Microvascularização arterial da cóclea

RESUMO: Na descrição deste estudo foi utilizada a terminologia anatómica da Sociedade Brasileira de Anatomia adaptada ao português por J. A. Esperança-Pina de acordo com o tratado Anatomia Humana da Relação. Os actuais estudos sobre hipoacusia sensorioneural implicam um grupo crescente de situações, em que a lesão se situa ao nível da microvascularização coclear, daí que o conhecimento exacto da angiomorfologia normal se torne essencial na fase actual do conhecimento. A autora tem vindo a estudar, desde 1986, a angiomorfologia do ouvido Interno no modelo experimental, o Cobaio, utilizando várias técnicas microvasculares. sendo dado enfâse particular neste estudo à técnica de microscopia electrónica de varrimento em moldes vasculares. Os animais usados no presente estudo pertencem à espécie cavia porcellus, cobaio, por serem considerados na comunidade cientifica internacional como o melhor modelo experimental para estudo do ouvido interno, pelo facto de a morfologia coclear ser muito semelhante à do Homem e por isso ser um modelo fiável para cirurgia experimental e microdissecção. Este estudo foi realizado em 100 cobaios, cavia porcellus, de ambos os sexos com peso médio de 450g. A vascularização do ouvido interno, no cobaio como no homem, faz-se através dos ramos de divisão da artéria auditiva interna ou labiríntica. A artéria labiríntica origina-se como ramo colateral da artéria cerebelosa ântero-inferior a qual tem origem na artéria basilar ou na artéria vertebral. Embora no homem a artéria auditiva interna possa também destacar-se da artéria basilar e até da artéria vertebral, no cobaio em todos os casos estudados a sua origem verificou-se sempre na artéria cerebelosa ântero-inferior. A artéria labiríntica, ao passar abaixo do meato auditivo interno, divide-se na artéria vestibular anterior e na artéria coclear comum.A artéria vestibular anterior dirige-se para o nervo vestibular, emite vasa nervorum para este nervo e vasculariza o utrículo e os canais semicirculares. A artéria coclear comum origina dois ramos principais, a artéria vestíbulo‑coclear ou vestibular posterior no cobaio, a qual se destaca junto à espira basal da cóclea e a artéria coclear, como ramo terminal, que passa a denominar-se de artéria modiolar ou espiralada, após entrar no modíolo. A artéria modiolar ascende no modíolo promovendo através dos seus ramos colaterais e dos seus ramos terminais a microvascularização coclear, numa vascularização de órgão de tipo terminal. Ao longo do seu trajecto verificou‑se de modo constante uma redução gradual de calibre em cada uma das espiras, por emissão de ramos colaterais, sendo que o calibre da artéria na base da cóclea apresenta um valor que diminui gradualmente até ao ápice. A artéria modiolar origina em todo o seu trajecto ramos colaterais, cujo número diminui em valor absoluto da base para o ápice: Arteríolas radiárias internas, arteríolas de trajecto flexuoso que caminham junto às estruturas sensorioneurais da parede interna da cóclea, junto ao lábio timpânico da lâmina espiral óssea e na parede do próprio modíolo, que se relacionam intimamente com este. As arteríolas radiárias internas originam‑se no flanco da artéria modiolar espiralada. Contam‑se dez a doze em cada espira, extraordinariamente flexuosas desde a sua origem. As arteríolas radiárias internas originam como ramos colaterais, vários grupos de arteríolas de menor calibre, que vascularizam distintas regiões da parede interna da cóclea, as arteríolas do gânglio espiral, a rede espiral interna, as arteríolas de origem dos glomérulos de Schwalbe e a arteríola da lâmina basilar. As arteríolas radiárias externas importantes ramos colaterais da artéria modiolar espiralada promovem a vascularização de importantes estruturas da parede externa. Ao atingir o limite externo do ligamento espiral, as arteríolas radiárias externas dividem‑se em vários ramos arteriolares de menor calibre, ao longo da convexidade do limite externo do ligamento espiral, originando a rede capilar pós-estriada que ocupa a porção lateral do ligamento espiral e a rede capilar ad‑ -estriada, na sua porção mais medial em íntima relação com a estria vascular. A espira basal da cóclea apresenta grande riqueza de vascularização, com características particulares apenas a esta espira, a qual é metabolicamente a mais exigente. A arteríola da janela da cóclea