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Tilt

Distribution by Scientific Domains
Medical Sciences33%
Physics and Astronomy18%
Chemistry14%
Life Sciences9%
Earth and Environmental Science6%
Business, Economics, Finance and Accounting5%
Engineering4%
Polymers and Materials Science3%
3 Other Domains8%
Distribution within Medical Sciences
Anesthesia & Pain Management24%
Cardiovascular Disease21%
Neurology9%
11 Other Subdomains46%

Kinds of Tilt

  • head-down tilt
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  • head-up tilt
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  • pelvic tilt
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    Terms modified by Tilt

  • tilt angle
  • tilt boundary
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  • tilt grain boundary
  • tilt system
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  • tilt test
  • tilt testing
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    Selected Abstracts

    Tilt or Pulse Duration,Which is the Decisive Parameter in Defibrillation?

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 10 2007
    WERNER IRNICH Ph.D.
    No abstract is available for this article. [source]

    Tilt of InGaN layers on miscut GaN substrates

    PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 7 2010
    M. Kry
    Abstract We report on the crystallographic orientation of InGaN layers grown on GaN substrates with a miscut with respect to c -planes up to 2.5°. The samples were examined using high-resolution X-ray diffraction (HRXRD) and atomic force microscopy (AFM). Because of the large (up to about 2% in this study) lattice mismatch between InGaN and GaN, an additional tilt between the c lattice planes of InGaN and GaN was observed and explained by using the Nagai model [J. Appl. Phys. 45, 3789 (1974)]. We observed that for part of the samples, this tilt is about 10% smaller compared to the one predicted by the model. The experimental data are important for understanding the microstructure of InGaN layers grown on substrates of non-perfect morphology. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Ausstattung von Klassenräumen mit Einrichtungen zum Temperieren, Lüften und Belichten

    BAUPHYSIK, Issue 3 2009
    Gruppenleiterin Raumklimaqualität Runa Tabea Hellwig Dr.-Ing.
    Bauphysik allgemein; Energieeinsparung Abstract Fast alle Schulräume werden in Deutschland ausschließlich über Fenster mit Außenluft versorgt. Messungen haben gezeigt, dass die Belüftung der Schulräume vor allem in der kalten Jahreszeit unzureichend ist. Hybride Lüftungssysteme mit einer automatischen Unterstützung der Fensterlüftung könnten eine Möglichkeit bieten, die Häufigkeit schlechter Innenluftqualität in Schulen zu minimieren. Hierbei ist die Anordnung der dezentralen Zuluftöffnungen in den Fassaden eine der kritischsten Systemkomponenten, und es besteht gerade bei Schulgebäuden weiterer Untersuchungs- und Optimierungsbedarf. Im Rahmen des vom Bundesministerium für Wirtschaft und Technologie geförderten Verbund- projektes "Heizenergieeinsparung, thermische Behaglichkeit und gute Luftqualität in Schulgebäuden durch hybride Lüftungstechnik" werden die Eigenschaften von Klassenräumen im Landkreis Miesbach bezüglich der Temperierung, Belüftung und Belichtung aufgenommen. Die Begehung von 22 Schulen im Landkreis Miesbach ermöglicht für einen gesamten Landkreis die Bewertung der baulichen Gegebenheiten, welche die raumklimatischen Verhältnisse entscheidend beeinflussen. Die Belegungsdichte der Klassenräume im Landkreis Miesbach ist eher als normal bis gering einzustufen, da in ca. 80 % der Räume der Mindestwert von 2 m2 je Schüler eingehalten wird. 88 % der untersuchten Räume weisen eine mittlere bis hohe thermische Masse auf. Die meisten Klassenräume im Landkreis haben einen Fensterflächenanteil von 30 bis 60 %. Etwa 50 % der Räume besitzen keinen Sonnenschutz. Der bauliche sommerliche Wärmeschutz muss überwiegend als unzureichend bewertet werden. Etwa zwei Drittel der Klassenräume weisen eine gute bis mittlere Tageslichtversorgung auf. Die Klassenräume werden über Fenster belüftet. Die Fassaden besitzen vielfältige Öffnungsmöglichkeiten, wobei Drehkippflügel und Schwingflügel am häufigsten angetroffen werden. Equipment of classrooms with systems for maintaining temperature, for ventilation and for illumination. Most German classrooms are not equipped with mechanical ventilation systems. Natural ventilation controlled by the occupants opening the windows is the main way to provide fresh air. Measurements in real classrooms showed that the ventilation especially in cold season is insufficient. Hydrid ventilation systems with automatically controlled windows might reduce the prevalence of high carbon dioxide concentration inside the classrooms. The position of the air supply opening in the façade is the most sensible design task. There is still a big potential for optimization. In the frame of the project "Energy saving, thermal comfort and good indoor air quality in schools using hybrid ventilation" supported by the German Federal Ministry for Economic Affairs and Technology the properties of classrooms in the county Miesbach/Germany regarding thermal comfort, ventilation and illumination were collected. In sum data of 106 classrooms in 22 schools were collected. The density of persons is normal to low. Approximately 80% of the rooms offer at least 2 or more square meter per pupil. 88% of the investigated classrooms are built with medium or high thermal mass. The glazed facade area is between 30 and 60% for most of the classrooms. 50% of the classrooms do not have any sun shading device. The summer overheating protection by passive means is insufficient. Two thirds of the classrooms offer a good to acceptable daylight condition. The classrooms are ventilated by opening the windows. There are different opening types of the windows and several combinations of the types in the façades. Tilt and turn windows and the horizontally pivot-hung type are the most prevalent types. [source]

    Symmetry rules and strain/order-parameter relationships for coupling between octahedral tilting and cooperative Jahn,Teller transitions in ABX3 perovskites.

    ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2009

    The structural evolution of selected perovskites containing Jahn,Teller cations has been investigated in the light of a formal analysis of symmetry hierarchies for phase transitions driven by octahedral tilting and Jahn,Teller cooperative distortions. General expressions derived from the strain/order-parameter coupling relationships allowed by symmetry are combined with observed changes in lattice parameters to reveal details of order-parameter evolution and coupling. LuVO3, YbVO3, YVO3 and CeVO3 are representative of systems which develop Jahn,Teller ordering schemes associated with irreducible representations and of the space group . Tilting of their octahedra is associated with and . The Pnma ( tilting) ,P21/a ( tilting, Jahn,Teller order) transition below room temperature is close to second order in character. Shear strains which depend primarily on tilt angles show little variation, implying that there is only weak coupling between the tilting and Jahn,Teller order parameters. The subsequent P21/a,Pnma ( tilting, Jahn,Teller order) is first order in character, and involves either a reduction in the tilt angle or a change in the strength of tilt/Jahn,Teller order-parameter coupling. In LaMnO3, the isosymmetric Pnma ( tilting) ,Pnma ( tilting, Jahn,Teller order) transition can be described in terms of a classical first-order transition conforming to a 246 Landau expansion with negative fourth-order coefficients. Strain evolution in Ba-doped samples suggests that the transition becomes second order in character and reveals a new strain relaxation mechanism in LaMnO3 which might be understood in terms of local strain heterogeneities due to the disordering of distorted MnO6 octahedra. Transitions in PrAlO3 and La0.5Ba0.5CoO3 illustrate the transformation behaviour of systems in which the Jahn,Teller ordering scheme is associated with the irreducible representation . Overall, coupled tilting + Jahn,Teller phase transitions in perovskites conform to mean-field behaviour, consistent with the underlying role of strain in promoting long interaction lengths. [source]

    The role of the ,-adrenergic receptor in the leg vasoconstrictor response to orthostatic stress

    ACTA PHYSIOLOGICA, Issue 3 2009
    M. Kooijman
    Abstract Aim:, The prompt increase in peripheral vascular resistance, mediated by sympathetic ,-adrenergic stimulation, is believed to be the key event in blood pressure control during postural stress. However, despite the absence of central sympathetic control of the leg vasculature, postural leg vasoconstriction is preserved in spinal cord-injured individuals (SCI). This study aimed at assessing the contribution of both central and local sympathetically induced ,-adrenergic leg vasoconstriction to head-up tilt (HUT) by including healthy individuals and SCI, who lack central sympathetic baroreflex control over the leg vascular bed. Methods:, In 10 controls and nine SCI the femoral artery was cannulated for drug infusion. Upper leg blood flow (LBF) was measured bilaterally using venous occlusion strain gauge plethysmography before and during 30° HUT throughout intra-arterial infusion of saline or the non-selective ,-adrenergic receptor antagonist phentolamine respectively. Additionally, in six controls the leg vascular response to the cold pressor test was assessed during continued infusion of phentolamine, in order to confirm complete ,-adrenergic blockade by phentolamine. Results:, During infusion of phentolamine HUT still caused vasoconstriction in both groups: leg vascular resistance (mean arterial pressure/LBF) increased by 10 ± 2 AU (compared with 12 ± 2 AU during saline infusion), and 13 ± 3 AU (compared with 7 ± 3 AU during saline infusion) in controls and SCI respectively. Conclusion:, Effective ,-adrenergic blockade did not reduce HUT-induced vasoconstriction, regardless of intact baroreflex control of the leg vasculature. Apparently, redundant mechanisms compensate for the absence of sympathetic ,-adrenoceptor leg vasoconstriction in response to postural stress. [source]

    Spatially resolved X-ray diffraction as a tool for strain analysis in laterally modulated epitaxial structures

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2009
    A. Wierzbicka
    Abstract Spatially resolved X-ray diffraction (SRXRD) is applied for micro-imaging of strain in laterally modulated epitaxial structures. In GaAs layers grown by liquid phase epitaxial lateral overgrowth (ELO) on SiO2 -masked GaAs substrates a downward tilt of ELO wings caused by their interaction with the mask is observed. The distribution of the tilt magnitude across the wings width is determined with ,m-scale spatial resolution. This allows measuring of the shape of the lattice planes in individual ELO stripes. If a large area of the sample is studied the X-ray imaging provides precise information on the tilt of an individual wing and its distribution. In heteroepitaxial GaSb/GaAs ELO layers local mosaicity in the wing area is found. By the SRXRD the size of microblocks and their relative misorientation were analyzed. Finally, the SRXRD technique was applied to study distribution of localized strain in AlGaN epilayers grown by MOVPE on bulk GaN substrates with AlN mask. X-ray mapping proves that by mask patterning strain in AlGaN layer can be easily engineered, which opens a way to produce thicker, crack-free AlGaN layers with a higher Al content needed in GaN-based laser diodes. All these examples show that high spatial and angular resolutions offered by SRXRD makes the technique a powerful tool to study local lattice distortions in semiconductor microstructures. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Effects of alcohol and smoking during pregnancy on infant autonomic control

    DEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2009
    William P. Fifer
    Abstract Prenatal exposure to smoking and alcohol increases the risk for Sudden Infant Death Syndrome (SIDS). Physiological changes associated with these exposures are not well studied. Full-term infants were tested within the first 3 days of life. We hypothesized that maternal alcohol consumption and/or smoking during pregnancy would alter autonomic nervous system function. Newborns whose mothers smoked during pregnancy had lower beat-to-beat heart rate variability in quiet sleep. Infants whose mothers consumed alcohol had lower global heart rate variability, but only in active sleep. Unexposed infants demonstrated increases in heart rate with head-up tilt and decreases in heart rate with head-down tilt, but smoking and alcohol-exposed infants showed no significant responses. These results indicate that autonomic function is altered by prenatal exposure to alcohol and smoking. Such markers may provide early identification of infants at greatest risk for SIDS. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 234,242, 2009 [source]

