Radial Plane Research Articles

Abstract 18798: Gata4 and Gata6 Are Necessary for Neonatal but Not Adult Cardiac Function Under Normal Physiological Conditions

Objective: Fetal inactivation of the cardiac transcription factors Gata4 and Gata6 has been shown to cause postnatal heart dysfunction. However, the postnatal requirement for these transcription factors has not been defined. Methods: Using systemic delivery of recombinant adeno-associated virus 9 expressing Cre from the cardiac specific TNNT2 promoter (1.2E x 12VG/gram body weight; n=6), we inactivated floxed Gata4 and Gata6 alleles in neonatal or adult hearts. Left ventricular performance was followed serially using M-mode echocardiography and two-dimensional speckle tracking-derived myocardial tissue deformation (Visualsonics Vevo 2100) under light isofluorane anesthesia. The intervention group was compared to a control AAV-TNNT2 encoding luciferase. Findings: In the neonatal heart (P1-P5), effective knock-down of Gata4 and Gata6 (n=6 mice) was confirmed by Western blot and quantitative reverse-transcription PCR of myocardial tissue: We observed a 4.9-fold reduction in Gata4 expression; (95% C.I. +/-1.2) and a 6-fold reduction in Gata6 expression (95% C.I. +/- 1.2). Over the course of 5 days, left ventricular ejection fraction decreased significantly from a mean of 81% to 39% +/- 3% SEM (p<0.0001). Strain analysis confirmed a global reduction in myocardial performance after knock-down. The expression of heart failure markers, m-ANF and MYH7, were markedly up-regulated at 17-fold and 24-fold, respectively. In the adult heart (postnatal weeks 6-9, n=6), despite a technically successful systemic delivery of rAAV9, no noted left ventricular dysfunction was apparent on subsequent serial follow-up by m-mode echocardiography. Similarly, myocardial performance, as measured by strain & strain rate analysis in the longitudinal, circumferential and radial planes, remained equal in the intervention group to that of the control group. Conclusions: AAV9-TNNT2-Cre is an effective means of achieving temporally controlled inactivation of floxed alleles in the postnatal heart. Gata4 and Gata6 are required to maintain normal left ventricular systolic function during neonatal life, but are no longer required in adulthood under normal physiological conditions.

Running Behavior of a High-Speed Spindle Using a Micro-Mist Lubrication System

This work investigates the effect of lubrication parameter on the operation performance of a high-speed spindle using a micro-mist lubrication system. Experiments are conducted through a long-time spindle test under different combinations of oil-supply parameter and rotating speed for a micro-mist lubricated spindle. The correspondent relationships among temperature rise, vibration, oil-supply parameter and rotating speed are established through the experiments under moderate oil-supply. The results show that the better oil-supply parameter combinations exist under different spindle rotating speeds, which could ensure the sufficient and adequate lubricating oil film to be formed and a stable elasto-hydro-dynamic lubrication could be further created during the operation period. The minimization of the temperature rise in bearings may be attained. Increasing air pressure contributed to the reduction in bearing temperature, but saturation might be appeared after the pressure level reached to a certain extent. The dynamic response measurement shows that this prototype spindle has an overly large vibration and rotation unbalance on the radial plane, which highlights the unstable operation problem of the spindle. Therefore, it is necessary to improve the constructed procedures, such as design, manufacture, and assembly for further use, to enhance the operation performance of the spindle. The analysis, measurement and diagnosis procedures established in this study could be helpful to uplift the related techniques for precision machinery industry.

