197 research outputs found
The Calculation of Continuity and Intensity of Droughts using Modified SPEI Index (Case study: Tabriz and Urmia Cities)
No full textThe Calculation of Continuity and Intensity of Droughts using Modified SPEI Index (Case study: Tabriz and Urmia Cities) Marhamat Sebghati*1, Hesam Ahmadi2 and Alireza Moghaddam3 1M.Sc. Faculty of Natural Resources (Watershed Managment), Urmia University, Urmia, Iran 2Assistance Prof. Faculty of Natural Resources (Watershed Managment ), Urmia University, Urmia, Iran 3PhD Candidate of Water Resources Engineering, Urmia University, Urmia, Iran *Corresponding Author: [email protected] Abstract In recent years, global climate change and increasing drought are the important environmental issues, and many studies have been done about these issues. In this research, continuity and intensity of drought for Tabriz and Urmia cities, during 31 years period, using corrected SPEI index by Penman-Monteith FAO method was investigated. Mmoving average of 3, 6 and 12 month for monitoring rainfall trend was used comparison. The results showed that SPEI index in both cities were mainly faced with drought conditions. In addition, analysis of the moving average, drought index and statistical distributions of wet and dry years showed same results in most years for both citis. The most intensive drought index derived for Tabriz and Urmia stations were equal to -2.75 and -2 respectively. The longest drought indicated for both cities was within 2005 to 2010. Keywords: Statistical distributions, drought, SPEI Index, moving average, Penman-Monteith FAO
Comparison of Efficacy and Complication of Alteplase Injection in Acute Ischemic Stroke
No full textBackground and Aim: Alteplase is a thrombolytic drug that is produced by recombinant DNA technology. Tissue plasminogen activator enzyme which converts plasminogen to the active form of plasmin is also produced by the same technology; it causes fibrinolysis and clot dissolution. This study aimed to compare the efficacy and complications of Alteplase injection in patients with acute ischemic stroke (AIS( during the first 3 hours and 3-4.5 hours after the onset of symptoms.
Methods: In this study, patients with AIS who were referred to Golestan Hospital of Ahvaz city during 2018-2019 were selected. Information was collected by a checklist.
Results: The results showed that the mean Modified Rankin Scale (mRS) for 3 months and 6 months (p-value: 0.91 for 3 months and p-value: 0.80 for 6 months) and National Institutes of Health Stroke Scale (NIHSS) (p-value: 0.21) were not significantly different between both groups; statistically, no significant relationship was observed between them. The incidence of complications after treatment was almost similar, in both groups.
Conclusion: Finally, it was concluded that complications and efficacy of rt-PA (Alteplase) injection were not statistically different, between the two groups under study.
*Corresponding Author: Gholamreza Shamsaei; Email: [email protected]; [email protected]
Please cite this article as: Amirazodi E, Shamsaei G, Rafie S, Kashipazha D, Hesam S. Comparison of Efficacy and Complication of Alteplase Injection in Acute Ischemic Stroke. Arch Med Lab Sci. 2021;7:1-6 (e4). https://doi.org/10.22037/amls.v7.3350
Faster than the Speed of Life: Accelerating Developmental Biology Simulations with GPUs and FPGAs
No full textLife scientists are faced with the tough challenge of developing high-performance computer simulations of their increasingly complex models. BioDynaMo is an open-source biological simulation platform that aims to alleviate them from the intricacies that go into development. Life scientists are able to base their models on top of BioDynaMo’s highly optimized core execution engine. At the core of all biological simulations is the mechanical interactions between possibly millions of objects. In this work we investigate the currently implemented method of handling mechanical interactions, and ways to improve the performance in order to enable large-scale and complex simulations. We propose to replace the existing kd-tree implementation for neighborhood operations with a uniform grid method that allows us to take advantage of architectures of hardware accelerators, such as GPUs and FPGAs. As a result, the multi-threaded uniform grid implementation accounts for a 14× speedup with respect to the serial baseline version. Accelerating the mechanical interactions through hardware acceleration proved to perform best on a GPU, with a resulting speedup of 134×.BioDynaM
Comparison of Different Optimization Techniques in Electron Lens Design
