Basic Understanding (basic + understanding)

Distribution by Scientific Domains

Selected Abstracts

Insulin resistance in sepsis

G. L. Carlson
Basic understanding of the phenomenon remains elusive [source]

Reflux injury of esophageal mucosa: experimental studies in animal models of esophagitis, Barrett's esophagus and esophageal adenocarcinoma

Yan Li
SUMMARY., Barrett's esophagus (BE), a gastroesophageal reflux associated complication, is defined as the replacement of normal esophageal squamous mucosa by specialized intestinal columnar mucosa with the appearance of goblet cells. The presence of BE is associated with an increased risk of developing esophageal adenocarcinoma (EAC). Although the exposure of gastroduodenal contents to the esophageal mucosa is considered to be an important risk factor for the development of esophagitis, BE and EAC, the mechanisms of reflux esophageal injury are not fully understood. Animal models are now being used extensively to identify the mechanisms of damage and to devise protective and mitigating strategies. Experimental studies on animal models by mimicking the processing of gastroesophageal reflux injury have bloomed during the past decades, however, there is controversy regarding which experimental model for reflux esophagitis, experimental BE and experimental EAC is best. In this review article we aim to clarify the basic understanding of gastroesophageal reflux injury and its complications of BE and EAC, as well as to present current understanding of the reflux experimental models. The animal models of experimental esophageal injury are summarized with focus on the surgical procedures to guide the investigator in choosing or developing a correct animal model in future studies. In addition, our own experimental studies of the animal models are also briefly discussed. [source]

Scale-dependence in species-area relationships

ECOGRAPHY, Issue 6 2005
Will R. Turner
Species-area relationships (SARs) are among the most studied phenomena in ecology, and are important both to our basic understanding of biodiversity and to improving our ability to conserve it. But despite many advances to date, our knowledge of how various factors contribute to SARs is limited, searches for single causal factors are often inconclusive, and true predictive power remains elusive. We believe that progress in these areas has been impeded by 1) an emphasis on single-factor approaches and thinking of factors underlying SARs as mutually exclusive hypotheses rather than potentially interacting processes, and 2) failure to place SAR-generating factors in a scale-dependent framework. We here review mathematical, ecological, and evolutionary factors contributing to species-area relationships, synthesizing major hypotheses from the literature in a scale-dependent context. We then highlight new research directions and unanswered questions raised by this scale-dependent synthesis. [source]

Towards predictive modelling of the electrophysiology of the heart

Edward Vigmond
The simulation of cardiac electrical function is an example of a successful integrative multiscale modelling approach that is directly relevant to human disease. Today we stand at the threshold of a new era, in which anatomically detailed, tomographically reconstructed models are being developed that integrate from the ion channel to the electromechanical interactions in the intact heart. Such models hold high promise for interpretation of clinical and physiological measurements, for improving the basic understanding of the mechanisms of dysfunction in disease, such as arrhythmias, myocardial ischaemia and heart failure, and for the development and performance optimization of medical devices. The goal of this article is to present an overview of current state-of-art advances towards predictive computational modelling of the heart as developed recently by the authors of this article. We first outline the methodology for constructing electrophysiological models of the heart. We then provide three examples that demonstrate the use of these models, focusing specifically on the mechanisms for arrhythmogenesis and defibrillation in the heart. These include: (1) uncovering the role of ventricular structure in defibrillation; (2) examining the contribution of Purkinje fibres to the failure of the shock; and (3) using magnetic resonance imaging reconstructed heart models to investigate the re-entrant circuits formed in the presence of an infarct scar. [source]

Activity and energetics of free-swimming fish: insights from electromyogram telemetry

Steven J Cooke
Abstract Electromyogram (EMG) telemetry studies that involve remotely monitoring the locomotory activity and energetics of fish are contributing important information to the conservation and management of fisheries resources. Here, we outline the development of this rapidly evolving field and formulate the studies conducted that utilize this technology. To date, more than 60 studies have been conducted using EMG telemetry that spans 18 species. Several general trends were observed in the methodology of the studies that we have highlighted as standards that should be adopted associated with transmitter customization, electrode placement and surgical technique. Although numerous studies have been methodological, there are still some deficiencies in our basic understanding of issues such as the need for individual calibration and the method of reporting or transforming data. Increasingly, this technology is being applied to address issues in conservation, management and aquaculture production. At present, the technology has been most frequently applied to the study of animal activity or energetics and to migration. Several recent studies have also focused on addressing more basic questions in ecological and evolutionary biology (e.g. parental care dynamics) similar to the large body of literature that has been collected for other taxa (e.g. marine mammals, birds), using activity telemetry. Collectively, studies conducted using EMG telemetry have contributed important information on free-swimming fish that was previously difficult to obtain. EMG telemetry is particularly effective for examining behaviour at temporal and spatial scales that are difficult using other techniques. The development of an ultrasonic transmitter based on the same proven principles as those used in the current radio transmitter technology will permit studies in other environments (i.e. marine, brackish, deep water) and on different species of fish. We encourage the continued development and refinement of devices for monitoring the activity and energetics of free-swimming fish, and also encourage researchers to consider EMG telemetry as a tool for addressing questions that are not effectively answered with other techniques. [source]

