Maltreatment, psychiatric symptoms and human immunodeficiency virus/sexual transmitted infection risk behavior among youth with alcohol and other drug use problems: A person-centered analysis

Multi-problem youth undergoing treatment for substance use problems are at high behavioral risk for exposure to sexually transmitted infections (STIs), including human immunodeficiency virus (HIV). Specific risk factors include childhood adversities such as maltreatment experiences and subsequent forms of psychopathology. The current study used a person-centered analytical approach to examine how childhood maltreatment experiences were related to patterns of psychiatric symptoms and HIV/STI risk behaviors in a sample of adolescents (N = 408) receiving treatment services. Data were collected in face-to-face interviews at two community-based facilities. Descriptive statistics and Latent Profile Analysis (LPA) were used to (a) classify adolescents into groups based on past year psychiatric symptoms, and (b) examine relations between class membership and forms of childhood maltreatment experiences, as well as past year sexual risk behavior (SRB). ^ LPA results indicated significant heterogeneity in psychiatric symptoms among the participants. The three classes generated via the optimal LPA solution included: (a) a low psychiatric symptoms class, (b) a high alcohol symptoms class and (c) a high internalizing symptoms class. Class membership was associated significantly with adolescents’ self-reported scores for childhood sexual abuse and emotional neglect. ANOVAs documented significant differences in mean scores for multiple indices of SRB indices by class membership, demonstrating differential risk for HIV/STI exposure across classes. The two classes characterized by elevated psychiatric symptom profiles and more severe maltreatment histories were at increased behavioral risk for HIV/STI exposure, compared to the low psychiatric symptoms class. The high internalizing symptoms class reported the highest scores for most of the indices of SRB assessed. The heterogeneity of psychiatric symptom patterns documented in the current study has important implications for HIV/STI prevention programs implemented with multi-problem youth. The results highlight complex relations between childhood maltreatment experiences, psychopathology and multiple forms of health risk behavior among adolescents. The results underscore the importance of further integration between substance abuse treatment and HIV/STI risk reduction efforts to improve morbidity and mortality among vulnerable youth. ^

The effect of male -male competition and its underlying regulatory mechanisms on the electric signal of the gymnotiform fish Brachyhypopomus gauderio

Sexually-selected communication signals can be used by competing males to settle contests without incurring the costs of fighting. The ability to dynamically regulate the signal in a context-dependent manner can further minimize the costs of male aggressive interactions. Such is the case in the gymnotiform fish Brachyhypopomus gauderio, which, by coupling its electric organ discharge (EOD) waveform to endocrine systems with circadian, seasonal, and behavioral drivers, can regulate its signal to derive the greatest reproductive benefit. My dissertation research examined the functional role of the EOD plasticity observed in male B. gauderio and the physiological mechanisms that regulate the enhanced male EOD. To evaluate whether social competition drives the EOD changes observed during male-male interactions, I manipulated the number of males in breeding groups to create conditions that exemplified low and high competition and measured their EOD and steroid hormone levels. My results showed that social competition drives the enhancement of the EOD amplitude of male B. gauderio. In addition, changes in the EOD of males due to changes in their social environment were paralleled by changes in the levels of androgens and cortisol. I also examined the relationship between body size asymmetry, EOD waveform parameters, and aggressive physical behaviors during male-male interactions in B. gauderio, in order to understand more fully the role of EOD waveforms as reliable signals. While body size was the best determinant of dominance in male B. gauderio, EOD amplitude reliably predicted body condition, a composite of length and weight, for fish in good body condition. To further characterize the mechanisms underlying the relationship between male-male interactions and EOD plasticity, I identified the expression of the serotonin receptor 1A, a key player in the regulation of aggressive behavior, in the brains of B. gauderio. I also identified putative regulatory regions in this receptor in B. gauderio and other teleost fish, highlighting the presence of additional plasticity. In conclusion, male-male competition seems to be a strong selective driver in the evolution of the male EOD plasticity in B. gauderio via the regulatory control of steroid hormones and the serotonergic system.

