Approximating a class of combinatorial problems with rational objective function

In the late seventies, Megiddo proposed a way to use an algorithm for the problem of minimizing a linear function a(0) + a(1)x(1) + ... + a(n)x(n) subject to certain constraints to solve the problem of minimizing a rational function of the form (a(0) + a(1)x(1) + ... + a(n)x(n))/(b(0) + b(1)x(1) + ... + b(n)x(n)) subject to the same set of constraints, assuming that the denominator is always positive. Using a rather strong assumption, Hashizume et al. extended Megiddo`s result to include approximation algorithms. Their assumption essentially asks for the existence of good approximation algorithms for optimization problems with possibly negative coefficients in the (linear) objective function, which is rather unusual for most combinatorial problems. In this paper, we present an alternative extension of Megiddo`s result for approximations that avoids this issue and applies to a large class of optimization problems. Specifically, we show that, if there is an alpha-approximation for the problem of minimizing a nonnegative linear function subject to constraints satisfying a certain increasing property then there is an alpha-approximation (1 1/alpha-approximation) for the problem of minimizing (maximizing) a nonnegative rational function subject to the same constraints. Our framework applies to covering problems and network design problems, among others.

Influência de diferentes materiais de cobertura no conforto térmico de instalações para frangos de corte no oeste paulista

Este trabalho apresenta um estudo da influência de diferentes materiais de cobertura no conforto térmico de instalações destinadas à criação de frangos de corte. A pesquisa foi desenvolvida no Câmpus Experimental da UNESP de Dracena - SP. Quatro protótipos em escala real foram construídos, com área de 28 m² cada, cobertos com telha reciclada à base de embalagens longa vida, telha cerâmica, telha cerâmica pintada de branco e telha de fibrocimento. Os dados foram coletados durante o período de inverno de 2007, totalizando 90 dias. Com esses dados, foram calculados os índices de conforto térmico Carga Térmica Radiante (CTR) e a variável ambiental (Ta). Uma análise estatística por inferência e descritiva foi realizada com os valores do índice de conforto térmico e da variável ambiental. Com os resultados obtidos, é possível afirmar que a telha reciclada apresentou índices de conforto térmico semelhantes àqueles encontrados para as telhas cerâmicas. O protótipo coberto com telha de fibrocimento apresentou os maiores índices, e o coberto com telha cerâmica branca, os menores índices de conforto térmico. No entanto para o período de inverno e para os horários avaliados, todas as instalações apresentaram índices de conforto térmico fora da zona de termoneutralidade do frango de corte.

The Southern Brazilian shelf: general characteristics, quaternary evolution and sediment distribution

Extending from latitude 34ºS to 22ºS the Southern Brazilian shelf constitutes the only part of the Brazilian shelf with a subtropical to temperate environment. The studies on the different geological aspects of the area began in the 1960's and have recently been reassessed after studies related to the determination of the Economic Exclusive Zone. In terms of morphology, the Southern Brazilian shelf may be divided into three sectors, the São Paulo Bight, the Florianópolis-Mostardas Sector and the Rio Grande Cone, characterized by conspicuous differences in terms of geological determining factors, bathymetry, declivities and the presence of canyons and channels. Despite the existence of hundreds of radiocarbon datings the sea level changes curve of southern Brazil during the Last Glacial Cycle is still a matter of debate. A recent controversy on the Middle and late Holocene sea level changes curve raised the question of the amplitude of the oscillations which occurred in the period. Also, a few but relatively consistent radiocarbon datings suggest the occurrence of a high sea level during Isotope Stage 3. In terms of sedimentary cover the Southern Brazilian shelf exhibits a very strong hydrodynamic control, both latitudinal and bathymetrical. The sector southward from 25ºS is characterized by the influence of the plume of water carrying sediments originating from the Río de La Plata. Actually its presence is conspicuous up to 28ºS, with the area between this latitude and 25ºS constituting a transitional zone. In terms of bathymetry the outer shelf is marked by the "floor-polisher" effect of the Brazil Current, which is responsible for the maintenance of a relict facies in areas deeper than 100 meters.