Shared Morphology of Slipped Capital Femoral Epiphysis and Femoroacetabular Impingement in Early-onset Arthritis

A subclinical form of slipped capital femoral epiphysis (SCFE) can lead to subtle morphologic abnormalities, such as cam-type femoroacetabular impingement (FAI). Femoroacetabular impingement is a mechanical hip abnormality that typically affects young populations and leads to hip pain and premature osteoarthritis. Imaging is critical to diagnosis, whether by radiograph, magnetic resonance imaging, or computed tomography. The authors investigated the use of imaging to detect characteristics of subclinical SCFE and cam-type FAI in patients undergoing hip resurfacing. They retrospectively assessed computed tomography scans of 81 hips from 75 patients. Measurements were taken of the proximal femur and included the alpha angle, head-neck tilt, and anterior offset taken in both the conventional oblique axial plane and the radial plane. The cohort consisted of 68 men and 13 women with an average age of 52 years. Ninety percent of hips on the oblique axial view and 95% of hips on the radial view were found to have pathologically increased alpha angles. Negative correlations were found between the alpha angle and head-neck tilt and positive correlations between head-neck tilt and anterior offset ratio. Sixty percent and 68% of hips in the oblique axial and radial planes, respectively, were abnormal for the alpha angle, head-neck tilt, and anterior offset ratio, strongly suggesting SCFE morphology. This study's results show similarity in morphology between cam-type FAI and SCFE, known precursors to osteoarthritis, in an early arthritic patient population.

4.6: Anisotropy in solid breast lesions at shear wave elastography: relationship to the radial plane and implications for benign/malignant differentiation

Anisotropy is the directional dependence of the measurement of a property. As breast tissue structure and some breast diseases (DCIS) are anisotropic in structure, we aimed to establish the frequency, degree and diagnostic value of shear wave elastography anisotropy in solid breast lesions.

Numerical analysis of the fin spacing effect on the horseshoe vortex system evolution in a two-rows finned-tube heat exchanger

Purpose – In finned-tube heat exchangers, the array of tubes generates three-dimensional vortices at fin-tube junctions. Theses vortices known as horseshoe vortex (HSV) system are responsible of flow mixing and heat transfer increase. The purpose of this paper is to focus on the effect of the fin spacing on the formation, the spatial evolution and dissipation of the HSV system at fin-tube junctions in a two-rows finned-tube heat exchanger. The global characterisation of the heat exchanger performance is also presented. Design/methodology/approach – The flow structure is numerically analysed through the use of computational fluid dynamics tools. The different vortices of the HSV system are highlighted and quantitatively analysed at each fin-tube junction with vorticity, wall shear stress analysis and two-dimensional streamline plots around tubes. Findings – The results show that the primary and secondary vortices of the HSV system have antagonistic behaviors with respect to the azimuthal angle variation. The optimum fin spacing ratio E/D that generates the most intense first primary vortex in the HSV system lies between 0.20 and 0.25. Similar observation are made on the thermalhydraulic performance of the heat exchanger as j/f exhibits a maximum value for a fin spacing ratio E/D=0.25. Research limitations/implications – A detailed URANS simulation shows that even if the flow remains steady in the core of the heat exchanger, unsteady behavior is noticed in the wake of the second tube. Originality/value – In this study, the flow topology is quantitatively analysed in successive radial planes around heat exchanger tubes. The strong effect of the fin spacing on the HSV generation and dissipation is deeply analysed.

High-speed imaging of transient diesel spray behavior during high pressure injection of a multi-hole fuel injector

Reliable prediction of spray penetration and spray break-up is required to achieve increases in fuel efficiency and reduction of emissions in diesel engines. Of particular interest is the early transient-flow regime. In the current work, diesel fuel spray development was studied using high-speed imaging of a high-pressure diesel common-rail fuel injector mounted in a spherical constant volume combustion chamber. The fuel injector nozzle had four holes aligned on a radial plane with diameters of 90, 110, 130, and 150μm. Fuel was injected into a room temperature T=298K (±1.5%), nitrogen environment at chamber densities of 17.5, 24.2, and 32.7kg/m3 (±3%) and for fuel-rail pressures of 1000, 1500, and 2000bar (±1.5%). High-speed images of the backlit fuel injection were captured at 100,000 frames per second. Image processing algorithms were used to determine fuel spray penetration distance and maximum penetration rate as a function of time. The early time history of the spray penetration was not sensitive to orifice size, orifice location or chamber density at the conditions studied. However, fuel injection pressure significantly affected the spray-tip penetration and time to spray break-up. The experimental results for maximum penetration rate and transition time were compared with various quasi-one-dimensional fuel-spray models. The experimental data indicated a power law relationship for the spray-tip penetration at early times in the spray development, which is consistent with recent recommendations. However, the experimental results for time to spray break up departed from the model predictions at most of the conditions studied, with the model significantly under-predicting the time for spray transition. Furthermore, the spray penetration data showed significant fluctuations in the spray geometry at early times. A fuel spray-tip tracking algorithm was developed and the results showed the maximum penetration distance did not occur along the spray center-line during the transient period of injection and the results quantified the angular location of the maximum penetration distance. These data provide valuable new insights into transient fuel spray behavior and will guide the development of the next generation of spray theory and models.