aborda a janela da cóclea pela sua convexidade e divide-se numa rica rede vascular da qual emergem arteríolas pré-capilares que se ramificam em capilares, os quais se dirigem em profundidade penetrando a rampa timpânica da cóclea ao nível da espira basal. Importou neste estudo verificar quais as semelhanças em termos de calibre de estruturas análogas, na parede interna e na parede externa da cóclea, com particular incidência na rede capilar. Do estudo estatístico realizado com testes paramétricos de Tamahane e não paramétricos de Mann-Whitney, verifica-se que comparando todas as estruturas consideradas estas têm calibres diferentes, com excepção dos capilares da estria vascular e do ligamento espiral, pertencentes à parede externa da cóclea que têm calibres iguais aos capilares da rede espiral interna e aos capilares da parede interna da cóclea, dependentes das arteríolas da rede espiral interna. As redes capilares dependentes das arteríolas radiárias internas que vascularizam as estruturas sensorioneurais junto á parede interna do modiolo são em tudo semelhantes em termos de calibre às redes capilares da parede externa da cóclea, incluindo os capilares da estria vascular. Esta particularidade traduz num órgão com vascularização de tipo terminal,um mecanismo de controlo do fluxo sanguíneo coclear tão importante na parede interna como na parede externa da cóclea. ------------ ABSTRACT:Current studies on sensorineural hearing loss, imply a growing group of situations in which the lesion is located at the level of the cochlear microvasculature, hence the exact knowledge of normal angiomorfology becomes essential in current state of knowledge. The author has been studying since 1986, the angiomorfology of inner on the experimental model, the guinea pig, using various microvascular techniques being given particular emphasis in this study to the results of the technique of scanning electron microscopy on corrosion casts. The animals used in this study belong to the species cavia porcellus, guinea pig, to be considered in the international scientific community as the best experimental model for the study of the inner ear, the cochlear morphology is very similar to human and therefore a reliable model for experimental surgery and microdissection. This study was performed in 100 guinea pigs of both sexes with average weight of 450g. There shall be a brief description of embryology, anatomy and cochlear physiology in the light of developmental biology, regarding also the spatial location of the cochlea and the determinism of morphogenetic fields in their development and function. The cochlear transduction mechanism converts the sound wave in stimuli sound and so afferent auditory nerve fibres and deafness are closely related to the cochlear microvasculature. Cochlear ischemia is accompanied by immediate hearing loss. The different type of cochlear injury that leads to sensorineural deafness is well studied in presbycusis where an objective link with the audiometric pattern as been established. The sensory type of deafness, is closely related to the degeneracy of the organ of Corti and damage to the outer hair cells at the basal turn of the cochlea. Keeping in mind cochlear tonotopy with location of high frequency sounds at the level of the base of the cochlea, it explains the audiometric pattern with loss in high frequencies. The neural type of deafness, is characterized by neuronal loss with loss of descendant important neuronal afferents, with audiometric translation on a gradually curve with important loss of auditory discrimination. The metabolic type of deafness results in atrophy of the vascular stria, with consequent change in the potential of the endolymph by decreasing the vascular stria cells and changes in K + recycling mechanism. There is also a change in the morphology of the spiral ligament and the audiometric patern as a flattened curve with loss at all frequencies. Bearing in mind cochlear tonotopy and being characterized all types of sensorineural deafness, we may inquire to what extent the cochlear microvasculature, considering not only the cochlea as a whole but different regions of the inner wall and the outer wall of the cochlea, contributes to deafness. We analysed the entire cochlear morphology on scanning electron microscopy with particular emphasis on bone and membranous cochlea. The inner wall of the cochlea and