Nahum Gershon | The MITRE Corp. (original) (raw)

Papers by Nahum Gershon

Physica, May 1, 1973

Recently it has been shownl) that in molecular fluids composed of nonspherica molecules the trace... more Recently it has been shownl) that in molecular fluids composed of nonspherica molecules the traceless symmetric polarizability density, &, can couple to the hydrodynamic modes of the system, viz. the number density, nk, the linear momentum density, gk, the total energy density ek and to the internal angular momentum (spin) density, Sk, where the subscript k denotes the k component of a

Springer eBooks, 1974

In this work we present theories for low frequency depolarized light scattering from liquids. Exp... more In this work we present theories for low frequency depolarized light scattering from liquids. Expressions for the various line shapes are given which depend on the geometry of the experiments and on temperature. We show how details of the rotational, translational and vibrational molecular motion can be extracted from these experiments.

Chemischer Informationsdienst, Jul 20, 1971

ChemInform Abstract Die Intensitäten der scharfen (diffusen) Komponenten und des Untergrundes im ... more ChemInform Abstract Die Intensitäten der scharfen (diffusen) Komponenten und des Untergrundes im depolarisierten Streulicht einiger aromatischer Flüssigkeiten wie z.B. Chinolin, o-, m-, p-Nitro-toluol, Nitro-, Brom-, Chlorbenzol, Benzonitril, Anilin, Pyridin, Lacto-, Malonound Acrylnitril wurden in Abhängigkeit von der Temperatur gemessen. Der Anteil, den unkorrelierte Moleküle zur Intensität beitragen, wird als Funktion der Temperatur berechnet und mit den Messergebnissen verglichen. Daraus lässt sich schliessen, dass die diffuse Linie von der Orientierungsrelaxation einer ziemlich stabilen Konfiguration ("Quasimolekül") herrührt, wobei sich das Molekül mit seinen Nachbarn im Orientierungsgleichgewicht befindet.

Information Visualization, Dec 1, 2005

... Steve Roth: a memoriam. Source, Information Visualization archive Volume 4 , Issue 4 (October... more ... Steve Roth: a memoriam. Source, Information Visualization archive Volume 4 , Issue 4 (October 2005) table of contents. Pages: 290 - 291. Year of Publication: 2005. ISSN:1473-8716. Authors, Nahum Gershon, Visualization & Storytelling, The MITRE Corporation, McLean, VA. Jake ...

Physica, 1974

Abstract It is shown that, within the framework of the work of Weinberg and Oppenheim on fluids o... more Abstract It is shown that, within the framework of the work of Weinberg and Oppenheim on fluids of spherical molecules with vibrational degrees of freedom, a dispersion in the sound velocity occurs when the rate of vibration-translation exchange is comparable with the reciprocal of the Brillouin frequency. In addition the Brillouin width, in this case, has a more complicated k dependence than k 2 .

IEEE Computer Graphics and Applications, Jul 1, 1998

The proof of the pudding is in the eating."-An English proverb O ne of the major challenges of in... more The proof of the pudding is in the eating."-An English proverb O ne of the major challenges of information visualization is using it to solve realworld problems in diverse areas such as telecommunications, financial analysis, software engineering, command and control, and information systems. The real world is complicated. Data and information are often complex, massive, time dependent, of diverse types, and not always reliable. To make the situation even more complex, users come with all levels of capabilities, education, and tastes. All of these facts further complicate the visualization process. Unfortunately, academic interests rather than applicability to real-life situations tend to motivate a large part of the research and development in visualization. This creates a visualization "bag of tricks" according to our colleague Ken Boff. An alternative, more demanding-but necessaryapproach is to study the problem first and then look for appropriate solutions (for example, using information visualization, if appropriate). Those of us in the visualization community need to realize that in many realworld applications, visualization is just one component of a complex system rather than a stand-alone entity. We also need to understand the system and the user needs in order to create effective visualizations. The section on information visualization in this special issue presents examples of the potential usefulness of information visualization in real-life environments containing large amounts of complex data and information. From the wide range of issues concerning this practical area, we chose to focus mainly on one aspectscaling. This scaling issue-how to deal with massive amounts of complex data and information practicallyis very important. Methodologies for dealing with large amounts of data and information can be classified as follows: 1. Condensing. Condensing large amounts of information into a given display space. Consider the following: s Tile maps-assigning an information unit to each pixel (for software management 1 and long lists 2). s Hyperbolic representation of large hierarchies 3

Proceedings of the National Academy of Sciences of the United States of America, Mar 1, 1978

Biophysical Journal, Oct 1, 1985

Molecules diffusing on nonplanar membranes, which have different amounts of corrugation in differ... more Molecules diffusing on nonplanar membranes, which have different amounts of corrugation in different directions, may experience dissimilar diffusion coefficients in each direction. Smith et al. (1979, Proc. Natl. Acad. Sci. USA, 76:5641-5644) measured diffusion anisotropy on fibroblast cell membranes in which the ratio of the diffusion coefficients, in different directions, was 0.27. In the present work we calculate the effect of anisotropic corrugation on the rate of diffusion of molecules on membranes. We find that part of the anisotropy reported by Smith et al. (1979, Proc. Natl. Acad. Sci. USA, 76:5641-5644) can be explained by the membrane nonplanarity, and we present the way of calculating this geometric factor.

