On the constant roll complex scalar field inflationary models

In this paper we wish to point out the possibility of using a complex scalar field in a constant roll inflationary model, as needed for observational viability. We extend the idea of real field inflaton with constant rate of roll to a complex field, showing the feasibility of solving Einstein Klein-Gordon equations constrained by an \emph{appropriate} form of constant roll definition. As compared to the well known (two-parametric class of) real field models, there is one more degree of flexibility in constant roll inflationary solutions which is represented by an arbitrary function of time, $\gamma(t)$. We work with an arbitrary but constant function $\gamma$ (where $\gamma=0$ refers to the corresponding real field model) and find new inflationary class of potentials. In this class of models, the behavior of real and complex field models are similar in some aspects, for example the solutions with large constant roll parameter are not stable and should be considered as early time transients. These field solutions relax at late time on a dual attractor trajectory. However, complex fields phase space trajectories reach this stable regime after real fields.Comment: 21 pages, 6 figure

Oral and Dental Laser Treatments for Children: Applications, Advantages and Considerations

It is of utmost importance to make children interested in and willing to use dental services in order to prevent and treat oral diseases. Therefore, pediatric dental practitioners need to learn new technologies such as lasers, in addition to basic principles. Lasers have opened new horizons in the treatment of both soft and hard oral tissue problems in children. The present article describes application of the most commonly used lasers and their advantages and considerations

Vinyltriphenylphosphonium salt-mediated preparation of thiophene-containing electron-poor alkenes from acetylenic esters, 2-thienylmethanol and triphenylphosphine

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and alkyl acetylenecarboxylates (methyl acetylenecarboxylate, ethyl acetylenecarboxylate and ethyl phenylacetylenecarboxylate) by 2-thienylmethanol leads to vinyltriphenylphosphonium salts, which undergo an addition-elimination reaction in CH2Cl2 at room temperature to produce the corresponding O-vinylated alkenes via thiophene-containing phosphorus ylides intermediates in fairly high yields. The structural analysis of all products indicated that the reactions are regio- and stereoselective.KEY WORDS: 2-Thienylmethanol, Acetylenic ester, Vinyltriphenylphosphonium salt, O-Vinylation, Michael additionBull. Chem. Soc. Ethiop. 2011, 25(1), 91-96

Study and Analysis of Optimized Site-selection for Urban Green Space by Using Fuzzy logic: Case Study: Seventh Region of Ahvaz Municipality

Public land-uses in many cities are not able to present desirable services to citizens because of some problems such as high population density, lack of regularity in establishment and site-selection, and lack of attention to accessibility radius and population thresholds. This problem is magnified in big cities especially for land-uses such as green spaces. In urban supplying services only increasing of services is not a reason for proper supplying services but more important is optimized distribution of these centers. In this regard, present paper based on descriptive-analytical method as well as GIS follows optimized distribution of green space in the cities according to site-selection principals of urban green space. Case study is region 7 of Ahvaz municipality which has a population of 150215 persons and 2.78 green space capita, and this amount in addition to significant difference to standards determined by environment united nations (20-25 for a person), has been not distributed optimally. Regarding this city locating warm and dry zone of the earth, it is very important to select an optimized site for green spaces .Hence, in order to select a proper and optimized site for the green spaces according to site-selection principals layers (criteria) such as vicinity to residential centers, educational centers, cultural centers, urban infrastructures and establishments, commercial centers, hygienic centers, industrial centers and wastelands and etc. have been used. Research results in fuzzy logic valued region lands based on their importance in recognizing optimized location. Afterward, these lands were compared with land-use map and it was distinguished that lands with very good, good, and medium degree were placed close to residential, cultural, and educational centers which had more governmental ownership, and lands with weak and very weak degree were placed far from compatible land-uses, and were more placed close to industrial, administrative, hygienic sportive, and commercial centers which often had private ownership, therefore, they were not suggested for creating green space