CONCENTRAÇÃO DE SÓLIDOS SUSPENSOS POR ESPECTROFOTOMETRIA

The use of sensors with optical principles designed to estimate sediment transport, and mainly the concentration of suspended solids (CSS) constitutes a robust technique that is currently consolidated and well disseminated in the scientific community, thus configuring an important tool in research, management and control of river basins. The present study, carried out in a water body located near the mouth of the Coxim River - (Coxim, MS), consisted of comparing Nephelometric Techniques and the integrated area of ​​absorbance at wavelengths in the spectrum from 400 to 600 mm (A400-600) and these are measured using a UV/VIS spectrophotometer for indirect determination of CSS. This water body showed characteristics of high sediment input; and for the purpose of possible relationships between the parameters and the characterization of suspended sediments transported by the river, the granulometry (Medium Sand, Fine Sand, Silt and Clay) of the processed samples was determined. The interactions between the parameters to indirectly determine CSS showed the following correlations: (p<0.001); Nephelometric with (R=0.942) and A400-600 (R=0.959); and the particle size fractions, in turn, indicated: (%) of Silt (52.6 ± 17.4), in addition to values ​​close to the distribution of Clay (15.3 ± 6.73), Fine Sand (15.6 ± 10.83) and Medium Sand (16.7 ± 11.84). In this context, according to the results of the residues and correlations, it was observed that A400-600 behaved in a more allusive way compared to the Nephelometric technique in drought and flood events, thus estimating the Detection Limit for CSS (26 .47 mg.L-1 and 44.67 mg.L-1) respectively.O emprego de sensores com princípios ópticos destinados a estimar o transporte de sedimentos, e principalmente a concentração de sólidos suspensos (CSS) constitui uma técnica robusta que atualmente encontra-se consolidada e bem difundida no meio científico, configurando assim uma ferramenta importante na pesquisa, gestão e controle de bacias hidrográficas.  O presente estudo realizado em um corpo hídrico presente nas proximidades da foz do Rio Coxim - (Coxim, MS), consistiu em comparar as Técnicas Nefelométricas e a área integrada da absorbância em comprimento de onda no espectro de 400 a 600 mm (A400-600) sendo estas medidas por meio de um espectrofotômetro UV/VIS para determinação indireta de CSS. Este corpo hídrico apontou características de alto aporte de sedimentos; e para efeito de possíveis relações entre os parâmetros e a caracterização dos sedimentos suspensos transportados pelo rio, foi determinada a granulometria (Areia Media, Areia Fina, Silte e Argila) das amostras processadas. As interações ocorridas dos parâmetros para determinar indiretamente CSS apresentaram as correlações: (p<0,001); Nefelométrica com (R=0,942) e A400-600 (R=0,959); e as frações granulométricas, por sua vez, apontaram: (%) de Silte (52,6 ± 17,4), além dos valores próximos de distribuição de Argila (15,3 ± 6,73), Areia Fina (15,6 ± 10,83) e Areia Média (16,7 ± 11,84). Nesse contexto, de acordo com os resultados dos resíduos e as correlações, observou-se que A400-600 se comportou de modo mais alusivo em comparação a técnica Nefelométrica nos eventos de seca e cheia, estimando desta forma o Limite de Detecção para CSS (26,47 mg.L-1 e 44,67 mg.L-1) respectivamente

Retention rate of physicians in public health administration agencies and their career paths in Japan

<p>Abstract</p> <p>Background</p> <p>Physicians who serve as public health specialists at public health centers and health departments in local or central government have significant roles because of their public health expertise. The aim of this study is to analyze the retention and career paths of such specialists in Japan.</p> <p>Method</p> <p>We analyzed the data of seven consecutive surveys, spanning 1994 to 2006. We first analyzed the 2006 survey data by sex, age group, and facility type. We then examined the changes over time in the proportion of physicians working in public health administration agencies. We also examined the distribution of the facility types and specialties in which physicians worked both before beginning and after leaving their jobs. These analyses were performed by using physician registration numbers to cross-link data from two consecutive surveys.</p> <p>Results</p> <p>The proportion of physicians working in public health administration agencies was 0.7% in 2006. The actual numbers for each survey ranged between 1,800 and 1,900. The overall rate remaining in public health administration agencies during the two-year survey interval was 72.8% for 1994-1996. The ratio declined to 67.2% for 2004-2006. Among younger physicians with 1-10 years of experience, the retention rate showed a sharp decline, dropping from 72.6% to 50.0%. Many of these physicians came from or left for a hospital position, with the proportion entering academic hospital institutions increasing in recent years. In many cases, physicians left or entered internal medicine clinical practices.</p> <p>Conclusion</p> <p>At present in Japan, the number of physicians who leave and the number who begin a position are almost the same; thus, some of the problems associated with physicians leaving are yet to become apparent. However, the fact that the retention period is shortening for younger physicians may represent a future problem for ensuring the quality of physicians in public health administration agencies. Possible strategies include: increasing the number of physicians entering positions; reducing the number leaving positions; and creating a system where physicians can easily reenter positions after leaving while also establishing a revolving door type of career development system, involving both public health departments and hospital clinical departments.</p

