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The X 2 holder enables the effective production of thin, electron transparent samples for high-resolution transmission electron microscopy (HRTEM). Improvements to the X 2 holder for high-quality transmission electron microscopy (TEM) sample preparation are presented in this paper. We discuss the influence of backscattered electrons (BSE) from the sample holder in determining the lamella thickness in situ and demonstrate that a significant improvement in thickness determination can be achieved by comparatively simple means using the relative BSE intensity. We show (using Monte Carlo simulations) that by taking into account the finite collection angle of the electron backscatter detector, an approximately 20% underestimation of the lamella thickness in a silicon sample can be avoided. However, a correct thickness determination for light-element lamellas still remains a problem with the backscatter method; we introduce a more accurate method using the energy dispersive X-ray spectroscopy (EDX) signal for in situ thickness determination. Finally, we demonstrate how to produce a thin lamella with a nearly damage-free surface using the X 2 holder in combination with sub-kV polishing in the Fischione Instruments׳ NanoMill ® TEM specimen preparation system. [ABSTRACT FROM AUTHOR]

The understanding of the spatial structure and dynamics of populations can guide conservation decisions, but studies of this type focused on small (< 7-kg) carnivores are rare. We compared survival, reproduction, and dispersal of radiocollared Geoffroy's cats ( Leopardus geoffroyi) in a protected area and adjacent cattle ranches in Argentina to assess the effects of livestock management and its associated disturbances (i.e., hunting by humans) on the demography of this felid. Thirteen cats in the park and 13 in the ranches were radiotracked for up to 556 days in 2007-2008. We evaluated the Geoffroy's cat population trajectory at the landscape level using a stage-structured, stochastic matrix model based on our estimated vital rates. The study occurred during a prolonged drought, likely affecting estimated vital rates. Survival in the ranches was 52% lower than in the park; mortalities were due to intraguild predation in the park and were human-related in the ranches. Dispersal from the ranches was 32% lower than from the park and dispersal distances were up to 128 km. The number of cubs per litter was similar between areas. Assuming persistence of drought conditions and estimated vital rates, the simulated metapopulation rapidly collapsed and cat survival on ranches was the vital rate to which the model was most sensitive. Because projected climatic scenarios predict increased drought frequency for the region, we explored management options that would enhance chances of persistence, simulating 2 'adaptation' strategies: hunting restrictions on ranches and expanding protected areas. More than doubling of cat survival on ranches or a 9-fold increase in protected area extension would be required, involving major investments, to avoid the extinction of this cat metapopulation if droughts become prevalent. Our analysis may be helpful to improve our predictive capacity to identify new threats and facilitate adaptation strategies for Geoffroy's cat or other similar carnivores. La comprensión de la estructura espacial y la dinámica de las poblaciones pueden guiar decisiones de conservación, pero los estudios de este tipo centrados en pequeños carnívoros (< 7 kg) son raros. Se comparó la supervivencia, reproducción y dispersión de gatos monteses ( Leopardus geoffroyi) equipados con radiocollar en una zona protegida y campos ganaderos adyacentes en Argentina, para evaluar los efectos del manejo ganadero y sus disturbios asociados (p.e., la cacería) sobre la demografía de este felino. Trece gatos en el parque y 13 en los campos fueron monitoreados por hasta 556 días durante 2007-2008. Se simuló la trayectoria de la población monitoreada a nivel del paisaje utilizando un modelo matricial estocástico estructurado por edades, basado en las tasas vitales estimadas. El estudio tuvo lugar durante una sequía prolongada, lo que probablemente afectó las tasas vitales estimadas. La supervivencia de los gatos en los campos fue 52% menor que en el parque; la mortalidad se debió a depredación intragremio en el parque y estuvo mayormente relacionada al hombre en los campos. La dispersión desde los campos fue 32% menor que desde el parque y las distancias de dispersión fueron de hasta 128 km. El número de crías por camada fue similar entre áreas. Asumiendo la persistencia de la sequía prolongada y las tasas vitales estimadas, la metapoblación simulada declinó rápidamente, siendo la supervivencia de los gatos en los campos la tasa vital más sensible para el modelo. Dado que los escenarios climáticos proyectados predicen una mayor frecuencia de sequías para la región, se exploraron opciones de manejo para mejorar las posibilidades de persistencia de esta población, simulando dos 'estrategias de adaptación': restricciones de cacería en los campos y ampliación del área protegida en el paisaje estudiado. Para evitar la extinción de esta metapoblación si las sequías se hacen frecuentes, sería necesario incrementar a más del doble la supervivencia de los gatos en los campos o aumentar 9 veces la extensión de superficie protegida en el paisaje, lo que implica importantes inversiones de manejo. Nuestro análisis puede ser útil para mejorar la capacidad de predicción en la identificación de nuevas amenazas y para facilitar estrategias de adaptación para el gato montés u otros carnívoros similares. [ABSTRACT FROM AUTHOR]

