Remediation actions by a risk assessment approach: a case study of mercury contamination

The risk assessment procedure for identifying the remediation actions which may be adopted at a mercury contaminated site, when the plants are upgraded in the future, is proposed. The potentially active exposure/migration pathways in the future arrangement of the area will be due to Hg contaminated subsoil as a primary source (vapor inhalation and groundwater leaching) and to groundwater as a possible secondary source (transport to the point of compliance). The data of mercury concentration in the soil were acquired through environmental monitoring campaigns, and were processed to establish the three-dimensional distribution of contamination in subsoil, to locate sources and to define their geometrical and chemical characteristics. Speciation tests of mercury in the soil indicated that the most abundant species present were poorly leachable under the site-specific environmental conditions, confirming the coefficient distribution value obtained by the leaching tests. Analytical and numerical fate and transport modeling tools were used to locate digging zones in the contaminated subsoil, so as to reduce the possible groundwater contaminant loading and to avoid the down-gradient exceeding the concentration limit according to regulations. Remediation actions additional to civil works were required, which consists of soil digging within one contamination source, for about 22,200 m3 of soil. In order to evaluate the Hazard Index (HI) for human receptors due to Hg vapor inhalation, the air concentration of volatile mercury at the exposure point was estimated, based on direct measurements carried out at the site. Simulation gave HI values below 1 for all tested scenarios, suggesting that public health is protected without any additional actions to the already scheduled plant upgrading and digging for groundwater protection

On the bend number of circular-arc graphs as edge intersection graphs of paths on a grid

Golumbic, Lipshteyn and Stern \cite{Golumbic-epg} proved that every graph can be represented as the edge intersection graph of paths on a grid (EPG graph), i.e., one can associate with each vertex of the graph a nontrivial path on a rectangular grid such that two vertices are adjacent if and only if the corresponding paths share at least one edge of the grid. For a nonnegative integer $k$, $B_k$-EPG graphs are defined as EPG graphs admitting a model in which each path has at most $k$ bends. Circular-arc graphs are intersection graphs of open arcs of a circle. It is easy to see that every circular-arc graph is a $B_4$-EPG graph, by embedding the circle into a rectangle of the grid. In this paper, we prove that every circular-arc graph is $B_3$-EPG, and that there exist circular-arc graphs which are not $B_2$-EPG. If we restrict ourselves to rectangular representations (i.e., the union of the paths used in the model is contained in a rectangle of the grid), we obtain EPR (edge intersection of path in a rectangle) representations. We may define $B_k$-EPR graphs, $k\geq 0$, the same way as $B_k$-EPG graphs. Circular-arc graphs are clearly $B_4$-EPR graphs and we will show that there exist circular-arc graphs that are not $B_3$-EPR graphs. We also show that normal circular-arc graphs are $B_2$-EPR graphs and that there exist normal circular-arc graphs that are not $B_1$-EPR graphs. Finally, we characterize $B_1$-EPR graphs by a family of minimal forbidden induced subgraphs, and show that they form a subclass of normal Helly circular-arc graphs

Exoplanet atmospheres with GIANO. I. Water in the transmission spectrum of HD 189733b

High-resolution spectroscopy (R $\ge$ 20,000) at near-infrared wavelengths can be used to investigate the composition, structure, and circulation patterns of exoplanet atmospheres. However, up to now it has been the exclusive dominion of the biggest telescope facilities on the ground, due to the large amount of photons necessary to measure a signal in high-dispersion spectra. Here we show that spectrographs with a novel design - in particular a large spectral range - can open exoplanet characterisation to smaller telescope facilities too. We aim to demonstrate the concept on a series of spectra of the exoplanet HD 189733 b taken at the Telescopio Nazionale Galileo with the near-infrared spectrograph GIANO during two transits of the planet. In contrast to absorption in the Earth's atmosphere (telluric absorption), the planet transmission spectrum shifts in radial velocity during transit due to the changing orbital motion of the planet. This allows us to remove the telluric spectrum while preserving the signal of the exoplanet. The latter is then extracted by cross-correlating the residual spectra with template models of the planet atmosphere computed through line-by-line radiative transfer calculations, and containing molecular absorption lines from water and methane. By combining the signal of many thousands of planet molecular lines, we confirm the presence of water vapour in the atmosphere of HD 189733 b at the 5.5-$\sigma$ level. This signal was measured only in the first of the two observing nights. By injecting and retrieving artificial signals, we show that the non-detection on the second night is likely due to an inferior quality of the data. The measured strength of the planet transmission spectrum is fully consistent with past CRIRES observations at the VLT, excluding a strong variability in the depth of molecular absorption lines.Comment: 10 pages, 8 figures. Accepted for publication in Astronomy & Astrophysics. v2 includes language editin

Arbitrage Pricing Theory (APT) e variáveis macroeconômicas. Um estudo empírico sobre o mercado acionário brasileiro

This paper analyses monthly returns of 10 share portfolios negotiated at Bovespa between 1987 and 1997 in order to test the APT model. Macroeconomic factors were created as sources of common variance of these assets. The factors were statistically significant in explaining the relationship between the asset returns in general; besides, evidence was found in favor of the APT.

