Este trabalho apresenta uma contribuição ao estudo das flutuações quânticas dos feixes sonda e de bombeio na condição de transparência induzida por laser. Com esse estudo conseguimos observar nas flutuações dos campos uma manifestação do caráter coerente da interação dos átomos com os feixes. Para alcançar nosso objetivo, derivamos a teoria do fenômeno da transparência induzida tratando ambos feixes dentro do formalismo quântico. Com tal formulação, encontramos que a condição de transparência induzida corresponde a um estado de equilíbrio dinâmico do sistema átomo - campo de bombeio - campo sonda onde, os átomos redistribuem os fótons entre os campos, correlacionando os mesmos e alterando, ao mesmo tempo, as propriedades estatísticas desses feixes. Utilizando dois critérios diferentes, mostrando que a correlação entre os feixes sonda e de bombeio é de natureza quântica, o que possibilita a aplicação desse sistema, por exemplo, na informação e computação quânticas. Os resultados experimentais obtidos confirmaram as previsões teóricas em relação às flutuações quânticas dos campos, e a existência de uma correlação entre eles. Trata-se da primeira investigação experimental de propriedades estatísticas dos campos em transparência induzida. A correlação de intensidade medida é o primeiro passo para a observação de emaranhamento entre feixes sonda e de bombeio na condiçào de transparência induzida. / In this work we presente a contribution to the study of quantum fluctuations of pump and probe filds in the Electromagnetically Induced Transparency (EIT) condition. We observed in the fields fluctuations evidence of the coherent character of the interaction between the atoms and the fields. To reach our purpose, the fields were treated quantum-mechanically in deriving the theory of the EIT phenomenon. Using this formulation, we concluded that the EIT condition corresponds to a state of dynamical equilibrium of the system atom pump field probe field, where the atoms redistribute the photons between both fields, correlating them and, at the same time, affecting their statistical properties. By means of two different criteria we showed that such a correlation is of quantum nature, making possible the application of this system in, for example, quantum information and quantum computation. The theoretical predictions were corroborated by our experimental results regarding the quantum fluctuations and the existence of a correlation between the pump and probe fields. This is the first experiment to investigate statistical properties of the fields in EIT. The intensity correlation measured is the first step towards the observation of entanglement between the fields.

Coefficient of Pearson r is used to compare scientific tests. In seeds technology it is used to compare results of procedures that measure vigour. When the correspondly similar results are not found in very similar conditions, Person s correlation faces criticism mainly due to two factors. The first one comes from statistics for whose usage of Person s correlation there are prescriptions that are not always observed, when they are not understood as assumption. Variables naturally associated are required with bivariated normal distribution, pairing; homoscedasticity, rectilinear dispersion; detection of outliers. Added to them, there are practical observations in what refers the correlation to be valid only in a restrict range of the data series, the necessity to create value ranges to consider this correlation as good or bad , the need of the graphical analysis, the use and interpretation of the significance, among others. The second cause of odd results would be the existence of several biological factors, which are sometimes support for the reserarcher conclusions. With the objective of identifying applicability of correlations and the causes for odd results of r, there have been compared data existent in the Seeds Analysis Laboratory of ICIAG of the Universidade Federal de Uberlândia-MG, as well as tests of germination of acelerated aging in optimal conditions of repetibility done in laboratory, and tests of field seedling emergency, as well as other simulated variables. The results showed odd results. The normal scattergram between X and Y is enough clear to elucidate only correlated variables of large samples. Although, if the covariance is not as obvious the dispersion Y=f(X) is not enough to show simultaneous increasing or decreasing between variables. With an alternative methodology of plotting the variables related to another auxiliar variable Z of the same n elements of X and Y, we could study the variable behavior in an individual way. It was possible to create graphic criteria to assess non-valid correlations, such as similarity of variables comparable to homoscedastity; influence of outliers on small or big n; grouping of outliers in a dissident range , influence of treatments effect. In the analysed cases, we concluded that, comparing seeds vigour with only laboratory results, as well as its relation with the field results and among simulated data, the results inconsistency of correlations are prevalent as they do not follow the literature prescriptions, among others. The magnitude of the distortions due to statistical causes did not leave space for measuring effects of the variation of the biological seeds conditions, temporal alterations related to management or the edafoclimatic ones. Keywords: 1. Failure in correlations 2. Correlation reliability / Coeficiente de Pearson