicker than 2 mm and ceramic spacers thicker than 3 mm. Dual-cured resin cements are needed to be improved to achieve sufficient degree of hardening under composite and ceramic restorations. Different commercially available brands have different polymerization properties

Custom-made Gold Implant for Management of Lagophthalmos: A Case Report

Lagophthalmos is defined as the inability to close the eyelids completely. This situation may lead to corneal problems such as epithelial defects, stromal thinning, exposure keratitis, bacterial infection, perforation, and blindness. A patient with lagophthalmos underwent insertion of a custom-made gold weight implant. After implantation, the patient was able to close her eye and expressed high cosmetic and aesthetic results. Fabrication of gold weight implant by the means of a rolling machine is an effective and easy way and should be considered in the management of lagophthalmos

3D Printed Subject Models for Measurement of Head-related Transfer Function (HRTF)

This disclosure describes techniques to determine individual head-related transfer functions (HRTFs) using a large number of three-dimensional (3D) printed human subject models. Per techniques of this disclosure, 3D printing technology is utilized to generate multiple head model structures, ear model structure, and neck and torso structures of different sizes and shapes to mimic heads and ears observed in human subjects. The head models and ear models are combined in different ways with different neck and torso structures and accessories to create hundreds to thousands customized subject models. The created subject models are used to measure HRTFs. In some examples, the heads and pinnae are directly printed in soft silicone rubber by utilizing specialized 3D printers that can precisely create models that accurately mimic how sound reflects off human skin. In other examples, a female mold casting shell is first 3D printed, which can be filled with materials of varying shore hardness. The use of 3D printed components that can be combined to generate a large number of subject models enables accurate measurement of a large number of high-quality HRTFs at scale without requiring human subjects

Wearable Knee Health Rehabilitation Assessment using Acoustical Emissions

Each year, approximately 200,000 Americans endure anterior cruciate ligament (ACL) tears, and 100,000 reconstructive procedures are conducted to repair the injured knees (1). The injury itself, and the long rehabilitation process that follows, can majorly disrupt the quality of life for these Americans through missed workdays, reduction of overall physical activity, and increased risk of re-injury in future activities. Wearable technologies for quantifying the state of rehabilitation, and providing feedback to the user regarding which activities or intensities of activities are safe to perform at any given time, could potentially help accelerate the rehabilitation process as well as reduce the risk of re-injury. Our lab has developed a novel, wearable sensing system based on miniature piezoelectric contact microphones for measuring the acoustical emissions from the knee during movements such as unloaded flexion / extension, sit-to-stand, and walking activities. The system consists of two Knowles BU-23173 contact microphones (Knowles, Itasca, IL) positioned on the medial and lateral sides of the patella, connected to custom, analog pre-amplifier circuits and a microcontroller for digitization and data storage on a secure digital (SD) card. In addition to the acoustical sensing, the system includes two integrated inertial measurement sensors including accelerometer and gyroscope modalities to enable joint angle calculations; these sensors, with digital outputs, are connected directly to the same microcontroller via serial peripheral interface (SPI). The system provides low noise, accurate joint acoustical emission and angle measurements in a wearable form factor, and has several hours of battery life. We have also taken measurements from healthy subjects, and athletes following acute ACL tear, to determine initial features from these acoustical emissions that are associated with injured versus healthy joints. We have found that the main acoustic clicks during particular motions occurred at consistent joint angles for healthy subjects based on intraclass correlation coefficient analysis (ICC(1,1) = 0.94 and ICC(1,k) = 0.99) (2). For one subject with an ACL tear, we found that the consistency of the joint acoustical emissions was lower for the injured knee as compared to the healthy knee in the recording immediately following the injury (\u3c 7 days), and improved following six months of rehabilitation. We envision using the wearable system we have recently completed to conduct further experiments with subjects following acute ACL tears, and tracking the progress of the rehabilitation while simultaneously measuring acoustical emissions in the context of particular movements. This data will then serve as a foundation for creating subject-specific algorithms for assessing rehabilitation and providing feedback to the users

Linear dimensional change, compressive strength and detail reproduction in type IV dental stone dried at room temperature and in a microwave oven

The type IV dental stone is widely used for the fabrication of dyes and master casts for fixed and removable partial prostheses. It is typically normal to wait at least 24 hours for the casts to dry prior to beginning the laboratory procedures. The waiting time has been shown to be greatly reduced by using microwave drying. OBJECTIVE: This study evaluated the influence of drying techniques at room temperature and microwave oven on the linear dimensional change, compressive strength and detail reproduction in type IV dental stones. MATERIAL AND METHODS: Three type IV dental stone brands were selected; Elite Rock, Shera Premium and Durone IV. Two different drying protocols were tested in 4 groups (n=10); G1 - room temperature (25±4ºC) dried for 2 hours; G2 - room temperature dried for 24 hours; G3 - room temperature dried for 7 days and G4 - microwave oven dried at 800 W for 5 minutes and after 2 hours at room temperature. After drying, the samples were assayed for dimensional charges. The sample surface was submitted to the ImageTool 3.0 software for compressive strength in a universal testing machine with a cell load of 50 KN at a crosshead speed of 0.5 mm/minutes and the detail reproduction was analyzed with a stereomicroscope at 25x magnification. The statistical analysis of the linear dimensional change and compressive strength data were conducted by the ANOVA test followed by the Tukey test (p<0.05). Detailed reproduction values were reported in percentages. RESULTS: For the compressive strength test, Elite Rock and Durone IV did not present significant differences between G2 and G4, while Shera Premium did not present differences between G3 and G4. The best reproduction levels were observed for G3. CONCLUSIONS: Dental stone microwave oven drying showed a linear dimensional change similar to after room temperature drying for 24 hours and 7 days. The compressive strength of the stone dried in the microwave oven was similar to those dried at room temperature for 24 hours, with the exception of Shera Premium, which had similar results for microwave and room temperature drying for 7 days. For the microwave drying method the detail reproduction levels for samples dried at room temperature for 24 hours and 7 days were similar, except for the Durone IV

