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Selected AbstractsScreen for expanded FMR1 alleles in patients with essential tremorMOVEMENT DISORDERS, Issue 8 2004Dolores Garcia Arocena MS Abstract Fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disorder, was described recently among male carriers of expanded alleles (55,200 CGG repeats; premutation range) of the fragile X mental retardation 1 (FMR1) gene. Major features of the syndrome include intention tremor, gait ataxia, and parkinsonism in men over 50 years of age. This disorder is believed to be relatively common, possibly affecting 1 in 3,000 men over the age of 50 years in the general population. This raises the possibility that some patients presenting with essential tremor (ET) may harbor expanded FMR1 alleles. We screened 81 ET patients (40 males, 41 females) for expanded FMR1 alleles to determine whether ET is associated with such alleles. None of the ET cases had the premutation genotype. CGG repeat sizes ranged from 5 to 47 repeats within this study population, suggesting that expanded FMR1 alleles are uncommon among patients with ET. Screening of movement disorder patients with other clinical features of FXTAS (e.g., ataxia and parkinsonism) may be more likely to yield expanded FMR1 alleles. © 2004 Movement Disorder Society [source] Two Kinds of Creativity , But Which Ones?CREATIVITY AND INNOVATION MANAGEMENT, Issue 3 2004Geir Kaufmann It is argued that Kirton's theory of styles of creativity is conceptually and methodologically unsound. A solution to the conceptual and methodological dilemmas is offered by way of making a clear-cut distinction between novelty on the stimulus and novelty on the response side. This distinction is used as a platform for the development of a new taxonomy of different kinds of creativity and intelligent behaviour. A major feature of this new model is the distinction made between proactive and reactive creativity. The implications of this distinction for opening new avenues for a more differentiated assessment of creativity, as well as for the development of a conceptually firmer and more differentiated platform for developing new practical training programmes in creativity are suggested. [source] A Possible Role for Gap Junctions in Generation of Very Fast EEG Oscillations Preceding the Onset of, and Perhaps Initiating, SeizuresEPILEPSIA, Issue 2 2001Roger D. Traub Summary: ,Purpose: We propose an experimentally and clinically testable hypothesis, concerning the origin of very fast (>,70 Hz) EEG oscillations that sometimes precede the onset of focal seizures. These oscillations are important, as they may play a causal role in the initiation of seizures. Methods: Subdural EEG recordings were obtained from children with focal cortical dysplasias and intractable seizures. Intra- and extracellular recordings were performed in rat hippocampal slices, with induction of population activity, as follows: (a) bath-applied tetramethylamine (an intracellular alkalinizing agent, that opens gap junctions); (b) bath-applied carbachol, a cholinergic agonist; and (c) focal pressure ejection of hypertonic K+ solution. Detailed network simulations were performed, the better to understand the cellular mechanisms underlying oscillations. A major feature of the simulations was inclusion of axon,axon gap junctions between principal neurons, as supported by recent experimental data. Results: Very fast oscillations were found in children before seizure onset, but also superimposed on bursts during the seizure, and on interictal bursts. In slice experiments, very fast oscillations had previously been seen on interictal-like bursts; we now show such oscillations before, between, and after epileptiform bursts. Very fast oscillations were also seen superimposed on gamma (30,70 Hz) oscillations induced by carbachol or hypertonic K+, and in the latter case, very fast oscillations became continuous when chemical synapses were blocked. Simulations replicate these data, when axonal gap junctions are included. Conclusions: Electrical coupling between principal neurons, perhaps via axonal gap junctions, could underlie very fast population oscillations, in seizure-prone brain, but possibly also in normal brain. The anticonvulsant potential of gap-junction blockers such as carbenoxolone, now in clinical use for treatment of ulcer disease, should be considered. [source] IL-23 promotes osteoclast formation by up-regulation of receptor activator of NF-,B (RANK) expression in myeloid precursor cellsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 10 2008Li Chen Abstract Inflammation-mediated bone loss is a major feature of various bone diseases including rheumatoid arthritis, osteoarthritis and advanced periodontitis. Enhanced osteoclast development or activity at the inflammation site results in bone resorption. IL-23 is a heterodimeric cytokine belonging to the IL-6/IL-12 family that has been implicated in the pathogenesis of rheumatoid arthritis and demonstrated to play a role in osteoclastogenesis via stimulation of IL-17 production. In this study we investigated whether IL-23 contributes to the regulation of osteoclast differentiation independent of the IL-17 pathway. We show that IL-23 dose-dependently up-regulates receptor activator of NF-,B expression in primary murine bone marrow macrophages and RAW264.7 cells and thereby promotes commitment of myeloid precursor cells to receptor activator of NF-,B ligand-mediated osteoclastic differentiation. However, IL-23 by itself is insufficient to induce osteoclastogenesis. Increased osteoclastic differentiation of cells was associated with enhanced cathepsin K expression and dentine resorption indicating enhanced formation of functional osteoclasts. IL-17 was not detectable in culture supernatants and when added to cultures, did not promote differentiation of RAW264.7 