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Los ambientes costeros de dunas son ecosistemas complejos con una variación interna elevada y una extensa zonación de la vegetación a lo largo de la línea de costa. La costa norte del Golfo San Matías presenta un sistema de dunas donde la vegetación se distribuye en un gradiente desde la costa. Dicha vegetación está caracterizada por comunidades psammófitas hasta estepas arbustivas xerófitas. Los objetivos de este trabajo fueron 1) describir las principales comunidades vegetales del sitio de estudio, y 2) analizar la asociación entre las comunidades vegetales y las unidades geomorfológicas. Se realizaron 16 censos de vegetación con cuatro réplicas en cada unidad geomorfológica. El análisis de la vegetación realizado permitió describir tres comunidades vegetales. La asociación entre la heterogeneidad florística y las cuatro unidades geomorfológicas de Bajo de la Quinta se vincula principalmente con las características del sustrato.

A escritora Hélia Correia, com a sua obra Montedemo, presenteia -nos com uma mulher que sofre uma metamorfose, passando de femme fragile a femme fatale. Esta transformação tem a ver com a força que emana do centro de Montedemo, pois uma indeterminação sobrenatural torna -o no local do desassossego moral, da perdição das almas – o monte do demo. E é nessa natureza que Milena, a protagonista, se abandona aos prazeres da carne, se deixa fertilizar e se metamorfoseia numa mulher sensual e erótica.

El monte de sierras y bolsones es uno de los ambientes áridos menos explorado a nivel de especies de aves. Asthenes steinbachi, Pseudoseisura gutturalis ochroleuca, Teledromas fuscus y Poospiza ornata presentes en este ambiente, son especies endémicas de Argentina, categorizadas como vulnerables a nivel nacional. El objetivo de este trabajo es actualizar su distribución y aportar información sobre su presencia en nuevas localidades de las provincias de Catamarca y La Rioja, y sobre su abundancia, aspectos bioló- gicos y ecológicos. En Catamarca se realizaron 203 transectas de faja, 82 puntos de radio fijo, y 50 hs de observaciones al azar, registrando 58 individuos de Teledromas fuscus, 20 Pseudoseisura gutturalis ochroleuca y 2 Poospiza ornata. En La Rioja, se realizaron 308 transectas de faja y 20 hs de observaciones al azar, identificando 17 Asthenes steinbachi, 18 Pseudoseisura gutturalis ochroleuca, 12 Teledromas fuscus y 16 Poospiza ornata. Se examinaron además ejemplares depositados en la Colección Ornitológica de la Fundación Miguel Lillo (COFML), Tucumán y se revisaron antecedentes bibliográficos para completar los datos aportados. Se pudo establecer nuevas localidades de distribución y se aportan datos sobre la abundancia, aspectos biológicos y ecológicos de estas cuatro especies endémicas en Catamarca y La Rioja, relacionando la información obtenida con datos de colección y datos bibliográficos. Este trabajo puede servir de base para futuras investigaciones poblacionales que busquen establecer categorías de conservación en especies endémicas de Monte.

Varela, Rodolfo Omar; Gloria S. Jaime. 2010. “Nota sobre la estructura poblacional de árboles en la llanura de Los Mogotes Colorados, La Rioja, Argentina”. Lilloa 47 (1-2). Se analiza la estructura poblacional de árboles en la llanura al este de Los Mogotes Colorados (extremo norte), en el centro-oeste de la Provincia de La Rioja. La vegetación es una estepa arbustiva con árboles dispersos, donde predominan especies de la región del Monte. En 10 parcelas de 10 x 100 m (= 1 ha), se contaron 77 árboles (área basal = 1,75 m2) y 117 renuevos de tres especies. El 90% de los árboles y el 66% de los renuevos corresponden a Aspidosperma quebracho-blanco (Apocynaceae), representado en todas las clases diamétricas y con renuevos en todas las clases de alturas. Los resultados demuestran que el quebracho blanco, especie típica del Chaco árido, es el árbol más abundante, con mayor capacidad de regeneración. Esto indica que la llanura estudiada es un ecotono entre la región del Monte y el Chaco árido. La expansión del quebracho-blanco en el valle Antinaco-Los Colorados es probablemente motivada por incrementos en la precipitación de la región.

