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Blood products are essential components of any healthcare system, and their safety, in terms of being free of transfusion-transmittable infections, is crucial. While the Food and Drug Administration (FDA) in the United States requires all blood donations to be tested for a set of infections, it does not dictate which particular tests should be used by blood collection centers. Multiple FDA-licensed blood screening tests are available for each infection, but all screening tests are imperfectly reliable and have different costs. In addition, infection prevalence rates and several donor characteristics are uncertain, while surveillance methods are highly resource- and time-intensive. Therefore, only limited information is available to budget-constrained blood collection centers that need to devise a post-donation blood screening scheme so as to minimize the risk of an infectious donation being released into the blood supply. Our focus is on "robust" screening schemes under limited information. Toward this goal, we consider various objectives, and characterize structural properties of the optimal solutions under each objective. This allows us to gain insight and to develop efficient algorithms. Our research shows that using the proposed optimization-based approaches provides robust solutions with significantly lower expected infection risk compared to other testing schemes that satisfy the FDA requirements. Our findings have important public policy implications. / Ph. D.

Public health screening plays an important role in the overall healthcare system. As an example, consider newborn screening, a state-level initiative that screens newborns for life-threatening genetic disorders for which early treatment can substantially improve health outcomes. Another topical example is in the realm of infectious disease screening, e.g., screening for COVID-19. The common features of both public health screening problems include large testing populations and resource limitations that inhibit screening efforts. Cost is a major barrier to the inclusion of genetic disorders in newborn screening, and thus screening must be both highly accurate and efficient; and for COVID-19, limited testing kits, and other shortages, have been major barriers to screening efforts. Further, for both newborn screening and infectious disease screening, equity (reducing health disparities among different sub-populations) is an important consideration. We study the testing process design for newborn screening for genetic diseases, considering cystic fibrosis as a model disorder. Our optimization-based models take into account disease-related parameters, subject risk factors, test characteristics, parameter uncertainty, and limited testing resources so as to design equitable, accurate, and robust screening processes that classify newborns as positive or negative for cystic fibrosis. Our models explicitly consider the trade-off between false-negatives, which lead to missed diagnoses, and the required testing resources; and the trade-off between the accuracy and equity of screening. We also study the testing process design for infectious disease screening, considering COVID-19 as a model disease. Our optimization-based models account for key subject risk factors that are important to consider, including the likelihood of being disease-positive, and the potential harm that could be averted through testing and the subsequent interventions. Our objectives include the minimization of harm (through detection and mitigation) or maximization of testing coverage. These are complex problems. We develop novel mathematical models and characterize key structural properties of optimal solutions. This, in turn, allows the development of effective and efficient algorithms that exploit these structural properties. These algorithms are either polynomial- or pseudo-polynomial-time algorithms, and are able to solve realistic-sized problems efficiently. Our case studies on cystic fibrosis screening and COVID-19 screening, based on realistic data, underscore the value of the proposed optimization-based approaches for public health screening, compared to current practices. Our findings have important implications for public policy. / Doctor of Philosophy / Public health screening plays an important role in the overall healthcare system. As an example, consider newborn screening, a state-level initiative that screens newborns for life-threatening genetic disorders for which early treatment can substantially improve health outcomes. Another topical example is in the realm of infectious disease screening, e.g., screening for COVID-19. The common features of both public health screening problems include large testing populations and resource limitations that inhibit screening efforts. Cost is a major barrier to the inclusion of genetic disorders in newborn screening, and thus screening must be both highly accurate and efficient; and for COVID-19, limited testing kits, and other shortages, have been major barriers to screening efforts. Further, for both newborn screening and infectious disease screening, equity (reducing health disparities among different sub-populations) is an important consideration. We study the testing process design for newborn screening for genetic diseases, considering cystic fibrosis as a model disorder. Our optimization-based models take into account disease-related parameters, subject risk factors, test characteristics, parameter uncertainty, and limited testing resources so as to design screening processes that classify newborns as positive or negative for cystic fibrosis. Our models explicitly consider the trade-off between false-negatives, which lead to missed diagnoses, and the required testing resources; and the trade-off between the accuracy and equity of screening. We also study the testing process design for infectious disease screening, considering COVID-19 as a model disease. Our optimization-based models account for key subject risk factors that are important to consider, including the likelihood of being disease-positive, and the potential harm that could be averted through testing and the subsequent interventions. Our objectives include the minimization of harm (through detection and mitigation) or maximization of testing coverage. These are complex problems. We develop novel mathematical models and characterize key structural properties of optimal solutions. This, in turn, allows the development of effective and efficient algorithms that exploit these structural properties. Our case studies on cystic fibrosis screening and COVID-19 screening, based on realistic data, underscore the value of the proposed optimization-based approaches for public health screening, compared to current practices. Our findings have important implications for public policy.

