Home About us Contact
|
Home About us Contact | ||
|
|
||
Two-dimensional
Terms modified by Two-dimensional Selected AbstractsObserver Variation in the Echocardiographic Measurement of Maximum Atrial Septal Excursion: A Comparison of M-Mode with Two-Dimensional or Transesophageal EchocardiographyECHOCARDIOGRAPHY, Issue 10 2009Background: Atrial septal aneurysm is typically diagnosed by transthoracic two-dimensional or transesophageal echocardiography (2DE or TEE). Such techniques are highly dependent on visual inspection which predisposes to observer variation. This study compares inter- and intraobserver variations in the measurement of maximum atrial septal excursion (MASE) obtained using transthoracic M-mode echocardiography (MME) with that obtained using 2DE or TEE. Methods: Consecutive patients with highly mobile atrial septal motion by visual inspection during 2DE or TEE were studied. MASE was estimated visually on 2DE or TEE. MME tracings were obtained with the cursor bisecting the parabola formed by the atrial septum at its maximum deviation from the midline. Electronic calipers were used to measure MASE for all echocardiographic techniques. Two observers provided two measurements each. Observer variation was determined by assessing standard deviation and confidence intervals of inter- and intraobserver differences. Results: Interobserver analysis showed standard deviations of 0.077 cm (95% CI 0.065,0.094) for MME and 0.280 cm (95% CI 0.242,0.334) for 2DE or TEE. Intraobserver analysis showed standard deviations of 0.08 cm (95% CI 0.068,0.101) for MME and 0.318 cm (95% CI 0.274,0.381) for 2DE or TEE. The mean magnitude of measured MASE was 0.44 cm higher with MME than with 2DE or TEE (95% CI 0.068,0.101). Conclusions: MME assessment of MASE is associated with substantially lower inter- and intraobserver variation than 2DE or TEE assessment. The magnitude of MASE is substantially higher with MME than with 2DE or TEE. [source] A Two-Dimensional, Hydrogen-Bond-Cross-Linked Molybdenum(VI) Network Polymer with Catalytic ActivityEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2007Yi Luan Abstract The new hybrid inorganic,organic polymer [MoO2Cl2(H2O)2]·(H2dipy-pra)Cl2 (1), where dipy-pra = 1,3-bis(4-pyridyl)propane, has been synthesized and crystallographically characterized. MoO2Cl2(H2O)2 and the [H2dipy-pra]2+ cation are cross-linked by Mo,H2O···Cl and H2dipy-pra···Cl hydrogen bonds to form a two-dimensional layer structure. Complex 1 is an efficient catalyst, with H2O2 as the oxygen-source oxidant and NaHCO3 as the cocatalyst, in the epoxidation of olefinic compounds under ambient conditions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Investigation of Fluid and Coarse-Particle Dynamics in a Two-Dimensional Spouted BedCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2004T. Swasdisevi Abstract The aerodynamics of particles and gas flow in a two-dimensional spouted bed (2DSB) with draft plates is investigated with the aid of the discrete element method. The geometry of the 2DSB with draft plates is set as close as possible to the experimental apparatus of Kudra [1] and Kalwar [2]. The physical properties of the coarse particles are similar to those of shelled corn. The calculated minimum spouting velocity and pressure drop agree well with the correlations of Kudra [1] and Kalwar [2]. In the spout region, the particle vertical velocities are found to decrease as the height increases. The fluid velocity in the downcomer region decreases as the superficial gas velocity increases. The particle circulation rate increases when the friction coefficient decreases or the separation height increases. At the minimum spouting velocity, the bed height does not affect the particle circulation rate in the 2DSB with draft plates. The draft plates not only reduce the minimum spouting velocity and pressure drop but also increase the maximum spoutable bed height. The effect of taking out the draft plates on the spouting phenomenon is investigated and the effect of putting in a deflector on the possible breakage of the particles is also estimated. [source] ChemInform Abstract: EuSnP: A Novel Antiferromagnet with Two-Dimensional, Corrugated Sn Sheets.CHEMINFORM, Issue 33 2002Amy C. Payne Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 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] Influence of dT20 and [d(AT)10]2 on Cisplatin Hydrolysis Studied by Two-Dimensional [1H,15N] HMQC NMR SpectroscopyCHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2005Jo Vinje Dr. Abstract The influence of the presence of DNA on the kinetics of cisplatin (cis -[PtCl2(NH3)2]) aquation (replacement of Cl, by H2O) and anation (replacement of H2O by Cl,) involved in the hydrolysis of cisplatin have been determined by two-dimensional [1H,15N] HMQC NMR spectroscopy. Single-stranded dT20 and double-stranded [d(AT)10]2 oligonucleotides were used as DNA models, avoiding guanines which are known to react rapidly with aquated cisplatin forms. Reactions starting from cis -[PtCl2(15NH3)2], or from a stoichiometric mixture of cis -[Pt(15NH3)2(H2O)2]2+ and Cl, (all 0.5,mM PtII; in ionic strength, adjusted to 0.095,M or 0.011,M with NaClO4, pH between 3.0 and 4.0) were followed in an NMR tube in both the absence and presence of 0.7,mM dT20 or [d(AT)10]2. In the presence of dT20, we observed a slight and ionic-strength-independent decrease (15,20,%) of the first aquation rate constant, and a more significant decrease of the second anation rate constant. The latter was more important at low ionic strength, and can be explained by efficient condensation of cis -[Pt(15NH3)2(H2O)2]2+ on the surface