scholarly journals Soft tissue Absorption Tomography with Correction for Scattering Aberrations

2005 ◽  
Vol 27 (4) ◽  
pp. 221-236
Author(s):  
Emilie Franceschini ◽  
Marie-Christine Pauzin ◽  
Serge Mensah ◽  
Jean-Philippe Groby
Keyword(s):  
Sound Speed ◽  
Soft Tissues ◽  
A Priori ◽  
Tomographic Reconstruction ◽  
Estimation Procedure ◽  
Transmission Tomography ◽  
Reconstruction Procedure ◽  
Scattering Effects ◽  
Ultrasonic Propagation ◽  
The Many

Among the many factors involved in ultrasound attenuation phenomena, scattering effects play a major role, even in the unexpected case of soft tissues. It is proposed in this study to quantitatively evaluate the scattering affecting the measurements before reconstructing the absorption parameter alone. The reconstruction procedure involves three steps: (1) Estimating the sound speed map using a transmission tomography algorithm. This estimation procedure provides a numerical phantom of the organ probed, cleared of all dissipative components. This absorption free phantom mimics the (viscoacoustic) tissues imaged except for the density and absorption characteristics: the density a priori equals 1000 kg/m3 and the absorption is not taken into account. The impedance fluctuations in the object are therefore approximated on the basis of the sound speed contrast. (2) Synthesing the field scattered by the absorption free phantom; the attenuation observed here results solely from the scattering phenomenon. The synthesis is carried out using a finite-element time domain code simulating the ultrasonic propagation through the phantom. It provides the scattering distortion reference introduced into the log spectral absorption estimator. (3) Reducing the scattering distortions affecting the integrated absorption measured along the ray paths using a log spectral procedure. The corrected integrated absorption is then processed using a tomographic reconstruction procedure that provides an estimate of the absorption distribution. Simple numerical simulations show the improvement obtained in the absorption estimates with this approach.

scholarly journals CALCULATION OF MEASUREMENTS UNCERTAINTY AT CARRYING OUT OF BALLISTIC RESEARCHES

2017 ◽  
Vol 17 ◽  
pp. 236-245
Author(s):  
V. V. Kozhevnikov
Keyword(s):  
A Priori ◽  
Quantitative Description ◽  
Estimation Procedure ◽  
Standard Uncertainty ◽  
Uncertainty Estimation ◽  
Measured Quantity ◽  
Expanded Uncertainty ◽  
Uncertainty Sources ◽  
Multiple Observations ◽  
Uncertainty Calculation

Today one of the priority problems is receiving an accreditation certificate under the international standard ISO/IEC 17025:2006 by measurement laboratories of Expert service subdivision of the Ministry of Internal Affairs of Ukraine. One of the requirements which is shown to the accredited testing laboratories, is a presence of uncertainty estimation procedure and ability to apply it. As the ballistic researches are one of the important directions of researches which are carried out in the expert subdivisions, therefore the paper is devoted to the consideration ofa question of uncertainty calculation in such measurements. In the mathematical statistics two types of paramètres which characterize dispersion of not correlated random variables are known: a root-mean-square deviation and a confidential interval. As the characteristics of uncertainty they are applied under the title standard and expanded uncertainty. An elementary estimation of measurements result and its uncertainty is carried out in such an order: description of the measured quantity; revealing of uncertainty sources; quantitative description uncertainty constituents (there are estimated uncertainty constituents which can be received a posteriori or a priori); calculation of standard uncertainty of each source, total standard uncertainty and expanded uncertainty. A posterior estimation is possible only in the case of carrying out multiple observations of the measured quantity (standard uncertainty of type A). An a priori estimation is carried out when multiple observations are not performed. In this case it’s necessary to use the information received from the measurements performed before, from the passport data on the facilities ofmeasuring technics orfrom reference books (standard uncertainty of type B). Short consideration of uncertainty concept, elucidation of the basic stages measurements result estimation and its uncertainty gives the chance to transform the theoretical knowledge into practical application of uncertainty estimation on examples of measurements uncertainty calculation during carrying out ballistic ammunition researches by two different ways.

