The Relationship between Predation Pressure, Demography and Genetic Diversity in Song Sparrow (Melospiza melodia) Populations

While the impacts of predators on prey demography are well studied, relatively few studies have explored how predators affect the population genetics of prey. I investigated the effects of predation pressure on genetic diversity and genetic similarity in song sparrows (Melospiza melodia) and the demographic mechanisms (births, deaths and dispersal) that may drive this relationship. I compared genetic diversity and genetic similarity (measured at 13 neutral microsatellite loci) between landscapes (island and mainland), and between populations within each landscape. In every comparison, sparrows inhabiting the landscape or population with higher nest predation were more related to one another, and in one comparison, had lower genetic diversity. High nest predation also was associated with reduced birth and population growth rates, and increased variance in reproductive success. Thus, the effects predators have on prey demography may negatively impact the genetic diversity of prey populations, beyond their effects on prey population size

Conflict-free connection numbers of line graphs

A path in an edge-colored graph is called \emph{conflict-free} if it contains at least one color used on exactly one of its edges. An edge-colored graph $G$ is \emph{conflict-free connected} if for any two distinct vertices of $G$, there is a conflict-free path connecting them. For a connected graph $G$, the \emph{conflict-free connection number} of $G$, denoted by $cfc(G)$, is defined as the minimum number of colors that are required to make $G$ conflict-free connected. In this paper, we investigate the conflict-free connection numbers of connected claw-free graphs, especially line graphs. We first show that for an arbitrary connected graph $G$, there exists a positive integer $k$ such that $cfc(L^k(G))\leq 2$. Secondly, we get the exact value of the conflict-free connection number of a connected claw-free graph, especially a connected line graph. Thirdly, we prove that for an arbitrary connected graph $G$ and an arbitrary positive integer $k$, we always have $cfc(L^{k+1}(G))\leq cfc(L^k(G))$, with only the exception that $G$ is isomorphic to a star of order at least~$5$ and $k=1$. Finally, we obtain the exact values of $cfc(L^k(G))$, and use them as an efficient tool to get the smallest nonnegative integer $k_0$ such that $cfc(L^{k_0}(G))=2$.Comment: 11 page

Experimenting with Cigarettes and Physical Activity Among Mexican Origin Youth: A Cross Sectional Analysis of the Interdependent Associations Among Sensation Seeking, Acculturation, and Gender

Sensation seeking tendencies tend to manifest during adolescence and are associated with both health-compromising behaviors and health-enhancing behaviors. The purpose of this study is to evaluate the relationship between sensation seeking and physical activity, a health-enhancing behavior, and between sensation seeking and experimenting with cigarettes, a health compromising-behavior, among a cohort of Mexican origin adolescents residing in the United States with different levels of acculturation. Methods: In 2009, 1,154 Mexican origin youth (50.5% girls, mean age 14.3 years (SD = 1.04)) provided data on smoking behavior, physical activity, linguistic acculturation, and sensation seeking. We conducted Pearson's chi(2) tests to examine the associations between categorical demographic characteristics (i.e. gender, age, country of birth and parental educational attainment) and both cigarette experimentation and physical activity and Student's t-tests to examine mean differences on the continuous variables (i.e. sensation seeking subscale) by the behaviors. We examined mean differences in the demographic characteristics, acculturation, and both behaviors for each of the sensation seeking subscales using analysis of variance (ANOVA). To examine relationships between the sensation seeking subscales, gender, and both behaviors, at different levels of acculturation we completed unconditional logistic regression analyses stratified by level of acculturation. Results: Overall, 23.3% had experimented with cigarettes and 29.0% reported being physically active for at least 60 minutes/day on at least 5 days/week. Experimenting with cigarettes and being physically active were more prevalent among boys than girls. Among girls, higher levels of sensation seeking tendencies were associated with higher levels of acculturation and experimentation with cigarettes, but not with physical activity. Among boys, higher levels of sensation seeking tendencies were associated with higher levels of acculturation, experimenting with cigarettes and being physically active. Conclusions: Our results suggest that interventions designed to prevent smoking among Mexican origin youth may need to address social aspects associated with acculturation, paying close attention to gendered manifestations of sensation seeking.National Cancer Institute CA105203, CA126988Caroline W. Law Fund for Cancer PreventionDan Duncan Family Institute for Cancer Prevention and Risk AssessmentCenter for Health Promotion and Disease Prevention Research in Underserved Population

Introduction de carnets d’apprentissage expérientiel portant sur la responsabilité sociale à l’externat au doctorat de premier cycle en médecine

