253 research outputs found
Inverse Prism based on Temporal Discontinuity and Spatial Dispersion
We introduce the concept of the inverse prism as the dual of the conventional
prism and deduce from this duality an implementation of it based on temporal
discontinuity and spatial dispersion provided by anisotropy. Moreover, we show
that this inverse prism exhibits the following three unique properties:
chromatic refraction birefringence, ordinary-monochromatic and extraordinary-
polychromatic temporal refraction, and linear-to-Lissajous polarization
transformation
Flexible-Resolution, Arbitrary-Input and Tunable Rotman Lens Spectrum Decomposer (RL-SD)
We present an enhanced design -- in terms of resolution flexibility, input
port position arbitrariness and frequency-range tunability -- of the planar
Rotman lens spectrum decomposer (RL-SD). This enhancement is achieved by
manipulating the output port locations through proper sampling of the
frequency-position law of the RL-SD, inserting a calibration array compensating
for frequency deviation induced by input modification and introducing port
switching, respectively. A complete design procedure is provided and two
enhanced RL-SD prototypes, with uniform port distribution and uniform frequency
resolution, respectively, are numerically and experimentally demonstrated
Analysis and Engineering of Light in Complex Media via Geometrical Optics
Ph.DDOCTOR OF PHILOSOPH
Assessment of demand for and utilization of dental services by insurance coverage in a developing oral health care system
Objectives This study aimed to evaluate the relationship between demand for and utilization of dental services by insurance coverage among adults in Iran.Methods A cross-sectional survey based on telephone interviews was done. A total of 6,029 adults participated in this study conducted in Iran. The interviews were carried out using a structured questionnaire and covered dental visits, demographics and socio-economic background.Results Of 6,029 participants, 86% reported having health insurance, 58% had public, and 28% had both public and commercial insurance. Those with both public and commercial insurance coverage had higher odds for dental visits within the past 12 months [odds ratio (OR) = 1.5], and for dental check-ups (OR = 1.5). Receipt of restorative and expensive services (OR = 1.4) was more likely by those with both public and commercial insurance. Tooth extraction was more likely in subjects with no insurance coverage (OR = 1.6).Conclusion This study revealed a positive relationship between insurance coverage and demand for and utilization of dental services in a country with a developing health care system
طب پیشگیری از دیدگاه حکیم جرجانی
Preventive medicine is a science which tries to maintain and increase the health in a population. Ancient Iranian scientists have played an important role in developing medical sciences, especially during middle ages. Jorjani was one of the greatest scientists which are known as the reviver of medical sciences. Treasure of Kharazmshah, the most popular book of Jorjani, is written in Persian. It is believed that there is no medical comprehensive book such as treasure in any country. A part of this book is devoted for preventive medicine. In traditional Persian medicine prevention is prior to treatment and there six principle necessities for preventing diseases named " Sette-ye-zarurieh " which consists of Air, Food and Water, Sleep and Wake, Movement and Stillness, Emotional states (Aaraz-e-nafsani), and Depletion and Retention (Estefragh and Ehteghan). Jorjani believed that prevention is easier and simpler that treatment.بهداشت عمومی یا پزشکی پیشگیری، شاخهای از علم پزشکی است که هدف آن حفظ و افزایش سطح سلامت افراد جامعه به صورت کلی است. دانشمندان ایرانی به ویژه در طی قرون وسطی که بر محافل علمی جهان، سیطره داشتند، نقش مهمی در پیشبرد دانش پزشکی ایفا کردهاند. جرجانی را یکی از دانشمندان بزرگ ایران و جهان در سدههای پنجم و ششم هجری و احیاکننده علم پزشکی میدانند. ذخیره خوارزمشاهی، معروفترین اثر جرجانی، به فارسی نوشته شده است. پیش از جرجانی، حتی بعد از او هم کتاب جامعی از این دست در هیچ کشوری نوشته نشده است. یکی از موضوعاتی که در طب سنتی ایران به آن پرداخته شده است، طب پیشگیری است. در طب سنتی ایران، پیشگیری از ابتلا به بیماری و حفظ سلامت افراد بر درمان تقدم دارد و بدین سبب اهمیت بسیاری دارد. مبحث سته ضروریه یا اصول ششگانه پیشگیری که در کتب حکمای طب سنتی ایران و از جمله در تألیفات جرجانی است، عبارتند از: هوا، حرکت و سکون، خواب و بیداری، خوردنی و آشامیدنی، استفراغ و احتقان و اعراض نفسانی. از دیدگاه جرجانی پیشگیری مقدم بر درمان بوده و سادهتر و کم هزینهتر است
Evaluating the Effect of Socio-Economic Status on DMFT Index in Children Aged 12 in Iran through Zero-Inflated Poisson Regression
Introduction: The most common index in dental studies is the decayed, missing, or filled teeth (dmft)/DMFT. Risk factor evaluation in order to investigate the significant factors that affect this DMFT in children has an important role in dental epidemiological studies. The aim of this study was to investigate the association between socioeconomic factors and dental caries.