Cerebral malaria in children: using the retina to study the brain

Cerebral malaria is a dangerous complication of Plasmodium falciparum infection, which takes a devastating toll on children in sub-Saharan Africa. Although autopsy studies have improved understanding of cerebral malaria pathology in fatal cases, information about in vivo neurovascular pathogenesis is scarce because brain tissue is inaccessible in life. Surrogate markers may provide insight into pathogenesis and thereby facilitate clinical studies with the ultimate aim of improving the treatment and prognosis of cerebral malaria. The retina is an attractive source of potential surrogate markers for paediatric cerebral malaria because, in this condition, the retina seems to sustain microvascular damage similar to that of the brain. In paediatric cerebral malaria a combination of retinal signs correlates, in fatal cases, with the severity of brain pathology, and has diagnostic and prognostic significance. Unlike the brain, the retina is accessible to high-resolution, non-invasive imaging. We aimed to determine the extent to which paediatric malarial retinopathy reflects cerebrovascular damage by reviewing the literature to compare retinal and cerebral manifestations of retinopathy-positive paediatric cerebral malaria. We then compared retina and brain in terms of anatomical and physiological features that could help to account for similarities and differences in vascular pathology. These comparisons address the question of whether it is biologically plausible to draw conclusions about unseen cerebral vascular pathogenesis from the visible retinal vasculature in retinopathy-positive paediatric cerebral malaria. Our work addresses an important cause of death and neurodisability in sub-Saharan Africa. We critically appraise evidence for associations between retina and brain neurovasculature in health and disease, and in the process we develop new hypotheses about why these vascular beds are susceptible to sequestration of parasitized erythrocytes

Minmax robustness for multi-objective optimization problems

In real-world applications of optimization, optimal solutions are often of limited value, because disturbances of or changes to input data may diminish the quality of an optimal solution or even render it infeasible. One way to deal with uncertain input data is robust optimization, the aim of which is to find solutions which remain feasible and of good quality for all possible scenarios, i.e., realizations of the uncertain data. For single objective optimization, several definitions of robustness have been thoroughly analyzed and robust optimization methods have been developed. In this paper, we extend the concept of minmax robustness (Ben-Tal, Ghaoui, & Nemirovski, 2009) to multi-objective optimization and call this extension robust efficiency for uncertain multi-objective optimization problems. We use ingredients from robust (single objective) and (deterministic) multi-objective optimization to gain insight into the new area of robust multi-objective optimization. We analyze the new concept and discuss how robust solutions of multi-objective optimization problems may be computed. To this end, we use techniques from both robust (single objective) and (deterministic) multi-objective optimization. The new concepts are illustrated with some linear and quadratic programming instances

The robust knapsack problem with queries

We consider robust knapsack problems where item weights are uncertain. We are allowed to query an item to find its exact weight,where the number of such queries is bounded by a given parameter Q. After these queries are made, we need to pack the items robustly, i.e., so that the choice of items is feasible for every remaining possible scenario of item weights. The central question that we consider is: Which items should be queried in order to gain maximum profit? We introduce the notion of query competitiveness for strict robustness to evaluate the quality of an algorithm for this problem, and obtain lower and upper bounds on this competitiveness for interval-based uncertainty. Similar to the study of online algorithms, we study the competitiveness under different frameworks, namely we analyze the worst-case query competitiveness for deterministic algorithms, the expected query competitiveness for randomized algorithms and the average case competitiveness for known distributions of the uncertain input data. We derive theoretical bounds for these different frameworks and evaluate them experimentally. We also extend this approach to Γ-restricted uncertainties introduced by Bertsimas and Sim. Furthermore, we present heuristic algorithms for the problem. In computational experiments considering both the interval-based and the Γ-restricted uncertainty, we evaluate their empirical performance. While the usage of a Γ-restricted uncertainty improves the nominal performance of a solution (as expected), we find that the query competitiveness gets worse