Poverty dynamics, ecological endowments, and land use among smallholders in the Brazilian Amazon.

Rural settlement in previously sparsely occupied areas of the Brazilian Amazon has been associated with high levels of forest loss and unclear long-term social outcomes. We focus here on the micro-level processes in one settlement area to answer the question of how settler and farm endowments affect household poverty. We analyze the extent to which poverty is sensitive to changes in natural capital, land use strategies, and biophysical characteristics of properties (particularly soil quality). Cumulative time spent in poverty is simulated using Markovian processes, which show that accessibility to markets and land use system are especially important for decreasing poverty among households in our sample. Wealtheir households are selected into commercial production of perennials before our initial observation, and are therefore in poverty a lower proportion of the time. Land in pasture, in contrast, has an independent effect on reducing the proportion of time spent in poverty. Taken together, these results show that investments in roads and the institutional structures needed to make commercial agriculture or ranching viable in existing and new settlement areas can improve human well-being in frontiers.

Rebuilding Babel: finding common development solutions using cross-contextual comparisons of multidimensional well-being / Reconstruindo Babel: comparando o bem-estar multidimensional de diferentes contextos culturais em busca de soluções comuns para o desenvolvimento / Reconstruyendo Babel: la comparación del bienestar multidimensional de diferentes contextos culturales en búsqueda de soluciones comunes para el desarrollo

In this paper the theoretical tradition of coping strategies and capital portfolios is used as the basis for adaption and combination of existing methodologies to analyze well-being in rural households. Special attention is given to comparisons among different contexts. First we estimate a multidimensional measurement of poverty based on fuzzy logic for two areas of rural frontiers: Nang Rong, Thailand, and Altamira, in the Amazon Basin in Brazil. To enable a cross-contextual comparison we calculated a second estimate using a subset of shared measurements in the two areas. The findings suggest that the pattern of responses on a range of numerous key variables - including education, income and demographic dependency ratio - is robust for the model specification. It is concluded that comparative generalizations, useful in formulating cost-effective public policy interventions across contexts, could be satisfactorily identified in many situations. More generically, this approach provides researchers and policymakers with a framework for understanding the interaction of contexts with the subjective construction of well-being. The understanding of this interaction is useful for distinguishing stable corollaries of poverty from those that are volatile across contexts.

Com base na tradição teórica relativa a estratégias de sobrevivência e portfólios de capitais, propõe-se uma adaptação e combinação de metodologias existentes para análise do bem-estar em domicílios rurais, com especial atenção à comparação entre diferentes contextos. Em primeiro lugar, estimou-se uma medida multidimensional de pobreza, baseada em lógica nebulosa, para duas áreas de fronteira agrícola: Nang Rong, na Tailândia, e Altamira, no Brasil. Para que a comparação entre os contextos fosse possível, uma segunda estimativa foi obtida, utilizando-se um subconjunto das medidas presentes nas duas áreas de estudo. Os resultados sugerem que o padrão de resposta em relação a várias características-chave - por exemplo, educação, renda e razão de dependência demográfica - é robusto à especificação do modelo. Conclui-se que generalizações comparativas, úteis na formulação de políticas públicas que sejam custo-eficientes quanto à intervenção em contextos distintos, poderiam ser identificadas em diversas situações. Mais genericamente, a presente abordagem fornece aos pesquisadores e gestores de políticas um arcabouço que possibilite entender a interação do contexto com a construção subjetiva de bem-estar. A compreensão dessa interação é útil para distinguir corolários estáveis de pobreza daqueles que são voláteis em contextos distintos.

