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Large Gaps (large + gap)
Selected AbstractsPaying the piper: a study of musicians and the music businessINTERNATIONAL JOURNAL OF NONPROFIT & VOLUNTARY SECTOR MARKETING, Issue 4 2005Krzysztof Kubacki Many artists argue that treating music as a business represents a particularly insidious force in cultural life, stifling creativity and change. For them business and art are mutually incompatible and they regard the evident economic success of the music industry as an example of the shameless exploitation of our cultural heritage. This paper is based on detailed research into the attitudes of musicians across two distinct cultures. It finds strong echoes of the key criticisms of the music business which have been prominent in academic literature and in the specialist music press for more than a generation. Singled out for particular censure are not-for-profit organisations for apparently following the global recording companies down the same, profit-driven routes. The research confirms that there is a large gap between the expectations of artists and the organisations which employ them and fund their work. It is important that these expectations are understood and, if possible, bridged. For the arts to regain their place at the heart of cultural life it is necessary once more to bring the artists themselves into the picture. Copyright © 2005 John Wiley & Sons, Ltd. [source] Anatomy of a crisis: the causes and consequences of surging food pricesAGRICULTURAL ECONOMICS, Issue 2008Derek Headey Agricultural policy; Commodity markets; Biofuels Abstract Although the potential causes and consequences of recent rising international food prices have attracted widespread attention, many existing appraisals are superficial and/or piecemeal. This article attempts to provide a more comprehensive review of these issues based on the best and most recent research, as well as on fresh theoretical and empirical analysis. We first analyze the causes of the current crisis by considering how well standard explanations hold up against relevant economic theory and important stylized facts. Some explanations turn out to hold up much better than others, especially rising oil prices, the depreciation of the U.S. dollar, biofuels demand, and some commodity-specific explanations. We then provide an appraisal of the likely macro- and microeconomic impacts of the crisis on developing countries. We observe a large gap between macro and micro factors, which, when identifying the most vulnerable countries, often point in different directions. We conclude with a brief discussion of what ought to be learned from this crisis. [source] The prevalence of and risk factors for back pain among home care nursing personnel in Hong Kong,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 1 2006Kin Cheung RN Abstract Background There is a large gap in research with regard to back pain (BP) among home care nursing personnel (HCNP); only seven studies have been conducted worldwide. There is a need to identify the magnitude of and risk factors for BP that are unique to Hong Kong (HK) HCNP. Methods A total population sampling technique was employed in this cross-sectional questionnaire-based study. Hierarchical multiple logistic regression analyses were used to control for potentially confounding variables. Results The 12-month prevalence of upper and lower BP was 71.2% (n,=,265). Three predictors were identified: physical risk factors in the office (OR,=,3.57, 95% CI,=,1.55,8.24), static postures (OR,=,1.41, 95% CI,=,1.04,1.90), and psychological job demands (OR,=,1.11, 95% CI,=,1.01,1.22). Conclusion HCNP in HK have a high prevalence of BP. BP in HK HCNP is independently attributable to physical work factors in the office, static postures, and psychological job demands, and is not primarily associated with patient lifting and transferring which are traditionally identified as risk factors for BP in hospital nursing personnel. Am. J. Ind. Med. 49:14,22, 2006. © 2005 Wiley-Liss, Inc. [source] Analysts' Perceptions of Intellectual Capital InformationAUSTRALIAN ACCOUNTING REVIEW, Issue 3 2010Shigeki Sakakibara This study is based on a survey of 324 financial analysts in Japan. The survey concerns analysts' perceptions of intellectual capital (IC) information and its links to the evaluation of companies. The value relevance of and the access to IC-related information reveals a large gap on many items. The analysis further shows that the lack of access to information hampers analysts' use of IC in their evaluation of companies, particularly in their use of human capital measures. Attitudes towards more disclosure and standardisation are mainly driven by perceptions of what generates