Materials and Methods: This cross-sectional study was a part of a national survey for assessing the oral health status of Iranian citizens in 2012. The target population was children aged. The data and oral examination results were collected by the clinical examination form and trained calibrated dental group (dentists and hygienists). A zero-inflated Poisson regression model (ZIP) with a random effect was utilized for evaluating the effect of socioeconomic status on DMFT.
Results: In general, 1564 subjects were studied. From the entire subject in this study, the frequency of zero was 4176 (67%). The result of the ZIP model with random effect in zero part showed that socioeconomic status (OR = 1.97; P-value <0.001) had a significant effect on zero DMFT occurrences. The variance component of the random intercept in zero part was significant too (σ2 =17.11, P < 0.001).
Conclusion: The zero-inflated Poisson model with random effect in zero part was fitted to this data. Children from lower socioeconomic classes experienced more DMFT.
 
A Comparison of Emotional-Behavioral Problems of siblings at the Age Range of 3-9 Years Old of Children with Autism and Down syndrome
AbstractObjectives: Children's emotional-behavioral problems will have a huge impact on their future. It seems such problems are more seen in the siblings of children with special needs. The present study sought to compare emotional-behavioral problems in the healthy siblings of autistic children with the healthy siblings of children with Down syndrome in order to identify such children in Iran.Materials & Methods: This descriptive study was carried out on 174 healthy children aged between 3 and 9 years old among whom 58 cases had autistic siblings, 58 cases had siblings with Down syndrome, and 58 cases had typically development siblings. The participants were selected using convenience sampling technique. All volunteer parents filled in SDQ Questionnaire. The study results were calculated using independent sample t-test, two-way ANOVA, and Tukey post hoc test by SPSS Software V.21.Results: The mean overall score of Strengths and Difficulties questionnaire was reported as 17.98±6.19 in the autism group, 11.01±6.56 in the Down syndrome group and 4.43±4.34 in the healthy group so that there was a significant difference among autism, Down syndrome and healthy groups. In the group of siblings with Down syndrome, the problems were significantly more in the age range of 3 to 7 years old (p <0.05). However, no significant difference was observed in the scores of males and females (p> 0.05).Conclusions: Siblings with autism or Down syndrome can have especial psychological effects on healthy children in families in the way that such effect will be more with autistic children. Therefore, formulating beneficial strategies for their parents is useful to prevent emotional- behavioral problems.
A follow-up survey of graduates at Faculty of Paramedical Sciences of Shahid Beheshti Medical University (1997-2000) done to apply its results in educational planning and guidance of aptitudes
The Higher National Council of Medical Sciences Planning (HNCMSP) in Iran compile and approve educational programs by using expert academic staff, considering the country,s needs and studying the background of establishment of each major in other countries. Since the employment of graduates in occupations related to their majors is of utmost importance in educational planning, this survey has been done to investigate the graduates, employment and the factors affecting it, using a retrospective study.This survey is done on 120 graduates of Laboratory Sciences (LS), Medical Records (MR) and Radiology Technology (RT), at Paramedical Faculty of Shahid Beheshti Medical University (1997-2000).The subjects were randomly selected and given a questionnaire and the data was statistically analyzed using one-way ANOVA,Chi-Square, and Exact Fisher’s test (SPSS 15). 63.5 percent of the samples were females and the rest were males with an average age of 35.The coordination between their aptitude and major was highest (61%) in LS graduates, but lowest (21%) in MR graduates. Also the coordination between majors and interest was highest in LS graduates (48.4%).The results indicate that 6% of the subjects were post graduate students, 91% were employed and 9% were jobless.75% of them believed that their jobs were quite related to their majors and interest. They also mentioned the same factors for finding a suitable job (P=0.328).The results show that there is a direct relationship between the students, interest and aptitude on one hand, and their major and interest on the other. Moreover, because of the coordination between the majors and the country’s needs, the rate of unemployment has been found to be very low(9%).These findings can be helpful in reevaluation of educational planning, guidance of aptitudes towards the country’s economic priorities, and having a study of post graduation status.
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