Extensiones autoadjuntas hamiltonianas en un intervalo de la recta real: El operador energía cinética.

Based on physical arguments, we find the position, momentum, and kinetic energy operators in the interval (0, ℓ) of the real line. We characterize the domain of the canonical commutation rule (between position and momentum operators) and the validity of the uncertainty principle.Haciendo uso de argumentos fı´sicos, hallamos los operadores momentum y energı´a cin´etica en el intervalo (0, ℓ) de la recta real, ası´ como el operador posici´on. Caracterizamos el dominio de la regla can´onica de conmutaci´on (entre los operadores posici´on y momentum) y de validez del principio de incertidumbre

Conservation strategies to mitigate impacts from climate change in Amazonia

Protected area systems and conservation corridors can help mitigate the impacts of climate change on Amazonian biodiversity. We propose conservation design criteria that will help species survive in situ or adjust range distributions in response to increased drought. The first priority is to protect the western Amazon, identified as the ‘Core Amazon’, due to stable rainfall regimes and macro-ecological phenomena that have led to the evolution of high levels of biodiversity. Ecotones can buffer the impact from climate change because populations are genetically adapted to climate extremes, particularly seasonality, because high levels of habitat diversity are associated with edaphic variability. Future climatic tension zones should be surveyed for geomorphological features that capture rain or conserve soil moisture to identify potential refugia for humid forest species. Conservation corridors should span environmental gradients to ensure that species can shift range distributions. Riparian corridors provide protection to both terrestrial and aquatic ecosystems. Multiple potential altitudinal corridors exist in the Andes, but natural and anthropogenic bottlenecks will constrain the ability of species to shift their ranges and adapt to climate change. Planned infrastructure investments are a serious threat to the potential to consolidate corridors over the short and medium term

The Added Complications of Climate Change: Understanding and Managing Biodiversity, Ecosystems, and Ecosystem Services Under Multiple Stressors.

Ecosystems around the world are already threatened by land-use and land-cover change, extraction of natural resources, biological disturbances, and pollution. These environmental stressors have been the primary source of ecosystem degradation to date, and climate change is now exacerbating some of their effects. Ecosystems already under stress are likely to have more rapid and acute reactions to climate change; it is therefore useful to understand how multiple stresses will interact, especially as the magnitude of climate change increases. Understanding these interactions could be critically important in the design of climate adaptation strategies, especially because actions taken by other sectors (eg energy, agriculture, transportation) to address climate change may create new ecosystem stresses

Utilización de inóculos comerciales conteniendo bacterias productoras de ácido láctico sobre las características fermentativas y estabilidad aeróbica de ensilaje de maíz

This study evaluated two treatments based on addition of two commercial microbial inoculants of lactic acid-producing bacteria (LAPB), one of the homolactic type (HOT) and the other a combination of homolatic with heterolactic bacteria (HHT), plus a control treatment without inoculation (CNT), on the fermentative characteristics of tropical maize in micro-silos and aerobic stability (AS) of the resulting silage. The fermentative characteristics were determined in triplicate samples taken at various lengths of fermentation (15, 30, 58 and 90 d), which were analyzed for pH, concentration of organic acids and NHL. To evaluate AS, changes in pH and temperature of the silage were monitored during five days of exposure to air. No significant differences were found among treatments in any of the fermentation characteristics studied. HOT resulted in the numerically lowest average pH (4.23) and the highest average percentage content of lactic acid (2.18), followed by HHT (4.28 and 2.11) and CNT (4.32 and 1.94), respectively. Also, regarding indicators of AS there were no significant differences among treatments, but numerically the average pH of exposed HOT silage was lower (5.30 vs 5.43 the average value of both HHT and CNT) and there was a trend (P <0.15) toward lower average temperature (°C ) in favor of HHT (29.61 vs. 30.26 and 30.28 for HOT and CNT silages). In general, the use of LAPB inoculants in tropical maize silage did not result in large differences relative to non-inoculated silage in the variables under study regarding fermentation characteristics and AS.Se evaluaron dos tratamientos basados en la adición de dos inóculos microbianos comerciales, uno a base de bacterias productoras de ácido láctico (BPAL) homofermentativas (THO) y el otro una combinación de estas con heterofermentativas (THH), además de un tratamiento control sin inoculación (TCN), en sus efectos sobre las características fermentativas de maíz tropical en micro-silos y la estabilidad aeróbica (EA) del ensilaje resultante. Las características fermentativas se determinaron en muestras por triplicado, tomadas a diferentes largos de fermentación (15, 30, 58, y 90 d), que se analizaron para pH, concentración de ácidos orgánicos y NHL. Para evaluar la EA se monitoreó los cambios de pH y temperatura del ensilaje expuesto al aire durante cinco días. No se encontró diferencias significativas entre tratamientos en ninguna de las características fermentativas incluidas. Numéricamente el THO mostró en promedio el menor pH (4.23) y el mayor contenido porcentual de ácido láctico (AL) (2.18), seguido respectivamente por THH (4.28 y 2.11) y TCN (4.32 y 1.94). Los indicadores de EA tampoco difirieron significativamente entre tratamientos, pero hubo una diferencia en pH promedio del ensilaje expuesto, favorable a THO (5.30 vs 5.43 valor común en ambos THH y TCN); y una tendencia (P < 0.15) en temperatura promedio (°C) favorable a THH (29.61 vs 30.26 en THO y 30.28 en TCN). En general, el uso de los inóculos de BPAL en ensilaje de maíz tropical no resultó en grandes diferencias relativo a ensilaje no inoculado en las variables dependientes en estudio relativo a características fermentativas y EA.