Ecological responses to altered flow regimes: a literature review to inform the science and management of environmental flows

Summary 1.,In an effort to develop quantitative relationships between various kinds of flow alteration and ecological responses, we reviewed 165 papers published over the last four decades, with a focus on more recent papers. Our aim was to determine if general relationships could be drawn from disparate case studies in the literature that might inform environmental flows science and management. 2.,For all 165 papers we characterised flow alteration in terms of magnitude, frequency, duration, timing and rate of change as reported by the individual studies. Ecological responses were characterised according to taxonomic identity (macroinvertebrates, fish, riparian vegetation) and type of response (abundance, diversity, demographic parameters). A ,qualitative' or narrative summary of the reported results strongly corroborated previous, less comprehensive, reviews by documenting strong and variable ecological responses to all types of flow alteration. Of the 165 papers, 152 (92%) reported decreased values for recorded ecological metrics in response to a variety of types of flow alteration, whereas 21 papers (13%) reported increased values. 3.,Fifty-five papers had information suitable for quantitative analysis of ecological response to flow alteration. Seventy per cent of these papers reported on alteration in flow magnitude, yielding a total of 65 data points suitable for analysis. The quantitative analysis provided some insight into the relative sensitivities of different ecological groups to alteration in flow magnitudes, but robust statistical relationships were not supported. Macroinvertebrates showed mixed responses to changes in flow magnitude, with abundance and diversity both increasing and decreasing in response to elevated flows and to reduced flows. Fish abundance, diversity and demographic rates consistently declined in response to both elevated and reduced flow magnitude. Riparian vegetation metrics both increased and decreased in response to reduced peak flows, with increases reflecting mostly enhanced non-woody vegetative cover or encroachment into the stream channel. 4.,Our analyses do not support the use of the existing global literature to develop general, transferable quantitative relationships between flow alteration and ecological response; however, they do support the inference that flow alteration is associated with ecological change and that the risk of ecological change increases with increasing magnitude of flow alteration. 5.,New sampling programs and analyses that target sites across well-defined gradients of flow alteration are needed to quantify ecological response and develop robust and general flow alteration,ecological response relationships. Similarly, the collection of pre- and post-alteration data for new water development programs would significantly add to our basic understanding of ecological responses to flow alteration. [source]

Action of Force on Rock Mass by Crack Water Pressure

Guntram Innerhofer Dipl.-Ing.
The formula of effective stress used in soil mechanics is adapted to the properties of rock mass by implementation of the wetting factor and the Saint-Venant factor. The wetting factor defines the area over which a hydrostatic force can actually be developed, the Saint Venant factor defines the component of this force which is balanced by reduction of the effective stress in the crack zone. Here, the consequences of this concept are discussed with respect to uniaxial, plain stress and a continuum mechanical model. The effect of the concept is considered in relation to the state of stress in crack zones, and in the adjacent rock mass, and on the action of forces on the system. The development of crack propagation and of shear failure is discussed. The intention is to contribute towards a basic understanding of the complex effects of water pressure in rock masses, applicable to engineering practice. Kraftwirkung des Kluftwasserdrucks auf Fels Die Formel für Effektivspannungen der Bodenmechanik wird, den Eigenschaften von Fels entsprechend, durch Einführen des Benetzungsgrads und des Saint-Venant-Faktors erweitert. Der Benetzungsgrad definiert die Fläche, auf die eine hydrostatische Kraft wirken kann, der Saint-Venant-Faktor die Komponente dieser Kraft, die in der Kluftfläche durch Reduktion der Effektivspannungen ausgeglichen wird. Die andere Komponente belastet das System. Anhand eines einachsigen, eines ebenen und eines Kontinuum-Mechanischen Modells werden die aus diesem Ansatz abgeleiteten Spannungszustände in der Kluftfläche beziehungsweise im klüftigen Fels diskutiert. Die Entwicklung von Kluftsprengung und Scherbruch und das Verhalten hoch- und tiefliegender Druckstollen werden beschrieben. Beabsichtigt ist, mit einer möglichst geschlossenen, auf das Wesentliche beschränkten Darstellung das Verständnis der komplexen Zusammenhänge zu fördern. [source]

