944 resultados para Northern Central Railway Company.
Resumo:
Analyses of pollen, macrofossils and microscopic charcoal in the sediment of a small sub-alpine lake (Karakol, Kyrgyzstan) provide new data to reconstruct the vegetation history of the Kungey Alatau spruce forest during the late-Holocene, i.e. the past 4,000 years. The pollen data suggest that Picea schrenkiana F. and M. was the dominant tree in this region from the beginning of the record. The pollen record of pronounced die-backs of the forests, along with lithostratigraphical evidence, points to possible climatic cooling (and/or drying) around 3,800 cal year B.P., and between 3,350 and 2,520 cal year B.P., with a culmination at 2,800-2,600 cal B.P., although stable climatic conditions are reported for this region for the past 3,000-4,000 years in previous studies. From 2,500 to 190 cal year B.P. high pollen values of P. schrenkiana suggest rather closed and dense forests under the environmental conditions of that time. A marked decline in spruce forests occurred with the onset of modern human activities in the region from 190 cal year B.P. These results show that the present forests are anthropogenically reduced and represent only about half of their potential natural extent. As P. schrenkiana is a species endemic to the western Tien Shan, it is most likely that its refugium was confined to this region. However, our palaeoecological record is too recent to address this hypothesis thoroughly.
Resumo:
The status and dynamics of glaciers are crucial for agriculture in semiarid parts of Central Asia, since river flow is characterized by major runoff in spring and summer, supplied by glacier- and snowmelt. Ideally, this coincides with the critical period of water demand for irrigation. The present study shows a clear trend in glacier retreat between 1963 and 2000 in the Sokoluk watershed, a catchment of the Northern Tien Shan mountain range in Kyrgyzstan. The overall area loss of 28% observed for the period 1963–2000, and a clear acceleration of wastage since the 1980s, correlate with the results of previous studies in other regions of the Tien Shan as well as the Alps. In particular, glaciers smaller than 0.5 km2 have exhibited this phenomenon most starkly. While they registered a medium decrease of only 9.1% for 1963–1986, they lost 41.5% of their surface area between 1986 and 2000. Furthermore, a general increase in the minimum glacier elevation of 78 m has been observed over the last three decades. This corresponds to about one-third of the entire retreat of the minimum glacier elevation in the Northern Tien Shan since the Little Ice Age maximum.
Resumo:
Stable-water-isotope data (deltaD and delta(18)O) from three groups of samples (fresh-snow and snow-pit samples collected on Qomolangma (Mount Everest) and Xixabangma during field seasons 1997,1998 and 2001, and precipitation samples collected at Tingri station during summer 2000) are presented and used to survey the isotopic composition of precipitation over the northern slope of the central Himalaya. Multi-year snow-pit samples on Qomolangma have a local meteoric water-line (slope = 8) close to the global value. Deuterium excess (d = deltaD - 8delta(18)O) values at Tingri are much lower than those in fresh snow from Qomolangma, probably due to differences in moisture source and air-mass trajectories as well as local weather conditions. There is no obvious seasonal trend for d values in the Qomolangma region. A negative relationship exists between delta(18)O and d values in both fresh snow on Qomolangma and precipitation at Tingri. Fresh-snow samples collected from different altitudes on Xixabangma allow us to investigate the altitude effect on delta(18)O values in snow. Of four storm events, only one has an obvious altitude effect on delta(18)O variation and a very low gradient of -0.1% per 100 in elevation.
Resumo:
Climatic relationships were established in two 210Pb dated pollen sequences from small mires closely surrounded by forest just below actual forest limits (but about 300 m below potential climatic forest limits) in the northern Swiss Alps (suboceanic in climate; mainly with Picea) and the central Swiss Alps (subcontinental; mainly Pinus cembra and Larix) at annual or near-annual resolution from ad 1901 to 1996. Effects of vegetational succession were removed by splitting the time series into early and late periods and by linear detrending. Both pollen concentrations detrended by the depth-age model and modified percentages (in which counts of dominant pollen types are down-weighted) are correlated by simple linear regression with smoothed climatic parameters with one-and two-year timelags, including average monthly and April/September daylight air temperatures and with seasonal and annual precipitation sums. Results from detrended pollen concentrations suggest that peat accumulation is favoured in the northern-Alpine mire either by early snowmelt or by summer precipitation, but in the central-Alpine mire by increased precipitation and cooler summers, suggesting a position of the northern-Alpine mire near the upper altitudinal limit of peat formation, but of the central-Alpine mire near the lower limit. Results from modified pollen percentages indicate that pollen pro duction by plants growing near their upper altitudinal limit is limited by insufficient warmth in summer, and pollen production by plants growing near their lower altitudinal limit is limited by too-high temperatures. Only weakly significant pollen/climate relationships were found for Pinus cembra and Larix, probably because they experience little climatic stress growing 300 m below the potential climatic forest limit.