intramodiolar structures such as the spiral ganglion, the morphology of its cell bodies and their axons are analyzed. The morphology of Corti’s organ is described in detail, with description and large detail of the inner and outer hair cells. Is then presented the study of the microvasculature itself. The spiral modiolar artery is observed with the diaphanization technique and the technique of scanning electron microscopy on corrosion vascular casts. After emergence of collateral branches of the greatest importance, the radiating internal and external arterioles, the modiolar artery gives rise to its terminal branches, the arterioles of the cochear apex. Arterial vasa vasorum and vasa nervorum are displayed with a great detail, which was not yet described in such detail in previous microvascular studies. The arterial radiating arterioles originate in the flank of the spiral modiolar artery in number of ten to twelve in each loop, and they vascularize through their branches the inner wall cochlear sensorineural structures located in the modiolus as the spiral ganglion and structures near the organ of Corti. Their caliber is above 20 μm on the basal turn and in the second loop it decreases to values between 12 and 20 μm, decreasing progressively to the apex of the cochlea.They arise near the modiolus or on their way in the spiral lamina forming vascular loops, and divide without presenting vascular constrictions in their divisions, originating new vascular loops of lower caliber. Internal ratiating arterioles originate as collateral branches several groups of smaller caliber arterioles, which vascularize distinct regions of the inner wall of the cochlea namely, the arterioles of the spiral ganglion, the internal spiral network, the arterioles of origin of the glomeruli of Schwalbe and the arterioles of the basilar membrane. The glomeruli of Schwalbe play an important functional role as relay-stations, in hemodynamic terms, to control the cochlear microvasculature. External radiating arterioles have their origin in the spiral modiolar artery, they are directed towards the outer wall of the cochlea and run through the roof of the scala vestibuli. Above the insertion of Reissner’s membrane on the external wall the external radiating arterioles originate the spiral ligament arterioles, which vascularize the spiral ligament, they divide into several arteriolar branches of smaller caliber, along the convexity of the outer edge of the spiral ligament. The connective tissue of the spiral ligament forms a mesh with supporting function of the highly specialized epithelium, where pericytes were identifiable. Next to its base there is the microvascular network of stria vascularis. The adstriated vascular network which is divided into a capillary network, the capillary network of stria vascularis. The stria vascularis, the only vascularized epithelium of the human body, plays an important role, forming an haemato-labyrintine barrier to assure labyrinthine endocochlear potential and transport of ions, essential for the mechanism of transduction of external hair cells. The cochlear basal turn has a special feature on its external wall, the region of the windows, the round windows giving access to scala tympani and the oval window thatleads into scala vestibuli, and so it is metabolic demanding. For their role in cochlear tonotopy the sensorineural structures and those of the external wall of the cochlea, are particularly vulnerable to hypoxia. Although the complementarity of all the techniques was important for three- -dimensional reconstruction of the microvasculature of the cochlea, the scanning electron microscopy technique, especially when we used the system Semafore was fundamental to perform precise morphometric mesures regarding all vascular structures.Regarding the capillaries of the inner and outer wall of the cochlea networks this technique allowed their characterization in morphometric terms. To conclude the capillaries of the inner wall and of the external wall of the cochlea have similar size. So although located at different cochlear regions, with a different functional role, in cochlear physiology these networks consist of capillaries of similar caliber. It seems to translate a cochlear blood flow control mechanism that is so important in the inner wall as in and the external wall of the cochlea to provide for in inner ear homeosthasia.

