scholarly journals Compressed SENSE in Pediatric Brain Tumor MR Imaging

2022 ◽  
Author(s):  
Rieke L. Meister ◽  
Michael Groth ◽  
Julian H. W. Jürgens ◽  
Shuo Zhang ◽  
Jan H. Buhk ◽  
...  
Keyword(s):  
Brain Tumor ◽  
Image Quality ◽  
Total Energy ◽  
Energy Release ◽  
Pediatric Brain Tumor ◽  
Total Energy Release ◽  
Post Contrast ◽  
Energy Deposit ◽  
Examination Time ◽  
Pediatric Brain

Abstract Purpose To compare the image quality, examination time, and total energy release of a standardized pediatric brain tumor magnetic resonance imaging (MRI) protocol performed with and without compressed sensitivity encoding (C-SENSE). Recently introduced as an acceleration technique in MRI, we hypothesized that C‑SENSE would improve image quality, reduce the examination time and radiofrequency-induced energy release compared with conventional examination in a pediatric brain tumor protocol. Methods This retrospective study included 22 patients aged 2.33–18.83 years with different brain tumor types who had previously undergone conventional MRI examination and underwent follow-up C‑SENSE examination. Both examinations were conducted with a 3.0-Tesla device and included pre-contrast and post-contrast T1-weighted turbo-field-echo, T2-weighted turbo-spin-echo, and fluid-attenuated inversion recovery sequences. Image quality was assessed in four anatomical regions of interest (tumor area, cerebral cortex, basal ganglia, and posterior fossa) using a 5-point scale. Reader preference between the standard and C‑SENSE images was evaluated. The total examination duration and energy deposit were compared based on scanner log file analysis. Results Relative to standard examinations, C‑SENSE examinations were characterized by shorter total examination times (26.1 ± 3.93 vs. 22.18 ± 2.31 min; P = 0.001), reduced total energy deposit (206.0 ± 19.7 vs. 92.3 ± 18.2 J/kg; P < 0.001), and higher image quality (overall P < 0.001). Conclusion C‑SENSE contributes to the improvement of image quality, reduction of scan times and radiofrequency-induced energy release relative to the standard protocol in pediatric brain tumor MRI.

Measurement of the Total Energy Release Rate for Cracks in PZT Under Combined Mechanical and Electrical Loading

2007 ◽  
Vol 74 (6) ◽  
pp. 1197-1211 ◽  
Author(s):  
H. Jelitto ◽  
F. Felten ◽  
M. V. Swain ◽  
H. Balke ◽  
G. A. Schneider
Keyword(s):  
Total Energy ◽  
Energy Release Rate ◽  
Energy Release ◽  
Crack Growth ◽  
Electric Fields ◽  
Release Rate ◽  
Total Energy Release ◽  
Custom Made ◽  
Poling Direction ◽  
Total Energy Release Rate

Four-point-bending V-notched specimens of lead zirconate titanate (PZT) poled parallel to the long axis are fractured under conditions of controlled crack growth in a custom-made device. In addition to the mechanical loading electric fields, up to 500V∕mm are applied parallel and anti-parallel to the poling direction, i.e., perpendicular to the crack surface. To determine the different contributions to the total energy release rate, the mechanical and the piezoelectric compliance, as well as the electrical capacitance of the sample, are recorded continuously using small signal modulation/demodulation techniques. This allows for the calculation of the mechanical, the piezoelectric, and the electrical part of the total energy release rate due to linear processes. The sum of these linear contributions during controlled crack growth is attributed to the intrinsic toughness of the material. The nonlinear part of the total energy release rate is mostly associated to domain switching leading to a switching zone around the crack tip. The measured force-displacement curve, together with the modulation technique, enables us to determine this mechanical nonlinear contribution to the overall toughness of PZT. The intrinsic material toughness is only slightly dependent on the applied electric field (10% effect), which can be explained by screening charges or electrical breakdown in the crack interior. The part of the toughness due to inelastic processes increases from negative to positive electric fields by up to 100%. For the corresponding nonlinear electric energy change during crack growth, only a rough estimate is performed.

