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Acceleration

Distribution by Scientific Domains
Medical Sciences28%
Engineering20%
Life Sciences14%
Chemistry13%
Physics and Astronomy6%
Earth and Environmental Science5%
Polymers and Materials Science3%
Business, Economics, Finance and Accounting2%
5 Other Domains9%
Distribution within Medical Sciences
Cardiovascular Disease14%
Radiology & Imaging10%
36 Other Subdomains76%

Kinds of Acceleration

  • cardiac acceleration
  • centrifugal acceleration
  • dramatic acceleration
  • endocardial acceleration
    		•
  • flow acceleration
  • ground acceleration
  • growth acceleration
  • isovolumic acceleration
    		•
  • particle acceleration
  • peak endocardial acceleration
  • peak ground acceleration
  • rate acceleration
    		•
  • significant acceleration

    • Terms modified by Acceleration

  • acceleration effect
  • acceleration factor
    		•
  • acceleration length
  • acceleration response
    		•
  • acceleration term
  • acceleration time
    		•
  • acceleration time-of-flight

    • Selected Abstracts

    Social Acceleration: Ethical and Political Consequences of a Desynchronized High,Speed Society

    CONSTELLATIONS: AN INTERNATIONAL JOURNAL OF CRITICAL AND DEMOCRATIC THEORY, Issue 1 2003
    Hartmut Rosa
    First page of article [source]

    An experimental evaluation of ice cover effects on the dynamic behaviour of a concrete gravity dam

    EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 12 2002
    Patrick Paultre
    Abstract An extensive forced-vibration testing programme has been carried out on an 84-m concrete gravity dam located in northeastern Québec, Canada. The dam was subjected to a harmonic load on the crest in summer and severe winter conditions with temperatures ranging from ,10°C to ,15°C and a 1.0,1.5m ice cover. Acceleration and hydrodynamic frequency responses were obtained in different locations on the dam and in the reservoir. The main objective of the repeated tests was to investigate the effects of the ice cover on the dynamic behaviour of the dam,reservoir,foundation system, by comparing summer and winter results. Modifications in damping and resonance frequencies were observed, as well as an additional resonance that was attributed to an interaction of the dam with the ice cover. These findings provided a reliable and unique database for the investigations of dam,reservoir,foundation interaction and, in particular, the ice-cover effects for dams located in northern regions. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    An experimental investigation of water level effects on the dynamic behaviour of a large arch dam

    EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2001
    Jean Proulx
    Abstract The need for full-scale dynamic tests, which are recognized as the most reliable method to evaluate a structure's vibration properties, is increasing as new analysis techniques are developed that take into account the complex interaction phenomenons that occur in dam,reservoir,foundation systems. They are extremely useful to obtain reliable data for the calibration of newly developed numerical methods. The Earthquake Engineering and Structural Dynamics Research Center (CRGP) at the University of Sherbrooke has been developing and applying dynamic testing methods for large structures in the past 10 years. This paper presents the experimental evaluation of the effects of the varying water level on the dynamic response of the 180 m Emosson arch dam in Switzerland. Repeated forced-vibration tests were carried out on the dam during four different periods of the reservoir's filling cycle during a one-year span. Acceleration and hydrodynamic pressure frequency responses were obtained at several locations while the dam was subjected to horizontal harmonic loading. The variation of the resonant frequencies as a function of the reservoir level is investigated. A summary of the ongoing numerical correlation phase with a three-dimensional finite element model for the dam,reservoir,foundation system is also presented. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Catalysis by Ionic Liquids: Significant Rate Acceleration with the Use of [pmIm]Br in the Three-Component Synthesis of Dithio­carbamates

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 3 2008
    Brindaban C. Ranu
    Abstract An easily accessible neutral ionic liquid, 1-methyl-3-pentylimidazolium bromide, promoted a one-pot three-component condensation of an amine, carbon disulfide, and an activated alkene/dichloromethane/epoxide to produce the corresponding dithiocarbamates in high yields at room temperature. The reactions are very fast in ionic liquids relative to those in other reaction media. These reactions do not require any additional catalyst or solvent. The ionic liquid can be recovered and recycled for subsequent reactions. A plausible mechanism is suggested. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

    Acceleration of granulocyte colony-stimulating factor-induced neutrophilic nuclear lobulation by overexpression of Lyn tyrosine kinase

