Search

This paper examines the livelihood strategies (LS) of two ethnic groups and explores their implications for forest conservation. We used data from household and community surveys covering migrant colonists and indigenous (Kichwa) people in the Sumaco Biosphere Reserve (SBR) in the central northern Ecuadorian Amazon. Data were collected using the Poverty and Environment Network methodology of the Center for International Forestry Research (CIFOR-PEN). To estimate LS, income proportions of farm portfolios were used in a Principal Components Analysis (PCA) followed by an Agglomerative Hierarchical Clustering (AHC). The results identify four LS based on: forest income, crop production, livestock production and wage labour (off-farm income). The results of a multinomial logit model (MLM) showed that ethnicity has strong influence on their choice of LS, and households with higher physical asset holdings are more likely to engage in more remunerative LS in both ethnicities. Tobit regression show that the ethnic group of Kichwa has US$ 223 higher annual income from Crop-based LS in comparison to colonists. In contrast, colonists earn, on average, US$ 472 per year more from livestock than indigenous households in livestock-based LS and 182 dollars annually more in wage-based LS. Households with greater human capital are more engaged in Wage labour-based LS. Interestingly, residing within the buffer zone of the SBR reduces forest income by US$ 268 in Forest-based LS. The relative remaining forest land is not significantly related to LS. Potential implications of the different activities and composition of household assets in each LS are discussed in order to draw conclusions for equitable development and forest conservation.

Sugarcane orange rust caused by Puccinia kuehnii has recently become an important disease in sugarcane crops and its spread is causing great concern to growers. In this study, we analyzed spores from symptomatic orange rust sugarcane leaves collected in multiple locations in Cuba in a 4-year-period in order to characterize morphological traits of P. kuehnii, establish an adequate molecular technique to characterize it, and determine its infection court in sugarcane. Orange rust caused by P. kuehnii was confirmed by polymerase chain reaction (PCR) and morphological characterization. AFLP markers detected high diversity in P. kuenhnii samples. Sequencing of rDNA regions, as expected, did not reveal differences and SSR markers designed for P. melanocephala could not be transferred to P. kuehnii. In addition to stomata, entry through prickles was also detected as a new infection court in sugarcane. Although the presence of pustules on the adaxial leaf surface was frequently detected, no clear correlation between this presence and density of stomata and/or prickles was found.

In humid tropical zones of Mexico maize (Zea mays L.) is an important crop in human and animal feed. Six maize genotypes were studied to evaluate grain and leaf production, under three plant densities (50,000; 62,500 and 83,333 plants ha-1). The assay was carried out at the Papaloapan University Campus Loma Bonita, Oaxaca. Genotypes used were: DK-357, HE-1A17, H-520, NH5, H-564C and the synthetic variety VS-536. Experimental design consisted of a randomized blocks. Each experimental plot was 12.8 m2. Variables studied were: plant height (cm), days to male flowering, days to silking, ear weight (g), ear length (cm), number of grains per ear, weight of a hundred grains (g), grain yield (kg ha-1), and dry leaf yield (kg ha-1). An analysis of variance was performed for genotypes, densities, and genotypes by densities interaction. In addition, a Tukey test for pairwise comparison was run (P ≤ 0.05). There were significant differences among genotypes, densities and genotype by density interactions. The hybrid H-520 produced the highest grain yield (5,993.3 kg ha-1). The synthetic variety VS-536 showed higher leaf yield than anyone else.

Rural households in agricultural economies are vulnerable to several environmental risks such as fires, floods, and droughts that may affect their productivity in whole or in part. These hazards are especially relevant in developing countries where farmers have few or no access to traditional risk-transfer techniques, such as insurance and finance, and where low governmental investments in rural infrastructure, risk assessment techniques, or early warning systems makes the aftermath of such hazards more expensive and results in slower recovery for those who are affected. In this paper, we use historical satellite data (Terra) of burned areas in South America to fit a semiparametric spatial model, based on kernel smoothing and on a nonlinear relationship between average time between events and damage, to assess the environmental hazard affecting the land’s productivity. The results were twofold: first, we were able to develop a spatial assessment of fire hazard, and second, we were able to evaluate how much a farmer may lose in terms of productivity per hectare due to the environmental hazard. The methodology may be easily adapted to other world regions; to different environmental hazards such as floods, windbreak, windthrow, or related land-use changes; or to integrate various environmental hazards simultaneously, as long as they can be monitored via remote sensing (e.g., satellite imagery, aerial photographs, etc).