The 80th anniversary of von Willebrand's disease: history, management and research

HAEMOPHILIA, Issue 6 2006
Summary., The history of von Willebrand's disease (VWD) is fascinating because it demonstrates how good clinical observations, genetic studies and biochemical skills can improve basic understanding of a disease and its management. The continuous efforts of scientists and clinicians during the last 80 years have significantly improved the knowledge of von Willebrand factor (VWF) structure and function and the management of VWD. Diagnosis of phenotype and genotype is now available in many countries and treatment is becoming more specific according to the VWD type. Any therapeutic agents must correct the dual defect of haemostasis, i.e. the abnormal platelet adhesion due to reduced and/or dysfunctional and low levels of factor VIII (FVIII) associated with VWF defects. Desmopressin (DDAVP) is the treatment of choice for type 1 VWD because it induces release of VWF from cellular compartments. Plasma virally inactivated VWF concentrates containing FVIII are effective and safe in patients unresponsive to DDAVP. There are advanced plans to develop a recombinant VWF but this product will require the concomitant administration of FVIII for the control of acute bleeds. Basic research studies on cellular biology, biochemistry and immunology have confirmed the role of VWF as a crucial participant in both haemostasis and thrombosis as its main biological activity is to support platelet adhesion,aggregation in the circulation. Retrospective and prospective clinical research studies, including bleeding history and laboratory markers for diagnosis as well as the use of DDAVP and VWF concentrates to manage or prevent bleeds in patients with VWD have been essential to provide general guidelines for VWD management. The large number of publications quoting VWD and VWF emphasizes the important role of VWF in medicine. [source]

Fair Trade Community Café

capitaux propres; erreurs comptables; petite entreprise; rentabilité Abstract This case concerns the real operations of a café in a small town in Nova Scotia, Canada. It is a second location of a theme restaurant, with the first location successfully operating for a number of years. The owner of the first location, and senior partner of the second café, is available for advice but does not participate in the day-to-day operations of the second location; there are two junior partners who run the business. The focus is on the financial statements generated by an external bookkeeping service. The income statement reports a significant loss, and some of the accounts on the balance sheet and income statement do not make sense for this type of business. Simple ratio and variance analysis provides information for students to determine where problems lie. The case presents a good opportunity for students who have a basic understanding of financial statements to read a set of real statements generated by a bookkeeping service. Not all transactions are logical for a small café, although the financial information is from a real café in operation. The case also contains industry information on the operations of small food and drinking businesses located in Nova Scotia. Fair Trade Community Café Résumé Le cas exposé par l'auteure a trait à l'exploitation d'un véritable café situé dans une petite ville de Nouvelle-Écosse, au Canada. Il s'agit du second établissement d'un restaurant à thème dont le premier établissement exerce ses activités avec succès depuis plusieurs années. Le propriétaire du premier établissement, et associé majoritaire du second, est disposéà prodiguer des conseils mais ne participe pas à l'exploitation quotidienne du second café, que dirigent deux associés minoritaires. Le cas porte sur les états financiers produits par un service externe de tenue des comptes. Le compte de résultat fait état d'une perte importante, et certains des comptes du bilan et des postes du compte de résultat ne conviennent pas à ce type d'entreprise. Une simple analyse des ratios et des écarts fournit de l'information permettant aux étudiants de diagnostiquer les problèmes qui se posent. Le cas offre aux étudiants possédant une connaissance de base de la façon dont les états financiers sont établis une excellente occasion de lire un jeu d'états financiers véritables, produits par un service de tenue des comptes. Toutes les opérations ne sont pas logiquement celles d'un petit café, bien que les données financières proviennent d'un établissement authentique. Le cas contient également des informations sectorielles sur les activités de petites entreprises du secteur de l'alimentation établies en Nouvelle-Écosse. [source]

The praxis of clinical knowledge: Learning to care for paediatric patients with a congenital heart anomaly