Experimental Investigation on the Basic Law of Hydraulic Fracturing After Water Pressure Control Blasting

Because of the advantages of integrating water pressure blasting and hydraulic fracturing, the use of hydraulic fracturing after water pressure control blasting is a method that is used to fully transform the structure of a coal-rock mass by increasing the number and range of hydraulic cracks. An experiment to study hydraulic fracturing after water pressure blasting on cement mortar samples (300 × 300 × 300 mm3) was conducted using a large-sized true triaxial hydraulic fracturing experimental system. A traditional hydraulic fracturing experiment was also performed for comparison. The experimental results show that water pressure blasting produces many blasting cracks, and follow-up hydraulic fracturing forces blasting cracks to propagate further and to form numerous multidirectional hydraulic cracks. Four macroscopic main hydraulic cracks in total were noted along the borehole axial and radial directions on the sample surfaces. Axial and radial main failure planes induced by macroscopic main hydraulic cracks split the sample into three big parts. Meanwhile, numerous local hydraulic cracks were formed on the main failure planes, in different directions and of different types. Local hydraulic cracks are mainly of three types: local hydraulic crack bands, local branched hydraulic cracks, and axial layered cracks. Because local hydraulic cracks produce multiple local layered failure planes and lamellar ruptures inside the sample, the integrity of the sample decreases greatly. The formation and propagation process of many multidirectional hydraulic cracks is affected by a combination of water pressure blasting, water pressure of fracturing, and the stress field of the surrounding rock. To a certain degree, the stress field of surrounding rock guides the formation and propagation process of the blasting crack and the follow-up hydraulic crack. Following hydraulic fracturing that has been conducted after water pressure blasting, the integrity of the sample is found to be far lower than after traditional hydraulic fracturing; moreover, both the water injection volume and water injection pressure for hydraulic fracturing after water pressure blasting are much higher than they are for traditional hydraulic fracturing.

SU‐C‐137‐04: Effective Control Limits for Predictive Maintenance (PdM) of Accelerator Beam Uniformity

Purpose: Predictive maintenance programs employ non‐invasive methods to monitor the performance of systems to determine when preemptive intervention is required to maintain high quality performance. The focus of this study is to evaluate the effectiveness of a modified calculation method for the control limits of process control charts (PCC) that will reduce false positive alarms but detect clinically relevant changes in beam uniformity (flatness and symmetry). Methods: Steering coil currents (SCC) for the transverse and radial planes are adjusted such that a reproducibly useful photon or electron beam is available. Performing controlled experiments varying a single SCC, we were able to determine the magnitude of change required to produce a 1% change in beam uniformity. The average and range (Xbar/R) control chart limit calculation was reformulated incorporating a scaling factor (Cm). After monitoring the SCC of 3 accelerators for several months, without detecting any PCC alarms, we intentionally changed the transverse angle and position SCC independently until the beam symmetry differed by ∼1.1% from baseline as confirmed by computerized beam profile scan in water using an ion chamber. These experimental SCC values were plotted in the PCC to determine if they would exceed the modified control limits. Results: The experimental SCC value exceeded the PCC limit for each of the steering coils. Additionally, the capability of the new control limit calculation method was confirmed when an anomaly was detected in the operation of an accelerator in clinical use. Instability in the operation of the 18 MV photon beam was predicted by SPC analysis prior to it being confirmed by service and daily check devices. If the analysis had been performed using the original methodology, a number of false positives would have been reported. Conclusion: Reformulated X‐bar/R chart control limits of SCC can provide an effective predictive maintenance tool for accelerator beam uniformity. This project is supported by a grant from Varian Medical Systems.