r é usado para comparar experimentos científicos. Em tecnologias de sementes serve para comparar resultados de procedimentos que medem vigor. Quando se prognosticam resultados de correlações baseados em condições similares e eles não acontecem, a correlação de Pearson enfrenta críticas, atribuídas principalmente a duas causas. Primeiramente pela estatística, para cuja utilização da correlação de Pearson existem prescrições nem sempre observadas, talvez por não serem entendidas como pressuposições. Exigem-se variáveis métricas naturalmente associadas, com distribuição normal bivariada, pareamento, homoscedasticidade, nuvem de dispersão retilínea; detectção de outliers. Somam-se observações práticas quanto à validade restrita a um trecho da série de dados, da criação de faixas de valores para considerá-la de baixa a alta , da necessidade da análise gráfica, da interpretação de significância, entre outras. A segunda causa seria justamente a existência de variação biológica devido a fatores diversos externos e interno às sementes, servindo às vezes de sustentáculo para conclusões de interesse do pesquisador. No objetivo de identificar aplicabilidade das correlações e as causas de resultados estranhos, foram comparados dados existentes no Laboratório de Análises de Sementes do ICIAG da Universidade Federal de Uberlândia-MG, testes germinação de envelhecimento acelerado em condições ideais de repetibilidade em laboratório, e teste de emergência de plântulas em campo, e outras variáveis simuladas, havendo incidência de resultados estranhos. A representação gráfica normal da dispersão entre X e Y mostra satisfatoriamente o correlacionamento de variáveis naturalmente associadas com n grande. Entretanto, se a covariância não é tão óbvia, a disperção Y=f(X) não é suficiente para mostrar crescimento ou decréscimo simultâneo entre as variáveis. Usando metodologia alternativa de plotagem das variáveis em relação a uma variável auxiliar Z, de mesmos n elementos que X e Y, pôde-se estudar individualmente o comportamento das variáveis. O método gráfico permitiu taxar correlações em válidas ou não pela similaridade das variáveis, comparável à homoscedasticidade; verificar outliers em n pequeno ou grande; agrupamento de outliers em trecho dissidente e mostrar efeito de tratamentos. Nos casos analisados, concluiu-se que, comparando vigor de sementes com resultados só de laboratório, tão bem como no seu relacionamento com os de campo; e entre dados simulados, as inconsistências de resultados de correlações são preponderantes por não seguirem as prescrições da literatura, entre outras. A magnitude das distorções por causas estatísticas não deixou espaço para mensurar efeitos da variação de condições biológicas de sementes, alterações temporais relativas a manuseio ou edafoclimáticas. / Mestre em Agronomia

Este trabalho apresenta uma contribuição ao estudo das flutuações quânticas dos feixes sonda e de bombeio na condição de transparência induzida por laser. Com esse estudo conseguimos observar nas flutuações dos campos uma manifestação do caráter coerente da interação dos átomos com os feixes. Para alcançar nosso objetivo, derivamos a teoria do fenômeno da transparência induzida tratando ambos feixes dentro do formalismo quântico. Com tal formulação, encontramos que a condição de transparência induzida corresponde a um estado de equilíbrio dinâmico do sistema átomo - campo de bombeio - campo sonda onde, os átomos redistribuem os fótons entre os campos, correlacionando os mesmos e alterando, ao mesmo tempo, as propriedades estatísticas desses feixes. Utilizando dois critérios diferentes, mostrando que a correlação entre os feixes sonda e de bombeio é de natureza quântica, o que possibilita a aplicação desse sistema, por exemplo, na informação e computação quânticas. Os resultados experimentais obtidos confirmaram as previsões teóricas em relação às flutuações quânticas dos campos, e a existência de uma correlação entre eles. Trata-se da primeira investigação experimental de propriedades estatísticas dos campos em transparência induzida. A correlação de intensidade medida é o primeiro passo para a observação de emaranhamento entre feixes sonda e de bombeio na condiçào de transparência induzida. / In this work we presente a contribution to the study of quantum fluctuations of pump and probe filds in the Electromagnetically Induced Transparency (EIT) condition. We observed in the fields fluctuations evidence of the coherent character of the interaction between the atoms and the fields. To reach our purpose, the fields were treated quantum-mechanically in deriving the theory of the EIT phenomenon. Using this formulation, we concluded that the EIT condition corresponds to a state of dynamical equilibrium of the system atom pump field probe field, where the atoms redistribute the photons between both fields, correlating them and, at the same time, affecting their statistical properties. By means of two different criteria we showed that such a correlation is of quantum nature, making possible the application of this system in, for example, quantum information and quantum computation. The theoretical predictions were corroborated by our experimental results regarding the quantum fluctuations and the existence of a correlation between the pump and probe fields. This is the first experiment to investigate statistical properties of the fields in EIT. The intensity correlation measured is the first step towards the observation of entanglement between the fields.