Suzi Robertson-Malt RN PhD BN(Hons)
In Saudi Arabia, the major tertiary care unit for the treatment of cardiovascular disease is the King Faisal Heart Institute (KFHI). Its state of the art technology and patient profile facilitates nurses to become highly knowledgeable in the diversity of treatment modalities and nursing care of a range of paediatric pathology. Like many global nursing organizations, the KFHI is experiencing nursing shortages and nurses coming to work in this highly specialized area are lacking some of the basic understanding and skills development necessary to work efficiently and effectively in the area. This paper describes the work of the cardiovascular education team in developing a praxis-based curriculum that equips nurses to not only function at a high level in the cardiovascular area but also facilitate success in their future careers when they leave Saudi Arabia. [source]

NF- ,B in liver diseases: a target for drug therapy

Pablo Muriel
Abstract There are five nuclear factor- ,B (NF- ,B) transcription factors with important roles in innate immunity, liver inflammation, fibrosis and apoptosis prevention. Several inhibitors of NF- ,B, like caffeic acid, captopril, curcumin, pyrrolidine dithiocarbamate, resveratrol, silymarin and thalidomide, have demonstrated antinecrotic, anticholestatic, antifibrotic and anticancer activities in the liver. A link between inflammation and hepatocellular carcinoma through the NF- ,B pathway has been observed, providing ample experimental support for the tumor-promoting function of NF- ,B in various models of cancer. NF- ,B has been associated with the induction of proinflammatory gene expression and has attracted interest as a target for the treatment of inflammatory disease. However, despite much attention being focused on the deleterious effects of NF- ,B, activation of this factor during the resolution of inflammation is associated with the production of antiinflammatory molecules like interleukin (IL)-10 and the onset of apoptosis. This suggests that NF- ,B has an antiinflammatory role in vivo involving the regulation of the resolution of inflammation. Also, NF- ,B promotes liver regeneration by upregulating IL-6 and other molecules like hepatocyte growth factor. It has been postulated that the beneficial properties of NF- ,B are due to p50 homodimers, whose activation prevents cholestatic and chronic liver injury. More basic understanding on the function of the diverse NF- ,B factors is urgently needed in different physiological and pathological conditions, because depending on the subunit composition of the dimmer, the disease and the stage of the illness, inhibition of the factor may result in a beneficial or in a deleterious response. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Monophasic Action Potential Recordings in Humans

Bridging basic and clinical electrophysiology has been facilitated by monophasic action potential recordings. The electrocardiogram is a useful clinical approach in detecting abnormal repolarization, but falls short in depicting local repolarization details. The MAP waveform is a reflection of local transmembrane action potentials. We hope to convey a basic understanding of monophasic action potential recording and highlight the clinical utility in both ventricular and atrial arrhythmias. [source]

Understanding immune cell trafficking patterns via in vivo bioluminescence imaging

Stefanie Mandl
Abstract Cell migration is a key aspect of the development of the immune system and mediating an immune response. There is extensive and continual redistribution of cells to different anatomic sites throughout the body. These trafficking patterns control immune function, tissue regeneration, and host responses to insult. The ability to monitor the fate and function of cells, therefore, is imperative to both understanding the role of specific cells in disease processes and to devising rational therapeutic strategies. Determining the fate of immune cells and understanding the functional changes associated with migration and proliferation require effective means of obtaining in vivo measurements in the context of intact organ systems. A variety of imaging methods are available to provide structural information, such as X-ray CT and MRI, but only recently new tools have been developed that reveal cellular and molecular changes as they occur within living animals. We have pioneered one of these techniques that is based on the observations that light passes through mammalian tissues, and that luciferases can serve as internal biological sources of light in the living body. This method, called in vivo bioluminescence imaging, is a rapid and noninvasive functional imaging method that employs light-emitting reporters and external photon detection to follow biological processes in living animals in real time. This imaging strategy enables the studies of trafficking patterns for a variety of cell types in live animal models of human biology and disease. Using this approach we have elucidated the spatiotemporal trafficking patterns of lymphocytes within the body. In models of autoimmune disease we have used the migration of "pathogenic" immune cells to diseased tissues as a means to locally deliver and express therapeutic proteins. Similarly, we have determined the tempo of NK-T cell migration to neoplastic lesions and measured their life span in vivo. Using bioluminescence imaging individual groups of animals can be followed over time significantly reducing the number of animals per experiment, and improving the statistical significance of a study since changes in a given population can be studied over time. Such rapid assays that reveal cell fates in vivo will increase our basic understanding of the molecular signals that control these migratory pathways and will substantially speed up the development and evaluation of therapies. J. Cell. Biochem. Suppl. 39: 239,248, 2002. © 2002 Wiley-Liss, Inc. [source]