Maltreatment, Psychiatric Symptoms and Human Immunodeficiency Virus/Sexual Transmitted Infection Risk Behavior Among Youth with Alcohol and Other Drug Use Problems: A Person-Centered Analysis

Multi-problem youth undergoing treatment for substance use problems are at high behavioral risk for exposure to sexually transmitted infections (STIs), including human immunodeficiency virus (HIV). Specific risk factors include childhood adversities such as maltreatment experiences and subsequent forms of psychopathology. The current study used a person-centered analytical approach to examine how childhood maltreatment experiences were related to patterns of psychiatric symptoms and HIV/STI risk behaviors in a sample of adolescents (N = 408) receiving treatment services. Data were collected in face-to-face interviews at two community-based facilities. Descriptive statistics and Latent Profile Analysis (LPA) were used to (a) classify adolescents into groups based on past year psychiatric symptoms, and (b) examine relations between class membership and forms of childhood maltreatment experiences, as well as past year sexual risk behavior (SRB). LPA results indicated significant heterogeneity in psychiatric symptoms among the participants. The three classes generated via the optimal LPA solution included: (a) a low psychiatric symptoms class, (b) a high alcohol symptoms class and (c) a high internalizing symptoms class. Class membership was associated significantly with adolescents’ self-reported scores for childhood sexual abuse and emotional neglect. ANOVAs documented significant differences in mean scores for multiple indices of SRB indices by class membership, demonstrating differential risk for HIV/STI exposure across classes. The two classes characterized by elevated psychiatric symptom profiles and more severe maltreatment histories were at increased behavioral risk for HIV/STI exposure, compared to the low psychiatric symptoms class. The high internalizing symptoms class reported the highest scores for most of the indices of SRB assessed. The heterogeneity of psychiatric symptom patterns documented in the current study has important implications for HIV/STI prevention programs implemented with multi-problem youth. The results highlight complex relations between childhood maltreatment experiences, psychopathology and multiple forms of health risk behavior among adolescents. The results underscore the importance of further integration between substance abuse treatment and HIV/STI risk reduction efforts to improve morbidity and mortality among vulnerable youth.

The Effect of male-male competition and its Underlying Regulatory Mechanisms on the Electric Signal of the Gymnotiform fish Brachyhypopomus gauderio

Sexually-selected communication signals can be used by competing males to settle contests without incurring the costs of fighting. The ability to dynamically regulate the signal in a context-dependent manner can further minimize the costs of male aggressive interactions. Such is the case in the gymnotiform fish Brachyhypopomus gauderio, which, by coupling its electric organ discharge (EOD) waveform to endocrine systems with circadian, seasonal, and behavioral drivers, can regulate its signal to derive the greatest reproductive benefit. My dissertation research examined the functional role of the EOD plasticity observed in male B. gauderio and the physiological mechanisms that regulate the enhanced male EOD. To evaluate whether social competition drives the EOD changes observed during male-male interactions, I manipulated the number of males in breeding groups to create conditions that exemplified low and high competition and measured their EOD and steroid hormone levels. My results showed that social competition drives the enhancement of the EOD amplitude of male B. gauderio. In addition, changes in the EOD of males due to changes in their social environment were paralleled by changes in the levels of androgens and cortisol. I also examined the relationship between body size asymmetry, EOD waveform parameters, and aggressive physical behaviors during male-male interactions in B. gauderio, in order to understand more fully the role of EOD waveforms as reliable signals. While body size was the best determinant of dominance in male B. gauderio, EOD amplitude reliably predicted body condition, a composite of length and weight, for fish in good body condition. To further characterize the mechanisms underlying the relationship between male-male interactions and EOD plasticity, I identified the expression of the serotonin receptor 1A, a key player in the regulation of aggressive behavior, in the brains of B. gauderio. I also identified putative regulatory regions in this receptor in B. gauderio and other teleost fish, highlighting the presence of additional plasticity. In conclusion, male-male competition seems to be a strong selective driver in the evolution of the male EOD plasticity in B. gauderio via the regulatory control of steroid hormones and the serotonergic system.

