Geostatistics Wollongong '96: Volumes 1 and 2 By E. Y. Baafi and N. A. Schofield (eds.)     

James Russell Carr 《Mathematical Geology》1999,31(6):743-744

  相似文献   

A spatial econometric panel data examination of endogenous versus exogenous interaction in Chinese province-level patenting   总被引：2，自引：1，他引：2  

James P. LeSage  Yuxue Sheng 《Journal of Geographical Systems》2014,16(3):233-262

We examine the provincial-level relationship between domestic Chinese intellectual property (IP) and knowledge stocks using a space–time panel model and data set covering monthly patent activity over the period 2002–2010. The goal of the modeling exercise is to explore the elasticity response of IP to knowledge stocks classified by type of creator (universities and research institutes, enterprises, and individuals). A focus is on spatial and time dependence in the relationship between knowledge stocks and IP, which implies spatial spillovers and diffusion over time. Many past studies of regional knowledge production have focused on patent applications as a proxy for regional output from the knowledge production process. However, this ignores the distinction between patent applications and patents granted, with the latter reflecting a decision and ability to convert knowledge produced into IP. This study differs in its focus on the regional relation between IP and knowledge stocks and the space–time dynamics of these. Using patents granted as a proxy for IP, and past patent applications as a proxy for regional knowledge stocks, allows us to explore the implied quality of knowledge production by various types of creators. Because Chinese patent applications have grown by 22 %, questions have been raised about the quantity versus quality of these applications. Our findings shed light on this issue.  相似文献   

Flood tide circulation near beaufort inlet, North Carolina: Implications for larval recruitment     

James H. Churchill  James L. Hench  Richard A. Luettich  Jackson O. Blanton  Francisco E. Werner 《Estuaries and Coasts》1999,22(4):1057-1070

Drifter tracks and shipboard CTD observations have revealed a number of distinct features of the flood tide circulation carrying water through Beaufort Inlet, North Carolina. One of the most noteworthy of these features is a nearshore jet in the flow carrying water to the inlet on a flood tide. Characterized by a shoreward increase in longshore flow, the jet produces a narrow coastal zone over which water is carried into the inlet. The jet appears to be principally a tidal phenomenon, as it is closely reproduced by a tidally-driven barotropic numerical model. The model results also indicate the jet may be a near-inlet feature. Model simulations of spring tide conditions show the jet confined to within 4 km of the inlet mouth. Another observed phenomenon, which is reproduced by the tidal model, is a distinct splitting of the flow entering the inlet, in which water passing through a particular inlet segment tends to move up-estuary along a well-defined path. An observed flow feature not reproduced by the tidal model is an eastward skew of the region over which water is drawn into the inlet on a flood tide. This asymmetry is unrelated to the local wind. Modeling results from a previous study suggest it may be due to convergent flow at the edge of the low salinity plume issuing from the inlet. Taken together, the results of this and other recent studies in the Beaufort Inlet region reveal the importance of nearshore currents on the eastern side of the inlet in delivering oceanic-spawned larvae to the estuarine system connected to the inlet.  相似文献   

Adaptations for scavenging by three diverse bathyla species, Eptatretus stouti, Neptunea amianta and Orchomene obtusus     

Mario N Tamburri  James P Barry 《Deep Sea Research Part I: Oceanographic Research Papers》1999,46(12):47

Many deep-sea animals derive part of their nutrition from rare and unpredictable food falls. However, traits that allow organisms inhabiting the sea floor to exploit carrion are poorly understood. We found in laboratory experiments that hagfish (Eptatretus stouti), gastropods (Neptunea amianta) and amphipods (Orchomene obtusus) survived extended periods of starvation, in some cases for more than a year. When exposed to odors emitted from carrion, most individuals of E. stouti and O. obtusus began searching for food within seconds, whereas none responded to the scent of the live prey. In contrast, the slow crawling N. amianta readily consumed carrion but showed no apparent response to any odor solutions tested. Because more motile animals exhibited lower thresholds for response to signal molecules, sensitivity to chemical cues appears related to species mobility. Hagfish were also found to defend carrion from some competitors by releasing slime when feeding. Though varying dramatically in size, morphology, locomotive ability, and phylogeny, these three species all possess traits well suited for a scavenging lifestyle.  相似文献   

The Optimal Design of TMD for Offshore Structures   总被引：15，自引：0，他引：15  

Sau Lon James HU  Tomotsuka TAKAYAMA 《中国海洋工程》1999,(2)

This paper presents the optimal design procedure of Tuned Mass Damper(TMD)for re-ducing vibration of an actual steel jacket offshore platform excited by random wave loading.In this study,a frequency domain is taken.The force on the structure is determined by use of the linearized Morisonequation for an input Power Spectral Density(PSD)of wave elevation.The sensitivity of optimum valuesof TMD to characteristic parameters of random wave spectrum is analyzed.An optimized TMD designfor the modeled platform is given based on design conditions and the findings of the study.  相似文献   

Premature dismissal of high-redshift elliptical galaxies     

Raul Jimenez  Amancio C. S. Friaça  James S. Dunlop  Roberto J. Terlevich  John A. Peacock  Louisa A. Nolan 《Monthly notices of the Royal Astronomical Society》1999,305(1):L16-L20

  相似文献   

Cosmic-ray positrons: are there primary sources?     

