We present an experimental and theoretical investigation of spontaneous pattern formation in the transverse section of a single retroreflected laser beam passing through a cloud of cold rubidium atoms. In contrast to previously investigated systems, the nonlinearity at work here is that of a two-level atom, which realizes the paradigmatic situation considered in many theoretical studies of opti...

background : hepatitis b virus (hbv) and hepatitis c virus (hcv) infections are major global public health problems. this study was conducted to investigate the incidence rate of these infections over six successive years in hamadan province, the west of iran. methods: this retrospective cohort study was conducted on the database of hepatitis registry. in this study, 1257 subjects infected by h...

1. introduction as strongly accepted among climatologists, climate change is a result of human activities. there is disagreement about how to define climate change, because of tremendous difference of climate changes in scale, intensity and occurrence time in various regions. recently there have been several observation analyses involving daily and extreme daily temperature trend and variabilit...

introduction no2 is not only a potential air pollutant in urban and industrial environments but also a precursor for smog of urban environment that is another ozone pollutant as well. some of the urban environments in iran have high tropospheric and near surface no2 which requires research attentions especially in these years. that is the issue of concern in the present study using satellite da...

this study was conducted during 2003-2004 and 2004-2005 growing seasons at shirvan ‎agricultural research station, to evaluate the performance of eight winter chickpea seed lines. ‎the experiment conducted in randomized complete block design with four replications. during ‎the growing season, date of flowering, plant height, number of pod per plant, number of seed ‎per pod and date of maturity ...

  Background: This study attempted to investigate traffic accident fatalities during 2004-2009 and the effect of fuel rationing on traffic accident fatalities .   Materials and Methods: This was a cross-sectional study on available data of all traffic accident fatalities in Fars Province, Iran, during 2004-2009. To identify and fit the best model, various instruments, including the...