scholarly journals An Overview of Computational MHD Jets and Their Comparisons with Recent High Resolution Radio Images

1990 ◽  
Vol 140 ◽  
pp. 403-412
Author(s):  
David A. Clarke
Keyword(s):  
High Resolution ◽  
Numerical Simulations ◽  
Stokes Parameters ◽  
Synchrotron Emission ◽  
Significant Progress ◽  
Astrophysical Jets ◽  
Axisymmetric Jet ◽  
Radio Jets ◽  
Made In

Significant progress has been made in comparing numerical simulations with radio images of astrophysical jets. One is no longer forced to compare density slices through an axisymmetric jet simulation with observed Stokes I images. With the advent of MHD codes and modern supercomputers, models can now be constrained by all four Stokes parameters. In this paper, recent efforts to simulate synchrotron emission images of extragalactic radio jets are reviewed.

scholarly journals Dark cloud observations: Problems and progress

1997 ◽  
Vol 178 ◽  
pp. 173-182
Author(s):  
Y. C. Minh
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Recent Progress ◽  
High Resolution Spectroscopy ◽  
Significant Progress ◽  
Dark Cloud ◽  
Dark Clouds ◽  
Number Of Species ◽  
Observing Techniques ◽  
Made In

Interstellar dark clouds have provided a laboratory which has been successfully used to identify a number of species, perform high resolution spectroscopy, and characterize the processes in the interstellar medium. We have successfully solved a number of problems and achieved significant progress through dark cloud observations. With the improvement of observing techniques and theories, however, we are now having new problems and are waiting for further progress. The dark clouds, because of their quietness and large column densities, still provide a very useful testing ground of many uncertain interstellar processes. Here we summarize some of the recent progress made in dark cloud observations and discuss related problems. We focus especially on the importance of nearby objects, possible signs of gas-grain interactions in dark clouds, and further sensitive observations.

Low-voltage SEM update

1986 ◽  
Vol 44 ◽  
pp. 654-657
Author(s):  
J.B. Pawley ◽  
W.R. Scala
Keyword(s):  
High Resolution ◽  
Low Voltage ◽  
Low Energy ◽  
Special Issue ◽  
Significant Progress ◽  
Beam Voltage ◽  
Signal Collection ◽  
Upper Stage ◽  
Micro Lens ◽  
Made In

The advantages of operating an SEM at low beam voltage (Vo) are now widely recognized and significant progress has been made in overcoming the practical limitations to high resolution operation with Vo = 1-2 kV. A Symposium on Low Voltage SEM (LVSEM) was held at the 1984 EMSA meeting and several of the papers presented there were later collected for a special issue of the Journal of Microscopy. The purpose of this contribution is to outline three developments in instrumentation for LVSEM that have recently appeared. These include: 1) The new pole-pieces on the upper stage of the ISI DS-130c which permit it to produce very low aberration coefficients with low energy beams. 2) The replacement of the final lens of the Hitachi S-800, field emission SEM with an immersion lens to create the new S-900; 3) The development of the micro-lens for mounting in the chamber on a conventional’ SEM to produce both low aberration coefficients and a favorable geometry for signal collection.

scholarly journals Young radio jets breaking free: molecular and HI outflows in their centers

2018 ◽  
Vol 14 (S342) ◽  
pp. 85-89
Author(s):  
Raffaella Morganti ◽  
Tom Oosterloo ◽  
Robert Schulz ◽  
Clive Tadhunter ◽  
J. B. Raymond Oonk
Keyword(s):  
High Resolution ◽  
Numerical Simulations ◽  
Plasma Jet ◽  
Molecular Gas ◽  
First Order ◽  
Physical Conditions ◽  
Radio Jets ◽  
Central Regions

