Mobility, Orientation, and Navigation: Conceptual and Theoretical Considerations

1976 ◽  
Vol 70 (9) ◽  
pp. 385-391
Author(s):  
George Psathas
Keyword(s):  
Detailed Knowledge ◽  
Directed Movement ◽  
Moving Points ◽  
Theoretical Considerations ◽  
Complex Activities ◽  
Intended Destination ◽  
Person Orientation

Analyzes mobility, orientation, and navigation and describes the complex activities and detailed knowledge required by each. Mobility involves movement of an embodied person; orientation involves knowing where one is, in relation to fixed or moving points; navigation is directed movement with an intended destination and requires knowledge of directions and locations.

Analyzing reactions of single mechanoenzyme molecules by light microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 426-427
Author(s):  
Jeff Gelles
Keyword(s):  
Image Processing ◽  
Reaction Mechanisms ◽  
Transient State ◽  
Nanometer Scale ◽  
Reaction Intermediates ◽  
Enzyme Molecule ◽  
Directed Movement ◽  
Enzyme Molecules ◽  
Individual Enzyme ◽  
Single Reaction

Mechanoenzymes are enzymes which use a chemical reaction to power directed movement along biological polymer. Such enzymes include the cytoskeletal motors (e.g., myosins, dyneins, and kinesins) as well as nucleic acid polymerases and helicases. A single catalytic turnover of a mechanoenzyme moves the enzyme molecule along the polymer a distance on the order of 10−9 m We have developed light microscope and digital image processing methods to detect and measure nanometer-scale motions driven by single mechanoenzyme molecules. These techniques enable one to monitor the occurrence of single reaction steps and to measure the lifetimes of reaction intermediates in individual enzyme molecules. This information can be used to elucidate reaction mechanisms and determine microscopic rate constants. Such an approach circumvents difficulties encountered in the use of traditional transient-state kinetics techniques to examine mechanoenzyme reaction mechanisms.

An atomic-resolution microscope study of Al contracts on GaAs

1986 ◽  
Vol 44 ◽  
pp. 726-727
Author(s):  
Z. Liliental-Weber ◽  
C. Nelson ◽  
R. Ludeke ◽  
R. Gronsky ◽  
J. Washburn
Keyword(s):  
High Speed ◽  
Schottky Contacts ◽  
Detailed Knowledge ◽  
The Past ◽  
Semiconductor Interfaces ◽  
Deposited Metal ◽  
Microwave Applications ◽  
Free Interfaces ◽  
Potential Use

The properties of metal/semiconductor interfaces have received considerable attention over the past few years, and the Al/GaAs system is of special interest because of its potential use in high-speed logic integrated optics, and microwave applications. For such materials a detailed knowledge of the geometric and electronic structure of the interface is fundamental to an understanding of the electrical properties of the contact. It is well known that the properties of Schottky contacts are established within a few atomic layers of the deposited metal. Therefore surface contamination can play a significant role. A method for fabricating contamination-free interfaces is absolutely necessary for reproducible properties, and molecularbeam epitaxy (MBE) offers such advantages for in-situ metal deposition under UHV conditions

High Resolution Transmission Electron Microscopy of an automobile catalytic converter

1990 ◽  
Vol 48 (4) ◽  
pp. 242-243
Author(s):  
Jan-Olle Malm ◽  
Jan-Olov Bovin
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Catalytic Converter ◽  
Active Material ◽  
Image Intensifier ◽  
High Resolution Electron Microscopy ◽  
Detailed Knowledge ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Atomic Surface

Understanding of catalytic processes requires detailed knowledge of the catalyst. As heterogeneous catalysis is a surface phenomena the understanding of the atomic surface structure of both the active material and the support material is of utmost importance. This work is a high resolution electron microscopy (HREM) study of different phases found in a used automobile catalytic converter.The high resolution micrographs were obtained with a JEM-4000EX working with a structural resolution better than 0.17 nm and equipped with a Gatan 622 TV-camera with an image intensifier. Some work (e.g. EDS-analysis and diffraction) was done with a JEM-2000FX equipped with a Link AN10000 EDX spectrometer. The catalytic converter in this study has been used under normal driving conditions for several years and has also been poisoned by using leaded fuel. To prepare the sample, parts of the monolith were crushed, dispersed in methanol and a drop of the dispersion was placed on the holey carbon grid.