The ontogeny of antipredator behavior: age differences in California ground squirrels (Otospermophilus beecheyi) at multiple stages of rattlesnake encounters

Newborn offspring of animals often exhibit fully functional innate antipredator behaviors, but they may also require learning or further development to acquire appropriate responses. Experience allows offspring to modify responses to specific threats and also leaves them vulnerable during the learning period. However, antipredator behaviors used at one stage of a predator encounter may compensate for deficiencies at another stage, a phenomenon that may reduce the overall risk of young that are vulnerable at one or more stages. Few studies have examined age differences in the effectiveness of antipredator behaviors across multiple stages of a predator encounter. In this study, we examined age differences in the antipredator behaviors of California ground squirrels (Otospermophilus beecheyi) during the detection, interaction, and attack stages of Pacific rattlesnake (Crotalus oreganus) encounters. Using free-ranging squirrels, we examined the ability to detect free-ranging rattlesnakes, snake-directed behaviors after discovery of a snake, and responses to simulated rattlesnake strikes. We found that age was the most important factor in snake detection, with adults being more likely to detect snakes than pups. We also found that adults performed more tail flagging (a predator-deterrent signal) toward snakes and were more likely to investigate a snake’s refuge when interacting with a hidden snake. In field experiments simulating snake strikes, adults exhibited faster reaction times than pups. Our results show that snake detection improves with age and that pups probably avoid rattlesnakes and minimize time spent in close proximity to them to compensate for their reduced reaction times to strikes

A Turkish Construction Company’s Project Management Plan Guide Before Commencement Of The Project In Azerbaijan

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2008Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2008Bu çalışmada, Azerbaycan’da taahhüt işi gerçekleştirecek bir Türk Müteahhit firma açısından, yapım aşaması öncesi, ülke verileri değerlendirilmiş, proje yönetim planı çalışmaları hazırlanmıştır. Azerbaycan’ ın kısaca ülke tanıtımı yapılmış, ülkenin ekonomik gelişimi istatistiksel verilerle ortaya konmuştur. Ülkenin vergi kanunları, iş kanunları, yabancı işçi çalıştırma kanunları ve gümrük mevzuatları 2008 yılı kanun değişiklikleri ile beraber incelenmiştir. Azerbaycan’ın Türkiye ile ilişkileri, ilişkilerin gelişimi, ortak yönler açıklanmış, ekonomik ilişkiler sayısal verilerle belirtilmiştir. Ülkede inşaat sektörünün konumu, malzeme olanakları ve yapılan projeler anlatılmış, ülke sektörünün güçlü-zayıf yönleri, fırsat-tehditleri SWOT analizi ile değerlendirilmiştir. PMI proje yönetim sistemi incelenerek Türk Müteahhit firmanın Azerbaycan’da yapım aşamasında inşaat proje yönetimine rehberlik edecek; bütçe&finansman yönetim planı, süre yönetim planı, insan kaynakları yönetim planı, kalite yönetim planı, sözleşme yönetim planı ve iş güvenliği yönetim planı çalışmaları, yerel ülke şartları da değerlendirilerek hazırlanmıştır. Proje yönetim planına ek olarak; altyüklenici tip sözleşmesinin ana başlıklarının Türkçe-Azerice karşılıklıları, Azericenin Türkçeye yakınlığını belirtmek amacıyla hazırlanmıştır. FIDIC inşaat işleri şartnamesi uyarınca, ülke şartlarında, yüklenici, kontrollük ve işveren arasında sorumluluk ve risk paylaşımı değerlendirilmesi hazırlanmıştır. Ülke şartlarında müteahhit firmanın maliyet yönetiminin temelini oluşturacak yazılım sistemi hazırlık çalışmaları kapsamında proje organizasyonu birimlerinin program üzerindeki görev ve sorumlulukları açıklanmıştır.In this study, Azerbaijan’s Country datas are searched and project managent plan is prepared for a Turkish Construction Company before commencement of construction works, A brief presentation of Azerbaijan is given and country’s economical improvement is declared by statistics. Country’s tax laws, social work laws, work laws for foreigners, custom laws and rules are summarized with the regulations in 2008. The improvement of the relations and the similarities between Turkey and Azerbaijan are explained and the economical relations are clarified by statistics. Moreover, the construction projects which have been completed are expressed and construction material resources, procurement alternatives are stated. The construction sector strengths-weakness oppurtunities-threats are analyzed by SWOT method. Moreover, accordindg to PMI project management system, budget&finance management plan, time management plan, human resource management plan, quality management plan, contract&risk management plan, health and safety management plans are prepared. These plans will guide the Turkish Construction Company preparing the construction project plan in Azerbaijan. In addition to main parts, a simple subcontractor contract topics in Azerbaijan and Turkish languages are listed. Moreover, according to FIDIC clauses, the responsibility and risk sharing between Client, Engineer and Contractor is prepared for Azerbaijan conditions. In order to prepare cost management software, the duties and responsibilities of the program users are listed and attached.Yüksek LisansM.Sc