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Significant Insights (significant + insight)
Selected AbstractsThe two-user Gaussian interference channel: a deterministic view,EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2008Guy Bresler This paper explores the two-user Gaussian interference channel through the lens of a natural deterministic channel model. The main result is that the deterministic channel uniformly approximates the Gaussian channel, the capacity regions differing by a universal constant. The problem of finding the capacity of the Gaussian channel to within a constant error is therefore reduced to that of finding the capacity of the far simpler deterministic channel. Thus, the paper provides an alternative derivation of the recent constant gap capacity characterisation of Etkin, Tse and Wang. Additionally, the deterministic model gives significant insight towards the Gaussian channel. Copyright © 2008 John Wiley & Sons, Ltd. [source] Intramitochondrial crystalline inclusions in nonalcoholic steatohepatitis,HEPATOLOGY, Issue 6 2009Stephen H. Caldwell Mitochondrial dysfunction is an important element in the pathogenesis of nonalcoholic steatohepatitis (NASH). Intramitochondrial crystals (IMCs) are a well-documented morphological abnormality seen on transmission electron microscopy in this disease. It has been suggested that IMCs consist of phospholipids, but their exact composition remain uncertain many years after their discovery. Micellar phase transitions of phospholipid bilayers is a well-known but little-studied phenomenon in living systems. Its presence in the mitochondria of NASH would offer significant insight into the disease with possible therapeutic implications. We postulated that intramitochondrial disturbances in NASH are sufficient to produce such transitions and that their detection in fresh biopsies would therefore be a dynamic process. To test this, we performed a blinded, prospective analysis of fresh liver biopsy samples immediately fixed under different conditions. Quantitative transmission electron microscopy morphometry, performed by systematically counting total mitochondria and IMCs within areas of uniform dimension, showed a stepwise decline in IMCs with cooler fixation temperature in each subject studied. Randomization testing (Monte Carlo resampling) confirmed that the detection of IMCs was strongly dependent on fixation temperature (P < 0.0001). Conclusion: These results indicate that the intramitochondrial crystals characteristic of NASH are highly dynamic and unstable structures. The findings offer the strongest support yet for their origin in micellar phase transitions. We speculate that such transitions result from microenvironmental changes within the mitochondria and carry therapeutic implications, especially in regard to dietary manipulations of mitochondrial lipid composition. (HEPATOLOGY 2009.) [source] Online pattern recognition based on a generalized hidden Markov model for intraoperative vital sign monitoringINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 5 2010Ping Yang Abstract The trend patterns of vital signs provide significant insight into the interpretation of intraoperative physiological measurements. We have modeled the trend signal of a vital sign parameter as a generalized hidden Markov model (also known as a hidden semi-Markov model). This model treats a time series as a sequence of predefined patterns and describes the transition between these patterns as a first-order Markov process and the intra-segmental variations as different dynamic linear systems. Based on this model, a switching Kalman smoother combines a Bayesian inference process with a fixed-point Kalman smoother in order to estimate the unconditional true signal values and generates the probability of occurrence for each pattern online. The probabilities of pattern transitions are tested against a threshold to detect change points. A second-order generalized pseudo-Bayesian algorithm is used to summarize the state propagation over time and reduces the computational overhead. The memory complexity is reduced using linked tables. The algorithm was tested on 30 simulated signals and 10 non-invasive-mean-blood-pressure trend signals collected at a local hospital. In the simulated test, the algorithm achieved a high accuracy of signal estimation and pattern recognition. In the test on clinical data, the change directions of 45 trend segments, out of the 54 segments annotated by an expert, were correctly detected with the best performing threshold, and with the introduction of only 8 false-positive detections. The proposed method can detect the changes of trend patterns in a time series online, while generating quantitative evaluation of the significance of detection. This method is promising for physiological monitoring as the method not only generates early alerts, but also summarizes the temporal contextual information for a high-level decision support system. Copyright © 2009 John Wiley & Sons, Ltd. [source] Exploring the relationship between nursing protocols and nursing practice in an Irish intensive care unitINTERNATIONAL JOURNAL OF NURSING PRACTICE, Issue 4 2005Angela V Flynn RGN BSc(Hons) PGDip(Ed) MSc Nursing practice no longer relies on tradition or ritual; instead, it is based on research and empirical evidence. The emphasis on evidence-based nursing, as well as