Contact melting of a three-dimensional phase change material on a flat substrate

In this paper a model is developed to describe the three dimensional contact melting process of a cuboid on a heated surface. The mathematical description involves two heat equations (one in the solid and one in the melt), the Navier-Stokes equations for the flow in the melt, a Stefan condition at the phase change interface and a force balance between the weight of the solid and the countering pressure in the melt. In the solid an optimised heat balance integral method is used to approximate the temperature. In the liquid the small aspect ratio allows the Navier-Stokes and heat equations to be simplified considerably so that the liquid pressure may be determined using an igenfunction expansion and finally the problem is reduced to solving three first order ordinary differential equations. Results are presented showing the evolution of the melting process. Further reductions to the system are made to provide simple guidelines concerning the process. Comparison of the solutions with experimental data on the melting of n-octadecane shows excellent agreement.

Lymphatic Filariasis in Brazilian Urban Area (Maceió, Alagoas)

A cross-sectional survey conducted among evening students was used to determine the prevalence of Wuchereria bancrofti infection in Maceió, capital of the State of Alagoas, northeast Brazil. A single thick-blood smear was used, being collected between 10 p.m. and 12 a.m. From a total of 29,551 students enrolled at evening elementary schools in the 33 city sectors, 16,569 (56.4%) were random selected for inclusion in the study. From those, 10,857 (65.5%) were interviewed and examined and 73 (0.7%) were found to have microfilaraemia. Autochthonous W. bancrofti carriers live in 10 of the 33 city sectors, suggesting a focal distribution. Moreover, 84% of infections were diagnosed among 29% of all students examined, inhabiting three contiguous sectors at the city central area, presenting infection rates up to 5.3%. Students living in city sectors with prevalence of microfilariae carriers greater than 1% were found to have a higher risk for infection when compared to students from the rest of the town [Relative Odds (RO) 12.8, 95% CI 6.7 - 25.1]. Eleven positive individuals from non endemic areas were living in Maceió for more than 10 years; time of residence in the area was a major risk factor for infection among students not born in the region (p<0.01). Regarding sex, male students presented a higher proportion of positive (RO 1.7, 95% CI 1.1 - 2.9).

Microgeographical patterns of schistosomiasis and water contact behavior; examples from Africa and Brazil

This paper examines the results of spatial (microgeographical) water contact/schistosomiasis studies in two African (Egyptian and Kenyan) and one Brazilian communities. All three studies used traditional cartographic and statistical methods but one of them emploeyd also GIS (geographical information systems) tools. The advantage of GIS and their potential role in schistosomiasis control are briefly described. The three cases revealed considerable variation in the spatial distribution of water contact, transmission parameters and infection levels at the household and individual levels. All studies showed considerable variation in the prevalence and intensity of infection between households. They also show a variable influence of distance on water contact behavior associated with type of activity, age, sex, socioeconomic level, perception of water quality, season and availability of water in the home. Water contact behavior and schistosomiasis were evaluated in the Brazilian village of Nova União within the context of water sharing between household and age/sex groups. Recommendations are made for further spatial studies on the transmission and control of schistosomiasis.

Chronic carriers of hepatitis B surface antigen in an endemic area for schistosomiasis mansoni in Brazil

Data on the association of schistosomiasis and hepatitis B in field-based studies are scarce. Two areas have been selected for this study: i) Queixadinha, endemic for schistosomiasis, with a population of 693 individuals, and ii) Capão, a control non-endemic area, with 515 inhabitants. Sera of all individuals in both areas were tested for hepatitis B infection, yearly, from 1994 to 1997. In the first area hepatitis B was found in 32.1% of children up to one year old and reached a peak of 68.7% in the age range of 15 to 19 years. In the control area the prevalence of hepatitis B was under 5% up to 19 years of age and the highest prevalence was observed in adults over 45. HBsAg was detected in 9.4% of the individuals living in the endemic area for schistosomiasis and in 1.4% of the controls (OR=4.98; 95%CI=3.7-6.7). The index of chronicity of HBsAg was not statistically different in the studied areas (8.1% x 7.3%; OR = 1.09; 95%CI= 0.42-3.03), nor was it different for people with and without schistosomiasis in Queixadinha (8.7% x 7.0%). We conclude that the Schistosoma mansoni infection has not altered the course of hepatitis B in the studied area.

Schistosomiasis control based on repeated chemotherapy in a rural village of the sugar-cane zone in Northeast Brazil

A schedule of repeated chemotherapy with oxamniquine, consisting of biannual treatment of school-aged (7-13 years) children and annual treatment of all other age groups, was used in a representative rural village from a highly endemic area of schistosomiasis in Pernambuco. Significant reductions in infection were obtained only after two cycles of treatment, as the overall prevalence decreased from 72.6% to 41.7% and the geometric mean egg counts per gram of faeces among positives fell from 188.4 to 76. In a school-aged cohort (n=29) three treatments at six-month intervals were necessary to significantly reduce the proportion of positives (from 75.9% to 51.7%). In a cohort of children under 7 years of age (n=20) the proportion of positives actually increased (from 30% to 45%) despite two annual treatments. Water contact was intense and host snail density was relatively high. As there is no short-term perspective of improved sanitation, auxiliary measures such as focal mollusciciding are needed for an adequate control of schistosomiasis in this and alike areas.

