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Search Results: 1 - 10 of 31 matches for " Arschang Valipour "
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Clinical review: Humidifiers during non-invasive ventilation - key topics and practical implications
Antonio M Esquinas Rodriguez, Raffaele Scala, Arie Soroksky, Ahmed BaHammam, Alan de Klerk, Arschang Valipour, Davide Chiumello, Claude Martin, Anne E Holland
Critical Care , 2012, DOI: 10.1186/cc10534
Abstract: The human airway has an important role in heating and humidifying inspired gas, and recovering heat and moisture from expired gas. The amount of water vapor in a gas mixture can be measured as absolute humidity (AH) or relative humidity (RH) in relation to the temperature. AH is the total water present in the gas (mg H2O/L) and RH is the amount of water present expressed as the percentage of maximum carrying capacity at a given temperature [1]. The human airway must provide gas at core temperature and 100% RH at the alveolar surface in order to optimize gas exchange and protect lung tissue [2].Non-invasive ventilation (NIV) is a mechanical ventilation modality that does not utilize an invasive artificial airway (endotracheal tube or tracheostomy tube) [3]. NIV is usually delivered through a nasal or oro-nasal mask so the inspired gas passes through the upper airway where it is conditioned. Like during spontaneous breathing, patients under NIV require adequate humidification and heating of the inspired air (that is, gas conditioning) [3]. NIV delivers inspired air at high flow rates, which may overwhelm the usual airway humidification mechanisms. Inadequate gas conditioning has been associated with anatomical and functional deterioration of nasal mucosa (ciliary activity, mucus secretion, local blood flow, nasal resistance). In addition, there are also negative effects on tolerance to NIV when a patient breathes inadequately humidified air [1,3-5] (Table 1).Metaplastic changes and keratinization of the nasal epithelium and submucosa have been reported in patients on home-NIV when the level of humidification was inadequate for long periods [5]. These histopathological findings were confirmed by our recent survey, which found similar structural changes of the nasal mucosa in four patients with acute respiratory failure treated for 7 days with NIV without a humidification system added (unpublished data; Figure 1). This suggests that changes in the nasal mucosa occur rel
Sprinkle and Trickle Irrigation System Design Using Tapered Pipes for Pressure Loss Adjusting
Mohammad Valipour
Journal of Agricultural Science , 2012, DOI: 10.5539/jas.v4n12p125
Abstract: Accurate computing of amount of pressure loss is very important in sprinkle and trickle irrigation system design. Not correctly adjusted of pressure loss are causes lack of appropriate performance or failure of sprinkle and trickle irrigation system. By tapered pipes, pressure loss adjusted using increasing or decreasing of pressure head. In this study using HydroCalc software, ability of single and tapered pipes in pressure loss adjusting has been compared. Single and tapered laterals were able to adjusting of pressure loss but single manifolds were not able to achieving to the desired pressure head. In single lateral-tapered manifold system due to the lower pressure loss in laterals, can be use from several types of pipe diameters for manifolds but in tapered lateral-tapered manifold system due to the more pressure loss in laterals, the choice is limited. The best diameters for tapered manifolds with single lateral were 69.2-36.8 mm, 69.2-58.2-36.8 mm, and 58.2-46.0-36.8 mm whereas the best diameters for tapered manifold with tapered lateral were 69.2-46.0-36.8 mm.
Comparison of Surface Irrigation Simulation Models: Full Hydrodynamic, Zero Inertia, Kinematic Wave
Mohammad Valipour
Journal of Agricultural Science , 2012, DOI: 10.5539/jas.v4n12p68
Abstract: Some phenomena such as surface irrigation are so complex that it is very difficult to implement them in nature. For this purpose, simulation models are used. In this study, ability of full hydrodynamic, zero inertia, and kinematic wave models has been investigated in surface irrigation simulation. Using SIRMOD software, their performance has been compared. The results showed that full hydrodynamic and zero inertia models were very powerful in simulation process. For increasing of filed slope until amount of 0.01 full hydrodynamic and zero inertia models had not any difference but for more increasing of S0 due to the increasing of velocity, accuracy of zero inertia model dropped. In full hydrodynamic and zero inertia models for increase in Manning’s roughness coefficient amount of error was increased until n=0.15. After this amount, error remained constant thus n=0.15 determined as critical discharge. Accuracy of kinematic wave model reduced in clay and heavy clay soils, high discharges, high Manning’s roughness coefficient, and basin irrigation. However, in many situations all three models had the same answers and were capable tools to simulating of surface irrigation processes.
Channel Optimized Distributed Multiple Description Coding
Mehrdad Valipour,Farshad Lahouti
Mathematics , 2011, DOI: 10.1109/TSP.2011.2180903
Abstract: In this paper, channel optimized distributed multiple description vector quantization (CDMD) schemes are presented for distributed source coding in symmetric and asymmetric settings. The CDMD encoder is designed using a deterministic annealing approach over noisy channels with packet loss. A minimum mean squared error asymmetric CDMD decoder is proposed for effective reconstruction of a source, utilizing the side information (SI) and its corresponding received descriptions. The proposed iterative symmetric CDMD decoder jointly reconstructs the symbols of multiple correlated sources. Two types of symmetric CDMD decoders, namely the estimated-SI and the soft-SI decoders, are presented which respectively exploit the reconstructed symbols and a posteriori probabilities of other sources as SI in iterations. In a multiple source CDMD setting, for reconstruction of a source, three methods are proposed to select another source as its SI during the decoding. The methods operate based on minimum physical distance (in a wireless sensor network setting), maximum mutual information and minimum end-to-end distortion. The performance of the proposed systems and algorithms are evaluated and compared in detail.