standardization of nursing practice, has resulted in the production of policies, protocols and guidelines aimed at directing numerous aspects of nursing care. The aim of this study was to explore the relationship between these documents and actual nursing practice. To this end, this descriptive study employed a case study approach to examine the experiences of nurses in an Irish intensive care unit with a protocol on endotracheal tube suctioning. Focus group interviews of 17 nurses in six focus groups provided a significant insight into the experiences of these nurses in relation to policies, protocols and guidelines. Analysis of the data afforded some highly relevant findings, including the fact that nurses adapt clinical protocols as they see fit, thus demonstrating the importance that they place on their own professional judgement and autonomy. [source] Convenient expression of the rate constant for nonadiabatic transitionINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2005Yoshishige Okuno Abstract We derived a convenient expression of the rate constant for nonadiabatic transitions, with the intention of making it possible and practical to calculate the rate constant. For this derivation, we first assume that the seam, at which the adiabatic potential energy surfaces of reactant and product electronic states exhibit an avoided crossing, corresponds to the dividing surface of the nonadiabatic transition. Second, we use the probability that a nonadiabatic transition occurs in the seam. Third, the partition function in the seam is described by the local profile of the adiabatic potential energy surfaces of both the reactant and product electronic states. The rate constant expression thus derived not only gives significant insight into understanding nonadiabatic transitions, but also makes it possible to obtain a rough estimate of the rate constant. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source] The Family of GFP-Like Proteins: Structure, Function, Photophysics and Biosensor Applications.PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2006Introduction, Perspective ABSTRACT In this issue, we offer a symposium-in-print that is focused on several new advancements in fundamental research related to the family of GFP (green fluorescent protein)-like proteins. A few applied aspects are also included to illustrate the impact this amazing set of colored proteins has made on our understanding of cell biology at the molecular level. The six articles presented here cut across several disciplines ranging from biological function to protein structure to photophysical aspects. These highly original pieces of work include both experimental and computational approaches, and will provide the reader with significant insight into current, state-of-the-art research activities in this very dynamic and fast-paced field. In the first part of this perspective, I will give a brief overview of the history and salient features of GFPs, cite some examples that illustrate their impact on biotechnology, and provide a brief review of the structural and chemical features that lend these proteins their fascinating appearance. In the second part, I will introduce each of the peer-reviewed contributions of the participating authors. [source] The dynamics of development and evolution: Insights from behavioral embryologyDEVELOPMENTAL PSYCHOBIOLOGY, Issue 8 2007Robert Lickliter Abstract The perspective that features of species-typical behavior could be traced to experience that occurred prenatally was raised by Zing-Yang Kuo [1921 Journal of Philosophy 18: 645,664] early in the last century and Gilbert Gottlieb subsequently elaborated on and provided empirical support for this idea over the course of more than four decades of innovative psychobiological research. Although we are still a long way from fully understanding the specific pathways and processes by which prenatal experience can influence postnatal development, Gottlieb's research with precocial birds provided significant insights into the conditions and experiences of prenatal development involved in the achievement of species-typical perception and behavior. In particular, his elegant series of studies on the development of species identification in ducklings documented how the features and patterns of recurring prenatal sensory experience (including self-stimulation) guide and constrain the young individual's selective attention, perception, learning, and memory during both prenatal and postnatal periods. I review how this body of research supports the view that the structure and functions of the developing organism and its developmental ecology together form a relationship of mutual influence on the emergence, maintenance, and transformation of species-typical behavior. I also explore how Gottlieb's empirical demonstrations of the prenatal roots of so-called "instinctive" behavior provided a foundation for his conceptual efforts to define the links between developmental and evolutionary change. