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Search Results: 1 - 10 of 10909 matches for " Afshin Andreas "
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Theory of Carbon Nanotubes as Optical Nano Waveguides  [PDF]
Afshin Moradi
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2010, DOI: 10.4236/jemaa.2010.212088
Abstract: The propagation of surface plasmon waves in metallic single-walled carbon nanotubes is analyzed within the frame-work of the classical electrodynamics. The conduction electrons of the system are modelled by an in?nitesimally thin layer of free-electron gas which is described by means of the semiclassical kinetic theory of the electron dynamics. The effects of the energy band structure is taken into account and a more accurate dispersion relation for surface plasmon oscillations in the zig-zag and armchair nanotubes of metallic character is obtained.
Short-term effects of implemented high intensity shoulder elevation during computer work
Mette K Larsen, Afshin Samani, Pascal Madeleine, Henrik B Olsen, Karen S?gaard, Andreas Holtermann
BMC Musculoskeletal Disorders , 2009, DOI: 10.1186/1471-2474-10-101
Abstract: 18 female computer workers performed 2 sessions of 15 min standardized computer mouse work preceded by 1 min pause with and without prior high intensity contraction of shoulder elevation. RPE was reported, productivity (drawings per min) measured, and bipolar surface electromyography (EMG) recorded from the dominant upper trapezius during pauses and sessions of computer work. Repeated measure ANOVA with Bonferroni corrected post-hoc tests was applied for the statistical analyses.The main findings were that a high intensity shoulder elevation did not modify RPE, productivity or EMG activity of the upper trapezius during the subsequent pause and computer work. However, the high intensity contraction reduced the relative rest time of the uppermost (clavicular) trapezius part during the subsequent pause from computer work (p < 0.04).Since a preceding high intensity shoulder elevation did not impose a negative impact on perceived effort, productivity or upper trapezius activity during computer work, implementation of high intensity contraction during computer work to prevent neck-shoulder pain may be possible without affecting the working routines. However, the unexpected reduction in clavicular trapezius rest during a pause with preceding high intensity contraction requires further investigation before high intensity shoulder elevations can be recommended as an integrated part of computer work.The last decades, the fraction of the working population with primarily sedentary office work performing low load repetitive movement have escalated [1]. In the same period, increases in prevalence of neck-shoulder pain has occurred [2]. Correspondingly, one of the occupations with highest risk for neck-shoulder pain is computer workers [3], and extended computer work is generally considered a precursor for neck-shoulder pain often located in the upper part of the shoulder girdle [4-8]. The high prevalence of neck-shoulder pain in computer workers [3] is commonly considered to be
Reducing Broadband Shortwave Radiometer Calibration-Bias Caused by Longwave Irradiance in the Reference Direct Beam  [PDF]
Ibrahim Reda, Afshin Andreas, Mike Dooraghi, Manajit Sengupta, Aron Habte, Mark Kutchenreiter
Atmospheric and Climate Sciences (ACS) , 2017, DOI: 10.4236/acs.2017.71004
Abstract: Shortwave radiometers such as pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to consensus reference, maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window that measures the extended broadband spectrum of the terrestrial direct solar beam irradiance, unlike shortwave radiometers that cover a limited range of the spectrum. The difference between the two spectral ranges may lead to calibration bias that can exceed 1%. This article describes a method to reduce the calibration bias resulting from using broadband ACRs to calibrate shortwave radiometers by using an ACR with Schott glass window to measure the reference broadband shortwave irradiance in the terrestrial direct solar beam from 0.3 μm to 3 μm. Reducing the calibration bias will result in lowering the historical solar irradiance by at least 0.9%. The published results in this article might raise the awareness of the calibration discrepancy to the users of such radiometers, and open a discussion within the solar and atmospheric science community to define their expectation from such radiometers to the radiometers’ manufacturers and calibration providers.