value in companies. [source] Staying alive: Dalmatian mediated blocking of apoptosis is essential for tissue maintenanceDEVELOPMENTAL DYNAMICS, Issue 6 2010Bilal E. Kerman Abstract In an EMS screen for mutations disrupting tracheal development, we identified new alleles of the dalmation (dmt) gene, which had previously been shown to affect peripheral nervous system (PNS) development. Here, we demonstrate that dmt loss results in programmed cell death, disrupting PNS patterning and leading to large gaps in the salivary duct and trachea. Dmt loss results in increased expression of the proapoptotic regulator genes head involution defective (hid) and reaper (rpr), and deletion of these genes or tissue-specific expression of the baculoviral apoptotic inhibitor P35 rescues the dmt defects. dmt is also required to protect cells from irradiation induced expression of hid and rpr during the irradiation resistant stage, which begins as cells become irreversibly committed to their final fates. Thus, we propose that Dmt keeps cells alive by blocking activation of hid and rpr as cells become irreversibly committed. Developmental Dynamics 239:1609,1621, 2010. © 2010 Wiley-Liss, Inc. [source] An automated in situ hybridization screen in the medaka to identify unknown neural genesDEVELOPMENTAL DYNAMICS, Issue 3 2005Carole Deyts Abstract Despite the fact that a large body of factors that play important roles in development are known, there are still large gaps in understanding the genetic pathways that govern these processes. To find previously unknown genes that are expressed during embryonic development, we optimized and performed an automated whole-mount in situ hybridization screen on medaka embryos at the end of somitogenesis. Partial cDNA sequences were compared against public databases and identified according to similarities found to other genes and gene products. Among 321 isolated genes showing specific expression in the central nervous system in at least one of five stages of development, 55.14% represented genes whose functions are already documented (in fish or other model organisms). Additionally, 16.51% were identified as conserved unknown genes or genes with unknown function. We provide new data on eight of these genes that presented a restricted expression pattern that allowed for formulating testable hypotheses on their developmental roles, and that were homologous to mammalian molecules of unknown function. Thus, gene expression screening in medaka is an efficient tool for isolating new regulators of embryonic development, and can complement genome-sequencing projects that are producing a high number of genes without ascribed functions. Developmental Dynamics 234:698,708, 2005. © 2005 Wiley-Liss, Inc. [source] PURGING THE GENOME WITH SEXUAL SELECTION: REDUCING MUTATION LOAD THROUGH SELECTION ON MALESEVOLUTION, Issue 3 2009Michael C. Whitlock Healthy males are likely to have higher mating success than unhealthy males because of differential expression of condition-dependent traits such as mate searching intensity, fighting ability, display vigor, and some types of exaggerated morphological characters. We therefore expect that most new mutations that are deleterious for overall fitness may also be deleterious for male mating success. From this perspective, sexual selection is not limited to influencing those genes directly involved in exaggerated morphological traits but rather affects most, if not all, genes in the genome. If true, sexual selection can be an important force acting to reduce the frequency of deleterious mutations and, as a result, mutation load. We review the literature and find various forms of indirect evidence that sexual selection helps to eliminate deleterious mutations. However, direct evidence is scant, and there are almost no data available to address a key issue: is selection in males stronger than selection in females? In addition, the total effect of sexual selection on mutation load is complicated by possible increases in mutation rate that may be attributable to sexual selection. Finally, sexual selection affects population fitness not only through mutation load but also through sexual conflict, making it difficult to empirically measure how sexual selection affects load. Several lines of enquiry are suggested to better fill large gaps in our understanding of sexual selection and its effect on genetic load. [source] Feeding signals to the hungry mindEXPERIMENTAL PHYSIOLOGY, Issue 8 2009Nina Balthasar Obesity, due to its associated co-morbidities, including type 2 diabetes and cardiovascular disease, is at the forefront of today's health care concerns. Our need for novel, multifaceted approaches to tackle the global increase of waistlines is