810 resultados para CLIMATES


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Mapudungun (unclassified) is spoken in south-central Chile and southwestern Argentina at different altitudes in climates ranging from tundra and subalpine to Mediterranean. This paper surveys the basic semantics and morphosyntax of nine temperature terms, of which wütre ‘cold’, füshkü ‘cool’, eñum ‘warm’ and are ‘hot’ are probably the most frequently used ones. While these terms can be used for tactile, ambient, and personal-feeling temperatures, the other five are specialised for one or two of these kinds of evaluations. Notably, all terms can be used as main verbs in predications; most can also be used as adjectives in order to modify nouns, and only wütre and are are commonly used as nouns referring to ‘cold’ and ‘heat’ respectively.

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The Alpine region is warming fast, and concurrently, the frequency and intensity of climate extremes are increasing. It is currently unclear whether alpine ecosystems are sensitive or resistant to such extremes. We subjected Swiss alpine grassland communities to heat waves with varying intensity by transplanting monoliths to four different elevations (2440–660 m above sea level) for 17 d. Half of these were regularly irrigated while the other half were deprived of irrigation to additionally induce a drought at each site. Heat waves had no significant impacts on fluorescence (Fv/Fm, a stress indicator), senescence and aboveground productivity if irrigation was provided. However, when heat waves coincided with drought, the plants showed clear signs of stress, resulting in vegetation browning and reduced phytomass production. This likely resulted from direct drought effects, but also, as measurements of stomatal conductance and canopy temperatures suggest, from increased high-temperature stress as water scarcity decreased heat mitigation through transpiration. The immediate responses to heat waves (with or without droughts) recorded in these alpine grasslands were similar to those observed in the more extensively studied grasslands from temperate climates. Responses following climate extremes may differ in alpine environments, however, because the short growing season likely constrains recovery.

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Reconstructions of the deposition rate of windblown mineral dust in ocean sediments offer an important means of tracking past climate changes and of assessing the radiative and biogeochemical impacts of dust in past climates. Dust flux estimates in ocean sediments have commonly been based on the operationally defined lithogenic fraction of sediment samples. More recently, dust fluxes have been estimated from measurements of helium and thorium, as rare isotopes of these elements (He-3 and Th-230) allow estimates of sediment flux, and the dominant isotopes (He-4 and Th-232) are uniquely associated with the lithogenic fraction of marine sediments. In order to improve the fidelity of dust flux reconstructions based on He and Th, we present a survey of He and Th concentrations in sediments from dust source areas in East Asia, Australia and South America. Our data show systematic relationships between He and Th concentrations and grain size, with He concentrations decreasing and Th concentrations increasing with decreasing grain size. We find consistent He and Th concentrations in the fine fraction (<5 μm) of samples from East Asia, Australia and Central South America (Puna-Central West Argentina), with Th concentrations averaging 14 μg/g and He concentrations averaging 2 μcc STP/g. We recommend use of these values for estimating dust fluxes in sediments where dust is dominantly fine-grained, and suggest that previous studies may have systematically overestimated Th-based dust fluxes by 30%. Source areas in Patagonia appear to have lower He and Th contents than other regions, as fine fraction concentrations average 0.8 μcc STP/g and 9 μg/g for 4He and 232Th, respectively. The impact of grain size on lithogenic He and Th concentrations should be taken into account in sediments proximal to dust sources where dust grain size may vary considerably. Our data also have important implications for the hosts of He in long-traveled dust and for the 3He/4He ratio used for terrigenous He in studies of extraterrestrial He in sediments and ice. We also investigate the use of He/Th ratios as a provenance tracer. Our results suggest differences in fine fraction He/Th ratios between East Asia, Australia, central South America and Patagonia, with ratios showing a positive relationship with the geological age of source rocks. He/Th ratios may thus provide useful provenance information, for example allowing separation of Patagonian sources from Puna-Central West Argentina or Australian dust sources. He/Th ratios in open-ocean marine sediments are similar to ratios in the fine fraction of upwind dust source areas. He/Th ratios in mid-latitude South Atlantic sediments suggest that dust in this region primarily derives from the Puna-Central West Argentina region (23–32°S) rather than Patagonia (>38°S). In the equatorial Pacific, He/Th ratios are much lower than in extratropical Pacific sediments or potential source areas measured as a part of this study (East Asia, South America, Australia) for reasons that are at present unclear, complicating their use as provenance tracers in this region.