    FEBS JOURNAL, Issue 1 2002
    Tomomi Omura
    Stimulation with granulocyte colony-stimulating factor (G-CSF) induces myeloid precursor cells to differentiate into neutrophils, and tyrosine phosphorylation of certain cellular proteins is crucial to this process. However, the signaling pathways for neutrophil differentiation are still obscure. As the Src-like tyrosine kinase, Lyn, has been reported to play a role in G-CSF-induced proliferation in avian lymphoid cells, we examined its involvement in G-CSF-induced signal transduction in mammalian cells. Expression plasmids for wild-type Lyn (Lyn) and kinase-negative Lyn (LynKN) were introduced into a murine granulocyte precursor cell line, GM-I62M, that can respond to G-CSF with neutrophil differentiation, and cell lines that overexpressed these molecules (GM-Lyn, GM-LynKN) were established. Upon G-CSF stimulation, both the GM-Lyn and GM-LynKN cells began to differentiate into neutrophils, showing early morphological changes within a few days, much more rapidly than did the parental cells, which started to exhibit nuclear lobulation about 10 days after the cells were transferred to G-CSF-containing medium. However, the time course of expression of the myeloperoxidase gene, another neutrophil differentiation marker, was not affected by the overexpression of Lyn or LynKN. Therefore, in normal cells, protein interactions with Lyn, but not its kinase activity, are important for the induction of G-CSF-induced neutrophilic nuclear lobulation in mammalian granulopoiesis. [source]

    Cover Picture: Acceleration of Calcite Kinetics by Abalone Nacre Proteins (Adv. Mater.

    ADVANCED MATERIALS, Issue 22 2005
    22/2005)
    Abstract Abalone utilizes a system of macromolecular matrices and soluble proteins to produce beautiful and mechanically robust shells. The cover shows work by Qiu and co-workers reported on p.,2678, in which AP8 proteins isolated from the shell of red abalone are shown to alter the growth of calcite both by accelerating the rate and modifying the shape from the simple rhombohedra seen in the upper left of the scheme to the more complex form seem in the lower right. The changes are made manifest at an atomic scale through alterations in the growth speed and shape of the atomic steps that form the growth hillocks (background). [source]

    Acceleration of Calcite Kinetics by Abalone Nacre Proteins,

    ADVANCED MATERIALS, Issue 22 2005
    G. Fu
    Abalone shell nacre proteins act as surfactants to promote ion attachment at calcite steps, causing acceleration of the molecular-scale kinetics of calcite crystal growth. The proteins modify the shape of growing calcite (see Figure) through step-specific interactions, even though the proteins are larger than the atomic-scale steps. Understanding of crystal-growth control by interactions with proteins may give better control of new crystalline materials. [source]

    Acceleration of nitric oxide autoxidation and nitrosation by membranes

    IUBMB LIFE, Issue 4-5 2007
    Matias N. Möller
    Abstract The reaction between nitric oxide (,NO) and oxygen yields reactive species capable of oxidizing and nitrosating proteins, as well as deaminating DNA bases. Although this reaction is considered too slow to be biologically relevant, it has been shown that membranes, lipoproteins, mitochondria and possibly proteins can accelerate this reaction. This effect stems from the higher solubility of both ,NO and O2in the hydrophobic phase of these biological particles, leading to a concentration of both reagents and so a higher rate of reaction. It has been determined that this reaction occurs from 30 to 300 times more rapidly within the membrane, while even higher values have been suggested for proteins. The autoxidation of ,NO in membranes is not the main route for cellular ,NO consumption but an important consequence of this phenomenon is to focus the generation of significant amounts of oxidizing and nitrosating molecules (nitrogen dioxide and dinitrogen trioxide) in the small volume comprised by cellular membranes. Even so, these reactive species are diffusible and their ultimate fate will depend on the reactivity towards available substrates rather than on physical barriers. The acceleration of ,NO autoxidation by biological hydrophobic phases may thus be a general phenomenon that increases in importance in cases of ,NO overproduction. IUBMB Life, 59: 243-248, 2007 [source]

    Multiplicative random regression model for heterogeneous variance adjustment in genetic evaluation for milk yield in Simmental

    JOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 3 2008
    M.H. Lidauer
    Summary A multiplicative random regression (M-RRM) test-day (TD) model was used to analyse daily milk yields from all available parities of German and Austrian Simmental dairy cattle. The method to account for heterogeneous variance (HV) was based on the multiplicative mixed model approach of Meuwissen. The variance model for the heterogeneity parameters included a fixed region × year × month × parity effect and a random herd × test-month effect with a within-herd first-order autocorrelation between test-months. Acceleration of variance model solutions after each multiplicative model cycle enabled fast convergence of adjustment factors and reduced total computing time significantly. Maximum Likelihood estimation of within-strata residual variances was enhanced by inclusion of approximated information on loss in degrees of freedom due to estimation of location parameters. This improved heterogeneity estimates for very small herds. The multiplicative model was compared with a model that assumed homogeneous variance. Re-estimated genetic variances, based on Mendelian sampling deviations, were homogeneous for the M-RRM TD model but heterogeneous for the homogeneous random regression TD model. Accounting for HV had large effect on cow ranking but moderate effect on bull ranking. [source]

    Validation of a New Noninvasive Device for the Monitoring of Peak Endocardial Acceleration in Pigs: Implications for Optimization of Pacing Site and Configuration

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2008
    PIERRE BORDACHAR M.D.
    Introduction: The peak of endocardial acceleration (PEA) is an index of myocardial contractility. We aimed to (1) demonstrate that the PEA measured by the noninvasive cutaneous precordial application of an accelerometer sensor is related to left ventricular (LV) dP/dt max and (2) assess the usefulness of PEA monitoring during graded ischemia and during different configurations of sequential biventricular pacing. Methods and Results: Measurements of invasive LV dP/dt max were compared with measurements of transcutaneous PEA in seven pigs at baseline and during acute drug infusions; increased heart rate; right, left, biventricular and sequential biventricular pacing before and after graded ischemia induced by the constriction of the left anterior descending coronary artery. A consistent PEA signal was obtained in all animals. PEA changes were highly related to LV dP/dt max changes (r= 0.93; P < 0.001). The changes of LV contractility induced by the different pacing configurations were detected by PEA analysis in the absence of ischemia (r= 0.94; P < 0.001) and in the presence of ischemic LV dysfunction (r= 0.91; P < 0.001). Conclusion: Noninvasive PEA measurement allows monitoring of left ventricular contractility and may be a useful tool to detect global effect of ventricular ischemia and to optimize the choice of both pacing site and pacing configuration. [source]

    Analysis of Implantable Cardioverter Defibrillator Therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2003
    RICHARD C. KLEIN M.D.
    Introduction: The implantable cardioverter defibrillator (ICD) is commonly used to treat patients with documented sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). Arrhythmia recurrence rates in these patients are high, but which patients will receive a therapy and the forms of arrhythmia recurrence (VT or VF) are poorly understood. Methods and Results: The therapy delivered by the ICD was examined in 449 patients randomized to ICD therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial. Events triggering ICD shocks or antitachycardia pacing (ATP) were reviewed for arrhythmia diagnosis, clinical symptoms, activity at the onset of the arrhythmia, and appropriateness and results of therapy. Both shock and ATP therapies were frequent by 2 years, with 68% of patients receiving some therapy or having an arrhythmic death. An appropriate shock was delivered in 53% of patients, and ATP was delivered in 68% of patients who had ATP activated. The first arrhythmia treated in follow-up was diagnosed as VT (63%), VF (13%), supraventricular tachycardia (18%), unknown arrhythmia (3%), or due to ICD malfunction or inappropriate sensing (3%). Acceleration of an arrhythmia by the ICD occurred in 8% of patients who received any therapy. No physical activity consistently preceded arrhythmias, nor did any single clinical factor predict the symptoms of the arrhythmia. Conclusion: Delivery of ICD therapy in AVID patients was common, primarily due to VT. Inappropriate ICD therapy occurred frequently. Use of ICD therapy as a surrogate endpoint for death in clinical trials should be avoided. (J Cardiovasc Electrophysiol, Vol. 14, pp. 940-948, September 2003) [source]

    Late Acceleration of Treated Uncontrolled Hypertension

    JOURNAL OF CLINICAL HYPERTENSION, Issue 10 2008
    Joel Handler MD
    First page of article [source]

    Enhanced docking with the mining minima optimizer: Acceleration and side-chain flexibility

    JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 16 2002
    Visvaldas Kairys
    Abstract The ligand,protein docking algorithm based on the Mining Minima method has been substantially enhanced. First, the basic algorithm is accelerated by: (1) adaptively determining the extent of each energy well to help avoid previously discovered energy minima; (2) biasing the search away from ligand positions at the surface of the receptor to prevent the ligand from staying at the surface when large sampling regions are used; (3) quickly testing multiple different ligand positions and orientations for each ligand conformation; and (4) tuning the source code to increase computational efficiency. These changes markedly shorten the time needed to discover an accurate result, especially when large sampling regions are used. The algorithm now also allows user-selected receptor sidechains to be treated as mobile during the docking procedure. The energies associated with the mobile side chains are computed as if they belonged to the ligand, except that atoms at the boundary between side chains and the rigid backbone are treated specially. This new capability is tested for several well-known ligand/protein systems, and preliminary application to an enzyme whose substrate is unknown,the recently solved hypothetical protein YecO (HI0319) from Haemophilus influenzae,indicates that side-chains relaxations allow candidate substrates of various sizes to be accommodated. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 1656,1670, 2002 [source]