of single-stranded DNA, in a region depleted of chloride anions. At low ionic strength, we observed an additional set of [1H,15N] HMQC spectral signals indicative of an asymmetric species of PtN2O2 coordination, and we assigned them to phosphate-bound monoadducts of cis -[Pt(15NH3)2(H2O)2]2+. Double-stranded [d(AT)10]2 slowed down the first aquation step also by approximately 15,%; however, we could not determine the influence on the second hydrolysis step because of a significant background reaction with cis -[Pt(NH3)2(H2O)2]2+. [source] Impact of a rock avalanche on a moraine-dammed proglacial lake: Laguna Safuna Alta, Cordillera Blanca, PeruEARTH SURFACE PROCESSES AND LANDFORMS, Issue 10 2005Bryn Hubbard Abstract Moraines that dam proglacial lakes pose an increasing hazard to communities in the Andes and other mountain ranges. The moraines are prone to failure through collapse, overtopping by lake waters or the effect of displacement waves resulting from ice and rock avalanches. Resulting floods have led to the loss of thousands of lives in the Cordillera Blanca mountains of Peru alone in the last 100 years. On 22 April 2002 a rock avalanche occurred immediately to the south-west of Laguna Safuna Alta, in the Cordillera Blanca. The geomorphic evidence for the nature, magnitude and consequences of this event was investigated in August 2002. Field mapping indicated that the avalanche deposited 8,20 × 106 m3 of rock into the lake and onto the surface of the frontal region of Glaciar Pucajirca, which flows into the lake. Repeated bathymetric surveying indicated that ,5 × 106 m3 of this material was deposited directly into the lake. The immediate effect of this event was to create a displacement wave that gained in height as it travelled along the lake basin, overtopping the impounding moraine at the lake's northern end. To achieve overtopping, the maximum wave height must have been greater than 100 m. This, and subsequent seiche waves, caused extensive erosion of both the proximal and distal faces of the impounding terminal moraine. Further deep gullying of the distal face of this moraine resulted from the supply of pressurized water to the face via a relief overflow tunnel constructed in 1978. Two-dimensional, steady-state analysis of the stability of the post-avalanche moraine rampart indicates that its proximal face remains susceptible to major large-scale rotational failure. Copyright © 2005 John Wiley & Sons, Ltd. [source] Two-dimensional, Non-Doppler Strain Imaging during Anesthesia and Cardiac SurgeryECHOCARDIOGRAPHY, Issue 3 2009F.A.S.E., Nikolaos J. Skubas M.D. Transesophageal echochardiography (TEE) has become an essential intraoperative monitor during general anesthesia for cardiac surgical procedures. In clinical practice, ventricular function is visually evaluated using gray scale and Doppler modes, despite the fact that subjective interpretation is influenced by level of experience and training. Echocardiographic strain imaging measures cardiac deformation and provides objective quantification of regional myocardial function. Non-Doppler strain, which is derived by tracking speckles from two-dimensional (2D) images, bypasses the limitations of Doppler-based strain measurements and evaluates the complex myocardial deformation along three dimensions. As a result, longitudinal shortening, circumferential thinning and radial thickening can be quantified using standard midesophageal and transgastric views, being acquired during a comprehensive TEE examination. Once non-Doppler strain becomes available on "real time," it will have the potential to become a valuable tool for detection of ischemia on the regional level and objective quantification of global ventricular function. [source] Detection of tmRNA-mediated trans-translation products in Bacillus subtilisGENES TO CELLS, Issue 3 2002Ai Fujihara Background: Bacterial tmRNA (10Sa RNA) is involved in a trans -translation reaction, which contributes to the degradation of incompletely synthesized peptides and the recycling of stalled ribosomes. To investigate the physiological roles of this reaction in Bacillus subtilis, we devised a system for detecting the proteins that are subject to in vivo trans -translation. Results: The wild-type tmRNA gene (ssrA) in the genome was replaced by a variant ssrA encoding a tag-peptide sequence containing six histidine residues (His-tag) and two aspartic acids at the C-terminus. The His-tagged proteins that accumulated in the cells without degradation were fractionated by Ni2+ -NTA column and gel electrophoresis and were detected by Western blotting with an anti-His-tag antibody. The results showed that the trans -translation occurred more frequently at a high temperature (50 °C) than at a low temperature (37 °C). Two-dimensional (2D) gel electrophoresis of the products revealed many distinct spots, which represent specific target proteins for the trans -translation reaction. Furthermore, the 2D gel patterns of the products from cells cultured at high and low temperatures were apparently different. Several tagged proteins were identified by the N-terminal amino acid sequences of the products. Conclusion:Trans -translation occurs more frequently at high temperature than at low temperature, and different proteins are tagged at different temperatures. [source] Effect of the plate thermal resistance on the heat transfer performance of a corrugated thin plate heat exchangerHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2006Hiroshi Iwai Abstract Two-dimensional conjugate conduction/convection numerical simulations were carried out for flow and thermal fields in a unit model of