Background and Objective: Bordetella pertussis is a gram-negative cocobacilli bacterium and etiologic agent of whooping cough that in recent years, the number of its cases is on the rise. The ability of biofilm production helps this bacterium in interference with host immune system, severity of illness and antibiotic sensitivity. Thus, due to the importance of this factor, in this investigation, we tested the ability of Bordetella pertussis isolates in biofilm FORMATION.Materials and Methods: Nasopharyngeal samples were collected from persons who suspected whooping cough from throughout of Iran from 2014 to 2016 and were transferred to pertussis reference laboratory in Pasteur Institute of Iran. The bacterium in question was isolated by culture so that finally we had 20 positive samples. At the end, we performed in vitro biofilm FORMATION test for isolated strains.Results: All of the 20 clinical samples of Bordetella pertussis which in this study were examined could form biofilm and their final OD became between 0.606 and 1.212, the power of the biofilm made by them was intermediate. Conclusion: Findings of this study was similar to researches conducted by other researchers, which showed the ability of the strains of Bordetella pertussis to form biofilm and to create adverse effects on the host for example antibiotic resistance, illness severity, and so on. Thus, considering the importance of this issue, more and broader researches are needed in this area.

Background and Aim: Preserving canal curvature during different phases of canal preparation is an important point. In Endodontic therapy all efforts are made to prepare canal in a way that final canal follows the primary canal curvature. The purpose of this study was to evaluate the efficacy of root canal preparation performed by students at Endodontic Department of Dental School, Tehran University of Medical Sciences. Materials and Methods: In this retrospective study, classic method of step- back technique was investigated for preserving canal curvature in mesial roots of first mandibular molars and mesiobuccal roots of first maxillary molars between years 2000 and 2004. A randomly selected sample of 400 dental patient records was investigated by 4 observers (Endodontic department professors), searching for procedural errors. A clear explanation sheet of curvature preservation and procedural errors such as ledge FORMATION, apical foramen transportation, zipping and stripping and a questionnaire were prepared for observers. The observers went through reliability test and kappa value for agreement between every two observers. The results were above 0.8. Data were analyzed by EPI6 statistical computer program, using Chi-Square and Fisher exact test with P<0.05 as the limit of significance. Results: This study consisted of 152 first maxillary molars and 248 first mandibular molars. The prevalence of curvature preservation in mesial root of first mandibular molars and mesiobuccal root of first maxillary molars were 38.5% and 47.6% respectively. Procedural errors detected consisted of 33% ledge FORMATION, 26.1% apical foramen transportation, 1.8% zipping and 4.1% stripping for mesial root of the first mandibular molars. The results for the first maxillary molars were 27%, 19%, 3.2% and 3.2% respectively. Conclusion: The study results revealed the efficacy of endodontic education and the proficiency of junior and senior students in preparing curved posterior root canals. The results obtained in this retrospective study are comparable to prospective studies.

The interaction between syntax and word-FORMATION has been of great theoretical significance in the past four decades. The question that is now raised is as follows: is word-FORMATION an independent module, or should it be subsumed under syntax?Considering word-FORMATION processes in Persian, this article is an attempt to provide a number of facts in favour of the existence of an independent word-FORMATION component. These facts are:1. A great number of complex words in Persian are headless, contrary to the syntactic phrases.2. A great number of the Persian compounds have meanings which are predictable, yet different from their compositional meanings.3. The syntactic category of a large number of the Persian compounds is different from that of their constituent words.4. The derivational suffix “-i”, while added to nouns, may make adjectives or nouns, according to which we need to devide the Persian nouns into two subgroups. But this distinction is irrelevant in syntax.5. The Persian inflectional morphemes do not occur inside compounds.6. Compounds and syntactic phrases have different stress patterns.

This article that has studied the causes of the FORMATION of Motalefeh before the Islamic revolution of Iran was codified on the basis of placing Motalefeh in the model of categorical base of its members, namely "stratum of urban traditional medium". Thus, at first, the characteristics of the aforesaid stratum were regarded. Then by separation of the traits of this stratum, namely traditionalism and severe tendency to religion, sensitivity in sexual issues and household affairs, opposition with luxury-oriented ness, pessimism to alien symbols, negative attitude toward modern financial Institutions, threat of economic position, decadence of social situation and finally, close relation with shia clergy, these characteristics has been studied with regard to the Motalefeh in that time period. Thereby the causes establishing of this religious-political group has been analyzed.

Worldwide development of electronic commerce is undeniable and joining this manner that facilitates trading and resulting fast communication, is one of the supplements of our Internet market. In this paper we discuss ways of electronic offer and acceptance, time and place of contracting, validity and other requirements. The analysis of these subjects have been done by studying Iranian Electronic Commerce Law [ICEL], UNCITRAL Model Laws, Vienna Convention [CISG] and provisions of progressive countries in this area.

This article reviews the major teachings of policy FORMATION in modernism paradigm by deconstruction method to reconstruct the discipline in the context of postmodernism. Based on this, the first section studies the key modernism teachings such as objectivism, rationality, development, unitarianism and their impact on the modernism policy FORMATION theory. The second section introduces postmodern teachings and reforms the policy FORMATION theories in postmodern paradigm. Thus, postmodern criticism of modernism bases of policy FORMATION in denying objectivism, development and improvement, irrationality and pluralism is discussed. The article does not claim that contrary to postmodern thinkers' approach, there is postmodern policy FORMATION discipline in a metanarrative frame. Hence, the paper explains and criticizes modem policy FORMATION theories in the new context.

Semantics is a part of logic that examines the relations between language objects or terms and their referents. In this realm, such concepts as tIuth, denotation, definition, name, reference and so on are analyzed.In the present article the FORMATION of semantics, its origin, the obstacles in its way, and its historical development will be discussed. Since the discussion about the concept of truth and "the meaning effective predicate" is situated in the center of semantic investigation, and because it was in Poland that Twardowski and his students began research about the concept of truth during 1900-1930, so it is necessary to have a short account of the history of truth in Poland at the beginning of the article. Then Hilbert's attempts in metamathematics and particularly his considerable method in the analysis of metamathematical concepts will be discussed.Finally, there will be a report about the synthesis of truth and Hilbert method in the mind of Lesniewski and Tarski.Vienna Circle’s positivist thinkers opposition to Tarski's views regarding semantic analysis of truth, how Ca/'nap is convinced by Tarski in this field, and also the extension of semantics in these arguments and £n the explanatory essays of Carnap and Tarski are the subjects which have been discussed briefly at the end of this essay.