Gas Turbine Exhaust Emissions Monitoring Using Nonintrusive Infrared Spectroscopy

1998 ◽  
Vol 120 (3) ◽  
pp. 514-518 ◽  
Author(s):  
M. Hilton ◽  
A. H. Lettington ◽  
C. W. Wilson
Keyword(s):  
Gas Turbine ◽  
Molecular Species ◽  
Tomographic Reconstruction ◽  
Emission Spectra ◽  
Exhaust Emissions ◽  
Infrared Emission ◽  
High Spectral Resolution ◽  
Rotational Line ◽  
Spectroscopic Techniques ◽  
Reconstruction Procedure

Infrared (IR) spectra of the exhaust emissions from a static gas turbine engine have been studied using Fourier Transform (FT) spectroscopic techniques. Passive detection of the infrared emission from remote (range ∼ 3 m) hot exhaust gases was obtained nonintrusively using a high spectral resolution (0.25 cm−1) FTIR spectrometer. Remote gas temperatures were determined from their emission spectra using the total radiant flux method or by analysis of rotational line structure. The HITRAN database of atmospheric species was used to model the emission from gas mixtures at the relevant temperatures. The spatial distribution of molecular species across a section transverse to the exhaust plume ∼10 cm downstream of the jet pipe nozzle was studied using a tomographic reconstruction procedure. Spectra of the infrared emission from the plume were taken along a number of transverse lines of sight from the centerline of the engine outwards. A mathematical matrix inversion technique was applied to reconstruct the molecular concentrations of CO and CO2 in concentric regions about the centerline. Quantitative measurement of the molecular species concentrations determined nonintrusively were compared with results from conventional extractive sampling techniques.

The Impact of the Court of Justice of the European Union on Neighbouring Countries

2020 ◽  
pp. 349-396
Author(s):  
Arie Reich ◽  
Hans-W. Micklitz
Keyword(s):  
European Union ◽  
A Priori ◽  
Policy Recommendations ◽  
Eu Law ◽  
The European Union ◽  
The Third ◽  
Court Of Justice ◽  
The Many ◽  
The Impact ◽  
Legal Integration

The concluding chapter sums up the overall findings of the project through three different strands of analysis: the first breaks down the eleven jurisdictions into three groups based on the relative quantity and impact of Court of Justice of the European Union (CJEU) citations found in these jurisdictions. By drawing conclusions from all the country reports through a comparative and macro-perspective, the goal is to distil the insights of the entire project and formulate policy recommendations in the light of EU external policy and legal integration objectives vis-à-vis its neighbourhood; the second examines the many factors that a priori could have an impact on whether judges are likely to cite the CJEU in their judgments, and then discusses what the research has found in relation to the actual role played by these factors; the third tries to place the current project into the context of overall research on the global reach of EU law, which can be ‘exported’ to non-members of the EU through various mechanisms, such as mutual and formal agreement or through more unilateral and spontaneous forms. They include modes of extraterritorial application of EU law, territorial extension, and the so-called ‘Brussels Effect’. The chapter concludes with some general observations and thoughts and formulates possible policy recommendations.

Positron emission tomographic analysis of cerebral structures activated specifically by repetitive noxious heat stimuli

1994 ◽  
Vol 71 (2) ◽  
pp. 802-807 ◽  
Author(s):  
K. L. Casey ◽  
S. Minoshima ◽  
K. L. Berger ◽  
R. A. Koeppe ◽  
T. J. Morrow ◽  
...  
Keyword(s):  
A Priori ◽  
Estimation Procedure ◽  
Subjective Rating ◽  
Positron Emission Tomographic ◽  
Noxious Heat ◽  
Heat Sensation ◽  
Medial Dorsal ◽  
Subjective Intensity ◽  
Positron Emission ◽  
Tomographic Analysis

1. To identify the forebrain and brain stem structures that are active during the perception of acute heat pain in humans, we performed H2 15O positron emission tomographic (PET) analyses of cerebral blood flow (CBF) on nine normal volunteers while they received repetitive noxious (50 degrees C) and innocuous (40 degrees C) 5 s heat pulses to the forearm (average resting temperature of 31.8 degrees C). Each subject rated the subjective intensity of each stimulation series according to a magnitude estimation procedure in which 0 = no heat sensation, 7 = barely painful, and 10 = barely tolerable. 2. Three scans were performed at each temperature. Mean CBF images were created for each experimental condition and oriented onto standardized stereotaxic coordinates. Subtraction images were created between conditions for each subject and averaged across subjects. Volumes of interest (VOI) were chosen, based on a priori hypotheses and the results of previously published PET studies. In addition, a separate statistical summation analysis of individual voxels was performed. Statistical thresholds were established with corrections for multiple comparisons. 3. Significant CBF increases to 50 degrees C stimuli were found in the contralateral thalamus, cingulate cortex, S2 and S1 cortex, and insula. The ipsilateral S2 cortex and thalamus, and the medial dorsal midbrain and cerebellar vermis also showed significant CBF increases. All subjects rated the 50 degrees C stimuli as painful (average subjective rating = 8.9 +/- 0.9 SD) and the 40 degrees C stimuli as warm, but not painful (average subjective rating = 2.1 +/- 1.0).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Distributions of Hyper-Local Configuration Elements to Characterize, Compare, and Assess Landscape-Level Spatial Patterns

