Markers, Cofactors and Staging Systems in the Study of HIV Disease Progression: A Review

This paper is aimed at providing a comprehensive review of markers, cofactors and staging systems used for HIV disease, focusing on some aspects that nowadays could even be considered historical, and advancing in current issues such as the prognostic value of viral load measurements, viral genotypic and phenotypic characterization, and new HIV disease treatment protocols. CD4+ cell values, combined with the new viral markers mentioned are promising as a parsimonious predictor set for defining both severity and progression. An adequate predictor of patient resource use for planning purposes still needs to be defined

Physical properties of a rhodic haplustox under two sugarcane harvesting systems

This study had the purpose of evaluating the effects of two management types of sugarcane: harvesting of burnt cane (BCH) and mechanized harvesting of unburnt green cane (MCH), on some soil physical properties of a dystrophic Rhodic Haplustox. The data were then compared with results for the same soil type under native forest. A completely randomized design was used, with three treatments and 20 replications. The following characteristics were determined: organic matter, aggregate stability, soil bulk density, and porosity at depths of 0-0.20 m and soil penetration resistance. After 15 years of cultivation, there were some alterations in the soil under cane burnt before harvesting, evidenced by a drop in the weighted average diameter of stable aggregates in water and increased soil bulk density. Significant changes were also detected in total porosity and pore distribution under both harvesting systems. Critical values for penetration resistance were observed in the area under mechanized sugar cane harvesting, with a value of 4.5 MPa in the 40-55 cm layer. This value is considered high and could indicate compaction and restriction of root growth. Soil properties under the green cane (unburned) management system were closest to those of the soil under native forest.

Impacts of different management systems on the physical quality of an Amazonian Oxisol

The physical quality of Amazonian soils is relatively unexplored, due to the unique characteristics of these soils. The index of soil physical quality is a widely accepted measure of the structural quality of soils and has been used to specify the structural quality of some tropical soils, as for example of the Cerrado ecoregion of Brazil. The research objective was to evaluate the physical quality index of an Amazonian dystrophic Oxisol under different management systems. Soils under five managements were sampled in Paragominas, State of Pará: 1) a 20-year-old second-growth forest (Forest); 2) Brachiaria sp pasture; 3) four years of no-tillage (NT4.); 4) eight years of no-tillage (NT8); and 5) two years of conventional tillage (CT2). The soil samples were evaluated for bulk density, macro and microporosity and for soil water retention. The physical quality index of the samples was calculated and the resulting value correlated with soil organic matter, bulk density and porosity. The surface layers of all systems were more compacted than those of the forest. The physical quality of the soil was best represented by the relations of the S index to bulk density and soil organic matter.

Intercepted solar radiation by maize crops subjected to different tillage systems and water availability levels

The objective of this work was to evaluate changes in the photosynthetic photon flux density (PPFD) interception efficiency and PPFD extinction coefficient for maize crop subjected to different soil tillage systems and water availability levels. Crops were subjected to no-tillage and conventional tillage systems combined with full irrigation and non-irrigation treatments. Continuous measurements of transmitted PPFD on the soil surface and incoming PPFD over the canopy were taken throughout the crop cycle. Leaf area index and soil water potential were also measured during the whole period. Considering a mean value over the maize cycle, intercepted PPFD was higher in the conventional tillage than in the no-tillage system. During the initial stages of plants, intercepted PPFD in the conventional tillage was double the PPFD interception in the no-tillage treatment. However, those differences were reduced up to the maximum leaf area index, close to tasseling stage. The lowest interception of PPFD occurred in the conventional tillage during the reproductive period, as leaf senescence progressed. Over the entire crop cycle, the interception of PPFD by the non-irrigated plants was about 20% lower than by the irrigated plants. The no-tillage system reduced the extinction coefficient for PPFD, which may have allowed a higher penetration of solar radiation into the canopy

Phyllochron estimation in intercropped strawberry and monocrop systems in a protected environment