    Morphometric analysis and tectonic interpretation of digital terrain data: a case study

    EARTH SURFACE PROCESSES AND LANDFORMS, Issue 8 2003
    Gyozo Jordan
    Abstract Tectonic movement along faults is often re,ected by characteristic geomorphological features such as linear valleys, ridgelines and slope-breaks, steep slopes of uniform aspect, regional anisotropy and tilt of terrain. Analysis of digital elevation models, by means of numerical geomorphology, provides a means of recognizing fractures and characterizing the tectonics of an area in a quantitative way. The objective of this study is to investigate the use of numerical geomorphometric methods for tectonic geomorphology through a case study. The methodology is based on general geomorphometry. In this study, the basic geometric attributes (elevation, slope, aspect and curvatures) are complemented with the automatic extraction of ridge and valley lines and surface speci,c points. Evans' univariate and bivariate methodology of general geomorphometry is extended with texture (spatial) analysis methods, such as trend, autocorrelation, spectral, and network analysis. Terrain modelling is implemented with the integrated use of: (1) numerical differential geometry; (2) digital drainage network analysis; (3) digital image processing; and (4) statistical and geostatistical analysis. Application of digital drainage network analysis is emphasized. A simple shear model with principal displacement zone with an NE,SW orientation can account for most of the the morphotectonic features found in the basin by geological and digital tectonic geomorphology analyses. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Spatial patterns of water surface topography at a river confluence

    EARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2002
    Dr Pascale M. Biron
    Abstract Understanding flow structures in river confluences has largely been the product of interpretations made from measured flow velocity data. Here, we turn the attention to the investigation of the patterns of both the average and standard deviations of the micro-topography of the water surface at an asymmetrical natural discordant confluence for different flow conditions. Water surface topography is measured using a total station to survey the position of a reflector mounted on a custom-built raft. To limit error problems related to changes in the water level, measurements are taken and analysed by cross-stream transects where five water surface profiles are taken before moving to the next transect. Three-dimensional numerical simulations of the flow dynamics at the field site are used to examine predicted water surface topography for a steady-state situation. The patterns are interpreted with respect to flow structure dynamics, visual observations of boils, and bed topography. Results indicate that coherent patterns emerge at the water surface of a discordant bed confluence for different flow conditions. The zone of stagnation and the mixing layer are characterized by super-elevation, a lateral tilt is present at the edge of the mixing layer, and a zone of super-elevation is present on the tributary side at the downstream junction corner. The latter seems associated with periodical upwelling and is not present in the numerical simulations that do not take into account instantaneous velocity fluctuations. Planform curvature, topographic steering related to the tributary mouth bar, and turbulent structures associated with the mixing layer all play a key role in the pattern of both the average and standard deviation of the water surface topography at confluences. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Analysis of a radiographic technique for measurement of equine metacarpal bone shape

    EQUINE VETERINARY JOURNAL, Issue S33 2001
    L. J. WALTER
    Summary Accuracy and limitations of a radiographic technique were established for measurement of metacarpal bone shape in horses. A radiographic index (RI) has been used to measure changes in third metacarpal (Mc3) bone shape in response to training in young racehorses. The aim of these experiments was to determine the effects of positioning of the radiographic equipment on RI measurements from lateromedial radiographs of a left ex vivo metacarpus. Repeatability of the RI measurement in left lateromedial and right mediolateral view Mc3s were evaluated. The width of the dorsal cortex (DC), palmar cortex (PC) and medulla (M) were measured at a position 25 mm distal to the nutrient foramen and the RI calculated where RI = [(DC+PC)/M] x [DC/PC]. The reference RI values were obtained from 12 standard lateromedial radiographs. Factors analysed included the optimum focus-object distance, the angle at which the x-ray machine was positioned, the distance of the cassette from the limb, and the horizontal angle and vertical tilt of the cassette. The RI values included within the confidence interval (mean ° 1.96 x s.d.) were considered sufficiently accurate. The optimum focus-object distance was 1 m. Accurate measurements were obtained when the cassette was held as close to the limb as possible with the horizontal angle not exceeding 5°. The x-ray machine needed to be orientated within 6° of the lateromedial plane. These findings suggest that the radiographic index can be used to measure Mc3 bone shape, providing there is accurate alignment of the x-ray machine, cassette, and limb, with respect to one another. [source]

    The Performance of Characteristics-based Indices1

    EUROPEAN FINANCIAL MANAGEMENT, Issue 2 2009
    Noël Amenc
    G11; G12 Abstract This paper analyses a set of characteristics-based indices that, it has been argued, outperform market cap-weighted indices. We analyse the performance of an exhaustive list of these indices and show that i) the outperformance over value-weighted indices may be negative over long time periods, and ii) there is no significant outperformance over equal-weighted indices. An analysis of the style and sector exposures of characteristics-based indices reveals a significant value tilt. When this tilt is properly adjusted for, the abnormal returns of these indices decrease considerably. Moreover, it is straightforward to construct portfolios with higher Sharpe ratios than characteristics-based indices through factor or sector tilts. [source]

    Abnormal cardiovascular responses to carotid sinus massage also occur in vasovagal syncope , implications for diagnosis and treatment