La notion de cohérence, intimement liée à celle de dualité onde-corpuscule, joue un rôle central en mécanique quantique. Lorsque la cohérence quantique s'étend sur plusieurs particules au sein d'un système, la description en termes d'objets individuels devient impossible en raison des corrélations quantiques (ou intrication) qui se développent. Dans ce manuscrit, nous étudions les systèmes à l'équilibre, pour lesquels nous montrons que les fluctuations cohérentes viennent s'ajouter aux fluctuations prédites par des identités thermodynamiques valides pour les systèmes classiques. Au zéro absolu, les fluctuations cohérentes sont les seules à subsister, et nous étudions dans ce cas leur lien avec l'entropie d'intrication. Nous montrons en particulier qu'une hypothèse de température effective modulée spatialement rend compte de la structure de l'intrication au sein d'un système à N corps, et montrons comment cette température peut être extraite des corrélations usuelles. Nos résultats permettent par ailleurs une compréhension affinée des transitions de phase quantiques. Nous montrons par exemple que la transition entre un isolant de Mott bosonique et un superfluide donne lieu à une singularité de l'entropie d'intrication induite par les fluctuations d'amplitude de la phase du condensat. Nous identifions enfin une longueur de corrélation pilotant les lois d'échelles des fluctuations cohérentes au sein de l'éventail critique avoisinant une transition de phase quantique du second ordre, et proposons une ouverture vers les potentielles applications métrologiques de ces fluctuations cohérentes exceptionnellement fortes en nous appuyant sur l'exemple du modèle d'Ising. / The notion of coherence, intimately related to the notion of wave-particle duality, plays a central role in quantum mechanics. When quantum coherence extends over several particles inside a system, the description in terms of individual objects becomes impossible, due to the development of quantum correlations (or entanglement). In this manuscript, we focus on equilibrium systems, for which we show that coherent fluctuations add up to the fluctuations predicted by thermodynamic identities, valid for classical systems only. In the ground state, coherent fluctuations are the only ones to subsist, an in this case we study their relationship with entanglement entropy. We show in particular that an hypothesis of effective temperature, spatially modulated, captures the structure of entanglement in a many-body system, and we show how this temperature can be reconstructed from usual correlation functions. Our results also enable for a refined understanding of quantum phase transitions. We show in particular that the phase transition between a bosonic Mott insulator and a superfluid gives rise to a singularity of entanglement entropy induced by amplitude fluctuations of the phase of the condensate. We finally identify a coherence length governing the scaling behaviour of coherent fluctuations inside the quantum critical region in the finite-temperature vicinity of a quantum critical point, and open novel perspectives for the metrological advantage offered by the exceptional coherence which develops close to quantum critical points, based on the example of the quantum Ising model.