cells. These results demonstrate that IL-23 can act directly on myeloid precursor cells in addition to indirectly stimulating receptor activator of NF-,B ligand production in osteoblasts and explains its potency in driving osteoclast development in inflammation-mediated bone pathology. [source] DYNAMICS OF POLYPLOID FORMATION IN TRAGOPOGON (ASTERACEAE): RECURRENT FORMATION, GENE FLOW, AND POPULATION STRUCTUREEVOLUTION, Issue 7 2010V. Vaughan Symonds Polyploidy is a major feature of angiosperm evolution and diversification. Most polyploid species have formed multiple times, yet we know little about the genetic consequences of recurrent formations. Among the clearest examples of recurrent polyploidy are Tragopogon mirus and T. miscellus (Asteraceae), each of which has formed repeatedly in the last ,80 years from known diploid progenitors in western North America. Here, we apply progenitor-specific microsatellite markers to examine the genetic contributions to each tetraploid species and to assess gene flow among populations of independent formation. These data provide fine-scale resolution of independent origins for both polyploid species. Importantly, multiple origins have resulted in considerable genetic variation within both polyploid species; however, the patterns of variation detected in the polyploids contrast with those observed in extant populations of the diploid progenitors. The genotypes detected in the two polyploid species appear to represent a snapshot of historical population structure in the diploid progenitors, rather than modern diploid genotypes. Our data also indicate a lack of gene flow among polyploid plants of independent origin, even when they co-occur, suggesting potential reproductive barriers among separate lineages in both polyploid species. [source] Migraine: A Chronic Sympathetic Nervous System DisorderHEADACHE, Issue 1 2004Stephen J. Peroutka MD Objective.,To determine the degree of diagnostic and clinical similarity between chronic sympathetic nervous system disorders and migraine. Background.,Migraine is an episodic syndrome consisting of a variety of clinical features that result from dysfunction of the sympathetic nervous system. During headache-free periods, migraineurs have a reduction in sympathetic function compared to nonmigraineurs. Sympathetic nervous system dysfunction is also the major feature of rare neurological disorders such as pure autonomic failure and multiple system atrophy. There are no known reports in the medical literature, however, comparing sympathetic nervous system function in individuals with migraine, pure autonomic failure, and multiple system atrophy. Methods.,A detailed review of the literature was performed to compare the results of a wide variety of diagnostic tests and clinical signs that have been described in these 3 heretofore unrelated disorders. Results.,The data indicate that migraine shares significant diagnostic and clinical features with both pure autonomic failure and multiple system atrophy, yet represents a distinct subtype of chronic sympathetic dysfunction. Migraine is most similar to pure autonomic failure in terms of reduced supine plasma norepinephrine levels, peripheral adrenergic receptor supersensitivity, and clinical symptomatology directly related to sympathetic nervous system dysfunction. The peripheral sympathetic nervous system dysfunction is much more severe in pure autonomic failure than in migraine. Migraine differs from both pure autonomic failure and multiple system atrophy in that migraineurs retain the ability, although suboptimal, to increase plasma norepinephrine levels following physiological stressors. Conclusions.,The major finding of the present study is that migraine is a disorder of chronic sympathetic dysfunction, sharing many diagnostic and clinical characteristics with pure autonomic failure and multiple system atrophy. However, the sympathetic nervous system dysfunction in migraine differs from pure autonomic failure and multiple system atrophy in that occurs in an anatomically intact system. It is proposed that the sympathetic dysfunction in migraine relates to an imbalance of sympathetic co-transmitters. Specifically, it is suggested that a migraine attack is characterized by a relative depletion of sympathetic norepinephrine stores in conjunction with an increase in the release of other sympathetic cotransmitters such as dopamine, prostaglandins, adenosine triphosphate, and adenosine. An enhanced understanding of the sympathetic dysfunction in migraine may help to more effectively diagnose, prevent, and/or treat migraine and other types of headache. [source] Neoplastic development in plasma cellsIMMUNOLOGICAL REVIEWS, Issue 1 2003Michael Potter Summary:, An increasing number of model systems of plasma cell tumor (PCT) formation have been and are being developed. Discussed here are six models in mice and multiple myeloma (MM) in humans. Each model illustrates a unique set of biological factors. There are two general types of model systems: those that depend upon naturally arising mutagenic changes (pristane-induced PCTs, 5TMM, and MM) and those that are associated with oncogenes (Eµ-v-abl), growth factors [interleukin-6 (IL-6)], and anti-apoptotic factors (Bcl-xL/Bcl-2). PCTs develop in several special tissue microenvironments that provide essential cytokines (IL-6) and cell,cell interactions. In mice, the activation and deregulation of c-myc by chromosomal translocations is a major feature in many of the models. This mechanism is much less a factor in MM and the 5T model in mice. Genetically determined susceptibility is involved in many of the mouse models, but only a few genes have been implicated thus far. [source] Aberrant p53 alters DNA damage checkpoints in response to cisplatin: Downregulation of CDK expression and activityINTERNATIONAL JOURNAL OF CANCER, Issue 5 2004Katharine