    EUROPEAN JOURNAL OF NEUROLOGY, Issue 8 2010
    A. M. Humm
    Background and purpose:, Carotid sinus massage (CSM) is commonly used to identify carotid sinus hypersensitivity (CSH) as a possible cause for syncope, especially in older patients. However, CSM itself could provoke classical vasovagal syncope (VVS) in pre disposed subjects. Methods:, Retrospective analysis of CSM, cardiovascular autonomic function tests (including tilt table testing) and medical history in 388 patients with recurrent syncope to identify and characterize patients in whom an abnormal response to CSM was more likely to reflect VVS than CSH. Results:, CSM was abnormal in 79 patients. In 53 patients (77.2 ± 8.7 years), CSH was the likely cause of syncope. VVS was the more likely diagnosis in 26 younger patients (59.7 ± 12.6 years) with longstanding syncope from youth, in whom fear or pain was as a trigger; 7/26 suffered from intense chronic or intermittent neck pain and one exacerbation of syncopal attacks followed a physical and emotional trauma to the neck. In VVS, 4/26 had spontaneous VVS during head-up tilt, another six after venepuncture (performed in 17/26). In 6/26, the abnormal response to CSM was delayed, occurring 62.8 ± 28.4 s after completion of CSM. The response to CSM was predominantly of the mixed type (20/26) and abnormal on both sides in 14/26. Conclusions:, An abnormal response to CSM may not indicate syncope caused by CSH and needs to be considered in the light of the patient's age, duration of syncopal episodes and detailed history of provocative stimuli. Differentiating CSH from VVS with an abnormal response to CSM has various implications from advice on driving to treatment strategies. [source]

    Control of eye orientation: where does the brain's role end and the muscle's begin?

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2004
    Dora E. Angelaki
    Abstract Our understanding of how the brain controls eye movements has benefited enormously from the comparison of neuronal activity with eye movements and the quantification of these relationships with mathematical models. Although these early studies focused on horizontal and vertical eye movements, recent behavioural and modelling studies have illustrated the importance, but also the complexity, of extending previous conclusions to the problems of controlling eye and head orientation in three dimensions (3-D). An important facet in understanding 3-D eye orientation and movement has been the discovery of mobile, soft-tissue sheaths or ,pulleys' in the orbit which might influence the pulling direction of extraocular muscles. Appropriately placed pulleys could generate the eye-position-dependent tilt of the ocular rotation axes which are characteristic for eye movements which follow Listing's law. Based on such pulley models of the oculomotor plant it has recently been proposed that a simple two-dimensional (2-D) neural controller would be sufficient to generate correct 3-D eye orientation and movement. In contrast to this apparent simplification in oculomotor control, multiple behavioural observations suggest that the visuo-motor transformations, as well as the premotor circuitry for saccades, pursuit eye movements and the vestibulo-ocular reflexes, must include a neural controller which operates in 3-D, even when considering an eye plant with pulleys. This review summarizes the most recent work and ideas on this controversy. In addition, by proposing directly testable hypotheses, we point out that, in analogy to the previously successful steps towards elucidating the neural control of horizontal eye movements, we need a quantitative characterization first of motoneuron and next of premotor neuron properties in 3-D before we can succeed in gaining further insight into the neural control of 3-D motor behaviours. [source]

    The effect of whole-body tilt on sound lateralization

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2002
    Jörg Lewald
    Abstract The effect of passive whole-body tilt in the frontal plane on the lateralization of dichotic sound was investigated in human subjects. Pure-tone pulses (1 kHz, 100 ms duration) with various interaural time differences were presented via headphones while the subject was in an upright position or tilted 45° or 90° to the left or right. Subjects made two-alternative forced-choice (left/right) judgements on the intracranial sound image. During body tilt, the auditory median plane of the head, computed from the resulting psychometric functions, was always shifted to the upward ear, indicating a shift of the auditory percept to the downward ear, that is, in the direction of gravitational linear acceleration. The mean maximum magnitude of the auditory shift obtained with 90° body tilt was 25 µs. On the one hand, these findings suggest a certain influence of the otolith information about body position relative to the direction of gravity on the representation of auditory space. However, in partial contradiction to previous work, which had assumed existence of a significant ,audiogravic illusion', the very slight magnitude of the present effect rather reflects the excellent stability in the neural processing of auditory spatial cues in humans. Thus, it might be misleading to use the term ,illusion' for this quite marginal effect. [source]

    Reliability of orthostatic responses in healthy men aged between 65 and 75 years

    EXPERIMENTAL PHYSIOLOGY, Issue 4 2005
    Tim J. Gabbett
    The purpose of this study was to investigate the short-, medium- and long-term reproducibility of cardiovascular responses during 90° head-up tilt (HUT) in healthy older men. Twenty-eight healthy male subjects aged 69 (95% confidence intervals, 68,70) years participated in the study. Eight subjects underwent duplicate 90° HUT tests on consecutive days, while 20 subjects underwent four 90° HUT tests performed at baseline, and after 1 week, 1 month and 1 year. Following a 20-min supine resting period, each subject was rapidly tilted to the upright vertical position (90° HUT) and remained in that position for 15 min. Beat-by-beat recordings of mean (MAP), systolic (SBP) and diastolic (DBP) pressures were made via Finapres, while heart rate (HR) was monitored continuously from an electrocardiogram. No significant test,retest differences (P > 0.05) were observed for the changes in HR, MAP, SBP or DBP during 90° HUT. These measurements demonstrated high reproducibility (intraclass correlation coefficient, r= 0.91,0.99, P < 0.05). The supine resting and tilted HR, MAP, SBP and DBP over the 1-week, 1-month and 1-year period were not significantly different (P > 0.05) from baseline, and demonstrated high reproducibility (intraclass correlation coefficient, r= 0.82,0.98, P < 0.05). The results of this study demonstrate that in healthy older men, cardiovascular responses during orthostasis are highly reproducible, and this reproducibility is maintained over a 12-month period. These findings demonstrate that the 90° HUT test offers a reproducible method of monitoring longitudinal orthostatic responses in healthy older men. [source]