Contexte : La chromodynamique quantique (CDQ), théorie de l’interaction forte, prédit un nouvel état de la matière, le plasma de quarks et de gluons (PQG) dont les degrés de liberté fondamentale, les quarks et les gluons, peuvent bouger quasi-librement. Les hautes températures et densités de particules, qui sont nécessaires, sont supposées être les conditions de l’univers dans ses premiers moments ou dans les étoiles à neutrons. Récemment elles ont été recrées par des collisions de noyaux d’ions lourdes à hautes énergies. Ces expériences étudient le PQG par la détection des particules de hautes énergies qui traversent le milieu, notamment, les quarks lourds. Les mécanismes de leur perte d’énergie dans le PQG ne sont pas compris complètement. Particulièrement, ils sont attribués aux processus soit de radiation induite par le milieu, soit de collisions de particules de type 2 vers 2, ou des combinaisons.Méthodes : Afin de trouver de nouvelles observables pour pouvoir distinguer les mécanismes de la perte d’énergie, on a implémenté un algorithme Monte-Carlo, qui simule la formation des cascades des particules à partir d’une particule initiale. Pour traiter le milieu, on a introduit des interactions PQG-jets, qui correspondent aux processus collisionnels et radiatifs. Les corrélations entre deux particules finales des cascades, dont une représente un quark trigger, ont été examinées comme moyen pour distinguer les modèles.Résultats : La dépendance de l’ouverture angulaire pour des corrélations entre deux particules en fonction des énergies des particules peut servir comme moyen pour séparer les mécanismes collisionnels et radiatifs de la perte d’énergie dans le milieu. / Context: Quantum chromodynamics (QCD), the theory of the strong interactions, predicts a new state of matter, the quark-gluon plasma (QGP), where its fundamental degrees of freedom, the quarks and gluons, behave quasi-freely. The required high temperatures and/orparticle densities can be expected for the early stages of the universe and in neutron stars, but have lately become accessible by highly energetic collisions of heavy ion cores. Commonly, these experiments study the QGP by the detection of hard probes, i.e. highly energetic particles, most notably heavy quarks, that pass the medium. The mechanisms of their energy-loss in the QGP are not yet completely understood. In particular, they are attributed to processes of either additional, medium induced radiation or 2 to 2 particle scattering, or combinations thereof.Methods: In a theoretical, phenomenological approach to search for new observables that allow discriminating between these collisional and radiative energy-loss mechanisms a Monte-Carlo algorithm that simulates the formation of particle cascades from an initial particle was implemented. For the medium, different types of QGP-jet interactions, corresponding to collisional and/orradiative energy loss, were introduced. Correlations between pairs of final cascade particles, where one represents a heavy trigger quark, were investigated as a means to differentiate between these models.Findings: The dependence of angular opening for two particle correlations as a function of particle energy may provide a means to disentangle collisional and radiative mechanisms of in-medium energy loss.

The structural lineament mapping of southern India along withgeological, geochronological datasets help in redefining the Precambrian crustal blocks.The newly proposed Kumta and Mercara suture zones welding Archean crustal blocks in western peninsular India offer critical insights into the crustal evolution of Gondwana. The Kumta suturemainly consists of schistose rocks including quartz-phengite, garnet-biotite, chlorite, fuchsite and marble, whereas the Mercara suture contains mylonitic quartzo-feldspathic gneiss, garnet-kyanite-sillimanite gneiss, calc-silicate granulite and metagabbro. Metamorphic pressure-temperature estimations (Kumta suture: 11-18 kbar at 790-550oC; Mercara suture: 13 kbar at 825oC) suggest that, the sediments have undergone subduction to greater depths. The K-Ar age of biotite, phengite and U-Pb dating of zircon yields consistent metamorphic age of 1100-1400 Ma. In situ zircon 176Lu/177Hf isotope analysis shows wide range of εHf (t) values indicating the protolith sediments were derived from Paleo-Neoarchean juvenile crust that mixed with recycled older crust. The Bondla ultramafic-gabbro complex, northwest of the Kumta suture contains basalt, dolerite, gabbro, serpentinite, chromitite, peridotite and chromian spinel chemistry suggests evolution in a supra-subduction zone arc tectonic setting.The Sirsi shelf towards east of the Kumta suture, contains weakly deformed sedimentary rocks (limestone, shale, banded iron formations, greywacke, sandstone and quartzite) unconformable on relatively high-grade ca. 2571 Ma gneisses of the Dharwar craton. The Karwar block to the west is composed of weakly metamorphosedca. 