Long-term stability of retinal function despite retained intraocular metallic foreign body.

BACKGROUND: Persisting metallic intraocular foreign bodies (IOFB) with a ferrous content have been associated with ocular siderosis and retinal degeneration. We describe two patients in whom a metallic IOFB containing iron was left embedded for many years in the choroid and sclera after having penetrated through the vitreous and the retina. HISTORY AND SIGNS: Two male patients, aged 41 and 48 years, presented with a metallic IOFB sustained during a work accident involving metal tools. THERAPY AND OUTCOME: For the first patient it was deemed unwise to operate, as the IOFB was also lodged very deeply in the choroid and sclera in the inferior temporal quadrant. The second patient underwent pars plana vitrectomy, but the IOFB could not be removed surgically as it was too deeply embedded in the sclera and choroid. After a period of 6 years (Case 1) and 4 years (Case 2) of follow-up, visual acuity remained at 1.0 and the IOFB was encased in a fibrotic capsule in both cases. Full-field and multifocal electroretinograms showed an inter-ocular asymmetry at baseline, which remained stable during the follow-up. CONCLUSIONS: Ocular siderosis may not develop in patients with a deeply embedded metallic IOFB. Regular monitoring of both visual function and the electroretinogram is mandatory when the IOFB is left inside the eye.

Spatio-temporal dynamics and transition from asymptotic equilibrium to bounded oscillations in Chrysomya albiceps (Diptera, Calliphoridae)

The sensitivity of parameters that govern the stability of population size in Chrysomya albiceps and describe its spatial dynamics was evaluated in this study. The dynamics was modeled using a density-dependent model of population growth. Our simulations show that variation in fecundity and mainly in survival has marked effect on the dynamics and indicates the possibility of transitions from one-point equilibrium to bounded oscillations. C. albiceps exhibits a two-point limit cycle, but the introduction of diffusive dispersal induces an evident qualitative shift from two-point limit cycle to a one fixed-point dynamics. Population dynamics of C. albiceps is here compared to dynamics of Cochliomyia macellaria, C. megacephala and C. putoria.

Positional stability of holographic optical traps

The potential of digital holography for complex manipulation of micron-sized particles with optical tweezers has been clearly demonstrated. By contrast, its use in quantitative experiments has been rather limited, partly due to fluctuations introduced by the spatial light modulator (SLM) that displays the kinoforms. This is an important issue when high temporal or spatial stability is a concern. We have investigated the performance of both an analog-addressed and a digitally-addressed SLM, measuring the phase fluctuations of the modulated beam and evaluating the resulting positional stability of a holographic trap. We show that, despite imparting a more unstable modulation to the wavefront, our digitally-addressed SLM generates optical traps in the sample plane stable enough for most applications. We further show that traps produced by the analog-addressed SLM exhibit a superior pointing stability, better than 1 nm, which is comparable to that of non-holographic tweezers. These results suggest a means to implement precision force measurement experiments with holographic optical tweezers (HOTs).

Stability of periodic orbits of coupled-map lattices

We consider the stability properties of spatial and temporal periodic orbits of one-dimensional coupled-map lattices. The stability matrices for them are of the block-circulant form. This helps us to reduce the problem of stability of spatially periodic orbits to the smaller orbits corresponding to the building blocks of spatial periodicity, enabling us to obtain the conditions for stability in terms of those for smaller orbits.

Stability and consistency of coping in adolescence : A longitudinal study

Resumen tomado de la publicaci??n

Spatial and temporal variability of the concentration field from localized releases in a regular building array

Spatial and temporal fluctuations in the concentration field from an ensemble of continuous point-source releases in a regular building array are analyzed from data generated by direct numerical simulations. The release is of a passive scalar under conditions of neutral stability. Results are related to the underlying flow structure by contrasting data for an imposed wind direction of 0 deg and 45 deg relative to the buildings. Furthermore, the effects of distance from the source and vicinity to the plume centreline on the spatial and temporal variability are documented. The general picture that emerges is that this particular geometry splits the flow domain into segments (e.g. “streets” and “intersections”) in each of which the air is, to a first approximation, well mixed. Notable exceptions to this general rule include regions close to the source, near the plume edge, and in unobstructed channels when the flow is aligned. In the oblique (45 deg) case the strongly three-dimensional nature of the flow enhances mixing of a scalar within the canopy leading to reduced temporal and spatial concentration fluctuations within the plume core. These fluctuations are in general larger for the parallel flow (0 deg) case, especially so in the long unobstructed channels. Due to the more complex flow structure in the canyon-type streets behind buildings, fluctuations are lower than in the open channels, though still substantially larger than for oblique flow. These results are relevant to the formulation of simple models for dispersion in urban areas and to the quantification of the uncertainties in their predictions.