A comparative study on IgG-ELISA, IgM-IFT and Kato-Katz methods for epidemiological purposes in a low endemic area for schistosomiasis

The high sensitivity and the possibility of automation of the enzyme-linked-immunosorbent-assay (ELISA) has indicated this technique as one of the most useful serological test for epidemiological studies. In the present study, an ELISA for detection of IgG antibodies against adult worm antigens (IgG-ELISA) was investigated for epidemiological purposes, in a rural area of the municipality of Itariri (São Paulo, Brazil). Blood on filter paper (1,180 samples) from about 650 schoolchildren were submitted to ELISA and the data compared to the results of the parasitological method of Kato-Katz and also to the IgM-IFT (immunofluorescence test for IgM antibodies to gut associated antigens). The prevalence rates respectively of 8.5%, 43.0%, and 56.2% by the Kato-Katz, IgG-ELISA, and IgM-IFT methods suggest the poor sensitivity of the parasitological method for detection of Schistosoma mansoni eggs in individuals with low worm burden, situation commonly observed in low endemic areas. These results can partially explain the poor degree of agreement between the IgG-ELISA and the Kato-Katz, as suggested by the Kappa index of 0.170. Otherwise, the Kappa index of 0.675 showed substantial agreement between the two serological tests. Some discrepancy of results between the two serological techniques must be better investigated.

Comparative Analysis by Polymerase Chain Reaction Amplified Minicircles of Kinetoplast DNA of a Stable Strain of Trypanosoma cruzi from São Felipe, Bahia, its Clones and Subclones: Possibility of Predominance of a Principal Clone in this Area

Molecular characterization of one stable strain of Trypanosoma cruzi, the 21 SF, representative of the pattern of strains isolated from the endemic area of São Felipe, State of Bahia, Brazil, maintained for 15 years in laboratory by serial passages in mice and classified as biodeme Type II and zymodeme 2 has been investigated. The kinetoplast DNA (kDNA) of parental strain, 5 clones and 14 subclones were analyzed. Schizodeme was established by comparative study of the fragments obtained from digestion of the 330-bp fragments amplified by polymerase chain reaction (PCR) from the variable regions of the minicicles, and digested by restriction endonucleases Rsa I and Hinf I. Our results show a high percentual of similarity between the restriction fragment lenght polymorphism (RFLP) for the parental strain and its clones and among these individual clones and their subclones at a level of 80 to 100%.This homology indicates a predominance of the same "principal clone" in the 21SF strain and confirms the homogeneity previously observed at biological and isozymic analysis. These results suggest the possibility that the T. cruzi strains with similar biological and isoenzymic patterns, circulating in this endemic area, are representative of one dominant clone. The presence of "principal clones" could be responsible for a predominant tropism of the parasites for specific organs and tissues and this could contribute to the pattern of clinico-pathological manifestations of Chagas's disease in one geographical area.

Distribution of Sandflies (Diptera:Psychodidae) on Tree-trunks in a Non-flooded Area of the Ducke Forest Reserve, Manaus, AM, Brazil

Sandflies were collected in the base of tree-trunks in the seasons of high and least rainfall in the Ducke Forest Reserve, near Manaus in the State of Amazonas. Lutzomyia umbratilis was the most abundant sandfly species. Caryocar villosum, Chrysophyllum amazonicum, Dinizia excelsa, Eschweilera atropetiolata and Parkia multijuga were the tree species on which most sandflies were collected and relative abundance were related to trunk characteristics. Seasonal patterns of sandfly distribution in the forest were observed.

Contact and communication with healthcare providers regarding influenza vaccination during the 2009-2010 H1N1 pandemic.

Objective. The existence of two vaccines seasonal and pandemic-created the potential for confusion and misinformation among consumers during the 2009-2010 vaccination season. We measured the frequency and nature of influenza vaccination communication between healthcare providers and adults for both seasonal and 2009 influenza A(H1N1) vaccination and quantified its association with uptake of the two vaccines.Methods. We analyzed data from 4040 U.S. adult members of a nationally representative online panel surveyed between March 4th and March 24th, 2010. We estimated prevalence rates and adjusted associations between vaccine uptake and vaccination-related communication between patients and healthcare providers using bivariate probit models.Results. 64.1% (95%-CI: 61.5%-66.6%) of adults did not receive any provider-issued influenza vaccination recommendation. Adults who received a provider-issued vaccination recommendation were 14.1 (95%-CI: -2.4 to 30.6) to 32.1 (95%-CI: 24.3-39.8) percentage points more likely to be vaccinated for influenza than adults without a provider recommendation, after adjusting for other characteristics associated with vaccination.Conclusions. Influenza vaccination communication between healthcare providers and adults was relatively uncommon during the 2009-2010 pandemic. Increased communication could significantly enhance influenza vaccination rates. (C) 2011 Elsevier Inc. All rights reserved.

Density of Sand Flies (Diptera: Psychodidae) in Domestic and Wild Animal Shelters in an Area of Visceral Leishmaniasis in the State of Rio Grande do Norte, Brazil

The objective of the present study was to determine the association of sand flies with the presence of domestic and wild animals in the peridomiciliary area. The sand flies were collected using direct aspiration and CDC light traps placed in animal shelters. The results suggest that different sand flies species have different behavioral characteristics in an apparent preference for animal baits and that Lutzomyia longipalpis and Lu. evandroi were the most eclectic species regarding their biotope choice. Lu. longipalpis showed a distinct preference for horses and Lu. evandroi for armadillos.