urgent, and understanding the physiological processes underlying our vulnerability to weight gain is an important one of them. Evidence for considerable heritability of body weight indicates genetic influences in the susceptibility to our obesogenic environment. Here, we will focus on neurons in brain structures such as the hypothalamus, which sense the body's metabolic state and, through an intricate cascade of events, elicit an appropriate response. We will explore the use of genetically modified mouse models in the investigation of physiological functions of genes and pathways in neuronal regulation of metabolic balance. Use of these techniques allows us to make manipulations at the molecular level (e.g. in the neuronal metabolic sensing mechanism) and combine this with systems-level physiological analysis (e.g. body weight). Recent technological advances also enable the investigation of the contributions of genes to the co-morbidities of obesity, such as obesity-induced hypertension. Reviewing examples of improvements as well as large gaps in our knowledge, this lecture aims to incite interest in whole body physiological research. [source] Hunting for large carnivore conservationJOURNAL OF APPLIED ECOLOGY, Issue 6 2009Adrian Treves Summary 1. Carnivores are difficult to conserve because of direct and indirect competition with people. Public hunts are increasingly proposed to support carnivore conservation. This article reviews scientific evidence for the effectiveness of public hunts of large carnivores in attaining three common policy goals: stable carnivore populations, preventing conflict with carnivores (property damage and competition over game) and building public support for carnivore conservation. 2. Sustainable exploitation of stable wildlife populations has a solid, scientific foundation but the theory and its predictions must be adapted to complex patterns of carnivore behavioural ecology and population dynamics that demand years of landscape-level monitoring to understand fully. 3. A review of the evidence that hunting prevents property damage or reduces competition for game reveals large gaps in our understanding. Reducing the number of large carnivores to protect hunters' quarry species seems straightforward but we still know little about behavioural and ecological responses of the contested prey and sympatric meso-predators. For reducing property damage, the direct effect , numerical reduction in problematic individual carnivores , presents numerous obstacles, whereas the indirect effect , behavioural avoidance of humans by hunted carnivores , holds more promise. 4. Scientific measures of public support for carnivore-hunting policies are almost completely lacking, particularly measures of attitudes among hunters before and after controversial wildlife is designated as legal game species. Moreover, illegal killing of carnivores does not appear to diminish if they are designated as game. 5.Synthesis and applications. Sustainable hunting to maintain stable populations is well understood in theory but complex life histories of carnivores, and behavioural changes of hunters and the carnivores they stalk may result in unsustainable mortality for carnivores. The direct impact of hunting on carnivore damage to property is unclear and even doubtful given the inability or unwillingness of hunters to remove specific individuals selectively. However, hunters may indirectly deter carnivores from people and their property. The assumption that hunters will steward carnivores simply because they have in the past helped conserve other game species requires more study as preliminary results suggest it is incorrect. Policy-makers may achieve support for policy if they mesh utilitarian and preservationist values held by the general public. A number of opposed hypotheses should be disentangled before researchers confidently inform policy on sustainable hunting to prevent conflicts and build public support for carnivore conservation. [source] Disturbance dynamics of old-growth Picea rubens forests of northern MaineJOURNAL OF VEGETATION SCIENCE, Issue 5 2005Shawn Fraver Abstract Question: How have the spatial and temporal aspects of past disturbance shaped the current structure and composition of old-growth Picea rubens forests? Location: Northern Maine, USA. Methods: We established three 50 m × 50 m plots in old-growth Picea rubens forests and mapped the location of trees and saplings. We extracted increment cores from canopy trees, and recorded growth releases indicating past disturbance. By linking spatial data (tree positions) and temporal data (dated growth releases), we reconstructed the location and size of former canopy gaps back to 1920, and determined a more general disturbance