The phyllochron is defined as the time required for the appearance of successive leaves on a plant; this characterises plant growth, development and adaptation to the environment. To check the growth and adaptation in cultivars of strawberry grown intercropped with fig trees, it was estimated the phyllochron in these production systems and in the monocrop. The experiment was conducted in greenhouses at the University of Passo Fundo (28º15'41'' S, 52º24'45'' W and 709 m) from June 8th to September 4th, 2009; this comprised the period of transplant until the 2nd flowering. The cultivars Aromas, Camino Real, Albion, Camarosa and Ventana, which seedlings were originated from the Agrícola LLahuen Nursery in Chile, as well as Festival, Camino Real and Earlibrite, originated from the Viansa S.A. Nursery in Argentina, were grown in white polyethylene bags filled with commercial substrate (Tecnomax®) and evaluated. The treatments were arranged in a randomised block design and four replicates were performed. A linear regression was realized between the leaf number (LN) in the main crown and the accumulated thermal time (ATT). The phyllochron (degree-day leaf-1) was estimated as the inverse of the angular coefficient of the linear regression. The data were submitted to ANOVA, and when significance was observed, the means were compared using the Tukey test (p < 0.05). The mean and standard deviation of phyllochrons of strawberry cultivars intercropped with fig trees varied from 149.35ºC day leaf-1 ± 31.29 in the Albion cultivar to 86.34ºC day leaf-1 ± 34.74 in the Ventana cultivar. Significant differences were observed among cultivars produced in a soilless environment with higher values recorded for Albion (199.96ºC day leaf-1 ± 29.7), which required more degree-days to produce a leaf, while cv. Ventana (85.76ºC day leaf-1 ± 11.51) exhibited a lower phyllochron mean value. Based on these results, Albion requires more degree-days to issue a leaf as compared to cv. Ventana. It was conclude that strawberry cultivars can be grown intercropped with fig trees (cv. Roxo de Valinhos).

Weather based warning systems for bean angular-leaf-spot and anthracnose

Data available in the literature were used to develop a warning system for bean angular leaf spot and anthracnose, caused by Phaeoisariopsis griseola and Colletotrichum lindemuthianum, respectively. The model is based on favorable environmental conditions for the infectious process such as continuous leaf wetness duration and mean air temperature during this subphase of the pathogen-host relationship cycle. Equations published by DALLA PRIA (1977) showing the interactions of those two factors on the disease severity were used. Excell spreadsheet was used to calculate the leaf wetness period needed to cause different infection probabilities at different temperature ranges. These data were employed to elaborate critical period tables used to program a computerized electronic device that records leaf wetness duration and mean temperature and automatically shows the daily disease severity value (DDSV) for each disease. The model should be validated in field experiments under natural infection for which the daily disease severity sum (DDSS) should be identified as a criterion to indicate the beginning and the interval of fungicide applications to control both diseases.

Technical-economic analysis of different lighting systems for broiler poultry

ABSTRACT Broiler poultry is highly dependent on artificial lightening. Power consumption costs of artificial lighting systems is the second largest expense related to broiler industry, second only to feed expenses. Therefore, the current study focused to analyze technical and economic feasibility of replacing incandescent lamps already used in aviaries with other lamp types. Costs related to power consumption, implementation and maintenance of the lighting systems were evaluated with the aid of financial mathematics using net present value, return over investment and payback. Systems composed of six lamp types were analyzed in two different configurations to meet the minimum illuminance of 5 and 20 lux and for use in conventional sheds and dark house. The lamps tested were incandescent (LI) of 100 W, compact fluorescent (CFL) of 34 W, mixed (ML) 160 W sodium vapor (SVL) of 70 W, tubular fluorescent T8 (TFL T8) of 40 W and tubular fluorescent T5 (TFL T5) of 28 W. For the systems tested, it was found that the tubular fluorescent lamps T8 and T5 showed the best results of technical and economic feasibility.