En base a la tradición teórica relativa a estrategias de supervivencia y carteras de capitales, se propone una adaptación y combinación de metodologías existentes para analizar el bienestar en viviendas rurales, con especial atención a la comparación entre diferentes contextos. En primer lugar, se estimó una medida multidimensional de pobreza, basada en lógica nebulosa, para dos áreas de frontera agrícola: Nang Rong, en Tailandia, y Altamira, en Brasil. Para que la comparación entre los contextos fuese posible, se llegó a una segunda estimación, utilizando un subconjunto de las medidas presentes en las dos áreas de estudio. Los resultados sugieren que el patrón de respuesta en relación a varias características clave - por ejemplo, educación, ingresos y razón de dependencia demográfica - es robusto en lo que concierne a la especificación del modelo. Se concluye que generalizaciones comparativas, útiles en la formulación de políticas públicas costo-eficientes en lo que se refiere a la intervención en contextos distintos, podrían identificarse en diversas situaciones. Más genéricamente, el presente abordaje ofrece a investigadores y gestores de políticas una base que posibilite entender la interacción del contexto con la construcción subjetiva de bienestar. La comprensión de esta interacción es útil para distinguir corolarios estables de pobreza de aquellos que son volátiles en contextos distintos.

Interactions of the streptococcal C5a peptidase with human fibronectin.

Group B Streptococci (GBS) is a leading cause of sepsis and meningitis in neonates and immunocompromised adults in western countries. GBS do not bind to fibronectin (Fn) in solution, but will bind to Fn adsorbed onto a solid surface. The reason for the specificity of this binding is unknown. Single molecule force spectroscopy was used to test the hypothesis that GBS, through streptococcal C5a peptidase (ScpB) molecules present on the surface of the bacteria, binds to a motif created by the juxtaposition of multiple adjacent Fn molecules. Atomic force microscopy (AFM) topographical images of adsorbed Fn deposited from various Fn coating concentrations were used to determine the Fn surface concentration. ScpB was tethered to an AFM tip with all surface modifications characterized by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. At the lowest Fn coverages the probability of observing a ScpB-Fn binding event increased linearly with Fn surface coverage. As an Fn monolayer was reached the probability of a ScpB-Fn binding event occurring increased markedly ( approximately 50 fold), with a concomitant increase in the rupture force from 17 pN to 33 pN. These results are consistent with the hypothesis that ScpB binds to a motif created by the juxtaposition of multiple Fn molecules.

Structure and reactivity of adsorbed fibronectin films on mica.

Understanding the interactions of adsorbed fibronectin (Fn) with other biomolecules is important for many biomedical applications. Fn is found in almost all body fluids, in the extracellular matrix, and plays a fundamental role in many biological processes. This study found that the structure (conformation, orientation) and reactivity of Fn adsorbed onto mica is dependent on the Fn surface concentration. Atomic force microscopy and x-ray photoelectron spectroscopy were used to determine the surface coverage of adsorbed Fn from isolated molecules at low surface coverage to full monolayers at high surface coverage. Both methods showed that the thickness of Fn film continued to increase after the mica surface was completely covered, consistent with Fn adsorbed in a more upright conformation at the highest surface-Fn concentrations. Time-of-flight secondary ion mass spectrometry showed that relative intensities of both sulfur-containing (cystine, methionine) and hydrophobic (glycine, leucine/isoleucine) amino acids varied with changing Fn surface coverage, indicating that the conformation of adsorbed Fn depended on surface coverage. Single-molecule force spectroscopy with collagen-related peptides immobilized onto the atomic force microscope tip showed that the specific interaction force between the peptide and Fn increases with increasing Fn surface coverage.

Atomic force microscopy and surface plasmon resonance investigation of fibronectin interactions with group B streptococci.

The interactions of fibronectin (Fn) with group B streptococci (GBS) were investigated using the atomic force microscope (AFM) and surface plasmon resonance (SPR) biosensing. Submonolayer amounts of Fn were immobilized onto the AFM tip by two different methods, using either a sulfosuccinimidyl-4-(N-maleimidomethyl) cycholhexane-1-carboxylate (SMCC) linker or a pyridyldithio poly(ethylene glycol) succinimidylpropionate (NHS-PEG-PDP) linker. Each step of both immobilization methods was characterized using x-ray photoelectron spectroscopy. Time-of-flight secondary ion mass spectrometry experiments indicated both methods produced Fn immobilized in a similar conformation. AFM force-distance curves from live GBS plated onto polystyrene exhibited several types of interactions between the Fn functionalized AFM tip and the surface of capsule-deficient GBS (no interactions, interactions with the cell wall, Fn unfolding, large specific unbinding events, and small specific unbinding events). From analysis of the force-distance curves that exhibited only a single specific unbinding event, the work of adhesion and rupture force for the SMCC immobilized Fn tips (11,131 pN nm and 213 pN) were larger than the corresponding values for the NHS-PEG-PDP immobilized Fn tips (8115 pN nm and 189 pN). The unbinding event occurred at distances approximately 100 nm further from the surface with the NHS-PEG-PDP immobilized Fn tip compared to SMCC immobilized Fn tip. The SPR experiments of soluble Fn with adsorbed serine protease C5a peptidase (Scp), the surface protein on GBS that binds Fn, showed that both low (millimolar) and high binding (nanomolar) affinity interactions were present. However, the low binding affinity interactions dominated the adsorption process and, with increasing Fn solution concentration, the amount of Scp bound to Fn via the high binding affinity interaction decreased. These data confirm that Scp binds only to adsorbed Fn at the Fn concentrations typically present in blood plasma.