    Acceleration of Cheddar Cheese Lipolysis by Using Liposome-entrapped Lipases

    JOURNAL OF FOOD SCIENCE, Issue 2 2002
    E.E. Kheadr
    ABSTRACT: Two types of lipase (Palatase M and Lipase 50) were encapsulated in liposomes with trapping efficiencies of 35.9 and 40.3%, respectively. The lipases were incorporated into cheese milk at levels of 0.2, 0.5, and 1.0 lipase units/g fat. Treated cheeses had higher moisture and lower protein, fat, and ash contents than the control cheese and they were less firm, but more elastic and cohesive, than the control cheese. Production of free fatty acids was accelerated by the addition of encapsulated enzymes. Cheeses with up to 0.5 lipase unit/g milk fat had slightly better flavor intensities than control cheese. Cheeses with the highest level of Palatase M and Lipase 50 developed a pronounced soapy off-flavor after 2 and 3 mo of ripening, respectively. [source]

    Skeletal Growth Acceleration with Growth Hormone Secretagogues in Transgenic Growth Retarded Rats: Pattern-Dependent Effects and Mechanisms of Desensitization

    JOURNAL OF NEUROENDOCRINOLOGY, Issue 6 2001
    T. Wells
    Abstract The transgenic growth retarded (Tgr) rat is the first genetic model of growth hormone (GH) deficiency whose growth can be accelerated with exogenous GH secretagogues (GHSs). In this study, we have demonstrated that GHS-receptor (GHS-R) mRNA expression in the arcuate nucleus of Tgr rats was not significantly different to that in wild-type littermates. We have confirmed that GHS-induced elevation in body weight gain was accompanied by acceleration of skeletal growth, and that the effects of the GHS, GHRP-6, were both dose- and pattern-dependent. The growth response with continuous infusion of GHRP-6 was transient, accompanied by suppression of GH and corticosterone responses to bolus injection of GHRP-6. This desensitization occurred without downregulation of arcuate GHS-R mRNA expression, but was accompanied by elevated periventricular somatostatin mRNA expression. In contrast, pulsatile (3-hourly) infusion of GHRP-6 produced sustained growth and GH responses, which were accompanied by suppression of corticosterone responses and elevated arcuate GH-releasing factor (GRF) mRNA expression. Skeletal growth was further accelerated by coinfusion of GRF, but significant depletion of pituitary GH stores suggested that this growth rate may not be sustainable. These experiments confirm the importance of the Tgr rat for investigating the growth promoting potential of the GHSs in the context of GH-deficient dwarfism, and suggest that elevated somatostatin expression may mediate the suppression of the GRF-GH and hypothalamo-pituitary-adrenal axes following continuous GHRP-6 treatment. [source]

    Acceleration of cartilage repair by genetically modified chondrocytes over expressing bone morphogenetic protein-7

    JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2003
    Chisa Hidaka
    Background: Cartilage has a limited capacity to heal. Although chondrocyte transplantation is a useful therapeutic strategy, the repair process can be lengthy. Previously we have shown that over expression of bone morphogenetic protein-7 (BMP-7) in chondrocytes by adenovirus-mediated gene transfer leads to increased matrix synthesis and cartilage-like tissue formation in vitro. In this context we hypothesized that implantation of genetically modified chondrocytes expressing BMP-7 would accelerate the formation of hyaline-like repair tissue in an equine model of cartilage defect repair. Methods: Chondrocytes treated with adenovirus vector encoding BMP-7 (AdBMP-7) or as control, an adenovirus vector encoding an irrelevant gene (Escherichia coli cytosine deaminase, AdCD) were implanted into extensive (15 mm diameter) articular cartilage defects in the patellofemoral joints of 10 horses. Biopsies were performed to evaluate early healing at 4 weeks. At the terminal time point of 8 months, repairs were assessed for morphology, MRI appearance, compressive strength, biochemical composition and persistence of implanted cells. Results: Four weeks after surgery AdBMP-7-treated repairs showed an increased level of BMP-7 expression and accelerated healing, with markedly more hyaline-like morphology than control. Quantitative real-time polymerase chain reaction (PCR) analysis of the repair tissue 8 months after surgery showed that few implanted cells persisted. By this time, the controls had healed similarly to the AdBMP-7-treated defects, and no difference was detected in the morphologic, biochemical or biomechanical properties of the repair tissues from the two treatment groups. Conclusions: Implantation of genetically modified chondrocytes expressing BMP-7 accelerates the appearance of hyaline-like repair tissue in experimental cartilage defects. Clinical relevance: Rehabilitation after cell-based cartilage repair can be prolonged, leading to decreased patient productivity and quality of life. This study shows the feasibility of using genetically modified chondrocytes to accelerate cartilage healing. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source]