H. Wrighton Abstract The p53 tumor suppressor protein is a critical mediator of cell cycle arrest and apoptosis in response to genotoxic stress. Abrogation of p53 function is a major feature of tumor development and may result in a compromised DNA-damage response. In our study, we examined the effect of expressing a human p53 cDNA, encoding a histidine to leucine amino acid substitution at codon 179 (H179L), on the ability of wild-type p53-containing NIH3T3 cells to respond to treatment with the chemotherapeutic cisplatin. After 72 hr of cisplatin treatment control cells underwent apoptosis preceded by a combination of S- and G2 arrest, as judged by flow cytometry of propidium iodide-stained cells, and TUNEL and caspase-3 assays. This correlated with increased expression of the pro-apoptotic protein Bax. In contrast, cells stably expressing H179L-p53 arrested in S-phase following cisplatin treatment, which correlated with a marked decrease in the expression of cdc2, cyclin B1 and cyclin A, and a decrease in CDK2 and cyclin A-associated kinase activity. Interestingly, H179L p53 expressing cells underwent apoptosis earlier than control cells, indicating that this aberrant p53 may enhance cisplatin chemosensitivity. These data suggest that dominant-negative p53 can influence the expression and activity of CDK complexes, thereby modifying cell behavior following cisplatin-induced genotoxicity. © 2004 Wiley-Liss, Inc. [source] Evaluation of broad scale vertical circulation and thermal indices in relation to the onset of Indian summer monsoonINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2002S. K. Roy Bhowmik Abstract The onset of the Indian summer monsoon over Kerala for an individual year of delayed (1997), early (1999) and normal onset (2000) was examined in relation to the intensity of vertical circulation and thermal indices during the pre-monsoon months (April and May). The study showed that in the delayed monsoon onset year (1997) negative anomalies of vertical zonal index dominated over the north Indian Ocean during pre-monsoon months, particularly in April. In contrast, in the early onset year (1999) the positive anomalies of this index over the north Indian Ocean during the pre-monsoon months were considerably stronger (April and May). However, the meridional vertical index did not show any appreciable difference. The gradient of the vertical thermal index anomalies over the Tibetan Plateau in the month of April was prominently stronger during the years of early and normal onset (1999 and 2000). The anomalies of geopotential height at 200 hPa over the Tibetan Plateau in the pre-monsoon months were significantly lower in the year of delayed onset (1997). The precipitable water content was found to be another major feature, which grew rapidly over the equatorial belt of the Indian Ocean extending up to the Arabian Sea and Bay of Bengal during the two weeks prior to onset. Most of these features were observed very distinctly in the month of April, well before the monsoon onset, and promise to provide important predictive signals for the onset over Kerala. Copyright © 2002 Royal Meteorological Society. [source] Fluid evolution and thermal structure in the rapidly exhuming gneiss complex of Namche Barwa,Gyala Peri, eastern Himalayan syntaxisJOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2005D. CRAW Abstract High-grade gneisses (amphibolite,granulite facies) of the Namche Barwa and Gyala Peri massifs, in the eastern Himalayan syntaxis, have been unroofed from metamorphic depths in the late Tertiary,Recent. Rapid exhumation (2,5 mm year,1) has resulted in a pronounced shallow conductive thermal anomaly beneath the massifs and the intervening Tsangpo gorge. The position of the 300 °C isotherm has been estimated from fluid inclusions using CO2,H2O immiscibility phase equilibria to be between 2.5 and 6.2 km depth below surface. Hence, the near-surface average thermal gradient exceeds 50 °C km,1 beneath valleys, although the thermal gradient is relatively lower beneath the high mountains. The original metamorphic fluid in the gneisses was >90% CO2. This fluid was displaced by incursion of brines from overlying marine sedimentary rocks that have since been largely removed by erosion. Brines can exceed 60 wt% dissolved salts, and include Ca, Na, K and Fe chlorides. These brines were remobilized during the earliest stages of uplift at >500 °C. During exhumation, incursion of abundant topography-driven surface waters resulted in widespread fracture-controlled hydrothermal activity and brine dilution down to the brittle,ductile transition. Boiling water was particularly common at shallow levels (<2.5 km) beneath the Yarlung Tsangpo valley, and numerous hot springs occur at the surface in this valley. Dry steam is not a major feature of the hydrothermal system in the eastern syntaxis (in contrast to the western syntaxis at Nanga Parbat), but some dry steam fluids may have developed locally. [source] An International Imperative for Gender-Sensitive Theories in Women's HealthJOURNAL OF NURSING SCHOLARSHIP, Issue 4 2001Eun-Ok Im Purpose: To propose gender-sensitive theories as a future direction for theoretical development of women's health. Few theories pertain to women's health and illness experiences, with gender issues embedded in social, cultural, and historical contexts. Organizing Construct: Significance, definition, and philosophical bases of gender-sensitive theories. Findings: Six major components should be incorporated in the development of gender-sensitive theories: (a) gender as a major feature, (b) women's own words and experiences, (c) nature of women's experiences, (d) theorists' perspectives, (e) contexts, and (f) guidelines for actions. Conclusions: We believe that the development of gender-sensitive theories in nursing could enable researchers to transcend androcentric