    Style timing with the value spread in Australia

    ACCOUNTING & FINANCE, Issue 4 2009
    Charles E. Hyde
    G11; G33 Abstract The value spread is shown to be positively related to the value premium in the Australian market. The relationship is especially strong for small cap portfolios and typically stronger when using the book-to-price ratio than other value metrics. In small cap portfolios, the positive value premium,spread relationship is primarily driven by the short side. Our results are consistent with previous findings in US and Asian markets. We also show that the small cap,large cap value spread differential is positively related to the corresponding value premium differential, suggesting the value spread can also be used for timing the large/small cap tilt. [source]

    The Ohalo II prehistoric camp (19.5 Ky): New evidence for environmental and tectonic changes at the Sea of Galilee

    GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 5 2002
    Shmuel Belitzky
    Combined archaeological data, shore surveys, and aerial photos of submerged sediments in the Sea of Galilee provide new insights into environmental and tectonic events, their dating, and their impact on the Ohalo II prehistoric camp (ca. 19,500 yr B.P.) and its surroundings. The Ohalo II waterlogged campsite contains excellently preserved brush hut remains and other in situ features, all embedded in late Pleistocene lacustrine strata. The findings indicate relatively short occupation of the site, not more than months or several years at a time. The high quality in situ preservation of delicate organic materials, as well as the short occupation period, suggests a quick and gentle burial by fine sediments. The evident fast submergence (water level rise of the Sea of Galilee) could have been the result of climatic fluctuations towards the end of the last glaciation and/or small-scale tectonic subsidence. The site is located on a tectonic block formed in the western fault belt of the Dead Sea Rift. We present new evidence of post-occupational folding of the late Pleistocene strata and recent tilting and faulting. A westward tectonic tilt may have caused the blockage of the old Jordan River outlet after A. D. 1106. Excellent preservation of the fault traces to the east of the site is attributed to the young age of the displacement on the fault. The last displacement apparently post-dates the blockage of the old Jordan River. © 2002 Wiley Periodicals, Inc. [source]

    Migration velocity analysis for tilted transversely isotropic media

    GEOPHYSICAL PROSPECTING, Issue 1 2009
    Laxmidhar Behera
    ABSTRACT Tilted transversely isotropic formations cause serious imaging distortions in active tectonic areas (e.g., fold-and-thrust belts) and in subsalt exploration. Here, we introduce a methodology for P-wave prestack depth imaging in tilted transversely isotropic media that properly accounts for the tilt of the symmetry axis as well as for spatial velocity variations. For purposes of migration velocity analysis, the model is divided into blocks with constant values of the anisotropy parameters , and , and linearly varying symmetry-direction velocity VP0 controlled by the vertical (kz) and lateral (kx) gradients. Since determination of tilt from P-wave data is generally unstable, the symmetry axis is kept orthogonal to the reflectors in all trial velocity models. It is also assumed that the velocity VP0 is either known at the top of each block or remains continuous in the vertical direction. The velocity analysis algorithm estimates the velocity gradients kz and kx and the anisotropy parameters , and , in the layer-stripping mode using a generalized version of the method introduced by Sarkar and Tsvankin for factorized transverse isotropy with a vertical symmetry axis. Synthetic tests for several models typical in exploration (a syncline, uptilted shale layers near a salt dome and a bending shale layer) confirm that if the symmetry-axis direction is fixed and VP0 is known, the parameters kz, kx, , and , can be resolved from reflection data. It should be emphasized that estimation of , in tilted transversely isotropic media requires using nonhyperbolic moveout for long offsets reaching at least twice the reflector depth. We also demonstrate that application of processing algorithms designed for a vertical symmetry axis to data from tilted transversely isotropic media may lead to significant misfocusing of reflectors and errors in parameter estimation, even when the tilt is moderate (30°). The ability of our velocity analysis algorithm to separate the anisotropy parameters from the velocity gradients can be also used in lithology discrimination and geologic interpretation of seismic data in complex areas. [source]

    Thickness-Dependent Structural Evolutions and Growth Models in Relation to Carrier Transport Properties in Polycrystalline Pentacene Thin Films,

    ADVANCED FUNCTIONAL MATERIALS, Issue 17 2007
    H.-L. Cheng
    Abstract Thickness-dependent crystal structure, surface morphology, surface energy, and molecular structure and microstructure of a series of polycrystalline pentacene films with different film thickness ranging from several monolayers to the several hundred nanometers have been investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), contact angle meter, and Raman spectroscopy. XRD studies indicate that thin film polymorphs transformation behaviours are from the orthorhombic phase to the thin-film phase and then to the triclinic bulk phase as measured by the increased tilt angle (,tilt) of the pentacene molecule from the c- axis toward the a- axis. We propose a growth model that rationalizes the ,tilt increased along with increasing film thickness in terms of grain size and surface energy varying with film growth using AFM combined with contact angle measurements. The vibrational characterizations of pentacene molecules in different thickness films were investigated by Raman spectroscopy compared to density functional theory calculations of an isolated molecule. In combination with XRD and AFM the method enables us to distinguish the molecular microstructures in different thin film polymorphs. We proposed a methodology to probe the microscopic parameters determining the carrier transport properties based on Davydov splitting and the characteristics of aromatic C,C stretching modes in Raman spectra. When compared to the triclinic bulk phase at a high thickness, we suggest that the first few monolayer structures located at the dielectric surface could have inferior carrier transport properties due to weak intermolecular interactions, large molecular relaxation energy, and more grain boundaries. [source]