The effects of dietary omega-3 fatty acids on brain function are sex, age and brain-region specific

Omega (n)-3 polyunsaturated fatty acids (PUFA) have beneficial effects in neuropsychiatric illnesses. The goals of this thesis were to determine the effects of feeding diets varying in n-3 PUFA on brain fatty acid composition, and neurotrophin and myelin-related gene expression of the brain in an age, sex, and region-specific manner. A diet high in n-3 PUFA altered phospholipid docosahexaenoic acid (DHA) and oleic acid composition in an age, sex, and region-specific manner. Diet had no effect on the mRNA expression of brain-derived neurotrophic factor (BDNF) and tropomyosin-receptor kinase-B (TrkB); however, stearoyl-CoA desaturase-1 (SCD1) and myelin basic protein (MBP) gene expression increased in offspring fed a diet high in n-3 PUFA in an age, sex, and region-specific manner. DHA treatment to ex vivo cerebral cortical cells showed an increase in BDNF, TrkB, SCD1, and MBP mRNA expression compared to control cells. The mRNA expression of BDNF and SCD1 was higher in DHA treated cells compared to arachidonic acid treated cells. Overall, the data presented in this thesis suggests that the potential benefits of n-3 PUFA on brain function are sex, age and brain-region specific.

Relação Entre Motivação e Desempenho Escolar em Alunos do 1º Ciclo

O presente estudo teve como objectivo analisar a existência de uma possível relação entre motivação (intrínseca ou extrínseca) e o desempenho escolar em alunos do 1º ciclo que frequentam o 4º ano. A amostra foi constituída por 62 alunos, com idades compreendidas entre os 9 e 10 anos, 15 que frequentavam a Escola Básica do 1º Ciclo de Brancas e 47 a Escola Básica da Batalha (24 alunos da Turma A e 23 da Turma B). Considerando a possível existência de variáveis sociodemográficas associadas ao desempenho, no processo de recolha de dados foi aplicado um questionário sóciodemográfico, que pela sua potencial natureza descritiva, interpretativa e reflexiva, constituiu uma importante ferramenta na análise e avaliação dos resultados obtidos. Com o objectivo de avaliar a motivação (intrínseca e extrínseca) foi administrada uma escala de motivação escolar, aferida para a população portuguesa contendo 18 questões. Cada uma destas questões contém 4 possibilidades de resposta (duas referentes à motivação intrínseca e outras duas referentes à motivação extrínseca). Quanto ao desempenho escolar, este foi avaliado através das notas que os alunos obtiveram no final do ano lectivo e que foram facultadas pelas professoras dos mesmos. A análise dos resultados evidenciou que existe uma relação entre a motivação e o desempenho escolar, concluindo-se que os alunos intrinsecamente motivados apresentam melhor desempenho do que os alunos extrinsecamente motivados. Consideramos deste modo, que a implementação de estratégias na sala de aula que promovam a motivação intrÍnseca será mais benéfico para o sucesso escolar dos alunos. / The objective of this study, is to analyze the possible relation between intrinsic and extrinsic motivation and the educational achievement in students in the fourth grade of grade school. The sample was composed by 62 students, with a ages between 9 and 10 years of age. 15 students of this sample attended the grade school of Brancas, 47 attended the grade school of Batalha ( 24 of the students are from class A and 23 are from class B). Considering a possible existence of sociodemographic variables related to achievement, in the process of data collecting, a sociodemographic questionnaire was used, considering its great potential to describe, interpret analyze and evaluate the results obtained. To evaluate intrinsic and extrinsic motivation, a scale of school motivation adapted for Portuguese population with eighteen questions was applied. Each of these questions has 4 possibilities of response (two referring to intrinsic motivation and two referring to extrinsic motivation). In what concerns to school achievement, this was evaluated trough school grades obtained at the end of the school year given by the teachers. The analyses of the results demonstrated that there are differences between motivation and school achievement, concluding that the students with intrinsic motivation present better achievement then the students with extrinsic motivation. The implementation of strategies in the classroom, will promote intrinsic motivation and bring more success to students.