a counter-flow-type corrugated thin plate heat exchanger core. The effects of the thermal resistance of the solid plate, namely the variation of the plate thickness and the difference of the plate material, on the heat exchanger performance were examined in the Reynolds number range of 100 Floodplain friction parameterization in two-dimensional river flood models using vegetation heights derived from airborne scanning laser altimetryHYDROLOGICAL PROCESSES, Issue 9 2003David C. Mason Abstract Two-dimensional (2-D) hydraulic models are currently at the forefront of research into river flood inundation prediction. Airborne scanning laser altimetry is an important new data source that can provide such models with spatially distributed floodplain topography together with vegetation heights for parameterization of model friction. The paper investigates how vegetation height data can be used to realize the currently unexploited potential of 2-D flood models to specify a friction factor at each node of the finite element model mesh. The only vegetation attribute required in the estimation of floodplain node friction factors is vegetation height. Different sets of flow resistance equations are used to model channel sediment, short vegetation, and tall and intermediate vegetation. The scheme was tested in a modelling study of a flood event that occurred on the River Severn, UK, in October 1998. A synthetic aperture radar image acquired during the flood provided an observed flood extent against which to validate the predicted extent. The modelled flood extent using variable friction was found to agree with the observed extent almost everywhere within the model domain. The variable-friction model has the considerable advantage that it makes unnecessary the unphysical fitting of floodplain and channel friction factors required in the traditional approach to model calibration. Copyright © 2003 John Wiley & Sons, Ltd. [source] Resolution of neutron three-axis spectrometers using acceptance diagramsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2002L. D. Cussen Two-dimensional `acceptance diagrams' are used to discuss the transmission function and the resolution of neutron three-axis spectrometers. The discussion is simplified by assuming rectangular rather than the usual Gaussian transmission profiles for the beam elements, i.e. collimators and crystal mosaic spreads, but the results can be applied to the Gaussian profile approximation. The formalism clearly shows the effects of beam elements on the instrument transmission to the detector. Suitable choices of beam elements are determined to match the transmission functions of the primary and secondary spectrometers and hence optimize measurements. The effect of sample mosaic is addressed. The `focusing angle' for inelastic scattering is determined and discussed. [source] Two-dimensional and three-dimensional sonography of conjoined twinsJOURNAL OF CLINICAL ULTRASOUND, Issue 2 2002Fernando Bonilla-Musoles MD Abstract Purpose The aim of this study was to evaluate and compare the diagnostic capabilities of 2-dimensional (2D) and 3-dimensional (3D) sonography for the study of conjoined twins. Methods Four pregnant women with an initial 2D sonographic diagnosis of conjoined twins were examined with color Doppler sonography, 3D multiplanar sonography, and orthogonal plane imaging and 3D surface rendering. Results All 4 cases of conjoined twins were initially diagnosed with either transvaginal or transabdominal 2D sonography. 3D sonography afforded more realistic views and demonstrated more clearly the linking areas and surface anomalies, but 2D and color Doppler sonography provided more definitive and specific information about shared organs. Conclusions Although 2D sonography is the primary modality for diagnosing and evaluating conjoined twins, color Doppler and 3D sonography can sometimes provide additional information that assists in the clinical management of these twins. 3D sonography also provides images that are easier for parents to understand, which can help them with decision making. © 2002 John Wiley & Sons, Inc. J Clin Ultrasound 30:68,75, 2002; DOI 10.1002/jcu.10035 [source] Aortic Stenosis: Assessment of the Patient at RiskJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 6 2007KHUNG KEONG YEO M.B.B.S. The true incidence of aortic stenosis among the general population is unknown but aortic sclerosis, its precursor, has been estimated to affect about 25% of people over age 65, while an estimated 3% of the population over age 75 have severe aortic stenosis. Severe aortic stenosis, when accompanied by symptoms of angina, syncope, or heart failure, is associated with high mortality rates. Two-dimensional and Doppler echocardiography are cornerstone tools for the evaluation and monitoring of aortic stenosis. Echocardiography helps identify the patient at risk of death and guide timing of aortic valve replacement. Other important diagnostic tools include cardiac catheterization, treadmill stress testing, and dobutamine stress echocardiography, although their use is limited to specific patient populations. Aortic valve replacement carries a significant operative risk of approximately 4.0%. However, risk of operative mortality varies according to comorbidities and disease presentation. There are many risk models that guide estimation of the risk of operative mortality. Understanding operative risk is important in patient care and the selection of patients for aortic valve replacement. [source] Two- and three-dimensional multinuclear stray-field imaging of rotating samples with magic-angle spinning (STRAFI-MAS): From bio to