The precision of regulation in Dictyostelium discoideum: implications for cell-type proportioning in the absence of spatial pattern

We have made careful counts of the exact number of spore, stalk and basal disc cells in small fruiting bodies of Dictyostelium discoideum (undifferentiated amoebae are found only rarely and on average their fraction is 4.96 x 10(-4)). (i) Within aggregates of a given size, the relative apportioning of amoebae to the main cell types occurs with a remarkable degree of precision. In most cases the coefficient of variation (c.v.) in the mean fraction of cells that form spores is within 4.86%. The contribution of stalk and basal disc cells is highly variable when considered separately (c.v.'s upto 25% and 100%, respectively), but markedly less so when considered together. Calculations based on theoretical models indicate that purely cell-autonomous specification of cell fate cannot account for the observed accuracy of proportioning. Cell-autonomous determination to a prestalk or prespore condition followed by cell type interconversion, and stabilised by feedbacks, suffices to explain the measured accuracy. (ii) The fraction of amoebae that differentiates into spores increases monotonically with the total number of cells. This fraction rises from an average of 73.6% for total cell numbers below 30 and reaches 86.0% for cell numbers between 170 and 200 (it remains steady thereafter at around 86%). Correspondingly, the fraction of amoebae differentiating into stalk or basal disc decreases with total size. These trends are in accordance with evolutionary expectations and imply that a mechanism for sensing the overall size of the aggregate also plays an essential role in the determination of cell-type proportions

Software Stress Assessment Test: A Preliminary Investigation

Though research on stress has been on the increase in recent years, occupational stress literature is based, to a large extent, on individual perception rather than substantiated fact. The present study was undertaken with the objective of developing a stress assessment test for the software professional. The test consists of 57 items covering four factors namely, job-related, organisational, personal and behavioural. The test was administered to 33 software specialists from a software firm in Bangalore. Based on the data, percentile norms were established. The scale was subjected to reliability test. The split half reliability is 0.816**. Work is currently on in the area and further research is required in this direction. Individual moves into a state of exhaustion, from which tissue breakdown and even death can result. In other words, continued stress can lead to bodily damage. The body manifests the stress reaction by a rise in blood pressure, increased adrenaline, changed heartbeat, more RBCs, slower digestion, and so on. However, Selye argued that a moderate amount of stress could be a positive experience while too little stress could be negative

Web-based Finance and Accounting System

This project is focused on developing a web-based application for Finace and Accounts department, NAL.13; The main objective of the project is to replace the existing manual system to an automated electronic system

Thermal microenvironment of keratinocytes and fibroblasts during cauterization by laser devices

International audienc

WEB Pages for NAL

An attempt has been made to create NAL Web pages using HTML and Javascript. An INDY machine with Netscape 30 is used as a browser. IBM RS/6000 model 41T is used as a web server. Both of them are on FDDI/ETHERNET link

Intranet based telephone directory software

This document is a step-by-step manual to educate the user on working with NAVs telephone directory on the intranet. This system discussed here is an improvement over telephone directory which used Java and Applet for connectvity. Our new system uses Java, Servlet and Oracle

Confirmatory factor analysis of the GHQ-12: can I see that again

Objective: this paper reviews research relating to the factor analysis of the GHQ-12. We explore the question of whether there is a consistent replicable structure to the GHQ-12 using: (i) a comparative analysis of fit between identified factor models; and (ii) a confirmatory factor analysis of GHQ-12 data from our own study.\ud \ud Method: the factor models proposed from the literature were reviewed. The published factor loadings were used to carry out a factor matching analysis to identify similarities between the various factor models that have been identified. In addition, 490 patients visiting their general practitioner completed the General Health Questionnaire (GHQ-12) in the first phase of a longitudinal study evaluating service delivery to rural Tasmania. Three different methods for scoring the GHQ-12 were utilized and each resultant data set was analysed using a Confirmatory Factor Analysis (CFA) to establish which of the various factor models provided the most consistent description of the data.\ud \ud Result: none of the complete factor models that have been proposed have been consistently replicated across studies. Isolated factors were replicated between some studies but no single factor structure was replicated across all studies. All of the models had adequate fit to the Tasmanian data when the usual scoring was used. However, only one model had a consistently high 'goodness of fit' across scoring methods.\ud \ud Conclusion: it was concluded that the 'best fit' was achieved by a model based on an early factor analytic study using an Australian sample. It was suggested that researchers wanting to extract scales from the GHQ-12 could use this model