ABSTRACT This paper provides a detailed analysis of thorn lesions found in lower limb elements of a modern osteological collection of guanaco ( Lama guanicoe). Four types of lesions were recorded: (1) thorns visible on the bone surface, (2) bony reaction with relief, (3) small negative scars and (4) medium negative scars. The methods used to recognise, record and quantify these lesions are presented. As a result, 35 of the 36 individuals analyzed contained one or more types of lesions. The highest concentrations of lesions were recorded on the anterior view of the metacarpal shafts. All the age ranges were affected by lesions; however, individuals between the ages of 1 and 3 years were the most affected, whereas those between the ages of 0 and 1 year contained the least amount of lesions. To provide examples of how thorn lesions can be identified and used as a paleoenvironmental proxy in the fossil record, we analyzed two archaeological sites from different phytogeographic provinces: Bajo de la Quinta (Monte phytogeographic province) and Calera (Pampa phytogeographic province). Results found that 25% of the elements from the Bajo de la Quinta site contained lesions, whereas none of the elements from the Calera site showed evidence of lesions. When detectable in the fossil record, thorn lesions can provide an indirect approximation of the paleoenvironment. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In central-western Argentina, there is a pronounced water deficit gradient, from semiarid climate conditions with 500-mm rainfall/year to arid climate conditions with 80-mm rainfall/year. This climatic transition, governed by the rainfall gradient, occurs between the Arid Chaco and Monte phytogeographic regions and is evidenced by differences in vegetation type, structure, dynamics and tree growth. In turn, the availability of soil moisture, particularly access to the water table, modifies water use strategies by trees along this gradient. We analyzed how water availability, expressed as differences in accessibility to the water table, influences Prosopis flexuosa tree rings along a precipitation gradient. In this manner, we try to interpret the growth of species according to the use of differential water sources. P. flexuosa showed highly varying growth reactions (tree-ring width and hydraulic anatomic parameters) with climate, depending on the ecology of the site. Along the Arid Chaco-Monte gradient, the growth of P. flexuosa is more dependent on variations in rainfall in those areas where water depth is greater than root spread. The climate signal was hidden in those regions where the water table is accessible to the root system. [ABSTRACT FROM AUTHOR]

The scarab beetle genus Pseudogeniates Ohaus (Scarabaeidae: Rutelinae: Rutelini) is endemic to Argentina. The genus includes three species: P. cordobaensis Soula, P. intermedius Ohaus, and P. richterianus Ohaus. We characterize the genus, provide a key to species, redescribe and diagnose each species, provide spatial and temporal distributions, and discuss distributions of the species in relation to eco-regions and areas of endemism in Argentina. [ABSTRACT FROM AUTHOR]

Abstract: Many of the complex issues worldwide regarding environmental management and sustainable develo-pment require integrating the social and natural sciences. Nevertheless, while theoretical discussions have been increasingly developed, operative issues are still major barriers to integrated social–ecological analysis. The aim of this paper was to assess regional forage production in semi-arid rangelands as a key feature in social-ecological analysis, by using human organizational units (i.e. counties). We used these state-administrative units to explore demographic and farming indicators in order to address socio-productive implications of different regional forage production dynamics. We studied the forage spatial and temporal dynamics in two different large ecological regions: Monte and Patagonia, under a single administrative unit (i.e. province). Since forage production estimations in arid rangelands are not trivial, we tested two different methods. We found that inter-annual variability in forage production explained the main differences between regions. At a regional level, zones with higher temporal variability in forage production registered less rural residents and farm numbers, but inverse situations were registered at sub-regional scales. We found a non-linear relationship between forage production variability and rural population density. We proposed differentiated policy recommendations regarding rangeland management and animal husbandry, considering both the social and ecological contexts. [Copyright &y& Elsevier]