Stphane Coutu  Steven W. Barwick  James J. Beatty  Amit Bhattacharyya  Chuck R. Bower  Christopher J. Chaput  Georgia A. de Nolfo  Michael A. DuVernois  Allan Labrador  Shawn P. McKee  Dietrich Müller  James A. Musser  Scott L. Nutter  Eric Schneider  Simon P. Swordy  Gregory Tarl  Andrew D. Tomasch  Eric Torbet 《Astroparticle Physics》1999,11(4):208-435

Galactic cosmic rays consist of primary and secondary particles. Primary cosmic rays are thought to be energized by first order Fermi acceleration processes at supernova shock fronts within our Galaxy. The cosmic rays that eventually reach the Earth from this source are mainly protons and atomic nuclei, but also include electrons. Secondary cosmic rays are created in collisions of primary particles with the diffuse interstellar gas. They are relatively rare but carry important information on the Galactic propagation of the primary particles. The secondary component includes a small fraction of antimatter particles, positrons and antiprotons. In addition, positrons and antiprotons may also come from unusual sources and possibly provide insight into new physics. For instance, the annihilation of heavy supersymmetric dark matter particles within the Galactic halo could lead to positrons or antiprotons with distinctive energy signatures. With the High-Energy Antimatter Telescope (HEAT) balloon-borne instrument, we have measured the abundances of positrons and electrons at energies between 1 and 50 GeV. The data suggest that indeed a small additional antimatter component may be present that cannot be explained by a purely secondary production mechanism. Here we describe the signature of the effect and discuss its possible origin.  相似文献   

Warps and cosmic infall   总被引：1，自引：0，他引：1  

Ing-Guey Jiang  James Binney 《Monthly notices of the Royal Astronomical Society》1999,303(1):L7-L10

  相似文献   

Hydrodynamical non-radiative accretion flows in two dimensions     

James M. Stone  James E. Pringle †  Mitchell C. Begelman ‡ 《Monthly notices of the Royal Astronomical Society》1999,310(4):1002-1016

Two-dimensional (axially symmetric) numerical hydrodynamical calculations of accretion flows that cannot cool through emission of radiation are presented. The calculations begin from an equilibrium configuration consisting of a thick torus with constant specific angular momentum. Accretion is induced by the addition of a small anomalous azimuthal shear stress which is characterized by a function ν . We study the flows generated as the amplitude and form of ν are varied. A spherical polar grid which spans more than two orders of magnitude in radius is used to resolve the flow over a wide range of spatial scales. We find that convection in the inner regions produces significant outward mass motions that carry away both the energy liberated by and a large fraction of the mass participating in the accretion flow. Although the instantaneous structure of the flow is complex and dominated by convective eddies, long-time averages of the dynamical variables show remarkable correspondence to certain steady-state solutions. The two-dimensional structure of the time-averaged flow is marginally stable to the Høiland criterion, indicating that convection is efficient. Near the equatorial plane, the radial profiles of the time-averaged variables are power laws with an index that depends on the radial scaling of the shear stress. A stress in which ν ∝ r ^1/2 recovers the widely studied self-similar solution corresponding to an ' α -disc'. We find that, regardless of the adiabatic index of the gas, or the form or magnitude of the shear stress, the mass inflow rate is a strongly increasing function of radius, and is everywhere nearly exactly balanced by mass outflow. The net mass accretion rate through the disc is only a fraction of the rate at which mass is supplied to the inflow at large radii, and is given by the local, viscous accretion rate associated with the flow properties near the central object.  相似文献   

Line-driven disc wind models with an improved line force     

Daniel Proga  †  James M. Stone  Janet E. Drew 《Monthly notices of the Royal Astronomical Society》1999,310(2):476-482

We describe an efficient method of calculating the radiation pressure resulting from spectral lines, including all the terms in the velocity gradient tensor. We apply this method to calculate the two-dimensional, time-dependent structure of winds from luminous discs. Qualitative features of our new models are very similar to those we calculated including only the dominant terms in the tensor. In particular, we find that models which displayed unsteady behaviour in our earlier paper are also unsteady with the new method, and gross properties of the winds, such as mass-loss rate and characteristic velocity, are not changed by the more accurate approach. The largest change caused by the new method is in the disc-wind opening angle: winds driven only by the disc radiation are more polar with the new method, whilst winds driven by the disc and central object radiation are typically more equatorial. In the closing discussion, we provide further insight into the way the geometry of the radiation field and consequent flow determine the time properties of the flow.  相似文献