Heat flow in the Central Basin of the Indian Ocean and the northern part of the Afanasy Nikitin Rise
Resumo:
Heat flux data obtained during Cruise 20 of R/V Akademik Mstislav Keldysh in the Central Basin of the Indian Ocean and northern part of the Afanasy Nikitin Rise are presented. Thermal conditions on the rise are not associated with an anomalous zone of the large tectonic deformation block north of it. Geothermal data indicate that the Afanasy Nikitin Rise has formed near an ancient spreading axis. Distribution of measured heat flux values indicates an additional source of heat in the Central Basin resulting from dissipative heating of the crust in the two-stage plate tectonics model.
Resumo:
Changes in land use and land cover throughout the eastern half of North America have caused substantial declines in populations of birds that rely on grassland and shrubland vegetation types, including socially and economically important game birds such as the Northern Bobwhite (Colinus virginianus; hereafter bobwhites). As much attention is focused on habitat management and restoration for bobwhites, they may act as an umbrella species for other bird species with similar habitat requirements. We quantified the relationship of bobwhites to the overall bird community and evaluated the potential for bobwhites to act as an umbrella species for grassland and shrubland birds. We monitored bobwhite presence and bird community composition within 31 sample units on selected private lands in the south-central United States from 2009 to 2011. Bobwhites were strongly associated with other grassland and shrubland birds and were a significant positive predictor for 9 species. Seven of these, including Bell's Vireo (Vireo bellii), Dicksissel (Spiza americana), and Grasshopper Sparrow (Ammodramus savannarum), are listed as species of conservation concern. Species richness and occupancy probability of grassland and shrubland birds were higher relative to the overall bird community in sample units occupied by bobwhites. Our results show that bobwhites can act as an umbrella species for grassland and shrubland birds, although the specific species in any given situation will depend on region and management objectives. These results suggest that efficiency in conservation funding can be increased by using public interest in popular game species to leverage resources to meet multiple conservation objectives.
Resumo:
En el campo del ferrocarril es necesaria tecnología avanzada que ayude en la seguridad de los trenes y de los pasajeros, en caso de viajes comerciales. Para ello en los pasos a nivel es necesario tener mecanismos que detallen cualquier incidencia, o cualquier anomalía respecto a las vías, bajadas de vayas, etc. Aquí toma vida esta aplicación llamada SCSE (Sistema Supervisor Central de Eventos en Entorno Ferroviario), que ofrece una cantidad importante de información. Esta aplicación recoge en el momento toda la información de los distintos pasos a nivel; y nos dice dónde está fallando el paso, si hay un error en la subida/bajada de vayas, si el semáforo no ha cambiado de color a tiempo... y lo hace visual en la pantalla. Con esta aplicación se pretende ofrecer una mayor eficacia en seguridad, una mayor rapidez en reparación de incidencias y una organización dentro de la empresa para poder ver sobre que se está trabajando.---ABSTRACT---In the field of rail technology is needed to assist in the safety of trains and passengers in case of commercial travel. To do this on level crossings is necessary to have mechanisms that detail any incident or any matter relating to rails etc. Here comes alive this application called SCSE (Central Events Supervisor System Environment Railway), which provides a significant amount of information. This application collects in the moment all the information of the different level crossings; and it tells us where it is failing level crossing, if there is an error in the up / down, if the light has not changed color in time ... and makes visual on the screen. With this application is intended to provide more effective security, a faster repair incidents and organization inside the company to see on which they are working.