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11.
Photoelectric observations on five consecutive nights yield a period of rotation of 80 ± 2 hr with an amplitude of 0.7 magnitude for 182 Elsa, making it the longest period of rotation known to date. 182 Elsa is classed as an S object with a diameter of 48 km. 相似文献
12.
A crystal-chemical classification of borate structures with emphasis on hydrated borates 总被引:1,自引:0,他引:1
The rules governing formation of hydrated borate polyanions that were proposed by C.L. Christ in 1960 are critically reviewed and new rules added on the basis of recent crystal structure determinations. Principles and classifications previously published by others are also critically reviewed briefly. The fundamental building blocks from which borate polyanions can be constructed are defined on the basis of the number n of boron atoms, and the fully hydrated polyanions are illustrated. Known structures are grouped accordingly, and a shorthand notation using n and symbols Δ = triangle, T = tetrahedron is introduced so that the polyanions can be easily characterized. For example, 3:Δ+2T describes [B3O3(OH)5]2?. Correct structural formulas are assigned borates with known structures whereas borates of unknown structure are grouped separately. 相似文献
13.
The clonal growth of 9 seagrass species was modeled using a simulation model based on observed clonal growth rules (i.e.,
spacer length, rhizome elongation rates, branching rates, branching angle) and shoot mortality rates for seagrass species.
The results of the model confirmed the occurrence of complex, nonlinear growth of seagrass clones derived from internal dynamics
of space occupation. The modeled clones progressed from a diffuse-limited aggregation (DLA), dendritic growth, identified
with a guerrilla strategy of space occupation, to a compact (Eden) growth, comparable to the phalanx strategy of space occupation,
once internal recolonization of gaps, left by dead shoots within the clone, begins. The time at which seagrass clones shifted
from diffuse limited to compact growth was predictable from the branching angle and frequency of the species and varied from
1 yr to several decades among species. As a consequence the growth behavior and the apparent growth strategy of the species
changes with the development of the clones. The results of the model demonstrate that the emergent complexity of seagrass
clonal growth is contained within the simple set of growth rules that can be used to represent clonal growth. 相似文献
14.
A structural transect in the Lower Dolpo highlights that the deformation and metamorphism of the Tibetan Zone (TZ) increase toward the bottom of the sequence. The contact with the underlying HHC is marked by a metamorphic jump from amphibolite facies in the carbonatic rocks of the upper part of the HHC to greenschist facies marbles in the TZ. Moreover, the HHC and the TZ show different metamorphic histories. The contact zone shows a strain increase accompanied by asymmetric folds with a top-to-the-northeast vergence, connected to a down-to-the-northeast tectonic transport. The contact is interpreted as an extensional shear zone, connected to the South Tibetan Detachment System. To cite this article: R. Carosi et al., C. R. Geoscience 334 (2002) 933–940. 相似文献
15.
J.-F. Miao L. J. M. Kroon J. Vilà-Guerau de Arellano A. A. M. Holtslag 《Meteorology and Atmospheric Physics》2003,84(3-4):157-170
Summary A three-dimensional non-hydrostatic atmospheric model RAMS, version3b, is used to examine the impact of complex topography on the sea breeze under heterogeneous and degradation land use characteristics. In the study, it is shown that topography plays an important role in the sea-breeze circulation by aligning the sea breeze front to the coastline and locating the convergence zones close to the mountain range. When the sea breeze is coupled with the upslope wind, the sea-breeze circulation is strengthened by the topography.Sensitivity analyses are carried out to determine the influence of vegetation and soil moisture, i.e., land surface modifications, to this thermally driven flow. Land degradation results in an enhanced sea-breeze circulation which is characterized by a stronger onshore flow, a stronger return current, a larger updraft velocity associated with the sea-breeze front and further inland penetration. Other important features are a deeper sea-breeze depth, a larger downdraft velocity behind the sea-breeze front, and a longer offshore extent. The results also show how land changes modify the sea breeze temporal evolution resulting in an earlier onset and later end. The study stresses the convenience of using three-dimensional models with detailed land surface information to model the sea breeze in complex terrain where land use is rapidly modified.Received February 25, 2002; accepted October 7, 2002
Published online April 10, 2003 相似文献
16.
Errikarta-Imanol Yll Ramon Perez-Obiol Jose Pantaleon-Cano Joan Maria Roure 《Quaternary Research》1997,48(3):339-347
Four pollen diagrams from Minorca (Balearic Islands) have been correlated with other previously studied sequences from Majorca and Minorca to define a Holocene landscape sequence for the region from 8000 yr B.P. to the present. The lower part of the pollen diagrams reflects a climatic phase with more rain and less-marked seasonality than today. Significant quantities ofCorylus, Buxus,and mesophilous taxa are found. In the middle part, between 5000 and 4000 yr B.P., a strong change is recorded in composition and structure of the vegetational landscape, with vegetation appearing that was adapted to Mediterranean conditions. This episode coincided with the first human colonization of the island and also with a widespread climatic change in the western Mediterranean region. The change in taxa was complex and some sclerophyllous taxa suchOleaplayed an important role in the transformation of the landscape physiognomy from the mid-Holocene until the present. Although human activities have removed much of the Mediterranean vegetation on the Balearic Islands, it seems clear that the changes have been brought about, in part, by increasing dryness. 相似文献
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