and ethnocentric views on women's health, decrease gender inequity in health care, enhance women's well being, and ultimately contribute to knowledge development in nursing. [source] Dissociation: An insufficiently recognized major feature of complex posttraumatic stress disorderJOURNAL OF TRAUMATIC STRESS, Issue 5 2005Onno van der Hart The role of dissociation in (complex) posttraumatic stress disorder (PTSD) has been insufficiently recognized for at least two reasons: the view that dissociation is a peripheral, not a central feature of PTSD, and existing confusion regarding the nature of dissociation. In this conceptual article, the authors address both issues by postulating that traumatization essentially involves some degree of division or dissociation of psychobiological systems that constitute personality. One or more dissociative parts of the personality avoid traumatic memories and perform functions in daily life, while one or more other parts remain fixated in traumatic experiences and defensive actions. Dissociative parts manifest in negative and positive dissociative symptoms that should be distinguished from alterations of consciousness. Complex PTSD involves a more complex structural dissociation than simple PTSD. [source] A gene repertoire for nitrogen transporters in Laccaria bicolorNEW PHYTOLOGIST, Issue 2 2008Eva Lucic Summary ,,Ectomycorrhizal interactions established between the root systems of terrestrial plants and hyphae from soil-borne fungi are the most ecologically widespread plant symbioses. The efficient uptake of a broad range of nitrogen (N) compounds by the fungal symbiont and their further transfer to the host plant is a major feature of this symbiosis. Nevertheless, we far from understand which N form is preferentially transferred and what are the key molecular determinants required for this transfer. ,,Exhaustive in silico analysis of N-compound transporter families were performed within the genome of the ectomycorrhizal model fungus Laccaria bicolor. A broad phylogenetic approach was undertaken for all families and gene regulation was investigated using whole-genome expression arrays. ,,A repertoire of proteins involved in the transport of N compounds in L. bicolor was established that revealed the presence of at least 128 gene models in the genome of L. bicolor. Phylogenetic comparisons with other basidiomycete genomes highlighted the remarkable expansion of some families. Whole-genome expression arrays indicate that 92% of these gene models showed detectable transcript levels. ,,This work represents a major advance in the establishment of a transportome blueprint at a symbiotic interface, which will guide future experiments. [source] IL-4,/, mice with lethal Mesocestoides corti infections , reduced Th2 cytokines and alternatively activated macrophagesPARASITE IMMUNOLOGY, Issue 12 2009A. E. O'CONNELL Summary Protection against Mesocestoides corti, a cestode that invades vital organs, is dependent on the production of IL-4, as IL-4,/, mice were found to have higher parasite burdens when compared with wild-type mice. The goal of this study was to investigate the role of IL-4 in immunity to M. corti, focusing on the immunological profile and on potential mediators of pathology. IL-4,/, mice infected with M. corti showed 100% mortality by 32 days, whereas wild-type mice survived for approximately 1 year. Parasite burdens were significantly increased in the liver, peritoneal, and thoracic cavities of IL-4,/, mice, associated with impaired recruitment of inflammatory cells and a reduction in monocytes and macrophages. IL-5 production by splenocytes and expression in liver tissue was decreased in infected IL-4,/, mice compared with wild-type mice. In contrast, IL-4,/, mice produced increased amounts of IFN, and TNF,. Alternatively activated macrophages were a major feature of liver granulomas in wild-type mice evidenced by Arginase I expression, while livers from infected IL-4,/, mice showed impaired alternative macrophage activation without increased classical macrophage activation. Thus, lethality during M. corti infection of IL-4,/, mice is associated with decreased Th2 cytokines, increased Th1 cytokines and impairment of alternatively activated macrophages. [source] Epigenetic Mechanisms Affecting Macronuclear Development in Paramecium and TetrahymenaTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2000JOHN R. PREER JR. ABSTRACT. Epigenetic inheritance includes all non-Mendelian inheritance, in fact any inheritance that does not arise from base changes. Ciliates, particularly Paramecium and Tetrahymena, undergo epigenetic changes to their macronuclei when they are formed at nuclear reorganization. Once set, however, they are reproduced in a constant fashion, except for allelic segregations, during vegetative fissions in Tetrahymena and certain life cycle changes in both Paramecium and Tetrahymena. This review is meant to be inclusive, discussing all the known cases of epigenetic changes in macronuclei. They involve virtually all traits. We find that these macronuclear changes are subject to a variety of modifications in the way that they are implemented. They constitute a major feature of ciliate genetics, probably because the separation of generative and vegetative functions to micronuclei and macronuclei makes such changes possible. [source] The National Renewable Energy Target: An Example of Post-Machiavellian Policy-Making?AUSTRALIAN JOURNAL OF PUBLIC ADMINISTRATION, Issue 2 2010Stephen Jones Since the election of the Rudd Government in 2007 intergovernmental relations have been a major feature of the political agenda. A ,new federalism' approach introduced a re-invigorated Council of Australian Governments (COAG) focused on developing national policies that reflect coordinated and cooperative policy-making processes. The establishment of COAG