In this thesis, two systems are analyzed in order to gain insight to the following issues: (i) Effect of incentive, subsidy and penalty designs on decentralized system, (ii) effect of using production facility as pooled capacity (pooled system) and dedicated capacity (unpooled system) on capacity utilization and system profit. Regarding the first issue, three models are defined / decentralized model, centralized model and decentralized model with incentive, subsidy, penalty designs. In all models, there are two dealers and one item is under consideration and lateral transshipments are allowed. Dealers operate with four inventory level decision (strategies) that consists of base stock level, rationing level, transshipment request level and customer rejection level. Under the decentralized system, a dealer sets its operating strategy according to the strategy of the other dealer and maximizes its own infinite horizon discounted expected profit. In the centralized system, a central authority (say manufacturer) exists, which considers the system-wide infinite horizon discounted expected profit, and makes all decisions. Under decentralized system with incentive, subsidy, penalty designs, manufacturer tries different designs on decentralized system namely revenue sharing, holding cost subsidy, request rejection penalty, transportation cost subsidy and commission subsidy in order to v align decentralized system with centralized system. According to the results obtained, this alignment works best with nearly 40% revenue sharing percentage, low rejection penalty, high transportation cost subsidy under low transportation cost and commission subsidy under very low or very high commissions. Holding cost subsidy, on the other hand, is not a good strategy since it declines decentralized system profit. Considering the second issue, two systems are examined / pooled system and unpooled system. Both systems are centrally managed. In the pooled system, all capacity is dynamically allocated to either dealer considering maximization of system profit. In the unpooled system, capacity is shared among dealers and dealers are always allocated same percentage of the capacity. Infinite horizon average expected profit is maximized in both systems. The dealer having lower holding cost is allocated higher capacity in both pooled and unpooled system / however, exceptions exist in the unpooled system under low arrival rate. Highrevenue dealer is always allocated higher capacity in both pooled and unpooled system. Arrival rate affects both systems such that total capacity utilization increases with increasing arrival rate. From the profit point of view, pooled system has great advantage under low demand rate in general.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 47 pages. / Thesis (M.A.)--University of South Florida, 2002. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: This thesis analyzes the policy effects of several state gun control restrictions in the United States. The study employs the data of gun related crimes and gun control restrictions from Statistical Abstract of Criminal Justice Handbook through five years (from 1995 to 2000). Although many scholars have studied previously gun control policy effects on crimes, they always focus on the total violence level and ignore to compare the policy effects of different gun control laws. The present study examines intensively gun related crimes and compares several gun control policies. Pooled data is employed to access the effects of gun control restrictions, and it is another advancement based on previous studies, which always use cross-sectional or time series designs. / ABSTRACT: These findings partially reject the previous conclusions that gun control laws have no effects on violence and for gun related homicides and robberies; several gun control restrictions like registration, license, and waiting period show some significant policy effects. Contrary to the past study, the permit to purchase, which has been regarded as the most efficient law, produces no significant policy effects. Sale report to police and certain firearm prohibited also have no significant effects. Among control variables, race and urban population exert the obvious influences on the gun violence, and specifically, the density of population affects the gun related homicides and high school graduates affects the gun related robberies. Implications of these findings and potential for future research are discussed. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

