51 research outputs found
Forest dynamics following spruce budworm outbreaks in the northern and southern mixedwoods of central Quebec
The effects of 20th century spruce budworm (Choristoneura fumiferana (Clem.)) outbreaks on forest dynamics was examined in the southern and northern parts of the mixedwood forest zone in central Quebec, Canada. In each region, three study areas were placed in unmanaged stands that had not burned for more than 200 years. Disturbance impacts and forest succession were evaluated using aerial photographs and dendrochronology. Spruce budworm outbreaks occurred around 1910, 1950, and 1980 in both regions. The 1910 outbreak seemed to have limited impact in both regions, and the 1950 outbreak caused heavy mortality in conifer stands (mostly of balsam fir, Abies balsamea (L.) Mill.) in the southern region. The 1980 outbreak caused major mortality in the northern region, but had little impact in the southern region. Successive spruce budworm outbreaks led to a massive invasion by hardwood species in the last century in the southern region but not in the northern region. The reason for such contrasting dynamics between regions is unknown, but we hypothesize that differences in disturbance intensities, influenced by climate, played a major role. Results from this study emphasize that generalizations about the effect of spruce budworm outbreaks on forest dynamics cannot be derived from observations made during a single outbreak or at a single location
Hamiltonian dynamics and Noether symmetries in Extended Gravity Cosmology
We discuss the Hamiltonian dynamics for cosmologies coming from Extended
Theories of Gravity. In particular, minisuperspace models are taken into
account searching for Noether symmetries. The existence of conserved quantities
gives selection rule to recover classical behaviors in cosmic evolution
according to the so called Hartle criterion, that allows to select correlated
regions in the configuration space of dynamical variables. We show that such a
statement works for general classes of Extended Theories of Gravity and is
conformally preserved. Furthermore, the presence of Noether symmetries allows a
straightforward classification of singularities that represent the points where
the symmetry is broken. Examples of nonminimally coupled and higher-order
models are discussed.Comment: 20 pages, Review paper to appear in EPJ
EUPRON: nursesâ practice in interprofessional pharmaceutical care in Europe. A cross-sectional survey in 17 countries
Abstract Objectives Safe pharmaceutical care (PC) requires an interprofessional team approach, involving physicians, nurses and pharmacists. Nursesâ roles however, are not always explicit and clear, complicating interprofessional collaboration. The aim of this study is to describe nursesâ practice and interprofessional collaboration in PC, from the viewpoint of nurses, physicians and pharmacists. Design A cross-sectional survey. Setting The study was conducted in 17 European countries, each with their own health systems. Participants Pharmacists, physicians and nurses with an active role in PC were surveyed. Main outcome measures Nursesâ involvement in PC, experiences of interprofessional collaboration and communication and views on nursesâ competences. Results A total of 4888 nurses, 974 physicians and 857 pharmacists from 17 European countries responded. Providing patient education and information (PEI), monitoring medicines adherence (MMA), monitoring adverse/therapeutic effects (ME) and prescribing medicines were considered integral to nursing practice by 78%, 73%, 69% and 15% of nurses, respectively. Most respondents were convinced that quality of PC would be improved by increasing nursesâ involvement in ME (95%), MMA (95%), PEI (91%) and prescribing (53%). Mean scores for the reported quality of collaboration between nurses and physicians, collaboration between nurses and pharmacists and interprofessional communication were respectively <7/10, â€4/10, <6/10 for all four aspects of PC. Conclusions ME, MMA, PEI and prescribing are part of nursesâ activities, and most healthcare professionals felt their involvement should be extended. Collaboration between nurses and physicians on PC is limited and between nurses and pharmacists even more
Can forest management based on natural disturbances maintain ecological resilience?
Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance
Evolution of microstructure and crystallographic texture during dissimilar friction stir welding of duplex stainless steel to low carbon-manganese structural steel
Electron backscattered diffraction (EBSD) was used to analyze the evolution of microstructure and crystallographic texture during friction stir welding of dissimilar type 2205 duplex stainless steel (DSS) to type S275 low carbon-manganese structural steel. The results of microstructural analyses show that the temperature in the center of stirred zone reached temperatures between Ac 1 and Ac 3 during welding, resulting in a minor ferrite-to-austenite phase transformation in the S275 steel, and no changes in the fractions of ferrite and austenite in the DSS. Temperatures in the thermomechanically affected and shoulder-affected zones of both materials, in particular toward the root of the weld, did not exceed the Ac 1 of S275 steel. The shear generated by the friction between the material and the rotating probe occurred in austenitic/ferritic phase field of the S275 and DSS. In the former, the transformed austenite regions of the microstructure were transformed to acicular ferrite, on cooling, while the dual-phase austenitic/ferritic structure of the latter was retained. Studying the development of crystallographic textures with regard to shear flow lines generated by the probe tool showed the dominance of simple shear components across the whole weld in both materials. The ferrite texture in S275 steel was dominated by D 1, D 2, E, EÂŻ , and F, where the fraction of acicular ferrite formed on cooling showed a negligible deviation from the texture for the ideal shear texture components of bcc metals. The ferrite texture in DSS was dominated by D 1, D 2, I, IÂŻ , and F, and that of austenite was dominated by the A, AÂŻ , B, and BÂŻ of the ideal shear texture components for bcc and fcc metals, respectively. While D 1, D 2, and F components of the ideal shear texture are common between the ferrite in S275 steel and that of dual-phase DSS, the preferential partitioning of strain into the ferrite phase of DSS led to the development of I and IÂŻ components in DSS, as opposed to E and EÂŻ in the S275 steel. The formations of fine and ultrafine equiaxed grains were observed in different regions of both materials that are believed to be due to strain-induced continuous dynamic recrystallization (CDRX) in ferrite of both DSS and S275 steel, and discontinuous dynamic recrystallization (DDRX) in austenite phase of DSS
Actinide partitioning-transmutation program final report. VII. Long-term risk analysis of the geologic repository
This report supports the overall assessment by Oak Ridge National Laboratory of actinide partitioning and transmutation by providing an analysis of the long-term risks associated with the terminal storage of wastes from a fuel cycle which incorporates partitioning and transmutation (P-T) and wastes from a cycle which does not. The system model and associated computer code, called AMRAW (Assessment Method for Radioactive Waste), are used for the analysis and are applied to the Los Medanos area in southeastern New Mexico. Because a conservative approach is used throughout, calculated results are believed to be consistently higher than reasonable expectations from actual disruptive incidents at the site and therefore are not directly suited for comparison with other analyses of the particular geologic location. The assessment is made with (1) the probabilistic, or risk, mode that uses combinations of reasonable possible release incidents with their probability of occurrence distributed and applied throughout the assessment period, and (2) the consequence mode that forces discrete release events to occur at specific times. An assessment period of 1 million years is used. The principal results are: (1) In all but the expulsive modes, /sup 99/Tc and /sup 129/I completely dominate cumulative effects based on their transport to man through leaching and movement with groundwater, effecting about 33,000 health effects (deaths) over the 1 million years; (2) P-T has only limited effectiveness in reducing long-term risk from a radionuclide waste repository under the conditions studied, and such effectiveness is essentially confined to the extremely unlikely (probability of occurrence 10/sup -12//year) expulsive events; (3) Removal or immobilization of /sup 99/Tc and /sup 129/I might provide benefits sufficiently tangible to warrant special consideration
A incidĂȘncia de cirurgias na população de RibeirĂŁo Preto, SP, Brasil Incidence of surgery in RibeirĂŁo Preto, SP, Brazil
Foi estudada a incidĂȘncia de cirurgias na população residente em RibeirĂŁo Preto, SĂŁo Paulo (Brasil), em 1975, em relação Ă idade, sexo, categoria de internação do paciente e tipo de internação cirĂșrgica, utilizando-se as informaçÔes coletadas por um Centro de Processamento de Dados Hospitalares. Foram observadas elevadas taxas de cirurgias: 79,8/1000 no sexo feminino e 43,8/1000 no masculino. As intervençÔes obstĂ©tricas representaram 31,8% do total de operaçÔes realizadas; no sexo masculino as intervençÔes ortopĂ©dicas foram as de maior incidĂȘncia. A proporção de internaçÔes com ocorrĂȘncia de cirurgia foi mais elevada nos pacientes particulares. As operaçÔes ortopĂ©dicas e plĂĄsticas incidiram relativamente mais nos beneciĂĄrios da PrevidĂȘncia Social e nos indigentes, enquanto que as otorrinolĂłgicas e urolĂłgicas foram proporcionalmente mais freqĂŒentes nos pacientes particulares.<br>This paper reports on surgical rates as related to patient's ages sex and categories of hospitalization in the population of RibeirĂŁo Preto, S. Paulo, Brazil. Data were obtained from a hospital information center. The surgical rate in RibeirĂŁo Preto was similar to the highest rates reported in literature. Obstetric surgery accounted for 31.8% of all operations performed. Orthopedic operations were the most frequent kind of surgery performed on the male sex. Hospitalization with surgery was more frequent in the patients whose care was remunerated. The number of orthopedic and plastic surgical operations was greater in the case of Social Insurance and indigent patients, whereas otorrinological and urinary tract operations were more frequent in the case of paying patients
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