On the odd girth and the circular chromatic number of generalized Petersen graphs

A class \(\mathcal{G}\) of simple graphs is said to be girth-closed (odd-girth-closed) if for any positive integer g there exists a graph \(\mathrm {G} \in \mathcal{G}\) such that the girth (odd-girth) of \(\mathrm {G}\) is \(\ge g\). A girth-closed (odd-girth-closed) class \(\mathcal{G}\) of graphs is said to be pentagonal (odd-pentagonal) if there exists a positive integer \(g^*\) depending on \(\mathcal{G}\) such that any graph \(\mathrm {G} \in \mathcal{G}\) whose girth (odd-girth) is greater than \(g^*\) admits a homomorphism to the five cycle (i.e. is \(\mathrm {C}_{_{5}}\)-colourable). Although, the question “Is the class of simple 3-regular graphs pentagonal?” proposed by Ne?et?il (Taiwan J Math 3:381–423, 1999) is still a central open problem, Gebleh (Theorems and computations in circular colourings of graphs, 2007) has shown that there exists an odd-girth-closed subclass of simple 3-regular graphs which is not odd-pentagonal. In this article, motivated by the conjecture that the class of generalized Petersen graphs is odd-pentagonal, we show that finding the odd girth of generalized Petersen graphs can be transformed to an integer programming problem, and using the combinatorial and number theoretic properties of this problem, we explicitly compute the odd girth of such graphs, showing that the class is odd-girth-closed. Also, we obtain upper and lower bounds for the circular chromatic number of these graphs, and as a consequence, we show that the subclass containing generalized Petersen graphs \(\mathrm {Pet}(n,k)\) for which either k is even, n is odd and \(n\mathop {\equiv }\limits ^{k-1}\pm 2\) or both n and k are odd and \(n\ge 5k\) is odd-pentagonal. This in particular shows the existence of nontrivial odd-pentagonal subclasses of 3-regular simple graphs.     

An Agent‐Based Model for Pathogen Persistence and Cross‐Contamination Dynamics in a Food Facility

We used an agent‐based modeling (ABM) framework and developed a mathematical model to explain the complex dynamics of microbial persistence and spread within a food facility and to aid risk managers in identifying effective mitigation options. The model explicitly considered personal hygiene practices by food handlers as well as their activities and simulated a spatially explicit dynamic system representing complex interaction patterns among food handlers, facility environment, and foods. To demonstrate the utility of the model in a decision‐making context, we created a hypothetical case study and used it to compare different risk mitigation strategies for reducing contamination and spread of Listeria monocytogenes in a food facility. Model results indicated that areas with no direct contact with foods (e.g., loading dock and restroom) can serve as contamination niches and recontaminate areas that have direct contact with food products. Furthermore, food handlers’ behaviors, including, for example, hygiene and sanitation practices, can impact the persistence of microbial contamination in the facility environment and the spread of contamination to prepared foods. Using this case study, we also demonstrated benefits of an ABM framework for addressing food safety in a complex system in which emergent system‐level responses are predicted using a bottom‐up approach that observes individual agents (e.g., food handlers) and their behaviors. Our model can be applied to a wide variety of pathogens, food commodities, and activity patterns to evaluate efficacy of food‐safety management practices and quantify contamination reductions associated with proposed mitigation strategies in food facilities.     

Pluralistic media ignorance: Presence and causes

This study examines the presence and causes of pluralistic media ignorance - incorrect estimation of media content in a way that creates the impression that popular broadcasting is overabundant with morally controversial material. Using the appearance of sexual content in television advertising in Israel as a case study, we compare survey estimates (N = 305) of the prevalence of this material with its actual level according to the findings of a content analysis of commercials (N = 752). Pluralistic media ignorance emerges as a predominant norm, when viewers are requested to estimate the prevalence of “soft core” content like kissing and partial nudity, but it is a minor phenomenon, when estimating the share of more explicit material such as intercourse, homosexuality and rape. The most prominent predictors of pluralistic media ignorance are disapproval of the inclusion of objectionable content in popular media and extended recall of media exemplars that contain such content. Religiosity, ethnicity and sex are only partly predicting the emergence of pluralistic media ignorance. Media consumption, fear of media influence and other demographics are not predicting it at all. Public policy implications are discussed and suggestions for future research are given.     

Alterations in IGF-I affect elderly: role of physical activity

The growth hormone–insulin-like growth factor I (IGF-I) axis is an important physiological regulator muscle for development. Although there is evidence that aging muscle retains the ability to synthesize IGF-I, there is also evidence that aging may be associated with attenuation of the ability of exercise to induce an isoform of IGF-I that promotes satellite cell proliferation. However, it is clear that overexpression of IGF-I in the muscle can protect against age-related sarcopenia. Strength training appears to be the intervention of choice for the prevention and treatment of sarcopenia. IGF-I has been implicated in the loss of the muscle with age, and IGF-I expression levels change as a consequence of strength training in older adults. However, it seems that advancing age, rather than declining serum levels of IGF-I, appears to be a major determinant of life-time changes in body composition in women and men. We concluded that resistive exercise is a significant determinant of muscle mass and function. Elevated levels of IGF-I have been found in physically active compared to sedentary individuals. Recent work suggests that IGF-I as a mediator plays an important role in muscle hypertrophy and angiogenesis, both of which characterize the anabolic adaptation of muscles to exercise.     

Internal Migration of Ethno‐national Minorities: The Case of Arabs in Israel

Recent scholarship emphasizes differences among ethnic groups' internal migration patterns. Yet, with few exceptions, research has focused on the Anglo‐American world, neglecting experiences from other regions. This paper is part of a larger research project that studies mobility among the Arab minority in Israel and its driving forces. In this paper we examine patterns of internal migration by analysing the propensity to migrate as well as migrants' individual and social characteristics. First, we survey the theoretical backdrop that is suggested by recent geographic literature on internal migration among ethnic and racial minorities, including native groups. Second, we contextualize the group studied, providing necessary background information on the political, socio‐economic and demographic conditions of Arabs in Israel. We briefly discuss attributes that are – or have been – potential hindering factors to Arab mobility in the Jewish state. Finally, we analyse 1995 national census data at the micro scale and provide a basis for future explanations of the phenomenon. We conclude by outlying some future directions in the study of internal migration of minorities in Israel.     

Media, Racism and Islamophobia: The Representation of Islam and Muslims in the Media

This article examines the representation of Islam and Muslims in the British press. It suggests that British Muslims are portrayed as an 'alien other' within the media. It suggests that this misrepresenatation can be linked to the development of a 'racism', namely, Islamphobia that has its roots in cultural representations of the 'other'. In order to develop this arguement, the article provies a summary/overview of how ethnic minorities have been represented in the British press and argues that the treatment of British Muslims and Islam follows these themes of 'deviance' and 'un-Britishness'.     

Forced online: push factors of internet sexuality: A preliminary study of online paraphilic empowerment

Online sexual behavior may be more completely explained by integrating a Pull Factor analysis, centering on the characteristics of the Internet that make it an appealing outlet for sexuality (e.g., "Triple A Engine") and a Push Factor analysis, centering on characteristics of the offline world that disallow fulfillment of sexual desires. This new framework is utilized in explaining paraphilic (unconventional) sexualities online. Because paraphilics are members of highly concealable, horizontal and rare sexual minorities, they are pushed online by mainstream society. Online, paraphilics interact with similar others, and through lurking, re-learning and self-disclosing, may become sexually empowered. Clinical ramifications of attainment of positive sexual-social identity via empowerment are discussed, as are possible affects on public policy.