The transnational traffic of narcotics has had undeniable impacts on international development, for instance, stagnant economic growth in Myanmar (Chin, 2009), unsustainable agricultural practices in Yemen (Robins, 2016), and human security threats in Columbia (Thoumi, 2013). Furthermore, globalization is a catalyst for the transnational narcotics traffic (Robins, 2016; Aas, 2007; Kelly, Maghan & Serio, 2005). Several qualitative studies exist on the transnational narcotics traffic, yet few quantitative studies examine the issue. There is thus an opportunity for novel quantitative studies on the general question: “what are the main economic factors that influence the transnational traffic of narcotics between countries?” This study looked at the specific question: “are distance and economic size correlated with the volume of narcotics traffic between countries?” This study chose the gravity model as it centres on bilateral trade (Tinbergen, 1962), accounts for trade barriers (Kalirajan, 2008) and is empirically robust (Anderson 2011). This study defined a basic functional gravity model relating a proxy of the narcotics traffic to distance and economic size. Four augmented functional gravity models were also advanced to address omitted variable bias. The research was limited conceptually to cross sectional and pooled time series data. In addition, the data was also limited practically to a convenience sample of secondary data drawn from: the United Nations Office on Drugs and Crime’s (UNODC) (2016a) Individual Drug Seizures (IDS); the World Bank’s (2016) World Development Indicators; and the CEPII’s GeoDist (2016) datasets. This study used a novel “dosage” approach to unit standardization to overcome the challenge posed by the many measures and forms of narcotics. The study used the Poisson pseudo maximum likelihood (PPML) estimator as its estimations of the gravity model are consistent (Gourieroux et al., 1984), allow heteroscedasticity (Silva & Tenreyro, 2006) and avoid back transformation bias (Cox et al., 2008). The evidence analyzed in this study seem to indicate that the gravity model may not be applicable in its current form to the transnational narcotics traffic among countries that report drug seizures to the UNODC. However, the sampling method and the choice of proxy are likely to influence these findings. Moreover, the low explanatory power of the gravity model for the narcotics traffic, reflected in the values of the pseudo-R-squared coefficient of determination, indicates that other factors are at play. For instance, authors such as Asad and Harris (2003) and Thoumi (2003) argue that institutions could be a key factor in the narcotics traffic. Future empirical research into this topic could build on the theses findings to introduce new proxies and to explore alternate theoretical frameworks.

Life history traits affect the timing and pattern of maturation, reproduction, and survival during an organism’s lifecycle and are the major components influencing Darwinian fitness. Co-evolved patterns of these traits are known as life history strategies (LHS) and variation occurs between individuals, populations, and species. The polymorphisms underlying LHS are important targets of natural selection, yet the underlying genes and physiological mechanisms remain largely unknown. Mapping the genetic basis of a LHS and subsequently unraveling the associated physiological mechanisms is a challenging task, as complex phenotypes are often polygenic. However, in several systems discrete LHS are maintained within the population and are inherited as a single locus with pleiotropic effects. These systems provide a promising starting point for investigation into LHS mechanisms and this thesis focuses on one such strategy - the Alba polymorphism in Colias butterflies. Alba is inherited as a single autosomal locus, expressed only in females, and simultaneously affects development rate, reproductive potential, and wing color. Alba females are white, while the alternative morph is yellow/orange. About 28 of 90 species exhibit polymorphic females, though whether the Alba mechanism and associated tradeoffs are conserved across the genus remains to be determined. In this thesis I primarily focus on the species Colias croceus and integrate results from lipidomics, transcriptomics, microscopy, and genomics to gain insights to the proximate mechanisms underlying Alba and Alba’s evolution within the genus. Lipidomics confirm that, consistent with findings in New World species, C. croceus Alba females have larger abdominal lipid stores than orange, an advantage which is