AbstractOur view of the central regions of AGN has been enriched by the discovery of fast and massive outflows of H I and molecular gas. Here we present a brief summary of results obtained for young (and restarted) radio AGN. We find that H I outflows tend to be particularly common in this group of objects. This supports the idea that the jet, expanding in a clumpy medium, plays a major role in driving these outflows. The clumpiness of the medium is confirmed by VLBI and ALMA observations. The H I observations reveal that, at least part of the gas, is distributed in clouds with sizes up to a few tens of pc and mass ~104Mȯ. A change of the conditions in the outflow, with an increasing fraction of diffuse components, as the radio jets grow, is suggested by the high resolution H I observations. The molecular gas completes the picture, showing that the radio plasma jet can couple well with the ISM, strongly affecting the kinematics, but also the physical conditions of the molecular gas. This is confirmed by numerical simulations reproducing, to first order, the kinematics of the gas.

The parsec-scale structure of jet-driven H I out ows in radio galaxies

2018 ◽  
Vol 14 (A30) ◽  
pp. 74-77
Author(s):  
Raffaella Morganti ◽  
Robert Schulz ◽  
Kristina Nyland ◽  
Zsolt Paragi ◽  
Tom Oosterloo ◽  
...  
Keyword(s):  
High Resolution ◽  
Low Power ◽  
Numerical Simulations ◽  
Feedback Loop ◽  
Radio Galaxies ◽  
Scale Structure ◽  
Multiple Roles ◽  
Radio Jets ◽  
Vlbi Observations

AbstractRadio jets can play multiple roles in the feedback loop by regulating the accretion of the gas, by enhancing gas turbulence, and by driving gas outflows. Numerical simulations are beginning to make detailed predictions about these processes. Using high resolution VLBI observations we test these predictions by studying how radio jets of different power and in different phases of evolution affect the properties and kinematics of the surrounding H I gas. Consistent with predictions, we find that young (or recently restarted) radio jets have stronger impact as shown by the presence of H I outflows. The outflowing medium is clumpy with clouds of with sizes up to a few tens of pc and mass ∼ 104Mȯ) already in the region close to the nucleus (< 100 pc), making the jet interact strongly and shock the surrounding gas. We present a case of a low-power jet where, as suggested by the simulations, the injection of energy may produce an increase in the turbulence of the medium instead of an outflow.

scholarly journals Toward Quantitative Defect Analysis Using HREM

1996 ◽  
Vol 4 (6) ◽  
pp. 8-11
Author(s):  
David J. Smith
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Defect Analysis ◽  
Significant Progress ◽  
Detailed Characterization ◽  
Resolution Electron ◽  
High Resolution Images ◽  
High Resolution Electron Microscope ◽  
20 Nm ◽  
Made In

The electron microscope has evolved to the level where it is now straightforward to record high-resolution images from thin samples (t~ to 20 nm) that are directly interpretable in terms of atomic arrangements. Whilst recorded images necessarily represent two-dimensional projections of the structure, many defects such as dislocations and interfaces may be linear or planar in nature and this might be expected to be amenable to detailed characterization. In this review, we briefly consider the recent significant progress that has been made in quantitative defect analysis using the high-resolution electron microscope and then discuss some drawbacks to the technique as well as potential scope for further improvements.

Toward quantitative defect analysis using HREM

1994 ◽  
Vol 52 ◽  
pp. 714-715
Author(s):  
David J. Smith
Keyword(s):  
Electron Microscope ◽  
Unit Cell ◽  
Defect Analysis ◽  
Significant Progress ◽  
Detailed Characterization ◽  
Small Unit ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
Large Unit Cell ◽  
Made In

The electron microscope has evolved to the level where it is now straightforward to record highresolution images from thin samples (t∼10 to 20nm) that are directly interpretable in terms of atomic arrangements. Whilst recorded images necessarily represent two-dimensional projections of the structure, many defects such as dislocations and interfaces may be linear or planar in nature and thus might be expected to be amenable to detailed characterization. In this review, we briefly consider the recent significant progress that has been made in quantitative defect analysis using the high-resolution electron microscope and then discuss some drawbacks to the technique as well as potential scope for further improvements. Surveys of defect modelling for some small-unit-cell materials and interfaces have recently been published, and reference should be made to other papers in this symposium for further examples.The technique of structure imaging originated in the early '70s with observations of large-unit-cell block oxides.