In this study, survival of spruce (Picea abies [L.] Karst.) trees in mixed- and mono-species stands was analyzed using the database of Rhineland-Palatinate’s forest damage survey (FDS). The influence of species mixture on tree survival probability was analyzed using data from 9864 trees, of which 2866 spruce trees have been analysed in detail. Data was collected on 495 research plots in a series of continuous measurements taken since 1984. For estimating survival probability, the Kaplan–Meier method was applied to achieve a first overview about possible effects. The analysis was then extended using Accelerated Failure Time (AFT) models to estimate the parameters of a Weibull function, used to describe survival times. The resulting models were used to simultaneously analyze the effects of intensity of mixture (represented by Shannon–Weaver-Index and, alternatively, by species proportion), time since harvest and site characteristics. Results obtained indicate positive effects of species mixture on resistance of spruce trees: survival probabilities increase with increasing intensity of mixture, regardless whether mixture is characterised by Shannon–Weaver-Index or species proportion. Spruce trees in monocultures on average site conditions will reach age 100 with a probability of 80%. Spruce trees growing in a moderately mixed stand (average Shannon–Weaver-Index 0.4) show a slight increase in survival probability to a 83% probability of reaching age 100 whilst spruce trees in a more diverse stand (average Shannon–Weaver-Index 1.2) have a 97% probability of reaching age 100. An admixture of 50% thus leads to an increase in survival probability of 17 percentage points. Site variables even show a stronger impact on survival than tree species mixture. From these variables wet soils had the strongest negative influence on spruce survival, while orographic conditions of saddles, anticlines, valleys, trenches or dells showed the strongest positive influence on survival. However, the strongest influence on spruce survival was recent harvest activity. The more time had passed since the harvest operation, the less likely residual trees were to succumb to stresses.

The two major pathways for the metabolism of estradiol-17β (E 2 ) are the 2- and 16-hydroxylase pathways. Research has suggested that the increased production of the estrogenically active 16-hydroxy products such as estriol (E 3 ) may be involved in increased susceptibility to breast cancer. 4-Nonylphenol (4-NP) is an environmental estrogen that also can activate the pregnane-X receptor (PXR) and induce P-450 enzymes responsible for the production of E 3 . It is hypothesized that 4-NP may act in part as an environmental estrogen by increasing E 3 production. Based on its affinity for the estrogen receptor (ER) alone, 4-NP may be more potent than predicted at increasing mammary cancer incidence in the MMTVneu mouse. Female mice were treated per os for 7 days at 0, 25, 50 or 75 mg kg -1 day -1 4-NP to investigate the effects of 4-NP on hepatic estrogen metabolism after an acute treatment. 4-Nonylphenol increased the hepatic formation of E 3 in a dose-dependent manner. However, serum E 3 concentrations were only increased at 25 mg kg -1 day -1 presumably due to direct inhibition of E 3 formation by 4-NP. MMTVneu mice were then treated for 32 weeks at 0, 30 or 45 mg kg -1 day -1 4-NP to determine its effects on mammary cancer formation and estrogen metabolism. 4-Nonylphenol increased mammary cancer formation in the MMTVneu mice at 45 mg kg -1 day -1 but not at 30 mg kg -1 day -1 . Mice treated with an equipotent dose of E 2 , 10 μg kg -1 day -1 , based on the relative binding affinities of nonylphenol and estradiol for ERα, did not develop mammary cancer. This suggests that nonylphenol is more potent than predicted based on its affinity for the estrogen receptor. However, no changes in serum E 3 , concentrations or hepatic E 3 production were measured after the chronic treatment. Changes in E 3 formation were correlated with increased CYP2B levels after the 7 day 4-NP treatment, and repression of CYP2B and CYP3A after 32 weeks of 4-NP treatment. Microarray analysis and Q-PCR of liver mRNA from the mice treated for 32 weeks demonstrated a decrease in RXRα, the heterodimeric partner of the PXR, which may in part explain the repressed transcription of the P450s measured. In conclusion, 4-NP treatment for 32 weeks increased mammary cancer formation at a dose of 45 mg kg -1 day -1 . However, chronic treatment with 4-NP did not increase hepatic E 3 formation or serum E 3 concentrations. The transient induction by 4-NP of hepatic E 3 formation and serum concentrations is most likely not involved in the increased incidence of mammary cancer in MMTVneu mice since E 3 serum concentrations were only increased at 25 mg kg -1 day -1 , a dose that was not sufficient to induce mammary tumor formation. Nevertheless, the induced hepatic E 3 production in the acute exposures to 4-NP was indicative of an increase in mammary cancer incidence after the chronic exposure.