The pricing of mortgages in the context of stochastic interest rate plays an important role for financial management. The contributing factors impacting the mortgage contract value have been explored by abundant literatures. However, the market players anticipate a systematic but low-cost approach to minimize the net present value of the payment streams by taking advantage of refinancing, for instance. This paper focuses on finding a desirable refinancing time for mortgage borrowers to minimize the total payment in a stochastic interest rate environment. The underlying interest rate is assumed to follow a stochastic process with mean-reverting property, the setting of which is broad enough to accommodate a large spectrum of market realities. Two types of commonly adopted mortgage balance settlement schemes are analyzed and compared to ensure the applicability of our study. Our numerical algorithm is validated with with varying samplings, leading to several interesting characteristics pertaining to the optimal mortgage refinancing period. As one of the applications, we obtain the optimal boundary conditions for the value of the mortgage contract for all time before the expiry of the contract. Our approach and algorithm provide cost effective and easy to use financial tools for both institutional and individual property investors. [ABSTRACT FROM AUTHOR]

In this study 85 plant species involved in home medicine of a rural community are recorded. This community is stated in NW La Pampa (Argentina) in the transitional area between Pampa and Cuyo region. Etiological and therapeutical interpretations of the diseases are studied by means of open and semi-structured interviewees made with male and female adults. Social actors who perform the skill of healing as soon as the present state of the traditional botanical knowledge regarding to home medicine are described too. The greatest diversity of uses belongs to the most abundant species and they are related to respiratory, digestive, urinary and orthopedic diseases. Processes of erosion related to the Hippocratic model of the traditional medicine become evident in contrast to other rural communities of South America as well as in supernatural therapies where religious symbols and rituals take part. [ABSTRACT FROM AUTHOR]

Prosopis flexuosa trees dominate woodlands in the Central Monte Desert (Mendoza, Argentina), with <200 mm rainfall, exploiting the water table recharged by Andean rivers, and also growing in dunes with no access to the water table. Prosopis woodlands were extensively logged during development of the agricultural oasis, and surface and groundwater irrigation could lower the depth of the water table in the future. We evaluated tree populations with decreasing access to the water table: valley adult trees, valley saplings, and dune adult trees, in order to assess their ecophysiological response to water table accessibility. High and seasonally stable pre-dawn leaf water potentials (−2.2 ± 0.2 to −1.2 ± 0.07 MPa) indicated that valley adults utilize larger and more stable water reservoirs than valley saplings and dune adults (−3.8 ± 0.3 to −1.3 ± 0.07 MPa), with higher midday leaf conductance to water vapor (valley adults ~250; dune adults <60 mmol m s), potentially higher CO uptake, and increased radial growth rate (valley adults 4.1 ± 0.07; dune adults 2.9 ± 0.02 mm year). Trees with poor access to the water table exhibited drought tolerance responses such as midday stomata closure, leaflet closure, and osmotic adjustment. Stomata density decreased in response to drought when leaf expansion was restricted. The combination of phreatophytism and drought tolerance would enlarge P. flexuosa habitats and buffer populations against changes in rainfall dynamics and water table depth. [ABSTRACT FROM AUTHOR]

The article discusses a study on the South American dung beetle genus Ennearabdus Lansberge. The descriptions, diagnosis and illustrations for the species of E. lobocephalus are presented which is also the only known species in the genus. A lectotype for Onthophagus lobocephalus Harold is designated and the biology, biogeography, conservation status, and distribution for E. lobocephalus are discussed.

The article presents information on the lectotypes and neotypes of different species of beetle, Eucranium found in South America. It mentions about the lectotype, Eucranium pulvinatum, Eucranium planicolle and neotype, Eucranium lepidum. It further presents information on all species of the genus, Eucranium including species belenae, cyclosoma and planicolle, their order of distribution in South America and different practices of their conservation.

Copyright of Recursos Rurais is the property of Universidad de Santiago de Compostela, Servicio de Publicaciones and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The Monte is a biogeographic province covers an extensive area from the subtropical northern part of Argentina at 24 degrees south, to the temperate northern region of Patagonia at 44 degrees south. Within the province, which is about 2000km from north to south, lies the Monte Desert, on a strip of land that stretches along the eastern side of the Andes Mountains. The definition of the boundaries of the Monte Desert varies among authors. We present a division of the Monte Desert into three botanical districts: Northern, Eremean, and Southern districts. The Northern and the Southern districts are divided into subdistricts. Different hypotheses have been proposed for the origin of the Monte Desert biota. A few plant genera show a remarkable phylogenetic affinity with plants of the North American deserts of Mojave and Sonora. However, this is an exception because most of the remaining plants, arthropods, and reptiles have an origin more closely related to the biota of the Chaco and Patagonia. Second in importance is the group of taxa that originated in Patagonia, and the most enigmatic of all are the paleoendemic groups composed of relictual taxa of Pangeic or Gondwanic origin. The complexity of the biota of the Monte desert biota is probably a result of the extensive area of contact between the two South American biotas of South America: Brazilian biota (or tropical biota) and Patagonian biota. [Copyright &y& Elsevier]