High-affinity interaction between fibronectin and the group B streptococcal C5a peptidase is unaffected by a naturally occurring four-amino-acid deletion that eliminates peptidase activity.

The streptococcal C5a peptidase (ScpB) of group B streptococci (GBS) is found in virtually all clinical GBS isolates and is required for mucosal colonization in a neonatal mouse model. ScpB inhibits neutrophil chemotaxis by enzymatically cleaving the complement component C5a. We previously identified a second function of ScpB as a fibronectin (Fn) adhesin using phage display. However, phage display can identify low-affinity interactions. We therefore measured the affinity of both full-length recombinant ScpB (FL-ScpB) and the 110-amino-acid phage display fragment (Scp-PDF) for immobilized Fn using surface plasmon resonance. The affinity for Fn was very high for both FL-ScpB (equilibrium dissociation constant [KD] = 4.0 nM) and Scp-PDF (KD = 4.4 nM) and is consistent with a biologically significant role for the adhesin activity of ScpB. We also studied the Fn adhesin activity of a common natural variant of ScpB (ScpBDelta) that contains a 4-amino-acid deletion that eliminates peptidase activity. The integrity of scpB is otherwise maintained, suggesting that the Fn adhesin activity of ScpB may be responsible for its conservation in these strains. The affinities of both FL-ScpBDelta (KD = 2.4 nM) and ScpBDelta-PDF (KD = 1.4 nM) for Fn are unaffected by the deletion. Complementation in trans by both scpB and scpBDelta corrected the Fn-binding defect of an scpB deletion mutant GBS strain to an identical degree. The high affinity of ScpB for Fn and the maintenance of this affinity in ScpBDelta support our hypothesis that the Fn adhesin activity of scpB plays a role in virulence.

Surface chemical and mechanical properties of plasma-polymerized N-isopropylacrylamide.

Surface-immobilized poly(N-isopropyl acrylamide) (pNIPAM) is currently used for a wide variety of biosensor and biomaterial applications. A thorough characterization of the surface properties of pNIPAM thin films will benefit those applications. In this work, we present analysis of a plasma-polymerized NIPAM (ppNIPAM) coating by multiple surface analytical techniques, including time-of-flight secondary-ion mass spectrometry (ToF-SIMS), contact angle measurement, atomic force microscopy (AFM), and sum frequency generation (SFG) vibrational spectroscopy. ToF-SIMS data show that the plasma-deposited NIPAM polymer on the substrate is cross-linked with a good retention of the monomer integrity. Contact angle results confirm the thermoresponsive nature of the film as observed by a change of surface wettability as a function of temperature. Topographic and force-distance curve measurements by AFM further demonstrate that the grafted film shrinks or swells depending on the temperature of the aqueous environment. A clear transition of the elastic modulus is observed at 31-32 degrees C. The change of the surface wettability and mechanical properties vs temperature are attributed to different conformations taken by the polymer, which is reflected on the outmost surface as distinct side chain groups orienting outward at different temperatures as measured by SFG. The results suggest that a ppNIPAM thin film on a substrate experiences similar mechanical and chemical changes to pNIPAM bulk polymers in solution. The SFG result provides evidence supporting the current theory of the lower critical solution temperature (LCST) behavior of pNIPAM.