Some ultrastructural changes can be observed in diseased Saccharum officinarum L. (cv. Cuba 120-78) plants with visual symptoms of yellow leaf syndrome (YLS), used to discriminate between healthy and diseased plants. Abaxial epidermis of diseased leaves shows a large amount of adhered superficial bodies, which partially occluded some stomata. Bundle sheath cells surrounding the bottom of phloem of diseased leaves are separated from the conducting tissues by a large layer of an amorphous matrix similar to wax. Debris of the end wall can be observed in large xylem vessels. Sometimes, spherical bodies similar to phytoplasma can be observed in the intercellular spaces of bundle sheath cells. These particles have never been observed in healthy plants. YLS was also associated to an increase of the concentration of reducing sugars, glucose index, and glycoproteins recovered in juices whereas the amount of sucrose decreases. Sugarcane juices obtained from both healthy and YLS-affected Cuba 120-78 cultivars of sugarcane contained putrescine (PUT), cadaverine (CAD), spermidine and spermine (SPM) as free and macromolecules-conjugated compounds. Only CAD and SPM appeared as acid-soluble conjugates to small molecules whereas PUT and CAD are the major polyamines (PAs) conjugated to macromolecules, mainly to high molecular mass glycoproteins. The disease was associated to an increase in total PA fraction. Arginase and ornithine decarboxylase activities, responsible for the synthesis of PUT, were higher in YLS juices than in those obtained from healthy plants. CAD and SPM presumably conjugated mostly to chlorogenic, syringic and ferulic acids in juices from YLS plants.

Leaf scald is a vascular disease of sugarcane caused by Xanthomonas albilineans. Scalded leaves show white-yellowish streaks alternating with green zones in parallel to the main veins. These zones develop large bulliform cells, probably as a consequence of the wilting process. Moreover, a gum exudate occludes phloem and bundle vessels, and partially enters mesophyll cells. Some lysigenic cavities appear near the xylem. However, the white-yellowish streaks show both phloem and xylem completely occluded by the gum and the overall mesophyll appears to be full of this bacterial secretion, as revealed by scanning electron microscopy. The gum in conducting tissues has been purified from juice obtained from scalded stalks by precipitation with isopropyl alcohol and size-exclusion chromatography. It was identified as a xanthan-like polysaccharide and found to be composed of glucose, mannose and glucuronic acid by acidic hydrolysis and capillary electrophoresis.

En este trabajo se predice la estimacion de estados como la biomasa y la concentracion de productos de una bacteria sulfato reductora empleando unicamente mediciones de la concentracion de sulfato (sustrato) bajo la hipotesis de una cinetica de consumo de sulfato desconocida. El proceso fue considerado como un cultivo continuo, donde el modelo cinetico correspondiente para las concentraciones de biomasa, sulfato y sulfuro fue corroborado con datos experimentales. El diseno de la metodologia de estimacion propuesta considera una ganancia adaptable. Los resultados de estimacion fueron generados por medio de simulaciones numericas y muestran un comportamiento satisfactorio.

The goal of this work is to describe the design of a feedback controller to regulate the Hexavalent chromium (Cr (VI)) concentration in industrial plating wastewater in a tubular reactor. Cr(VI) is a major pollutant present in industrial wastewaters common to the metal and mineral processing as well as to plating industries. For control purposes, a dynamic model of a plug flow reactor with dispersion is developed in the form of partial differential equations (PDE) via applying classical conservation principles; this model is experimentally corroborated using laboratory data. The proposed controller is based on uncertainty observer to infer unknown terms as diffusive transport and Cr(VI) kinetic rate; also Generic Model Controller (GMC) is coupled with this estimation methodology to provide robustness against model uncertainties. The controller leads to nonlinear PID plus double integral action, where the tuning rules are given in terms of the observer and GMC gains. A theoretical frame is given in order to show the stability properties of the closed-loop system under the proposed controller. Numerical simulation illustrates performance of the methodology proposed; a comparison with observer based I/O linearizing controller and a well tuned PID controller is done, which allows concluding that the observer based Generic Model Controller exhibits better performance.