Spatio-temporal dynamics and transition from asymptotic equilibrium to bounded oscillations in Chrysomya albiceps (Diptera, Calliphoridae)

The sensitivity of parameters that govern the stability of population size in Chrysomya albiceps and describe its spatial dynamics was evaluated in this study. The dynamics was modeled using a density-dependent model of population growth. Our simulations show that variation in fecundity and mainly in survival has marked effect on the dynamics and indicates the possibility of transitions from one-point equilibrium to bounded oscillations. C. albiceps exhibits a two-point limit cycle, but the introduction of diffusive dispersal induces an evident qualitative shift from two-point limit cycle to a one fixed-point dynamics. Population dynamics of C. albiceps is here compared to dynamics of Cochliomyia macellaria, C. megacephala and C. putoria.

Temporal dynamics of stomatal conductance of plants under water deficit: can homeostasis be improved by more complex dynamics?

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dynamics of aggregate stability influenced by soil management and crop residues

The type of tillage and crop systems used can either degrade or cause a recovery of the structure of agricultural soils. The objective of this study was to determine the structural stability of the soil using mean weight diameter (MWD) of soil aggregates in three different periods of a succession of crops consisting of beans/cover plants/maize under no tillage (NT) and conventional tillage (CT) management systems. Soils were sampled at 0- to 5-cm and 5- to 15-cm depths in three periods (P1, P2, P3): 1) November 2002 (spring/summer), 2) April 2003 (beginning of autumn), and 3) December 2003 (end of spring/beginning of summer). Aggregate stability was determined by wet sieving. The effects of the tillage systems, vegetal residues, and sampling depths on the structural stability of the aggregates were assessed and then related to organic matter (OM) contents. Aggregate stability showed temporal variation as a function of OM contents and sampling period. No tillage led to high MWD values in all study periods. The lowest MWD values and OM contents were observed 4 months after the management of the residues of cover plants. This finding is consistent with the fact that at the time of the samplings, most of the OM had already mineralized. The residues of sunn-hemp, millet, and spontaneous vegetation showed similar effects on soil aggregate stability.

ANT (HYM, FORMICIDAE) MOSAIC STABILITY IN BAHIAN COCOA PLANTATIONS - IMPLICATIONS FOR MANAGEMENT

Mapping and collection of ants in cocoa trees in a 1 ha plot in the south of Bahia, Brazil, revealed three dominant species of the ant mosaic: Wasmannia auropunctata, Ectatomma tuberculatum and Azteca chartifex spiriti. A. chartifex demonstrated a larger influence in the cocoa plantation due to its spatial and temporal (1 y) stability in the same cocoa trees, and its capacity for territorial expansion. The management of A. chartifex for controlling insect pests of cocoa is strongly recommended. Considerations of temporal permanence of mosaic dominant ants should be a necessary criteria for ant management in tropical tree crops.

Persistence and stability of cichlid assemblages in neotropical floodplain lagoons

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Variação temporal da resistividade elétrica em contaminação por gasolina

The definition of models and base parameters for application of investigation tools in environment with high complexity are a basic premise to any sciences. The geophysics is a science with solid theoretical base and applications in diversified areas of the sciences geological, astronomical, meteorological, among many others. Its application in environmental studies is relatively recent and needs further research. To understand the behavior of resident contaminants in a dynamic and complex environment as the geological, it requests studies in scale laboratorial, under control of factors seasonality variable. This work simulates a leak of gasoline in soil, under conditions and in laboratory scale, with the objective of monitoring the temporary behavior of the hydrocarbon under the optics of variation of the parameter physical electric resistivity. The results indicate increase of the resistivity in recent periods the contamination, followed for stability in the values and finally fall and return tendency to the natural conditions.