Deposition and taphonomy of earthworm granules in relation to their interpretative potential in Quaternary stratigraphy,

M. G. Canti
Calcium carbonate granules up to 2.5,mm in size are commonly found in Quaternary soils and sediments but have only rarely been used for any form of interpretation. Growing interest in recent years has focused on the concentration patterns in stratigraphy containing buried land surfaces, and the possibility of dating the granules. Making sense of either of these approaches requires a basic understanding of granule types, together with their modes of accumulation and destruction in stratigraphy. Details of the formation, morphology, deposition and post-depositional changes are discussed along with the necessary ecological and pedological information on earthworm behaviour and effects, then summarised into a framework for interpretations. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Integrating the Principles of Evidence-Based Practice Into Clinical Practice

Kathleen A. Klardie RN
Column Editor Comment This series of articles illustrates many considerations relevant to the application of clinical practice guidelines (CPGs). This particular column describes the actions of a nurse practitioner (NP) striving to understand the foundations of recommendations that are based largely on expert opinion. Although application of CPGs does not generally require this degree of investigation, it is essential that providers understand the processes used to interpret the basis of recommendations, including the application of the basic statistical concepts, when making decisions about how recommendations apply to individual patient scenarios. Utilizing evidence-based practice when providing patient care requires a range of skills that allows the NP to locate appropriate research evidence, to develop an understanding of the statistics used in interpreting and reporting research, and to evaluate the effects of interventions on patient outcomes. The application of the key concepts of evidenced-based practice within the primary care setting is explored through a hypothetical patient scenario, which was created as the focal point for three articles that illustrate principles of evidence-based practice. The goal of this series of articles is to provide a basic understanding of evidence-based practice and its application in clinical practice. This article explores the use of interventions selected from CPGs and investigates the potential effects of recommended interventions on patient outcomes. Commonly encountered statistical concepts are reviewed, and examples of their application in interpreting and reporting research are demonstrated. The principles of relative risk, relative risk reduction, absolute risk reduction, and numbers needed to treat are described. This review provides the NP with some basic skills to determine both the quality and usefulness of research. [source]

Math, Science, and Foreign Language: Evidence-Based Accommodation Decision Making at the Postsecondary Level

Nicole S. Ofiesh
Accommodations in postsecondary settings have become commonplace for many students with learning disabilities (LD) who have documented needs. Many of the accommodations professionals recommend for students with LD are based on an analysis of the course demands, the student's functional limitations, and a basic understanding of how the accommodation can facilitate the demonstration or acquisition of knowledge. However, little is known about which accommodations are recommended for math, science, and foreign language courses as well as the effectiveness of those accommodations. Because these content areas pose substantial hurdles for secondary students with LD who may transition to postsecondary settings, a review of the literature was conducted to evaluate current practices in the provision of accommodations to postsecondary students with LD in math, science, and foreign language courses. Findings indicate strong empirical evidence for extended test time for algebra exams and emerging research in changes to foreign language instruction. Recommendations for further research are provided. [source]

Adult-to-adult right hepatic lobe living donor liver transplantation

P. H. Hayashi
Summary Spurred on by the critical shortage of cadaveric livers, adult-to-adult right hepatic lobe living donor liver transplantation has grown rapidly as a therapeutic option for selected patients. In the USA alone, the number of living donor liver transplantations has increased six-fold in the last 4 years. The therapy can be complex, bringing together a variety of disciplines, including transplantation medicine and surgery, hepatology, psychiatry and medical ethics. Moreover, living donor liver transplantation is still defining itself in the adult-to-adult application. Uniform standards, guidelines and long-term outcomes are yet to be determined. Nevertheless, initial success has been remarkable, and a basic understanding of this field is essential to any physician contemplating options for their liver failure patients. This review covers a range of topics, including recipient and donor selection and outcomes, donor risk, controversies and future issues. [source]