temperature dependent and arises primarily due to mobilized lipids. Gene expression data suggests differences in resource allocation, with Alba females investing in reproduction rather than wing color, consistent with previous findings in other Colias species. Additionally, I identify a morphological basis for Alba’s white wing color. Alba females from C. croceus, an Old World species, and Colias eurytheme, a New World species both exhibit a significant reduction in pigment granules, the structures within the wing scale that contain pigment. This is a trait that seems to be unique to Colias as other white Pierid butterflies have an abundance of pigment granules, similar to orange females. I also map the genetic basis of Alba to a single genomic region containing an Alba specific, Jockey-like transposable element insertion. Interestingly this transposable element​ is located downstream of BarH-1, a gene known to affect pigment granule formation in Drosophila. Finally, I construct a phylogeny using a global distribution of 20 Colias species to facilitate investigations of Alba’s evolution within the genus. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.</p>

La violence contre les policiers a des répercussions importantes à la fois chez les policiers et pour les administrateurs de la police. En 2005, le taux canadien de voies de fait contre la police a atteint son plus haut sommet en plusieurs décennies, faisant état d’une situation préoccupante. Plusieurs provinces canadiennes connaissent d’ailleurs une hausse marquée de la violence contre leurs policiers depuis plusieurs années. Cette étude vise donc à examiner et à comprendre l’évolution du phénomène de violence contre les policiers au Canada par l’identification de facteurs qui pourraient expliquer les variations du taux de voies de fait contre les policiers. La méthode d’analyse privilégiée dans le cadre de cette étude est une analyse transversale de séries chronologiques regroupées (pooled time series) qui traite des données portant sur les dix provinces canadiennes pour une période allant de 1986 à 2006. Les résultats indiquent que plusieurs facteurs ont un impact sur la violence dont sont victimes les policiers : la proportion de la population âgée entre 15 et 24 ans, la proportion d’hommes de 15 ans et plus, la proportion de la population vivant dans une région urbaine, la proportion de gens divorcés, les taux résiduels de crimes de violence et de crimes rattachés aux drogues, et le nombre d’évasions et de personnes en liberté sans excuse. La présence croissante de policières, qui fait encore l’objet de débats, semble quant à elle réduire le nombre de voies de fait contre la police, quoique l’impact de ce facteur soit de faible portée. Au Québec, la une hausse importante du taux de voies de fait contre les policiers pourrait s’expliquer par la hausse de plusieurs facteurs identifiés comme jouant un rôle dans le phénomène, bien qu’il ne faille pas écarter qu’un changement dans la reportabilité puisse entrer en ligne de compte. / Violence against police officers has important implications both for police officers and police administration. In 2005, the Canadian rate of assault against police officers rose to its highest in decades, showing a worrying situation. Moreover, several Canadian provinces are experiencing a marked increase in violence against their police officers for several years. This study aims to examine and understand the trend of violence against the police officers in Canada by identifying factors affecting the rate of assaults against police officers. In order to do so, a pooled time series analysis, which processes data on the ten Canadian provinces for the period from 1986 to 2006, was performed. Findings indicate that several factors have an impact on the violence against the police: the proportion of young people aged 15-24, the proportion of males aged 15 and more, the proportion of population living in urban areas, the proportion of divorced people, the residual rates of violent crimes and drug crimes, and the number of people who escaped custody and prisoners unlawfully at large. The growing presence of women police officers, which is still debated, appears to reduce the number of assaults against police officers, although the impact of this factor is of limited scope. In Quebec, the continual increase in the rate of assaults against the police officers can possibly be explained by the increase of several factors identified as playing a role in the phenomenon, although a change in crime reporting can also be taken into account.

