An Analytic Simplification for the Reconstruction Problem of Electrical Impedance Tomography

This paper introduces a new reconstruction algorithm for electrical impedance tomography. The algorithm assumes that there are two separate regions of conductivity. These regions are represented as eccentric circles. This new algorithm then solves for the location of the eccentric circles. Due to the simple geometry of the forward problem, an analytic technique using conformal mapping and separation of variables has been employed. (C) 2002 John Wiley Sons, Inc.

The GP problem: quantifying gene-to-phenotype relationships

In this paper we refer to the gene-to-phenotype modeling challenge as the GP problem. Integrating information across levels of organization within a genotype-environment system is a major challenge in computational biology. However, resolving the GP problem is a fundamental requirement if we are to understand and predict phenotypes given knowledge of the genome and model dynamic properties of biological systems. Organisms are consequences of this integration, and it is a major property of biological systems that underlies the responses we observe. We discuss the E(NK) model as a framework for investigation of the GP problem and the prediction of system properties at different levels of organization. We apply this quantitative framework to an investigation of the processes involved in genetic improvement of plants for agriculture. In our analysis, N genes determine the genetic variation for a set of traits that are responsible for plant adaptation to E environment-types within a target population of environments. The N genes can interact in epistatic NK gene-networks through the way that they influence plant growth and development processes within a dynamic crop growth model. We use a sorghum crop growth model, available within the APSIM agricultural production systems simulation model, to integrate the gene-environment interactions that occur during growth and development and to predict genotype-to-phenotype relationships for a given E(NK) model. Directional selection is then applied to the population of genotypes, based on their predicted phenotypes, to simulate the dynamic aspects of genetic improvement by a plant-breeding program. The outcomes of the simulated breeding are evaluated across cycles of selection in terms of the changes in allele frequencies for the N genes and the genotypic and phenotypic values of the populations of genotypes.

Couple communication and female problem drinking: A behavioral observation study

Couples with alcohol and relationship problems often report poor communication, yet little is known about the communication of maritally distressed couples in which the woman abuses alcohol (MDWA couples). Compared with maritally distressed couples without alcohol problems (MDNA) and couples with neither problem (NDNA), MDWA couples showed a distinctive pattern of negative communication. Similar to MDNA men, MDWA men spoke negatively to their partners but listened positively to their partners much like NDNA men. MDWA women listened negatively, much as MDNA women did, but spoke positively, like NDNA women did. The interactions of MDWA couples can be characterized as a male-demand-female-withdraw pattern, which is a gender reversal of the female-demand-male-withdraw pattern often observed in MDNA couples.

Stressful animal housing conditions and their potential effect on sympathetic neurotransmission in mice

Although the sympathetic nervous system (SNS) plays a major role in mediating the peripheral stress response, due consideration is not usually given to the effects of prolonged stress on the SNS. The present study examined changes in neurotransmission in the SNS after exposure of mice (BALB/c) to stressful housing conditions. Focal extracellular recording of excitatory junction currents (EJCs) was used as a relative measure of neurotransmitter release from different regions of large surface areas of the mouse vas deferens. Mice were either group housed (control), isolation housed (social deprivation), group housed in a room containing rats (rat odor stress), or isolation housed in a room containing rats (concurrent stress). Social deprivation and concurrent stressors induced an increase of 30 and 335% in EJC amplitude, respectively. The success rate of recording EJCs from sets of varicosities in the concurrent stressor group was greater compared with all other groups. The present study has shown that some common animal housing conditions act as stressors and induce significant changes in sympathetic neurotransmission.

Quasiequilibrium problem in H-spaces

In the present paper, we study the quasiequilibrium problem and generalized quasiequilibrium problem of generalized quasi-variational inequality in H-spaces by a new method. Some new equilibrium existence theorems are given. Our results are different from corresponding given results or contain some recent results as their special cases. (C) 2003 Elsevier Science Ltd. All rights reserved.