A reliable measure of similarity based on dependency for short time series: an application to gene expression networks

Background: Microarray techniques have become an important tool to the investigation of genetic relationships and the assignment of different phenotypes. Since microarrays are still very expensive, most of the experiments are performed with small samples. This paper introduces a method to quantify dependency between data series composed of few sample points. The method is used to construct gene co-expression subnetworks of highly significant edges. Results: The results shown here are for an adapted subset of a Saccharomyces cerevisiae gene expression data set with low temporal resolution and poor statistics. The method reveals common transcription factors with a high confidence level and allows the construction of subnetworks with high biological relevance that reveals characteristic features of the processes driving the organism adaptations to specific environmental conditions. Conclusion: Our method allows a reliable and sophisticated analysis of microarray data even under severe constraints. The utilization of systems biology improves the biologists ability to elucidate the mechanisms underlying celular processes and to formulate new hypotheses.

Direct visualisation of B-1 inhomogeneity by flip angle dependency

Inhomogeneities in the spatial distribution of the excitatory Radio Frequency (RF) field, are still a dominant source of artifacts and loss of signal to noise ratio in MR imaging experiments, A number of strategies have been proposed to quantify this distribution, However, in this technical note we present a relatively simple MR imaging procedure which can be used to visualise RF inhomogeneities directly either by means of the magnitude or the phase of an image. To visualise the RF field distribution in both the inner and outer volumes of the coil, we have performed experiments in which the entire coil is submerged in a non-conducting fluid, To the best of our knowledge this strategy has not been used previously in order to evaluate coil performance, Finally, we demonstrate that the method is sensitive enough to reveal the effects of the sample properties on the effective RF wavelength of the transmitted field. (C) 1997 Elsevier Science Inc.

Intellectual origins of welfare dependency

'Welfare dependency' has become a key term in policy debate in the United States and, more recently, Australia. In this article I explore the intellectual origins of the term, looking specifically at the writings of George Gilder and Charles Murray, two commentators whose (often polemically presented) ideas were influential within the Reagan Administration and have been at the forefront of a conservative renewal in welfare debate generally. Although others have subsequently refined some of their arguments and proposals, the authors' central claim that welfare causes dependency and thus unemployment and poverty - and that welfare reform therefore needs to focus on changing the behaviour of welfare recipients rather than providing employment opportunities - has had a lasting political impact, in Australia as much as in the US.

High dependency units: Issues to consider in their planning

This review discusses the issues to be considered in establishing new or extending existing high dependency unit (HDU) services. A defined high dependency service becomes cost-effective when patient care requires more than one nurse for three patients. Professional guidelines for HDUs vary and there are no national accreditation criteria. Casemix and service delivery specifications for the HDU need to be defined and agreed upon within the institution. Establishing a new HDU service requires changes to care delivery. Many potential HDU patients are currently managed in general wards or in the intensive care unit. The service should be discussed widely and marketed within the institution, and the development of defined working relationships with the ICU and primary care teams oil the wards is mandatory.

Nonlinear optimization method for short-term hydro scheduling considering head-dependency

This paper is on the problem of short-term hydro scheduling, particularly concerning head-dependent reservoirs under competitive environment. We propose a new nonlinear optimization method to consider hydroelectric power generation as a function of water discharge and also of the head. Head-dependency is considered on short-term hydro scheduling in order to obtain more realistic and feasible results. The proposed method has been applied successfully to solve a case study based on one of the main Portuguese cascaded hydro systems, providing a higher profit at a negligible additional computation time in comparison with a linear optimization method that ignores head-dependency.

Scheduling of a hydro producer considering head-dependency, price scenarios and risk-aversion

In this paper, a mixed-integer quadratic programming approach is proposed for the short-term hydro scheduling problem, considering head-dependency, discontinuous operating regions and discharge ramping constraints. As new contributions to earlier studies, market uncertainty is introduced in the model via price scenarios, and risk aversion is also incorporated by limiting the volatility of the expected profit through the conditional value-at-risk. Our approach has been applied successfully to solve a case Study based on one of the main Portuguese cascaded hydro systems, requiring a negligible computational time.

Tradução, Adaptação e Validação da Escala Jones Dependency Tool

A avaliação do grau de dependência dos utentes é um dos aspectos que contribui para a melhoria dos cuidados, dado que permite uma melhor adequação dos recursos humanos às situações vivenciadas no quotidiano dos serviços de urgência. A carga de trabalho em enfermagem está estreitamente relacionada com o grau de dependência, pelo que a sua avaliação assume-se como um elemento fundamental numa politica de gestão de qualidade. Com o intuito de avaliar, numa fase inicial, o grau de dependência dos utentes que recorrem aos serviços de urgência foi criada uma escala – Jones Dependency Tool (JDT) – sendo que o objectivo major é a avaliação da carga de trabalho em Enfermagem relacionando com o grau de dependência dos utentes. O presente estudo visa traduzir, adaptar e validar para Portugal o referido instrumento. O estudo encontra-se dividido em duas partes. A primeira constituída pela tradução e adaptação cultural da JDT para língua portuguesa e a segunda, pela análise da fidelidade e da validade do instrumento. O processo de validação para a língua portuguesa ocorreu numa amostra de 129 utentes de dois serviços de urgência da região de lisboa. Através dos testes estatísticos realizados, a versão Portuguesa revelou-se um instrumento confiável e válido para a realização do grau de dependência dos utentes que recorrem ao serviço de urgência.

Genome-wide analysis of SREBP1 activity around the clock reveals its combined dependency on nutrient and circadian signals.

In mammals, the circadian clock allows them to anticipate and adapt physiology around the 24 hours. Conversely, metabolism and food consumption regulate the internal clock, pointing the existence of an intricate relationship between nutrient state and circadian homeostasis that is far from being understood. The Sterol Regulatory Element Binding Protein 1 (SREBP1) is a key regulator of lipid homeostasis. Hepatic SREBP1 function is influenced by the nutrient-response cycle, but also by the circadian machinery. To systematically understand how the interplay of circadian clock and nutrient-driven rhythm regulates SREBP1 activity, we evaluated the genome-wide binding of SREBP1 to its targets throughout the day in C57BL/6 mice. The recruitment of SREBP1 to the DNA showed a highly circadian behaviour, with a maximum during the fed status. However, the temporal expression of SREBP1 targets was not always synchronized with its binding pattern. In particular, different expression phases were observed for SREBP1 target genes depending on their function, suggesting the involvement of other transcription factors in their regulation. Binding sites for Hepatocyte Nuclear Factor 4 (HNF4) were specifically enriched in the close proximity of SREBP1 peaks of genes, whose expression was shifted by about 8 hours with respect to SREBP1 binding. Thus, the cross-talk between hepatic HNF4 and SREBP1 may underlie the expression timing of this subgroup of SREBP1 targets. Interestingly, the proper temporal expression profile of these genes was dramatically changed in Bmal1-/- mice upon time-restricted feeding, for which a rhythmic, but slightly delayed, binding of SREBP1 was maintained. Collectively, our results show that besides the nutrient-driven regulation of SREBP1 nuclear translocation, a second layer of modulation of SREBP1 transcriptional activity, strongly dependent from the circadian clock, exists. This system allows us to fine tune the expression timing of SREBP1 target genes, thus helping to temporally separate the different physiological processes in which these genes are involved.