chronology extending as far back as 1740. Results: We found no evidence of stand-replacing disturbances. The disturbance dynamic includes pulses of moderate-severity disturbances caused by wind storms and host-specific disturbance agents (spruce budworm, spruce bark beetle) interposed upon a background of scattered smaller canopy gaps. Consequently, rates of disturbance fluctuated considerably over time. Reconstructed canopy gaps were temporally and spatially scattered; during disturbance peaks, they were both larger and more numerous. Conclusions: Despite peaks in disturbance, several of which created relatively large gaps, this system has experienced no significant change in species composition. Instead, the shade-tolerant Picea rubens has maintained canopy dominance. The patch dynamics described here consist of dramatic structural, not compositional, changes to the forest. The persistence of Picea rubens is attributed to a combination of traits: (1) abundance of advance regeneration; (2) ability to endure suppression and respond favourably to release; and (3) longevity relative to ecologically similar species. [source] History and evolution of the arctic flora: in the footsteps of Eric HulténMOLECULAR ECOLOGY, Issue 2 2003Richard J. Abbott Abstract A major contribution to our initial understanding of the origin, history and biogeography of the present-day arctic flora was made by Eric Hultén in his landmark book Outline of the History of Arctic and Boreal Biota during the Quarternary Period, published in 1937. Here we review recent molecular and fossil evidence that has tested some of Hultén's proposals. There is now excellent fossil, molecular and phytogeographical evidence to support Hultén's proposal that Beringia was a major northern refugium for arctic plants throughout the Quaternary. In contrast, most molecular evidence fails to support his proposal that contemporary east and west Atlantic populations of circumarctic and amphi-Atlantic species have been separated throughout the Quaternary. In fact, populations of these species from opposite sides of the Atlantic are normally genetically very similar, thus the North Atlantic does not appear to have been a strong barrier to their dispersal during the Quaternary. Hultén made no detailed proposals on mechanisms of speciation in the Arctic; however, molecular studies have confirmed that many arctic plants are allopolyploid, and some of them most probably originated during the Holocene. Recurrent formation of polyploids from differentiated diploid or more low-ploid populations provides one explanation for the intriguing taxonomic complexity of the arctic flora, also noted by Hultén. In addition, population fragmentation during glacial periods may have lead to the formation of new sibling species at the diploid level. Despite the progress made since Hultén wrote his book, there remain large gaps in our knowledge of the history of the arctic flora, especially about the origins of the founding stocks of this flora which first appeared in the Arctic at the end of the Pliocene (approximately 3 Ma). Comprehensive analyses of the molecular phylogeography of arctic taxa and their relatives together with detailed fossil studies are required to fill these gaps. [source] Medication-induced mitochondrial damage and diseaseMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 7 2008John 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] The Monitor project: rotation periods of low-mass stars in M50MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2009Jonathan Irwin ABSTRACT We report on the results of a time-series photometric survey of M50 (NGC 2323), a ,130 Myr open cluster, carried out using the Cerro Tololo Inter-American Observatory (CTIO) 4-m Blanco telescope and Mosaic-II detector as part of the Monitor project. Rotation periods were derived for 812 candidate cluster members over the mass range 0.2 ,M/M,, 1.1. The rotation period distributions show a clear mass-dependent morphology, statistically indistinguishable from those in NGC 2516 and M35 taken from the literature. Due to the availability of data from three observing runs separated by ,10 and 1 month time-scales, we are able to demonstrate clear evidence for evolution of the photometric amplitudes, and hence spot patterns, over the 10 month gap. We are not able to constrain the time-scales for these effects in detail due to limitations imposed by the large gaps in our sampling, which also prevent the use of the phase information. [source] Integration of AFLP markers into an RFLP-based map of durum wheatPLANT BREEDING, Issue 5 2000C. Lotti Abstract Amplified fragment length polymorphism (AFLP) is a powerful technique which can readily be applied to a wide range of