working groups provided the means for developing policies that reflect new levels of agreement between jurisdictions and a common approach to reform. The development of the 20% Renewable Energy Target has been one of the first initiatives of this new approach to policy-making. This research analyses the process behind the development of the target and places it within the context of the post-Machiavellian approach, and looks at the implications for future intergovernmental relations. [source] Bayesian Nonparametric Nonproportional Hazards Survival ModelingBIOMETRICS, Issue 3 2009Maria De Iorio Summary We develop a dependent Dirichlet process model for survival analysis data. A major feature of the proposed approach is that there is no necessity for resulting survival curve estimates to satisfy the ubiquitous proportional hazards assumption. An illustration based on a cancer clinical trial is given, where survival probabilities for times early in the study are estimated to be lower for those on a high-dose treatment regimen than for those on the low dose treatment, while the reverse is true for later times, possibly due to the toxic effect of the high dose for those who are not as healthy at the beginning of the study. [source] Simulating the Dynamics of Spouted-Bed Nuclear Fuel Coaters,CHEMICAL VAPOR DEPOSITION, Issue 9 2007S. Pannala Abstract We describe simulation studies of the dynamics of spouted beds used for CVD coating of nuclear fuel particles. Our principal modeling tool is the Multiphase Flow with Interphase eXchanges (MFIX) code that was originally developed by the National Energy Technology Laboratory (NETL) for fossil energy process applications. In addition to standard MFIX features that allow coupling of transient hydrodynamics, heat and mass transfer, and chemical kinetics, we employ special post-processing tools to track particle mixing and circulation as functions of operating conditions and bed design. We describe in detail one major feature of the dynamics, which is the occurrence of very regular spontaneous pulsations of gas and particle flow in the spout. These pulsations appear to be critically linked to the entrainment and circulation of solids, and they produce readily accessible dynamic pressure variations that can be used for direct comparisons of model predictions with experiments. Spouted-bed dynamics are important from a CVD perspective because they directly determine the magnitude and variability of the concentration and species gradients in the zone where reactant gases first come into contact with hot particles. As this unsteady spouted-bed environment differs from other types of CVD reactors, the design and scale-up of such reactors is likely to involve unique modeling issues. Our primary goal here is to lay the groundwork for how computational simulation can be used to address these modeling issues in the specific context of nuclear fuel particle coating. [source] Affect regulation in borderline personality disorder: experimental findings from psychophysiology and functional neuroimagingACTA NEUROPSYCHIATRICA, Issue 2 2002S. C. Herpertz Background: Intense and rapidly changing mood states are a major feature of borderline personality disorder (BPD), which is thought to arise from affective vulnerability. Objective: There have been only a few studies investigating affective processing in BPD, and particularly neither psychophysiological nor neurofunctional correlates of abnormal emotional processing have been identified so far. Methods:, Studies are reported using psychophysiological or functional neuroimaging methodology. Results:, The psychophysiological study did not indicate a general emotional hyperresponsiveness in BPD. Low autonomic arousal seemed to reflect dissociative states in borderline subjects experiencing intense emotions. In the functional magnetic resonance imaging study enhanced amygdala activation was found in BPD, and it is suggested to reflect the intense and slowly subsiding emotions commonly observed in response to even low-level stressors. Conclusions:, Implications for psychotherapy are discussed. [source] Highly conserved gene expression profiles in humans with allergic rhinitis altered by immunotherapyCLINICAL & EXPERIMENTAL ALLERGY, Issue 12 2005Z. Liu Summary Background Atopic diseases, resulting from hypersensitivity to a wide variety of allergens, affect 10,20% of the population. Immunotherapy is an effective treatment for atopic diseases, but its mechanisms are not fully understood. Objective We studied gene expression profiles in the peripheral blood mononuclear cells (PBMC) and examined whether the individuals with allergic rhinitis (AR) have a unique gene expression profile and how the immunotherapy affect the gene expression profiles. Methods We used cDNA microarray and ,expression analysis systemic explorer' to examine the gene expression profiles in the PBMC of atopic subjects and other groups. Results We identified a highly conserved gene expression profile in atopic subjects that permitted their accurate segregation from control or autoimmune subjects. A major feature of this profile was the under-expression of a variety of genes that encode proteins required for apoptosis and over-expression of genes that encode proteins critical for stress responses and signal transduction. We also identified 563 genes that can segregate individuals with AR based upon receipt of immunotherapy. Conclusion There is a highly conserved gene expression profile in the PBMC of individuals with AR. This profile can be used to identify individuals with AR and to evaluate responses to immunotherapy. Quantitative endpoints, such as gene expression, may assist clinicians faced with clinical decisions in the diagnosis of patients and the evaluation of response to therapy. The knowledge of the possible genetic basis for immunotherapy efficacy