Thirty Years of Land-cover Change in Bolivia

Land-cover change in eastern lowland Bolivia was documented using Landsat images from five epochs for all landscapes situated below the montane tree line at approximately 3000 m, including humid forest, inundated forest, seasonally dry forest, and cloud forest, as well as scrublands and grasslands. Deforestation in eastern Bolivia in 2004 covered 45 411 km2, representing;9% of the original forest cover, with an additional conversion of 9042 km2 of scrub and savanna habitats representing 17 % of total historical land-cover change. Annual rates of land-cover change increased from;400 km2 y1 in the 1960s to;2900 km2 y1 in the last epoch spanning 2001 to 2004. This study provides Bolivia with a spatially explicit information resource to monitor future land-cover change, a prerequisite for proposed mechanisms to compensate countries for reducing carbon emissions as a result of deforestation. A comparison of the most recent epoch with previous periods shows that policies enacted in the late 1990s to promote forest conservation had no observable impact on reducing deforestation and that deforestation actually increased in some protected areas. The rate of land-cover change continues to increase linearly nationwide, but is growing faster in the Santa Cruz department because of the expansion of mecha-nized agriculture and cattle farms

Determining puma habitat suitability in the Eastern USA

Pumas (Puma concolor) were eliminated from most of the eastern USA a century ago. In the past couple of decades, their recovery in the West has increased puma dispersal into the Midwest, with some individuals even traveling to the East Coast. We combined published expert opinion data and a habitat suitability index in an analysis that identified 17 areas in the Upper Midwest, Ozarks, Appalachia, and New England that could potentially host puma populations in the future. Thirteen of these were larger than 10,000 km2 and so likely to ensure a puma population’s long-term genetic health. Further, we quantified patch size, human density, livestock density, percent public land, and a sociocultural index reflecting wildlife values for comparing patches, as well as present a summary of current legislation relevant to puma management in the East. Our work may be useful in identifying suitable areas to restore pumas based not only on the quality of their biophysical habitat, but also on social values conducive to puma-human coexistence

América Latina. Los derechos y las prácticas ciudadanas a la luz de los movimientos populares

A partir, fundamentalmente, de los análisis de caso y los datos que ha sistematizado el Observatorio Social de América Latina (OSAL), nuestra propuesta gira en torno a dos preguntas centrales: ¿qué características presenta la noción de ciudadanía en las luchas sociales latinoamericanas recientes?, y ¿qué importancia adquiere dicha dimensión para la consecución de un propósito democrático? Buscando responder ambas, hemos dividido la exposición en tres apartados. En el primero se exploran los elementos que han favorecido el reposicionamiento de la noción de ciudadanía, dentro del horizonte y discurso de las movilizaciones que a partir del año 2000 han aparecido en distintos puntos del subcontinente. En el segundo, se examinan las características más relevantes que desde nuestro punto de vista hilvanan su diversidad. Y, finalmente, en el último se desarrollan las razones por las cuales consideramos que la noción de ciudadanía ocupa un lugar estratégico en la lucha social latinoamericana de este inicio de milenio.Presentación | 9 Lucha social y derechos ciudadanos en América Latina Margarita Favela Gavia y Diana Guillén | 21 Conflictos y tensiones en torno del Estado ampliado en América Latina: Brasil y México entre la crisis orgánica del Estado y el problema de la hegemonía Lucio Oliver | 51 Movimiento-partido: el caso del Movimiento de los Trabajadores sin Tierra (MST) en Brasil Adelita Neto Carleial | 81 Seguridad alimentaria y diseño de nuevos espacios públicos en Brasil Elza Maria Franco Braga | 111 Democracia y ciudadanía en el movimiento lopezobradorista Carlos Figueroa Ibarra y Octavio H. Moreno | 129 Venciendo el miedo: retoños de movimientos sociales en el contexto de la recuperación democrática en Perú (2000-2006) Fabiola Escárzaga | 155 Reflexiones sobre la democracia y el significado de un gobierno de los movimientos sociales en Bolivia Dunia Mokrani Chávez | 191 Entre la izquierda partidista y la izquierda social: el movimiento étnico maya y las opciones político-partidistas en Guatemala Luis Fernando Mack, Máximo Ba Tiul e Ivonne Solórzano | 215 Movimiento social y proceso político en Haití (1986-2006) Alejandro Álvarez Martínez | 24

Systematic review of soil ecosystem services in tropical regions

Soil ecosystem service (SES) approaches evidence the importance of soil for human well-being, contribute to improving dialogue between science and decision-making and encourage the translation of scientific results into public policies. Herein, through systematic review, we assess the state of the art of SES approaches in tropical regions. Through this review, 41 publications were identified; while most of these studies considered SES, a lack of a consistent framework to define SES was apparent. Most studies measured soil natural capital and processes, while only three studies undertook monetary valuation. Although the number of publications increased (from 1 to 41), between 2001 and 2019, the total number of publications for tropical regions is still small. Countries with the largest number of publications were Brazil (n = 8), Colombia (n = 6) and Mexico (n = 4). This observation emphasizes an important knowledge gap pertaining to SES approaches and their link to tropical regions. With global momentum behind SES approaches, there is an opportunity to integrate SES approaches into policy and practice in tropical regions. The use of SES evaluation tools in tropical regions could transform how land use decisions are informed, mitigating soil degradation and protecting the ecosystems that soil underpins