A Study on anisotropy of cosmic ray distribution with a small array of water-cherenkov detectors

The study of the anisotropy of the arrival directions is an essential tool to investigate the origin and propagation of cosmic rays primaries. A simple way of recording many cosmic rays is to record coincidences between a number of detectors. We have monitored multi-TeV cosmic rays by a small array of water cherenkov detectors in Tehran(35 43 N, 51 20 E, 1200m a.s.l). More than 1.1*10^6 extensive air shower events were recorded. In addition to the Compton- Getting effect due to the motion of the earth in the Galaxy, an anisotropy has been observed which is due to a unidirectional anisotropy of cosmic ray flow along the Galactic arms.Comment: 16 pages 9 figs and one tabl

Impacts of nano-clay particles and heat-treating on out-of-phase thermo-mechanical fatigue characteristics in piston aluminum-silicon alloys

Abstract. In this article, the effect of nano-clay particles and heat-treating on thermo-mechanical fatigue (TMF) behaviors and failures of piston aluminum-silicon (AlSi) alloys was investigated. For this purpose, thermo-mechanical fatigue tests were conducted under out-of-phase (OP) loading conditions. Two loading conditions were checked based on different maximum temperatures (250, 300, and 350 °C) and various thermo-mechanical loading factors (100, 125, and 150%). The minimum temperature was constant in all tests at 50 °C under a heating/cooling rate of 10 °C/s and a dwell time of 5 s. Results showed that the nano-composites had a longer fatigue lifetime, at least 2 times higher, compared to the Al alloy, when the maximum temperature was 250 °C and the thermo-mechanical loading factor was 100%. However, no effective change was seen for the stress value and the plastic strain. At higher maximum temperatures, the change in the material behavior was lower. The fracture analysis by scanning electron microscopy (SEM) demonstrated that both materials had a brittle behavior due to cleavage and quasi-cleavage marks. The damage mechanism was also due to the Si-rich phase and intermetallics, respectively for the crack propagation and the micro-crack initiation

Impacts of nano-clay particles and heat-treating on out-of-phase thermo-mechanical fatigue characteristics in piston aluminum-silicon alloys

Abstract. In this article, the effect of nano-clay particles and heat-treating on thermo-mechanical fatigue (TMF) behaviors and failures of piston aluminum-silicon (AlSi) alloys was investigated. For this purpose, thermo-mechanical fatigue tests were conducted under out-of-phase (OP) loading conditions. Two loading conditions were checked based on different maximum temperatures (250, 300, and 350 °C) and various thermo-mechanical loading factors (100, 125, and 150%). The minimum temperature was constant in all tests at 50 °C under a heating/cooling rate of 10 °C/s and a dwell time of 5 s. Results showed that the nano-composites had a longer fatigue lifetime, at least 2 times higher, compared to the Al alloy, when the maximum temperature was 250 °C and the thermo-mechanical loading factor was 100%. However, no effective change was seen for the stress value and the plastic strain. At higher maximum temperatures, the change in the material behavior was lower. The fracture analysis by scanning electron microscopy (SEM) demonstrated that both materials had a brittle behavior due to cleavage and quasi-cleavage marks. The damage mechanism was also due to the Si-rich phase and intermetallics, respectively for the crack propagation and the micro-crack initiation

Supply and protected different population of Litopenaeus vannamei subadult zero foster (F0) from difference provinces Iran

Nowadays, Litopenaeus vannamei are the most important species of farmed penaeidae shrimp in the world that is rapidly replacing native species in areas aquaculture. Due to demand increase for this species culture, shrimp displacement to different areas may be associated with some potential pathogens transferred to new areas farmed. Therefore, in this study were prepared bi-osecurity conditions for specific disease-free production of L. vannamei. Thereafter, three populations (Molokaei, High health and mix of Molokaei and High health) of the shrimp various reserves were detected base on origin and genetic indexes such as: observed heterozygosity, expected heterozygosity, allele frequency, coefficient inbreeding, genetic differentiation, genetic distance and genetic identity. On the other hand, epidemiological studies indicate non pathogens (viral, bacterial, fungal and parasitic) recognition of different populations selected in the quarantine salon. The bioassay results showed that the average weight and length of the populations of High health and Mix significantly greater than was a population of Molokaei. The shrimp populations were stocked in fiberglass tank (five ton) and were kept separated in the quarantine salon. During maintenance shrimp of populations in the quarantine salon were evaluated living and non-living pathogens with PCR, microbiology and biochemical methods. There is not any pathogens detection from shrimp populations stocking in the quarantine salon, so the shrimps were carried over to pond for broodstock culture of specific pathogenic free