Effects of viscosity and surface roughness on gear contact tribological layers

T. C. Jao
Abstract The increasing dependence on more robust additive chemistry to improve gear pitting resistance requires the additive technology development to rely less on a trial-and-error approach and more on a better basic understanding of the influence of additive chemistry on tribological contact layers' physical and chemical changes. The use of secondary neutral mass spectrometry (SNMS) and nanoindenter to analyse tribological contact layers had been carried out by Inacker and co-workers at NMI. They found that the alkyl structure of zinc dithiophosphate (ZDTP) and the type of cation have a profound effect on the thickness and nanohardness of the tribological layer. An extension to that study has been carried out in this investigation, which involves a design experiment of two variables (oil viscosity and surface roughness) while keeping the additive chemistry constant to determine their impact on the tribological layer. The methods used to analyse the tribological layers include SNMS, nanoindenter and SEM coupled with focused ion beam imaging of the rectangular well-shaped cross section. The results in general are in agreement with the findings of Inacker and his co-workers, namely greater micropitting reduces the thickness of the tribological layer and brings closer the depth of nanohardness maximum to the surface. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Mechanical Properties of a Single Electrospun Fiber and Its Structures

Shu-Ying Gu
Abstract Summary: A method to measure the Young's modulus of a single electrospun polyacrylonitrile (PAN) fiber is reported. The Young's modulus can be calculated from the force-displacement curves obtained by the bending of a single fiber attached to an atomic force microscopy (AFM) cantilever. It is suggested that the high modulus of electrospun fibers is caused by the orientation of molecular chains, which is confirmed by wide-angle X-ray diffraction (WAXD) measurements. The communication will provide a basic understanding of the relationship between mechanical properties and structures of electrospun fibers. A PAN fiber was attached to a contact mode cantilever to facilitate the measurement of force-displacement curves and Young's modulus. [source]

Medication-induced mitochondrial damage and disease

John Neustadt
Abstract Since the first mitochondrial dysfunction was described in the 1960s, the medicine has advanced in its understanding the role mitochondria play in health and disease. Damage to mitochondria is now understood to play a role in the pathogenesis of a wide range of seemingly unrelated disorders such as schizophrenia, bipolar disease, dementia, Alzheimer's disease, epilepsy, migraine headaches, strokes, neuropathic pain, Parkinson's disease, ataxia, transient ischemic attack, cardiomyopathy, coronary artery disease, chronic fatigue syndrome, fibromyalgia, retinitis pigmentosa, diabetes, hepatitis C, and primary biliary cirrhosis. Medications have now emerged as a major cause of mitochondrial damage, which may explain many adverse effects. All classes of psychotropic drugs have been documented to damage mitochondria, as have stain medications, analgesics such as acetaminophen, and many others. While targeted nutrient therapies using antioxidants or their prescursors (e. g., N -acetylcysteine) hold promise for improving mitochondrial function, there are large gaps in our knowledge. The most rational approach is to understand the mechanisms underlying mitochondrial damage for specific medications and attempt to counteract their deleterious effects with nutritional therapies. This article reviews our basic understanding of how mitochondria function and how medications damage mitochondria to create their occasionally fatal adverse effects. [source]

Moisture sorption in moulded fibre trays and effect on static compression strength

Gitte Sørensen
Abstract This study provides a basic understanding of moisture sorption in moulded fibre packaging for food at varying environmental temperatures and humidities, and the resultant effects on static compression strength. The Guggenheim,Anderson,de Boer (GAB) model is used successfully to construct moisture sorption isotherms in the range 2,25°C and 33,98% relative humidity (% r.h.) (R2 = 0.949,0.999), in which moisture content varies from 5.4 to 28.3,g/100,g dry fibre. Static compression strength (SCS) is substantially affected by changes in moisture content of moulded fibre and decreases exponentially with increasing moisture content. The results indicate a minor hysteresis effect on static compression strength. For adsorption of moisture, a relative strength measure, % SCS (experimental SCS in kg divided by a standard SCS in kg), is given by % SCS = 13.83 + 166.50,·,e,0.0978,m (m is moisture content). The temperature dependence of moisture adsorption is incorporated in the GAB model by relating GAB coefficients, m0 and C, exponentially to temperature, T. By combining this with the exponential model for % SCS, static compression strength can be predicted directly from the surrounding temperature and humidity. Illustrated in a response surface plot the effects of changes in the surroundings are simple and readily accessible, e.g. for packaging designers and sales people. It is noted that an increase in humidity from 50% r.h. to 95% r.h. at constant temperature results in a drastic reduction in % SCS from 100% to 40%, whereas the temperature effect is typically less than 10% SCS when reducing temperature from 25°C to 2°C. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Anesthetic considerations for the pediatric oncology patient , part 1: a review of antitumor therapy