Performance en fluage des assemblages antiglissement avec des surfaces métallisées dans les ponts en acier

Les éléments des ponts en acier sont exposés à de sévères conditions environnementales, tel l’épandage de sels déglaçant sur les routes. Ces éléments ont besoin d’un niveau suffisant de protection contre la corrosion afin de préserver leur intégrité à long terme. Une solution efficace, devenue populaire au Canada, est la métallisation. La métallisation est un revêtement anticorrosion formé par projection thermique de métal, généralement du zinc, sur la surface à protéger. La protection fournie au substrat d’acier est assurée par une barrière physique et une protection galvanique. Pour le calcul des assemblages boulonnés antiglissement, les codes de conception, tel le code Canadien sur le calcul des ponts routiers CAN/CSA S6-14, spécifient, en fonction des conditions des surfaces de contact désirées, un coefficient de glissement à utiliser. Actuellement, ces codes ne fournissent aucun coefficient de glissement entre deux surfaces métallisées. Donc, il est pratique courante pour les fabricants de ponts en acier de masquer les surfaces de contact des joints boulonnés avant de métalliser, ce qui est très couteux pour l’industrie puisque ce travail doit se faire manuellement. Récemment, des études ont évalué la résistance au glissement à court terme d’assemblages antiglissement ayant des surfaces de contact métallisées. Les résultats ont révélé une résistance au glissement supérieure aux assemblages sur acier nu grenaillés. Dans la présente recherche, la performance en fluage des assemblages antiglissement métallisés a été caractérisée pour s’assurer qu’une résistance en glissement de Classe B soit toujours valide à long terme. L’effet de la relaxation de la force de serrage sur la charge de glissement a aussi été évalué. Les résultats ont démontré une bonne performance en fluage. Aussi, les résultats ont révélé que la relaxation de la force de serrage n’a pas d’impact significatif sur la résistance au glissement des assemblages antiglissement métallisés. Les conclusions de cette étude pourraient bien influencer de futures révisions des codes de conception et avoir un impact sur l’industrie de l’acier en Amérique du Nord.Mots clés : Assemblage boulonné antiglissement, métallisation, pont routier en acier, fluage, relaxation

Apprendre avec la technologie : l'impact sur l'enseignement et l'apprentissage de l’utilisation de la technologie numérique (SMARTBOARD) dans les classes

This research was devoted to gaining information on teachers? use of technology, specifically SMARTBOARD technology, for teaching and promoting learning in the classroom. Research has suggested that use of technology can enhance learning and classroom practices. This has resulted in administrators encouraging the use of SMARTBOARDS, installing them in classrooms and providing training and support for teachers to use this technology. Adoption of new technology, however, is not simple. It is even more challenging because making the best use of new technologies requires more than training; it requires a paradigm shift in teachers? pedagogical approach. Thus, while it may be reasonable to believe that all we need to do is show teachers the benefits of using the SMARTBOARD; research tells us that changing paradigms is difficult for a variety of reasons. This research had two main objectives. First, to discover what factors might positively or negatively affect teachers? decisions to take up this technology. Second, to investigate how the SMARTBOARD is used by teachers who have embraced it and how this impacts participation in classrooms. The project was divided into two parts; the first was a survey research (Part 1), and the second was an ethnographic study (Part 2). A thirty-nine item questionnaire was designed to obtain information on teachers? use of technology and the SMARTBOARD. The questionnaire was distributed to fifty teachers at two EMSB schools: James Lyng Adult Centre (JLAC) and the High School of Montreal (HSM). Part 2 was an ethnographic qualitative study of two classes (Class A, Class B) at JLAC. Class A was taught by a male teacher, an early-adopter of technology and a high-level user of the SMARTBOARD; Class B was taught by a female teacher who was more traditional and a low-level user. These teachers were selected because they had similar years of experience and general competence in their subject matter but differed in their use of the technology. The enrollment in Class A and Class B were twenty-three and twenty-four adult students, respectively. Each class was observed for 90 minutes on three consecutive days in April 2010. Data collection consisted of videotapes of the entire period, and observational field notes with a graphical recording of participatory actions. Information from the graphical recording was converted to sociograms, a graphic representation of social links among individuals involved in joint action. The sociogram data was tabulated as quantified data. The survey results suggest that although most teachers are interested in and use some form of technology in their teaching, there is a tendency for factors of gender and years of experience to influence the use of and opinions on using technology. A Chi Square analysis of the data revealed (a) a significant difference (2 = 6.031, p < .049) for gender in that male teachers are more likely to be interested in the latest pedagogic innovation compared to female teachers; and, (b) a significant difference for years of experience (2 = 10.945, p < .004), showing that teachers with ?6 years experience were more likely to use the SMARTBOARD, compared to those with more experience (>6 years). All other items from the survey data produced no statistical difference. General trends show that (a) male teachers are more willing to say yes to using the SMARTBOARD compared to female teachers, and (b) teachers with less teaching experience were more likely to have positive opinions about using the SMARTBOARD compared to teachers with more experience. The ethnographic study results showed differences in students? response patterns in the two classrooms. Even though both teachers are experienced and competent, Teacher A elicited more participation from his students than Teacher B. This was so partly because he used the SMARTBOARD to present visual materials that the students could easily respond to. By comparison, Teacher B used traditional media or methods to present most of her course material. While these methods also used visual materials, students were not able to easily relate to these smaller, static images and did not readily engage with the material. This research demonstrates a generally positive attitude by teachers towards use of the SMARTBOARD and a generally positive role of this technology in enhancing students? learning and engagement in the classroom. However, there are many issues related to the SMARTBOARD use that still need to be examined. A particular point is whether teachers feel adequately trained to integrate SMARTBOARD technology into their curricula. And, whether the gender difference revealed is related to other factors like a need for more support, other responsibilities, or a general sense of anxiety when it comes to technology. Greater opportunity for training and ongoing support may be one way to increase teacher use of the SMARTBOARD; particularly for teachers with more experience (>6 years) and possibly also for female teachers.