inorganic materialsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010Alan Wong PhD Abstract Purpose: To revisit and illustrate the potential of a simple and effective multidimensional stray-field imaging technique with magic-angle spinning, known as STRAFI-MAS. Materials and Methods: STRAFI-MAS images are acquired with a standard NMR magnet and a traditional magic-angle sample spinning (MAS) probe. The stray-field gradients are achieved by placing the MAS probe, along the z -direction, at a distance from the center of the magnet. No pulsed-field gradients are applied. The multidimensional spatial encoding is carried out by synchronizing the radiofrequency pulses with the sample MAS rotation. Results: Two-dimensional (2D) and 3D multinuclear images of various phantoms, including a tibia bone and silicon carbide, are recorded. Images of inorganic solids containing quadrupolar nuclei, 23Na and 27Al, are also explored for the first time by STRAFI-MAS. Conclusion: We have demonstrated that STRAFI-MAS is a simple and user-friendly technique for multidimensional imaging without the need of imaging equipment. With the current advancements in NMR and MRI methodologies, STRAFI-MAS is expected to be further developed and improved. We anticipate that STRAFI-MAS can spark a wide spectrum of interest, from material to bio science, where can benefit from high-resolution images. J. Magn. Reson. Imaging 2010;32:418,423. © 2010 Wiley-Liss, Inc. [source] Review of left-to-right shunting patent ductus arteriosus and short term outcome in 98 dogsJOURNAL OF SMALL ANIMAL PRACTICE, Issue 9 2002N. Van Israël The case records of 98 dogs with a left-to-right shunting patent ductus arteriosus (PDA) were reviewed. There were 35 breeds represented, with a female to male ratio of 3:1. Forty per cent of the dogs were older than one year at initial presentation and 31 per cent had clinical signs attributable to PDA. A left heart base continuous murmur of grade IV/VI or higher was noted in 90 per cent of the dogs. On electrocardiography, the most common abnormalities were tall R waves (63 per cent) and deep QII waves (62 per cent). The radiographic triad of dilation of the descending aorta with enlargement of the main pulmonary artery segment and left atrium, typical of PDA, was noted in only 26 per cent of cases. Two-dimensional (2D) and M-mode echocardiography detected left atrial enlargement (35 per cent) and an increased left ventricular diameter in diastole (82 per cent) and systole (84 per cent) as the most common abnormalities. Doppler echocardiography demonstrated increased aortic outflow velocities in 66 per cent of cases. The overall short-term successful outcome in this study was 95 per cent. There was no significant difference between surgical ductal ligation using a standard technique or the Jackson-Henderson technique in terms of survival, occurrence of haemorrhage or residual shunting. The number of interventional procedures used in this study was too low for statistical comparison, but there appeared to be a trend towards a higher rate of residual shunting and a lower fatality rate using a coil occlusion technique. [source] Increased ,-Myosin Heavy Chain in Acute Cellular Rejection Following Human Heart TransplantationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 4 2002Mohamad H. Yamani Background: Increased expression of smooth muscle and nonmuscle myosin heavy chains has been previously reported in animal models of cardiac allograft rejection. However, altered expression of ,-myosin heavy chain in human cardiac rejection has not been determined. Methods: Two-dimensional (2D)-gel electrophoresis of endomyocardial biopsies taken from patients with (Grade 3A, n = 6) and without (Grade 0, n = 6) acute rejection were analyzed. Increased expression of two protein spots (MW , 12 kDa) were identified in the presence of acute rejection and were further characterized by mass spectrometry analysis. In patients who had acute rejection, protein expression was subsequently analyzed by immunoblotting on biopsies preceding, during, and following treatment of rejection. Results: Mass spectrometric analysis of the protein spots detected 6 and 22 tryptic peptides, respectively. Protein sequence database search analysis identified the first protein as ,-myosin heavy chain and the second spot consisted of proteins of unidentified nature that may represent novel proteins. Immunoblotting analysis showed 1.4 × fold increase (p <,0.01) of protein expression of ,-myosin heavy chain expression in the presence of acute rejection. Conclusions: To our knowledge, this is the first 2D-gel study to describe increased expression of ,-myosin heavy chain and other proteins of unidentified nature in association with human cardiac allograft rejection. [source] Linkage of Sevier thrusting episodes and Late Cretaceous foreland basin megasequences across southern Wyoming (USA)BASIN RESEARCH, Issue 4 2005Shao-Feng Liu ABSTRACT Deposition and subsidence analysis, coupled with previous structural studies of the Sevier thrust belt, provide a means of reconstructing the detailed kinematic history of depositional response to episodic thrusting in the Cordilleran foreland basin of southern Wyoming, western interior USA. The Upper Cretaceous basin fill is divided into five megasequences bounded by unconformities. The Sevier thrust belt in northern Utah and southwestern Wyoming deformed in an eastward progression of episodic thrusting. Three major episodes of displacement on the Willard-Meade, Crawford and ,early' Absaroka thrusts occurred from Aptian to early Campanian, and the thrust wedge gradually became supercritically