Entropy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 420
Author(s):  
Tarmo K. Remmel
Keyword(s):  
A Priori ◽  
Simulated Data ◽  
Generic Model ◽  
Regular Grid ◽  
First Order ◽  
Local Configuration ◽  
Leibler Divergence ◽  
Common Framework ◽  
Novel Method ◽  
The Many

Even with considerable attention in recent decades, measuring and working with patterns remains a complex task due to the underlying dynamic processes that form these patterns, the influence of scales, and the many further implications stemming from their representation. This work scrutinizes binary classes mapped onto regular grids and counts the relative frequencies of all first-order configuration components and then converts these measurements into empirical probabilities of occurrence for either of the two landscape classes. The approach takes into consideration configuration explicitly and composition implicitly (in a common framework), while the construction of a frequency distribution provides a generic model of landscape structure that can be used to simulate structurally similar landscapes or to compare divergence from other landscapes. The technique is first tested on simulated data to characterize a continuum of landscapes across a range of spatial autocorrelations and relative compositions. Subsequent assessments of boundary prominence are explored, where outcomes are known a priori, to demonstrate the utility of this novel method. For a binary map on a regular grid, there are 32 possible configurations of first-order orthogonal neighbours. The goal is to develop a workflow that permits patterns to be characterized in this way and to offer an approach that identifies how relatively divergent observed patterns are, using the well-known Kullback–Leibler divergence.

scholarly journals Reducing Nasopharyngeal Trauma: The Urethral Catheter–Assisted Nasotracheal Intubation Technique

2011 ◽  
Vol 58 (1) ◽  
pp. 26-30 ◽  
Author(s):  
Allen Wong ◽  
Paul Subar ◽  
Heidi Witherell ◽  
Konstantin J Ovodov
Keyword(s):  
Soft Tissues ◽  
Nasotracheal Intubation ◽  
Mouth Opening ◽  
Urethral Catheter ◽  
Alternative Methods ◽  
Nasal Intubation ◽  
Intubation Technique ◽  
Invasive Approach ◽  
Dental Procedures ◽  
The Many

Nasal intubation is an advantageous approach for dental procedures performed in the hospital, ambulatory surgery center, or dental office, when possible. Although many who provide anesthesia services are familiar and comfortable with nasal intubation techniques, some are reluctant and uncomfortable because of lack of experience or fear of nasopharyngeal bleeding and trauma. It has been observed from experiences in various settings that many approaches may be adapted to the technique of achieving nasal intubation. The technique that is described in this paper suggests a minimally invasive approach that introduces the nasoendotracheal tube through the nasopharyngeal pathway to the oropharynx in an expedient manner while preserving the nasopharyngeal structures, thus lessening nasal bleeding and trauma to soft tissues. The technique uses a common urethral catheter and can be incorporated along with current intubation armamentaria. As with all techniques, some limitations to the approach have been identified and are described in this paper. Cases with limited mouth opening, neck injury, and difficult airways may necessitate alternative methods. However, the short learning curve along with the many benefits of this technique offers the anesthesia professional additional options for excellent patient care.

Electron Crystallographic Structure of the Limulus Acrosomal Bundle at 20 Å Resolution

2000 ◽  
Vol 6 (S2) ◽  
pp. 242-243
Author(s):  
Michael B. Sherman ◽  
Guichy Waller ◽  
Paul Matsudaira ◽  
Wah Chiu ◽  
Michael F. Schmid
Keyword(s):  
Tomographic Reconstruction ◽  
Crystallographic Analysis ◽  
Crystallographic Structure ◽  
Reconstruction Procedure ◽  
Electron Dose ◽  
The Core ◽  
Cell Spacing ◽  
Crystallographic Symmetry ◽  
Tilt Series

Limulus sperm contains a dynamic macromolecular structure that rapidly extends a 50-μum process called the true discharge. The core of this structure is a bundle of ordered filaments composed of a complex of actin, scruin and calmodulin. We have shown that small segments along the bundle can be treated as single crystals with a unit cell spacing of 144 × 144 × 766 Å. A tomographic reconstruction of the bundle was done from multiple tilt series of images to ∼40 Å resolution. To extend the structural determination of the bundle at a higher resolution, we have used electron crystallographic analysis of single images of the bundles preserved in vitreous ice. Furthermore, we did not employ any helical or crystallographic symmetry (other than PI) in the reconstruction procedure.Acrosomal bundles from Limulus sperm cells were purified as described earlier. Images of frozen hydrated bundles were taken at 40,000x EM magnification in a JEOL 4000EX electron cryomicroscope using an electron dose of 6 - 10 electrons/Å2.