    Multi-objective optimization of the coal combustion performance with artificial neural networks and genetic algorithms

    INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 6 2005
    Hao Zhou
    Abstract The present work introduces an approach to predict the nitrogen oxides (NOx) emissions and carbon burnout characteristics of a large capacity pulverized coal-fired boiler with an artificial neural network (ANN). The NOx emissions and carbon burnout characteristics are investigated by parametric field experiments. The effects of over-fire-air (OFA) flow rates, coal properties, boiler load, air distribution scheme and nozzle tilt are studied. An ANN is used to model the NOx emissions characteristics and the carbon burnout characteristics. A genetic algorithm (GA) is employed to perform a multi-objective search to determine the optimum solution of the ANN model, finding the optimal setpoints, which can suggest operators' correct actions to decrease NOx emissions and the carbon content in the flyash simultaneously, namely, get a good boiler combustion performance with high boiler efficiency while keeping the NOx emission concentration meet the requirement. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Aspect graphs for three-dimensional object recognition machine vision systems

    INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 1 2005
    Tatiana Tambouratzis
    The purpose of this research is to seek evidence for viewer-centered (especially aspect-graph-based) visual processing in the elementary task of object understanding. Two homologous, bilaterally symmetrical three-dimensional (3-D) objects have been employed that differ in that one is based on parts with flat surfaces and the other on parts with curved surfaces. The following procedure has been followed, separately for each object. In the training (saturated free inspection and manipulation) phase, a location (identical for both objects) of the object is marked with a red strip and the subjects' task is to memorize the object structure as well as the position of the strip. In the test phase, two-dimensional views of the object without the strip are presented and the subjects' task is to determine whether the previously marked location should be visible or invisible in the particular view. Findings have been found consistent with an aspect-graph-based 3-D object representation: (a) the reaction times and errors show characteristic dependencies on viewpoint; (b) a number of views (corresponding to certain aspects and aspect transitions of the aspect graph) consistently produce faster and more accurate recognition; (c) the differences in the aspect graphs of the two objects are reflected in differing patterns of reaction times and errors; furthermore; (d) the subjects impose a standard orientation on the objects, whereby a strong inversion effect is observed; and (e) performance varies in a similar way for both objects as a function of tilt. It is concluded that object understanding is viewpoint dependent, that is, based on a number of views. The characteristics of the views found to be most important for object understanding can be employed for creating efficient 3-D object recognition machine vision systems. © 2005 Wiley Periodicals, Inc. Int J Int Syst 20: 47,72, 2005. [source]

    Relationship between stroke volume, cardiac output and filling of the heart during tilt

    ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2009
    M. BUNDGAARD-NIELSEN
    Background: Cardiac function curves are widely accepted to apply to humans but are not established for the entire range of filling of the heart that can be elicited during head-up (HUT) and head-down tilt (HDT), taken to represent minimal and maximal physiological filling of the heart, respectively. With the supine resting position as a reference, we assessed stroke volume (SV), cardiac output (CO) and filling of the heart during graded tilt to evaluate whether SV and CO are maintained during an assumed maximal physiological filling of the heart elicited by 90° HDT in healthy resting humans. Methods: In 26 subjects, central blood volume was manipulated with graded tilt from 60° HUT to 90° HDT. We measured SV, CO (Finometer®) and cardiac filling by echocardiography of the left ventricular end-diastolic volume (LVEDV; n=12). Results: From supine rest to 60° HUT, SV and CO decreased 23 ml [confidence intervals (CI): 16,30; P<0.001; 23%] and 0.9 l/min (0.4,1.4; P<0.0001; 14%), respectively, but neither SV nor CO changed during HDT up to 70°. However, during 90° HDT, SV decreased 12 ml (CI: 6,19; P<0.0001; 12%), with an increase of 21 ml (9,33; P=0.002; 16%) in LVEDV because HR increased 3 bpm and CO decreased 0.5 l/min (ns). Conclusion: This study confirmed that SV and CO are maximal in resting, supine, healthy humans and decrease during HUT. However, 90° HDT was associated with increased LVEDV and induced a reduction in SV. [source]

    Single-Stage Adenosine Tilt Testing in Patients with Unexplained Syncope

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2004
    SUNEET MITTAL M.D.
    Introduction: We previously have shown that a 3-minute single-stage adenosine tilt test has a diagnostic yield comparable to a two-stage protocol consisting of a 30-minute drug-free tilt followed by a 15-minute isoproterenol tilt. In this study, we sought to further define the clinical utility of adenosine tilt testing in patients with unexplained syncope by prospectively evaluating test specificity and determining predictors of a positive test response. Methods and Results: The specificity of single-stage adenosine tilt testing was determined using 30 control subjects. To determine the diagnostic yield of this protocol, adenosine tilts were performed in 129 patients with unexplained syncope. The adenosine tilt test protocol had high specificity (100%) but a low overall diagnostic yield (18%). However, the yield was affected significantly by age. In patients ,40 years of age, the tilt test was positive in 15 (41%) of 37 patients, which was significantly greater than the yield in patients between the ages of 41 and 64 years (6/41 patients [15%], P = 0.012) and those ,65 years of age (2/41 patients [5%], P < 0.0001). Conclusion: These data support single-stage adenosine tilt testing in patients ,40 years of age because the diagnostic yield of the test is maximal in this group and the test can be completed in ,3 minutes. Conversely, the diagnostic yield of adenosine tilt testing in patients >40 years of age is low, suggesting that the clinical utility of this protocol is limited in these patients. (J Cardiovasc Electrophysiol, Vol. 15, pp. 1-4, June 2004) [source]

    Defibrillation Efficacy and Pain Perception of Two Biphasic Waveforms for Internal Cardioversion of Atrial Fibrillation