tapered. The Frontier Formation conglomerate, Echo Canyon and Weber Canyon Conglomerates and Little Muddy Creek Conglomerate were deposited in response to these major thrusting events. Corresponding to these proximal conglomerates within the thrust belt, Megasequences 1, 2 and 3 were developed in the distal foreland of southern Wyoming. Two-dimensional (2-D) subsidence analyses show that the basin was divided into foredeep, forebulge and backbulge depozones. Foredeep subsidence in Megasequences 1, 2 and 3, resulting from Willard-Meade, Crawford and ,early' Absaroka thrust loading, were confined to a narrow zone in the western part of the basin. Subsidence in the broad region east of the forebulge was dominantly controlled by sediment loading and inferred dynamic subsidence. Individual subsidence curves are characterized by three stages from rapid to slow. Controlled by relationships between accommodation and sediment supply, the basin was filled with retrogradational shales during periods of rapid subsidence, followed by progradational coarse clastic wedges during periods of slow subsidence. During middle Campanian time (ca. 78.5,73.4 Ma), the thrust wedge was stalled because of wedge-top erosion and became subcritical, and the foredeep zone eroded and rebounded because of isostasy. The eroded sediments were transported far from the thrust belt, and constitute Megasequence 4 that was mostly composed of fluvial and coastal plain depositional systems. Subsidence rates were very slow, because of post-thrusting rebound, and the resulting 2-D subsidence was lenticular in an east,west direction. During late Campanian to early Maastrichtian time, widespread deposits of coarse sediment (the Hams Fork Conglomerate) aggraded the top of the thrust wedge after it stalled, prior to initiation of ,late' Absaroka thrusting. Meanwhile Megasequence 5 was deposited in the Wyoming foreland under the influence of both the intraforeland Wind River basement uplift and the Sevier thrust belt. [source] Maternal cardiac function and uterine artery Doppler at 11,14 weeks in the prediction of pre-eclampsia in nulliparous womenBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 3 2008A Khaw Objective, To assess maternal cardiac function in nulliparous women in the first trimester of pregnancy and evaluate its potential role for predicting pre-eclampsia and small for gestational age (SGA). Design, Prospective, observational, cross-sectional study. Setting, Maternity unit of a teaching hospital. Population, Nulliparous women with singleton pregnancies presenting consecutively for routine antenatal care (n= 534). Methods, Two-dimensional and M-mode echocardiography and uterine artery Dopplers were carried out at 11-14 weeks. Main outcome measures, Cardiac output (CO), stroke volume (SV), mean arterial pressure (MAP), total vascular resistance and uterine artery pulsatility index (UAPI) were compared in four outcome groups according to the development of pre-eclampsia and/or SGA. Results, Compared with the normal outcome group (n= 457), in those with pre-eclampsia but not SGA (n = 8), CO and MAP were increased; in the group with pre-eclampsia and SGA (n= 19) MAP, TRP and UAPI were increased and in the group with SGA but no pre-eclampsia (n= 50) total peripheral resistance and UAPI were increased. Independent predictors of pre-eclampsia were MAP, SV and UAPI and of SGA SV and UAPI. Conclusions, Alterations in maternal cardiac function and UAPI are observed in the first trimester of pregnancy in nulliparous women that subsequently develop pre-eclampsia and/or SGA. [source] Three-Dimensional Surface Texture Characterization of Portland Cement Concrete PavementsCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 3 2007Ala Abbas Ten PCC field cores of varying surface textures were included in the analysis. X-ray Computed Tomography (CT) was used to scan the upper portion of these cores, resulting in a stack of two-dimensional grayscale images. Image processing techniques were utilized to isolate the void pixels from the solid pixels and reconstruct the three-dimensional surface topography. The resulting three-dimensional surfaces were reduced to two-dimensional "map of heights" images, whereby the grayscale intensity of each pixel within the image represented the vertical location of the surface at that point with respect to the lowest point on the surface. The "map of heights" images were analyzed using four mathematical methods, namely the Hessian model, the Fast Fourier transform (FFT), the wavelet analysis, and the power spectral density (PSD). Results obtained using these methods were compared to the mean profile depth (MPD) computed in accordance with ASTM E1845. [source] Simulation of Direct-Current Microdischarges for Application in Electro-Thermal Class of Small Satellite Propulsion DevicesCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-2 2007P. S. Kothnur Abstract Microdischarges are miniature non-equilibrium plasma discharges with characteristic dimensions of ,10's,100's ,m and relatively high operating pressures of ,10's,100's Torr. Microdischarges possess several unique properties that have been exploited in a number of new applications. We have recently proposed amicrodischargebased electro-thermal class of microthrusters for small satellite propulsion. These devices utilize intense gas heating in microdischarges to preheat a propellant gas stream before it is expanded in a micronozzle to produce thrust; thereby improving specific impulse of the device over a conventional cold gas microthruster. This paper addresses direct-current microdischarge phenomena in a flowing gas