scholarly journals Optical endovascular imaging combining endoscopy, NBI and OCT, a feasibility study

2019 ◽  
Vol 5 (1) ◽  
pp. 577-580
Author(s):  
Axel Boese ◽  
Akhil Karthasseril Sivankutty ◽  
Michael Friebe
Keyword(s):  
Blood Flow ◽  
Structural Information ◽  
Endoscopic Imaging ◽  
Camera System ◽  
Video Mode ◽  
Endoscopic Images ◽  
System A ◽  
Analysis Of The Images ◽  
Definition Of ◽  
Short Time

AbstractFor imaging of the vascular structure, angiography is state of the art. This can be done by contrast enhanced XRay, CT or MR imaging. But these modalities typically only show the blood flow and do not allow a depiction of the vasculature itself. To provide information about the vessel walls and plaques narrowing the blood flow, catheter based intra vascular ultrasound or vascular optical coherence tomography can be used. Optical endoscopic imaging is rarely used in vascular diagnosis. But endoscopic imaging can depict superficial inflammations or defects of the intima vessel layer and the real anatomical shape of the inner vasculature e.g. at bifurcations or aneurysms. Since OCT and endoscopic imaging both need a flushing to remove the blood for a short time, a combination of both modalities seems viable. For combining the two modalities, various background studies were performed including the selection of a feasible fibre endoscope, light source and camera system. A new pull-back and flushing device was designed and created for realizing the synchronous image acquisition using the two modalities. For calibration of the system and definition of the pullback and imaging parameters, first tests on artificial phantoms were performed. Then vascular and tissue models were imaged in a combined pullback mode after using the flush for complete blood removal. Endoscopic images were acquired in a video mode. The analysis of the images was done subjectively. As expected, the OCT provided structural information of the wall. The endoscopic images in combination with pullback appear blurry in video mode. The flushing liquid hinders the automatic focusing of the camera. Thus, smaller details could not be identified but bifurcations were visible. Even though the results were not good as expected, the study showed the potential of a bimodal system and addressed the issues faced in the initial implementation.

scholarly journals Magnetohydrodynamic Blood Flow in a Cylindrical Tube with Magnetic Particles: A Time Fractional Model

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Farhad Ali ◽  
Samina Majeed ◽  
Anees Imtiaz
Keyword(s):  
Blood Flow ◽  
Magnetic Particles ◽  
Mass Parameter ◽  
Classical Model ◽  
Cylindrical Tube ◽  
Definition Of ◽  
Circular Cylindrical Tube ◽  
Short Time ◽  
Applied External Magnetic Field ◽  
Fractional Parameter

The present work theoretically investigates the natural convection blood flow as a Brinkman-type fluid with uniformly distributed magnetic particles in a circular cylindrical tube with the applied external magnetic field. The classical model for the blood flow is generalized by using the definition of Caputo time-fractional derivative. The exact solutions are obtained by using the Laplace and Henkel transforms. Unlike the classical model, the obtained general results are expressed in the form of “Lorenzo and Hartley’s” and “Robotnov and Hartley’s” functions. Graphs are plotted to show the effects of different parameters on the blood flow. Furthermore, the velocity and temperature distributions are discussed in terms of memory. The effect of fractional parameter α for a long and short time has also been observed. It is noticed that blood velocity can be controlled using the fractional parameter. It is also found that, for τ > 0 , fluid and particles motion increased, and reverse behavior is observed for τ < 0 . It has been noticed that increasing values of particle mass parameter P m and magnetic parameter M slow down the motion of blood and magnetic particles. These results are helpful for effective drug delivery and regulating blood flow.

scholarly journals Duplicate detection of 2D-NMR Spectra

2007 ◽  
Vol 4 (1) ◽  
pp. 64-80 ◽  
Author(s):  
Alexander Hinneburg ◽  
Björn Egert ◽  
Andrea Porzel
Keyword(s):  
Measurement Errors ◽  
Nmr Spectra ◽  
Structural Information ◽  
Chemical Shifts ◽  
Dimensional Space ◽  
Real Data ◽  
2D Nmr ◽  
2D Nmr Spectra ◽  
Definition Of ◽  
Short Time