INFLUENCE OF ROOF MATERIAL ON THERMAL COMFORT IN BROILER HOUSINGS IN THE STATE OF SAO PAULO

This paper presents a different roof tiles influence study on the thermal comfort for broiler housings. The research was conducted at UNESP`s Experimental Campus at Dracena, state of Sao Paulo, Brazil. Four prototypes in real scale were built, each with an area of 28 m(2). The prototype was covered with roof tiles made of recycled long-life packing material, ceramic tiles, ceramic tiles painted with white coating, and fiber/cement tiles. Temperatures inside the structures were recorded in the winter 2007 over a 90-day period. The results obtained indicated that recycled tile thermal behavior was similar to ceramic tiles. However for the winter period all the prototypes had presented comfort thermal index not in the broilers thermo neutral zone.

EVALUATION OF FIVE SUGAR CANE PLANTERS

Brazil is the world biggest producer of sugar cane with an area of 7x10(6) hectares. Mainly the system used for planting is the semi-mechanized one, which consists in opening the furrows with a machine, manually allocating the fractioned stalks and then covering the furrows done by the machines. The great amount of human labor used in the semi-mechanized system is becoming harder to find and also more expensive, indicating the need of a fully mechanized operation. Currently in Brazil these agriculture machines industries offers six different types of fully mechanized sugar cane planters (two types of whole stalks for planting and four using mechanized harvested stalks known as billets). All of them plant in two furrows simultaneously in 1.5 m row spacing. This study analyzed five different machines and the following variables: Working Speed (km h(-1)); Effective Capacity (ha h(-1)), Drawbar Force (kgf), Draw Bar Power (in HP), Fuel Consumption (L h(-1)) and Costs (US$ ha(-1)) comparing them with the semi-mechanized system. This research also characterized the stalks for planting as viable gems number (%), non viable gems number (%) and billet length (m). And lastly the mechanized planting system is cheaper than the conventional one and none of the machines has an adequate mechanism for placing the right amount of sugar cane seed.

Microvascular Lymphatic Density Analysis in Cutaneous Regressive and Nonregressive Superficial Spreading Melanomas Using the Lymphatic Marker D2-40

Background: The prognostic significance of spontaneous regression in melanoma, especially thin lesions, has been a controversial issue for the past 20 years, although recent studies suggest that extensive and late regression may be related to worse prognosis. Many data suggest that lymphangiogenesis predicts metastatic spread in melanoma. Methods: We have quantified lymphatic microvascular density (LMVD) in thin (<= 1.0 mm) superficial spreading melanomas comparing regressive and nonregressive melanomas, regressive and nonregressive areas from the same tumor, and early and late histological stages of regression in the same tumor. In addition, we tried to correlate lymphangiogenesis and tumor growth phase. We conducted histological examinations and immunohistochemical analyses using monoclonal antibody D2-40 with subsequent quantification by image analysis of 37 melanomas, 16 regressive and 21 nonregressive (controls). Results: We found higher LMVD in the late stage of regression compared with nonregressive area (internal control) of regressive melanomas. Conclusions: Our study suggest that the late stage of spontaneous regression in thin melanomas may be related to worse prognosis as it showed higher LMVD, and evidence shows that this is related with increased risk of metastatic spread. But this supposition must be confirmed by a longer follow-up for detection of lymph node metastases.

THE SOUTHERN BRAZILIAN SHELF: GENERAL CHARACTERISTICS, QUATERNARY EVOLUTION AND SEDIMENT DISTRIBUTION

Extending from latitude 34 degrees S to 22 degrees S the Southern Brazilian shelf constitutes the only part of the Brazilian shelf with a subtropical to temperate environment. The studies on the different geological aspects of the area began in the 1960`s and have recently been reassessed after studies related to the determination of the Economic Exclusive Zone. In terms of morphology, the Southern Brazilian shelf may be divided into three sectors, the Sao Paulo Bight, the Florianopolis-Mostardas Sector and the Rio Grande Cone, characterized by conspicuous differences in terms of geological determining factors, bathymetry, declivities and the presence of canyons and channels. Despite the existence of hundreds of radiocarbon datings the sea level changes curve of southern Brazil during the Last Glacial Cycle is still a matter of debate. A recent controversy on the Middle and late Holocene sea level changes curve raised the question of the amplitude of the oscillations which occurred in the period. Also, a few but relatively consistent radiocarbon datings suggest the occurrence of a high sea level during Isotope Stage 3. In terms of sedimentary cover the Southern Brazilian shelf exhibits a very strong hydrodynamic control, both latitudinal and bathymetrical. The sector southward from 25 degrees S is characterized by the influence of the plume of water carrying sediments originating from the Rio de La Plata. Actually its presence is conspicuous up to 28 degrees S, with the area between this latitude and 25 degrees S constituting a transitional zone. In terms of bathymetry the outer shelf is marked by the ""floor-polisher"" effect of the Brazil Current, which is responsible for the maintenance of a relict facies in areas deeper than 100 meters.