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The European larch (Larix decidua Mill.) is a pioneer, very long-lived, fast-growing coniferous tree, which occurs in the central and eastern mountains of Europe, forming open forests or pasture woods at the upper tree limits. Larch is the only deciduous conifer in Europe as an adaptation to continental alpine climates. In fact, it is able to tolerate very cold temperatures during winter and, by losing its needles, avoids foliage desiccation. It is a transitional species, colonising open terrain after natural disturbances. It forms pure stands but more often it is found with other alpine tree species, which tend to replace it if no other disturbances occur. Thanks to its adaptability and the durability of its wood, the European larch represents an important silvicultural tree species in the alpine regions, planted even outside its natural ranges. Its wood is largely used for carpentry, furniture and pulp for paper. In lower altitudes or with high precipitation rates, larch is more susceptible to fungal diseases. Outbreaks of insect defoliators, principally caused by the larch bud moth (Zeiraphera diniana), can limit tree development, with economic losses in plantations, but they rarely lead to the death of the trees.

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Herbert E Wright Jr was one of the foremost Quaternary scientists of the last century. He made wide ranging contributions to our understanding of the late-Quaternary of North and South America, Europe, Asia and Africa. This was based largely on reconstructing palaeoenvironments from lake sediments and included the important implications for glacial, vegetational, fire and climatic history, geoarchaeology and conservation. Many of his inter-disciplinary research projects involved fieldwork with his graduate students and co-workers from the University of Minnesota where he created and led the renowned Limnological Research Center. Perhaps his most outstanding contribution was as an instigator of the Co-operative Holocene Mapping Project (COHMAP). This triggered a paradigm shift in Holocene climatic research involving the comparison of climate-model simulations of past climates with palaeoclimatic data.

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When the Shakers established communal farms in the Ohio Valley, they encountered a new agricultural environment that was substantially different from the familiar soils, climates, and markets of New England and the Hudson Valley. The ways in which their response to these new conditions differed by region has not been well documented. We examine patterns of specialization among the Shakers using the manuscript schedules of the federal Agricultural Censuses from 1850 through 1880. For each Shaker unit, we also recorded a random sample of five farms in the same township (or all available farms if there were fewer than five). The sample of neighboring farms included 75 in 1850, 70 in the next two census years, and 66 in 1880. A Herfindahl-type index suggested that, although the level of specialization was less among the Shakers than their neighbors, trends in specialization by the Shakers and their neighbors were remarkably similar when considered by region. Both Eastern and Western Shakers were more heavily committed to dairy and produce than were their neighbors, while Western Shakers produced more grains than did Eastern Shakers, a pattern imitated in nearby family farms. Livestock and related production was far more important to the Eastern Shakers than to the Western Shakers, again similar to patterns in the census returns from other farms. We conclude that, despite the obvious scale and organizational differences, Shaker production decisions were based on the same comparative advantages that determined production decisions of family farms.