Effect of long-term agricultural management systems on occurrence and composition of weed species

This study aims to assess the composition of weed communities as a function of distinct selection factors, at neighboring areas submitted to distinct soil management and diverse use for sixteen years. Four areas submitted to distinct managements (conventional tillage system; no-till system; integration crop/livestock and continuous livestock) were sampled in relation to the occurrence and severity of weed species by the beginning of the planting season, being estimated the relative abundance, relative frequency and relative dominance of each weed species under each area, as well as the Importance Value Index for each species. Areas were also compared by the Sørensen's similarity coefficient. Areas where pasture and grazing were never present, exhibited a number of seedlings of weed species 250% higher than areas periodically or continuously under grazing, while the area of soil covered by weeds was 87% superior at the conventional tillage system in relation to the average of the other treatments. Grass weeds were the most important at the conventional tillage area while broadleaved weeds where more important at the no-till area, probably due also to herbicide selection factors. Under crop/livestock integration there may be the need to care about controlling seedlings of the forage species inside grain crops in succession.

Occurrence of weed species in Jatropha curcas intercropping systems

This study aimed to evaluate the level of infestation by weed species in a consolidated Jatropha plantation, as a function of the plant species grown in interrows. The experiment was installed in 2006 at the district of Itahum, city of Dourados, state of Mato Grosso do Sul, Brazil, made possible through a partnership between Embrapa Western Agriculture and Paraiso Farm. Treatments consisted of (1) Jatropha in monocrop, with no plant at the interrrows; or the following plants cultivaded at the interrows of Jatropha: (2) Stylosanthes spp.; (3) Brachiaria ruziziensis; (4) Brachiaria ruziziensis + Stylosanthess pp.; (5) Brachiaria humidicola; (6) Panicum maximum cv. massai; (7) Cajanus cajan cv. anão; (8) Crotalaria spectabilis; (9) Crop rotation system 1 - (maize second crop -Crambe abyssinica - soybean - peanut); and (10) Crop rotation system 2 - (cowpea - radish - maize - cowpea) conducted for two years. Phytosociological characterization of weed species was accomplished in 2011 based on the Ecological Approach. Estimations of relative abundance, frequency, dominance and Importance Value Index were obtained. Areas were also characterized by the diversity coefficients of Simpson and modified Shannon-Weiner, and then grouped by cluster analysis. Areas with low soil coverage resulted in higher infestation levels; crop rotation in the interrows of Jatropha produced a significant reduction in weed infestation, but the lowest infestation levels were observed when grasses were grown intercropped with Jatropha. Lower diversity coefficients were associated with occurrence of the most troublesome weed species. In the first years after planting Jatropha, species of Brachiaria or a crop rotation involving species with high mulching ability and whose biomass exhibit a high C:N ratio, should be established in the interrows to avoid problems with weeds infestation.

Further analysis of open-respirometry systems: an a-compartmental mechanistic approach

A system is said to be "instantaneous" when for a given constant input an equilibrium output is obtained after a while. In the meantime, the output is changing from its initial value towards the equilibrium one. This is the transient period of the system and transients are important features of open-respirometry systems. During transients, one cannot compute the input amplitude directly from the output. The existing models (e.g., first or second order dynamics) cannot account for many of the features observed in real open-respirometry systems, such as time lag. Also, these models do not explain what should be expected when a system is speeded up or slowed down. The purpose of the present study was to develop a mechanistic approach to the dynamics of open-respirometry systems, employing basic thermodynamic concepts. It is demonstrated that all the main relevant features of the output dynamics are due to and can be adequately explained by a distribution of apparent velocities within the set of molecules travelling along the system. The importance of the rate at which the molecules leave the sensor is explored for the first time. The study approaches the difference in calibrating a system with a continuous input and with a "unit impulse": the former truly reveals the dynamics of the system while the latter represents the first derivative (in time) of the former and, thus, cannot adequately be employed in the apparent time-constant determination. Also, we demonstrate why the apparent order of the output changes with volume or flow.