No full textTo design electron lens systems, applying a fully automated optimization routine has not yet been feasible, especially for the case where the optimization has many free variables of the lens system, such as all parameters that define the geometry of the lens electrodes and the voltage of each electrode. Hence, the study of the implementation of different optimization procedures has not yet been possible either. In one of our previous studies, we have proposed to use the so-called Second Order Electrode Method (SOEM) which performs the electrostatic field calculations in a very short time by the approximations of the field near the optical axis. There, using SOEM in field calculation, a Genetic Algorithm (GA) was successfully implemented to optimize the electron lens systems. One of the questions that has not been studied and answered in the literature yet, is whether the GA is the most suitable option among different optimization techniques for the design/optimization of electron lens systems. In this paper, by implementing the SOEM technique as the field calculation method, different optimization procedures are implemented and their performances are compared. For this study, a typical six electrode lens system is employed. The implemented optimization techniques include calculus-based local optimization (‘Fmin’) and metaheuristic methods such as GA, Particle Swarm Optimization (PSO), and Simulated Annealing (SA). The results demonstrate that the population-based global optimization techniques like GA and PSO significantly outperform single-based local optimization methods such as ‘Fmin’ and SA. Additionally, PSO shows slightly better performance than GA, although it cannot be concluded that PSO will always outperform GA for every electron lens design problem. Furthermore, in the comparison between the two single-based optimization techniques, the metaheuristic approach (SA) outperforms the calculus-based one (‘Fmin’). Hence, we recommend implementing metaheuristic, global, population-based optimization techniques like GA and PSO for the optimization electron lens systems.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ImPhys/Hagen groupHigh Voltage Technology GroupImPhys/Hoogenboom grou
The Effect of Audit Quality on the Market Value of Cash Holdings: Evidence from Tehran Stock Exchange and IACPA
No full textIn this study, the effect of audit quality on the market value of cash holdings was investigated. The company’s auditor expertise and tenure were considered as measures of audit quality. The regression model developed by Faulkender and Wang (2006) was applied to estimate the market value of cash holdings.Target sample includes 175 listed companies in the Tehran Stock Exchange during 2008-2014 (1387-1393Iranian calendars). In this study, it was supposed that audit quality affects the market value of cash holdings. The hypotheses were examined using panel data and a multivariate regression model of generalized least squares. The results indicated that the company’s auditor expertise affects the market value of cash holdings (the positive and significant relationship statistically). However, tenure does not affect the market value of cash holdings
Local versus Global Optimization of Electron Lens System Design
No full textIn electron optics, the design of electron lens systems is still a challenge. To optimize such systems, the objective function which should be calculated, depends on the electric potential distribution in the space created by the lenses. To obtain the electric potential, the existing methods are generally based on some mathematical techniques which need to mesh the space of the lens system and derive the electric potential at all mesh points. Hence, calculation of the objective function for such systems are computationally expensive. Therefore, applying a fully automatic optimization routine has not yet been feasible, especially for lens systems with many free variables. Hence, the study of objective-function landscape of such problems has not yet been performed. One of the questions of interest for optical designers, that has not been studied in the literature, is whether this problem can be solved by a local optimizer or is it necessary to apply a global optimizer. Recently we succeeded in implementing a method (based on a so-called SOEM (Second Order Electrode Method) technique) which calculates the electric potential in a fast and reasonably accurate way. In this paper, that method, is implemented to perform the study of local versus global optimization for electron lens design. The global optimization method here is performed by GA (Genetic Algorithm). The objective function is taken to be the probe size of the electron beams at the image plane. The results of our study show that the objective function of this problem has many local minima and the optimization of such problems cannot be handled by a local optimizer. GA is shown to perform well by overcoming these multiple-local minima to arrive at a global minima.Virtual/online event due to COVID-19 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ImPhys/Microscopy Instrumentation & TechniquesDC systems, Energy conversion & Storag
Length-weight and length-length relationships, condition factors and optimal length of some fish species from the Persian Gulf and Oman Sea
