112 research outputs found
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No full textTo quantify gene regulation, a function is required that relates transcription factor binding to DNA (input) to the rate of mRNA synthesis from a target gene (output). Such a 'gene regulation function' (GRF) generally cannot be measured because the experimental titration of inputs and simultaneous readout of outputs is difficult. Here we show that GRFs may instead be inferred from natural changes in cellular gene expression, as exemplified for the cell cycle in the yeast S. cerevisiae. We develop this inference approach based on a time series of mRNA synthesis rates from a synchronized population of cells observed over three cell cycles. We first estimate the functional form of how input transcription factors determine mRNA output and then derive GRFs for target genes in the clb2 gene cluster that are expressed during G2/M phase. Systematic analysis of additional GRFs suggests a network architecture that rationalizes transcriptional cell cycle oscillations. We find that a transcription factor network alone can produce oscillations in mRNA expression, but that additional input from cyclin oscillations is required to arrive at the native behaviour of the cell cycle oscillator
Hotspots and Coldspots: Household and village-level variation in orphanhood prevalence in rural Malawi
No full textWe explore the spatial distribution of orphans in two areas of Malawi. We first review pertinent themes in qualitative data collected in our research sites. Then, using spatial analysis, we show how positive and negative clusters of orphans—which we term orphanhood "hotspots" and "coldspots"—can be found at the village and sub-village levels. In the third and longest section of the paper, and using multilevel analyses with both simple and complex variance structures, we evaluate the relationship between the presence of orphans and a range of individual, household and village-level characteristics, including households' spatial relationship to each other and to other local sites of significance. This series of analyses shows that the most important covariates of orphan presence are the density of settlement, household size, and religious characteristics, with the latter measured simultaneously at both household and village-level. Other characteristics like education, reported mortality levels and HIV infection, are wholly unrelated to orphan prevalence at all analytic levels. Wealth and various spatial characteristics are only marginally associated with orphan prevalence. We conclude by reviewing some difficulties in explaining causal mechanisms underlying these observed relationships, and discussing conceptual, theoretical and programmatic implications.Africa, AIDS/HIV, Malawi, multilevel model, orphan prevalence, orphans, spatial analysis
Klassifikationsgestützte on-line Adaption eines robusten beobachterbasierten Fehlerdiagnoseansatzes für nichtlineare Systeme
No full textZugl.: Kassel, Univ., Diss. 201
Enzymes provide demographers with food for thought.
No full textLife expectancy has increased by 20 years since the middle of the last century, but children under five have fared better than adult males
Control-oriented modeling of hydrostatic power-split CVTs using Takagi-Sugeno fuzzy models
No full text
A SYSTEMATIC LOAD IDENTIFICATION PROCEDURE FOR PARALLEL ROBOT MANIPULATORS
No full textThis paper presents a systematic load identification procedure for a class of parallel robot manipulators. It is considered as a regular dynamic robot identification problem since the load is rigidly fixed on the robot-platform. The challenge is that the estimation must be based only on the measurements obtained through sensors in the robot actuators. The load identification procedure is exemplified by experimental studies with a calibrated test load using periodic robot excitation
Observer Design Using T-S Fuzzy Systems for Pressure Estimation in Hydrostatic Transmissions
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