Surface and subterranean ichthyofauna in the Serra do Ramalho karst area, northeastern Brazil, with updated lists of Brazilian troglobitic and troglophilic fishes

After an ichthyofaunistic survey in several epigean (surface) water bodies of the Serra do Ramalho, southern Bahia, conducted in May 2007, 44 species were recorded; in addition, three non-troglomorphic (normally eyed and pigmented) and two troglomorphic species were recorded only in caves, totaling 49 species of fishes for the area, which represents a little more than one fourth of the total registered in the literature for the entire Rio São Francisco basin. In these caves, which have been studied since 2005, eight non-troglomorphic species were sampled and their presence in both epigean and subterranean habitats, associated to the lack of morphological differences, indicate that they may be either troglophiles (species encompassing individuals able to live and complete their life cycle either in the surface or in the subterranean environment), trogloxenes (individuals regularly found in subterranean habitats, but which must return periodically to the surface in order to complete their life cycle) or even accidental in caves. In addition, two troglomorphic species (with reduced eyes and melanic pigmentation when compared to close epigean relatives), belonging respectively to the genera Rhamdia and Trichomycterus, were recorded exclusively in caves, thus classified as troglobites. Interestingly, no epigean representative of the genus Trichomycterus was collected. The new data are integrated into updated lists of Brazilian troglobitic and troglophilic fishes, based on published data and new records recently confirmed.

Biotin-avidin sandwich elisa with specific human isotypes IgG1 and IgG4 for Culicidae mosquito blood meal identification from an epizootic yellow fever area in Brazil

With a view toward investigating the feeding behavior of Culicidae mosquitoes from an area of epizootic yellow fever transmission in the municipalities of Garruchos and Santo Antônio das Missões, Rio Grande do Sul State, Brazil, specimens were collected by aspiration from September 2005 to April 2007. The engorged females were submitted to blood meal identification by enzyme-linked immunosorbent assay (ELISA). A total of 142 blood-engorged samples were examined for human or monkey blood through species-specific IgG. Additional tests for specificity utilizing isotypes IgG1 and IgG4 of human monoclonal antibodies showed that only anti-human IgG1 was effective in recognizing blood meals of human origin. The results indicated a significant difference (p = 0.027) in detection patterns in samples of Haemagogus leucocelaenus recorded from human blood meals at Santo Antônio das Missões, which suggests some degree of exposure, since it was an area where epizootic outbreaks have been reported.

Sand fly captures with Disney traps in area of occurrence of Leishmania (Leishmania) amazonensis in the state of Mato Grosso do Sul, mid-western Brazil

INTRODUCTION: The work was conducted to study phlebotomine fauna (Diptera: Psychodidae) and aspects of American cutaneous leishmaniasis transmission in a forested area where Leishmania (Leishmania) amazonensis occurs, situated in the municipality of Bela Vista, State of Mato Grosso do Sul, Brazil. METHODS: The captures were conducted with modified Disney traps, using hamster (Mesocricetus auratus) as bait, from May 2004 to January 2006. RESULTS: Ten species of phlebotomine sandflies were captured: Brumptomyia avellari, Brumptomyia brumpti, Bichromomyia flaviscutellata, Evandromyia bourrouli, Evandromyia lenti, Lutzomyia longipalpis, Psathyromyia campograndensis, Psathyromyia punctigeniculata, Psathyromyia shannoni and Sciopemyia sordellii. The two predominant species were Ev bourrouli (57.3%) and Bi flaviscutellata (41.4%), present at all sampling sites. Two of the 36 hamsters used as bait presented natural infection with Leishmania. The parasite was identified as Leishmania (Leishmania) amazonensis. CONCLUSIONS: Analysis of the results revealed the efficiency of Disney traps for capturing Bichromomyia flaviscutellata and the simultaneous presence of both vector and the Leishmania species transmitted by the same can be considered a predictive factor of the occurrence of leishmaniasis outbreaks for the human population that occupies the location.