WE-E-134-01: Preliminary Application of a Multitaper Generalized Spectrum Approach to Quantify Scatterer Nonrandomness in Breast Lesions

Purpose: The generalized spectrum (GS) has been used to quantify nonrandomness of scattering sources and to characterize breast and liver tissues. In this work, we implement a multitaper GS approach creating parametric images of GS features that describe the degree of nonrandom structure in breast lesions. Methods: This IRB-approved, HIPAA compliant study recruited subjects who were scheduled for core biopsy of a suspicious breast mass. Subjects were scanned with a Siemens Acuson S2000 using a linear array transducer at 15MHz. Radiofrequency (RF) echo data were obtained in radial (parallel to breast lactiferous ducts) and antiradial planes. Cases (n=34) were selected based on the availability of biopsy results and a lesion size of at least 3mm in both planes. The multitaper GS was obtained by computing the correlation matrix of the Fourier transform of RF signal segments tapered by Prolate Spheroidal Sequences. Nonrandomness was quantified by parameterizing the collapsed average of the GS. A region of interest (ROI) within each lesion and each plane was defined,and the mean and standard deviation of the nonrandomness within it were computed. Results: Cases were grouped into: fibroadenoma (n=12, median diameter (MD)=7.6mm),other benign(n=11, MD=8.2mm), invasive ductal carcinoma (IDC) (n=5, MD=6.3mm), and other malignant(n=6, MD=6.9mm). The IDC nonrandomness inter-case median of the mean and standard deviation was 64% and 59% of the values from other lesions, and the fractional difference in the standard deviation of the nonrandomness between the radial and antiradial views for the IDC cases was 59% smaller than the values for other lesions. Conclusion: Preliminary results indicate that the spatial distribution of scatterers within IDCs is more homogeneously random compared to other lesions. However, inter-case variability was comparable to the median values. Future work will expand the population and use beam steered acquisitions to test for anisotropy in these features. This work was supported, in part, by NIH (grants R01CA111289, R21HD061896, R21HD063031, and R01HD072077) and the Consejo Nacional de Ciencia y Tecnologia of Mexico (Reg. 206414).

SU-E-T-75: Application of Film Dosimetry and Comparison to Delta4 to Patient-Specific Preclinical Dosimetric Verification of RapidArc

Purpose: Radiotherapy treatment modalities are becoming more complex in order to enable advanced patient treatments with a higher dose to irregularly shaped tumor volumes while sparing nearby organs at risk. VMAT as well as RapidArc incorporate capabilities such as variable doserate, variable gantry speed, and accurate and fast dynamic multileaf collimators (DMLC), to optimize dose conformity, delivery efficiency, accuracy and reliability. There is very little information on QA systems and techniques regarding the patient‐specific QA. Therefore, we compared the results obtained with radiographic film to those from the Delta4 phantom. Methods: RapidArc treatment plans were generated using the Varian Eclipse treatment planning software version 8.9 (Varian Medical Systems, Palo Alto, CA). A single but complete (358°) RapidArc was planned. RapidArc treatment plans were delivered to the Delta4 (Delta4) cylindrical (1069 p‐Si Silicon diodes) phantom from Scandidos Uppsala, Sweden, as well as to an equivalent home‐made polyethylene (HD 1000) cylindrical phantom (two longitudinal halves, density 0.94 g/cm3) for EDR2 film dosimetry. Results: The correspondence between D4 and cylindrical phantom measured were analyzed in radial and longitudinal (GT) profiles. The film in the 40° plane displayed a ±3.1% agreement in radial and a 2.2% agreement in GT direction with Delta4 phantom. A small difference was found between the planes because the cylindrical phantom joining the two halves parts has some gaps which might generate the discrepancy between radial and GT direction. The film‐measured dose in the isocenter of the 50° radial and GT plane showed an agreement within ±2.7% with the Delta4 phantom. Conclusion: Film dosimetry validated the Delta4 measurements and it clearly provided more useful information than single point dose measurement. GHENT UNIVERSITY BOF08/DOS/052