Empirical evidence on the difference between the effective and the statutory tax rates for listed groups in Germany

The difference between the statutory and effective tax rate for listed groups is a complex variable influenced by a variety of factors. This paper aims to analyze whether this difference exists for listed groups in the German market and tests which factors have an impact on it. Thus the sample consists of 130 corporations listed in the three major German stock indices. The findings suggest that the companies that pay less than the statutory rate clearly outweigh the ones that pay more, and that the income earned from associated companies has a significant impact on this difference.

Psychological safety, authentic leadership and social networks : A psycho-structural approach to the study of groups

Tese de Doutoramento em Psicologia na área de especialização de Psicologia das Organizações apresentada ao ISPA - Instituto Universitário

Rating corporate groups a modelling experience

This paper aims to provide a model that allows BPI to measure the credit risk, through its rating scale, of the subsidiaries included in the corporate groups who are their clients. This model should be simple enough to be applied in practice, accurate, and must give consistent results in comparison to what have been the ratings given by the bank. The model proposed includes operational, strategic, and financial factors and ends up giving one of three results: no support, partial support, or full support from the holding to the subsidiary, and each of them translates in adjustments in each subsidiary’s credit rating. As it would be expectable, most of the subsidiaries should have the same credit rating of its parent company.

Pratiques comptables des hôpitaux et faisabilité d'un calcul de coûts basés sur les Diagnosis Related Groups

Travaux effectués dans le cadre de l'étude "Case Mix" menée par l'Institut universitaire de médecine sociale et préventive de Lausanne et le Service de la santé publique et de la planification sanitaire du canton de Vaud, en collaboration avec les cantons de Berne, Fribourg, Genève, Jura, Neuchâtel, Soleure, Tessin et Valais

Influence of socioeconomic factors on delays, management and outcome amongst patients with acute myocardial infarction undergoing primary percutaneous coronary intervention.

The outcome after primary percutaneous coronary intervention (pPCI) for ST-elevation myocardial infarction (STEMI) is strongly affected by time delays. In this study, we sought to identify the impact of specific socioeconomic factors on time delays, subsequent STEMI management and outcomes in STEMI patients undergoing pPCI, who came from a well-defined region of the French part of Switzerland. A total of 402 consecutive patients undergoing pPCI for STEMI in a large tertiary hospital were retrospectively studied. Symptom-to-first-medical-contact time was analysed for the following socioeconomic factors: level of education, origin and marital status. Main exclusion criteria were: time delay beyond 12 hours, previous treatment with fibrinolytic agents or patients immediately referred for coronary artery bypass graft surgery. Therefore, 222 patients were finally included. At 1 year, there was no difference in mortality between the different socioeconomic groups. Furthermore, there was no difference in management characteristics between them. Symptom-to-first-medical-contact time was significantly longer for patients with a low level of education, Swiss citizens and unmarried patients, with median differences of 23 minutes, 18 minutes and 13 minutes, respectively (p <0.05). Nevertheless, no difference was found regarding in-hospital management and clinical outcome. This study demonstrates that symptom-to-first-medical-contact time is longer amongst people with a lower educational level, Swiss citizens and unmarried people. Because of the low mortality rate in general, these differences in delays did not affect clinical outcomes. Still, tertiary prevention measures should particularly focus on these vulnerable populations.

Psychometrics of the Dyadic Coping Inventory in three language groups

This article introduces the Dyadic Coping Inventory (DCI; Bodenmann, 2008) and aims (1) to investigate the reliability and aspects of the validity of the Italian and French versions of the DCI, and (2) to replicate its factor structure and reliabilities using a new Swiss German sample. Based on 216 German-, 378 Italian-, and 198 French-speaking participants, the factor structure of the original German inventory was able to be replicated by using principal components analysis in all three groups after excluding two items in the Italian and French versions. The latter were shown to be as reliable as the German version with the exception of the low reliabilities of negative dyadic coping in the French group. Confirmatory factor analyses provided additional support for delegated dyadic coping and evaluation of dyadic coping. Intercorrelations among scales were similar across all three languages groups with a few exceptions. Previous findings could be replicated in all three groups, showing that aspects of dyadic coping were more strongly related to marital quality than to dyadic communication. The use of the dyadic coping scales in the actor-partner interdependence model, the common fate model, and the mutual influence model is discussed.

Impact of relative size and language on the attitudes between nations and linguistic groups : The case of Switzerland

This study explores the impact of relative size on the intra- and intergroup attitudes of groups who either share a language or have a different language. For that purpose, we examined international attitudes, comparing a small nation, Switzerland, and two larger nations, Germany and France. We found support for the assumption that large neighbouring nations pose a threat to the smaller nation's identity, especially when they are linguistically similar. Consequently, in line with Tajfel's Social Identity Theory (1978), the smaller nation's inhabitants evaluate those of the larger nation less positively, liking them less and perceiving them to be more arrogant than vice versa. By investigating the special case of the French-speaking and the German-speaking Swiss as linguistic groups within their own nation we were able to demonstrate that these groups seek support with the larger-linguistically-similar nation to defend themselves against the more direct in-country threat to their identity. They acknowledge the similarity with the larger nation, yet keep defending their social identity by expressing a dislike for this perceived similarity.

Characterizing the vulnerability of frequent emergency department users by applying a conceptual framework: a controlled, cross-sectional study.