Experimental Cell Research, Aug 1, 1979

Electron micrographs obtained from platinum-carbon replicas of freeze-cleaved or freeze-dried cel... more Electron micrographs obtained from platinum-carbon replicas of freeze-cleaved or freeze-dried cells and exhibiting intramembranous or externally-disposed particles were analysed statistically for degree of non-random particle association. Analysis was based on use of an analogy to the radial distribution function, g(r), which provided the average density of neighbor particles around a particle in the micrograph at 30 8, increments from particle center. The ratio of average density of neighbors around a particle to overall particle density in the micrograph was then determined as a function of distance from particle center. For a random plot of 90 A particles, the computed ratio deviated from 1 by less than 10% for a distance up to 900 A from particle center. In a field of similarly-sized intramembranous particles within the freeze-cleaved surface membrane of a mouse fibroblast, there were indications of slight non-random particle associations at distances of 120-240 A and 300-330 8, from particle center, while a significant association of particles comprising an intercellular gap junction was obtained at 90-120 A. Virus-related molecuhu assemblies on the surfaces of fibroblasts infected with a temperature-sensitive mutant of murine luekemia virus and grown under conditions that did not permit virus assembly to occur were analysed similarly. Significant deviation from randomness was found at several distances from particle center, both on areas of membrane that were populated by large numbers of particles and on low-density areas.

Ki - Künstliche Intelligenz, Mar 21, 2012

is one of the earliest pioneers of object-oriented programming, personal computing, and graphical... more is one of the earliest pioneers of object-oriented programming, personal computing, and graphical user interfaces. His contributions have been recognized with: • the Charles Stark Draper Prize of the National Academy of Engineering 1 "for the vision, conception, and development of the first practical networked personal computers" • the Alan. M. Turing Award from the Association of Computing Machinery "for pioneering many of the ideas at the root of contemporary object-oriented programming languages, leading the team that developed Smalltalk, and for fundamental contributions to personal computing"

Chemical Physics Letters, Jun 1, 1977

The cowling ~nmtnetcr X between the tran&ttlorW and orren~ational motions rvhrch d~~~ri~iR~s the ... more The cowling ~nmtnetcr X between the tran&ttlorW and orren~ational motions rvhrch d~~~ri~iR~s the lincshapc~ of the VH depolarized light scattering from fluids of nonspher~~l rno~ecuIes 1s cakulatc~. Using the currclttton junctions w-pr~s-Sian, given by Gcrshon and Oppcnhclm, and a single phcnomcnolugical ar\umptlon yrclds the e~pcrrmcntatly graven depcndcnce of X un the shear wscosity.

Springer eBooks, 1996

Contents: Part One: Knowledge: The Driving Force in CAD Systems: Creative Design and its Cognitiv... more Contents: Part One: Knowledge: The Driving Force in CAD Systems: Creative Design and its Cognitive Components Information.- Artificial Intelligence in Knowledge Based Systems (KBS).- Modeling Tools for Knowledge Discovery.- Part Two: New Data Channels: Industrial Information Tools: Industrial Information Exchange: Step, Standards and CAD Design Needs.- Information Seeking Strategies: Selective Access to Current Information Online.- Information Resources: Intelligent Complex Databases.

In this paper we present the use of a priori knowledge in the registration of PET and MR brain im... more In this paper we present the use of a priori knowledge in the registration of PET and MR brain images and in the construction of a knowledge base of brain image data. The registration is achieved through the use of brain anatomical landmarks as fiduciary marks. The interhemispheric fissure, a surface landmark, is segmented automatically. Further segmentation could be used in building a knowledge base system. To ensure efficient use of the knowledge, a suitable organization for the image and associated data base is proposed. This type of approach could be used to construct an expert system for the correlation of structure and function of the brain and other anatomical components.

Chemical Physics Letters, Aug 1, 1974

A theory for non-equilibrium shear relaxation in liquids at low frequencies is presented. It is b... more A theory for non-equilibrium shear relaxation in liquids at low frequencies is presented. It is based on molecular considerations used in theories of low frequency depolarized light scattering. The results for the complex shear impedance contain terms in addition to those obtained by the phenomenologi cal relaxation theory.

IEEE Computer Graphics and Applications, Mar 1, 1996

Conclusion A fundamental aspect of information visualization nvolves the display of relationships... more Conclusion A fundamental aspect of information visualization nvolves the display of relationships among objects. Vode and link diagrams, although natural choices to lisplay this class of data, are easily overwhelmed with 00 much information, becoming cluttered and visual-y ...

The Journal of Membrane Biology, Jun 1, 1981

Chemischer Informationsdienst, Dec 28, 1971

Crosslinking of membrane surface receptors may lead to their segregation into patches and then in... more Crosslinking of membrane surface receptors may lead to their segregation into patches and then into a single large aggregate at one pole of the cell. This process is called capping. Here, a novel explanation of such a process is presented in which the membrane is viewed as a supersaturated solution of receptors in the lipid bilayer and the adjacent two aqueous layers. Without a crosslinking agent, a patch of receptors that is less than a certain size cannot stay in equilibrium with the solution and thus should dissolve. Patches greater than a certain size are stable and can, in principle, grow by the precipitation of the remaining dissolved receptors from the supersaturated solution. The task of the crosslinking molecules is to form such stable patches. These considerations are based on a qualitative thermodynamic calculation that takes into account the existence of a boundary tension in a patch (in analogy to the surface ten- sion of a droplet). Thermodynamically, these systems should cap spontaneously after the patches have reached a certain size. But, in practice, such a process can be very slow. A suspension of patches may stay practically stable. The ways in which a cell may abolish this metastable equilibrium and thus achieve capping are considered and possible effects of capping inhibi- tors are discussed.

Chemical Physics Letters, Mar 1, 1974

Abstract In this work it is shown that because of the different symmetry of the variables the tim... more Abstract In this work it is shown that because of the different symmetry of the variables the time dependence of the auto-correlation function of the time derivative of the anisotropic polarizability density can be different from that of the molecular angular momentum density auto-correlation function. Thus the information on this angular momentum correlation function that can be deduced from that of the time derivative of the anisotropic polarizability density can be limited.