Investigation of the flow characteristics in a multirow finned-tube heat exchanger model by means of PIV measurements

Multirow plain fin-and-tube heat exchangers (PFTHEs) are widely encountered in industrial processes. The airflow between the interfin spaces generates three-dimensional vortical structures at fin–tube junctions which increase local flow mixing. In this paper, two-components PIV velocity measurements were used to investigate the flow characteristics in a model of a four-row staggered PFTHE at Reynolds number ReD=2000. For each row, the flow structure was analyzed in radial planes at the fin–tube junction in order to characterize the spatial evolution of the vortical structures around the tube. These vortical structures generated in the vicinity of fin–tube junctions were visualized by analyzing the velocity gradient tensor and their spatial evolution and dissipation was characterized. This study highlights the complexity of both row-by-row and angular evolutions of the flow structure. Significant vorticity concentration was found in the vicinity of fin–tube junctions, in the flow core where horseshoe vortices develop. The maximum primary vortex strength throughout the heat exchanger model is observed at the second fin–tube junction.

Experiments on the effective compliance in the radial–tangential plane of Norway spruce

Analysis and design of wood based composites and structures need reliable experimental compliance of their constituting materials. Therefore, an experimental method is presented to determine all of the effective in-plane elastic parameters and applied to Norway spruce specimens in the radial tangential RT plane due to the use of this species in wide variety of engineering applications. For the purpose, uni-axial compression experiments are conducted on the specimens for different material orientations under the assumptions of small strains and small rotations. Boundary extremes of the specimens are allowed to rotate for minimizing the boundary artifacts and providing near-ideal specimen deformation. During these experiments, digital image correlation is used to obtain the displacement and strain fields whilst the stress is computed through the applied load and specimen geometry. In addition to the common practice of tabulated parameters for each nominal material orientation, the experiment results are further processed through the transformation rule and least squares function. Consequently, the effective elastic parameters in the RT plane are obtained by taking general anisotropic linear elasticity into account and the material classification is performed. By means of the current method, it is expected to advance the effective in-plane compliance measurements of natural cellular materials.

Adaptive Plasticity Model for Bucket Foundations

AbstractBased on experimental investigations, the literature proposes different methods for modeling the behavior and capacity of foundations subjected to combined loading. Generally, two methods are used to predict the behavior of foundations: traditional approaches and hardening plasticity solutions. The first method is only capable of determining the capacity of the foundations and not the prepeak behavior. Thus, a new strain-hardening criterion is developed by calibrating failure criteria by employing data from small-scale tests on bucket foundations subjected to static loads. The shape of the yield, potential, and failure surfaces are found to be dependent on the embedment ratio (i.e., ratio of skirt length to the diameter) and load path. For the models tested, associated flow is observed to be plausible in the radial planes, whereas nonassociated flow is observed in the planes along the V-axis.

Numerical Investigation of Airflow in a Swirling Fluidized Bed

A numerical investigation via commercial Computational Fluid Dynamic (CFD) package, FLUENT, was carried out to investigate the aerodynamic characteristics of air flow in a Swirling Fluidized Bed (SFB). The study focused on the distributor blade configurations whereby the effect of number of blades and blade inclination in radial plane were investigated. Twelve configurations were simulated at 30, 45 and 60 blades for four radial inclinations, 0, 10, 13.5 and 15°. Two criterions were taken as performance characteristics to evaluate each configuration namely the uniformity of tangential velocity distribution and pressure drop. High uniformity at the distributor outlet will ensure uniform solid-gas contact in the actual system while low pressure drop is vital to minimize power consumption in the system. From the results, it was evident that the 30 blades with 10E radial inclination of distributor blade in plenum chamber offer the best configuration for actual application.

