Trade Openness, Structural Change and Total Factor Productivity

Sohrab Abizadeh 한국국제경제학회 2009 International Economic Journal Vol.23 No.4

The impact of trade openness on growth of total factor productivity (TFP) is investigated. Given the differences in tradability of goods across sectors as well as the ongoing structural change, we examine whether trade openness has had a differential impact on TFP growth of the three main sectors of an economy. While the positive impact of openness on TFP growth for the aggregate economy is confirmed, openness has had no appreciable impact on the growth of TFP in the agricultural and industrial sectors. We find that the positive effect of openness on TFP growth for the economy as a whole was mostly due to the positive relationship between the two variables for the services sector. Further, we conclude that the lack of a general consensus in past studies could be due to their neglect of structural change and temporal factors when analyzing the trade-TFP nexus.

Synthesis and Characterization of Novel Poly(arylene ether)s Containing 1,3,4-Oxadiazole and Triazole Units Through Click Chemistry

Sohrab Rahmani,Amin Shafiei zadeh Mahani 한국고분자학회 2015 Macromolecular Research Vol.23 No.11

A novel bisethynyl monomer containing 1,3,4-oxadiazole unit, 2,5 bis(4-propargloxy phenyl)-1,3,4-oxadiazole, was synthesized and polymerized with diazido monomers (2,2 bis[4-(4-azidobuthyl)phenyl]propan and 1,4- diazidobutane) using ‘‘Click’’ chemistry to form novel polyaromatic ethers contining 1,3,4-oxadiazole and triazole units. The resulting polymers were characterized by using IR(infrared) and 1H NMR (nuclear magnetic resonance) techniques. The molecular weight of the resulting polymers, however, seemed relatively low according to their solution viscosity values [ηinh (inherent viscosity)=0.18 and 0.22 dL/g (deciliter/gram)]. The solubility experiments show that the obtained polymers have lower solubility in organic solvents due to their crystallinity which was confirm by X-ray diffraction but have good solubility in NMP solvent. In addition, the polymers exhibit good thermal stability and relatively high Tg (glass transition temperature) under N2 (Nitrogen) atmosphere.

Grafted Polydimethylsiloxane onto Syndiotactic Poly(styrene-co-p-methylstyrene): Synthesis and Characterization

Sohrab Rahmani,A. A. Entezami 한국고분자학회 2011 Macromolecular Research Vol.19 No.3

Syndiotactic polystyrene-graft-polydimethylsiloxane copolymers were synthesized using a two-stage process and characterized. First, the syndiotactic polystyrene copolymer, poly(styrene-co-p-methylstyrene) was prepared by the copolymerization of styrene and p-methylstyrene with cyclopentadienyltitanium trichloride/methylaluminoxane catalyst. The obtained copolymer was grafted with polydimethylsiloxane by the anionic ring-opening polymerization of hexamethylcyclotrisiloxane with a metallation reagent. The effect of the solvent on the degree of grafting in the obtained copolymers was investigated. ^1H NMR, ^13C NMR, FTIR spectroscopy and differential scanning calorimetery (DSC) were used to examine the structure and thermal behavior of the copolymers. The degree of graft was higher in THF. The melting, crystallization and glass-transition temperatures of the graft copolymers decreased with increasing degree of graft in the copolymers.

A new approach for asymptotic stability a system of the nonlinear ordinary differential equations

Sohrab Effati,A. R. Nazemi 한국전산응용수학회 2007 Journal of applied mathematics & informatics Vol.25 No.1

Modification of the effect of ambient air temperature on cardiovascular and respiratory mortality by air pollution in Ahvaz, Iran

Sohrab Iranpour,Soheila Khodakarim,Abbas Shahsavani,Ardeshir Khosravi,Koorosh Etemad 한국역학회 2020 Epidemiology and Health Vol.42 No.-

OBJECTIVES: This study investigated the modification of temperature effects on cardiovascular and respiratory mortality by air pollutants (particulate matter less than 2.5 and 10 μm in diameter [respectively], ozone, nitrogen dioxide, carbon monoxide, and sulfur dioxide). METHODS: Poisson additive models with a penalized distributed lag non-linear model were used to assess the association of air temperature with the daily number of deaths from cardiovascular and respiratory diseases in Ahvaz, Iran from March 21, 2014 to March 20, 2018, controlling for day of the week, holidays, relative humidity, wind speed, air pollutants, and seasonal and long-term trends. Subgroup analyses were conducted to evaluate the effect modification for sex and age group. To assess the modification of air pollutants on temperature effects, the level of each pollutant was categorized as either greater than the median value or less than/equal to the median value. RESULTS: We found no significant associations between temperature and cardiovascular and respiratory mortality. In the subgroup analyses, however, high temperatures were significantly associated with an increased risk of cardiovascular mortality among those 75 years old and older, with the strongest effect observed on day 0 relative to exposure. The results revealed a lack of interactive effects between temperature and air pollutants on cardiovascular and respiratory mortality. CONCLUSIONS: A weak but significant association was found between high temperature and cardiovascular mortality, but only in elderly people. Air pollution did not significantly modify the effect of ambient temperature on cardiovascular and respiratory mortality.