3200 Ma tonalite-trondhjemite-granodiorite (TTG) with enclaves of amphibolite. In situ zircon 176Lu/177Hf isotope analysis and whole-rock 143Nd/144Nd isotopic analysis of TTGs show positive εHf and εNd values indicating ca. 3200 Ma juvenile crust. The Coorg block consists of ca. 3200 Ma charnockite, mafic granulites, hornblende-biotite gneiss, garnet-hornblende gabbro and anorthosite.In situ zircon 176Lu/177Hf isotope analysis indicates source as mixture of juvenile crust and older recycled crustal materials. Synthesis of the above results with published data suggests that Kumta and Mercara suture zones incorporate Paleoarchean to Mesoproterozoic sedimentssubjected to high-pressure metamorphism in the late Mesoproterozoic. Metamorphic P-T estimations of mafic granulite and U-Pb zircon geochronology of pelitic gneisses from Betsimisaraka suture zone, Madagascar suggests the rocks were underwent metamorphism at c. 24 kbar and c. 780°C during Mesoproterozoic suturing of Antongil-Masora blocks with the Antananarivo block.From the integration of above results with the new geophysical results and published data Mesoproterozoic Kumta-Mercara suture is interpreted as eastern extension of the Mesoproterozoic Betsimisaraka suture of Madagascar into western India.

Lipid bilayers are key components of biomembranes; they are self-assembled two-dimensional structures, primarily serving as barriers to the leakage of cell's contents. Lipid bilayers are typically charged in aqueous solution and may electrostatically interact with each other and with their environment. In this work, we investigate electrostatics of charged lipid bilayers with the main focus on the binding and bending of the bilayers. We first present a theoretical approach to charge-correlation attractions between like-charged lipid bilayers with neutralizing counterions assumed to be localized to the bilayer surface. In particular, we study the effect of nonzero ionic sizes on the attraction by treating the bilayer charges (both backbone charges and localized counterions) as forming a two-dimensional ionic fluid of hard spheres of the same diameter <i>D</i>. Using a two-dimensional Debye-H??ckel approach to this system, we examine how ion sizes influence the attraction. We find that the attraction gets stronger as surface charge densities or counterion valency increase, consistent with long-standing observations. Our results also indicate non-trivial dependence of the attraction on separations <i>h</i>: The attraction is enhanced by ion sizes for <i>h</i> ranges of physical interest, while it crosses over to the known <i>D</i>-independent universal behavior as <i>h</i> &rarr; &infin;; it remains finite as <i>h</i> &rarr; 0, as expected for a system of finite-sized ions. We also study the preferred curvature of an asymmetrically charged bilayer, in which the inner leaflet is negatively charged, while the outer one is neutral. In particular, we calculate the relaxed area difference &Delta; <i>A</i>₀ and the spontaneous curvature <i>C</i>₀ of the bilayer. We find &Delta; <i>A</i>₀ and <i>C</i>₀ are determined by the balance of a few distinct contributions: net charge repulsions, charge correlations, and the entropy associated with counterion release from the bilayer. The entropic effect is dominant for weakly charged surfaces in the presence of monovalent counterions only and tends to expand the inner leaflet, leading to negative &Delta; <i>A</i>₀ and <i>C</i>₀. In the presence of even a small concentration of divalent counterions, however, charge correlations counterbalance the entropic effect and shrink the inner leaflet, leading to positive &Delta; <i>A</i>₀ and <i>C</i>₀. We outline biological implications of our results.

