Objective: This research aims to explore the applicability of the long-tail theory within the context of electronic bookstores, using the Taaghche bookstore (Taaghche.com) as the main study case. The long-tail theory posits that cultural products, especially books with low sales but wide variation, occupy the tail of the distribution, while high-selling items with limited variation are situated at the head of the distribution. The objective of this research is to demonstrate that as the tail becomes heavier, there is an increase in variation among low-sales products. Furthermore, it posits that the revenue generated from the tail could equal or even surpass the income from the head of the distribution.Methodology: This research relies on quantitative data and employs an analytical survey method for analysis. The sample, drawn from the Taaghche electronic bookstore, consists of literature storybooks that are generally well-received. The data was collected in collaboration with Taaghche and subjected to statistical analysis.Findings: The results indicate that as the number of books increases, the long-tail distribution becomes a more appropriate fit. Furthermore, by identifying the point where sales rates in the head and tail are equal, the tail of the plot lengthens and approximates the 98 percent Anderson rule. This suggests that 98 percent of the books have been sold at least once a year.Conclusion: The results present a counter-example to the Pareto principle, which suggests that an increase in the number of available books leads to increased sales of other books. It is recommended that electronic bookstores expand their range of books, as this has a positive and direct impact on the visibility of other books. The findings clearly demonstrate that increasing the number of books not only creates a long tail in sales but also enhances the visibility of other available books, which is an intriguing observation. Generally, it can be inferred that as the number of books in an electronic bookstore increases, the findings align more closely with the long tail principle. Achieving the long tail implies an increase in the variety of books, which benefits the readership. Given today’s technological advancements and the proliferation of online communication networks and electronic bookstores, many limitations of physical bookstores, such as product storage space and accessibility, have been reduced. This development allows people worldwide, with diverse interests, tastes, and fields of study, to access electronic bookstores in the shortest possible time. Now that electronic bookstores are not constrained by physical space for book storage, it is advantageous to collaborate with publishers to expand the diversity of their books as much as possible, ensuring the satisfaction and welfare of a broader audience.

Portfolio selection is an important problem in area of finance. Researchers have always tried to work with a variety of methods and strategies to achieve this important issue.In this research has been trying to present a new approach for portfolio selection with use of lower tail dependence and Extreme value theory.We show theoretically that lower tail dependence (c), a measure of the probability that a portfolio will suffer large losses given that the market does, contains important information for risk-averse investors. We then estimate c for a sample of stocks and show that it differs systematically from other risk measures including variance, semi-variance, skewness, kurtosis, beta, and coskewness. In out-of-sample tests, portfolios constructed to have low values of c outperform the market index, and portfolios with high values of c Our results indicate that c is conceptually important for risk-averse investors, differs substantially from other risk measures, and provides useful information for portfolio selection.

Background: The aim of this paper was to study the prevalence and intensity of Anisakids larvae in the long tail tuna fish captured from Iranian shores of Persian Gulf.Methods: Different organs including skin, abdominal cavity, stomach and intestinal contents, stomach sub serous tissues, liver, spleen, gonads and 20 grams of muscles of 100 long tail tuna fish (Thannus tonggol) caught from waters of the north parts of Persian Gulf were searched for anisakid nematodes larvae. Twenty grams of around the body cavity muscles were digested in artificial gastric juice. Different organs and digested muscles were examined with naked eyes for the presence of anisakids larvae. The collected larvae were preserved in 70% alcohol containing 5% glycerin, and cleared in lactophenol for identification.Results: Our findings revealed that 89% of fish harbored 3rd stage larvae of Anisakis sp. of which 2% were infected with both Anisakis and Raphidascaris. All inspected organs except that of skin were found to be infected, while stomach sub serous tissues were the most infected organ (80%) followed by abdominal cavity (10%), liver (4%), testicle (3%), stomach contents and spleen (2%) and intestinal contents (1%). Intestine and abdominal cavity were the organs harbored Raphidascaris sp. Digested muscles were free of parasite. Mean intensity was low for both species and ranged between 1.5 for Raphidascaris sp. and 3.67 for Anisaki sp.Conclusion: Anisakids larvae especially Anisakis are very prevalent in some fish including tunas of Persian Gulf, and consumption of infected fish if it is not properly cooked may lead to human anisakiasis.

The term "term" in a scientific field commonly refers to established terms in that field، which are typically single words like "essence" in philosophy، or occasionally two-word phrases such as "the primacy of existence" and "the validity of essence." The goal of this research is to explain the vital role of words that، from the perspective of experts in a particular field، may not be part of the established terminology of that science but have a significant impact on reflecting the true boundaries of knowledge within a scientific discipline when included in thesauruses. These kinds of words typically have several conditions، which are referred to as "long-tail terms." The research method is descriptive، analytical، and uses a combined approach. By analyzing the content of leading thesauruses and case studies، the opportunities resulting from the use of these types of words in thesauruses development and their impact on expanding the boundaries of knowledge are identified. The findings indicate that using these long-tail terms creates more flexibility and precision in organizing information in thesauruses. Additionally، the results suggest an increase in efficiency in knowledge management and production through the use of such innovative words

One of the factors that can be the link between our intentions and actions and their external consequences is human agency, which indicates the conscious design and intentional execution of actions by the individual in order to influence future events.Objective and Method: This research with a developmental approach of psychometric method and method 1, examines the psychometric indices of the Human Factor Characteristics Scale using the classical theory of test score measurement and the graduated question-answer theory. The purpose of this study, which included high school students in Tehran, was selected by cluster sampling of 500 people as a sample size and statistical analysis was performed on 481 data. To collect the data, the ion Human Agent Characteristics Scale (2011) was used and the research questions were evaluated using IRTPRO and SPSS software.Results:The assumption of local independence based on Pearson x2 index was established by applying Simjima's calibrated question-answer theory and the assumption of being one-dimensional based on the analysis of multidimensional question-answer theory. Diagnosis parameters with question-answer approach and classical approach Test score Both item 25 approach had the lowest and item 2 had the highest diagnosis parameter. The answer thresholds for all the questions were so far apart that no option was covered by the other option, and the options were independently selected by individuals at intervals of theta. The total scale was calculated with Cronbach's alpha of 0.945, intentionality of 0.894, foresight of 0.780, self-reactivity of 0.871 and rethinking of 0.762. Also, the role of each item in internal consistency was investigated by the loop method, which all questions had a favorable role in internal consistency of this scale. The value of the validity coefficient obtained from the question-answer theory was obtained by marginal method for intentionality 0.92, forethought 0.85, self-reaction 0.91, rethinking 0.83..