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 749,757, 2007. [source] Scales of association: hierarchical linear models and the measurement of ecological systemsECOLOGY LETTERS, Issue 6 2007Sean M. McMahon Abstract A fundamental challenge to understanding patterns in ecological systems lies in employing methods that can analyse, test and draw inference from measured associations between variables across scales. Hierarchical linear models (HLM) use advanced estimation algorithms to measure regression relationships and variance,covariance parameters in hierarchically structured data. Although hierarchical models have occasionally been used in the analysis of ecological data, their full potential to describe scales of association, diagnose variance explained, and to partition uncertainty has not been employed. In this paper we argue that the use of the HLM framework can enable significantly improved inference about ecological processes across levels of organization. After briefly describing the principals behind HLM, we give two examples that demonstrate a protocol for building hierarchical models and answering questions about the relationships between variables at multiple scales. The first example employs maximum likelihood methods to construct a two-level linear model predicting herbivore damage to a perennial plant at the individual- and patch-scale; the second example uses Bayesian estimation techniques to develop a three-level logistic model of plant flowering probability across individual plants, microsites and populations. HLM model development and diagnostics illustrate the importance of incorporating scale when modelling associations in ecological systems and offer a sophisticated yet accessible method for studies of populations, communities and ecosystems. We suggest that a greater coupling of hierarchical study designs and hierarchical analysis will yield significant insights on how ecological processes operate across scales. [source] Understanding NHS Reform: The Policy-Transfer, Social Learning, and Path-Dependency PerspectivesGOVERNANCE, Issue 2 2002Ian GreenerArticle first published online: 17 DEC 200 This paper utilizes three perspectives in analyzing health policy in the U.K. during the formulation of the "internal market" reforms of the late 1980s and early 1990s: policy transfer, social learning, and path-dependency. By doing so, it attempts to incorporate the most significant insights from each perspective to construct a framework for analysis that better illuminates the actors, processes, and constraints involved in health policy reform, as well as providing a means of assessing its importance. I suggest that the reform process in the U.K. was considerably more complex than most existing accounts suggest, and that notions such as "conjuncture" require caution in their usage in order to avoid confusion between the contingent and relatively permanent factors that allow reform to occur. [source] ,-Interferons and the single nucleotide polymorphisms: A milestone to tailor-made therapy for chronic hepatitis CHEPATOLOGY RESEARCH, Issue 5 2010Yasuhito Tanaka Type III interferons (IFN) (IFN-,1, -,2, -,3/interleukin [IL]-29, -28A, -28B) are cytokines with type I IFN-like antiviral activities. Most cells have expressed both type I and III IFN following Toll-like receptor (TLR) stimulation or viral infection, whereas the ability of cells to respond to IFN-, was restricted to a specific subset of cells. It was reported that signal transduction pathway of IFN-, was similar to that of IFN-,/, although a receptor adapted by IFN-, were distinct from that of IFN-,/,. However, the clinical significance and the role of each IFN-, were unclear. Recent genome-wide association studies (GWAS) of the human whole genome revealed several single nucleotide polymorphism sites (SNP) strongly associated with the response to pegylated IFN-, (PEG-IFN) plus ribavirin (RBV) treatment in chronic hepatitis C patients. The SNP, which are located near the IL-28B gene of chromosome 19, were discovered simultaneously by three independent studies opening a new prospective in hepatitis C research. The present review highlights significant insights that can be derived from the GWAS approach, and summarizes current knowledge of in vitro and in vivo study on the role of IFN-, in antiviral effect. [source] Adaptive restoration of sand-mined areas for biological conservationJOURNAL OF APPLIED ECOLOGY, Issue 1 2005JASON CUMMINGS Summary 1Adaptive management approaches to ecological restoration are current best practice. The usefulness of such an approach was tested in this study by implementing repeated experiments that examined restoration options for derelict sand mine sites dominated by Imperata cylindrica. Reclamation of degraded land that is dominated by I. cylindrica is a common problem throughout the tropics. 2Initially, the hypothesized barrier to regeneration was limited seedling establishment because of I. cylindrica competition. After burning the grassland, woody weed control and planting of seedlings were implemented in factorial combination. 3Seedling survival 28 months after planting averaged 26%, with < 1% of all seedlings establishing to a height > 1 m. The hypothesis that a transition barrier comprising solely biotic interactions restricted regeneration of native woody cover was rejected after seedlings and natural regeneration failed to thrive in this experiment. 4A revised hypothesis, that the transition barrier comprised a combination of abiotic limitations (soil deficiencies) and biotic interactions (Wallabia bicolor browsing and I. cylindrica competition), was developed. A second experiment tested this hypothesis by removing W. bicolor (fencing), slashing the I. cylindrica, adding organic mulch and planting a mixture of native pioneer and secondary successional woody species in factorial combination. 