Abstract The anesthesiologist who cares for children with cancer or for survivors of childhood cancer should possess a basic understanding of cancer treatment. While this is an ever-changing field, a basic knowledge of chemotherapeutic drugs, radiation therapy, and the toxicities of each is necessary to prepare a safe anesthetic plan. Such an understanding also assists the anesthesiologist as the perioperative specialist for these children in consultation with the surgeon and oncologist. This article, which is the first of a three-part review series, will review current principles of cancer therapy and the general mechanisms of toxicity to the child. Although this article is not intended to comprehensively review the fundamentals of chemotherapy and radiation therapy, the consequences of anticancer therapy that impact perioperative care and decision making are presented for the anesthesiologist. [source]

Breaking symmetry in protein dimers: Designs and functions

Jerry H. Brown
Abstract Symmetry, and in particular point group symmetry, is generally the rule for the global arrangement between subunits in homodimeric and other oligomeric proteins. The structures of fragments of tropomyosin and bovine fibrinogen are recently published examples, however, of asymmetric interactions between chemically identical chains. Their departures from strict twofold symmetry are based on simple and generalizable chemical designs, but were not anticipated prior to their structure determinations. The current review aims to improve our understanding of the structural principles and functional consequences of asymmetric interactions in proteins. Here, a survey of >100 diverse homodimers has focused on the structures immediately adjacent to the twofold axis. Five regular frameworks in ,-helical coiled coils and antiparallel ,-sheets accommodate many of the twofold symmetric axes. On the basis of these frameworks, certain sequence motifs can break symmetry in geometrically defined manners. In antiparallel ,-sheets, these asymmetries include register slips between strands of repeating residues and the adoption of different side-chain rotamers to avoid steric clashes of bulky residues. In parallel coiled coils, an axial stagger between the ,-helices is produced by clusters of core alanines. Such simple designs lead to a basic understanding of the functions of diverse proteins. These functions include regulation of muscle contraction by tropomyosin, blood clot formation by fibrin, half-of-site reactivity of caspase-9, and adaptive protein recognition in the matrix metalloproteinase MMP9. Moreover, asymmetry between chemically identical subunits, by producing multiple equally stable conformations, leads to unique dynamic and self-assembly properties. [source]

A Framework for Understanding State Balanced Budget Requirement Systems: Reexamining Distinctive Features and an Operational Definition

Studies of state fiscal and budgetary policies often use balanced budget requirements (BBRs) as explanatory variables. While current measures laid the crucial groundwork for a basic understanding of state BBRs, their lack of comprehensiveness threatens the validity of empirical work. Based on comprehensive legal research, this article offers a framework for analyzing state requirements: each state's BBRs form a coherent system for achieving budget balance through budget cycles; a fully developed BBR system offers a three-line construct against imbalance; and the more complete, developed, and explicit a BBR system is, the more stringent it will be in achieving budgetary balance. [source]

Tutorials in Clinical Research: Part VII.

Part A: General Concepts of Statistical Significance, Understanding Comparative Statistics (Contrast)
Abstract Objectives/Hypothesis The present tutorial is the seventh in a series of Tutorials in Clinical Research. The specific purpose of the tutorial (Part A) and its sequel (Part B) is to introduce and explain three commonly used statistical tools for assessing contrast in the comparison between two groups. Study Design Tutorial. Methods The authors met weekly for 10 months discussing clinical research studies and the applied statistics. The difficulty was not in the material but in the effort to make the report easy to read and as short as possible. Results The tutorial is organized into two parts. Part A, which is the present report, focuses on the fundamental concepts of the null hypothesis and comparative statistical significance. The sequel, Part B, discusses the application of three common statistical indexes of contrast, the ,2, Mann-Whitney U, and Student t tests. Conclusions Assessing the validity of medical studies requires a working knowledge of research design and statistics; obtaining this knowledge need not be beyond the ability of the busy surgeon. The authors have tried to construct an accurate, easy-to-read, easy-to-apply, basic introduction to comparing two groups. The long-term goal of the present tutorial and others in the series is to facilitate basic understanding of clinical research, thereby stimulating reading of some of the numerous well-written research design and statistical texts. This knowledge may then be applied to the continuing educational review of the literature and the systematic prospective analysis of individual practices. [source]