Implication Statement Medical schools have a responsibility to ensure students meet and advocate for the needs of the community. However, addressing the social determinants of health is not always emphasized in clinical learning objectives. Learning logs are useful tools that can engage students to reflect on clinical encounters and direct students in their learning to target the development of highlighted skills. Despite their efficacy, the use of learning logs in medical education is largely applied towards biomedical knowledge and procedural skills. Thus, students may lack competence to address the psychosocial challenges involved in comprehensive medical care. Social accountability experiential logs were developed for third year medical students at the University of Ottawa to address and intervene on the social determinants of health. Students completed quality improvement surveys and results demonstrated this initiative to be beneficial to their learning and contributed to greater clinical confidence. Experiential logs in clinical training can be adapted across other medical schools and tailored to fit the needs and priorities of each institution’s local communities.Énoncé des implications de la recherche Les facultés de médecine ont la responsabilité de s’assurer que les étudiants répondent aux besoins de la collectivité et militent pour leur satisfaction. Or, les objectifs d’apprentissage clinique ne sont pas toujours axés sur les déterminants sociaux de la santé. L’utilité des carnets d’apprentissage est d’inciter les étudiants à réfléchir sur les rencontres cliniques et de les orienter dans leur apprentissage vers le développement des compétences ciblées. Malgré leur efficacité, les carnets d’apprentissage sont surtout appliqués aux connaissances biomédicales et aux compétences procédurales. Par conséquent, les étudiants pourraient ne pas disposer des compétences nécessaires pour relever les enjeux psychosociaux, qui sont à considérer aux fins d’une prise en charge médicale globale. Des carnets d’apprentissage expérientiel portant sur la responsabilité sociale ont été élaborés pour les étudiants en médecine de troisième année de l’Université d’Ottawa afin d’aborder et d’intervenir sur les déterminants sociaux de la santé. Les étudiants ont participé à des sondages sur l’amélioration de la qualité et les résultats de ceux-ci ont montré que cette initiative était bénéfique pour leur apprentissage et qu’elle contribuait à améliorer leur confiance en eux en tant que cliniciens. Les carnets expérientiels en formation clinique peuvent être adaptés par les diverses facultés de médecine pour qu’ils correspondent aux besoins et aux priorités des collectivités locales qu’elles desservent

Inductive Construction of 2-Connected Graphs for Calculating the Virial Coefficients

In this paper we give a method for constructing systematically all simple 2-connected graphs with n vertices from the set of simple 2-connected graphs with n-1 vertices, by means of two operations: subdivision of an edge and addition of a vertex. The motivation of our study comes from the theory of non-ideal gases and, more specifically, from the virial equation of state. It is a known result of Statistical Mechanics that the coefficients in the virial equation of state are sums over labelled 2-connected graphs. These graphs correspond to clusters of particles. Thus, theoretically, the virial coefficients of any order can be calculated by means of 2-connected graphs used in the virial coefficient of the previous order. Our main result gives a method for constructing inductively all simple 2-connected graphs, by induction on the number of vertices. Moreover, the two operations we are using maintain the correspondence between graphs and clusters of particles.Comment: 23 pages, 5 figures, 3 table

The CRISPR/Cas Adaptive Immune System of Pseudomonas aeruginosa Mediates Resistance to Naturally Occurring and Engineered Phages

Here we report the isolation of 6 temperate bacteriophages (phages) that are prevented from replicating within the laboratory strain Pseudomonas aeruginosa PA14 by the endogenous CRISPR/Cas system of this microbe. These phages are only the second identified group of naturally occurring phages demonstrated to be blocked for replication by a nonengineered CRISPR/Cas system, and our results provide the first evidence that the P. aeruginosa type I-F CRISPR/Cas system can function in phage resistance. Previous studies have highlighted the importance of the protospacer adjacent motif (PAM) and a proximal 8-nucleotide seed sequence in mediating CRISPR/Cas-based immunity. Through engineering of a protospacer region of phage DMS3 to make it a target of resistance by the CRISPR/Cas system and screening for mutants that escape CRISPR/Cas-mediated resistance, we show that nucleotides within the PAM and seed sequence and across the non-seed-sequence regions are critical for the functioning of this CRISPR/Cas system. We also demonstrate that P. aeruginosa can acquire spacer content in response to lytic phage challenge, illustrating the adaptive nature of this CRISPR/Cas system. Finally, we demonstrate that the P. aeruginosa CRISPR/Cas system mediates a gradient of resistance to a phage based on the level of complementarity between CRISPR spacer RNA and phage protospacer target. This work introduces a new in vivo system to study CRISPR/Cas-mediated resistance and an additional set of tools for the elucidation of CRISPR/Cas function

Interactions of Neuroimmune Signaling and Glutamate Plasticity in Addiction

Chronic use of drugs of abuse affects neuroimmune signaling; however, there are still many open questions regarding the interactions between neuroimmune mechanisms and substance use disorders (SUDs). Further, chronic use of drugs of abuse can induce glutamatergic changes in the brain, but the relationship between the glutamate system and neuroimmune signaling in addiction is not well understood. Therefore, the purpose of this review is to bring into focus the role of neuroimmune signaling and its interactions with the glutamate system following chronic drug use, and how this may guide pharmacotherapeutic treatment strategies for SUDs. In this review, we first describe neuroimmune mechanisms that may be linked to aberrant glutamate signaling in addiction. We focus specifically on the nuclear factor-kappa B (NF-κB) pathway, a potentially important neuroimmune mechanism that may be a key player in driving drug-seeking behavior. We highlight the importance of astroglial-microglial crosstalk, and how this interacts with known glutamatergic dysregulations in addiction. Then, we describe the importance of studying non-neuronal cells with unprecedented precision because understanding structure-function relationships in these cells is critical in understanding their role in addiction neurobiology. Here we propose a working model of neuroimmune-glutamate interactions that underlie drug use motivation, which we argue may aid strategies for small molecule drug development to treat substance use disorders. Together, the synthesis of this review shows that interactions between glutamate and neuroimmune signaling may play an important and understudied role in addiction processes and may be critical in developing more efficacious pharmacotherapies to treat SUDs