BACKGROUND: Frequent emergency department (ED) users meet several of the criteria of vulnerability, but this needs to be further examined taking into consideration all vulnerability's different dimensions. This study aimed to characterize frequent ED users and to define risk factors of frequent ED use within a universal health care coverage system, applying a conceptual framework of vulnerability. METHODS: A controlled, cross-sectional study comparing frequent ED users to a control group of non-frequent users was conducted at the Lausanne University Hospital, Switzerland. Frequent users were defined as patients with five or more visits to the ED in the previous 12 months. The two groups were compared using validated scales for each one of the five dimensions of an innovative conceptual framework: socio-demographic characteristics; somatic, mental, and risk-behavior indicators; and use of health care services. Independent t-tests, Wilcoxon rank-sum tests, Pearson's Chi-squared test and Fisher's exact test were used for the comparison. To examine the -related to vulnerability- risk factors for being a frequent ED user, univariate and multivariate logistic regression models were used. RESULTS: We compared 226 frequent users and 173 controls. Frequent users had more vulnerabilities in all five dimensions of the conceptual framework. They were younger, and more often immigrants from low/middle-income countries or unemployed, had more somatic and psychiatric comorbidities, were more often tobacco users, and had more primary care physician (PCP) visits. The most significant frequent ED use risk factors were a history of more than three hospital admissions in the previous 12 months (adj OR:23.2, 95%CI = 9.1-59.2), the absence of a PCP (adj OR:8.4, 95%CI = 2.1-32.7), living less than 5 km from an ED (adj OR:4.4, 95%CI = 2.1-9.0), and household income lower than USD 2,800/month (adj OR:4.3, 95%CI = 2.0-9.2). CONCLUSIONS: Frequent ED users within a universal health coverage system form a highly vulnerable population, when taking into account all five dimensions of a conceptual framework of vulnerability. The predictive factors identified could be useful in the early detection of future frequent users, in order to address their specific needs and decrease vulnerability, a key priority for health care policy makers. Application of the conceptual framework in future research is warranted.

Collective learning within nursing clinical groups /

This qualitative study examined collective learning within nursing clinical groups. Specifically, it explored the influence of the individual on the group and the impact of the group on the individual. The study was organized using the concepts from Debbie Kilgore's theory of collective learning (1999). The sample consisted of 1 8 second-year university nursing students and 3 clinical instructors. Data were collected via individual interviews with each participant and researcher's observations during a group conference. The interviews were tape-recorded, transcribed, and analyzed using key concepts from Kilgore's framework. Several interesting findings emerged. Overall, it appeared that individual components and group components contributed to the quality and quantity of collective learning that occurred in the groups. Individually, each person's past group experiences, personality, culture, and gender influenced how that individual acted in the group, their roles, and how much influence they had over group decisions. Moreover, the situation which seemed to cause the greatest sense of helplessness and loss of control was when one of their group members was breaking a norm. They were unable to deal with such situations constructively. Also, the amount of sense of worthiness (respect) and sense of agency (control) the member felt within the group had an impact on the person's role in group decisions. Finally, it seemed that students felt more connected with their peers within the clinical setting when they were close with them on a personal and social level. With respect to the group elements, it seemed that the instructors' values and way of being were instrumental in shaping the group's identity. In group 2, there were clear examples of group consciousness and the students' need to go along with the majority viewpoint, even when it was contrary to their own beliefs. Finally, the common goal of passing clinical and dealing with the fears of being in the clinical setting brought solidarity among the group members, and there seemed to be a high level of positive interdependence among them. From the discussion and analysis of the findings, recommendations were given on how to improve the learning within clinical groups.

Exploring the experiences of male spousal caregivers for their wives with alzheimer disease in their homes : the lived experience and the men's perception of support groups /

This research is qualitative in nature and has explored, by means of interviews, the '^^ experiences of 10 men in their roles in caring for their spouses with Alzheimer Disease (see glossary) in their homes. Additional data were collected by attending 3 formal support group meetings and one informal meeting of a group of men who brought their wives to a support group meeting for their wives with AD. The data retrieved supported the assumption that education about the disease, utilization of formal community support services, and attendance at caregiver support groups or programs can assist healthy male caregivers in caring for their wives with AD in their homes.