may also lead to novel therapeutic approaches for atopic diseases. [source] Using particles for 3D texture sculptingCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 4 2001ich Bene Abstract Particle systems have been used in computer graphics for many different purposes, including visual simulation of fur, grass, hair, and similar fuzzy textures and shapes. The underlying theories used in these algorithms are usually quite complex and are mostly based on simulation of diffuse-limited aggregation, cellular development, reaction-diffusion models, etc. This leads to high time complexity of these algorithms. The purpose of this paper is to show that collision detection and distance keeping among moving particles can generate similar realistic textures efficiently. This approach is easy to implement, sufficiently fast allowing for interactive modeling, and inherits the major features from the previously published techniques. We first construct a scene consisting of generators of particles, attractors, and cutters. The generators generate oriented particles, and the attractors attract or repulse them. When collision with the cutter is detected, the particle performs an action according to its state and position in the 3D space. Every particle has assigned a table of possible actions that is used for solving these critical states. Trajectories of the particles are then used as a resulting shape of the texture. Copyright © 2001 John Wiley & Sons, Ltd. [source] A Possibilistic Petri Net Model for Diagnosing Cracks in RC StructuresCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2003Kevin F. R. Liu PPN integrates Petri nets with possibilistic reasoning and maintains the advantages of both formalisms. Two major features of PPN include the possibilistic token to carry information to describe an object and its corresponding possibility and necessity measures, and four types of possibilistic transitions,inference, duplication, aggregation, and aggregation-duplication. A reasoning algorithm, based on possibilistic Petri nets, is also developed to execute PPN. The PPN model and the reasoning algorithm are further used to diagnose possible causes of cracking in RC structures, and three basic cases are considered to demonstrate the applicability of the approach. The reliability of the results is increased by explaining the diagnostic process through the movement of tokens. Moreover, the confidence level associated with each possible cause of concrete cracking can be used to determine the relevance of the diagnosis. [source] Grasshopper (Orthoptera: Acridoidea) species diversity in the Pampas, ArgentinaDIVERSITY AND DISTRIBUTIONS, Issue 2 2000María Marta Cigliano Abstract., A study was conducted to describe the major features of geographical and temporal variation in the diversity of grassland grasshopper species (Orthoptera: Acridoidea) in different sites of the Pampas, Argentina. Species richness and relative abundance were assessed at 12 sites in eastern La Pampa and western Buenos Aires provinces, from 1994 through 1999. Mean species richness at the regional level was 10, and 34 grasshopper species were collected throughout of the study. Comparison with grasshopper species diversity from the Great Plains of North America is discussed. An evaluation of the proportions of species in each of the three distribution groups (broad, intermediate and narrow) revealed that, over all sites, broadly distributed species made up 14.7% of species composition and intermediately and narrowly distributed species made up 26.5% and 58.8%, respectively. The three top-ranked species in the studied sites were Dichroplus elongatus, D. pratensis and Staurorhectus longicornis. Results showed that, contrary to what was expected, one of the widely distributed species in the region (i.e. Baeacris punctulatus) does not always constitute one of the most abundant species. Finally, the loss of one of the historically most common species in the Pampas, D. maculipennis, is also discussed. [source] Large eddy simulations of turbulent swirling flows in a dump combustor: a sensitivity studyINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 2 2005P. Wang Abstract Large eddy simulations (LES) of confined turbulent swirling flows in a model dump combustor are carried out. The simulations are based on a high-order finite difference method on a Cartesian grid, with the sub-grid scale stress tensor modelled using a scale-similarity model. The aims of this work are to study the physics of the flow and to evaluate the performance of LES method for simulation of the major features of turbulent swirling flows,the vortex breakdown, the highly anisotropic and fast-decaying turbulence structure. Influences of inflow/outflow conditions, combustor geometry, inlet swirl profile and Reynolds numbers on the vortex breakdown and turbulence structures are investigated. At very high swirl levels, the influence of the outflow conditions and the outlet geometry is fairly significant, not only at downstream near the outlet, but also at far upstream. At low Reynolds numbers, the onset of vortex breakdown is fairly sensitive to the change of Reynolds number; however, at high Reynolds numbers it is rather insensitive to the Reynolds number. Comparisons of LES results with experimental data are made. The LES results are shown to be in reasonably good agreement with the experimental data if appropriate inflow and outflow boundary conditions are imposed. Copyright © 2004 John Wiley & Sons, Ltd. [source] Motility: mobility as capitalINTERNATIONAL JOURNAL OF URBAN AND REGIONAL RESEARCH, Issue 4 2004Vincent Kaufmann Social and territorial structures form intricate relations that transcend a social stratification or spatial focus. Territorial features and geographic displacements are structuring principles for society, as societal features and social change