While realistic in vitro testing of dry powder inhalers (DPIs) can be used to establish in vitro–in vivo correlations (IVIVCs) and predict in vivo lung doses, the aerodynamic particle size distributions (APSDs) of those doses and their regional lung deposition remains unclear. Four studies were designed to improve testing centered on the behavior of Novolizer®. Different oropharyngeal geometries were assessed by testing different mouth-throat (MT) models across a realistic range of inhalation profiles (IPs) with Salbulin® Novolizer®. Small and large Virginia Commonwealth University (VCU) and Oropharyngeal Consortium (OPC) models produced similar ranges for total lung dose in vitro (TLDin vitro), while results for medium models differed significantly. While either group may be selected to represent variations in oropharyngeal geometry, OPC models were more difficult to use, indicating that VCU models were preferable. To facilitate simulation of human IPs through DPIs, inhalation profile data from a VCU clinical trial were analyzed. Equations were developed to represent the range of flow rate vs. time curves for use with DPIs of known airflow resistance. A new method was developed to couple testing using VCU MT models and simulated IPs with cascade impaction to assess the APSDs of TLDin vitro for Budelin® Novolizer®. This method produced IVIVCs for Budelin’s total lung dose, TLD, and was sufficiently precise to distinguish between values of TLDin vitro and their APSDs, resulting from tests using appropriately selected MT models and IPs. For example, for slow inhalation, TLD values were comparable in vivo and in vitro; TLDin vitro ranged from 12.2±2.9 to 66.8±1.7 mcg aerosolized budesonide while APSDs in vitro had mass median aerodynamic diameters of 3.26±0.27 and 2.17±0.03 µm, respectively. To explore the clinical importance of these variations, a published computational fluid dynamic (CFD) model was modified and coupled to accept the output of realistic in vitro tests as initial conditions at the tracheal inlet. While simplified aerosol size metrics and flow conditions used to shorten CFD simulations produced small differences in theoretical predictions of regional lung deposition, the results broadly agreed with the literature and were generally consistent with the median values reported clinically for Budelin.

Orientador: Jeffrey Frederico Lui / Banca: Lucia Galvão de Albuquerque / Banca: Lenira El Faro Zadra / Resumo: Para estimar parâmetros genéticos para o número total de leitões nascidos (NLNT) e nascidos vivos (NLNV), empregaram-se modelos de repetibilidade, uni-características, bi-características, e de regressão aleatória (MRA). Os grupos de contemporâneos (GC) empregados nos três primeiros modelos foram: GC1 (granja-anoépoca) GC2 (granja-ano-mês) e GC3 (granja-ano-semana) relacionados com local e data em que ocorreu a parição. Para NLNT e NLNV, a herdabilidade (h2) estimada pelo modelo de repetibilidade foi de 0,09 ± 0,02. Nos modelos uni-características, a definição GC3 levou à estimativas mais elevadas nas ultimas parições. O modelo de repetibilidade com três classes de variâncias residuais foi o que apresentou melhor ajuste segundo o Teste da Razão de Verossimilhança (LRT) e o Critério de Informação de Akaike (AIC), para ambas as características. Dois MRA adicionais também foram ajustados para ambas as características. Para NLNT, um MRA linear e um quadrático de rank 2, ambos com três classes de variâncias residuais. Para NLNV, o primeiro foi um MRA linear, o segundo foi um MRA linear (genética) e quadrática com rank 2 (ambiente permanente). As estimativas de herdabilidade obtidas pelos MRA foram menores que as para o modelo multi-característica. As correlações genéticas obtidas pelos MRA tenderam a diminuir com o decorrer das parições, para ambas características. As correlações genéticas entre ordens de parição, de maneira geral foram altas, indicando que ao selecionar-se para primeira ganhos genéticos podem ser obtidos nas parições subseqüentes. / Abstract: Repeatability, single-trait, multiple-trait (MTM) and random regression models (RRM) were used with the objective to estimate genetic parameters for the number of piglets born in total (NOBT) and the number of piglets born alive (NOBA). Three different structures of cotemporary groups were applied: CG1 (herdyear- season), CG2 (herd-year-monthly) e CG3 (herd-year-weekly). For NOBT and NOBA, the estimates of heritability by repeatability model, were 0.09 ± 0.02. The estimates of heritability by single-trait model with CG3 definition were higher in 5th and 6th parities. The repeatability model with three classes of residual variances presented best fit. Two additional RRM were adjusted for both traits. For NOBT a linear and a quadratic RRM with rank 2, and three classes of residual variances, were utilized and for NOBA a linear RRM and Linear, for genetics effects, and quadratic with rank 2, for permanent environmental. The heritability estimates by RRM model were lower than MTM. The genetic correlations estimated by RRM tended to decrease over parities, for both traits. The genetics correlations were high among the most parities, indicating that the selection in the first parity will result in genetic gains in later parities. / Mestre

Resumo: A seleção baseada em características reprodutivas tem sido muito empregada em programas de melhoramento genético de suíno. Assim, objetivaram-se avaliar os efeitos ambientais e genéticos que influenciam o intervalo desmame-cio (IDC) e verificar sua influência no número de nascidos total (TL), nascidos vivos (NV) e mortos (NM) em fêmeas suínas. Para análise dos efeitos ambientais, utilizaram-se 8.104 dados da 1ª a 6ª ordem de parição, e, para as estimativas dos parâmetros genéticos, apenas as informações do 1º ao 3º IDC, o que resultou em 6.548 observações, que foram analisadas pelo método REML, utilizando-se modelos uni e multicaracterística. Para este último, considerou-se cada IDC (1º, 2º e 3º) como uma característica distinta. Avaliaram-se, também, as correlações genéticas entre o IDC, TL, NM e idade ao primeiro parto (IPP). Para os fatores ambientais, o modelo incluiu como efeitos fixos rebanho, linhagem, ano (AP) e estação (EP) de parto, e as covariáveis idade da porca ao parto (IDPP), TL e duração da lactação (DL). A DL, na forma linear, e a IDPP, na forma quadrática, influenciaram o IDC. Rebanho, AP e EP foram fontes de variação significativas, enquanto TL e linhagem não o foram. Não foi observada influência do IDC sobre TL, NV, nem sobre NM. A herdabilidade estimada para o IDC pelo modelo de repetibilidade foi baixa. As correlações genéticas entre os IDC (1º, 2º e 3º) foram de moderada a baixa magnitude, evidenciando que o modelo multicaracterística é mais indicado para as estimativas de parâmetro genético nessa população. As correlações genéticas entre IDC, TL e NM, assim como IDC e IPP foram favoráveis à seleção. / Abstract: Selection for reproductive traits has been largely used in swine breeding programs. The aims of this study were to evaluate environmental and genetic effects that affect the weaning-to-estrus interval (WEI) in sows and to assess their influence on litter size (LS), number of live born (LP) and dead born piglets (DP). Data consisting of 8,104 WEI from the 1st to 6th farrowing recorded in two herds were used for environmental analysis, but for estimating the genetic parameters only data from the 1st to 3rd farrowing were used, totalling 6,548 records. Genetic analysis was performed using the REML method with single and multitrait models, where each WEI was considered as a different trait. Genetic correlations among WEI, LS, DP and age at first farrowing (AFF) were also estimated using a multitrait model. For the environmental analysis, the model included as fixed effects the herd, line, and year (YF) and season (SF) of farrowing, and as covariates the sow's age at farrowing (SAF), LS, and lactation length (LL). The effects were linear for LL and quadratic for SAF. The herd, YF and SF were important sources of variation, whereas LS and line were not significant. There were no effects of WEI on the litter traits (LS, LP and DP). The heritability estimated for WEI was low, and genetic correlations among its different intervals were of moderate to low magnitude, evidencing that a multitrait model was more indicated for estimating the genetic parameters for this trait in this population. The genetic correlations between WEI and LS, DP and AFF would be favourable in a selection. / Orientador: Jeffrey Frederico Lui / Coorientadora: Lúcia Galvão de Albuquerque / Banca: Humberto Tonhati / Banca: Joslaine Noely dos Santos Gonçalves Cyrillo / Mestre