scholarly journals Heat Release Rate Characterization of NFPA 1403 Compliant Training Fuels

2021 ◽  
Author(s):  
John W. Regan
Keyword(s):  
Total Energy ◽  
Heat Release ◽  
Energy Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Quantitative Methods ◽  
Linear Regression Analysis ◽  
Total Energy Release ◽  
Fuel Mass ◽  
Initial Fuel

AbstractWhen using solid fuels for live fire training, NFPA 1403: Standard on Live Fire Training Evolutions requires that the materials be wood based. While the standard offers guidance on the type of fuels that are permissible for use in training, it offers little in the way of quantitative methods of selecting an appropriately sized fuel package. In order to examine the effects of fuel mass and orientation on heat release behavior, free burn heat release rate (HRR) experiments were conducted on twenty-one wood-based training fuel packages and twelve comparison furniture items. Training fuel packages demonstrated peak HRRs ranging from 1.0 MW to 3.6 MW, with the total energy release between 210 MJ and 1615 MJ. The furniture items exhibited peak HRRs between 0.9 MW and 3.7 MW, with the total energy release between 180 MJ and 995 MJ. A least-squares linear regression analysis indicated a good linear fit between total energy release and fuel mass burned among the training fuel packages (R$$^2$$ 2  $$=$$ =  0.98), suggesting that the effective heat of combustion is approximately constant at 14.2 MJ/kg. Generally, peak HRR increased as initial fuel mass increased, although the relationship was more variable, with the peak HRRs of similarly sized training fuel packages varying by nearly 1 MW. The results indicated that while total energy release was dependent largely on the initial fuel mass, peak HRR and peak burning duration were also dependent on the orientation and type of fuel in the fuel package. Wood-based training fuel packages were capable of producing peak HRRs comparable to individual items of furniture, although the total energy release was typically higher for the training fuel packages compared to corresponding furniture items.

Calorimetric study of an electrochemical reduction

1978 ◽  
Vol 56 (10) ◽  
pp. 1415-1418 ◽  
Author(s):  
Peter J. Turner ◽  
Huw O. Pritchard
Keyword(s):  
Total Energy ◽  
Current Efficiency ◽  
Energy Release ◽  
Electrochemical Reduction ◽  
Reduction Reaction ◽  
Enthalpy Change ◽  
Calorimetric Study ◽  
Total Energy Release

The aqueous trichloroacetate ion is reduced irreversibly and with unit current efficiency to the dichloroacetate ion. From the total energy release observed when this process is carried out inside a calorimeter, it is possible to deduce the enthalpy change for the reduction reaction.

scholarly journals Interpretation of the Size Spectrum of Cosmic g-ray Bursts in Terms of an Idealized Galactic Distribution of Sources

1978 ◽  
Vol 31 (2) ◽  
pp. 189 ◽  
Author(s):  
M Yoshimori
Keyword(s):  
Total Energy ◽  
Energy Release ◽  
Galactic Plane ◽  
Size Spectrum ◽  
Total Energy Release ◽  
Size Spectra ◽  
Galactic Distribution

A model for the size spectrum of cosmic y-ray bursts is derived on the assumption that the sources of these bursts are distributed uniformly in space out to 0�3 kpc, thence uniformly in a disc (galactic plane) to 3 kpc, and thence uniformly in a line (galactic arm) to 27 kpc. Two forms are assumed for the distribution of the total energy release per burst: a gaussian with mean sand an exponential with characteristic so, such that s = So = 1032 J. The derived size spectra are in agreement with results obtained from satellite and balloon observations, thus supporting both the galactic origin of the bursts and a representative total energy release for them of 1032 J.