Vidéos contre lectures: Une évaluation de l'utilisation de vidéos pour accomplir la construction initiale de connaissances

Abstract : The goal of this study was to determine whether providing videos for students to watch before class would be more effective than assigning readings. The study took place within a flipped classroom: a methodology designed to engage students in the initial construction of knowledge before class, freeing up classroom time for active learning pedagogies. Preparing for class by watching videos should require less of the students’ time than doing readings, and they should respond better to videos than to readings because these more closely mimic this generation’s interactions with information and media. Consequently, flipped classroom students provided with videos should perceive a lower workload, which could translate into more positive learning outcomes. From an instructor’s perspective, however, developing and organizing videos is extremely time consuming. Thus, a teacher giving consideration to flipping their class would likely want to know whether videos would lead to positive outcomes for their students before actually committing to developing these. However, no research to date was identified which has examined the question of whether flipped class videos would be more effective than readings. The hypotheses for the study were that videos would result in measurable learning gains for the students, and would lead to lower time demands and perceived workloads, as well as more positive attitudes. These were tested using a quasi-experimental design involving a convenience sample of two small college General Biology 1 courses taught by the same teacher. One group had videos to watch before class for the first 1/3 of the course (treatment; Class A), during which the other was assigned readings (control; Class B). Following this, both groups were provided with videos. Student scores were compared on pre-instruction and in-class quizzes, activities, four unit tests, and a final exam. Further, students completed a 44 item survey as well as a demographic questionnaire. Results suggest greater learning gains for students provided with videos. Certainly, students from Class B improved significantly when provided with videos, especially as compared to Class A, whose improvement over the same time span was marginal. However, conclusions based on these results are somewhat tentative, as Class A performed rather poorly on all summative assessments, and this could have driven the patterns observed, at least partially. From the surveys, Class B students reported that they spent more time preparing for class, were less likely to do the necessary preparations, and generally perceived their effort and workload levels to be higher. These factors were significant enough that they contributed to four students from Class B (10% of the class) dropping the course over the semester. In addition, students from both groups also reported more positive attitudes towards videos than readings, although they did not necessarily feel that videos were (or would be) a more effective study and learning tool. The results of this study suggest that any effort on the part of an instructor to prepare or organize videos as pre-class instructional tools would likely be well spent. However, even outside of the context of a flipped classroom, this study provides an indication that assigned readings can place heavy workload requirements on students, which should give cause for any instructor employing mandatory readings to reassess their approach. Finally, since both groups were statistically equivalent across all measured demographic variables, it appears that some of the observed disparities in assessment scores may have been driven by differences in group dynamics. Consequently, the suggestion is made that an instrument to measure classroom climate should be incorporated into any research design comparing two or more interacting groups of students, as group dynamics have the potential to play a key role in any outcomes.||Résumé : L'objectif de cette étude était de déterminer si fournir des vidéos aux étudiants avant une classe serait plus efficace comme méthode d’apprentissage individuel que de leur donner une liste de lectures à compléter. L'étude a eu lieu dans une classe renversée – une stratégie plus reconnu sous le nom de «classroom flipping» – ce qui ce trouve à être une méthodologie qui vise à obliger les élèves d’accomplir le transfert de connaissances initial avant la classe, en vue de libérer du temps de classe pour des activités pédagogiques plus approfondie. En théorie, pour les élèves, se préparer pour une classe renversé en regardant des vidéos devrait exiger moins de temps que d’être obligé à apprendre le matériel en lisant. En plus, présenter le matériel d’un