Graffiti, memory and contested space : mnemonic initiatives following trauma and/or repression in Buenos Aires, Argentina

Graffiti, Memory and Contested Space: Mnemonic Initiatives Following Periods of Trauma and/or Repression in Buenos Aires, Argentina This thesis concerns the popular articulation ofmemory following periods or incidents of trauma in Argentina. I am interested in how groups lay claim to various public spaces in the city and how they convert these spaces into mnemonic battlegrounds. In considering these spaces of trauma and places of memory, I am primarily interested in how graffiti writing (stencils, spray-paint, signatures, etchings, wall-paintings, murals and installations) is used to make these spaces transmit particular memories that impugn official versions of the past. This thesis draws on literatures focused on popular/public memory. Scholars argue that memory is socially constructed and thus actively contested. Marginal initiatives such as graffiti writing challenge the memory projects of the state as well as state projects that are perceived by citizens to be 'inadequate,' 'inappropriate,' and/or as promoting the erasure of memory. Many of these initiatives are a reaction to the proreconciliation and pro-oblivion strategies of previous governments. I outline that the history of silences and impunity, and a longstanding emphasis on reconciliation at the expense of truth and justice has created an environment of vulnerable memory in Argentina. Popular memory entrepreneurs react by aggressively articulating their memories in time and in space. As a result of this intense memory work, the built landscape in Buenos Aires is dotted with mnemonic initiatives that aim to contradict or subvert officially sanctioned memories. I also suggest that memory workers in Argentina persistently and carefially use the sites of trauma as well as key public spaces to ensure official as well as popular audiences . The data for this project was collected in five spaces in Buenos Aires, the Plaza de Mayo, Plaza Congreso, La Republica Cromanon nightclub, Avellaneda Train Station and El Olimpo, a former detention centre from the military dictatorship.

Strategies for economic development in the Commonwealth Caribbean: a comparative study of the foreign economic policy strategies adopted by the Manley government in Jamaica and the Williams government in Trinidad and Tobago

This thesis compares the foreign economic poUcy dimension of the development strategies adopted by the governments of two Commonwealth caribbean countries: The Hardey government In Jamaica, and the· Williams government in Trlnidad and T ooago, The foreign economic policIes adopted by these governments appeared, on the surface~ to be markedly dissimilar. The Jamakan strategv on the one hand, emphasised self-reliance and national autonomy; and featured the espousal of radical oonaHgnment together with attempts to re-deftne the terms of the Islands externaa economIc relaUoos. The Trinidadian strategy 00 the other hand, featured Uberal externaUy-oriented growth poUctes, and close relatjoos with Western governments and financial institutions. Th1s study attempts to identify the explanatory factors that account for the apparent dlssimUarUy 1n the foreign economic policies of these two govemnents. The study is based on a comparison of how the structural bases of an underdeveloped ecooomYg and the foreign penetration and vulnerabUUy to external pressures asSOCiated wUh dependence, shape and influence foreign economic poUcy strategy. The framework views fore1gn ecooom1c strategy as an adaptive response on the part of the decision makers of a state to the coostralnts and opportunities provided by a particular situation. The · situat i 00' in this case being the events, conditions, structures and processes, associated wUh dependente and underdevelopment. The results indicate that the similarities and dissimHarities in the foreign economic policies of the governments of Jamaica and Trinidad were a reflecUon of the simHarities and dissimilarities in their respective situations. The conclusion derived suggests that If the foreign pol1cy field as an arena of choice, Is indeed one of opportunities and constraints for each and every state, then poHcy makers of smaU, weak, hlghW penetrated and vulnerable states enter thlS arena with constraints outweighing opportunities. This places effective limits 00 their decisional latitude and the range of policy options avaUable. Policy makers thus have to decide critical issues with few estabUshed precedents, in the face of domestic social and political cleavages, as wen as serious foreign pressures. This is a reflection not only of the trappings of dependence, but also of the Umned capabilities arising from the sman size of the state, and the Impact of the resource-gap In an underdeveloped economy. The Trinidadian strategy 1s UlustraUve of a development strategy made viable through a combination of a fortuitous circumstance, a confluence of the interests of influential groups» and accurate perception on the part of poUcy makers. These factors enabled policy makers to minimise some of the constraints of dependence. The faUure of Manlets strategy on the other hand, 15 iHustraUve of the problems involved tn the adoption of poUcles that work against the interest of internal and external political and economic forces. It is also tUustraUve of the consequences of the faUure 00 the part of policy makers to clarify goals, and to reconcile the values of rapid economic growth with increased self-reliance and national autonomy. These values tend to be mutuany Incompatible given the existing patterns of relations in the jnternational economy.