Abstract: Microcavia australis is a semifossorial, diurnal and social rodent, native to South America. The objective was to determine and compare the composition of social groups, mating system and social behaviours of cavies in two populations of the Monte (El Leoncito and Ñacuñán). The two sites differ in climate conditions and plant resource availability. Trapping was carried out on 7–11 consecutive days at three times of the year (food abundance, food shortage, reproduction), from 2003 to 2005. Individuals were identified with metal ear tags. Continuous focal samplings were performed during 4 days. The female/male proportion per group was 1/1 at both sites which, together with the absence of sexual dimorphism in body size (0.94), the accomplishment of oestrus synchronization, the large size of scrotal testes during the reproductive season and sexual patterns, suggests a promiscuous mating system. Social groups were larger and with more adults at the site with more severe climate conditions (El Leoncito). The index of association among individuals was higher at El Leoncito. Cavies could use seismic communication to avoid encounters ending in fights at El Leoncito, and the agonistic behaviour was significantly lower in this population. [Copyright &y& Elsevier]

Abstract: Oak woodland dehesa suffers from the aging of trees without a natural regeneration of young oaks coming in to replace them. Recent European Union (EU) policy reforms for rural development focus on supporting multifunctional agriculture that complies with the EU''s environmental goals, such as mitigating biodiversity losses and climate change. Such reforms could result in government support for natural woodland regeneration practices in European agroforestry systems, which are recognized for providing valuable environmental services. Managing dehesa cork oak and holm oak woodlands to stimulate the growth of new oaks could be an efficient option for maintaining, and even increasing, the dehesa''s current carbon stock and biodiversity. Here we develop and apply a new agroforestry accounting system based on the concept of Hicksian income to a dehesa in the Monfragüe area of western Spain, using primary microeconomic data from a large case study. Private total income and profitability rates are measured for individual goods and services, and for the entire dehesa in a steady state. Our application extends the EU system of accounts for agriculture and forestry by including private amenity consumption by landowners and the gain or loss in human-made and natural capital. We compare an actual typical unsustainable woodland management scenario with an ideal sustainable management scenario in which there is a continuous regeneration and recruitment of holm and cork oaks as predicted by silvicultural models. The results show that, given current land use policy incentives, allowing a slow depletion of oak trees is more profitable for a dehesa private landowner than maintaining the dehesa''s trees. As a result many dehesa environmental services are gradually lost. This market failure requires new land use policies that induce private land owners to invest in the renewal of aging oak woodlands. To evaluate the impacts of this new policy, we show how private landowner income is affected when changes are made to achieve sustainable management of dehesa oaks. More research is needed in order to understand how the dehesa''s landowner market income and private amenities trade-off can affect the owner''s land use preferences and decisions. [Copyright &y& Elsevier]

This article analyzes three maps included in a lawsuit between two people who solicited a land grant (merced) in the Province of Santa Marta at the end of the eighteenth century. The land grants were part of a series of measures that sought to reorder the territory recently expropriated from the Chimila Indians in order to reinforce colonial control over it. The manner in which the maps produced geometric space, defined by private property, was by the system of metes and bounds. But despite this shared order, differences between the maps reveal how people used them to suit to their legal interests. Based on the enigmatic figure of the 'forest', the article explores the limits of colonial cartography. While 'metes and bounds' signified territorial order, the 'forest' implied disorder. [ABSTRACT FROM AUTHOR]

Until now, knowledge regarding the mayo indians of Sinaloa, Mexico, has largely dependend on studies of the sonoran indians of the same name. This article presents ethnographic information regardig aspects of the mayo's regional situation and ethnicity. For this I will examine the historical conformation giving special attention to the group's transition from semi nomad practices to full sedentary communities, as well as the present day circumstances and their links to agricultural practices. [ABSTRACT FROM AUTHOR]