cours avec des vidéos imite de plus près les genres d’interactions qu’on les étudiants de cette génération avec de l'information et les médias, ce qui devrait faciliter leur tâche. Par conséquent, les élèves d’une classe renversée fournies avec des vidéos devraient percevoir une charge de travail moins élevée, et ceci pourrait se traduire en bilans d'apprentissage plus positifs. Cependant, du point de vue du professeur, avoir à développer et organiser des vidéos se présente comme un gros défi, surtout en vue du temps et de l’effort qui sont requis. Ainsi, un enseignant qui songe à renversée sa classe voudrait probablement savoir si le fait d’offrir des vidéos mène à des résultats positifs avant de réellement s'engager dans le développement de ces derniers. Par contre, lors de l’écriture de ce texte, aucune étude n’a été identifié qui répond à cette question, et aucune publication compare la performance des étudiants lorsqu’ils ont des vidéos à regarder avec lorsqu’ils sont obligés de faire de la lecture pour se préparer. Alors, les hypothèses de l'étude étaient que des étudiants ayant accès à des vidéos démontreraient des gains d’apprentissages évidents, qu’ils apercevraient des requêtes de temps moins encombrantes et une charge de travail plus faible, et, en vue de ces derniers, que les étudiants auraient des attitudes plus positives envers le cours et le matériel. Les hypothèses ont été testés à l'aide d'un modèle quasi-expérimental, avec comme échantillon deux classes collégiales de Biologie générale 1, tout les deux enseignés par le même professeur. Un de ces groupes avaient accès à des vidéos pour se préparer pour chaque classe lors du premier tiers du cours, alors que l’autre groupe étaient obligé de faire de la lecture. Après le premier tiers du cours, ce qui fut 10 des 30 classes du semestre, les deux groupes ont été fournis avec des vidéos pour le restant du cours. Des notes ont été ramassées et comparées sur des mini-examens préparatoires avant et durant les classes, sur des activités complétées en classe, sur quatre examens en classe, et un examen final. En outre, les étudiants ont rempli un questionnaire composé de 44 items, ainsi qu’un autre questionnaire démographique. Les résultats de l’étude suggèrent qu’une décision d’offrir des vidéos aux élèves peut mener à des gains d'apprentissage plus élevés comparativement à l’option lecture. En particulier, les élèves du groupe initial de lecture se sont considérablement améliorées lorsqu'ils ont été fournis avec des vidéos, surtout par rapport au groupe initial de vidéos, dont l’amélioration durant la même période était marginale. Cependant, ces conclusions sont un peu incertaines, parce que la performance du groupe initial de vidéos était globalement médiocre, ce qui aurait pu mener aux résultats observés. Par contre, les résultats obtenus des questionnaires étaient moins incertains, et indiquent que les élèves qui se sont vues attribués des lectures passaient plus de temps pour préparer leurs classes, étaient plus aptes à ne pas faire les préparatifs nécessaires, et ont aperçus leurs niveaux d'efforts et leurs charges de travails comme étant plus élevés. Ces facteurs étaient suffisamment importants qu'ils ont contribué au fait que quatre étudiants du groupe de lecture, soit 10% de la classe, ont abandonnés le cours durant le premier tiers du semestre. Finalement, les élèves ont démontrés des attitudes plus positives envers les vidéos, bien qu'ils ne trouvaient pas nécessairement que ceux-ci étaient plus efficaces que les lectures lorsqu’ils voulaient étudier pour les examens. Basé sur ces résultats, il est possible de conclure que tout effort de la part d'un instructeur pour préparer ou organiser des vidéos pédagogiques serait probablement un bon investissement. En plus, et même en dehors du contexte d'une classe renversée, cette étude offre une indication qu’une stratégie pédagogique qui oblige les étudiants à faire beaucoup de lecture peut imposer des exigences et une charge de travail très élevée pour les étudiants, ce qui devrait donner cause à tout instructeur qui attribue des lectures à réévaluer leur approche. Enfin, puisque les deux groupes étaient équivalents d’un point de vue statistique sur toutes les mesures démographiques, il semble que certaines disparités entre les deux groupes dans les notes d'évaluation et d’examens peuvent possiblement avoir été entraînées par des différentes dynamiques dans chaque group. Par conséquent, il est suggéré que des mesures de relations entre étudiants et de dynamiques de groupes devraient être incorporé dans n’importe qu’elle recherche comparant deux ou plusieurs groupes d’étudiants, et surtout quand ces étudiants sont en interaction, parce-que en toute apparence les dynamiques de groupes ont le potentiel de jouer un rôle clé dans les résultats obtenus.

