Hollow core photonic bandgap fibers provide a new geometry for the realization and enhancement of many nonlinear optical effects. Such fibers offer novel guidance and dispersion properties that provide an advantage over conventional fibers for various applications. Dispersion, which expresses the variation with wavelength of the guided-mode group velocity, is one of the most important properties of optical fibers. Photonic crystal fibers (PCFs) offer much larger flexibility than conventional fibers with respect to tailoring of the dispersion curve. This is partly due to the large refractive-index contrast available in the silica/air microstructures, and partly due to the possibility of making complex refractive-index structure over the fiber cross section. In this paper the fundamental physical mechanism has been discussed determining the dispersion properties of PCFs, and the dispersion in a gas filled hollow core photonic crystal fiber has been calculated. We calculate the dispersion of air filled hollow core photonic crystal fiber, also calculate the dispersion of N2 gas filled hollow core photonic crystal fiber and finally we calculate the dispersion of He gas filled hollow core photonic crystal fiber.
Aim: The Aim of the study is to compare between Er,Cr:YSGG 2780 nm laser and carbide fissure bur in root-end resection regarding the morphological variations, temperature changes and the duration of resection process.
Settings and Design: 5 W, 25 Hz, 50% water, 80% air,25.47 J/cm2 .
Material and method: twenty-one extracted single rooted teeth endodontically were treated, twenty teeth were obturated and divided into two groups according to method of resection. Group 1 root-end resected using cross cut carbide bur while group 2 root-end resected using laser with MGG6 sapphire tip of 600 μm diameter. Temperature on external root surface and duration of resection were recor
... Show MoreHerbal remedies are used in induction of lactation. In view of that .Borage Officinalis was employed to ensure an abundant milk supply or rectify milk insufficiency .However, this remedy has not been scientifically tested .The animals were treated with the aqueous extract of Borage Officinalis flowers at a daily concentration of 100 mg / kg body weight /ml for each rat through Oro-gastric tube for 14 days. Animals were subdivided into subgroups according to their physiological status. Mammary glands of these animals were processed for histological, histochemical and immunohistochemical studies. Parameters indicated that the aqueous extract of Borage Officinalis flowers induced lactogenesis in the mammmary glands of virgin and pregnant rats
... Show MoreHuman herpes virus-8 (HHV-8) infection has increased recently in Arabic countries. HHV-8 in healthy persons does not necessarily cause life-threatening infection, and however, it causes a more severe infection among immunocompromised patients. The distribution of HHV-8 genotypes varies according to ethnicity and depends on the geographic region prior rapid development of global travel. A cross sectional prospective study included a hundred healthy blood donor samples with a mean age of (36.60±10.381), 81% were positive for molecular detection of HHV-8 DNA. PCR results for HHV-8 were strongly related with risk factors such as the number of sexual relations, previous surgeries, blood transfusion, dental operation, and the number of b
... Show MoreLearning the vocabulary of a language has great impact on acquiring that language. Many scholars in the field of language learning emphasize the importance of vocabulary as part of the learner's communicative competence, considering it the heart of language. One of the best methods of learning vocabulary is to focus on those words of high frequency. The present article is a corpus based approach to the study of vocabulary whereby the research data are analyzed quantitatively using the software program "AntWordprofiler". This program analyses new input research data in terms of already stored reliable corpora. The aim of this article is to find out whether the vocabularies used in the English textbook for Intermediate Schools in Iraq are con
... Show Moreالخلاصة
يجمع المختصون أن ليس من نقد إلا وكان مُرحِّلا لنظرية لسانية إلى فضائه، فكان أثر اللسانيات السوسيرية، ومن ثم اللسانيات التوليدية التحويلية معروفا، ولم يكن هذا الأثر محدودا باللسانيين أو نقاد الأدب فحسب، بل امتد إلى الشعراء والجماليين أيضا. وفي هذا البحث سنتوقف عند أثر اللسانيات الوظيفية، وهو ما لم يتوقف عنده إلا قلة من المختصين. ولن نقف عند نقد الوظيفيين للشعر، بل سنقف عند نقدهم للرواية، بقراءة
... Show MoreThis study examined the imperative construction: the command, the interrogative, the prohibition, the call, and the wish. In the Diwan of Al-Shamakh bin Dirar; where the poetic verses were monitored in each of the topics of the student's creation, and the rhetorical meanings that he came out with. What is new in this study is that it is the first to study the demanded composition in the poetry of a glorious poet, Al-Shammakh bin Dirar Al-Dhubyani. As his poetry did not receive such a study, it sought to employ what was written by rhetoric scholars, in an attempt to explore the demanded composition in the poetry of Al-Shamakh. The study adopted the descriptive analytical approach, which is based on counting the number of times the poet us
... Show MoreThis research is an attempt to study aspects of syntactic deviation in AbdulWahhab Al-Bayyati with reference to English. It reviews this phenomenon from an extra-linguistic viewpoint. It adopts a functional approach depending on the stipulates of systemic Functional Grammar as developed by M.A.K. Halliday and others adopting this approach. Within related perspective, fairly’s taxonomy (1975) has been chosen to analyze the types of syntactic deviation because it has been found suitable and relevant to describe this phenomenon. The research hypothesizes that syntactic deviation is pervasive in Arabic poetry, in general and in Abdul-Wahhab Al-Bayyati Poetry in specific, and can be analyzed in the light of systemic Functional Grammar
... Show MoreThe Dynamic Load Factor (DLF) is defined as the ratio between the maximum dynamic and static responses in terms of stress, strain, deflection, reaction, etc. DLF adopted by different design codes is based on parameters such as bridge span length, traffic load models, and bridge natural frequency. During the last decades, a lot of researches have been made to study the DLF of simply supported bridges due to vehicle loading. On the other hand, fewer works have been reported on continuous bridges especially with skew supports. This paper focuses on the investigation of the DLF for a highly skewed steel I-girder bridge, namely the US13 Bridge in Delaware State, USA. Field testing under various load passes of a weighed load vehicle was u
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