Predictive factors of early moderate/severe ovarian hyperstimulation syndrome in non-polycystic ovarian syndrome patients: a statistical model

Purpose: To evaluate demographic, medical history and clinical cycle characteristics of infertile non-polycystic ovary syndrome (NPCOS) women with the purpose of investigating their associations with the prevalence of moderate-to-severe OHSS. Methods: In this retrospective study, among 7073 in vitro fertilization and/or intracytoplasmic sperm injection (IVF/ICSI) cycles, 86 cases of NPCO patients who developed moderate-to-severe OHSS while being treated with IVF/ICSI cycles were analyzed during the period of January 2008 to December 2010 at Royan Institute. To review the OHSS risk factors, 172 NPCOS patients without developing OHSS, treated at the same period of time, were selected randomly by computer as control group. We used multiple logistic regression in a backward manner to build a prediction model. Results: The regression analysis revealed that the variables, including age odds ratio (OR) 0.9, confidence interval (CI) 0.81�0.99, antral follicles count (OR 4.3, CI 2.7�6.9), infertility cause (tubal factor, OR 11.5, CI 1.1�51.3), hypothyroidism (OR 3.8, CI 1.5�9.4) and positive history of ovarian surgery (OR 0.2, CI 0.05�0.9) were the most important predictors of OHSS. The regression model had an area under curve of 0.94, presenting an allowable discriminative performance that was equal with two strong predictive variables, including the number of follicles and serum estradiol level on human chorionic gonadotropin day. Conclusion(s): The predictive regression model based on primary characteristics of NPCOS patients had equal specificity in comparison with two mentioned strong predictive variables. Therefore, it may be beneficial to apply this model before the beginning of ovarian stimulation protocol. © 2015, Springer-Verlag Berlin Heidelberg

Instrumentation development for an array of water Cherenkov detectors for extensive air shower experiments

Abstract A new small array of Cherenkov detectors has been deployed in Tehran, 1200 m above sea level. This array contains four tanks of distilled water with a diameter of 64 cm and a height of 130 cm. The effective area of each tank is about 1382 cm 2 . They are used to detect air showers and to record the arrival time of the secondary particles. We have collected about 640 000 extensive air showers (EAS) in 8298 h of observation time from November 2006 to October 2007. The distribution of air showers in zenith and azimuth angles has been studied and a cos n θ distribution with n = 6.02 ± 0.01 was obtained for the zenith angle distribution. An asymmetry has been observed in the azimuthal distribution of EAS of cosmic rays due to geomagnetic field. The first and second amplitudes of the asymmetry are A I = 0.183 ± 0.001 and A II = 0.038 ± 0.001. Since the recent results are in good agreement with our previous results of scintillation detectors, and tanks of distilled water are cheaper, we prefer to use them instead of scintillators in a future larger array. By simulation, we have improved the size of the detectors to yield the highest efficiency. The best dimensions for each tank with a photomultiplier tube in the center of its lid are 40 cm in diameter and 60 cm in height

New Simple Method for Analysis of Extensive Air Showers

Cosmic rays have valuable information about universe surroundings us. Finding energy, mass and arrival direction of primary cosmic ray particle are the most important aspects of extensive air shower studies. In order to determine these parameters, arrival direction and core position of extensive air showers should be determined at first. In this article, a new method has been introduced that utilizes arrival time information of secondary particles of extensive air showers for finding their core location and correcting plane wave front approximation so that calculate the arrival direction of extensive air showers. This method does not need number sensitive detectors-detectors which are sensitive to the number of crossing particles- and consequently there is no need for lateral distribution models. This model has been developed by analysis of simulated events generated by CORSIKA package.Comment: published, and superseded by arXiv:1103.066