Effect of light-sticks and electralunie attractors on surface-longline catches of swordfish (Xiphias gladius, Linnaeus, 1959) in the southwest equatorial Atlantic

Two experimental fishing trials were carried out off the coast of Pernambuco, Brazil, in 1999 and 2001, using a small artisanal longliner. In experiment 1, six-hook baskets with three chemical light-sticks on alternating hooks had significantly higher catch rates than those with zero or with a light-stick on every hook, with most swordfish accounted for by hooks with light-sticks. Analysis of the data from experiment 2 showed no significant difference between electralume attractors, consisting of AA lithium batteries protected by a solid cover and light-sticks that produce a fluorescent light when two chemical products are mixed. Significant differences were detected in mean CPUE by size class, with most swordfish belonging to class 'b' (125-170 cm lower jaw to fork length (LJFL)). No differences, however, were found for swordfish catches in classes 'a' (< 125 cm LJFL) and V, and no evidence was found of interaction between the two factors (attractor and size class). Although there was no significant difference between the total length-frequency distributions of swordfish caught with light-sticks and electralume attractors, signibcant differences were found for fish smaller than 125 cm LJFL, with electralume catches consisting of smaller swordfish than those of gear using light-sticks. (c) 2004 Elsevier B.V. All rights reserved.

Effect of light-sticks and electralume attractors on surface-longline catches of swordfish (Xiphias gladius, Linnaeus, 1959) in the southwest equatorial Atlantic

Two experimental fishing trials were carried out off the coast of Pernambuco, Brazil, in 1999 and 2001, using a small artisanal longliner. In experiment 1, six-hook baskets with three chemical light-sticks on alternating hooks had significantly higher catch rates than those with zero or with a light-stick on every hook, with most swordfish accounted for by hooks with light-sticks. Analysis of the data from experiment 2 showed no significant difference between electralume attractors, consisting of AA lithium batteries protected by a solid cover and light-sticks that produce a fluorescent light when two chemical products are mixed. Significant differences were detected in mean CPUE by size class, with most swordfish belonging to class ‘b’ (125–170 cm lower jaw to fork length (LJFL)). No differences, however, were found for swordfish catches in classes ‘a’ (<125 cm LJFL) and ‘b’, and no evidence was found of interaction between the two factors (attractor and size class). Although there was no significant difference between the total length-frequency distributions of swordfish caught with light-sticks and electralume attractors, significant differences were found for fish smaller than 125 cm LJFL, with electralume catches consisting of smaller swordfish than those of gear using light-sticks.

Ranakinestatin-PPF from the Skin Secretion of the Fukien Gold-Striped Pond Frog, Pelophylax plancyi fukienensis: A Prototype of a Novel Class of Bradykinin B2 Receptor Antagonist Peptide from Ranid Frogs