Cam and Pincer Femoroacetabular Impingement: CT Findings of Features Resembling Femoroacetabular Impingement in a Young Population Without Symptoms

The purpose of this study was to use CT to determine the presence of radiologic parameters associated with cam and pincer femoroacetabular impingement (FAI) in a young population without symptoms. A retrospective review of 50 patients (age range, 20-40 years) with no current or previous hip disorder who underwent CT of the abdomen and pelvis was conducted. Multiplanar images were reformatted with a soft-tissue and bone algorithm and assessed for the presence of parameters associated with FAI; alpha angle greater than 55°, femoral head-neck offset less than 8 mm, angle of acetabular version less than 15°, lateral center edge angle greater than 40°, acetabular index less than 0°, pistol-grip deformity, acetabular crossover, and prominent posterior wall signs. At least one abnormal parameter was present in 66% of joints, and two or more abnormal parameters were present in 29% of joints. In seven patients the findings were bilateral. Parameters of mixed morphologic characteristics (cam and pincer) were found in 22% of joints. In side-by-side comparison, high alpha angles were seen in 36 joints measured in the radial plane compared with only three joints measured in the axial oblique plane. The CT finding of FAI-like features was made with high frequency in a young symptom-free population. Cutoff values for defining morphologic abnormalities associated with FAI may have been set too low in the current literature. Alpha angle measurements in the radial plane may be a more accurate quantitative assessment of asphericity of the femoral head-neck junction than are measurements in the axial oblique plane.

Three-dimensional dynamic assessment of tricuspid and mitral annuli using cardiovascular magnetic resonance

To explore the potentiality of cardiovascular magnetic resonance (CMR) in the quantitative evaluation of mitral valve annulus (MVA) and tricuspid valve annulus (TVA) morphology and dynamics. CMR was performed in 13 normal subjects and 9 patients with mitral (n = 7) or tricuspid regurgitation (n = 2), acquiring cine-images in 18 radial long-axis planes passing through the middle of MVA or TVA. A novel algorithm was used to obtain dynamic three-dimensional (3D) reconstruction of MVA and TVA. Analysis was feasible in all cases, allowing accurate 3D annular reconstruction and tracking. The 3D area increased from systole [MVA, median = 10.0 cm(2) (first quartile = 8.6, third quartile = 11.4); TVA, 11.2 cm(2) (8.8-13.2)] to diastole [MVA, 10.6 cm(2) (9.4, 11.7); TVA, 11.9 cm(2) (9.2-13.5)], with TVA larger than MVA. While the longest diameter showed similar systolic and diastolic values, the shortest diameter elongated from systole [MVA, 30 mm (29-33); TVA, 33 mm (31-36)] to diastole [MVA, 31 mm (29-32); TVA, 36 mm (33-39)]. Also, TVA became more circular than MVA. TVA showed lower peak systolic excursion in the septal [15.9 mm (13.0-18.5)] and anterior regions [17.9 mm (12.2-20.7)] compared with the posterior [21.9 mm (18.6-24.0)] segment. Values in MVA were smaller than in TVA, slightly higher in anterior [11.2 mm (9.5-13.0)] than in posterior [12.4 mm (10.2-14.6)] segments. Valvular regurgitation was associated with enlarged, flattened, and more circular annuli. The applied method was feasible and accurate in normal and regurgitant valves, and may potentially have an impact on diagnosis, improvement of surgical techniques and design of annular prostheses.

Relationship Between the Anatomical Structure and the Swelling of Conditioned Wood Surfaces

The influence of swelling on the roughness of rehydrated, machinery-treated wood surfaces of Millettia laurentii De Wild. (Wengé) was studied under controlled climate conditions. The surface roughness of transverse, radial, and tangential planes was quantified by high resolution laserscan measurements with an accuracy of ±2 μm and an optical resolution of 8 × 50 μm. The surface profiles were compared with the anatomical structure of the xylem in the surface layer of the samples. The surface roughness of swollen samples increased significantly compared to unswollen samples. Higher surface roughness was found on swollen radial and tangential planes compared to swollen transverse planes. The high increase in roughness of conditioned radial and tangential planes was due to the higher swelling of tissue zones dominated by fibres compared to zones dominated by axial parenchyma, ray parenchyma, and vessels. In thinner rehydrated samples the surface roughness was lower than in thicker samples. Although the increase of surface roughness of the rehydrated samples was only in the range of 10 to 60 μm in these experiments, the gloss level of rehydrated coated surfaces decreased significantly. The results are discussed with special regard to high quality surface finishing of wooden furniture.

