Summary1. Much of the current understanding of ecological systems is based on theory that does not explicitly take into account individual variation within natural populations. However, individuals may show substantial variation in resource use. This variation in turn may be translated into topological properties of networks that depict interactions among individuals and the food resources they consume (individual-resource networks). 2. Different models derived from optimal diet theory (ODT) predict highly distinct patterns of trophic interactions at the individual level that should translate into distinct network topologies. As a consequence, individual-resource networks can be useful tools in revealing the incidence of different patterns of resource use by individuals and suggesting their mechanistic basis. 3. In the present study, using data from several dietary studies, we assembled individual-resource networks of 10 vertebrate species, previously reported to show interindividual diet variation, and used a network-based approach to investigate their structure. 4. We found significant nestedness, but no modularity, in all empirical networks, indicating that (i) these populations are composed of both opportunistic and selective individuals and (ii) the diets of the latter are ordered as predictable subsets of the diets of the more opportunistic individuals. 5. Nested patterns are a common feature of species networks, and our results extend its generality to trophic interactions at the individual level. This pattern is consistent with a recently proposed ODT model, in which individuals show similar rank preferences but differ in their acceptance rate for alternative resources. Our findings therefore suggest a common mechanism underlying interindividual variation in resource use in disparate taxa.

Standard polynomial fitting methods are inconsistent in their formulation. The regional field is approximated by a polynomial fitted to the observed field. As a result, in addition to the nonuniqueness in the definition of the regional field, the fitted polynomial is strongly influenced by the residual field (observed field minus regional field). We present a regional‐residual separation method for gravity data which uses a robust procedure to determine the coefficients of a polynomial fitted to the observations. Under the hypothesis that the regional can be modeled correctly by the polynomial surface, the proposed method minimizes the influence of the residual field in the fitted surface. The proposed method was applied to real gravity data from Ceará state, Brazil, and produced information on zones of possible crustal thickening and the occurrence of lower‐crustal granulitic rocks thrust into the shallow subsurface.

Janne eyre fernandes brito da costa 4 vanda maria ferreira siMões 5Resumo OBJETIVO: Analisar a associação da gravidez na adolescência com prematuridade. MÉTODOS: Foram incluídas todas as pacientes que pariram num hospital terciário universitário do Maranhão, no período de julho a dezembro de 2006, alocando-as em dois grupos: adolescentes (10 a 19 anos de idade) e adultas (20 a 34 anos). As variáveis estudadas foram: escolaridade, situação conjugal, número de consultas no pré-natal, idade gestacional no início do pré-natal, duração da gestação, tipo de parto e peso ao nascer. Os dados foram processados no programa Epi-Info, versão 3.4.1, e foram analisadas as associações entre as variáveis pela razão dos produtos cruzados, a odds ratio (OR), com intervalo de confiança (IC) de 95%; utilizaram-se também modelos de regressão logística. O nível de significância adotado foi de 0,05. RESULTADOS: Foram avaliadas 1.978 pacientes. Verificou-se frequência de 25,4% de partos em adolescentes, que apresentaram baixa escolaridade, ausência de companheiro, menor número de consultas no pré-natal, início tardio do pré-natal, baixo peso ao nascer (BPN) e prematuridade. Realizando a análise, tendo como variável desfecho a prematuridade, verificou-se nítida associação com baixo número de consultas do pré-natal (OR 3,0; IC95% 2,2-4,0) e início tardio do pré-natal (OR 1,9; IC95% 1,3-2,6), baixa escolaridade (OR 1,9; IC95% 1,4-2,5) em relação com a adolescência (OR 1,5; IC95% 1,1-1,9). As adolescentes tiveram menor incidência de cesárea (33,3%) que as adultas (49,4%), com diferença significativa, além de menor associação com pré-eclâmpsia e desproporção cefalopélvica. CONCLUSÕES: A gravidez na adolescência esteve associada a início tardio do pré-natal e baixo número de consultas pré-natal, além de baixa escolaridade, BPN, prematuridade e menor incidência de desproporção cefalopélvica e pré-eclâmpsia. Abstract PURPOSE:To analyze the association of pregnancy in adolescence and prematurity. METHODS: The study included all the patients who delivered at a teaching hospital in Maranhão State, from July to December 2006. The patients were divided into two groups: adolescents (10 to 19 years old) and adults (20 to 34 years old). The variables studied were: educational level, marital status, number of prenatal visits, gestational age at the onset of prenatal care, duration of gestation, delivery route and birth weight. Statistical analysis was performed using the Epi-Info software, version 3.4.1, and the associations between variables were analyzed by the odds ratio (OR), with a 95% confidence interval (CI). Models of logistic regression were also used. The level of significance adopted was 0.05. RESULTS: The study evaluated 1,978 patients. The frequency of deliveries in adolescents was 25.4%. This group presented low educational level, no mates, low number of prenatal visits, late onset of prenatal care, low birth weight and prematurity. In the analysis of prematurity as the outcome variable, there was a clear association with low number of pr...