    Is the Strength of Implicit Alcohol Associations Correlated with Alcohol-induced Heart-rate Acceleration?

    ALCOHOLISM, Issue 8 2006
    Esther Van Den Wildenberg
    Background: Heart rate (HR) acceleration during the ascending limb of the blood alcohol curve has proven to be a reliable measure of the sensitivity to the activating effects of alcohol. In this study, we investigated the correlation between an ethanol-induced cardiac change and the strength of implicit alcohol-related arousal and approach associations and attentional bias for alcohol-related stimuli in heavy drinkers. These 3 types of implicit alcohol-related cognitions have been proposed to reflect the strength of incentive sensitization that is experienced after repeated alcohol use. Methods: Forty-eight heavy drinking men performed a modified version of the Implicit Association Test (IAT) to measure their implicit alcohol arousal and approach,avoidance associations. A modified version of the emotional Stroop was used to measure attentional bias for alcohol-related stimuli (blocked and unblocked). Next, a high dose of alcohol (1.0 mL/kg body weight 95% USP alcohol) was administered in a short period of time. Resting baseline HR, blood alcohol concentrations, mood, and craving for alcohol were assessed before alcohol administration and for 2 hours post,alcohol consumption. Results: Contrary to our hypothesis, a negative association was found between implicit arousal associations and alcohol-induced HR change. This indicates that strong arousal associations were correlated with a decrease in alcohol-induced HR. Approach associations and attentional bias were not correlated with alcohol-induced HR change, but both were correlated positively with each other. Conclusions: Alcohol-arousal associations and other implicit cognitions (attentional bias, approach associations) are not positively related to individual differences in the sensitivity to alcohol's activating effects, at least not in the present sample consisting primarily of family history-negative heavy drinkers. [source]

    Acceleration of absolute negative mobility

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 10 2007
    Jan Regtmeier
    Abstract Recently, the counter intuitive migration phenomenon of absolute negative mobility (ANM) has been demonstrated to occur for colloidal particles in a suitably arranged post array within a microfluidic device [1]. This effect is based on the interplay of Brownian motion, nonlinear dynamics induced through microstructuring, and nonequilibrium driving, and results in a particle movement opposite to an applied static force. Simultaneously, the migration of a different particle species along the direction of the static force is possible [19], thus providing a new tool for particle sorting in microfluidic device format. The so far demonstrated maximum velocities for micrometer-sized spheres are slow, i. e., in the order of 10 nm per second. Here, we investigate numerically, how maximum ANM velocities can be significantly accelerated by a careful adjustment of the post size and shape. Based on this numerical analysis, a post design is developed and tested in a microfluidic device made of PDMS. The experiment reveals an order of magnitude increase in velocity. [source]

    Acceleration of ALA-induced PpIX fluorescence development in the oral mucosa

    LASERS IN SURGERY AND MEDICINE, Issue 3 2003
    Sirintra Charoenbanpachon
    Abstract Background and Objectives The development of 5-aminolevulinic acid (ALA)-induced tissue fluorescence is optimal 2,4 hours after ALA application. Goal of this work was to develop a means of accelerating oral topical ALA-induced tissue fluorescence. Study Design/Materials and Methods In 300 hamsters, DMBA (9,10 dimethyl-1,2-benzanthracene) cheek pouch carcinogenesis produced dysplasia in 3,5 weeks. Topical application of 20% ALA in Eucerin was followed by localized ultrasound treatment (1, 3.3 MHz) in 150 animals. In 75 animals, ALA was applied in an Oral Pluronic Lecithin Organogel (OPLO,an absorption enhancer) vehicle. Seventy-five animals received only topical ALA in Eucerin. Hamsters were sacrificed and cryosections underwent fluorescence measurements, histological evaluation, 20,180 minutes after ALA application. One-way ANOVA detected independent effects of pathology on laser-induced fluorescence (LIF). Two-way ANOVA tested for independent effect of pathology and of OPLO, ultrasound, and interaction effects. Results Ultrasound significantly (P,<,0.05) accelerated tissue fluorescence development. Conclusions Low-frequency ultrasound can accelerate ALA-induced fluorescence development. Lasers Surg. Med. 32:185,188, 2003. © 2003 Wiley-Liss, Inc. [source]