Aspectos Percepto Motores e Cognitivos do Desenvolvimento de Crianças Com Síndrome de Down no Município de Vitória/ES

Grande parte da literatura atualmente vigente afirma que o desenvolvimento de crianças com Síndrome de Down ocorre com atraso quando comparado com o de crianças com desenvolvimento neuropsicomotor típico. Ao mesmo tempo, estudos têm mostrado que a estimulação, seja escolar ou clínica, desempenha importante papel no processo de desenvolvimento dessas crianças ao oferecer maiores oportunidades de experiências, minimizando, possivelmente, as grandes defasagens tão associadas a essa população. A presente pesquisa buscou avaliar os aspectos percepto-motores e cognitivos do desenvolvimento de crianças com Síndrome de Down, investigando a possível interdependência entre a motricidade e a estruturação da inteligência a partir de uma abordagem Piagetiana. Participaram da pesquisa 10 crianças com a síndrome, com idade entre 6 meses e 4 anos, sendo que oito estavam matriculadas nos Centros Municipais de Educação Infantil de Vitória/ES, uma em instituição de ensino privado da mesma cidade e uma não frequentava qualquer escola. Para a coleta de dados foi utilizado um roteiro de observação do comportamento motor para descrever os padrões de locomoção, de manipulação, de estabilidade, de percepção sensorial e corporal, e as Provas Piagetianas adaptadas, para a observação e descrição da construção das noções de objeto permanente, de causalidade física, de espaço e de tempo concernentes ao estágio sensório-motor do desenvolvimento cognitivo. Também foi aplicada uma anamnese com o cuidador principal da criança para contextualizar a rotina dos sujeitos. Os itens referentes às habilidades motoras e às noções sensório-motoras foram categorizados de forma qualitativa a partir de critérios pré-estabelecidos. Os dados foram tratados utilizando-se análise estatística exploratória e descritiva. Observou-se que os principais déficits motores e as maiores defasagens cognitivas foram apresentados pelas crianças mais novas da amostra. Da mesma forma, uma maior interdependência na relação entre os diferentes itens ocorreu nessas mesmas crianças. Acredita-se que o processo de desenvolvimento dessas crianças tende a se aproximar do que é tipicamente esperado com o passar da idade, ratificando a importância das estimulações a longo prazo para as crianças com Síndrome de Down

Molecular Investigations of PenA-mediated β-lactam Resistance in Burkholderia pseudomallei

Burkholderia pseudomallei is the etiological agent of melioidosis. Because of the bacterium’s intrinsic resistance and propensity to establish latent infections, melioidosis therapy is complicated and prolonged. Newer generation β-lactams, specifically ceftazidime, are used for acute phase therapy, but resistance to this cephalosporin has been observed. The chromosomally encoded penA gene encodes a putative twin arginine translocase (TAT)-secreted β-lactamase, and penA mutations have been implicated in ceftazidime resistance in clinical isolates. However, the role of PenA in resistance has not yet been systematically studied in isogenetic B. pseudomallei mutant backgrounds. We investigated the effects of penA deletion, point mutations, and up-regulation, as well as tat operon deletion and PenA TAT-signal sequence mutations. These experiments were made possible by employing a B. pseudomallei strain that is excluded from Select Agent regulations. Deletion of penA significantly (>4-fold) reduced the susceptibility to six of the nine β-lactams tested and ≥16-fold for ampicillin, amoxicillin, and carbenicillin. Overexpression of penA by single-copy, chromosomal expression of the gene under control of the inducible Ptac promoter, increased resistance levels for all β-lactams tested 2- to 10-fold. Recreation of the C69Y and P167S PenA amino acid substitutions previously observed in resistant clinical isolates increased resistance to ceftazidime by ≥85- and 5- to 8-fold, respectively. Similarly, a S72F substitution resulted in a 4-fold increase in resistance to amoxicillin and clavulanic acid. Susceptibility assays with PenA TAT-signal sequence and ΔtatABC mutants, as well as Western blot analysis, confirmed that PenA is a TAT secreted enzyme and not periplasmic but associated with the spheroplastic cell fraction. Lastly, we determined that two LysR-family regulators encoded by genes adjacent to penA do not play a role in transcriptional regulation of penA expression