Le cancer du poumon chez la femme était une maladie rare au début du XXème siècle. Son incidence a fortement augmenté durant ces vingt dernières années dans les pays développés et particulièrement en France du fait de l’augmentation de la consommation de cigarettes dans la population féminine. L’étude des risques de cancer du poumon liés à la consommation de cigarettes des femmes a soulevé la question d’une éventuelle plus grande susceptibilité des femmes vis-à-vis du tabac dans la survenue du cancer du poumon par rapport aux hommes. Les résultats des études épidémiologiques sur le sujet sont divergents et l’hypothèse selon laquelle les hormones joueraient un rôle dans cette plus grande susceptibilité des femmes a été proposée pour expliquer ces différences. Objectifs : Les objectifs de cette thèse sont de donner des estimations récentes du risque de cancer du poumon chez la femme associé à la consommation de cigarettes en France, de comparer le risque de cancer du poumon chez les femmes et chez les hommes et d’étudier le rôle des hormones dans le risque de cancer du poumon.Matériel et méthodes : L’étude de la consommation de cigarettes chez les femmes et la comparaison des risques de cancer du poumon associé à cette consommation a été réalisée à partir des données de l’étude ICARE. Les cas de cancer du poumon ont été identifiés dans 10 départements incluant un registre général de cancer. Au total, 2276 cas de cancer du poumon chez les hommes et 2780 témoins ont été inclus ainsi que 650 cas de cancers du poumon féminins et 775 témoins. Les témoins étaient issus de la population générale, avec une distribution âge et sexe conforme à celle des cas et une répartition par statut socioéconomique conforme à celle des départements dont sont issus les cas. L’analyse du rôle des hormones et des facteurs reproductifs sur le risque du cancer du poumon a été menée par une analyse poolée, réunissant 9 études internationales. Cette étude a été réalisée dans le cadre du consortium ILCCO. Au total, 4547 cas et 4176 témoins ont été inclus dans l’analyse.Résultats : Notre étude a montré que le risque de cancer du poumon associé à la consommation de cigarettes est 8 fois plus élevé chez les femmes fumeuses par rapport aux non fumeuses en France. La quantité moyenne fumée, la durée totale de consommation et le délai depuis l’arrêt sont les 3 principales caractéristiques de consommation qui modulent le risque de cancer du poumon. La fraction de risque attribuable à la consommation de cigarettes est estimée à 55% [47 %-63 %]. La comparaison du risque de cancer du poumon entre les hommes et les femmes est très influencée par la présence des non fumeurs. . Bien que nous n’ayons pas trouvé de différence de risque de cancer du poumon entre les hommes et les femmes fumeurs lorsque l’on considère tous les types histologiques réunis, nous avons constaté que les femmes relativement aux hommes étaient plus à risque de cancer à petites cellules et de cancer épidermoïde, qui sont les types histologiques les plus liés à la consommation de cigarettes. Concernant l’étude sur le rôle des hormones dans la survenue de cancer du poumon, nos résultats montrent que plus l’âge à la ménopause est tardif et plus la durée des cycles menstruels est longue, moins le risque de cancer du poumon est important. Nous avons également montré que l’ovariectomie était associée positivement avec le risque de cancer du poumon. Conclusion : Nos résultats semblent indiquer que les femmes fumeuses sont peut-être plus à risque de développer un carcinome à petites cellules ou un cancer épidermoïde par rapport aux hommes fumeurs. L’étude sur les facteurs hormonaux a montré une association négative avec l’exposition prolongée aux hormones, qui n’est pas très cohérente avec un risque de cancer du poumon associé au tabac plus important chez les femmes que chez les hommes. / The incidence of female lung cancer in developed countries has been increasing since 1950 and particularly in France where the cigarettes consumption has also increased. Since 1980, a growing number of epidemiological surveys have pinpointed the risk of female lung cancer related to smoking. Consecutively, a debate on gender differences in lung cancer risk has appeared, but still in progress nowadays. The reproductive factors could explain these differences. In order to have recent and reliable data on the association between cigarettes smoking and the risk