BackgroundMaternal mortality and morbidity are among the top public health priorities in Brazil, being quite high, especially among the most disadvantage women. A case control study was developed to identify risk factors for severe maternal morbidity in Sao Luis, one of the poorest Brazilian State Capitals.MethodsThe case–control study was carried out between 01/03/2009 and 28/02/2010 in two public high-risk maternities facilities and in two intensive care units (ICUs) for referral of obstetric cases. All cases hospitalized due to complications during gestation period, childbirth or up to 42 days of puerperium and who fulfilled any of Mantel's and/or Waterstone's criteria were identified. Two controls per case were randomly selected among patients of the same clinics discharged for other reasons. Data were obtained through a structured interview as well as from medical charts and prenatal cards and included sociodemographic variables, clinical and obstetric histories, behavioral factors and exposure to stress factors during pregnancy, pre-natal assistance and obstetric complication and childbirth care.ResultsIn the final model of the unconditional logistic regression analysis, being older than 35 years (OR=3.11; 95% CI:1.53-6.31), previous hypertension (OR=2.52; 95% CI:1.09-5.80), history of abortion (OR=1.61; 95% CI:0.97-2.68), 4–5 pre-natal consultations (OR=1.78; 95% CI:1.05-3.01) and 1–3 pre-natal consultations (OR=1.89; 95% CI:1.03-3.49) were independently associated with severe maternal morbidity.ConclusionsThe results corroborate the importance of reproductive healthcare, of identifying a high-risk pregnancy and of a qualified and complete prenatal care to prevent severe morbid events.ResumoIntroduçãoA mortalidade e morbidade maternas estão entre os tópicos prioritários da Saúde Pública brasileira, especialmente na população de menor nível socioeconômico. Um estudo caso-controle foi desenvolvido para identificar os fatores de risco para morbidade materna grave em São Luís, capital de um dos estados mais pobres do Brasil.MétodoEstudo caso-controle realizado em duas maternidades públicas de alto risco e duas UTIs de referência aos casos obstétricos entre 01/03/2009 e 28/02/2010. Foram incluídas todas as pacientes internadas por complicação do período grávido-puerperal e que preenchiam os critérios de Waterstone e/ou Mantel para morbidade materna grave. Foram selecionados para cada caso, dois controles por sorteio aleatório dentre as pacientes internadas no mesmo período e mesma maternidade que o caso. As informações de domínio sociodemográfico, clínico, obstétrico, comportamental, exposição a eventos estressores na gestação, assistência ao pré-natal, intercorrências obstétricas e atenção ao parto, foram obtidas por meio de entrevista estruturada. As variáveis foram analisadas por modelo de regressão logística múltipla não condicional, baseado em modelo hierarquizado a priori.ResultadosForam identificados como fatores de risco para morbidade materna grave: idade >35 anos (OR=3,11; IC 95%:1,53-6,31), hipertens...

The application of a deconvolution imaging condition in wave-equation shot-profile migration is important to provide illumination compensation and amplitude recovery. Particularly if the aim is to successfully recover a measure of the medium reflectivity, an imaging condition that destroys amplitudes is unacceptable. We study a set of imaging conditions with illumination compensation. The imaging conditions are evaluated by the quality of the output amplitudes and artifacts produced. In numerical experiments using a vertically inhomogeneous velocity model, the best of all imaging conditions we tested is the one that divides the crosscorrelation of upgoing and downgoing wavefields by the autocorrelation of the downgoing wavefield, also known as the illumination map. In an application to Marmousi data, unconditional division by autocorrelation turned out to be unstable. Effective stabilization was achieved by smoothing the illumination map.

Present-day techniques to estimate the traveltime parameters of the common-reflection-surface (CRS) stack are tedious, time-consuming, and expensive processes based on local coherence analyses along a large number of trial surfaces. With the 2D CRS method, faster and cheaper determination is possible. The complete set of CRS parameters can be extracted from seismic data by an application of modern local-slope-extraction techniques. The necessary information about the CRS parameters is contained in the slopes of the common-midpoint section at the central point and one or several common-offset sections in its vicinity. We studied two procedures for the CRS parameter extraction technique. Their difference lies in the way the common-offset parameters are determined. One technique requires slope-derivative information (a possible source of instability); the other uses slope information at two different locations and less data redundancy. Testing on a synthetic data example proved that the procedures are sufficiently robust to allow for high-quality extraction of all CRS parameters from the extracted slope fields. In this way, the CRS parameter extraction can be sped up by several orders of magnitude as compared to the conventional procedure based on coherence analysis along trial surfaces.

The quality of seismic images obtained by reverse time migration ͑RTM͒ strongly depends on the imaging condition. We propose a new imaging condition that is motivated by stationary phase analysis of the classical crosscorrelation imaging condition. Its implementation requires the Poynting vector of the source and receiver wavefields at the imaging point. An obliquity correction is added to compensate for the reflector dip effect on amplitudes of RTM. Numerical experiments show that using an imaging condition with obliquity compensation improves reverse time migration by reducing backscattering artifacts and improving illumination compensation.

Anisotropy has significant effect on traveltime cross‐borehole tomography. Even relatively weak anisotropy cannot be ignored if accurate velocity estimates are desired, since isotropic traveltime tomography treats anisotropy as inhomogeneity. Traveltime data in our examples were synthetically generated by a ray‐tracing code for anisotropic media, and the computed quasi‐P‐wave traveltimes were subsequently inverted using the “dual tomography” technique (Carrion, 1991). The results of the tomographic inversion show typical artifacts due to the anisotropy, and that accurate imaging is impossible without taking the anisotropy into account.