SRTR Program-Specific Reports on Outcomes: A Guide for the New Reader

D. M. Dickinson
Differences in outcomes indeed exist among transplant programs and organ procurement organizations (OPO). A growing set of tools are available from the Scientific Registry of Transplant Recipients (SRTR) to measure and assess these outcomes in the different phases of the transplant process. These tools are not intended to compare two individual programs, rather to help identify programs whose practices may need further scrutiny, to be either avoided, corrected or emulated. To understand which differences in outcomes might be due to underlying differences in populations served and which might be due to differences in treatment, it is important to compare outcomes to ,risk-adjusted' expected values. Further, it is important to recognize and assess the role that random chance may play in these outcomes by considering the p-value or confidence interval of each estimate. We present the reader with a basic explanation of these tools and their interpretation in the context of reading the SRTR Program-Specific Reports. We describe the intended audience of these reports, including patients, monitoring and process improvement bodies, payers and others such as the media. Use of these statistics in a way that reflects a basic understanding of these concepts and their limitations is beneficial for all audiences. [source]

Investigating the effects of crop type, fertility management and crop protection on the activity of beneficial invertebrates in an extensive farm management comparison trial

M.D. Eyre
Abstract The activity of 11 groups of invertebrates, mainly predators and parasites, was investigated in 2005 and 2006 in a plot trial system on a farm in northern England, where the effects of organic and conventional fertility and crop protection management were separated within different crop types. Invertebrate activity was assessed using pitfall traps and suction sampling. Mixed effects models indicated that crop type significantly affected activity in all 11 groups. Crop protection applications had only a limited impact on activity but fertility management had considerable effects in some crops. Most differences were in barley, wheat and grass/clover, with less in vegetable and bean plots. Carabidae, Lycosidae, Staphylinidae, Linyphiidae and Braconidae gave consistent responses to fertility management, with more activity of the first two groups in organic plots and more of the other three in conventional plots. However, Coccinellidae and Ichneumonidae were not consistent in their activity between crops. After the effects of crop type had been partialled out, a constrained ordination showed that the novel combination of organic fertility and conventional crop protection had the most influence on group activity, with the combination of organic fertility and organic crop protection also significant. Maximising the activity of beneficial invertebrates in organic and sustainable farming systems requires a basic understanding of the effects of both crop type and fertility management, as well as crop protection. [source]

Emerging uses of SIP in service provider networks

Guy J. Zenner
The session initiation protocol (SIP) has emerged as a viable protocol for providing numerous services within today's networks. SIP was closely modeled after http to make it an easily extensible protocol that could provide connectivity in new converged Internet protocol (IP) networks. The inherent extensibility of SIP has allowed SIP to be used in many ways not envisioned by its creators. What started as a simple protocol for setting up a media stream between two endpoints has since found numerous seemingly unrelated uses. With many solutions using SIP being proposed and implemented, it is often hard to determine how best to use SIP for a particular solution. The purpose of this paper is to give the reader a framework for categorizing various SIP capabilities through the concept of usage models and to help the reader understand the various ways SIP can be used in both evolutionary and revolutionary ways in real-world networks. This paper assumes the reader has a basic understanding of SIP and its inner workings. © 2003 Lucent Technologies Inc. [source]

Tight junctions, leaky intestines, and pediatric diseases

Z Liu
Abstract Background: Tight junctions (TJs) represent the major barrier within the paracellular pathway between intestinal epithelial cells. Disruption of TJs leads to intestinal hyperpermeability (the so-called "leaky gut") and is implicated in the pathogenesis of several acute and chronic pediatric disease entities that are likely to have their origin during infancy. Aim: This review provides an overview of evidence for the role of TJ breakdown in diseases such as systemic inflammatory response syndrome (SIRS), inflammatory bowel disease, type 1 diabetes, allergies, asthma, and autism. Conclusion: A better basic understanding of this structure might lead to prevention or treatment of these diseases using nutritional or other means. [source]

Multiple Endocrine Neoplasia , Introduction

Abstract. Each multiple endocrine neoplasia (MEN) syndrome expresses striking features of hormone oversecretion from its own characteristic group of tissues. Additional expressions include non-hormonal tumours in each MEN syndrome and selected cancers in some syndromes. The complexity of its stereotyped features results in difficult management issues that often justify cooperation across multiple specialties. MEN syndromes, though rare, have long received intense study as models for more common diseases. The syndromal nature often with a large pedigree has promoted recent discovery of the main gene that differs for each of the six MEN syndromes. Each mutant gene has been introduced into clinical decision-making and into further clarification of tumorigenesis. This mini-symposium is related to the 9th International Workshop on Multiple Endocrine Neoplasia in June 2004; it consists of six manuscripts. They report new developments in clinical practices and in basic understandings about this rapidly advancing field. [source]