This paper proposes an improvement on the scattering-integral (SI) approach for acoustic frequency-domain full waveform inversion (FWI) based on the individual Born kernels. The main development is a method for calculating the steepest-descent direction and the pseudo-Newton direction by vector operations with definite physical meaning, without needing to store the huge Fr´echet kernels in mem…

Tahun Terbit

2009

We develop and validate a systematic approach to infer plate boundary strength and rheological parameters in models of mantle flow from surface velocity observations. Based on a realistic rheological model that includes yielding and strain rate weakening from dislocation creep, we formulate the inverse problem in a Bayesian inference framework. To study the distribution of parameters that are c…

For extensional wave propagation along a cylindrical pipe, there exists a natural stopband in the frequency range between the first and second modes. This study explores the feasibility and practicality of building a drill collar acoustic extensional-wave isolator by combining the stopbands of pipes of different thicknesses. Numerical modelling shows that this is indeed possible and a stopband …

The 14C-uptake method is the most common approach employed for estimating primary production in the ocean. Normalizing 14C-uptake to chlorophyll a and time yields a value termed the assimilation number, which is thought to reflect phytoplankton physiology. It is often assumed that the measured rate of 14C-uptake is between net and gross primary production, depending on the time scale of the inc…

It has been hypothesized that terrestrial particulate organic matter (t-POM) makes important contributions to Daphnia production in some lakes. We conducted a series of feeding experiments to explore the fatty acid responses in Daphnia to diets comprised of different terrestrial resources (i.e. Alnus rubra, Phragmites australis, Betula nana and Betula pendula) and mixed diets with terrestrial a…

This article first seeks to demonstrate the exceptional levels of protectionism accorded tothe agricultural sector, especially in many developed countries. It reviews the principal protectionist measures employed: domestic subsidies and price supports, production restrictions, and border measures; describes briefly the disciplines applicable to these measures under World Trade Organization law;…

Protistan grazers and viruses are major agents of mortality in marine microbial communities with substantially different implications for food-web dynamics, carbon cycling and diversity maintenance.While grazers and viruses are typically studied independently, their impacts on microbial communities may be complicated by direct and indirect interactions of their mortality effects. Using a modif…

We consider a diffuse interface approximation for the lipid phases of rotationally symmetric twophase bilayer membranes and rigorously derive its -limit. In particular,we prove that limit vesicles are C1 across interfaces, which justifies a regularity assumption that is widely made in formal asymptotic and numerical studies. Moreover, a limit membrane may consist of several topological spheres…

Haploid pluripotent stem cells, such as haploid embryonic stem cells (haESCs), facilitate the genetic study of recessive traits. In vitro, fish haESCs maintain haploidy in both undifferentiated and differentiated states, but whether mammalian haESCs can preserve pluripotency in the haploid state has not been tested. Here,wereport that mouse haESCs can differentiate in vitro into haploid epibla…