stream. A two-dimensional, selfconsistent, fluid model of a helium microdischarge in a bulk gas flow is developed. For relatively high current/power levels considered in this study, the microdischarge operates in an abnormal glow mode with positive differential resistivity. Increasing discharge pressures for fixed power and bulk flow rates results in a decrease in charged species densities and the electron and gas temperatures. Also the discharge becomes increasingly constricted with increasing pressures, resulting in a more normal glow mode-like operation. Increasing bulk flow rates results in exactly the same trends as increasing pressures. For given input power and pressure, there exists an optimum flow rate for which the average outlet gas temperature from the discharge is a maximum. An increase in input electrical power results in an almost linear increase in the gas temperatures; this property of microdischarges is the key feature that is exploited in our microdischarge-based thruster concept. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The calcium-conducting ion channel transient receptor potential canonical 6 is involved in macrophage inflammatory protein-2-induced migration of mouse neutrophils,ACTA PHYSIOLOGICA, Issue 1 2009N. Damann Abstract Aim:, The role of the calcium-conducting ion channel transient receptor potential canonical 6 (TRPC6) in macrophage inflammatory protein-2 (MIP-2) induced migration of mouse neutrophils was investigated. Methods:, Neutrophil granulocytes isolated from murine bone marrow of wild-type (TRPC6+/+) and TRPC6 knockout (TRPC6,/,) mice were tested for the presence of TRPC6 channel expression using quantitative real-time polymerase chain reactions and immunocytochemistry. The effect of different stimuli (e.g. MIP-2, 1-oleoyl-2-acetyl-sn-glycerol, formyl-methionyl-leucyl-phenylalanin) on migration of isolated neutrophils was tested by two-dimensional (2D) migration assays, phalloidin staining and intracellular calcium imaging. Results:, We found that neutrophil granulocytes express TRPC6 channels. MIP-2 induced fast cell migration of isolated neutrophils in a 2D cell-tracking system. Strikingly, MIP-2 was less potent in neutrophils derived from TRPC6,/, mice. These cells showed less phalloidin-coupled fluorescence and the pattern of cytosolic calcium transients was altered. Conclusions:, We describe in this paper for the first time a role for transient receptor potential (TRP) channels in migration of native lymphocytes as a new paradigm for the universal functional role of TRPs. Our data give strong evidence that TRPC6 operates downstream to CXC-type Gq -protein-coupled chemokine receptors upon stimulation with MIP-2 and is crucial for the arrangement of filamentous actin in migrating neutrophils. This is a novel cell function of TRP channel beyond their well-recognized role as universal cell sensors. [source] Projecting 2D gene expression data into 3D and 4D spaceDEVELOPMENTAL DYNAMICS, Issue 4 2007Victor E. Gerth Abstract Video games typically generate virtual 3D objects by texture mapping an image onto a 3D polygonal frame. The feeling of movement is then achieved by mathematically simulating camera movement relative to the polygonal frame. We have built customized scripts that adapt video game authoring software to texture mapping images of gene expression data onto b-spline based embryo models. This approach, known as UV mapping, associates two-dimensional (U and V) coordinates within images to the three dimensions (X, Y, and Z) of a b-spline model. B-spline model frameworks were built either from confocal data or de novo extracted from 2D images, once again using video game authoring approaches. This system was then used to build 3D models of 182 genes expressed in developing Xenopus embryos and to implement these in a web-accessible database. Models can be viewed via simple Internet browsers and utilize openGL hardware acceleration via a Shockwave plugin. Not only does this database display static data in a dynamic and scalable manner, the UV mapping system also serves as a method to align different images to a common framework, an approach that may make high-throughput automated comparisons of gene expression patterns possible. Finally, video game systems also have elegant methods for handling movement, allowing biomechanical algorithms to drive the animation of models. With further development, these biomechanical techniques offer practical methods for generating virtual embryos that recapitulate morphogenesis. Developmental Dynamics 236:1036,1043, 2007. © 2007 Wiley-Liss, Inc. [source] The effects of age and sex on mental rotation performance, verbal performance, and brain electrical activityDEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2002Jonathan E. Roberts Abstract This study examined the effects of age and sex on mental rotation performance, verbal performance, and brain-wave activity. Thirty-two 8-year-olds (16 boys) and 32 college students (16 men) had EEG recorded at baseline and while performing four computerized tasks: a two-dimensional (2D) gingerbread man mental rotation, a 2D alphanumeric mental rotation, of three-dimensional (3D) basketball player mental rotation, and lexical decision making. Additionally, participants completed a paper- and pencil water level task and an oral verbal fluency task. On the 2D alphanumeric and 3D basketball player mental rotation tasks, men performed better than boys, but the performance of women and girls did not differ. On the water level task, men performed better than women whereas there was no difference between boys and girls. No sex differences were found on the 2D gingerbread man mental rotation, lexical decision-making, and verbal fluency tasks. EEG analyses indicated that men exhibited left posterior temporal activation during the 2D alphanumeric task and that men and boys both exhibited greater left parietal activation than women and girls during the 2D gingerbread man task. On the 3D basketball player mental rotation task, all participants exhibited greater activation of the right parietal area than the left parietal area. These data give insight into the brain activity and cognitive development changes that occur between childhood and adulthood. © 2002 Wiley Periodicals, Inc. Dev Psychobiol 40: 391,407, 2002. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/dev.10039 [source] Left ventricular diastolic dysfunction in patients with chronic renal failure: impact of diabetes mellitusDIABETIC MEDICINE, Issue 6 2005J. Miyazato Abstract Aims Left ventricular (LV) hypertrophy and LV diastolic dysfunction are cardiac changes commonly observed in patients with chronic renal failure (CRF) as well as hypertension. Although the impairment of LV diastolic function in patients with diabetes mellitus has been shown, little is known about the specific effect of diabetes on LV diastolic function in patients with CRF. The present study was designed to investigate the impact of diabetic nephropathy on LV diastolic dysfunction, independent of LV hypertrophy, in CRF patients. Methods In 67 patients with non-dialysis CRF as a result of chronic glomerulonephritis (n = 33) or diabetic nephropathy (n = 34), and 134 hypertensive patients with normal renal function, two-dimensional and Doppler echocardiographic examinations were performed, and LV dimension, mass, systolic function, and diastolic function were evaluated. Results LV mass was increased and LV diastolic dysfunction was advanced in subjects with CRF compared with hypertensive controls. In the comparison of echocardiographic parameters between the two groups of CRF patients, i.e. chronic glomerulonephritis and diabetic nephropathy groups, all indices of LV diastolic function were more deteriorated in the diabetic nephropathy group than in the chronic glomerulonephritis group, although LV structure including hypertrophy and systolic function did not differ between the groups. In a multiple regression analysis, the presence of diabetes (i.e. diabetic nephropathy group) was a significant predictor of LV diastolic dysfunction in CRF subjects, independent of other influencing factors such as age, blood pressure, renal function, anaemia and LV hypertrophy. Conclusion The present findings suggest that LV diastolic dysfunction, independent of LV hypertrophy, is specifically and markedly progressed in patients with CRF as a result of diabetic nephropathy. [source] Depicting of a Cleft Mitral Valve by Real Time Three-Dimensional Transesophageal EchocardiographyECHOCARDIOGRAPHY, Issue 3 2010F.E.S.C., Mehmet Özkan M.D. We report the usefulness of real time three-dimensional transesophageal echocardiography in comprehensive delineation of cleft mitral valve. This new technique may be a useful supplement to two-dimensional and three-dimensional transthoracic echocardiography in the assessment of this pathology. (Echocardiography 2010;27:356-358) [source] Segmental Contribution to Left Ventricular Systolic Function at Rest and Stress: A Quantitative Real Time Three-Dimensional Echocardiographic StudyECHOCARDIOGRAPHY, Issue 2 2010F.A.S.E., Smadar Kort M.D. Objective: To assess the relative contribution of each myocardial segment to global systolic function during stress using real time three-dimensional echocardiography (RT3DE). Background: During stress, global augmentation in contractility results in an increased stroke volume. The relative contribution of each myocardial segment to these volumetric changes is unknown. Methods: Full volume was acquired using RT3DE at rest and following peak exercise in 22 patients who had no ischemia and no systolic dyssynchrony on two-dimensional (2D) stress echocardiography. The following were calculated at rest and peak stress: end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), relative SV, and relative EF. Results: With stress, an increase in global EDV from 90.8 to 101.1 ml (P < 0.001), SV from 59 to 78.4 ml (P = 0.01), and EF from 65.6 to 78.4% (P = 0.001) was observed. ESV decreased from 31.8 to 22.7 ml (P < 0.001). Segmental analysis revealed significantly higher SV, relative SV, and relative EF for the basal anterior, basal anterolateral, and basal inferolateral segments compared with the apical septum and apical inferior segments at both rest and stress (P < 0.001). The SV, relative SV, and relative EF increased significantly from apex to mid to base at both rest and stress (P < 0.001). Conclusions: The relative volumetric contribution of each myocardial segment to global left ventricular systolic function at rest and stress is not uniform. The basal segments contribute more than the mid and apical segments. Specifically, the basal anterior, basal anterolateral, and basal inferolateral segments contribute the most to augmentation of left ventricular systolic function with exercise. (ECHOCARDIOGRAPHY 2010;27:167-173) [source] Tricuspid Regurgitation after Orthotopic Heart TransplantationECHOCARDIOGRAPHY, Issue 1 2010Nishant Kalra M.D. Background: Tricuspid regurgitation (TR) is a relatively common abnormality in normal adults as well as after orthotopic heart transplantation (OHT). A few studies have shown reduction in the incidence of TR after OHT by total bicaval surgical anastomosis technique. Other studies reported no significant difference