The aim of this study was to compare the proportion of financial leverage in companies before and after the use of off-balance sheet financing in firms listed in the Tehran Stock Exchange. The research method was causal-comparative descriptive. The population was all the accepted companies in Tehran Stock Exchange (cars and car fragments, petrochemicals, petroleum products, cement, pharmaceutical, home and sugar appliances) between years of 2010 and 2014 that 87 companies were selected at random. Data were analyzed using independent t-test. Results showed that the average financial leverage for companies which have used off-balance sheet financing was equal to 0.6398 and the average financial leverage for companies that did not use off-balance sheet financing has been equal to 0.5612. Therefore, there was no significant difference between averages of the two samples. Other results showed that the average of return on investment (ROI) ratio in companies that used off-balance sheet financing had no significant statistical reference with an average of return on investment (ROI) ratio in companies that did not use off-balance sheet financing. As well, the average of return on owner's equity (ROE) ratio in companies that have used off-balance sheet financing had no significant statistical difference with the average of return on owner's equity (ROE) ratio in companies that have not used off-balance sheet financing.

There is a compelling need for apportionment of pollutants' sources to facilitate their reduction through proper management plans. The present study was designed to determine the contribution of each possible source of total suspended particles in Ahvaz's ambient air using positive matrix factorization (PMF), chemical mass balance (CMB), and the SPECIATE database. The sampling program undertaken followed EPA's guidelines and finally resulted in 74 samples. The concentration of 33 elemental and 10 ionic species were measured during a whole year. Three modeling approaches were applied: PMF, the integrated use of PMF and CMB, and the integrated use of the SPECIATE database and CMB. Six sources were derived by PMF: crustal dust (30.6%), industrial and mining activities (25.4%), motor vehicles (23.4%), marine aerosols (11.5%), secondary inorganic aerosols (5.7%), and road dust (3.4%). The contributions of sources from PMF-CMB approach were crustal dust (32.9%), industrial and mining activities (20.9%), motor vehicles (19.7%), marine aerosols (11.1%), secondary inorganic aerosols (9.2%), and road dust (9.36%). Seven sources were derived by SPECIATE-CMB approach: crustal dust (23.2%), industrial and mining activities (20.1%), motor vehicles (17.5%), marine aerosols (12.4%), secondary inorganic aerosols (4.8%), road dust (5.3%), and "nondetermined sources" factor (16.7%). Despite the different contributions of sources, there is a noticeable consistency between the results of these approaches. Furthermore, because of the approved performance of combined receptor models in previous studies and the presence of sufficient data on the number of species and samples, the results of the PMF-CMB approach are possibly the most realistic among those of the three applied approaches.

No abstract

The process of electron acceleration by both Bessel-Gaussian (BG) and Gaussian (G) laser pulses has been investigated comparatively in a homogeneous plasma. Starting with the hydrodynamics fluid and the Maxwell's equations, the three corresponding equations could be acquired which allow us to evaluate electron density perturbations (n ′ e ), wakefield (E w ) and electron energy-gain (ΔW) respectively for both pulses. Here, the pulse duration and the electron plasma period are taken the same, and by utilizing the perturbation theory the proposed equations have been solved. The analytical results show that the wakefield which leads to electron acceleration, depends on pulse intensity (I), pulse length (L), pulse wavelength ( ) and plasma density (n). Furthermore, by comparing the outcomes, the BG pulse is found to be most suitable for wakefield excitation. The pertinent electron could be accelerated up to 90 MeV if I = 4 × 10 21 W/m 2 , L = 20 μm and n = 5.318 × 10 24 m −3 . Our results are in a good agreement with experimental data reported in literature.

Recently, nonthermal atmospheric pressure plasma has been used in medical devices for sterilization, blood coagulation, induction of apoptosis in cancer cells, etc. The purpose of this study is to evaluate the impact of cold atmospheric plasma on coagulation time in patients under treatment with warfarin as an anticoagulant agent (group A) and to compare this impact in healthy persons (group B). To measure the coagulation time, Clotting Time (CT) is used. After obtaining informed consent from each subject, two venous blood samples are taken to check CT. One sample is processed with plasma (case sample) and the other sample is not processed with plasma. CT in both samples is measured by a physician and recorded in a form in addition to demographic characteristics and drug history. The data are analysed using Statistical Package for the Social Sciences (SPSS) software. The Mann-Whitney test is used for comparison between groups and the Wilcoxon signed-ranks test is used to compare the difference between CT before and after plasma processing. The results show the significant effect of plasma on the reduction of plasma coagulation time, and this reduction is higher in the warfarin-treated group.