of lung cancer in women and to compare the lung cancer risk associated with smoking exposure between genders, we analyzed the data of a French population-based case-control study, ICARE. The role of the reproductive factors in lung cancer was analyzed pooling, 9 international epidemiological studies included in ILCCO consortium.The ICARE study included 2276 male and 650 female cases and 2780 male and 775 female controls. Lifetime smoking exposure was represented by the comprehensive smoking index (CSI) which combines total duration of smoking, the mean intensity and the time since cessation. The pooled analysis of the reproductive factors included a total of 4547 cases and 4176 controls were included.Among the ever smokers, the relative risk of lung cancer was similar among men and women after adjustments for age, département, education, BMI, occupational exposure and chronic bronchitis. However, we found that women have a 2-fold greater risk than men of developing either small cell carcinomas or squamous cell carcinomas. Alternatively, the association was similar between men and women for the adenocarcinomas. As regard the reproductive factors, we found that longer is the age at menopause, lower is the lung cancer risk. Moreover, longer is the duration of cycle, lower is the lung cancer risk. The ovariectomy is also associated with an increasing risk of lung cancer.Our findings suggest that women might be more susceptible than men to develop small cell carcinoma or squamous cell carcinoma in response to the carcinogenic effect of cigarettes smoking. The analysis on the reproductive factors showed an inverse association between hormonal exposure and lung cancer indicating a likely complex relationship between the two factors.

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2014-09-17T21:01:01Z No. of bitstreams: 2 José Neiva Mesquita Neto.pdf: 2799737 bytes, checksum: 590e98d41066ac6babc47eeb04637796 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Rejected by Luciana Ferreira (lucgeral@gmail.com), reason: Marlene, olhe nas orientações a questão da citação, a qual deve ser de acordo com a NBR 6023: ALCÂNTARA, Guizelle Aparecida de. Caracterização farmacognostica e atividade antimicrobiana da folha e casca do caule da myrciarostratadc.(myrtaceae). 2012. 41 f. Dissertação (Mestrado em Ciências Farmacêuticas) - Universidade Federal de Goiás, Goiânia, 2012. on 2014-09-18T12:33:01Z (GMT) / Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2014-09-18T19:01:02Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) José Neiva Mesquita Neto.pdf: 2799737 bytes, checksum: 590e98d41066ac6babc47eeb04637796 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-09-19T11:32:20Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) José Neiva Mesquita Neto.pdf: 2799737 bytes, checksum: 590e98d41066ac6babc47eeb04637796 (MD5) / Made available in DSpace on 2014-09-19T11:32:20Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) José Neiva Mesquita Neto.pdf: 2799737 bytes, checksum: 590e98d41066ac6babc47eeb04637796 (MD5) Previous issue date: 2013-09-19 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Plant-pollinator interactions in syncronopatric species of Psychotria (Rubiaceae). Psychotria species are commonly found in the understory of forested areas in tropical regions, and are important components for the functioning of these ecosystems. Many species of the genus are sympatric and bloom during the same period, being considered potentially syncronopatrics. For this reason, this genus has been considered as a good model to infer general patterns and mechanisms of speciation in the tropics. In the first paper of this dissertation, the interactions between potentially sympatric species of Psychotria and their pollinators were analyzed in order to verify the possible existence of sharing, specialization or generalization of pollinators and plants in the analyzed system. Then, data of secondary studies that contained identifying pollinators of Psychotria were analyzed From these data, we generated graphs and analyzes of interaction networks and niche overlap. Altogether, nine species of Psychotria and 25 species of pollinators of occurrence in the Atlantic Forest were included in the analyzes. The plant with the most generalist network is Psychotria tenuinervis and the pollinators with the highest proportion of links and consequently with more important role in the network