论塔吉克斯坦杜尚别——瓦赫什地区地震活动性的地质标志问题

据航、卫片解译、杜尚别－瓦赫什地区有１１条线性结构。由它们构成的努涅克和科摩索姆洛巴德构造结为晚更新世一全新世活动构造，未来可能发生强震及灾难性地震。     

Data-driven Simulations of Magnetic Field Evolution in Active Region 11429:Magneto-frictional Method Using PENCIL CODE

Coronal magnetic fields evolve quasi-statically over long timescales and dynamically over short timescales.As of now there exist no regular measurements of coronal magnetic fields,and therefore generating the coronal magnetic field evolution using observations of the magnetic field at the photosphere is a fundamental requirement to understanding the origin of transient phenomena from solar active regions(ARs).Using the magneto-friction(MF)approach,we aim to simulate the coronal field evolution i...     

In the other 90%: phytoplankton responses to enhanced nutrient availability in the Great Barrier Reef Lagoon

Our view of how water quality effects ecosystems of the Great Barrier Reef (GBR) is largely framed by observed or expected responses of large benthic organisms (corals, algae, seagrasses) to enhanced levels of dissolved nutrients, sediments and other pollutants in reef waters. In the case of nutrients, however, benthic organisms and communities are largely responding to materials which have cycled through and been transformed by pelagic communities dominated by micro-algae (phytoplankton), protozoa, flagellates and bacteria. Because GBR waters are characterised by high ambient light intensities and water temperatures, inputs of nutrients from both internal and external sources are rapidly taken up and converted to organic matter in inter-reefal waters. Phytoplankton growth, pelagic grazing and remineralisation rates are very rapid. Dominant phytoplankton species in GBR waters have in situ growth rates which range from approximately 1 to several doublings per day. To a first approximation, phytoplankton communities and their constituent nutrient content turn over on a daily basis. Relative abundances of dissolved nutrient species strongly indicate N limitation of new biomass formation. Direct ((15)N) and indirect ((14)C) estimates of N demand by phytoplankton indicate dissolved inorganic N pools have turnover times on the order of hours to days. Turnover times for inorganic phosphorus in the water column range from hours to weeks. Because of the rapid assimilation of nutrients by plankton communities, biological responses in benthic communities to changed water quality are more likely driven (at several ecological levels) by organic matter derived from pelagic primary production than by dissolved nutrient stocks alone.     

The grain-size characteristics of Quaternary deposits at Xingshan near Siping in Jilin province, China

This research paper analyses the grain-size characteristics of the Quaternary deposits at Xingshan near Siping, Jilin province in China by employing graphic measures to study the grain size distribution and its mode of transport and deposition. The Quaternary deposits at Xingshan lie unconformable on Cretaceous rocks made of siltstone, mudstone and sandstone. The average grain size is between 8.06 to 8.55Ф （0. 002 6 0. 003 7 mm）. The Quaternary deposits at Xingshan mainly compose of very fine silt to clay. The compositions of the grade are clay 63 % and silt 37 %. The clay size components are weathered debris transported and deposited by flowing water from the SE highlands or hills to the low lying NW Xingshan plains whereas the silty components accumulated by aoelian process. The Quaternary deposits at Xingshan accumulated in the middle and late Pleistocene interglacial periods from （459.12 - 39.03 ） ka to （88.92 - 7.56 ） ka. The standard deviation ranged from 0.96 to 1.36%, indicating that the sediments are moderately to poorly sorted, Coefficient of skewness ranged from 0.16 - 0.31 with an average skewness of 0. 218, （Positively skewed towards fine）. Kurtosis values （0.84- 1.05） from the grain size distribution and visual inspection of the frequency curves indicate platykurtic to mesokurtic curves and unimodal to bimodal grain-size distribution. The type of deposit formation is sand dune and the source is at a distal from its provenance.     

Mushroom production as an alternative for rural development in a forested mountainous area

Wild mushrooms are recognized as important non-wood forest products in mountainous ecosystems, but their real potential for generating rural economies has not been fully evaluated due to the difficulties in obtaining reliable productivity data, minimizing their true potential as contributor to rural economies. Mushroom yield models based on large data series from Pinus forest ecosystems in the region of Catalonia(Spain), combined with data from the Spanish National Forest Inventory allow us to estimate the potential mushroom productivity by forest ecosystems. The results of 24,500 tons/yr of mushrooms of which 16,300 tons are classified as edible and 7,900 tons are commonly marketed demonstrate the importance of mushroom productions in Catalonian pine forests, mostly located in mountainous areas where the development of agricultural activities is limited. Economic mushroom value is estimated at 48 million € for the edible mushroom and 32 million € for those corresponding to marketable yields, confirming the potential of this non-wood forest product. These production results and corresponding economic values provide a basis for the incorporation of wild mushrooms as significant non-wood forest products in the development of forest policies in mountainous areas.     

Fresh snow chemistry from high mountain regions in central himalayas

Investigations of atmospheric composition in the Himalayas has been limited in both temporal and spatial scales, mainly due to difficult logistics. Ideal sites for monitoring atmospheric composition and its evolution should be free from local pollution and representative of the remote troposphere (HUEBERT et al., 1980). As the Himalayas are far removed from highly industrialized regions they provide suitable locations to monitor the chemistry of the remote troposphere and to study the evolu…     

A Measurement of Omega from the North American Test Flight of Boomerang

We use the angular power spectrum of the cosmic microwave background, measured during the North American test flight of the Boomerang experiment, to constrain the geometry of the universe. Within the class of cold dark matter models, we find that the overall fractional energy density of the universe Omega is constrained to be 0.85相似文献   

Comparison of Transient Network Brightenings and Explosive Events in the Solar Transition Region

I analyze the properties of the pulsed emission from the accreting millisecond pulsar SAX J1808.4-3658 in observations of its 1998 April outburst by the Rossi X-Ray Timing Explorer. Pulse phase spectroscopy shows that the emission evolves from a hard spectrum (power law with photon index of 2.39+/-0.06) to a soft spectrum (index of 3.39+/-0.24). This softening is also observable as a phase lag in the fundamental of low-energy photons with respect to high-energy photons. I show that this lag is roughly constant over 10 days of the outburst. I fit these data with a model in which the pulse emission is from a hot spot on the rotating neutron star and the flux as a function of phase is determined in a calculation which includes the effects of general relativity. The energy-dependent lags are very well described by this model. The harder spectra at earlier phases (i.e., as the spot approaches) are the result of larger Doppler-boosting factors that are important for this fast pulsar. Since this model is sensitive to the equatorial speed as an independent parameter and since the spin frequency is known, this offers us a new means of measuring the neutron star radius, which is notoriously difficult to determine.     

Runaway of Line-driven Winds toward Critical and Overloaded Solutions

Line-driven winds from hot stars and accretion disks are thought to follow a unique, critical solution that corresponds to a maximum mass-loss rate and a particular velocity law. We show that in the presence of negative velocity gradients, radiative-acoustic (Abbott) waves can drive shallow wind solutions toward larger velocities and mass-loss rates. Perturbations that are introduced downstream from the critical point of the wind lead to a convergence toward the critical solution. By contrast, low-lying perturbations cause evolution toward a mass-overloaded solution, developing a broad deceleration region in the wind. Such a wind differs fundamentally from the critical solution. For sufficiently deep-seated perturbations, overloaded solutions become time-dependent and develop shocks and shells.