Variabilidade temporal e mapeamento dos dados climáticos de Botucatu-SP

O trabalho teve objetivo estudar a variabilidade temporal da temperatura do ar, precipitação pluviométrica e umidade relativa do ar na cidade de Botucatu-SP, Brasil, utilizando técnicas geoestatísticas. Os dados de precipitação pluviométrica, temperatura do ar e umidade relativa do ar utilizados no presente estudo são provenientes da Estação Meteorológica da Fazenda Lageado, da Faculdade de Ciências Agronômicas-UNESP. As observações foram realizadas no período de 1988 a 2007, referem-se ao total mensal de precipitação pluvial expressa em altura de lâmina d'água (mm), médias mensais de temperatura em ºC e umidade relativa em %. Os dados foram avaliados por meio da estatística clássica e geoestatística. As variáveis climáticas tiveram sua dependência verificada por variogramas, apresentando dependência temporal maior que 76%. A série temporal de umidade relativa do ar foi a que apresentou maior alcance (8,67 meses) e, conseqüentemente, maior estabilidade climática. O conhecimento da distribuição temporal das variáveis climáticas é importante para o estudo e realização do zoneamento agroclimático, bem como para o dimensionamento do sistema de irrigação das culturas.

Variação espaço-temporal do zooplâncton em diferentes ambientes do médio Rio Xingu-PA

Estudos relacionados à variação espacial e sazonal das comunidades zooplanctônicas de um trecho do médio Rio Xingu, no Estado do Pará, foram realizados em dois ambientes de lagos e de canal. As coletas foram realizadas com periodicidade mensal durante um ciclo anual, estimando-se os parâmetros:diversidade, densidade, biomassa, produção secundária e os grupos funcionais de cada localidade (lago, remanso e corredeira). Um total de 166 espécies pertencentes principalmente a três grupos taxonômicos foi registrado para todos os ambientes: Rotifera 141 espécies; Cladocera com 20 espécies; e Copepoda com cinco espécies. A maior densidade numérica foi de Rotifera no período de seca, com diminuição na cheia. As estimativas do número esperado de espécies baseado nas curvas de rarefação mostrou que a diversidade zooplanctônica no lago Pimental, ambientes de remanso e corredeiras, não atingiram a assíntota para a riqueza total de espécies coletadas. Para o Lago da Ilha Grande, a riqueza foi menor em relação aos outros ambientes estudados, e atingiu a assíntota no décimo segundo mês de coleta. A densidade total média (org.m-3) do zooplâncton, para os ambientes de canal do rio, nos pontos de Boa Esperança e Arroz Cru, apresentou uma variação sazonal com os maiores valores para o período da seca, sendo que os rotíferos constituíram o grupo taxonômico melhor representado em termos de densidade. A biomassa total seca apresentou uma variação de 0,063 a 2,2 g.m-2. O lago da Ilha Grande foi o ambiente que apresentou maior dispersão na biomassa com valores de 0,39 a 1,2 g.m-2 no período da cheia e 0,66 g.m-2 para período da seca. Sete grupos foram encontrados em 35% de similaridade entre os ambientes estudados na variação sazonal. O grupo formado por organismos do Lago de Pimental no período de cheia foi o mais dissimilar. De acordo com a análise de similaridade das porcentagens (SIMPER), houve uma similaridade interna média, no período da cheia, dos ambientes de corredeira com aproximadamente 58%; remanso com similaridade média de 48% e de Lago, apresentando uma baixa similaridade interna de 23%. A dissimilaridade foi maior entre os ambientes de corredeira e lago, ambos no período de cheia (70%). A Análise de similaridade bifatorial indicou que não há diferenças significativas entre os ambientes estudados (ANOSIM r = 0,263; P = 0,2). Os lagos foram os que apresentaram comunidades vi zooplanctônicas estatisticamente diferenciadas dos demais ambientes no médio Rio Xingu. Para os ambientes estudados, as principais espécies encontradas apresentaram diferentes hábitos alimentares, sendo estas detritívoras, filtradoras e onívoras. Os resultados obtidos para os ambientes aquáticos do médio Rio Xingu mostraram um padrão de maior diversificação dos Rotifera e dos Cladocera, confirmando os estudos para outros ambientes amazônicos, onde ao que parece, ocorre esta tendência independentemente do tipo de águas dentro da classificação de Sioli. Os distintos ambientes apresentaram uma redução na densidade do zooplâncton, que acompanharam o aumento do volume das águas do rio, e que pode estar associada com o forte efeito diluidor das águas pelo aumento do nível do rio, e por sua vez, um efeito perturbador na estabilidade dos ambientes de lago.

Variação espaço-temporal de atributos ecológicos da ictiofauna de um grande reservatório Neotropical

Pós-graduação em Aquicultura - FCAV