Abstract 2D-Nuclear magnetic resonance (NMR) spectra are used in the (structural) analysis of small molecules. In contrast to 1D-NMR spectra, 2D-NMR spectra correlate the chemical shifts of 1H and 13C at the same time. A spectrum consists of several peaks in a two--dimensional space. The most important information of a peak is the location of its center, which captures the bonding relationships of hydrogen and carbon atoms. A spectrum contains much information about the chemical structure of a product, but in most cases the structure cannot be read off in a simple and straightforward manner. Structure elucidation involves a considerable amount (manual) efforts. Using high-field NMR spectrometers, many 2D-NMR spectra can be recorded in short time. So the common situation is that a lab or company has a repository of 2D-NMR spectra, partially annotated with the structural information. For the remaining spectra the structure in unknown. In case two research labs are collaborating, the repositories will be merged and annotations shared. We reduce that problem to the task of finding duplicates in a given set of 2D-NMR spectra. Therefore, we propose a simple but robust definition of 2D-NMR duplicates, which allows for small measurement errors. We give a quadratic algorithm for the problem, which can be implemented in SQL. Further, we analyze a more abstract class of heuristics, which are based on selecting particular peaks. Such a heuristic works as a filter step on the pairs of possible duplicates and allows false positives. We compare all methods with respect to their run time. Finally we discuss the effectiveness of the duplicate definition on real data.

Precise on-line Measurement of Lattice Vectors

1990 ◽  
Vol 48 (1) ◽  
pp. 530-531
Author(s):  
W.J. de Ruijter ◽  
Sharma Renu
Keyword(s):  
Electron Microscope ◽  
Measurement Errors ◽  
Dynamic Range ◽  
Structural Information ◽  
Statistical Parameter ◽  
Systematic Errors ◽  
Geometric Distortion ◽  
Crystal Silicon ◽  
Camera System ◽  
On Line

Established methods for measurement of lattice spacings and angles of crystalline materials include x-ray diffraction, microdiffraction and HREM imaging. Structural information from HREM images is normally obtained off-line with the traveling table microscope or by the optical diffractogram technique. We present a new method for precise measurement of lattice vectors from HREM images using an on-line computer connected to the electron microscope. It has already been established that an image of crystalline material can be represented by a finite number of sinusoids. The amplitude and the phase of these sinusoids are affected by the microscope transfer characteristics, which are strongly influenced by the settings of defocus, astigmatism and beam alignment. However, the frequency of each sinusoid is solely a function of overall magnification and periodicities present in the specimen. After proper calibration of the overall magnification, lattice vectors can be measured unambiguously from HREM images.Measurement of lattice vectors is a statistical parameter estimation problem which is similar to amplitude, phase and frequency estimation of sinusoids in 1-dimensional signals as encountered, for example, in radar, sonar and telecommunications. It is important to properly model the observations, the systematic errors and the non-systematic errors. The observations are modelled as a sum of (2-dimensional) sinusoids. In the present study the components of the frequency vector of the sinusoids are the only parameters of interest. Non-systematic errors in recorded electron images are described as white Gaussian noise. The most important systematic error is geometric distortion. Lattice vectors are measured using a two step procedure. First a coarse search is obtained using a Fast Fourier Transform on an image section of interest. Prior to Fourier transformation the image section is multiplied with a window, which gradually falls off to zero at the edges. The user indicates interactively the periodicities of interest by selecting spots in the digital diffractogram. A fine search for each selected frequency is implemented using a bilinear interpolation, which is dependent on the window function. It is possible to refine the estimation even further using a non-linear least squares estimation. The first two steps provide the proper starting values for the numerical minimization (e.g. Gauss-Newton). This third step increases the precision with 30% to the highest theoretically attainable (Cramer and Rao Lower Bound). In the present studies we use a Gatan 622 TV camera attached to the JEM 4000EX electron microscope. Image analysis is implemented on a Micro VAX II computer equipped with a powerful array processor and real time image processing hardware. The typical precision, as defined by the standard deviation of the distribution of measurement errors, is found to be <0.003Å measured on single crystal silicon and <0.02Å measured on small (10-30Å) specimen areas. These values are ×10 times larger than predicted by theory. Furthermore, the measured precision is observed to be independent on signal-to-noise ratio (determined by the number of averaged TV frames). Obviously, the precision is restricted by geometric distortion mainly caused by the TV camera. For this reason, we are replacing the Gatan 622 TV camera with a modern high-grade CCD-based camera system. Such a system not only has negligible geometric distortion, but also high dynamic range (>10,000) and high resolution (1024x1024 pixels). The geometric distortion of the projector lenses can be measured, and corrected through re-sampling of the digitized image.

