An application of LANDSAT multispectral imagery for the classification of hydrobiological systems, Shark River Slough, Everglades National Park, Florida

Multivariant hydrologic parameters over the Shark River Slough were investigated. Ground truth was established utilizing U-2 infrared photography and comprehensive field data to define a control network which represented all hydrobiological systems in the slough. These data were then applied to LANDSAT imagery utilizing an interactive multispectral processor which generated hydrographic maps through classification of the slough and defined the multispectral surface radiance characteristics of the wetlands areas in the park. The spectral response of each hydrobiological zone was determined and plotted to formulate multispectral relationships between the emittent energy from the slough in order to determine the best possible multispectral wavelength combinations to enhance classification results. The extent of each hydrobiological zone in slough was determined and flow vectors for water movement throughout the slough established

The State of the Art in Turbulence Modelling in Brazil

The present work discusses at length the current status of turbulent research in Brazil, After eight introductory sections on the subject, where some general aspects of the problem are presented, and a brief review of some scientific and engineering approaches is given, the paper strolls over four specific sections, analyzing all work carried out in Brazil in the past twenty five years on turbulence. In fact, the present compilation is restricted to the main events sponsored by the Brazilian Society of Mechanical Sciences. The present review quotes 284 references, presents 6 tables and ¡6 figures. The paper contents is: Paper Outline, Some Insights, The Traditional Approaches, Some Basic Working Rules, Turbulence Models, One-Point Turbulence Closure Models, Some Other Aproaches to Turbulence Modelling, Some Major Achievements, A Bit of History, Statistics, A Personal View, Gallery, Final Remarks, Cited Bibliography and Compiled Bibliography.Indisponível

Self-organized criticality in a rice-pile model

We present a new model for relaxations in piles of granular material. The relaxations are determined by a stochastic rule which models the effect of friction between the grains. We find power-law distributions for avalanche sizes and lifetimes characterized by the exponents $\tau = 1.53 \pm 0.05$ and $y = 1.84 \pm 0.05$, respectively. For the discharge events, we find a characteristic size that scales with the system size as $L^\mu$, with $\mu = 1.20 \pm 0.05$. We also find that the frequency of the discharge events decrease with the system size as $L^{-\mu'}$ with $\mu' = 1.20 \pm 0.05$.Comment: 4 pages, RevTex, multicol, epsf, rotate (sty files provided). To appear Phys. Rev. E Rapid Communication (Nov or Dec 96

Dendritic Plasmonics for Mid-Infrared Spectroscopy

Metallic nanostructures that exhibit tailored optical resonances spanning from the near to mid-infrared spectral range are of particular interest for spectroscopic and optical measurements in these spectral domains that can benefit from localized surface-enhancement effects. Plasmon resonances shifted in the near or mid-infrared range could be used to further enhance the excitation and/or the emission of an optical process. Surface-enhanced infrared absorption (SEIRA) is one of such processes and can particularly benefit from plasmon-enhanced local fields yielding an increase in sensitivity towards the detection of an analyte. Herein, we have fabricated a series of gold dendritic nanostructures, prepared by electron-beam lithography, that exhibit plasmon resonances spanning the near and mid-infrared spectral regions. We explore the influence of the number of branches of the dendritic structures, as well as the length of each generation together with the overall effect of the shape and symmetry on the resulting optica

Universality classes for rice-pile models

We investigate sandpile models where the updating of unstable columns is done according to a stochastic rule. We examine the effect of introducing nonlocal relaxation mechanisms. We find that the models self-organize into critical states that belong to three different universality classes. The models with local relaxation rules belong to a known universality class that is characterized by an avalanche exponent $\tau \approx 1.55$, whereas the models with nonlocal relaxation rules belong to new universality classes characterized by exponents $\tau \approx 1.35$ and $\tau \approx 1.63$. We discuss the values of the exponents in terms of scaling relations and a mapping of the sandpile models to interface models.Comment: 4 pages, including 3 figure

A novel radiographic scoring system for growth abnormalities and structural change in children with juvenile idiopathic arthritis of the hip

Background: Approximately 20\u201350% of children with juvenile idiopathic arthritis (JIA) have hip involvement within 6 years of diagnosis. Scoring systems for hip-related radiographic changes are lacking. Objective: To examine precision of potential radiographic variables and to suggest a scoring system. Materials and methods: We reviewed a set of 75 pelvic radiographs from 75 children with JIA hip involvement across two European centres. We assessed findings of (1) destructive change and (2) growth abnormality, according to a pre-defined scoring system. All radiographs were scored independently by two sets of radiologists. One set scored the radiographs a second time. We used kappa statistics to rate inter- and intra-observer variability. Results: Assessment of erosions of the femoral head, femoral neck and the acetabulum showed moderate to good agreement for the same reader (kappa of 0.5\u20130.8). The inter-reader agreement was, however, low (kappa of 0.1\u20130.3). There was moderate to high agreement for the assessment of femoral head flattening (kappa of 0.6\u20130.7 for the same reader, 0.3\u20130.7 between readers). Joint space narrowing showed moderate to high agreement both within and between observers (kappa of 0.4\u20130.8). Femoral neck length and width measurements, the centrum\u2013collum\u2013diaphysis angle, and trochanteric\u2013femoral head lengths were relatively precise, with 95% limits of agreement within 10\u201315% of the observer average. Conclusion: Several radiographic variables of destructive and growth abnormalities in children with hip JIA have reasonable reproducibility. We suggest that future studies on clinical validity focus on assessing only reproducible radiographic variables

U mobilization and associated U isotope fractionation by sulfur-oxidizing bacteria

Uranium (U) contamination of the environment causes high risk to health, demanding for effective and sustainable remediation. Bioremediation via microbial reduction of soluble U(VI) is generating high fractions (>50%) of insoluble non-crystalline U(IV) which, however, might be remobilized by sulfur-oxidizing bacteria. In this study, the efficacy of Acidithiobacillus (At.) ferrooxidans and Thiobacillus (T.) denitrificans to mobilize non-crystalline U(IV) and associated U isotope fractionation were investigated. At. ferrooxidans mobilized between 74 and 91% U after 1 week, and U mobilization was observed for both, living and inactive cells. Contrary to previous observations, no mobilization by T. denitrificans could be observed. Uranium mobilization by At. ferrooxidans did not cause U isotope fractionation suggesting that U isotope ratio determination is unsuitable as a direct proxy for bacterial U remobilization. The similar mobilization capability of active and inactive At. ferrooxidans cells suggests that the mobilization is based on the reaction with the cell biomass. This study raises doubts about the long-term sustainability of in-situ bioremediation measures at U-contaminated sites, especially with regard to non-crystalline U(IV) being the main component of U bioremediation