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2003
    Jens Jung M.D.
    Introduction: We evaluated the influence of the peak voltage of waveforms used for internal cardioversion of atrial fibrillation on defibrillation efficacy and pain perception. A low peak voltage biphasic waveform generated by a 500-,F capacitor with 40% tilt was compared to a standard biphasic waveform generated by a 60-,F capacitor with 80% tilt. Methods and Results: In 19 patients with paroxysmal atrial fibrillation (79% male, age 55 ± 11 years, 21% with heart disease), the atrial defibrillation threshold (ADFT) was determined during deep sedation with midazolam for both waveforms in a randomized fashion using a step-up protocol. Internal cardioversion with a single lead (shock vector: coronary sinus to right atrium) was successful in 18 (95%) of 19 patients. ADFT energy and peak voltage were significantly lower for the low-voltage waveform (2.1 ± 2.4 J vs 3.5 ± 3.9 J, P < 0.01; 100 ± 53 V vs 290 ± 149 V, P < 0.01). Sedation then was reversed with flumazenil after ADFT testing. Two shocks at the ADFT (or a 3-J shock if ADFT >3 J) were administered to the patient using each waveform in random order. Pain perception was assessed using both a visual scale and a numerical score. ADFTs were above the pain threshold in 17 (94%) of 18 patients, even though the ADFT with the 500-,F waveform was <100 V in 63% of the patients. Pain perception was comparable for both waveforms (numerical score: 6.5 ± 2.4 vs 6.3 ± 2.6; visual scale: 5.4 ± 2.6 vs 5.2 ± 3.1; P = NS, 500-,F vs 60-,F). The second shock was perceived as more painful in 88% of the patients, independent of the waveform used. Conclusion: Despite a 66% lower peak voltage and a 40% lower energy, the 40% tilt, 500-,F capacitor biphasic waveform did not change the pain perceived by the patient during delivery of internal cardioversion shocks. Pain perception for internal cardioversion probably is not influenced by peak voltage alone and increases with the number of applied shocks. (J Cardiovasc Electrophysiol, Vol. 14, pp. 837-840, August 2003) [source]

    New Approach to Biphasic Waveforms for Internal Defibrillation:

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2000
    Fully Discharging Capacitors
    Internal Defibrillation with Fully Discharging Capacitors. Introduction: The use of two independent, fully discharging capacitors for each phase of a biphasic defibrillation waveform may lead to the design of a simpler, smaller, internal defibrillator. The goal of this study was to determine the optimal combination of capacitor sizes for such a waveform. Methods and Results: Eight full-discharge (95/95% tilt), biphasic waveforms produced by several combinations of phase-1 capacitors (30, 60, and 90 ,F) and phase-2 capacitors (1/3, 2/3, and 1.0 times the phase-1 capacitor) were tested and compared to a single-capacitor waveform (120 ,F, 65/65% tilt) in a pig ventricular fibrillation model (n = 12, 23 ± 2 kg). In the full-discharge waveforms, phase-2 peak voltage was equal to phase-1 peak voltage. Shocks were delivered between a right ventricular lead and a left pectoral can electrode. E50s and V50s were determined using a ten-step Bayesian process. Full-discharge waveforms with phase-2 capacitors of ,40 ,F had the same E50 (6.7 ± 1.7 J to 7.3 ± 3.9 J) as the single-capacitor truncated waveform (7.3 ± 3.7 J), whereas waveforms with phase-2 capacitors of ,60 ,F had an extremely high E50 (14.5 ± 10.8 J or greater, P < 0.05). Moreover, of the former set of energy-efficient waveforms, those with phase-1 capacitors of ,60 ,F additionally exhibited V50s that were equivalent to the V50 of the single-capacitor waveform (344 ± 65 V to 407 ± 50 V vs 339 ± 83 V). Conclusion: Defibrillation efficacy can be maintained in a full-discharge, two-capacitor waveform with the proper choice of capacitors. [source]

    Respiratory Changes in Vasovagal Syncope

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2000
    ARVINDER S. KURBAAN M.D.
    Respiratory Changes in Vasovagal Syncope. introduction: Respiratory changes accompany the cardiovascular changes during head-up. tilt test-induced vasovagal syncope. Methods and Results: Using the 45-minute 60° head-up Westminster protocol, 29 patients were studied (mean age 53.9 ± 20.0 years; 19 females). Two groups resulted: tilt-induced vasovagal syncope positive and negative. The cardiorespiratory parameters blood pressure (BP), heart rate (HR), tidal volume, and minute volume were measured. Comparisons of the cardiorespiratory parameters were made within the positive group and negative group, and then between the two groups. There were 14 in the positive group and 15 in the negative group. Baseline measurements were normalized to 1.0. Comparing the late tilt periods between the positive and negative groups, there were differences in BP (P < 0.002), HR (P < 0.002), tidal volume (P < 0.05), and minute volume (P < 0.002). In the positive group comparing early with late intervals: BP l.11 ± 0.09 versus 0.49 ± 0.17, P < 0.0001; HR 1.18 ± 0.12 versus 0.85 ±0.35, P < 0.009; tidal volume 1.39 ± 0.34 versus 2.17 ± 1.00, P < 0.015; and minute volume 1.24 ± 0.26 versus 3.3 ± 2.03, P < 0.0025. There were no comparable cardiorespiratory changes in the negative group. Conclusion: There were significant differences in the respiratory and cardiovascular parameters measured between those who were positive and those who were negative for tilt-induced vasovagal syncope. Within the positive group, in addition to the falls in HR and BP, there were significant increases in minute volume and tidal volume during late tilt. This suggests that there may be a role for respiratory sensors in vasovagal syncope that may permit earlier and hence possibly more effective therapy for selected patients. [source]

    Charge transport in stacking metal and metal-free phthalocyanine iodides.

    JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 13 2009
    Effects of packing, central metals, core modification, dopants, external electric field, substitutions
    Abstract The charge-transport properties of the one-dimensional stacking metal phthalocyanine iodides (M(Pc)I, M = Fe, Co, Ni, Cu) and metal-free phthalocyanine iodide (H2(Pc)I) have been theoretically investigated. On the basis of the tight-binding approximation and two-state theory, both the site-energy corrected energy splitting in dimer and Fock-matrix-based methods are used to calculate the transfer integral. The intermolecular motions, including interplanar translation, rotation, slip, and tilt, exert remarkable impacts on the transfer integral. The order/disorder of the dopant stack and the long-range electrostatic interactions are also demonstrated to be crucial factors for modulation of charge-transport properties. The transfer integral undergoes slight changes under an applied electric field along the stacking direction in the range of 106 , 107 V cm,1. The change of central metals in MPc has little effect on the transfer integrals, but significantly affects the reorganization energies. The extension of the ,-conjugation in macrocyclic ligand brings about considerable influence on the transfer integrals. Peripheral substitutions by animo, hydroxyl, and methyl lead to deviations from planarity of macromolecular rings, and hence affect the valence bands significantly. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009 [source]

    Tl(I)-the strongest structure-breaking metal ion in water?

    JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 6 2007
    A quantum mechanical/molecular mechanical simulation study
    Abstract Structural and dynamical properties of the Tl(I) ion in dilute aqueous solution have been investigated by ab initio quantum mechanics in combination with molecular mechanics. The first shell plus a part of the second shell were treated by quantum mechanics at Hartree-Fock level, the rest of the system was described by an ab initio constructed potential. The radial distribution functions indicate two different bond lengths (2.79 and 3.16 Å) in the first hydration shell, in good agreement with large-angle X-ray scattering and extended X-ray absorption fine structure spectroscopy results. The average first shell coordination number was found as 5.9, and several other structural parameters such as coordination number distributions, angular distribution functions, and tilt- and ,-angle distributions were evaluated. The ion,ligand vibration spectrum and reorientational times were obtained via velocity auto correlation functions. The TlO stretching force constant is very weak with 5.0 N m,1. During the simulation, numerous water exchange processes took place between first and second hydration shell and between second shell and bulk. The mean ligand residence times for the first and second shell were determined as 1.3 and 1.5 ps, respectively, indicating Tl(I) to be a typical "structure-breaker". The calculated hydration energy of ,84 ± 16 kcal mol,1 agrees well with the experimental value of ,81 kcal mol,1. All data obtained for structure and dynamics of hydrated Tl(I) characterize this ion as a very special case among all monovalent metal ions, being the most potent "structure-breaker", but at the same time forming a distinct second hydration shell and thus having a far-reaching influence on the solvent structure. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007 [source]

    Using real-time MRI to quantify altered joint kinematics in subjects with patellofemoral pain and to evaluate the effects of a patellar brace or sleeve on joint motion

    JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2009
    Christine E. Draper
    Abstract Abnormal patellofemoral joint motion is a possible cause of patellofemoral pain, and patellar braces are thought to alleviate pain by restoring normal joint kinematics. We evaluated whether females with patellofemoral pain exhibit abnormal patellofemoral joint kinematics during dynamic, weight-bearing knee extension and assessed the effects of knee braces on patellofemoral motion. Real-time magnetic resonance (MR) images of the patellofemoral joints of 36 female volunteers (13 pain-free controls, 23 patellofemoral pain) were acquired during weight-bearing knee extension. Pain subjects were also imaged while wearing a patellar-stabilizing brace and a patellar sleeve. We measured axial-plane kinematics from the images. Females with patellofemoral pain exhibited increased lateral translation of the patella for knee flexion angles between 0°and 50° (p,=,0.03), and increased lateral tilt for knee flexion angles between 0° and 20° (p,=,0.04). The brace and sleeve reduced the lateral translation of the patella; however, the brace reduced lateral displacement more than the sleeve (p,=,0.006). The brace reduced patellar tilt near full extension (p,=,0.001), while the sleeve had no effect on patellar tilt. Our results indicate that some subjects with patellofemoral pain exhibit abnormal weight-bearing joint kinematics and that braces may be effective in reducing patellar maltracking in these subjects. Published by Wiley Periodicals, Inc. J Orthop Res 27: 571,577, 2009 [source]

    Solid-supported amphiphilic triblock copolymer membranes grafted from gold surface

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2009
    Ekaterina Rakhmatullina
    Abstract Gold-supported amphiphilic triblock copolymer brushes composed of two hydrophilic poly(2-hydroxyethyl methacrylate) (PHEMA) blocks and a hydrophobic poly(n -butyl methacrylate) (PBMA) middle part were synthesized using a surface-initiated ATRP. Attenuated total reflectance Fourier transform infrared spectroscopy, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), ellipsometry, contact angle measurements, and atomic force microscopy were used for the characterization of PHEMA- co -PBMA- co -PHEMA brushes. The PM-IRRAS analysis revealed an increase of the chain tilt toward the gold surface during growth of the individual blocks. We suggest that the orientation of the amphiphilic polymer brushes is influenced by both the chain length and the interchain interactions. Additionally, a detachment of the polymer membranes from the solid support and subsequent gel permeation chromatography analyses allowed us to establish their compositions. We applied block-selective solvents (water and hexane) as well as a good solvent for the whole polymer chain (ethanol) to study the morphology and solvent responsive behavior of the amphiphilic brushes. The presented results could serve as a good starting point for the fabrication of functional solid-supported membranes for biosensing applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1,13, 2009 [source]