Entomological characterization and natural infection of anophelines in an area of the Atlantic Forest with autochthonous malaria cases in mountainous region of Espírito Santo State, Brazil

No Espírito Santo, os casos de malária autóctone estão distribuídos na região serrana próximo aos fragmentos de Mata Atlântica. Uma vez que alguns aspectos da doença são obscuros, a detecção das possíveis espécies de vetores pode auxiliar na elucidação de incertezas epidemiológicas. Estudos entomológicos e de infecção natural foram realizados com anofelinos (Diptera: Culicidae) capturados no município de Santa Tereza, ES. Capturas mensais foram realizadas de março de 2004 a fevereiro de 2006. Armadilhas CDC-CO2 foram utilizadas do crepúsculo (18:00h) ao amanhecer (6:00h), para capturar anofelinos nos seguintes habitats: próximo ao domicílio e área aberta (solo), margem e interior da mata (solo e copa). Armadilhas Shannon também foram utilizadas nos mesmos locais que as de CDC-CO2. Capturou-se o total de 2.290 anofelinos distribuídos em 10 espécies. A maior frequência relativa foi de Anopheles (Kerteszia) cruzii Dyar & Knab / A.(K.) homunculus Komp, sendo a maioria capturada em CDC-CO2 instalada na copa da mata. A principal espécie capturada em armadilha Shannon foi A.(Nyssorhynchus) strodei Root. O maior número de anofelinos foi capturado entre julho e setembro das 18:00h às 22:00h. Provavelmente A.(K.) cruzii é responsável pela transmissão da malária dentro ou próximo aos fragmentos de Mata Atlântica. Entretanto, a participação de outras espécies não pode ser ignorada, visto que 53 por cento da amostragem foi constituída pelo subgênero Nyssorhynchus. A detecção de Plasmodium vivax no tórax de A. cruzii, A. parvus (Chagas) e A. galvaoi Causey, Deane & Deane por meio de PCR reforça esse argumento

Fruit flies (Diptera, Tephritidae) and their associations with native host plants in a remnant area of the highly endangered Atlantic Rain Forest in the State of Espirito Santo, Brazil

The results presented in this paper refer to a host survey, lasting approximately three and a half years (February 2003-july 2006), undertaken in the Vale do Rio Doce Natural Reserve, a remnant area of the highly endangered Atlantic Rain Forest located in Linhares County, State of Espirito Santo, Brazil. A total of 330 fruit samples were collected from native plants, representing 248 species and 51 plant families. Myrtaceae was the most diverse family with 54 sampled species. Twenty-eight plant species, from ten families, are hosts of ten Anastrepha species and of Ceratitis capitata (Wiedemann). Among 33 associations between host plants and fruit flies, 20 constitute new records, including the records of host plants for A. fumipennis Lima and A. nascimentoi Zucchi. The findings were discussed in the light of their implications for rain forest conservation efforts and the study of evolutionary relationships between fruit flies and their hosts.

Leaf area index estimation with MODIS reflectance time series and model inversion during full rotations of Eucalyptus plantations