effect the structure and use of territory. Based on our examination of the conceptual and theoretical links between spatial and social mobility, we propose a concept that represents a new form of inequality. Termed ,motility', this construct describes the potential and actual capacity of goods, information or people to be mobile both geographically and socially. Three major features of motility , access, competence and appropriation , are introduced. In this article, we focus on conceptual and theoretical contributions of motility. In addition, we suggest a number of possible empirical investigations. Motility presents us with an innovative perspective on societal changes without prematurely committing researchers to work within structuralist or postmodern perspectives. More generally, we propose to revisit the fluidification debate in the social sciences with a battery of questions that do not begin and end with whether or not society is in flux. Instead, we introduce a field of research that takes advantage of the insights from competing paradigms in order to reveal the social dynamics and consequences of displacements in geographic and social space. Les structures sociales et territoriales forment des relations complexes qui dépassent toute stratification sociale ou convergence spatiale. Les caractéristiques territoriales et déplacements géographiques sont, pour la société, des principes structurants, tout comme les caractéristiques sociétales et le changement social font naître la structure et l'usage d'un territoire. A partir d'un examen des liens conceptuels et théoriques entre les mobilités spatiale et sociale, cet article propose un concept traduisant une nouvelle forme d'inégalité: appelé,motilité', il décrit le potentiel et l'aptitude réelle des marchandises, informations ou individus àêtre mobiles sur un plan tant géographique que social. Trois traits essentiels de la motilité, accès, compétence et appropriation , sont présentés. Si l'article s'attache aux contributions conceptuelles et théoriques de la motilité, il suggère aussi plusieurs axes possibles d'études empiriques. La motilité offre une perspective novatrice sur les changements sociétaux, sans engager prématurément les travaux de recherches sur des rails structuralistes ou post-modernes. Plus généralement, il s'agit de revisiter le débat sur la fluidification en sciences sociales à l'aide d'une batterie de questions qui, ni au début ni à la fin, ne demande si la société est fluctuante ou non. En revanche, l'article propose un domaine de recherches qui exploite les réflexions tirées de paradigmes concurrents afin de révéler la dynamique sociale et les conséquences des déplacements dans l'espace géographique et social. [source] Food limitation and insect outbreaks: complex dynamics in plant,herbivore modelsJOURNAL OF ANIMAL ECOLOGY, Issue 5 2007KAREN C. ABBOTT Summary 1The population dynamics of many herbivorous insects are characterized by rapid outbreaks, during which the insects severely defoliate their host plants. These outbreaks are separated by periods of low insect density and little defoliation. In many cases, the underlying cause of these outbreaks is unknown. 2Mechanistic models are an important tool for understanding population outbreaks, but existing consumer,resource models predict that severe defoliation should happen much more often than is seen in nature. 3We develop new models to describe the population dynamics of plants and insect herbivores. Our models show that outbreaking insects may be resource-limited without inflicting unrealistic levels of defoliation. 4We tested our models against two different types of field data. The models successfully predict many major features of natural outbreaks. Our results demonstrate that insect outbreaks can be explained by a combination of food limitation in the herbivore and defoliation and intraspecific competition in the host plant. [source] Electrophysiological Basis and Genetics of Brugada SyndromeJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 2005AUGUSTUS O. GRANT M.B.Ch.B., Ph.D. Brugada syndrome is a primary arrhythmic syndrome arising in the structurally normal heart. Any proposed mechanism should account for the major features of the syndrome: localization of the ST segment and T-wave changes to the right precordial leads, association of conduction slowing at several levels, precipitation or aggravation of the major ECG changes by sodium channel-blocking drugs and the occurrence of ventricular fibrillation. Heterogeneity of repolarization across the ventricle wall plays a major role. Any agency that shifts the net current gradient during phase I outward would exaggerate the normal heterogeneity of repolarization and result in the ST segment and T-wave changes characteristic of the syndrome. When the outward current shift is marked, premature repolarization may occur in epicardial zone and the resulting gradient may precipitate reentry. The syndrome is inherited as an autosomal dominant. However, 75% of clinically affected individuals are males. In 20% of cases, the syndrome is associated with mutations of the cardiac sodium channel gene SCN5A. The mutations result in a loss-of-function as a result of the synthesis of a non-functional protein, altered protein trafficking, or change in gating. Agencies that reduce the sodium current may precipitate the characteristic ECG changes, for example, sodium channel blockers and membrane depolarization by hyperkalemia. Sympathetic stimulation may reverse the ECG changes and reduce arrhythmia recurrence. By its nonspecific potassium channel blocking action, quinidine may also reduce arrhythmia recurrence. We still do not know the basis for defect in the majority of patients with Brugada syndrome. [source] A stem-group caecilian (Lissamphibia: Gymnophiona) from the Lower Cretaceous of North AfricaPALAEONTOLOGY, Issue 