Dividend Policy and Information Asymmetry from the Signaling Perspective
Reza Zare,Javad Moradi,Hashem Valipour
Asian Economic and Financial Review , 2013,
Abstract: This study attempts to examine the relevance of dividend policy and information asymmetry From the Signaling Perspective and Compare the relative information content of them. Based on sampling, 88 firms from Tehran Stock Exchange (TSE) were selected and examined during 2003 to 2010. The findings show that the profit division policy(Divisible profit proportion) has positive and significant relation with market data asymmetry namely when the profit division policy increases the data asymmetry increases, too. On the other side, the test findings indicate the investors are sensitive to the EPS changes and when the EPS changes are positive their divisible profit increases, but when the divisible profit of the company decreases the data boggles their mind and data asymmetry increases.
Asymmetric Information and Dividend Policy in Emerging Markets: Empirical Evidences from Iran
Hashem Valipour,Vahab Rostami,Mahdi Salehi
International Journal of Economics and Finance , 2009, DOI: 10.5539/ijef.v1n1p203
Abstract: Purpose-this study investigates the effect of asymmetric information on dividend policy in listed companies in Tehran Stock Exchange. Methodology-four main hypothesis have designed by theoretical framework, and tested on 111 listed companies in Tehran stock exchange during 2003 to 2007. The statistic analysis had done by malt- variable regression analysis. Findings-the study findings show that there is a meaningful and reverse relationship between asymmetric information and dividend policy. Some other findings show there is a meaningful relationship between dividend policy and return on stock but there is no meaningful relationship between dividend policy with firm size and book value to market value of equity ratio. Practical implementation-the finding of the study could be helpful for university students and users of financial information and other financial analysts in capital market.
Effects of Indole-3-butyric Acid on the Rooting Ability of Semi-hardwood Bougainvillea sp. Cuttings
Marzieh Babashpour Asl,Somayeh Shakueefar,Vida Valipour
Modern Applied Science , 2012, DOI: 10.5539/mas.v6n5p121
Abstract: The experiment was carried out to investigate the effect of different concentration of Indole-3-butyric acid (IBA) on the rooting ability of semi-hardwood Bougainvillea flower. The treatments were control (without IBA), 2000, 3000 and 4000 ppm IBA. The cuttings were treated with IBA solution for 7 seconds and immediately transferred to the rooting medium. Perlite was used as a rooting substrate. Treatment was evaluated in a completely randomized design (CRD) with 3 replications. According to the obtained results, there was no significant difference between IBA treatment and control on rooting percentage. The best effect of different levels of IBA on the number of root (8.67 roots per plant) was obtained at 2000 ppm IBA. The highest root length (151.42 mm) was observed at control and there was no significant difference between control and 2000, 4000 ppm IBA. It can be concluded that using perlite as a rooting substrate without using IBA (control) affected rooting ability in bougainvillea flower.
Asymmetric Information and the Role of Accounting in Emerging Markets Evidences from TSE
Javad Moradi,Hashem Valipour,Aida Dowran
Research Journal of Applied Sciences, Engineering and Technology , 2013,
Abstract: This study examines the value relevance (information content) of cash flow and accounting figures in situations where the information is asymmetrical and Compare the relative information content of them to clarify the role of accounting figures in investment decision making and mitigating the agency problems (specifically resulting from the existence of information asymmetry in the emerging markets). Based on testing a sample of 76 firms from Tehran Stock Exchange (TSE) during 2005 to 2011, the results support the priority of accounting figures over cash flows in the market (TSE). On the other hand, when the information is asymmetrical, the accounting figures are still more relevant than the cash flows and have more relative information content. At the same time, in small firms, the value relevance of the accounting figures compared to cash flows is more; while in large firms, the relative content of accounting figures and cash flow figures aren't significantly different.
Relationship between Working Capital, Operating Cash Flows and Operating Income: Empirical Evidences from Listed Firms in Tehran Stock Exchange
Hashem Valipour,Zakieh Shooshtarian,Esmail Ostovari
Asian Economic and Financial Review , 2012,
Abstract: The main purpose of this research is to investigate the relationship between working capital, operating cash flow and operating income, in the companies that listed in Tehran Stock Exchange. Panel analysis is applied to sample of 52 companies during the period 2000-2009. The results show that there is a positive relationship between working capital and operating profit. But there is not meaningful relationship between operating cash flows and working capital.
Sustainable Growth and Firm Risk from the Signaling Perspective
MOHEB ALI KANANI,Javad Moradi,Hashem Valipour
Asian Economic and Financial Review , 2013,
Abstract: This study attempts to examine the relevance of sustainable growth and its influence on firm’ financial and business risks and Compare the relative information content of them. Based on sampling, 85 firms from Tehran Stock Exchange (TSE) were selected and examined during 2003 to 2010. The Statistical tests findings showed that there is a significant relation between the firm’ real and sustainable growth difference and their financial risk, but there is no significant relation between the firm’ real and sustainable growths difference and their business risk.
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