Predictability of biomass burning in response to climate changes

Climate is an important control on biomass burning, but the sensitivity of fire to changes in temperature and moisture balance has not been quantified. We analyze sedimentary charcoal records to show that the changes in fire regime over the past 21,000 yrs are predictable from changes in regional climates. Analyses of paleo- fire data show that fire increases monotonically with changes in temperature and peaks at intermediate moisture levels, and that temperature is quantitatively the most important driver of changes in biomass burning over the past 21,000 yrs. Given that a similar relationship between climate drivers and fire emerges from analyses of the interannual variability in biomass burning shown by remote-sensing observations of month-by-month burnt area between 1996 and 2008, our results signal a serious cause for concern in the face of continuing global warming.

La reforma tributaria uruguaya de 2006: algunas consideraciones de economía política y comportamental

Incluye bibliografia

Servicios públicos y reforma fiscal ambiental en América Latina

En este documento se examina la pertinencia y oportunidad de las Reformas Fiscales Ambientales (RFA) para tres servicios públicos en cinco países de la región (Chile, Ecuador, El Salvador, México y Uruguay). Se discute el significado de la RFA en la oferta y uso de esos servicios y se muestra que existen prioridades comunes y específicas de cada país, dependiendo de cómo son producidos, “comercializados” y utilizados, lo que a su vez se relaciona con las estructuras sociales y productivas, las políticas públicas, y la conformación y dinámica de los mercados relevantes. Luego de caracterizar las estructuras de mercado, políticas de precios y tarifas, y acceso o uso de los servicios por estratos de hogares y sectores productivos, se identifican políticas fiscales ambientales que cabría considerar, tomando como referencia las experiencias exitosas de países más avanzados. Se identifican los posibles efectos no deseados por su regresividad o deterioro de la competitividad de agentes productores y se discuten medidas compensatorias o complementarias de las innovaciones ambientales.

Formación y determinación de precios en el Uruguay

Tener mejor información acerca de los mecanismos de formación y determinación de precios es de gran importancia para el diseño de las políticas de combate a la inflación. Combinando análisis de evolución de precios (altas y bajas mensuales) con consideraciones institucionales es posible clasificar a los precios que componen el IPC de acuerdo a su estructura de mercado. El estudio pone de manifiesto la existencia de bienes y establecimientos con potencial para fijar sus precios por encima del que fijaría un mercado competitivo. Esa situación podría tener un peso de hasta un tercio del índice de precios al consumo. Se destaca el caso del rubros restaurante y hoteles y en servicios “personalizados” y/o por contratos de adhesión.

Evolução do ciclo vital de Poecilia vivipara (Cyprinodontiformes: Poeciliidae) em um gradiente de predação

O presente estudo teve como objetivo testar previsões da teoria sobre a influência da predação na evolução dos ciclos vitais. Como modelo de estudo, foram estudadas populações do peixe Poecilia vivipara que habitam o Parque Nacional da Restinga de Jurubatiba, no sistema lagunar Norte-Fluminense, estado do Rio de Janeiro. Neste sistema lagunar, P. vivipara está sujeita à predação por peixes piscívoros (e.g. a traíra Hoplias malabaricus) em parte das lagoas, mas está livre destes predadores em outras lagoas. Foram estudadas três lagoas em que P. vivipara coexiste com seus predadores piscívoros e três em que estes estão ausentes. A ictiofauna das seis lagoas foi amostrada através de redes de arrasto e espinhel. Em laboratório, as fêmeas e os machos de P. vivipara foram dissecados para remoção de suas gônadas. As gônadas das fêmeas foram categorizadas em seis diferentes estágios de desenvolvimento. A partir do terceiro estágio, os embriões foram contados e medidos (maior diâmetro). Os exemplares de P. vivipara e suas gônadas foram secos em estufa a 60ºC e pesados em balança analítica (0,01 mg). Os aspectos do ciclo vital analisados foram: (1) investimento reprodutivo das fêmeas (massa gonadal/massa total da fêmea); (2) índice gonadossomático dos machos (massa gonadal/massa total do macho); (3) fecundidade (número de embriões); (4) comprimento médio dos embriões; e (5) massa seca média dos embriões (massa gonadal/fecundidade). O efeito da predação foi testado com uma ANCOVA aninhada, com regime de predação (alta intensidade, baixa intensidade), população de origem (aninhada dentro do regime de predação) e coleta como variáveis independentes, e massa somática e estágio embrionário como covariáveis. De acordo com o previsto pela teoria, as fêmeas dos ambientes de baixa predação apresentaram embriões maiores, mas, contrariando as previsões teóricas, também apresentaram maior fecundidade e...

