Published Resarch

Abstract

In this paper, we discuss a certain nonautonomous Beverton–Holt equation of higher order. After a brief introduction to the classical Beverton–Holt equation and recent results, we solve the higher-order Beverton–Holt equation by rewriting the recurrence relation as a difference system of order one. In this process, we examine the existence and uniqueness of a periodic solution and its global attractivity. We continue our analysis by studying the corresponding second Cushing–Henson conjecture, i.e., by relating the average of the unique periodic solution to the average of the carrying capacity.

Key words: Beverton–Holt equation, Periodic environment, Logistic substitution, Matrix difference system, Periodic solution.

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http://dx.doi.org/10.1016/j.jmaa.2017.07.051

Abstract

This study explores the components of national innovation system (NIS) that most contribute to the creation of new enterprises in Baltic state countries for the period from 2005 to 2014. We run ordinary least squares (OLS) regressions for a set of variables that represents four components of NISs, extracted from principal component analysis (PCA), on the number of new enterprises as a dependent variable. We find that infrastructure and economic factors are the most influential components of the NISs in explaining changes in the number of new enterprises in the Baltic state countries. However, regulation factor is insignificant in explaining the dependent variable in Estonia and Lithuania. Moreover, the innovation factor in Latvia does not explain the variation in the number of new enterprises. Hence, it is pivotal for Estonia and Lithuania to improve the institutional and regulation structures in order to increase the number of new enterprises while Latvia needs to encourage innovative activities to capitalize on its industrial competitive advantage.

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https://doi.org/10.1007/s13132-018-0537-x

Abstract

Background and Purpose: Otomycosis is a fungal infection that frequently involves the external auditory canal. The epidemiologic data on the etiologic agents of otomycosis in Syria are very limited. In this study, we aimed to determine the fungal agents, gender distribution, and clinical presentation of otomycosis.

Materials and Methods: Two hundred and ninety nine patients (153 [51.17%] male and 146 [48.83%] female) clinically prediagnosed as otomycosis were studied at Al-mouassat University Hospital and ENT Crescent Syrian Clinic. Clinical samples were collected from the ear discharges and cultured on Sabouraud Agar.

Results: Otomycosis was diagnosed in 70 (23.4%) cases, with the highest prevalence in males aged 16-75 years (73.6%). The isolation rates of mold and yeast fungi were 75.7% and 24.3%, respectively. The most common presentations were otorrhea (98.66%), otalgia (18.06%), and hearing loss (6.35%). Our results showed that 64.28% of otomycosis agents were Aspergillus species. A. niger was the most common agent (45.7%), and 24.3% of the pathogens were C. albicans.

Conclusion: Otomycosis agents most commonly belonged to the genus of Aspergillus followed by Candida, which should be seriously considered by physicians for appropriate treatment.

Keywords: Aspergillus, Candida, Otomycosis, Syria

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http://cmm.mazums.ac.ir/article-1-155-en.pdf

Abstract

Basaltic rocks are used extensively as engineering materials including aggregates for Portland cement concrete and asphalt concrete. Syria is very rich in Basaltic rocks. There are reserves estimated to be several billion tonnes according to recent geological investigations. The annual production of concrete in Syria is about 20 million m3, containing about 35 million tonnes of aggregates.

Due to some concerns, use of basalt as concrete aggregate is very limited in Syria. Because of additional costs of transportation of dolomite aggregate produced in quarries located about 200 km far from the southern region, studying suitability of basaltic rocks occurring in As-Swaida'a region as local aggregate source would be very important. As-Swaida is basically an agricultural city.

However, it has recently witnessed urban and industrial developments. This paper is part of larger research on evaluating the basaltic rocks extracted from As-Swaida'a region, as a potential source of concrete aggregate. Effects of aggressive acidic environments on concrete have been investigated through 3 months of exposure to 5% H2S04, I 0% HCl, 5% HN03 and I 0% CH3COOH solutions. In addition, concrete permeability measured in terms of water penetration depth was evaluated for concrete after two curing time of28 and 90 days. A RCPT (Rapid chloride penetration test) has also been carried out according to ASTM C 1202. Dolomite aggregate were used for comparison. Petrographical, chemical and physical characteristics of basaltic rocks have been reported as well. The experimental results revealed that As-Swaida'a basaltic rocks were suitable for production of crushed rock aggregates for concrete production. The resistance to all acidic solutions, except H2S04 solution, was improved substantially with the use of basalt aggregate. Jn addition, the resistance to water permeation and to chloride penetration of concrete increased with the use of basalt aggregates compared with dolomite aggregate. Moreover, definite correlations were noted between some acidic attacks.

Key words: Acid resistance, aggregate, basalt. chloride penetration, durability, water permeability

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http://www.davidpublisher.org/Public/uploads/Contribute/56248bb8cf172.pdf

Abstract

This study aims at investigating the factors that affect the entrepreneurial intentions of university students in Syria. The impact of three groups of factors was investigated, demographic, personal, and external factors. The questionnaire survey method was applied. Data was collected from two major universities in Syria: Damascus University and Arab International University and two faculties: Business and Economics, and Informatics and Communication Engineering. We analyze 183 responses from the above-mentioned faculties to understand whether differences exist in entrepreneurial intentions between students from different universities and faculties. Also, we use ordinary least squares to uncover the determinants of entrepreneurial intentions for those students. The results show higher entrepreneurial intentions for Informatics and Communication Engineering and for male students. Moreover, self-efficacy, information and communication, institutional environment come to have positive and significant impacts on entrepreneurial intentions. We recommend that more polices should be directed towards developing female entrepreneurial intents. Also, entrepreneurship training courses should be offered to Informatics and Communication Engineering to enable them turn their intentions into projects. Furthermore, universities should consider establishing entrepreneurship centers, incubators and science parks that foster innovative ideas and support start-ups.

Keywords: entrepreneurial intentions self-efficacy, information and communica­tion, institutional environment, business and economics, and informatics and com­munication engineering.

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https://doi.org/10.3846/bme.2017.386