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A population-based cross-sectional survey of socio-environmental factors associated with the prevalence of Dracunculus medinensis (guinea worm disease) was conducted in Idere, a rural agricultural community in Ibarapa, Oyo state, Nigeria, during 1982.^ The epidemiologic data were collected by household interview of all 501 households. The environmental data were collected by analysis of water samples collected from all domestic water sources and rainfall records.^ The specific objectives of this research were to: (a) Describe the prevalence of guinea worm disease in Idere during 1982 by age, sex, area of residence, drinking water source, religion and weekly amount of money spent by the household to collect potable drinking water. (b) Compare the characteristics of cases with non-cases of guinea worm in order to identify factors associated with high risk of infection. (c) Investigate domestic water sources for the distribution of Cyclops. (d) Determine the extent of potable water shortage with a view to identifying factors responsible for such shortage in the community. (e) Describe the effects of guinea worm on school attendance during 1980/1982 school years by class and location of school from piped water supply.^ The findings of this research indicate that during 1982, 31.8 percent of Idere's 6,527 residents experienced guinea worm infection, with higher prevalence of infection recorded in males in their most productive years and females in their teenage years. The role of sex and age to risk of higher infection rate was explained in the context of water related exposure and water intake due to dehydration from physical occupational actitives of subgroups.^ Potable water available to residents was considerably below the minimum recommended by WHO for tropical climates, with sixty-eight percent of water needs of the residents coming from unprotected surface water which harbour Cyclops, the obligatory intermediate host of Dracunculus medinensis. An association was found between periods of relative high density of Cyclops in domestic water and rainfall.^ Impact of guinea worm infection on educational activities was considerable and its implications were discussed, including the implications of the research findings in relation to control of guinea worm disease in Ibarapa. ^

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This analysis provides an emergent framework that emphasizes a neglected component of both direct practice with families and organizational development. Human emotions, both beneficial (positive emotional labor) and harmful (negative emotional labor), have received short shrift in leadership development, supervision, direct practice preparation and supports, and workforce stabilization, and professionalization. Significantly, a key indicator of negative emotional labor—secondary traumatic stress (STS)—often has been ignored and neglected, despite the fact that it may be endemic in the workforce. STS typically results from traumatic events in practice, but it also stems from workplace violence. Often undetected and untreated, STS is at least a hidden correlate and perhaps a probable cause of myriad problems such as questionable practice with families, life-work conflicts, undesirable workforce turnover, and a sub-optimal organizational climate. Special interventions are needed. At the same time, new organizational designs are needed to promote and reinforce positive emotional labor. Arguably, positive emotional labor and the positive organizational climates it facilitates are requisites for harmonious relations between jobs and personal lives, desirable workforce retention, and better outcomes for children and families. What’s more, specialized interventions for positive emotional labor constitute a key component in the prevention system for STS. A dual design for positive emotional labor and STS (and other negative emotional labor) prevention/intervention is provided herewith. Early detection and rapid response systems for STS, with social work leadership, receive special attention. Guidelines for new organizational designs for emotional labor in child welfare are offered in conclusion.

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High tunnels are simple, plastic-covered, passive solar-heated structures in which crops are grown in the ground. They are used by fruit and vegetable growers to extend the growing season and intensify production in cold climates. The covered growing area creates a desert-like environment requiring carefully monitored irrigation practices. In contrast, the exterior expanse of a high tunnel generates a large volume of water with every measurable rainfall. Each 1,000 ft of high tunnel roof will generate approximately 300 gallons from a half inch of rain. Unless the high tunnel site is elevated from the surrounding area or drainage tiles installed, or other drainage accommodations are made around the perimeter, the soil along the inside edge of the high tunnel is nearly continuously saturated. High volumes of water can also create an erosion problem. The objective of this project was to design and construct a system that enables growers using high tunnels in their production operation to reduce drainage problems, erosion, and crop loss due to excess moisture in and around their high tunnel(s) without permanent environmental and soil mediations.

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The early Late Pliocene (3.6 to ~3.0 million years ago) is the last extended interval in Earth's history when atmospheric CO2 concentrations were comparable to today's and global climate was warmer. Yet a severe global glaciation during marine isotope stage (MIS) M2 interrupted this phase of global warmth ~3.30 million years ago, and is seen as a premature attempt of the climate system to establish an ice-age world. Our geochemical and palynological records from five marine sediment cores along a Caribbean to eastern North Atlantic transect show that increased Pacific-to-Atlantic flow via the Central American Seaway weakened the North Atlantic Current (NAC) and attendant northward heat transport prior to MIS M2. The consequent cooling of the northern high latitude oceans permitted expansion of the Greenland ice sheet during MIS M2, despite near-modern atmospheric CO2 concentrations. Before and after MIS M2, heat transport via the NAC was crucial in maintaining warm climates comparable to those predicted for the end of this century.