A hierarchical, two-stage approach to ab initio protein structure prediction is presented and applied to four α-helical proteins. In the first stage, a bank of low-resolution models is generated using a highly simplified protein representation and energy function, coupled with a Conformation-Family Monte Carlo (CFMC) search for the energy minimum. For helical proteins, this procedure (referred to as REPACK) produces a set of plausible packed arrangements of the helices, given their positions in the amino acid sequence. Secondary structure prediction methods such as JPRED can be used to provide the secondary structure assignment. In the second stage, these packing arrangements are used as starting points for a new search method (Local Search), based on the Monte Carlo-with-Minimization (MCM) algorithm and a united-residue (UNRES) energy function. The focus of the Local Search is mainly on improving loop conformations and side-chain positions, with minor modifications to the overall packing of the helices. By reducing the size of the conformational space that must be sampled with the UNRES energy function, which is much more expensive to compute than the REPACK energy function, this prediction scheme can be applied to much larger proteins than were tractable in the past with other UNRES-based search methods. It was applied successfully to a 224-residue protein (target T0198, PDB code 1SUM) in the sixth community-wide blind-prediction experiment on the Critical Assessment of techniques for protein Structure Prediction (CASP6). [ABSTRACT FROM AUTHOR]

We examined the numerical and spatial responses of Geoffroy's cats (Oncifelis geoffroyi) to a prey decline in central Argentina between April 2002 and November 2003. The 2nd year of fire study coincided with a severe drought. Relative abundunce of brown hares (Lepus europaeus) declined from 5.6 individuals/10 km during the predrought period to about 0.6 individuals/10 km during the drought. Small-rodent biomass also showed the lowest level for the study area during the drought of 2002-2003 ( 134.5 g/ha). During the predrought and drought periods, 3 male and 1 female, and 1 male and 9 female Geoffroy's cats, respectively, were radiotagged and monitored. Home ranges for males of the predrought period averaged 202.8 ha ± 156.8 SD and that of the single female was 27.3 ha. During the drought period, 4 females occupied an average home range of 254.9 ± 254.1 ha, and the home-range size of the single predrought female increased by a factor of 2. No obvious change in mean daily distance involved between the 2 periods was observed. Geoffroy's cats predominantly used habitats of dense cover during the predrought period, but they became more habitat generalists during the drought. Recruitment of juveniles was only recorded during the predrought period, and all monitored Geoffroy's cats dispersed or died of starvation after the prey decline. Consequently, density of Geoffroy's cats dropped from 2.9 individuals/10 km² before the drought to 0.3 individuals/10 km², probably because of food scarcity. This is the 1st study to examine the spatial ecology of a small wild eat species under nutritional (energetic) stress in South America. [ABSTRACT FROM AUTHOR]

Question: How does grazing intensity affect plant density, cover and species richness in an Patagonian arid ecosystem? Location: Monte steppe ecoregion, SW Argentina. Methods: I analysed the effect of grazing on plant density, cover and species richness using a stocking rate gradient within the same habitat. Six paddocks were used with stocking rates ranging between 0.002 - 0.038 livestock/ha. Plant density, species richness, plant cover and percentage of grazed branches were determined by sampling plots within each paddock. The percentage of grazed branches was used as an independent measurement of grazing intensity. Results: Higher stocking rates were related to lower plant density, species richness and plant cover. The paddock with the lowest grazing intensity had 86% more plants per unit area, 63% more plant cover and 48% higher species richness. The percentage of grazed branches and the quantity of dung increased with stocking rate. Conclusions: Introduced livestock seriously affect native vegetation in the Patagonian Monte. The damage observed in this xerophytic plant community suggests that plant adaptations to aridity do not provide an advantage to tolerate or avoid grazing by vertebrate herbivores in this region. Plant degradation in this arid environment is comparable to the degradation found in more humid ecosystems. [ABSTRACT FROM AUTHOR]