Automatic Registering and Stitching of TEM/STEM Image Mosaics

2013 ◽  
Author(s):  
Chung-Ching Lin ◽  
Franco Stellari ◽  
Lynne Gignac ◽  
Peilin Song ◽  
John Bruley
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Vlsi Circuit ◽  
Significant Progress ◽  
Research Areas ◽  
Automated Method ◽  
Transmission Electron ◽  
Stem Image ◽  
High Resolution Images ◽  
Global Optimal

Abstract Transmission Electron Microscopy (TEM) and scanning TEM (STEM) is widely used to acquire ultra high resolution images in different research areas. For some applications, a single TEM/STEM image does not provide enough information for analysis. One example in VLSI circuit failure analysis is the tracking of long interconnection. The capability of creating a large map of high resolution images may enable significant progress in some tasks. However, stitching TEM/STEM images in semiconductor applications is difficult and existing tools are unable to provide usable stitching results for analysis. In this paper, a novel fully automated method for stitching TEM/STEM image mosaics is proposed. The proposed method allows one to reach a global optimal configuration of each image tile so that both missing and false-positive correspondences can be tolerated. The experiment results presented in this paper show that the proposed method is robust and performs well in very challenging situations.

KERCH STRAIT IN KAMYSH-BURUN SPIT AREA: HIGH-RESOLUTION SEISMOACOUSTIC APPROACH

2018 ◽  
Author(s):  
В. Зинько ◽  
V. Zin'ko ◽  
А. Зверев ◽  
A. Zverev ◽  
М. Федин ◽  
...  
Keyword(s):  
High Resolution ◽  
Fracture Zone ◽  
Sedimentary Cover ◽  
Sedimentary Rocks ◽  
The West ◽  
Early Generation ◽  
The Third ◽  
Azov Sea ◽  
Kerch Strait ◽  
Made In

The seismoacoustical investigations was made in the western part of the Kerch strait (Azov sea) near Kamysh-Burun spit. The fracture zone with dislocated sedimentary rocks layers and buried erosional surface was revealed to the west of spit. Three seismofacial units was revealed to the east of spit. The first unit was modern sedimentary cover. The second ones has cross-bedding features and was, probably, the part of early generation of Kamysh-Burun spit, which lied to the east of its modern position. The lower border of the second unit is the erosional surface supposed of phanagorian age. The third unit is screened by acoustic shedows in large part.

Biomarkers for Early Detection of Colitis-associated Colorectal Cancer - Current Concepts, Future Trends

2020 ◽  
Vol 22 (1) ◽  
pp. 137-145
Author(s):  
Tomasz Mackiewicz ◽  
Aleksander Sowa ◽  
Jakub Fichna
Keyword(s):  
Colorectal Cancer ◽  
Early Detection ◽  
Cancer Development ◽  
Sporadic Colorectal Cancer ◽  
Future Trends ◽  
Significant Progress ◽  
Current Standard ◽  
Risk Of Cancer ◽  
Histological Testing ◽  
Made In

: Colitis-associated colorectal cancer (CAC) remains a critical complication of ulcerative colitis (UC) with mortality of approximately 15%, which makes early CAC diagnosis crucial. The current standard of surveillance, with repetitive colonoscopies and histological testing of biopsied mucosa samples is burdensome and expensive, and therefore less invasive methods and reliable biomarkers are needed. Significant progress has been made thanks to continuous extensive research in this field, however no clinically relevant biomarker has been established so far. This review of the current literature presents the genetic and molecular differences between CAC and sporadic colorectal cancer and covers progress made in the early detection of CAC carcinogenesis. It focuses on biomarkers under development, which can be easily tested in samples of body fluids or breath and, once made clinically available, will help to differentiate between progressors (UC patients who will develop dysplasia) from non-progressors and enable early intervention to decrease the risk of cancer development.

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