Proteínas relacionadas con la defensa en la interacción sporisorium scitamineum - caña de azúcar. el presente trabajo se realizó en el centro nacional de sanidad agropecuaria (censa), habana, cuba, durante el periodo 2001-2005, con el objetivo de determinar los patrones isoenzimáticos superóxido dismutasa y las secuencias de proteínas relacionadas con la defensa inducida en la interacción s. scitamineum - caña de azúcar, para lo cual fueron inoculadas con el patógeno las yemas de las variedades ja60-5 (susceptible) y m31/45 (resistente) con una suspensión de esporidios del patógeno. la separación electroforética en condiciones nativas permitió la detección de dos isoformas ácidas de la enzima, una que se induce en mayor magnitud en la variedad resistente en comparación con la susceptible y otra que mantiene su nivel constitutivo para ambas variedades. el análisis adnc-aflp permitió la obtención de secuencias de prs homólogas a glucanasas (pr2), quitinasas (pr3) y osmotina (pr5) inducidas diferencialmente en la variedad resistente. los resultados obtenidos sugieren la participación de la enzima superóxido dismutasa en la señalización de la infección en esta interacción; así como la participación de prs en la respuesta de resistencia inducida. todo esto brinda la posibilidad de utilizar dichas proteínas como posibles marcadores bioquímicos y moleculares en programas de selección de variedades resistentes al carbón de la caña de azúcar.

Territorial Planning acquires the complex category due to the relational dynamics that different implicated actors print into the style and the narrative associated. The way of systematizing the complexity of opinions and styles, on the selection of decisions, are not supported on the computational tools themselves, but on the epistemological base that underlies to the culture of organization or organizations implicated in territorial planning .This work aims to integrate, from an organization’s cognitive base, a series of computational tools that until now are used in an individual way. Integration is based on methodology named Cognitive Strategies.

The structural changes that take place in sugar cane buds during the infection with Ustilago scitaminea were studied. Buds of the cultivars SP79-2312 and NA56-79, resistant and susceptible to this fungus, were inoculated with teliospores of U. scitaminea. They were placed in trays and maintained in darkness at 31 degrees and 80% relative humidity. Thirty buds of each cultivar left without inoculating as controls. The samplings were carried out at 16, 40 and 72 h after inoculation, taking 10 inoculated buds of each cultivar and same number of healthy buds. The tissues were fixed in glutaraldehyde and osmium tetroxide, later they were dehydrated in acetone and embedded in Spurr resin. Semi-fine and ultra-fine transverse sections were prepared, and were observed in light and electron microscopes respectively. It was proven that in spite of having broken the barrier of resistance of SP79-2312, for the inoculation method used, always the development of the fungus in this resistant cultivar was slower than in the susceptible one NA56-79. At 14 h post-inoculation, the fungus was not observed in the resistant cultivar, and it was scarce in the susceptible one. At 40 h an increament in the quantity of hyphaes was noticed and even more at 72 h. The damages in the cellular structure were more drastic from the second sampling, being increased in the last one. The detected alterations were: formation of electrodense granules inside the cells, increament of vacuoles, vesicles and endoplasmic reticulum cisternae, as well as rupture of membranes inside of the cells.

To characterise the coiled bodies in meristematic nuclei of Saccharum officinarum, immunofluorescence labelling with antibodies against components of the splicing (U2B′′ and Sm core protein B) and pre-rRNA processing (fibrillarin) complexes was used in cells from the dormant root primordia and from roots at different times after activation to the steady state of proliferation. The number, size and distribution of coiled bodies varied in the meristematic tissue depending on cell activity. While G0 cells in the dry primordia and proliferating cells showed a similar number of coiled bodies attached to their nucleoli, the number of nucleoplasmic coiled bodies greatly increased after the primordia were stimulated to proliferate. Their number remained steady from the time the meristematic population reached the steady state of proliferation, as estimated by flow cytometry. Fractionation studies demonstrated that coiled bodies are a part of the underlying nuclear matrix. Comparison of immunocytochemical and cytochemical data from confocal and electron microscopical studies demonstrated that the nucleolar and nucleoplasmic coiled bodies detected by confocal microscopy shared many features, suggesting that they form a family of closely related structures., This work has been supported by the Spanish DGES (projects PB96-0909 and PB98-0647) and by the CSIC/CITMA agreement (project 99CU0010). R