In desert and semidesert environments, trees generate microhabitats under their foliage originating particular edaphic and climatic conditions. Epigeic communities developing in these environments require different conditions from those of communities inhabiting beneath other plant strata or on bare soil. In this paper we present a preliminary study dealing with epigeic arthropods inhabiting under the foliage of mesquite trees (Prosopis flexuosa), in the Telteca Reserve, Mendoza, Argentina (Monte biogeographical province). Two transects with pitfall traps were checked 21 times since the summer of1994/95 until the spring of 1996. The total amount of collected specimens was 7771 grouped into 228 taxa. The community was analyzed taking into account the taxonomic groups and their seasonal changes, from which the most important in number of species and specimens were Coleoptera, composed of 23 families, Hymenoptera with 7 families, and Solifugae. These three groups represent more than 67% of the specimens collected. Of the 71 families registered, including insects and arachnids, Mutillidae (Hymenoptera) was the most numerous in number of specimens, followed by Scarabaeidae, Tenebrionidae and Elateridae (Coleoptera). The most abundant species in the soil of Telteca Reserve were Mutillidae sp. 1 (male), Elateridae sp. 1, two species of Aphodiinae (Scarabeidae), two Tenebrionidae: Megelenophorus americanus and Emmallodera hirtipes, two Hymenoptera: Plumarius sp. 1 (Plumaridae) and Scaptodactilla heterogama (female) (Mutillidae), and one spider of Zodariidae: Leprolochus birabeni. Concerning seasonal changes, spring and summer show the highest abundance for nearly all groups. The same patterns registred in other dry land studies were recognized. [ABSTRACT FROM AUTHOR]

Between august of 2000 and august of 2001 we studied the daily and seasonal activity patterns of a Liolaemus pseudoanomalus population in center -- west of Argentina, by means of censused carried out between 8:00 and 19:00 hs. We detected difference in daily an seasonal activity. The activity was not influenced by maximun and minimun temperatures and heliofany. We propose an hypothesis of seasonal activity based in reproductive event. [ABSTRACT FROM AUTHOR]

This paper describes how to apply Markov Chain Monte Carlo (MCMC) techniques to a regime switching model of the stock price process to generate a sample from the joint posterior distribution of the parameters of the model. The MCMC output can be used to generate a sample from the predictive distribution of losses from equity linked contracts, assuming first an actuarial approach to risk management and secondly a financial economics approach. The predictive distribution is used to show the effect of parameter uncertainty on risk management calculations. We also explore model uncertainty by assuming a GARCH model in place of the regime switching model. The results indicate that the financial economics approach to risk management is substantially more robust to parameter uncertainty and model uncertainty than the actuarial approach. [ABSTRACT FROM AUTHOR]

We propose a fully Bayesian approach to non-life risk premium rating, based on hierarchical models with latent variables for both claim frequency and claim size. Inference is based on the joint posterior distribution and is performed by Markov Chain Monte Carlo. Rather than plug-in point estimates of all unknown parameters, we take into account all sources of uncertainty simultaneously when the model is used to predict claims and estimate risk premiums. Several models are fitted to both a simulated dataset and a small portfolio regarding theft from cars. We show that interaction among latent variables can improve predictions significantly. We also investigate when interaction is not necessary. We compare our results with those obtained under a standard generalized linear model and show through numerical simulation that geographically located and spatially interacting latent variables can successfully compensate for missing covariates. However, when applied to the real portfolio data, the proposed models are not better than standard models due to the lack of spatial structure in the data. [ABSTRACT FROM AUTHOR]

The grain growth behaviors of TiC and WC particles in TiC-Ni, TiC-Mo2C-Ni, WC-Co and WC-VC-Co alloys during liquid phase sintering were investigated for different Ni or Co contents and compared with the results of Monte Carlo simulations. In the experimental study, TiC-Ni and WC-Co alloys had a maximum grain size at a certain liquid volume fraction, while the grain size in TiC-Mo2C-Ni and WC-VC-Co alloys increased monotonically with an increasing liquid volume fraction. These results mean that the grain growth of these alloys cannot be explained by the conventional mechanisms for Ostwald ripening, namely diffusion or reaction controlled processes. Monte Carlo simulations with different energy relationships between solidliquid interfaces predicted the effect of the liquid volume fraction on grain size similar to the experimental results. The contiguous boundaries between solid (carbide) particles appear to influence the grain growth behavior in TiC- and WC-based alloys during liquid phase sintering. [ABSTRACT FROM AUTHOR]

Norberg (1989) analyses the heterogeneity in a portfolio of group life insurances using a parametric empirical Bayesian approach. In the present paper the model of Norberg is compared to a parametric fully Bayesian model and to a non-parametric fully Bayesian model. [ABSTRACT FROM AUTHOR]