5Seedling survival was 61% in the second experiment and mulching significantly enhanced the survival and growth of all planted species. Planting alone reduced the regeneration of I. cylindrica after slashing. Native woody cover establishment was maximized by planting seedlings in mulched treatments. 6Synthesis and applications. Taken together, these experiments support the hypothesis that there is a barrier restricting regeneration of native woody cover, and the barrier probably comprises both abiotic and biotic components. By adopting an adaptive management approach to the ecological restoration of sites, significant insights into their management requirements have been gained, supporting the current best practice restoration framework. Insights gained through monitoring and adaptation will be used to update the reserve plan of management, enhancing restoration of this severely degraded area and promoting connectivity of native woody cover within the conservation estate. [source] Actions of Acute and Chronic Ethanol on Presynaptic TerminalsALCOHOLISM, Issue 2 2006Marisa Roberto This article presents the proceedings of a symposium entitled "The Tipsy Terminal: Presynaptic Effects of Ethanol" (held at the annual meeting of the Research Society on Alcoholism, in Santa Barbara, CA, June 27, 2005). The objective of this symposium was to focus on a cellular site of ethanol action underrepresented in the alcohol literature, but quickly becoming a "hot" topic. The chairs of the session were Marisa Roberto and George Robert Siggins. Our speakers were chosen on the basis of the diverse electrophysiological and other methods used to discern the effects of acute and chronic ethanol on presynaptic terminals and on the basis of significant insights that their data provide for understanding ethanol actions on neurons in general, as mechanisms underlying problematic behavioral effects of alcohol. The 5 presenters drew from their recent studies examining the effects of acute and chronic ethanol using a range of sophisticated methods from electrophysiological analysis of paired-pulse facilitation and spontaneous and miniature synaptic currents (Drs. Weiner, Valenzuela, Zhu, and Morrisett), to direct recording of ion channel activity and peptide release from acutely isolated synaptic terminals (Dr. Treistman), to direct microscopic observation of vesicular release (Dr. Morrisett). They showed that ethanol administration could both increase and decrease the probability of release of different transmitters from synaptic terminals. The effects of ethanol on synaptic terminals could often be correlated with important behavioral or developmental actions of alcohol. These and other novel findings suggest that future analyses of synaptic effects of ethanol should attempt to ascertain, in multiple brain regions, the role of presynaptic terminals, relevant presynaptic receptors and signal transduction linkages, exocytotic mechanisms, and their involvement in alcohol's behavioral actions. Such studies could lead to new treatment strategies for alcohol intoxication, alcohol abuse, and alcoholism. [source] The Hsp70 chaperone machines of Escherichia coli: a paradigm for the repartition of chaperone functionsMOLECULAR MICROBIOLOGY, Issue 4 2007Pierre Genevaux Summary Molecular chaperones are highly conserved in all free-living organisms. There are many types of chaperones, and most are conveniently grouped into families. Genome sequencing has revealed that many organisms contain multiple members of both the DnaK (Hsp70) family and their partner J-domain protein (JDP) cochaperone, belonging to the DnaJ (Hsp40) family. Escherichia coli K-12 encodes three Hsp70 genes and six JDP genes. The coexistence of these chaperones in the same cytosol suggests that certain chaperone,cochaperone interactions are permitted, and that chaperone tasks and their regulation have become specialized over the course of evolution. Extensive genetic and biochemical analyses have greatly expanded knowledge of chaperone tasking in this organism. In particular, recent advances in structure determination have led to significant insights of the underlying complexities and functional elegance of the Hsp70 chaperone machine. [source] Relations of sugar composition and ,13C in phloem sap to growth and physiological performance of Eucalyptus globulus (Labill)PLANT CELL & ENVIRONMENT, Issue 8 2010ANDREW MERCHANT ABSTRACT We characterized differences in carbon isotopic content (,13C) and sugar concentrations in phloem exudates from Eucalyptus globulus (Labill) plantations across a rainfall gradient in south-western Australia. Phloem sap ,13C and sugar concentrations varied with season and annual rainfall. Annual bole growth was negatively related to phloem sap ,13C during summer, suggesting a water limitation, yet was positively related in winter. We conclude that when water is abundant, variations in carboxylation rates become significant to overall growth. Concentrations of sucrose in phloem sap varied across sites by up to 600 mm, and raffinose by 300 mm. These compounds play significant roles in maintaining osmotic balance and facilitating carbon movement into the phloem, and their relative abundances contribute strongly to overall ,13C of phloem sap. Taken together, the ,13C and concentrations