scholarly journals Chained graphs and some applications

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Anna Concas ◽  
Lothar Reichel ◽  
Giuseppe Rodriguez ◽  
Yunzi Zhang
Keyword(s):  
Information Transmission ◽  
City Planning ◽  
Structural Information ◽  
Closeness Centrality ◽  
Planning Algorithms ◽  
Definition Of

AbstractThis paper introduces the notions of chained and semi-chained graphs. The chain of a graph, when existent, refines the notion of bipartivity and conveys important structural information. Also the notion of a center vertex $$v_c$$ v c is introduced. It is a vertex, whose sum of p powers of distances to all other vertices in the graph is minimal, where the distance between a pair of vertices $$\{v_c,v\}$$ { v c , v } is measured by the minimal number of edges that have to be traversed to go from $$v_c$$ v c to v. This concept extends the definition of closeness centrality. Applications in which the center node is important include information transmission and city planning. Algorithms for the identification of approximate central nodes are provided and computed examples are presented.

scholarly journals Review of Studies on Older Drivers’ Behavior and Stress—Methods, Results, and Outlook

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3503
Author(s):  
Yanning Zhao ◽  
Toshiyuki Yamamoto
Keyword(s):  
Age Groups ◽  
Older Drivers ◽  
Driving Simulators ◽  
Driving Experience ◽  
Older Driver ◽  
Vehicle Data ◽  
Vehicle Systems ◽  
Questionnaire Surveys ◽  
Definition Of ◽  
Short Time

This paper presents a review on relevant studies and reports related to older drivers’ behavior and stress. Questionnaires, simulators, and on-road/in-vehicle systems are used to collect driving data in most studies. In addition, research either directly compares older drivers and the other drivers or considers participants according to various age groups. Nevertheless, the definition of ‘older driver’ varies not only across studies but also across different government reports. Although questionnaire surveys are widely used to affordably obtain massive data in a short time, they lack objectivity. In contrast, biomedical information can increase the reliability of a driving stress assessment when collected in environments such as driving simulators and on-road experiments. Various studies determined that driving behavior and stress remain stable regardless of age, whereas others reported degradation of driving abilities and increased driving stress among older drivers. Instead of age, many researchers recommended considering other influencing factors, such as gender, living area, and driving experience. To mitigate bias in findings, this literature review suggests a hybrid method by applying surveys and collecting on-road/in-vehicle data.

scholarly journals Zur exakten Behandlung von kollektiven Rotationen Teil A: Theorie / On the Exact Treatment of Collective Rotations Part A: Theory

1973 ◽  
Vol 28 (2) ◽  
pp. 206-215
Author(s):  
Hanns Ruder
Keyword(s):  
Coordinate System ◽  
Perturbation Expansion ◽  
Rotational Energy ◽  
The Body ◽  
System A ◽  
N Body Problem ◽  
Definition Of ◽  
Fixed System ◽  
Body Fixed Coordinate System ◽  
Groundstate Energy

Basic in the treatment of collective rotations is the definition of a body-fixed coordinate system. A kinematical method is derived to obtain the Hamiltonian of a n-body problem for a given definition of the body-fixed system. From this exact Hamiltonian, a consequent perturbation expansion in terms of the total angular momentum leads to two exact expressions: one for the collective rotational energy which has to be added to the groundstate energy in this order of perturbation and a second one for the effective inertia tensor in the groundstate. The discussion of these results leads to two criteria how to define the best body-fixed coordinate system, namely a differential equation and a variational principle. The equivalence of both is shown.