species for mapping purposes. AFLPs were added to a linkage map of durum wheat constructed using restriction fragment length polymorphisms (RFLPs). The mapping population included 65 recombinant inbred lines derived from a cross between the durum wheat cultivar ,Messapia' and accession ,MG4343' of the wild Triticum turgidum ssp. dicoccoides (Körn.). Genomic DNA was digested with MseI (4-cutter) and Sse83871 (8-cutter). Using a silver-staining protocol, 14 primer combinations revealed 421 clearly scorable amplicons including 100 polymorphisms. The presence of nine pairs of bands linked in repulsion phase with each pair generated by one primer combination suggested the presence of codominant alleles; sequence analysis of four band pairs confirmed their codominant nature. The integration of 80 AFLP loci extended the map in several telomeric regions, reduced the size of four large gaps present in the previous map, and eliminated one gap. The new map obtained after the inclusion of the 80 AFLP loci and eight additional RFLP loci spans 2063cM which represent a 52.6% increment compared with the previous map. Compared with the distribution of RFLPs, no significant clustering of AFLP markers was observed. [source] Acclimation of tropical tree seedlings to excessive light in simulated tree-fall gapsPLANT CELL & ENVIRONMENT, Issue 12 2001G. H. Krause Abstract Acclimation to periodic high-light stress was studied in tree seedlings from a neotropical forest. Seedlings of several pioneer and late-succession species were cultivated under simulated tree-fall gap conditions; they were placed under frames covered with shade cloth with apertures of different widths that permitted defined periods of daily leaf exposure to direct sunlight. During direct sun exposure, all plants exhibited a marked reversible decline in potential photosystem II (PSII) efficiency, determined by means of the ratio of variable to maximum Chl a fluorescence (Fv/Fm). The decline in Fv/Fm under full sunlight was much stronger in late-succession than in pioneer species. For each gap size, all species exhibited a similar degree of de-epoxidation of violaxanthin in direct sunlight and similar pool sizes of xanthophyll cycle pigments. Pool sizes increased with increasing gap size. Pioneer plants possessed high levels of , -carotene that also increased with gap size, whereas , -carotene decreased. In contrast to late-succession plants, pioneer plants were capable of adjusting their Chl a/b ratio to a high value in wide gaps. The content of extractable UV-B-absorbing compounds was highest in the plants acclimated to large gaps and did not depend on the successional status of the plants. The results demonstrate a better performance of pioneer species under high-light conditions as compared with late-succession plants, manifested by reduced photoinhibition of PSII in pioneer species. This was not related to increased pool size and turnover of xanthophyll cycle pigments, nor to higher contents of UV-B-absorbing substances. High , -carotene levels and increased Chl a/b ratios, i.e. reduced size of the Chl a and b binding antennae, may contribute to photoprotection in pioneer species. [source] High-resolution chromosome mapping of BACs using multi-colour FISH and pooled-BAC FISH as a backbone for sequencing tomato chromosome 6THE PLANT JOURNAL, Issue 4 2008Dóra Szinay Summary Within the framework of the International Solanaceae Genome Project, the genome of tomato (Solanum lycopersicum) is currently being sequenced. We follow a ,BAC-by-BAC' approach that aims to deliver high-quality sequences of the euchromatin part of the tomato genome. BACs are selected from various libraries of the tomato genome on the basis of markers from the F2.2000 linkage map. Prior to sequencing, we validated the precise physical location of the selected BACs on the chromosomes by five-colour high-resolution fluorescent in situ hybridization (FISH) mapping. This paper describes the strategies and results of cytogenetic mapping for chromosome 6 using 75 seed BACs for FISH on pachytene complements. The cytogenetic map obtained showed discrepancies between the actual chromosomal positions of these BACs and their markers on the linkage group. These discrepancies were most notable in the pericentromere heterochromatin, thus confirming previously described suppression of cross-over recombination in that region. In a so called pooled-BAC FISH, we hybridized all seed BACs simultaneously and found a few large gaps in the euchromatin parts of the long arm that are still devoid of seed BACs and are too large for coverage by expanding BAC contigs. Combining FISH with pooled BACs and newly recruited seed BACs will thus aid in efficient targeting of novel seed BACs into these