No full textLength-weight relationships (LWRs), relative condition factor (Krel), relative weight (Wr) and optimal length (Lopt) were calculated for five important commercial fishes from Iranian waters of the Persian Gulf and Oman Sea. Samples were collected from 2011 and December 2012 in 11 stations in three Iranian provinces (Hormuzgan, Khozestan and Sistan and baluchestan) using trawl and gillnets. Also, length-length relationships (LLRs) for Pampus argenteus and Scomberomorus commerson were computed. The values of the exponent b in the length-weight relationship ranged from 2.593 for S. commerson to 2.995 for P. argenteus. Krel varied between 1.01 ± 0.08 for Parastromateus niger and 1.06 ± 0.41 for P. argenteus. Also, Wr ranged from 59.12 ± 47.74% for S. commerson to 107.78 ± 107.29% for Eleutheronema tetradactylum. The Lopt were calculated for all five species. A negative allometric growth was found in S. commerson, while other four species (E. tetradactylum, Otolithes ruber, P. niger and P. argenteus) had isometric growth. The length-weight and length-length relationships presented here are for the first time in the Iranian coastal waters of the Persian Gulf and Oman Sea, which can provide a basis for fisheries management
Large Scale Calibration of Agent-Based Models in Social Systems with Sensitive Data
No full textComputer Engineerin
Experimental study of heat pump thermodynamic cycles using CO2 based mixtures - Methodology and first results
No full textInternational audienceThe aim of this work is to study heat pump cycles, using CO 2 based mixtures as working fluids. Since adding other chemicals to CO 2 moves the critical point and generally equilibrium lines, it is expected that lower operating pressures as well as higher global efficiencies may be reached. A simple stage pure CO 2 cycle is used as reference, with fixed external conditions. Two scenarios are considered: water is heated from 10 °C to 65 °C for Domestic Hot Water scenario and from 30 °C to 35 °C for Central Heating scenario. In both cases, water at the evaporator inlet is set at 7 °C to account for such outdoor temperature conditions. In order to understand the dynamic behaviour of thermodynamic cycles with mixtures, it is essential to measure the fluid circulating composition. To this end, we have developed a non intrusive method. Online optical flow cells allow the recording of infrared spectra by means of a Fourier Transform Infra Red spectrometer. A careful calibration is performed by measuring a statistically significant number of spectra for samples of known composition. Then, a statistical model is constructed to relate spectra to compositions. After calibration, compositions are obtained by recording the spectrum in few seconds, thus allowing for a dynamic analysis. This article will describe the experimental setup and the composition measurement techniques. Then a first account of results with pure CO 2 , and with the addition of propane or R-1234yf will be given
Conservation in an Islamic context a case study of Makkah
No full textThe Holy Qu’ rān contains many injunctions for Muslims to respect and conserve the natural environment but few address the built environment. Habitat at the time of the Prophet (PBOH) was in the vernacular and relatively impermanent. The first habitat was the cave, the second the tent and then simple flat roofed buildings of post and lintel construction made of mud and rubble. Later buildings were not indigenous but reflected the architectural styles and techniques of Muslim pilgrims from beyond the Arabian Peninsula. Permanent exotic buildings were later erected as reminders of holy places and events. This work advances a case to restore and preserve historic and religious sites in Makkah, Saudi Arabia. Makkah is the destination for millions of Muslim pilgrims who annually pay homage to Allah during the occasions of Hajj, Ramadan and Umra. The tranquillity and peaceful ambience that one associates with the holiest of Islamic experiences have, over the years, given way to jostling crowds of people who must be expediently housed, fed, transported, and protected. Due to the lack of planning and the insensitive but profitable development of the city, Makkah is in grave danger of becoming a bustling metropolis instead of a sanctuary where pilgrims gather to perform their religious rites and reaffirm their dedication to Allah. The author calls for professional planning and international cooperation to guide future development for this expanding and sensitive area. The author's ideas are grounded in practical and aesthetic study, therefore, the political, environmental and economic issues are examined in relationship to religious, historic and artistic values. The author makes proposals for a future Makkah that would provide pilgrims with the physical comforts, security, and serene environment they deserve—without destroying the city they came to visit. The author discusses preservation and conservation in the western world and the need for their acceptance in Muslim countries, the former being an aesthetic and intellectual concept sustained by law and the latter being the prescribed free expression of the individual unhindered by material considerations. Both worlds are rapidly being overwhelmed by materialism, but body, mind and spirit combine in making us aware of our surroundings and the way in what we see around us has come into being
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