    Relationship between Amplitude and Timing of Heart Sounds and Endocardial Acceleration

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2009
    AUDE TASSIN M.D.
    Objective: To study the correlation between heart sounds and peak endocardial acceleration (PEA) amplitudes and timings, by modulation of paced atrioventricular (AV) delay in recipients of dual chamber pacemakers. Methods: Ten recipients of dual chamber pacemakers implanted for high-degree AV block were studied. Endocardial acceleration (EA) and phonocardiographic and electrocardiographic signals were recorded during performance of an AV delay scan in VDD and DDD modes. Results: First PEA (PEA I) and first heart sound (S1) changed similarly with the AV delay. A close intrapatient correlation was observed between S1 and PEA I amplitudes in all patients (P < 0.0001). The interpatient normalized PEA I to S1 amplitudes correlation was r = 0.89 (P < 0.0001) in DDD mode, and r = 0.81 (P < 0.0001) in VDD mode. The mean cycle-by-cycle PEA I to S1 delay was ,4.3 ± 22 ms and second PEA (PEA II) to second heart sound (S2) delay was ,7.7 ± 15 ms. Conclusions: A close correlation was observed between PEA I and S1 amplitudes and timings, and between PEA II and S2 timings. These observations support the hypothesis that PEA and heart sounds are manifestations of the same phenomena. EA might be a useful tool to monitor cardiac function. [source]

    Programming Optimal Atrioventricular Delay in Dual Chamber Pacing Using Peak Endocardial Acceleration: Comparison with a Standard Echocardiographic Procedure

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1p2 2003
    JEAN-MARC DUPUIS
    DUPUIS, J.-M.,et al.: Programming Optimal Atrioventricular Delay in Dual Chamber Pacing Using Peak Endocardial Acceleration: Comparison with a Standard Echocardiographic Procedure.Optimization of programmed atrioventricular delay in dual chamber pacing is essential to the hemodynamic efficiency of the heart. Automatic AV delay optimization in an implanted pacemaker is highly desirable. Variations of peak endocardial acceleration (PEA) with AV delay at rest correlate well with echocardiography derived observations, particularly with end-diastolic filling and mitral valve closure timings. This suggests the possibility of devising a procedure for the automatic determination of the optimal AV delay. The aim of this study was to compare a proposed algorithm for optimal AV delay determination with an accepted echocardiographic method. Fifteen patients with high degree AV block received BEST-Living pacing systems. Automatic AV delay scans were performed at rest (60,300 ms in 20-ms steps with 60 beats per step) in DDD at 90 ppm, while simultaneously recording cycle-by-cycle PEA values, which were averaged for each AV delay to obtain a PEA versus AV delay curve. Nonlinear regression analysis based on a Boltzmann sigmoid curve was performed, and the optimal AV delay (OAVD) was chosen as the sigmoid inflection point of the regression curve. The OAVD was also evaluated for each patient using the Ritter echocardiographic method. Good sigmoid fit was obtained in 13 of 15 patients. The mean OAVD obtained by the PEA sigmoid algorithm was146.9 ± 32.1 ms, and the corresponding result obtained by echocardiography was156.4 ± 34.3 ms(range 31.8,39.7 ms). Correlation analysis yielded r = 0.79, P = 0.0012. In conclusion, OAVD estimates obtained by PEA analysis during automatic AV delay scanning are consistent with those obtained by echocardiography. The proposed algorithm can be used for automatic OAVD determination in an implanted pacemaker pulse generator. (PACE 2003; 26:[Pt. II]:210,213) [source]

    Acceleration of lung disease in children with cystic fibrosis after Pseudomonas aeruginosa acquisition