areas. Finally, we established the occurrence of repetitive DNA in heterochromatin/euchromatin borders by combining BAC FISH with hybridization of a labelled repetitive DNA fraction (Cot-100). This strategy provides an excellent means to establish the borders between euchromatin and heterochromatin in this chromosome. [source] Mental Health and Emergency Medicine: A Research AgendaACADEMIC EMERGENCY MEDICINE, Issue 11 2009Gregory Luke Larkin MD Abstract The burden of mental illness is profound and growing. Coupled with large gaps in extant psychiatric services, this mental health burden has often forced emergency departments (EDs) to become the de facto primary and acute care provider of mental health care in the United States. An expanded emergency medical and mental health research agenda is required to meet the need for improved education, screening, surveillance, and ED-initiated interventions for mental health problems. As an increasing fraction of undiagnosed and untreated psychiatric patients passes through the revolving doors of U.S. EDs, the opportunities for improving the art and science of acute mental health care have never been greater. These opportunities span macroepidemiologic surveillance research to intervention studies with individual patients. Feasible screening, intervention, and referral programs for mental health patients presenting to general EDs are needed. Additional research is needed to improve the quality of care, including the attitudes, abilities, interests, and virtues of ED providers. Research that optimizes provider education and training can help academic settings validate psychosocial issues as core components and responsibilities of emergency medicine. Transdisciplinary research with federal partners and investigators in neuropsychiatry and related fields can improve the mechanistic understanding of acute mental health problems. To have lasting impact, however, advances in ED mental health care must be translated into real-world policies and sustainable program enhancements to assure the uptake of best practices for ED screening, treatment, and management of mental disorders and psychosocial problems. [source] Application of graph theory to detect disconnected structures in a crystallographic database: copper oxide perovskites as a case studyACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2000Yuri Kotliarov Every crystal structure can be described as a graph with atoms as vertices and bonds as edges. Although such a graph loses the space arrangement of atoms and symmetry elements, it can mathematically represent the connectivity between atoms. This topological approach was used to develop a new method for detecting disconnected structures, in which individual atoms or structural fragments are located too far from each other, forming impossibly large gaps. Approximately 2300 perovskite-related crystal structures have been extracted from the Inorganic Crystal Structure Database (in 1999) and the maximum disconnecting distances, and the relations between them and the ionic radii of elements, have been analysed. Several disconnected structures, which are erroneous by our definition, have been revealed. Conventional tests for crystallographic data checking did not detect those entries. [source] Prebiotics in aquaculture: a reviewAQUACULTURE NUTRITION, Issue 2 2010E. RINGŘ Abstract A prebiotic is a non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or the activity of one or a limited number of bacteria in the colon. Despite the potential benefits to health and performance as noted in various terrestrial animals, the use of prebiotics in the farming of fish and shellfish has been less investigated. The studies of prebiotics in fish and shellfish have investigated the following parameters: effect on growth, feed conversion, gut microbiota, cell damage/morphology, resistance against pathogenic bacteria and innate immune parameters such as alternative complement activity (ACH50), lysozyme activity, natural haemagglutination activity, respiratory burst, superoxide dismutase activity and phagocytic activity. This review discusses the results from these studies and the methods used. If the use of prebiotics leads to health responses becoming more clearly manifested in fish and shellfish, then prebiotics might have the potential to increase the efficiency and sustainability of aquaculture production. However, large gaps of knowledge exist. To fully conclude on the effects of adding prebiotics in fish diets, more research efforts are needed to provide the aquaculture industry, the scientific community, the regulatory bodies and the general public with the necessary information and tools. [source] A Passive Magnetically and Hydrodynamically