The defensive skin secretions of many amphibians are a rich source of bradykinins and bradykinin-related peptides (BRPs). Members of this peptide group are also common components of reptile and arthropod venoms due to their multiple biological functions that include induction of pain, effects on many smooth muscle types, and lowering systemic blood pressure. While most BRPs are bradykinin receptor agonists, some have curiously been found to be exquisite antagonists, such as the maximakinin gene-related peptide, kinestatin—a specific bradykinin B₂-receptor antagonist from the skin of the giant fire-bellied toad, Bombina maxima. Here, we describe the identification, structural and functional characterization of a heptadecapeptide (DYTIRTRLHQGLSRKIV), named ranakinestatin-PPF, from the skin of the Chinese ranid frog, Pelophylax plancyi fukienensis, representing a prototype of a novel class of bradykinin B₂-receptor specific antagonist. Using a preconstricted preparation of rat tail arterial smooth muscle, a single dose of 10⁻⁶ M of the peptide effectively inhibited the dose-dependent relaxation effect of bradykinin between 10⁻¹¹ M and 10⁻⁵ M and subsequently, this effect was pharmacologically-characterized using specific bradykinin B₁- (desArg-HOE140) and B₂-receptor (HOE140) antagonists; the data from which demonstrated that the antagonism of the novel peptide was mediated through B₂-receptors. Ranakinestatin—PPF—thus represents a prototype of an amphibian skin peptide family that functions as a bradykinin B₂-receptor antagonist herein demonstrated using mammalian vascular smooth muscle.

Japanese Encephalitis Virus Utilizes the Canonical Pathway To Activate NF-kappa B but It Utilizes the Type I Interferon Pathway To Induce Major Histocompatibility Complex Class I Expression in Mouse Embryonic Fibroblasts

Flaviviruses have been shown to induce cell surface expression of major histocompatibility complex class I (MHC-I) through the activation of NF-kappa B. Using IKK1(-/-), IKK2(-/-), NEMO-/-, and IKK1-/- IKK2-/- double mutant as well as p50(-/-) RelA(-/-) cRel(-/-) triple mutant mouse embryonic fibroblasts infected with Japanese encephalitis virus (JEV), we show that this flavivirus utilizes the canonical pathway to activate NF-kappa B in an IKK2- and NEMO-, but not IKK1-, dependent manner. NF-kappa B DNA binding activity induced upon virus infection was shown to be composed of RelA: p50 dimers in these fibroblasts. Type I interferon (IFN) production was significantly decreased but not completely abolished upon virus infection in cells defective in NF-kappa B activation. In contrast, induction of classical MHC-I (class 1a) genes and their cell surface expression remained unaffected in these NF-kappa B-defective cells. However, MHC-I induction was impaired in IFNAR(-/-) cells that lack the alpha/beta IFN receptor, indicating a dominant role of type I IFNs but not NF-kappa B for the induction of MHC-I molecules by Japanese encephalitis virus. Our further analysis revealed that the residual type I IFN signaling in NF-kappa B-deficient cells is sufficient to drive MHC-I gene expression upon virus infection in mouse embryonic fibroblasts. However, NF-kappa B could indirectly regulate MHC-I expression, since JEV-induced type I IFN expression was found to be critically dependent on it.

Peptide DV-28 amide: Prototype of a novel class of bradykinin receptor antagonist isolated from the defensive skin secretion of bombinid toads

Kinestatin, isolated from the skin of the Chinese toad, Bombina maxima, was the first bradykinin B2 receptor antagonist identified in amphibians. Molecular cloning established that it is co-encoded with the bradykinin-related peptide, maximakinin, within one of several skin kininogens. To examine other species within the genus Bombina for the presence of structural homologues of kinestatin, we subjected skin secretion of the toad, Bombina orientalis, to HPLC fractionation with subsequent bioassay of fractions for antagonism of bradykinin activity using an isolated rat tail artery smooth muscle preparation. A single fraction was located that inhibited bradykinin-induced relaxation of rat arterial smooth muscle and MALDI-TOF analysis of this fraction revealed that it contained a single peptide of molecular mass 3198.5 Da. Further primary structural analysis of this peptide showed that it was a 28-mer with an N-terminal Asp (D) residue and a C-terminal Val (V) residue that was amidated. The peptide was named DV-28 amide in accordance with these primary structural attributes. Synthetic DV-28 amide replicated the observed bradykinin antagonistic effect within the smooth muscle bioassay in a dose-dependent manner. In addition, it was observed to inhibit the proliferation of human microvessel endothelial cells (HMECs) as assessed by MTT assay. Bioinformatic analysis revealed that DV-28 amide was, like kinestatin, co-encoded with a bradykinin receptor agonist on one of two skin kininogens identified in B. orientalis. DV-28 amide thus represents a novel class of bradykinin antagonist from skin secretions of bombinid toads that appear to be a rich source of such novel peptides.