An Analysis of Taxation Trends in South Korea

Sohrab Abizadeh,Mahmood Yousefi 서울대학교 경제연구소 1994 Seoul journal of economics Vol.7 No.3

Scholars and policy makers marvel at the success of South Korea, a newly industrialized nation. In one generation this country has been transformed from a nation of war torn poverty to an industrial giant. This makes an examination of taxation in South Korea a worthwhile exercise. Basically, the objective of this paper is to provide an analysis of taxation trends in South Korea. This paper begins with a brief review of the economic environment in South Korea. Next, it focuses on a descriptive as well as empirical analysis of taxation trends. The paper concludes with a brief summary.

Advancements in management of graft-transmissible diseases of citrus at the citrus clonal protection program (CCPP) and national clean plant network (NCPN) in the USA

Sohrab Bodaghi,Georgios Vidalakis 한국농약과학회 2018 한국농약과학회 학술발표대회 논문집 Vol.2018 No.10

Efficacy of miltefosine compared with glucantime for the treatment of cutaneous leishmaniasis: a systematic review and meta-analysis

Sohrab Iranpour,Ali Hosseinzadeh,Abbas Alipour 한국역학회 2019 Epidemiology and Health Vol.41 No.-

Cutaneous leishmaniasis (CL) is most common form of leishmaniasis and is characterized by ulcerative skin lesions. The objective of this study was to conduct a systematic review and meta-analysis of clinical trials that compared the efficacy of miltefosine and glucantime for the treatment of CL. We searched the following databases: Cochrane, PubMed, Embase, Scopus, Web of Science, ProQuest, Cochrane Central Register of Controlled Trials, International Clinical Trials Registry Platform search portal of World Health Organization, Sid, Irandoc, Magiran, and clinicaltrials.gov. We used keywords including “miltefosine,” “glucantime,” and “Leishmania.” The quality of studies was assessed using the Cochrane risk of bias tool. A random-effects model was employed for the analysis. We assessed heterogeneity by the chi-square test and the I2 index statistic. When heterogeneity was present, meta-regression analyses were performed. The Egger method was used to assess publication bias; when it was significant, the trim-and-fill method was used to test and adjust for publication bias. A total of 1,570 reports were identified, of which 10 studies were included in the meta-analysis. In the meta-analysis, there was no significant difference between the efficacy of miltefosine and glucantime; however, subgroup analysis showed that, regarding parasite species other than Leishmania braziliensis, miltefosine was significantly superior to glucantime (intention to treat; relative risk, 1.15; 95% confidence interval, 1.01 to 1.32). In the meta-regression, only the glucantime injection type was significant at the p=0.1 level. The Egger test found statistically significant publication bias; however, including the 3 missing studies in the trim-and-fill analysis did not change the results. This meta-analysis found that miltefosine seems to be more effective than glucantime, at least in species other than L. braziliensis, for treating CL.

AC and DC Microgrids: A Review on Protection Issues and Approaches

Sohrab Mirsaeidi,Xinzhou Dong,Shenxing Shi,Bin Wang 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.6

Microgrid is a convenient, reliable, and eco-friendly approach for the integration of Distributed Generation (DG) sources into the utility power systems. To date, AC microgrids have been the most common architecture, but DC microgrids are gaining an increasing interest owing to the provision of numerous benefits in comparison with AC ones. These benefits encompass higher reliability, power quality and transmission capacity, non-complex control as well as direct connection to some DG sources, loads and Energy Storage Systems (ESSs). In this paper, main challenges and available approaches for the protection of AC and DC microgrids are discussed. After description, analysis and classification of the existing schemes, some research directions including coordination between AC and DC protective devices as well as development of combined control and protection schemes for the realization of future hybrid AC/DC microgrids are pointed out.

Reinforcement of Power System Performance Through Optimal Allotment of Distributed Generators Using Metaheuristic Optimization Algorithms

Mirsaeidi Sohrab,Li Shangru,Devkota Subash,He Jinghan,Li Meng,Wang Xiaojun,Konstantinou Charalambos,Said Dalila Mat,Muttaqi Kashem M. 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.5

Owing to the acute shortage of electric power in the majority of countries, short-term measures such as installation of Distributed Generators (DGs) have attracted much attention in recent decades. Employment of DGs can provide numerous advantages for the power systems through reduction of losses, escalation of the voltage profi le, as well as mitigation of pollutant emissions. However, in case they are not optimally allotted, they may even lead to aggravation of the network operation from diff erent aspects. The aim of this paper is to explore the optimal size and location of DGs using metaheuristic optimization algorithms so that the network performance is enhanced. The salient feature of the proposed strategy compared to the previous works is that it contemplates optimal allotment of DGs under various objectives, i.e. minimization of total network active and reactive power losses, and Cumulative Voltage Deviation (CVD), with diff erent weight values. Furthermore, the impact of enhancement in the number of DGs on diff erent aspects of power system performance is investigated. Finally, to increase the accuracy of the results, three diff erent nature-inspired optimization algorithms, i.e. Genetic Algorithm (GA), Grey Wolf Optimizer (GWO), and Particle Swarm Optimization (PSO) are deployed, and their speed in approaching the global optimum is compared with each other. The simulation results on IEEE 14-bus system indicate that the proposed strategy not only can reinforce the overall network performance through reduction of active and reactive power losses, and voltage deviation but also lead to the improvement of network voltage profi le.