    PEDIATRIC PULMONOLOGY, Issue 4 2001
    Michael R. Kosorok PhD
    Abstract As part of the ongoing Wisconsin Cystic Fibrosis (CF) Neonatal Screening Project, we had the unique opportunity to study the longitudinal relationship between Pseudomonas aeruginosa (Pa) acquisition and infection and developing lung disease in children with CF. The primary objective was to determine whether acquisition of Pa was associated with a measurable change in the progression of lung disease. Two outcome measures were used to study 56 patients who were diagnosed through newborn screening: 1) Wisconsin additive chest radiograph score (WCXR), based on the average of scores from a pulmonologist and a radiologist, and 2) the highest forced expired volume in 1 sec (FEV1)/forced vital capacity (FVC) ratio. We used two measures of Pa acquisition: 1) time of first positive protocol-determined oropharyngeal (with cough) culture, and 2) the magnitude of antibody titer detected by ELISA assays, using as antigen a crude cell lysate, purified exotoxin A, or an elastase toxoid prepared from three Pa strains. Other predictor variables included age, pancreatic status, height-for age, and weight-for-age-percentiles. The best regression model for predicting changes in the WCXR included time to first positive culture and antibody titer for Pa elastase. Prior to Pa acquisition, WCXR worsened by 0.45 points/year (P,>,0.25); after Pa acquisition, the rate of worsening increased significantly (P,<,0.001) to 1.40 points/year. Each antibody titer level (log base 2) increased the score by 0.48 points (P,<,0.001). The best regression model for predicting change in the FEV1/FVC included only time to first positive culture. Prior to Pa acquisition, the FEV1/FVC ratio declined by 1.29%/year; after Pa infection, the rate of decrease significantly accelerated to 1.81%/year (P,=,0.001). Our data show that Pa acquisition is associated with declining pulmonary status in children with CF, and that this effect is probably gradual rather than precipitous. Because these patients were diagnosed and treated aggressively, our estimates of the effects of Pa acquisition may be conservative. We also conclude that the WCXR appears to be more sensitive than FEV1/FVC in detecting early changes in lung disease associated with CF. Pediatr Pulmonol. 2001; 32:277,287. © 2001 Wiley-Liss, Inc. [source]

    Photoperiodic and temperature control of nymphal development and induction of reproductive diapause in two predatory Orius bugs: interspecific and geographic differences

    PHYSIOLOGICAL ENTOMOLOGY, Issue 4 2008
    DMITRY L. MUSOLIN
    Abstract The effects of day-length and temperature on pre-adult growth and induction of reproductive diapause are studied in Orius sauteri and Orius minutus (Heteroptera: Anthocoridae) from northern (43.0°N, 141.4°E) and central (36.1°N, 140.1°E) Japan. In the north, at 20 °C, pre-adult growth is slower under an LD 14 : 10 h photoperiod than under shorter or longer photophases. At 24 and 28 °C, the longer photophases result in shorter pre-adult periods. Acceleration of nymphal growth by short days in autumn appears to be adaptive. In the central region, this response is less pronounced, suggesting that timing of adult emergence is less critical than in the north. Day length also influences the thermal requirements for pre-adult development. The slope of the regression line representing temperature dependence of pre-adult development is significantly smaller and the lower development threshold (LDT) is significantly lower under an LD 12 : 12 h photoperiod than under long-day conditions. The weaker dependence of nymphal growth on temperature and the lower LDT in autumn might be adaptive. In the north, increased temperature shifts the critical day length of diapause induction and suppresses the photoperiodic response in O. sauteri but not in O. minutus. Further south, the incidence of diapause in both species is low even under short-day conditions but the same interspecific difference is observed (i.e. increase of temperature affects the response in O. sauteri but not in O. minutus). This suggests seasonally earlier diapause induction with weaker temperature dependence in O. minutus than in O. sauteri. [source]

    Cofactor effects on the protein folding reaction: Acceleration of ,-lactalbumin refolding by metal ions

    PROTEIN SCIENCE, Issue 4 2006
    Natalia A. Bushmarina
    Abstract About 30% of proteins require cofactors for their proper folding. The effects of cofactors on the folding reaction have been investigated with ,-lactalbumin as a model protein and metal ions as cofactors. Metal ions accelerate the refolding of ,-lactalbumin by lessening the energy barrier between the molten globule state and the transition state, mainly by decreasing the difference of entropy between the two states. These effects are linked to metal ion binding to the protein in the native state. Hence, relationships between the metal affinities for the intermediate states and those for the native state are observed. Some residual specificity for the calcium ion is still observed in the molten globule state, this specificity getting closer in the transition state to that of the native state. The comparison between kinetic and steady-state data in association with the , value method indicates the binding of the metal ions on the unfolded state of ,-lactalbumin. Altogether, these results provide insight into cofactor effects on protein folding. They also suggest new possibilities to investigate the presence of residual native structures in the unfolded state of protein and the effects of such structures on the protein folding reaction and on protein stability. [source]