An Analytical Crack-Tip Element for Layered Elastic Structures

1995 ◽  
Vol 62 (2) ◽  
pp. 294-305 ◽  
Author(s):  
B. D. Davidson ◽  
Hurang Hu ◽  
R. A. Schapery
Keyword(s):  
Total Energy ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Plate Theory ◽  
Crack Tip ◽  
Total Energy Release ◽  
Linear Elastic ◽  
Crack Tip Element ◽  
Total Energy Release Rate

A previously developed linear elastic crack-tip element analysis is reviewed briefly, and then extended and refined for practical applications. The element provides analytical expressions for total energy release rate and mode mix in terms of plate theory force and moment resultants near the crack tip. The element may be used for cracks within or between homogeneous isotropic or orthotropic layers, as well as for delamination of laminated composites. Classical plate theory is used to derive the equations for total energy release rate and mode mix; a “mode mix parameter,” Ω, as obtained from a separate continuum analysis is necessary to complete the mode mix decomposition. This parameter depends upon the elastic and geometrical properties of the materials above and below the crack plane, but not on the loading. A relatively simple finite element technique for determining the mode-mix parameter is presented and convergence in terms of mesh refinement is studied. Specific values of Ω are also presented for a large number of cases. For those interfaces where a linear elastic solution predicts an oscillatory singularity, an approach is described which allows a unique, physically meaningful value of fracture mode ratio to be defined. This approach is shown to provide predictions of crack growth between dissimilar homogeneous materials that are equivalent to those obtained from the oscillatory field solution. Application of the approach to delamination in fiber-reinforced laminated composites is also discussed.

Anaerobic and aerobic relative contribution to total energy release during supramaximal effort in patients with left ventricular dysfunction

2008 ◽  
Vol 104 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Alessandro Mezzani ◽  
Ugo Corrà ◽  
Cristina Andriani ◽  
Andrea Giordano ◽  
Roberto Colombo ◽  
...  
Keyword(s):  
Total Energy ◽  
Energy Release ◽  
Left Ventricular Dysfunction ◽  
Ventricular Dysfunction ◽  
Left Ventricular ◽  
Moderate Intensity ◽  
Test Duration ◽  
Energetic Metabolism ◽  
Constant Power ◽  
Total Energy Release

Energetic metabolism during effort is impaired in patients with left ventricular dysfunction (Dysf), but data have been lacking up to now on the relative anaerobic vs. aerobic contribution to total energy release during supramaximal effort. Recently, the maximal accumulated oxygen deficit (MAOD) has been shown to be measurable in Dysf patients, making it possible to evaluate the anaerobic/aerobic interaction under conditions of maximal stress of both anaerobic and aerobic metabolic pathways in this population. Nineteen Dysf patients and 17 normal patients (N) underwent one ramp cardiopulmonary, three moderate-intensity constant-power, and three supramaximal constant-power (1- to 2-min, 2- to 3-min, and 3- to 4-min duration) exercise tests. MAOD was the difference between accumulated O2demand (accO2dem; estimated from the moderate-intensity O2uptake/watt relationship) and uptake during supramaximal tests. Percent anaerobic (%Anaer) and aerobic (%Aer) energetic release were [(MAOD/accO2dem)·100] and 100 − %Anaer, respectively. MAOD did not vary between 1–2, 2–3, and 3–4 min supramaximal tests, whereas accO2dem increased significantly with and was linearly related to test duration in both Dysf and N. Consequently, %Anaer and %Aer decreased and increased, respectively, with increasing test duration but did not differ between Dysf and N in 1–2 min, 2–3 min, and 3–4 min tests. Our study demonstrates a similar relative anaerobic vs. aerobic contribution to total energy release during supramaximal effort in Dysf and N. This finding indicates that energetic metabolism during supramaximal exercise is exercise tolerance independent and that relative anaerobic vs. aerobic contribution in this effort domain remains the same within the physiology- or pathology-induced limits to individual peak exercise performance.

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