in the rates of TR between the standard and bicaval techniques. Objective: Evaluate and compare the degree of TR after OHT by standard and bicaval anastomosis techniques. Method: Echocardiograms from the first 56 consecutive patients that had the total bicaval surgical technique performed were retrospectively reviewed and compared with the last 57 consecutive patients who had the standard biatrial technique performed. Patients with adequate two-dimensional and Doppler echocardiograms were included. Results: No statistical difference was observed for each grade of TR at both early and late time points. No significant difference was observed between the TR velocities of both biatrial and bicaval anastomosis patients at different periods. Conclusion: There appears to be no difference between the TR severity and TR velocity at early and late time points regardless of anastomotic technique. (Echocardiography 2010;27:1-4) [source] Observer Variation in the Echocardiographic Measurement of Maximum Atrial Septal Excursion: A Comparison of M-Mode with Two-Dimensional or Transesophageal EchocardiographyECHOCARDIOGRAPHY, Issue 10 2009Background: Atrial septal aneurysm is typically diagnosed by transthoracic two-dimensional or transesophageal echocardiography (2DE or TEE). Such techniques are highly dependent on visual inspection which predisposes to observer variation. This study compares inter- and intraobserver variations in the measurement of maximum atrial septal excursion (MASE) obtained using transthoracic M-mode echocardiography (MME) with that obtained using 2DE or TEE. Methods: Consecutive patients with highly mobile atrial septal motion by visual inspection during 2DE or TEE were studied. MASE was estimated visually on 2DE or TEE. MME tracings were obtained with the cursor bisecting the parabola formed by the atrial septum at its maximum deviation from the midline. Electronic calipers were used to measure MASE for all echocardiographic techniques. Two observers provided two measurements each. Observer variation was determined by assessing standard deviation and confidence intervals of inter- and intraobserver differences. Results: Interobserver analysis showed standard deviations of 0.077 cm (95% CI 0.065,0.094) for MME and 0.280 cm (95% CI 0.242,0.334) for 2DE or TEE. Intraobserver analysis showed standard deviations of 0.08 cm (95% CI 0.068,0.101) for MME and 0.318 cm (95% CI 0.274,0.381) for 2DE or TEE. The mean magnitude of measured MASE was 0.44 cm higher with MME than with 2DE or TEE (95% CI 0.068,0.101). Conclusions: MME assessment of MASE is associated with substantially lower inter- and intraobserver variation than 2DE or TEE assessment. The magnitude of MASE is substantially higher with MME than with 2DE or TEE. [source] Usefulness of Live/Real Time Three-Dimensional Transthoracic Echocardiography in Evaluation of Prosthetic Valve FunctionECHOCARDIOGRAPHY, Issue 10 2009Preeti Singh M.D. We studied 31 patients with prosthetic valves (PVs) using two-dimensional and three-dimensional transthorathic echocardiography (2DTTE and 3DTTE, respectively) in order to determine whether 3DTTE provides an incremental value on top of 2DTTE in the evaluation of these patients. With 3DTTE both leaflets of the St. Jude mechanical PV can be visualized simultaneously, thereby increasing the diagnostic confidence in excluding valvular abnormalities and overcoming the well-known limitations of 2DTTE in the examination of PVs, which heavily relies on Doppler. Three-dimensional transthorathic echocardiography provides a more comprehensive evaluation of PV regurgitation than 2DTTE with its ability to more precisely quantify PV regurgitation, in determining the mechanism causing regurgitation, and in localizing the regurgitant defect. Furthermore, 3DTTE is superior in identifying, quantifying, and localizing PV thrombi and vegetations, in addition to the unique feature of providing a look inside mass lesions by serial sectioning. These preliminary results suggest the superiority of 3DTTE over 2DTTE in the evaluation of PVs and that it provides incremental knowledge to the echocardiographer. [source] Live/Real Time Three-Dimensional Transthoracic Echocardiographic Assessment of Pericardial DiseaseECHOCARDIOGRAPHY, Issue 10 2009Carlos Martinez Hernandez M.D. We studied 19 patients with pericardial disease using two-dimensional and three-dimensional transthorathic echocardiography (2DTTE and 3DTTE, respectively) in order to determine whether 3DTTE provides incremental value on top of 2DTTE in the evaluation of these patients. With 3DTTE a more comprehensive assessment of pericardial effusion can be made and both the parietal and visceral layers of the pericardium can be visualized en face and examined for pathologies and fibrin deposits. In our series of patients, 3DTTE was superior to 2DTTE in uncovering mass lesions involving the pericardium such as tuberculous granulomas and metastatic disease. Furthermore, it provided a better assessment of the nature of pericardial lesions, such as pericardial and mediastinal hematomas, pericardial cysts, and metastatic disease to the pericardium by sequential cropping of the 3D data sets and visualizing the interior of the lesions in a manner not possible with 2DTTE. It was also valuable in determining the extent of pericardial calcification in pericardial constriction and in measuring the size of pericardial masses. These preliminary results suggest the superiority of 3DTTE over 2DTTE in the evaluation of pericardial diseases and that it provides incremental knowledge to the echocardiographer. [source]
| | |||||||||||||||||||||||||||||||||||||||||||||