Automatic measuring system for railroad wheels

This paper presents a vision system to measure the wear of the railroad wheels, developed for the Portuguese railway company, CP - Comboios Portugal. The developed system is based on image-processing techniques to measure automatically the railroad wheels. The wheel's profile is acquired by the illumination of the wheel through a secant horizontal light plane. The profile's image is processed by identifying the line of the greatest light gradient. The gradient's profile is then converted to the wheel's radial profile by means of a coordinate transformation model, which transforms the image plane into the wheel's radial plane. A 1 : 1 scale static prototype is built and the calibration and testing procedures are shown. Experimental results are presented and discussed. Future improvements on the developed prototype will allow dynamic measurements at slow speeds 5 km/h, as the present developed image system was designed to eliminate distortions owing to the wheel's movement.

A model of the generation and transport of ozone in high-tension nozzle driven corona inside a novel diode

The genesis and transport of ozone (O(3)) are investigated in a novel plasma diode and described in this paper. The innovative cathode (K) of this axial symmetric diode which operated at the high voltage (φ(0)), has a large number of sharpened nozzles located on different radial planes of its central tubular-mast and is encircled by the anode (A). The nozzles played the dual role of oxygen (O(2)) injection as well as creation of high electric field (E) in the A-K gap, enabled the formation of a cold corona. Electrons in the corona under the influence of E moved towards anode, collided with O(2) and created the O radicals. O in turn joined the free O(2) and formed O(3). The evolution of O(3) here is modeled in various O(2) pressure (P), electron density (n(e)), and temperature (T) in terms of the major reaction modes involving e, O, O(2), and O(3). Typical steady state O(3) density attained so in P ~ bar, n(e) ~ 10(15) m(-3) and T ~ 300 K is over 10(25) m(-3) and that of O lower ~10(20) m(-3). Both the O and O(3) densities increased with an enhanced n(e) of avalanche multiplications in corona. O(3) increased also with a higher P but the temporal O reversed in trend midway and reduced with P towards the steady state. A sharp decline in diode resistance with smaller A-K gap induced finite discharge current and led to the undesired heating of corona. It is shown that the O(3) density reduced with the temperature rise but O density reduced with the T rise up to 500 K and then rose modestly with the further T increase.

Do the effects of high intensity 40 km cycling upon left ventricular function and cardiac biomarker during recovery vary with time of day?

Twelve healthy participants performed two identical high-intensity 40 km cycling trials (morning and evening) under controlled laboratory conditions. Echocardiograms and venous blood samples were collected before and after each exercise bout. Cardiac electro-mechanical-delay (cEMD) was measured as QRS-complex onset to peak systolic (S’) and early diastolic (E’) tissue velocities. Myocardial strain and strain rates were assessed in longitudinal, circumferential and radial planes at the left ventricular apex and base. Cardiac troponin I (cTnI) and N-terminal Pro-Brain Natriuretic Peptide (NT-proBNP) were assessed as biomarkers of cardiomyocyte damage and wall stress. cEMD was lengthened after both morning (S’: 160 ± 30 vs. 193 ± 27; E’: 478 ± 60 vs. 620 ± 87, P < 0.05) and evening (S’: 155 ± 29 vs. 195 ± 31; E’: 488 ± 42 vs. 614 ± 61, P < 0.05) trials. A reduction in peak S’ (morning: 6.96 ± 1.12 vs. 6.66 ± 0.89; evening: 7.09 ± 0.94 vs. 7.02 ± 0.76) was correlated with cEMD (r = −0.335, P < 0.05). Peak longitudinal strain was reduced, atrial strain rates were sporadically increased in both trials post-cycling. cTnI was elevated in only two participants (0.04 µg · L−1, 0.03 µg · L−1), whilst NT-proBNP was below the clinical cut-off point in all participants. Prolonged-cycling resulted in a lengthening of cEMD, small changes in aspects of left ventricular deformation and sporadic increases in cardiac biomarkers. None of these effects were moderated by time-of-day.