Basal-like breast cancers: the phenotypic disparity between the cancer-initiating cells and tumor histology
Afshin Raouf
Breast Cancer Research , 2010, DOI: 10.1186/bcr2764
Abstract: In the mid -19th century, pathologists observed that some malignant tumors have features that are similar to those of the embryonic tissues (extensive proliferation and differentiation). This led pathologists to suggest that activation of quiescent, undifferentiated embryonic cells may be the root cause of cancer [1,2]. However, it was not until 1961 that Till and McCulloch [3] were able to provide the definitive proof that adult tissues are maintained by stem cells. Later, Bonnet and Dick [4] were able to show that, similarly to the normal adult tissues, malignant tumors can be initiated and maintained by a rare-cell population with stem cell properties (cancer stem cells). These observations suggest that a lack of knowledge about the unique biology of these cancer stem cells is the reason for the failure of the current cancer therapies. Moreover, they suggest that understanding the mechanisms that regulate the biology and function of the normal primitive cells will provide a framework to determine how alterations to these mechanisms can confer a cancer stem cell phenotype on these rare-cell populations.Recent research efforts have led to the isolation and molecular characterization of the normal human and mouse breast stem cells and progenitors [5-8]. These studies revealed that breast stem cells are estrogen receptor-negative (ER-) and therefore were thought to be the origin of the ER- basal-like breast tumors [9]. Currently, however, the nature of the cancer-initiating cells remains elusive. Cancer-initiating cells are referred to the normal cells in the adult tissues, including the stem cells and progenitors as well as the differentiated cells that can acquire enough mutations to transform into cancer stem cells. Therefore, cancer stem cells arise from cancer-initiating cells and are responsible for tumor recurrence (that is, proliferation and self-renewal potentials) and the tumor heterogeneity (that is, multi-lineage differentiation potential).To ascertain th
Comparison of Three Treatment Procedure of Retained Placenta: Manual Removal, Intrauterine Injection of Oxytetracycline and Concomitant Use of Both Methods in Dairy Cows
Afshin Davasaztabrizi
Research Journal of Biological Sciences , 2012, DOI: 10.3923/rjbsci.2011.682.685
Abstract: Retained placenta is defined as the failure to pass all or part of the placenta from the uterus within 24 h of calving. There are several potential causes for placental retention but the effects on the general health of the cow and her subsequent reproductive performance are costly events to the dairyman. In this study which carried out in Tabriz suburb, we used of 30 Holstein cows allocated in the 3 groups and treated as group 1; handling, group 2; oxytetracycline and group 3; concomitant use of method 1 and 2. Based on data revealed that there is a significant difference among group 2 with two other groups. Thus can be state that Method No. 2 is a good way to treatment of retained placenta. The negative effect of retained placentas on subsequent fertility is commonly due to delayed involution of the uterus and chronic endometritis, one of the more common causes of infertility. Some cows with retention are affected with permanent sterility due to pyometra, perimetritis, salpingitis (inflammation of oviducts), ovaritis or severe damage to the endometrium. In most animals, the major economic loss is due to slight to moderate loss of milk and impaired involution of the uterus, thus a delay in conception. Thus, retained placenta must be treated as soon as possible and based on the data oxytetracycline is appropriate method for treatment of this disorder.
Comparative Study of Pregnancy Rate of Dairy Cows Synchronized Through Select Synch with Estrous Synchronization by PGF
Afshin Davasaztabrizi
Research Journal of Biological Sciences , 2012, DOI: 10.3923/rjbsci.2012.1.3
Abstract: Historically, estrus synchronization has been promoted as a labor saving tool for those producers who want to capitalize on the superior genetics available through use of AI. However, the labor saving aspect is peanuts compared to the economic returns available when estrus synchronization is used as a reproductive management tool. The aim of this study was to comparison of the two different methods: select synch and estrous synchronization by PGF2α. In this study, about 68 newly parturited cows were examined about 25 days after their parturition for clean test. About 45 days after parturition cows were divided into 2 groups and prepared for artificial insemination. Animals of group 1 (36 cows) were inseminated by select Synch Method. Animals of group 2 were treated as estrus synchronization. Based on data obtained from Chi-square test, it has been revealed that there is no significant difference between two groups (p>0.05).
Survey of Vitamin A, β-Carotene, Calcium and Phosphorus Concentrations in Serum of Dairy Cows with Retained Placenta
Afshin Davasaztabrizi
Research Journal of Biological Sciences , 2012, DOI: 10.3923/rjbsci.2012.132.135
Abstract: Retained Placenta (RP) may result from a number of factors, such as abortion, forced labor, delayed gestation, early parturition, uterine atony, infections and seasonal and hormonal disorders. In addition, it is well known that deficiencies of some vitamins and minerals induce or predispose animals to RP. The objective of the present study was to investigate the between serum concentrations vitamin A, β-carotene, calcium and phosphorus and the development of RP in cows. The 25 cows were retained placenta; to wit they have not excreted their placenta after parturition. The 20 others have excreted their placenta normally after parturition. Blood samples were obtained from all understudying animals from tail vein by venoject. Samples were centrifuged and sera were prepared and amounts of vitamin A, β-carotene, calcium and phosphorus were measured. Data showed that there is no significant difference among vitamin A and β-carotene between two groups (p>0.05). While revealed that there is a significant difference in mean value of Ca and P among two groups.
Survey of Reasons of Culling in Dairy Holstein Herds in Tabriz Area of Iran
Afshin Davasaztabrizi
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2012.4246.4249
Abstract: To evaluate of the factors for culling of the Holstein dairy cows in an industrial herd in Tabriz, data of the reasons for deleting is divided in seven groups such as financial factors, infertility and reproduction problems, low milking cows, mastitis and udder problems, lameness, digestive system diseases, etc. At all, 2458 Holstein cows in 9 herds have evaluated. Selling the cow for the milk, infertility and low milking cows were the important reasons for culling that were 127 and 78 from 326 cows in order. The fourth reason for deleting was mastitis and udder problems that include 21 cows. The fifth factor was the digestive system diseases with 16 cows. The voluntary reason for culling was the selling cows plus low milking cows that was 56% of the culled cows. The most involuntary culling reason was for infertility and reproduction problems that were 24% of total and 41% of involuntary culling.
Estimation of P (Y
Afshin Ghanizadeh
Journal of Applied Sciences , 2011,
Abstract: In present study, we considered the problem of estimating R = P (Y Keywords maximum likelihood estimator --- moment estimator --- Monte-Carlo simulation --- mixture estimator --- outliers --- Newton-Raphson method --- Rayleigh distribution
Combined radiochemotherapy – the state of the art - part one
Afshin Radmard
European Journal of Oncology Pharmacy , 2007,
Abstract: The combination of chemotherapy and irradiation has improved outcome in many tumour entities especially when they are applied concurrently. Therapy results including overall survival rates for anal carcinoma, head and neck cancer and cervix carcinoma are presented.
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