belonged orders Lepidoptera and Hymenoptera. Psychotria species showed niche overlap in pollination and pollinator sharing. The period of greatest intensity of flowering coincided with the rainy season in the Atlantic Forest, with up to seven species coflowering. Because Psychotria species occur in sympatry and have flowering overlap and asymmetric interactions with flower visitors, it is possible that they are involved in a process of facilitation in pollination. The second paper aimed to investigate if four sympatric populations of Psychotria show pollinators sharing and pollination niche overlap . Another objective was to determine if their flowering season are synchronics. We found a dual synchrony in this system, the first in the intensity of flowering among the populations of Psychotria and the second in the increase of the abundance of flowers and pollinators. The species of Psychotria showed sharing fundamental niche of pollination and positive impact on reproductive success. However, we note that the sharing of pollinators can not be generalized to the entire system, but to the modules or pairs of species. Thus, each species of Psychotria has one or more species of preferential pollinator for sharing and that this relationship is not always reciprocal. This reinforces that the interactions among the plant species are asymmetric. / Interação planta-polinizador em espécies sincronopátricas de Psychotria (Rubiaceae). Psychotria contribui de forma importante para a diversidade florística tropical e são comumente encontradas em sub-bosque de áreas florestadas em regiões tropicais, sendo importantes componentes para o funcionamento destes ecossistemas. Muitas espécies do gênero são simpátricas e florescem em um mesmo período do ano, sendo consideradas potencialmente sincronopátricas. Por esta razão, este gênero tem sido considerado como um bom modelo para inferir padrões e mecanismos gerais de especiação nos trópicos. No primeiro artigo, as interações entre espécies potencialmente simpátricas de Psychotria e seus polinizadores foram analisadas com o objetivo de verificar a possível existência de partilha, de especialização ou generalização de polinizadores e plantas no sistema analisado. Para isso, foram incluídas informações secundárias de estudos que continham a identificação em nível de espécie de polinizadores de Psychotria. A partir desses dados, foram gerados grafos e realizadas análises de redes de interação e sobreposição de nicho. Ao todo, foram incluídas nas análises nove espécies de Psychotria com registro de ocorrência para a Mata Atlântica, sendo que elas interagiram com 25 espécies de polinizadores. A planta mais generalista da rede foi Psychotria tenuinervis e os polinizadores que concentraram maior número de links e consequentemente com papel mais importante na rede pertenceram as ordens Lepidoptera e Hymenoptera. As espécies de Psychotria apresentaram sobreposição de nicho na polinização com partilha de polinizadores. O período de maior intensidade de floração coincidiu com o período chuvoso na Mata Atlântica, com até sete espécies apresentando coflorescimento. Assim, pode-se inferir que a polinização em Psychotria demanda polinizadores generalistas. Pelo fato das espécies de Psychotria ocorrerem em simpatria, possuírem floração sobreposta e interações assimétricas com visitantes florais, é possível que estejam envolvidas em um processo de facilitação na polinização. Já o segundo artigo objetivou averiguar se quatro populações simpátricas de Psychotria, em cofloração, apresentaram partilha de polinizadores e sobreposição de nicho na polinização. Além disso, objetivou verificar se existe sincronia entre as populações vegetais e destas com comunidade de polinizadores. Foi encontrada uma dupla sincronia nesse sistema, sendo a primeira na intensidade de floração entres as populações de Psychotria e a segunda no aumento da abundância de flores e de polinizadores. As espécies de Psychotria apresentaram partilha fundamental do nicho da polinização e com reflexo positivo no sucesso reprodutivo. No entanto, verificamos que a partilha de polinizadores não pode ser generalizada a todo o sistema, mas sim a módulos ou pares de espécies. Dessa forma, cada espécie de Psychotria possui uma ou mais espécies preferencias para partilha de polinizadores e que nem sempre essa relação é reciproca. Isso reforça que as interações entre as plantas são assimétricas.