Leukotriene B4-loaded microspheres: a new therapeutic strategy to modulate cell activation

Abstract Background Leukotriene B4 (LTB4) is a potent inflammatory mediator that also stimulates the immune response. In addition, it promotes polymorphonuclear leukocyte phagocytosis, chemotaxis, chemokinesis and modulates cytokines release. Regarding chemical instability of the leukotriene molecule, in the present study we assessed the immunomodulatory activities conferred by LTB4 released from microspheres (MS). A previous oil-in-water emulsion solvent extraction-evaporation method was chosen to prepare LTB4-loaded MS. Results In the mice cremasteric microcirculation, intraescrotal injection of 0.1 ml of LTB4-loaded MS provoked significant increases in leukocyte rolling flux, adhesion and emigration besides significant decreases in the leukocyte rolling velocity. LTB4-loaded MS also increase peroxisome proliferator-activated receptor-α (PPARα) expression by murine peritoneal macrophages and stimulate them to generate nitrite levels. Monocyte chemoattractant protein-1 (MCP-1) and nitric oxide (NO) productions were also increased when human umbilical vein and artery endothelial cells (HUVECs and HUAECs, respectively) were stimulated with LTB4-loaded MS. Conclusion LTB4-loaded MS preserve the biological activity of the encapsulated mediator indicating their use as a new strategy to modulate cell activation, especially in the innate immune response.

Predictability of biomass burning in response to climate changes

Climate is an important control on biomass burning, but the sensitivity of fire to changes in temperature and moisture balance has not been quantified. We analyze sedimentary charcoal records to show that the changes in fire regime over the past 21,000 yrs are predictable from changes in regional climates. Analyses of paleo- fire data show that fire increases monotonically with changes in temperature and peaks at intermediate moisture levels, and that temperature is quantitatively the most important driver of changes in biomass burning over the past 21,000 yrs. Given that a similar relationship between climate drivers and fire emerges from analyses of the interannual variability in biomass burning shown by remote-sensing observations of month-by-month burnt area between 1996 and 2008, our results signal a serious cause for concern in the face of continuing global warming.

7000-year human legacy of elevation-dependent European fire regimes

Variability in fire regime at the continental scale has primarily been attributed to climate change, often overshadowing the widely potential impact of human activities. However, human ignition modifies the rhythm of fire episodes occurrence (fire frequency), whereas land use alters vegetation composition and fuel load, and thus the amount of biomass burned. It is unclear, however, whether and how humans have exercised a significant influence over fire regimes at continental and millennial scales. Based on sedimentary charcoal records, we use new alternative estimate of fire frequency and biomass burned for the last 16000 years (here after 16 ky) that we evaluate with outputs from climate, vegetation, land use and population models. We find that pronounced regional-scale land use changes in southern Europe at the beginning of the Neolithic (8–6 ky), during the Bronze Age (5–4 ky) and the medieval period (1 ky) caused a doubling of fire frequency compared to the Holocene average (the last 11.5 ky). Despite anthropogenic influences, southern European biomass burned decreased from 7 ky, which is in line both with changes in orbital parameters leading climate cooling and also reductions in biomass availability because of land use. Our study underscores the role of elevation-dependent parameters, and particularly biomass and land management, as major drivers of fire regime variability. Results attest a determinant anthropogenic driving-force on fire regime and a decrease in fire-carbon emissions since 7 ky in Southern Europe.

Charcoal records of two sediment cores off SW Africa

We analyze sedimentary charcoal records to show that the changes in fire regime over the past 21,000 yrs are predictable from changes in regional climates. Analyses of paleo- fire data show that fire increases monotonically with changes in temperature and peaks at intermediate moisture levels, and that temperature is quantitatively the most important driver of changes in biomass burning over the past 21,000 yrs. Given that a similar relationship between climate drivers and fire emerges from analyses of the interannual variability in biomass burning shown by remote-sensing observations of month-by-month burnt area between 1996 and 2008, our results signal a serious cause for concern in the face of continuing global warming.