of specific sugars in phloem sap provide significant insights to functions supporting growth at the tree, site and landscape scale. [source] Proteomic strategies to elucidate pathogenic mechanisms of spirochetesPROTEOMICS - CLINICAL APPLICATIONS, Issue 9 2007Jarlath E. Nally Dr. Abstract Spirochetes are a unique group of bacteria that include several motile and highly invasive pathogens that cause a multitude of acute and chronic disease processes. Nine genomes of spirochetes have been completed, which provide significant insights into pathogenic mechanisms of disease and reflect an often complex lifestyle associated with a wide range of environmental and host factors encountered during disease transmission and infection. Characterization of the outer membrane of spirochetes is of particular interest since it interacts directly with the host and environs during disease and likely contains candidate vaccinogens and diagnostics. In concert with appropriate fractionation techniques, the tools of proteomics have rapidly evolved to characterize the proteome of spirochetes. Of greater significance, studies have confirmed the differential expression of many proteins, including those of the outer membrane, in response to environmental signals encountered during disease transmission and infection. Characterization of the proteome in response to such signals provides novel insights to understand pathogenic mechanisms of spirochetes. [source] Application of Laser-Assisted Microdissection for Gene Expression Analysis of Mammalian Germ CellsANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 3 2010R. Kenngott With 1 figure and 2 tables Summary Laser-assisted microdissection (LAM) is an important method to provide new significant insights into many embryological processes. To understand these processes, it is important to obtain specific populations of cells from complex tissue in an efficient and precise manner and to combine with many different molecular biological methods. During the last few years, the sophistication of the techniques of LAM has increased significantly and made the procedure easy to use. New micro-extraction protocols for DNA, RNA and proteins now allow broad downstream applications in the fields of genomics, transcriptomics and proteomics. In this review, we give a short overview of the application of LAM in combination with quantitative qPCR for the analysis of gene expression in mammalian germ cells. [source] Women of Steel: Constructing and Contesting New Gendered Geographies of Work in the Australian Steel IndustryANTIPODE, Issue 2 2000Liza Tonkin The article argues that although structuralist-inspired approaches to steel restructuring have provided significant insights and recognised the role of "labour" in sectoral change, such studies have predominantly equated labour politics with unionism, downplaying the impact of other forms of workers' politics. This has created a problematic disjunction between "real world" events and academic research, with ensuing issues for policy development and delivery. In response to this difficulty, the paper builds on Herod's concept of a labour geography to develop multiple labour geographies of power, an approach that describes different forms of workers' politics. To illustrate this approach, the paper presents female steelworkers' politics of restructuring. It details the Jobs for Women Campaign in Wollongong, Australia, a 1980s place-based initiative that sought to gain blue-collar employment for women in the local steelworks. The study demonstrates how female steelworkers developed restructuring politics addressing gender and employment discrimination, issues not normally associated with labour politics. The paper concludes that such workers' struggles need to be analysed as they affect restructuring impacts and processes. [source] Macrocyclic Cyclooctene-Supported AlCl,Salen Catalysts for Conjugated Addition Reactions: Effect of Linker and Support Structure on CatalysisCHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2009Nandita Madhavan Dr. Abstract AlCl,salen (salen=N,N,-bis(salicylidene)ethylenediamine dianion) catalysts supported onto macrocyclic oligomeric cyclooctene through linkers of varying length and flexibility have been developed to demonstrate the importance of support architecture on catalyst activity. The role played by the support and the linkers in dictating catalyst activity was found to vary for reactions with contrasting mechanisms, such as the bimetallic cyanide and the monometallic indole addition reactions. While the flexible support significantly enhanced the cyanide addition reaction, most likely by improving salen,salen interactions in the transition state, it lowered the reaction rate for the monometallic indole reaction. For both reactions, significant increase in catalytic activity was observed for catalysts with the longest linkers. The effect of the flexible macrocyclic support on catalysis was further exemplified by the enhanced activity of the supported catalyst in comparison with its unsupported analogue for the conjugate addition of tetrazoles, which is known to be catalyzed by dimeric ,-oxo,salen catalysts. Our studies with the cyclooctene supported AlCl,salen catalysts provides significant insights for rationally designing highly efficient AlCl,salen catalysts for a diverse set of reactions. [source] | ||||||||||||||||||||||