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991.
An inexpensive improvement to lightweight percussion coring systems is presented. Non-stretching lines are often required to facilitate core sampling in hundreds of metres of water, unfortunately such lines are usually negatively buoyant, which creates difficulties in keeping lightweight core assemblies upright while lowering through the water column. The addition of urethane closed-cell foam to the core head creates buoyancy that vertically stabilizes the coring assembly within the water column and prevents the core barrel from contacting the sediment-water interface non-vertically.  相似文献   
992.
The object of the paper is to provide an insight into the changes in livelihood strategies of the people in the Garhwal Himalayas over time. From sustaining an economy based on transit trade and subsistence agriculture, there has been a shift towards tourism in recent times. This shift has been due to the tradition of pilgrimage to the higher reaches and also due to promotion by the state by developing infrastructure and providing incentives. The paper is divided into four parts. In the first part, the policies of the colonial state and the events leading to the destruction of forests and the impoverishment of the self-sustaining semi-pastoral economy in the Garhwal Himalayas are outlined. It is argued that the destruction of forests and subsequently, the economy of the Himalayas were directly responsible for the large-scale migration to the plains. This also led to further exploitation of forests by the people who were unfamiliar with any other form of livelihood. The paper also discusses the policies of the newly independent Indian state and sees them as an extension of the British policy of large-scale exploitation of Himalayan forests for the purpose of development and economic growth. In the third section, the growth of ecotourism as a direct outcome of the orocess of deforestation and as resulting from the need of society to conserve and yet to earn a livelihood is discussed. The case study of the Gangotrir egion examines the dilemma faced by the people of Garhwal in sustaining their livelihood, income or the development in the area. In addition, tourism has fostered monopolies of groups external to the region thereby contributing neither to the income or the development in the area. In addition, there is an added threat to the environment-deforestation, and erosion-a direct outcome of increased and unplanned tourism. Such problems demand state intervention and management of t.ourism. The conclusion to the paper asserts that in order that the requirements of the society to progress and to sustain itself in its natural habitat are not compromised, it is essential to increase the process of democratization by strengthening local structures and by vesting the community with the autonomy to determine its future. The paper therefore argues that ecotourism in the Himalayas undertaken without local involvement is not desirable. The constant need for local monitoring of external agencies or even of the State‘s participation and the need for re-evaluation of environmental standards are cumbersome details that add to the costs of promoting low-impact tourism. To be viable, ecotourism should be community based and the needs of the community, their ideas of conservation should be given prime importance and local community must be encouraged to review the standards governing conservation. Local structures should thus receive patronage and promotion, so that ecotourism becomes a dynamic facet of economic development.  相似文献   
993.
Ninety-eight clay mineral samples from the YSDP102 core were analyzed by x-ray diffractometer to study the four clay minerals: illite, chlorite, kaolinite and smectite. Twenty-eight samples had been analyzed on the laser particle-siz eanalyzer to reveal the particle features of the sediments. Distribution of the clay minerals and the particle characteristics in the YSDP102 core show that the core experienced three different depositional periods and formed three different sedimentary intervals due to different sediment sources and different depositional environments. Features of the clay minerals and the heavy minerals in the YSDP102 core indicate that coarse-grained sediments and fine-grained sediments result from different sources. The Yellow Sea Warm Current has greatly influenced the sedimentary framework of this region since the current‘s formation.  相似文献   
994.
1 Introduction InChina ,coastalcitiesaremostlyregionaleconomicdevelopmentcenters.Becauseoftheirspecialgeogra phiclocations ,typhoonsandassociatedstormsurgescauseheavylossesoflivesandproperties.In 1 992 Qing daowasfloodedduetothecoincidenceoftheastrono m…  相似文献   
995.
996.
The Hubble constant is split into two terms H = H1 + H2 , where H1 is a decreasing function due to the Big Bang and the subsequent gravitational interaction that slows the expansion of the Universe and H2 is an increasing function that corresponds to dark energy which accelerates this expansion. For T = 13.7 Gyr we prove that H2(T) > 5 m/(yr AU). This is a quite large number and thus the impact of dark energy, which is spread almost everywhere uniformly, should be observable not only on large scales, but also in our Solar system. In particular, we show that Earth, Mars and other planets were closer to the Sun 4.5 Gyr ago. The recession speed ≈5.3 m/yr of the Earth from the Sun seems to be just right for an almost constant influx of solar energy from the origin of life on Earth up to the present over which time the Sun’s luminosity has increased approximately linearly. This presents further support for the Anthropic Principle. Namely, the existence of dark energy guarantees very stable conditions for the development of intelligent life on Earth over a period of 3.5 Gyr.  相似文献   
997.
We present photometric observations of two post-common-envelope stars, NY Vir (=PG 1336-018) and HS 0705 + 6700. The V band CCD observation of NY Vir was performed by a 40 cm telescope at Ege University Observatory and the R band observations of HS 0705 + 6700 were performed by 100 cm telescope at TÜB?TAK National Observatory. The new light curves were analyzed by the WD code and the physical parameters of stars were determined. We obtained new mid-eclipse timings for HS 0705 + 6700 and combined them with those previously published data. The analysis of the O-C residuals yields a period of about 8.06 ± 0.28 yr and an amplitude of 98.5 s for the system HS 0705 + 6700, which is attributed to the third star physically bounded to the evolved eclipsing pair. A mass function of 1.2 × 10−4 M for the third star is obtained. The existence of a third star is also confirmed by the light curve analysis, indicating light contribution of about 0.043 at phase 0.25 in R-bandpass of the eclipsing pair. Using mass-luminosity relationship of the low mass stars we estimate a mass of 0.12 M with an orbital inclination of about 20°. The O-C residuals obtained for the system NY Vir were represented by a downward parabola which indicates orbital period decrease in the system. Using the coefficient of quadratic term we calculate a rate of orbital period decrease of about dP/dt = −4.09 × 10−8days yr−1. The period decrease we have measured in NY Vir may be explained by angular momentum loss from the binary system.  相似文献   
998.
999.
We model the thermal evolution of a subsurface ocean of aqueous ammonium sulfate inside Titan using a parameterized convection scheme. The cooling and crystallization of such an ocean depends on its heat flux balance, and is governed by the pressure-dependent melting temperatures at the top and bottom of the ocean. Using recent observations and previous experimental data, we present a nominal model which predicts the thickness of the ocean throughout the evolution of Titan; after 4.5 Ga we expect an aqueous ammonium sulfate ocean 56 km thick, overlain by a thick (176 km) heterogeneous crust of methane clathrate, ice I and ammonium sulfate. Underplating of the crust by ice I will give rise to compositional diapirs that are capable of rising through the crust and providing a mechanism for cryovolcanism at the surface. We have conducted a parameter space survey to account for possible variations in the nominal model, and find that for a wide range of plausible conditions, an ocean of aqueous ammonium sulfate can survive to the present day, which is consistent with the recent observations of Titan's spin state from Cassini radar data [Lorenz, R.D., Stiles, B.W., Kirk, R.L., Allison, M.D., del Marmo, P.P., Iess, L., Lunine, J.I., Ostro, S.J., Hensley, S., 2008. Science 319, 1649-1651].  相似文献   
1000.
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