The leaf area index (LAI) of fast-growing Eucalyptus plantations is highly dynamic both seasonally and interannually, and is spatially variable depending on pedo-climatic conditions. LAI is very important in determining the carbon and water balance of a stand, but is difficult to measure during a complete stand rotation and at large scales. Remote-sensing methods allowing the retrieval of LAI time series with accuracy and precision are therefore necessary. Here, we tested two methods for LAI estimation from MODIS 250m resolution red and near-infrared (NIR) reflectance time series. The first method involved the inversion of a coupled model of leaf reflectance and transmittance (PROSPECT4), soil reflectance (SOILSPECT) and canopy radiative transfer (4SAIL2). Model parameters other than the LAI were either fixed to measured constant values, or allowed to vary seasonally and/or with stand age according to trends observed in field measurements. The LAI was assumed to vary throughout the rotation following a series of alternately increasing and decreasing sigmoid curves. The parameters of each sigmoid curve that allowed the best fit of simulated canopy reflectance to MODIS red and NIR reflectance data were obtained by minimization techniques. The second method was based on a linear relationship between the LAI and values of the GEneralized Soil Adjusted Vegetation Index (GESAVI), which was calibrated using destructive LAI measurements made at two seasons, on Eucalyptus stands of different ages and productivity levels. The ability of each approach to reproduce field-measured LAI values was assessed, and uncertainty on results and parameter sensitivities were examined. Both methods offered a good fit between measured and estimated LAI (R(2) = 0.80 and R(2) = 0.62 for model inversion and GESAVI-based methods, respectively), but the GESAVI-based method overestimated the LAI at young ages. (C) 2010 Elsevier Inc. All rights reserved.

Decrease in Mycobacterium tuberculosis specific immune responses in patients with untreated psoriasis living in a tuberculosis endemic area

Tuberculosis has emerged as a major concern in patients with immuno-mediated diseases, including psoriasis, undergoing treatment with biologicals. However, it is not known whether the chronically activated immune system of psoriasis patients interferes with their Mycobacterium tuberculosis (Mtb)-specific immunity, especially in tuberculosis-endemic areas like Brazil. We evaluated T-cell responses to a Mtb lysate and to the recombinant Mtb proteins ESAT-6 and Ag85B of tuberculin skin test (TST) positive and TST negative patients with severe or mild/moderate, untreated psoriasis in three different assays: lymphocyte proliferation, enzyme immunoassay for interferon (IFN)-gamma and interleukin (IL)-10 production by peripheral blood mononuclear cells and overnight enzyme immunospot (ELISpot) for enumerating IFN-gamma-secreting cells. In our cohort, a low proportion (29%) of the severe psoriasis patients tested were TST-positive. IFN-gamma and IL-10 secretion and T-cell proliferation to Mtb antigens were reduced in TST-negative but not in TST-positive patients with severe psoriasis when compared to healthy controls with the same TST status. Similarly, severe psoriasis patients had decreased cytokine secretion and proliferative response to phytohemagglutinin. However, most psoriasis patients and healthy controls showed detectable numbers of IFN-gamma-secreting effector-memory T-cells in response to Mtb antigens by ELISpot. TST-negative, mild/moderate psoriasis patients had responses that were mostly intermediary between TST-negative controls and severe psoriasis patients. Thus, patients with severe psoriasis possess decreased anti-Mtb central memory T-cell responses, which may lead to false-negative results in the diagnosis of TB infection, but retain T-cell memory-effector activity against Mtb antigens. We hypothesize that the latter may confer some protection against tuberculosis reactivation.

Diminished CD4+/CD25+T cell and increased IFN-gamma levels occur in dogs vaccinated with Leishmune (R) in an endemic area for visceral leishmaniasis

The Leishmune (R) vaccine has been used in endemic areas to prevent canine visceral leishmaniasis in Brazil, but cytokine production induced by vaccination has rarely been investigated in dogs. This study aimed to evaluate the immune response of dogs vaccinated with Leishmune FML vaccine (Fort Dodge) against total antigen of Leishmania (Leishmania) chagasi (TAg) and FML. Twenty healthy dogs from Aracatuba, Sao Paulo, Brazil, an endemic leishmaniasis area, received three consecutive subcutaneous injection of Leishmune vaccine at 21-day intervals. PBMC were isolated before and 10 days after completing vaccination and lymphoproliferative response and antibody production against FML or total promastigote antigen were tested. Cytokines IFN-gamma, IL-4 and TNF-alpha were measured in culture supernatant and CD4+/CD25+ and CD8+/CD25+ T cell presence was determined. Analysis of the data indicated that the vaccine conferred humoral responses (100%) against both antigens and cellular immunity to FML (85%) and total antigen (80%), the supernatant of cultured cells stimulated with TAg and FML showed an increase in IFN-gamma (P < 0.05), and the vaccine reduced CD4+/CD25+ T cell presence compared to that observed before vaccination. These responses may constitute part of the immune mechanism induced by Leishmune. (C) 2010 Elsevier B.V. All rights reserved.