Mechanisms of ethylene biosynthesis and response in plants

2015 ◽  
Vol 58 ◽  
pp. 61-70 ◽  
Author(s):  
Paul B. Larsen
Keyword(s):  
Plant Growth ◽  
Growth And Development ◽  
Ethylene Biosynthesis ◽  
Unsaturated Hydrocarbon ◽  
Flower Senescence ◽  
Detailed Knowledge ◽  
Plant Growth And Development ◽  
Step Process ◽  
Ethylene Response ◽  
Ethylene Signalling

Ethylene is the simplest unsaturated hydrocarbon, yet it has profound effects on plant growth and development, including many agriculturally important phenomena. Analysis of the mechanisms underlying ethylene biosynthesis and signalling have resulted in the elucidation of multistep mechanisms which at first glance appear simple, but in fact represent several levels of control to tightly regulate the level of production and response. Ethylene biosynthesis represents a two-step process that is regulated at both the transcriptional and post-translational levels, thus enabling plants to control the amount of ethylene produced with regard to promotion of responses such as climacteric flower senescence and fruit ripening. Ethylene production subsequently results in activation of the ethylene response, as ethylene accumulation will trigger the ethylene signalling pathway to activate ethylene-dependent transcription for promotion of the response and for resetting the pathway. A more detailed knowledge of the mechanisms underlying biosynthesis and the ethylene response will ultimately enable new approaches to be developed for control of the initiation and progression of ethylene-dependent developmental processes, many of which are of horticultural significance.

Apportionment of Impairment from Meniscal Tears and Knee Arthritis

2013 ◽  
Vol 18 (5) ◽  
pp. 1-10 ◽  
Author(s):  
Charles N. Brooks ◽  
James B. Talmage
Keyword(s):  
Medial Meniscus ◽  
Degenerative Joint Disease ◽  
Joint Disease ◽  
Detailed Knowledge ◽  
Meniscal Tears ◽  
Knee Arthritis ◽  
Degenerative Arthritis ◽  
Study Results ◽  
Physical Findings ◽  
Causation Analysis

Abstract Meniscal tears and osteoarthritis (osteoarthrosis, degenerative arthritis, or degenerative joint disease) are two of the most common conditions involving the knee. This article includes definitions of apportionment and causes; presents a case report of initial and recurrent tears of the medial meniscus plus osteoarthritis (OA) in the medial compartment of the knee; and addresses questions regarding apportionment. The authors, experienced impairment raters who are knowledgeable regarding the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), show that, when instructions on impairment rating are incomplete, unclear, or inconsistent, interrater reliability diminishes (different physicians may derive different impairment estimates). Accurate apportionment of impairment is a demanding task that requires detailed knowledge of causation for the conditions in question; the mechanisms of injury or extent of exposures; prior and current symptoms, functional status, physical findings, and clinical study results; and use of the appropriate edition of the AMA Guides. Sometimes the available data are incomplete, requiring the rating physician to make assumptions. However, if those assumptions are reasonable and consistent with the medical literature and facts of the case, if the causation analysis is plausible, and if the examiner follows impairment rating instructions in the AMA Guides (or at least uses a rational and hence defensible method when instructions are suboptimal), the resulting apportionment should be credible.

The Biological Clock and Sleep in the Elderly

2006 ◽  
Vol 19 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Myriam Juda ◽  
Mirjam Münch ◽  
Anna Wirz-Justice ◽  
Martha Merrow ◽  
Till Roenneberg
Keyword(s):  
Circadian Rhythms ◽  
Biological Clock ◽  
The Elderly ◽  
Early Morning ◽  
Behavioral Changes ◽  
Older Age ◽  
Age Related ◽  
Theoretical Considerations ◽  
Sleep Difficulties ◽  
Circadian Biology

Abstract: Among many other changes, older age is characterized by advanced sleep-wake cycles, changes in the amplitude of various circadian rhythms, as well as reduced entrainment to zeitgebers. These features reveal themselves through early morning awakenings, sleep difficulties at night, and a re-emergence of daytime napping. This review summarizes the observations concerning the biological clock and sleep in the elderly and discusses the documented and theoretical considerations behind these age-related behavioral changes, especially with respect to circadian biology.

The Glissonian Approach of the Hilum

Swiss Surgery ◽  
1999 ◽  
Vol 5 (3) ◽  
pp. 143-146 ◽  
Author(s):  
Launois ◽  
Maddern ◽  
Tay
Keyword(s):  
Portal Vein ◽  
Hepatic Artery ◽  
Posterior Approach ◽  
Hepatic Duct ◽  
Rapid Evolution ◽  
Hepatic Tissue ◽  
Detailed Knowledge ◽  
Porta Hepatis ◽  
Liver Segment ◽  
Glissonian Approach

The detailed knowledge of the segmental anatomy of the liver has led to a rapid evolution in resectional surgery based on the intrahepatic distribution of the portal trinity (the hepatic artery, hepatic duct and portal vein). The classical intrafascial or extrahepatic approach is to isolate the appropriate branch of the portal vein, hepatic artery and the hepatic duct, outside the liver substance. Another method, the extrafascial approach, is to dissect the whole sheath of the pedicle directly after division of a substantial amount of the hepatic tissue to reach the pedicle, which is surrounded by a sheath, derived from Glisson's capsule. This Glissonian sheath encloses the portal trinity. In the transfissural or intrahepatic approach, these sheaths can be approached either anteriorly (after division of the main, right or umbilical fissure) or posteriorly from behind the porta hepatis. We describe the technique for approaching the Glissonian sheath and hence the hepatic pedicle structures and their branches by the intrahepatic posterior approach that allows early delineation of the liver segment without the need for ancillary techniques. In addition, the indications for the use of this technique in the technical and oncologic settings are also discussed.

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