Migration moveout analysis and depth focusing

Geophysics ◽  
1993 ◽  
Vol 58 (1) ◽  
pp. 91-100 ◽  
Author(s):  
Claude F. Lafond ◽  
Alan R. Levander
Keyword(s):  
Heterogeneous Media ◽  
A Priori ◽  
Complex Structure ◽  
Tomographic Reconstruction ◽  
Synthetic Data ◽  
Real Data ◽  
Velocity Model ◽  
Velocity Analysis ◽  
Data Set ◽  
Velocity Models

Prestack depth migration still suffers from the problems associated with building appropriate velocity models. The two main after‐migration, before‐stack velocity analysis techniques currently used, depth focusing and residual moveout correction, have found good use in many applications but have also shown their limitations in the case of very complex structures. To address this issue, we have extended the residual moveout analysis technique to the general case of heterogeneous velocity fields and steep dips, while keeping the algorithm robust enough to be of practical use on real data. Our method is not based on analytic expressions for the moveouts and requires no a priori knowledge of the model, but instead uses geometrical ray tracing in heterogeneous media, layer‐stripping migration, and local wavefront analysis to compute residual velocity corrections. These corrections are back projected into the velocity model along raypaths in a way that is similar to tomographic reconstruction. While this approach is more general than existing migration velocity analysis implementations, it is also much more computer intensive and is best used locally around a particularly complex structure. We demonstrate the technique using synthetic data from a model with strong velocity gradients and then apply it to a marine data set to improve the positioning of a major fault.

Scattering Tomography and Its Application to Sooting Diffusion Flames

1994 ◽  
Vol 116 (1) ◽  
pp. 144-151 ◽  
Author(s):  
M. P. Mengu¨c¸ ◽  
P. Dutta
Keyword(s):  
Diffusion Flames ◽  
Tomographic Reconstruction ◽  
Scattering Coefficient ◽  
Reconstruction Technique ◽  
Transmission Tomography ◽  
Ion Laser ◽  
Series Of Experiments ◽  
Argon Ion ◽  
Good Agreement

A new analytical tomographic reconstruction technique was developed for the determination of the extinction and scattering coefficient distributions in axisymmetric media. This method, called “scattering tomography,” was tested for several particle concentration profiles corresponding to those for diffusion flames. After that, a series of experiments were performed on sooting acetylene flames using an argon-ion laser nephelometer. The experimental results were reduced using both the transmission and scattering tomography techniques to obtain the extinction coefficient profiles. It was shown that in the center of the flame, the results from these two approaches were in good agreement. Scattering tomography can be used to determine both the absorption and scattering coefficient distributions in the medium. In addition to that, it is preferable over the transmission tomography if the medium is optically very thin and particles are predominantly scattering.

The role of arterio-venous anastomoses in the neutrophilic granulocytes circulation

2017 ◽  
Vol 25 (1) ◽  
pp. 10-14 ◽  
Author(s):  
Igor Markov ◽  
Valeriya Markova ◽  
Tat'yana Malykhina ◽  
Matvey Sofronov ◽  
Yanis Antonyan ◽  
...  
Keyword(s):  
Soft Tissues ◽  
A Priori ◽  
Systemic Circulation ◽  
Universal Method ◽  
Main Function ◽  
Neutrophilic Granulocytes ◽  
Paraffin Sections ◽  
No Reflow Phenomenon ◽  
Facial Soft Tissues

Migration of neutrophilic granulocytes (NG), whose main function is phagocytosis, is primarily caused by the venule lumen. Nevertheless, NGs are often “blamed” for their ability to block microcirculation in the systemic circulation and thus to develop the no-reflow phenomenon in the cerebrum and myocardium. Apparently, NGs are a priori believed to enter the venous bed trans capillary, although their morphological features should prevent it. Are NGs able to circulate into venules via arterio-venous anastomoses (AVA)? The aim of the research is to elucidate the role of AVA in neutrophilic granulocyte circulation. The paper presents the study of the intestine, skeletal muscles, myocardium, cerebrum, peritoneum, and spleen in cats (n=7) and white rates (n=17). The research methods are intravascular impregnation by the Ranvier method, a universal method of impregnation with various silver salts, routine histological methods of staining paraffin sections. In intact animals, neutrophilic granulocytes enter the venules via AVAs only. In the myocardium and cerebrum, which have no AVAs, due to the blood separation phenomenon, NGs enter the epicardium exclusively in the former case and the facial soft tissues and pachymeninx in the latter.

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