XV.—The Placoderm Fish Rhachiosteus pterygiatus Gross and its Relationships

1966 ◽  
Vol 66 (15) ◽  
pp. 377-392 ◽  
Author(s):  
Roger S. Miles
Keyword(s):  
Sensory System ◽  
System A ◽  
The Family ◽  
Definition Of

SynopsisThe holotype and only known specimen of Rhachiosteus pterygiatus Gross is partially redescribed and new restorations are given. Attention is drawn to important points in its osteology and the possible development of a cutaneous sensory system. A definition of the family Rhachiosteidsæ Stensiö is given. This family differs from all other described groups of euarthrodires in the lack of posterior lateral and posterior dorsolateral flank plates. Rhachiosteus is a pachyosteomorph brachythoracid, as defined in the text, and may be fairly closely related in some way to the (coccosteomorph) family Coccosteidsæ. There is no indication that it is closely related to any other known pachyosteomorph, or to other groups of arthrodires, such as the Rhenanida and Ptyctodontida, in which there are no posterior flank plates.

scholarly journals Implementation and application of E-technologies in enterprise environment

2007 ◽  
Vol 55 (3) ◽  
pp. 67-74
Author(s):  
Roman Malo
Keyword(s):  
Short Time Period ◽  
Logical Model ◽  
System A ◽  
Theoretical System ◽  
Time Period ◽  
Business Area ◽  
Basic Concepts ◽  
Short Time ◽  
Base Platform

Nowadays, a problem of an e- technologies’ implementation represents one of the most important questions that are being solved within various subjects from business area. With respect of massive implementation of activities as e- commerce, e- payments and others the e- technologies’ implementation is the progressive way of these subjects’ expansion. However, due to relatively short time period in which enterprise subjects have solved there is a set of vague aspects going together with this problem. The paper analyses the area of e- technologies and defines relations between basic concepts. Following this theoretical system a few hypothesis are constructed and used as a base platform for a determination of the logical model for implementation of e- technologies in enterprise environment.

scholarly journals Bank Stability Measures in Dual Banking System: A Critical Review

2019 ◽  
Vol 5 (2) ◽  
pp. 59
Author(s):  
Norzitah Abdul Karim ◽  
Amirul Afiff Muhamat ◽  
Azreen Roslan ◽  
Sharifah Faigah Syed Alwi ◽  
Mohamad Nizam Jaafar
Keyword(s):  
Global Financial Crisis ◽  
Financial Institution ◽  
Banking System ◽  
Banking Supervision ◽  
Basel Committee ◽  
System A ◽  
Overall Stability ◽  
Regulatory Bodies ◽  
Banking Stability ◽  
Definition Of

The 2007-2009 Global Financial Crisis showed that despite reported as ‘healthy’ financial institution prior to crisis had indeed suffered many problems including liquidity during the crisis. Thus, there is confusion on the healthy financial institutions, leading to loss of confidence on the overall stability of the banking system. Thus, there is an urgent need to review the current measures of financial as well as banking stability. This paper aims to look at the definition of ‘stability’ used in the academic researches and by different regulatory bodies, like International Monetary Fund, Basel Committee for Banking Supervision (BCBS) and central banks in selected countries with dual banking systems. It is then, critically review indicators used as measures of financial as well as banking stability. This review is hope to identify areas of strengths as well as weaknesses of the current measures of stability and serves as foundation for further research in future.

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