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Multiproxy paleoenvironmental records (pollen and planktonic isotope) from Ocean Drilling Program Site 976 (Alboran Sea) document rapid ocean and climate variations during the last glacial that follow the Dansgaard-Oeschger climate oscillations seen in the Greenland ice core records, thus suggesting a close link of the Mediterranean climate swings with North Atlantic climates. Continental conditions rapidly oscillated through cold-arid and warm-wet conditions in the course of stadial-interstadial climate jumps. At the time of Heinrich events, i.e., maximum meltwater flux to the North Atlantic, western Mediterranean marine microflora and microfauna show rapid cooling correlated with increasing continental dryness. Enhanced aridity conceivably points to prolonged wintertime stability of atmospheric high-pressure systems over the southwestern Mediterranean in conjunction with cooling of the North Atlantic.

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A novel laser microparticle detector used in conjunction with continuous sample melting has provided a more than 1500 m long record of particle concentration and size distribution of the NGRIP ice core, covering continuously the period approximately from 9.5-100 kyr before present; measurements were at 1.65 m depth resolution, corresponding to approximately 35-200 yr. Particle concentration increased by a factor of 100 in the Last Glacial Maximum (LGM) compared to the Preboreal, and sharp variations of concentration occurred synchronously with rapid changes in the delta18O temperature proxy. The lognormal mode µ of the volume distribution shows clear systematic variations with smaller modes during warmer climates and coarser modes during colder periods. We find µ ~ 1.7 µm diameter during LGM and µ ~ 1.3 µm during the Preboreal. On timescales below several 100 years µ and the particle concentration exhibit a certain degree of independence present especially during warm periods, when µ generally is more variable. Using highly simplifying considerations for atmospheric transport and deposition of particles we infer that (1) the observed changes of µ in the ice largely reflect changes in the size of airborne particles above the ice sheet and (2) changes of µ are indicative of changes in long range atmospheric transport time. From the observed size changes we estimate shorter transit times by roughly 25% during LGM compared to the Preboreal. The associated particle concentration increase from more efficient long range transport is estimated to less than one order of magnitude.

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Cretaceous to Quaternary sediments recovered at Leg 119 Sites 738 and 744 on the southern tip of the Kerguelen Plateau were studied in order to determine the depositional environment and the paleoceanography of the southern Indian Ocean and especially the long-term glacial history of East Antarctica. Emphasis is given to bulk-sediment composition, grain-size data, and clay mineralogy. The sediment sequence at the two sites is generally of a highly pelagic character, with nannofossil oozes, chalks, and limestones dominant from the Turanian to upper Miocene and diatom oozes dominant within the uppermost Miocene to Holocene interval. The first indication of glaciation at sea level is the occurrence of isolated gravel and terrigenous sand grains, which indicate ice rafting in the middle Eocene interval of 45.0-42.3 Ma. A major intensification of glaciation, probably the onset of continental East Antarctic glaciation, is recorded in sediments of early Oligocene age (36.0 Ma). All major sediment parameters document this event. The clay mineralogy changes from smectite-dominated assemblages, typical of moderately warm and humid climatic conditions in which chemical weathering processes are prevalent, to illite- and chlorite-dominated assemblages, indicative of cooler climates and physical weathering. Ice-rafted debris of both gravel and sand size occurs in large quantities in that interval and coincides with a change in the mode of carbonate deposition. Carbonate contents are relatively high and uniform (90%-95%) in strata younger than early Oligocene; in Oligocene to upper Miocene strata they fluctuate between 65% and 95%. Oligocene and Neogene hiatuses reflect an intensification of oceanic circulation and the increased erosional force of Circumpolar Deep Water. The long-term Cenozoic cooling trend was interrupted by a phase of early Miocene warming indicated by maximum Neogene smectite concentrations. Although ice-rafted debris is present only in minor amounts and mainly in the silt fraction of early Oligocene to late Miocene age, it shows that glaciers advanced to the East Antarctic shoreline throughout that time. Ice-rafting activity drastically increased in latest Miocene time, when carbonate deposition decreased and diatom ooze sedimentation started. This suggests a pronounced intensification of Antarctic glaciation combined with a northward migration of the Polar Front.