    Acceleration of the onset of collagen-induced arthritis by a deficiency of platelet endothelial cell adhesion molecule 1

    ARTHRITIS & RHEUMATISM, Issue 11 2003
    Yoshifumi Tada
    Objective Platelet endothelial cell adhesion molecule 1 (PECAM-1; CD31) is a member of the immunoglobulin superfamily that is expressed in platelets, leukocytes, and endothelial cells. PECAM-1 has been shown to play a role in transendothelial migration of leukocytes and contains immunoreceptor tyrosine-based inhibitory motifs in its cytoplasmic tail and inhibits cellular responses. We examined the role of PECAM-1 in the development of collagen-induced arthritis (CIA). Methods CIA was induced in PECAM-1,deficient DBA/1 mice. The incidence of arthritis and the arthritis index were examined. Anti,type II collagen (anti-CII) antibody levels and interferon-, (IFN,) production by lymph node cells and spleen cells were determined. Lymphocytes from arthritic PECAM-1,deficient and wild-type mice were labeled with dye, transferred to arthritic PECAM-1+/, mice, and cell migration to inflamed joints was examined. Results PECAM-1,deficient mice showed accelerated onset of arthritis and increased severity only during the early phase. Anti-CII antibody levels were also increased during the early phase. IFN, production by lymph node cells and spleen cells from PECAM-1,deficient mice in response to CII was higher than that in wild-type mice. Lymphocytes from arthritic PECAM-1,deficient mice showed accelerated migration to inflamed joints, but not lymph nodes or spleen. The development of anti-CII antibody,induced arthritis was similar in PECAM-1,deficient and wild-type mice. Conclusion These results indicate that PECAM-1 negatively regulates humoral and cell-mediated immune responses and lymphocyte migration into joints and, consequently, the development of CIA. In addition, the role of PECAM-1 in the transendothelial migration of leukocytes appears to be redundant in this model. [source]

    Acceleration of germination and early growth of wheat and bean seedlings grown under various magnetic field and osmotic conditions

    BIOELECTROMAGNETICS, Issue 2 2010
    Turgay Cakmak
    Abstract Magnetic field (MF) can have different effects on plant metabolism depending on its application style, intensity, and environmental conditions. This study reports the effects of different intensities of static MF (4 or 7,mT) on seed germination and seedling growth of bean or wheat seeds in different media having 0, 2, 6, and 10 atmosphere (atm) osmotic pressure prepared with sucrose or salt. The germination percentages of the treated seeds were compared with untreated seeds germinated in different osmotic pressure during 7 days of incubation. The application of both MFs promoted the germination ratios of bean and wheat seeds, regardless of increasing osmotic pressure of sucrose or salt. Growth data measured on the 7th day showed that the treated plants grew faster than control. After 7 days of incubation, the mean length of treated seedlings was statistically higher than control plants in all the media. The greatest germination and growth rates in both plants were from the test groups exposed to 7,mT MF. Strikingly, effects of static MF on germination and growth increased positively with increasing osmotic pressure or salt stress compared to their respective controls. On the other hand, MF application caused an increase in dry biomass accumulation of root and shoots of both seedlings; however, this effect was found statistically important in all the conditions for wheat but not for bean, in general. Bioelectromagnetics 31:120,129, 2010. © 2009 Wiley-Liss, Inc. [source]

    Acceleration of Short Helical Peptide Conformational Dynamics by Trifluoroethanol in an Organic Solvent

    CHEMBIOCHEM, Issue 7 2005
    Matthew Kubasik Prof.
    Solvent dependency. The influence of the cosolvent trifluorethanol on the rate of enantiomerization of an octameric peptide (see figure) in CD2Cl2 solution is described. Kinetic data have been taken over a range of temperatures, thus allowing for a discussion of the enthalpic and entropic origins of the catalytic effect. [source]

    ChemInform Abstract: Remarkable Acceleration of Cyanosilylation by the Mesoporous Al-MCM-41 Catalyst.

    CHEMINFORM, Issue 28 2008
    Katsuyuki Iwanami
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    Increased Enantioselectivity and Remarkable Acceleration of Lipase-Catalyzed Transesterification by Using an Imidazolium PEG,Alkyl Sulfate Ionic Liquid.

    CHEMINFORM, Issue 14 2007
    Toshiyuki Itoh
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

    Steric Acceleration of Activated Ene Reactions.

    CHEMINFORM, Issue 24 2005
    Peter G. Sammes
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]