Self-presentational motives in eating disorders : a known groups difference approach

Self-presentation reflects the processes by which individuals attempt to monitor and control the impressions others form of them (Schlenker & Leary, 1982). Concerns over impressions conveyed have been linked to numerous health behaviors (Crawford & Eklund, 1994; Martin, Leary, & O'Brien, 2001). The present study investigated the role of cognitive manifestations of dispositional and situational self presentational motivation (SPM) in 131 females with known groups differences on a measure of eating disorders. Participants were classified as in-treatment (IN = 39); at risk (AT = 46); and not at risk (NOT = 46) for eating disordered behaviour. Each participant completed The Brief Fear of Negative Evaluation Scale (FNE; Leary, 1983), the Public Self-Consciousness Scale (PSC; Fenigstein, Sheier, & Buss, 1975), and the Social Physique Anxiety Scale (SPA; Hart, Leary, & Rejeski, 1989), as measures of dispositional SPM. Situational SPM was assessed through Self-Presentational Efficacy (SPE; Gammage, Hall, & Martin, 2004), and the Exercise Motivation Inventory-2 (Markland & Ingeldew, 1997). Significant differences emerged on the measure of eating disorder behaviour between AT and NOT. To determine if group differences existed on measures of trait SPM an ANOVA was conducted. Results indicated that the NOT group experienced less FNE, PSC and SPA than the IN and AT groups, and the AT group experienced less FNE and PSC than the IN group. Pearson bivariate correlations were conducted on measures of trait SPM and EMI-2 subscales theoretically linked to SPM. It was found that FNE, PSC and SPA were all positively correlated with weight management for the NOT group. To determine if group differences existed on selfpresentational exercise motives independent samples I-tests were conducted. Results revealed that the AT group was more motivated to exercise for weight management, and appearance, and social recognition than the NOT group. To determine if group differences existed on the state measure of self-presentational efficacy a series of ANOVA's were conducted. Results revealed that the NOT group experienced significantly greater self-presentational efficacy expectancy and self-presentational outcome value than the AT group. Finally, a discriminant function analysis was conducted to determine if trait SPM would predict group membership. Results revealed that 63.4% of participants were correctly classified, with SPA, PSC, and FNE differentiating the NOT group from the AT and IN groups and FNE and PSC differentiating the AT group from the IN group. Thus self-presentation motivation appears to have an influence on females who have an eating disorder and those at risk for an eating disorder. Potential applications of the influence of self-presentational motives on eating disorders and future research directions are discussed.

Zero-sum problems in finite cyclic groups

The purpose of this thesis is to investigate some open problems in the area of combinatorial number theory referred to as zero-sum theory. A zero-sequence in a finite cyclic group G is said to have the basic property if it is equivalent under group automorphism to one which has sum precisely IGI when this sum is viewed as an integer. This thesis investigates two major problems, the first of which is referred to as the basic pair problem. This problem seeks to determine conditions for which every zero-sequence of a given length in a finite abelian group has the basic property. We resolve an open problem regarding basic pairs in cyclic groups by demonstrating that every sequence of length four in Zp has the basic property, and we conjecture on the complete solution of this problem. The second problem is a 1988 conjecture of Kleitman and Lemke, part of which claims that every sequence of length n in Zn has a subsequence with the basic property. If one considers the special case where n is an odd integer we believe this conjecture to hold true. We verify this is the case for all prime integers less than 40, and all odd integers less than 26. In addition, we resolve the Kleitman-Lemke conjecture for general n in the negative. That is, we demonstrate a sequence in any finite abelian group isomorphic to Z2p (for p ~ 11 a prime) containing no subsequence with the basic property. These results, as well as the results found along the way, contribute to many other problems in zero-sum theory.