Suspended Rotary Blood PumpARTIFICIAL ORGANS, Issue 3 2009Martin Stoiber Abstract A combined hydrodynamic,magnetic bearing allows the design of rotary blood pumps that are not encumbered with mechanical bearings and magnets requiring sensors or electrical power. However, such pumps have so far needed very small and accurately manufactured gaps between rotor and housing to assure effective hydromagnetic bearing behavior. In order to use this concept in disposable pump heads, a design that allows larger rotor-housing gaps, and thus larger manufacturing tolerances, is needed. A pump with passive magnetic bearings and a gap between rotor and housing in the range of 0.5 mm was designed. Numerical simulations were performed to optimize the rotor geometry at low levels of shear stress. An experimental test stand was used to find a range of speeds and gap settings that resulted in low levels of vibration and useful pressure,flow relationships. Three different rotor geometries were tested using a viscosity-adjusted test fluid. Blood damage tests were conducted within the desirable range of speeds and gap settings. In this study stable pump performance was demonstrated at total gap widths between 0.3 and 0.7 mm at flows of 0,10 L/min, with afterloads up to 230 mm Hg. Best performance was achieved with rotors sliding on a fluid pillow between the rotor and the outer housing at a gap distance of 50 to 250 µm. The inner gap distance, between the rotor and the inner housing, could be as great as 500 µm. Hemolysis tests on the prototype within the chosen operating range showed lower values (NIH = 0.0029 ± 0.0012 g/100 L) than the Biomedicus BP-80 pump (NIH = 0.0033 ± 0.0011 g/100 L). In conclusion, it is possible to build rotary blood pumps with passive hydromagnetic bearings that have large gaps between their rotors and housings. Rotor behavior is sensitive to the position of the permanent magnetic drive unit. To minimize vibration and blood damage, the fluid gaps and the rotational speed have to be adjusted according to the desired operating point of the pump. Further study is needed to optimize the magnetic drive unit and to ascertain its ability to withstand inertial loads imposed by sudden movements and external shock. [source] Ordered and chaotic spiral armsASTRONOMISCHE NACHRICHTEN, Issue 9-10 2008P.A. Patsis Abstract The stellar flow at the arms of spiral galaxies is qualitatively different among different morphological types. The stars that reinforce the spiral arms can be either participating in an ordered or in a chaotic flow. Ordered flows are associated with normal (non-barred) spiral galaxies. Typically they are described with precessing ellipses corresponding to stable periodic orbits at successive energies (Jacobi constants). On the contrary, the spiral arms in barred-spiral systems may be supported by stars in chaotic motion. The trajectories of these stars are associated with the invariant manifolds of the unstable Lagrangian points (L1,2). Response and orbital models indicate that this kind of spirals either stop at an azimuth smaller than , /2, or present large gaps at about this angle. Chaotic spirals appear in strong bars having (L1,2) close to the ends of the bar. The arms of barred-spiral systems with corotation away from the end of the bar can be either as in the case of normal spirals, or supported by banana-like orbits surrounding the stable Lagrangian points (L4,5). We find also models combining ordered and chaotic flows. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Business Ethics and Business History: Neglected Dimensions in Management EducationBRITISH JOURNAL OF MANAGEMENT, Issue 3 2002R. Warren This article highlights two large gaps in the business school curriculum: the neglect of historical and ethical dimensions. An overview is provided of progress made so far in the UK in the evolution of business history as an academic discipline; and also of the take,up of business ethics in university teaching. Both have had some success, but overall the response to these areas has been somewhat lacklustre , at least in the UK. A justification is provided for adding both components to a fully relevant business education. When the two are combined, the result can be a highly rewarding combination that provides insights that may not be possible for management writers, who work only in the present. Corporate ethics, the social responsibility of companies, disclosure, the environment, the actions of multinational companies overseas, the dilemmas of whistle,blowing, the impact of lobby groups and health and safety issues can all be understood more fully by students if they approach these subjects from an ethical and historical standpoint. [source] | ||||||||||||||||||||||