2 2001Susan E. Evans Of living amphibian groups, the limbless burrowing caecilians are amongst the most highly specialised, but are the least known. Their fossil record is extremely poor, leaving unresolved questions as to their origins, relationships and early distribution. We describe here caecilian remains from a Lower Cretaceous (Berriasian) microfossil locality near Anoual, Morocco. This material represents the second oldest record for the group, after the Jurassic Eocaecilia of North America, and the earliest caecilian record for Gondwana. It forms the basis of a new genus, Rubricacaecilia, which appears slightly more derived than Eocaecilia, but lacks major features of crown-group taxa. We support the use of Apoda Oppel, 1811 for the crown-group alone, and Gymnophiona Rafinesque 1814 for the clade comprising stem-group taxa + Apoda. [source] Riding The Ciliate Cell Cycle,A Thirty-Five-Year Prospective,THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 5 2001JAMES D. BERGER ABSTRACT. Studies of the ciliate cell cycle have moved from early examination of its biochemistry with heat-synchronized Tetra-hymena through descriptive studies of Paramecium using small synchronous cell samples. These studies described what happens during the cell cycle and provided some initial insights into control, especially the idea that there was a point at which cells became committed to division. This early work was followed by an analytical phase in which the same small sample techniques, combined with gene mutations, were used to tease apart some major features of the regulation of cell growth kinetics, including regulation of macronuclear DNA content and regulation of cell size, the control of timing of initiation of macronuclear DNA synthesis, and the control of commitment to division in Paramecium. The availability of new molecular genetic approaches and new means of manipulating cells en masse made it possible to map out some of the basic features of the molecular biology of cell cycle regulation in ciliates. The challenge before us is to move beyond the ,me-too-ism' of validating the presence of basic molecular regulative machinery underlying the cell cycle in ciliates to a deeper analysis of the role of specific molecules in processes unique to ciliates or to analysis of the role of regulatory molecules in the control of cell process that can be uniquely well studied in ciliates. [source] Coriolis effects in mesoscale flows with sharp changes in surface conditionsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 603 2004J. C. R. Hunt Abstract A general linearized ,shallow-layer' perturbation model, where the approximately neutral lower layer of thickness h0 is situated below a stable upper layer (i.e. an inversion with temperature change ,T), is developed for steady, mesoscale atmospheric flows over low-lying topography whose height is less than h0. With the Coriolis parameter f, sharp changes in surface conditions (surface roughness, terrain elevation, heat flux) are modelled as a distributed body force through the lower layer. The Froude number of this layer is small. Typical cases of mesoscale discontinuities are examined. The results are compared with those of a continuously stratified model and observations, and with numerical mesoscale model results for a meteorological case-study over the Dover Straits region of the English Channel. The main results are: (i) If the wind direction is parallel to the edge-line separating the change in surface roughness, there are marked increases and decreases in these coastal winds whose maxima can occur over the sea within a distance of order h0(,1 km) of a coast. The strength of these wind ,jets', which do not occur in the absence of Coriolis force, decrease away from the edge-line gradually over transverse length-scales of the order of the Rossby deformation radius . Changes to surface roughness lead to an increase in the wind speed perturbation in the downwind direction until limited by non-linear effects. When the wind is at an angle to a roughness change or coast, the maxima occur at the coastline. (ii) Where there are sharp changes in the orientation of contours of constant roughness length (e.g. at capes or bays on the coastline or wakes of high-drag areas), ,detached' jets are formed in the downwind direction. (iii) Changes in surface elevation at a coast produce effects different from those of roughness; a positive wind jet forms parallel to the coast in the direction of the wind when the coast is on the right (looking downwind) and a negative jet when the coast is on the left. These jets do not increase in strength along the flow and do not persist downwind. (iv) Coriolis effects also determine how the inversion height varies near coastlines and surface roughness changes; for example, increasing/decreasing inland over a distance LR when stable airflow approaches from the sea and the coast is on the right/left of an observer looking downwind (opposite in the southern hemisphere). This mechanism is consistent with observed increasing/decreasing cloudiness inland from a coast. (v) Other effects occur where the surface elevation changes gradually over a distance of order LR (e.g. a wide, shallow valley); frictional effects are comparable with buoyancy and Coriolis forces, and flows perpendicular to the elevation change are deflected to the left (in the northern hemisphere), as observed in the Rhine valley. (vi) The shallow-layer model simulates the major features of the low-level flow field computed using the numerical mesoscale model with a horizontal resolution of 2 km, i.e. of order h0. Broad features were captured using a coarser resolution of 12 km. (vii) The analysis provides a method of estimating errors associated with finite grid size in numerical mesoscale models. Copyright © 2004 Royal Meteorological Society [source] |