scholarly journals High Degree Vertices and Eigenvalues in the Preferential Attachment Graph

2003 ◽  
pp. 264-274 ◽  
Author(s):  
Abraham Flaxman ◽  
Alan Frieze ◽  
Trevor Fenner
Keyword(s):  
Preferential Attachment ◽  
High Degree

scholarly journals Vertices of high degree in the preferential attachment tree

2012 ◽  
Vol 17 (0) ◽  
Author(s):  
Graham Brightwell ◽  
Malwina Luczak
Keyword(s):  
Preferential Attachment ◽  
High Degree

scholarly journals High Degree Vertices and Eigenvalues in the Preferential Attachment Graph

2005 ◽  
Vol 2 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Abraham Flaxman ◽  
Alan Frieze ◽  
Trevor Fenner
Keyword(s):  
Preferential Attachment ◽  
High Degree

Supple networks: Preferential attachment by diversity in nascent social graphs

2014 ◽  
Vol 2 (3) ◽  
pp. 303-325 ◽  
Author(s):  
JAMESON K. M. WATTS ◽  
KENNETH W. KOPUT
Keyword(s):  
Social Networks ◽  
Network Formation ◽  
Preferential Attachment ◽  
Physical Review ◽  
Weak Ties ◽  
It Industry ◽  
Gender Stratification ◽  
Social Graphs ◽  
High Degree ◽  
Administrative Science

AbstractA preference for diversity has been identified as an important predictor of tie formation in certain networks, both social and organizational, that also exhibit a high degree of suppleness–the ability to retain their general form and character under stress (Durkheim, 1893/1997. The division of labor in society; Powell et al., 1996. Administrative Science Quarterly 116–145; Powell et al., 2005. American Journal of Sociology, 110(4), 1132–1205; Koput & Gutek, 2010. Gender stratification in the IT industry: Sex, status and social capital. Edward Elgar Publishing). Extant models of preferential attachment, based on popularity, similarity, and cohesion, meanwhile, produce exceedingly brittle networks (Albert et al., 2000. Nature, 406(6794), 378–382; Callaway et al., 2000. Physical Review Letters, 85(25), 5468–5471; Holme et al., 2002. Physical Review E, 65(2), 026107; Shore et al., 2013 Social Networks, 35(1), 116–123). A model of preferential attachment based on diversity is introduced and simulated, demonstrating that a preference for diversity can create a structure characterized by suppleness. This occurs because a preference for diversity promotes overlapping and redundant weak ties during the early stages of network formation.

Tissue section lifting for electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 86-87
Author(s):  
Adrian F. van Dellen
Keyword(s):  
Infectious Disease ◽  
Electron Microscopy ◽  
Tissue Culture ◽  
Organ System ◽  
Surrounding Tissue ◽  
Paraffin Sections ◽  
Surface Areas ◽  
Specific Determination ◽  
High Degree ◽  
Accuracy And Repeatability

The morphologic pathologist may require information on the ultrastructure of a non-specific lesion seen under the light microscope before he can make a specific determination. Such lesions, when caused by infectious disease agents, may be sparsely distributed in any organ system. Tissue culture systems, too, may only have widely dispersed foci suitable for ultrastructural study. In these situations, when only a few, small foci in large tissue areas are useful for electron microscopy, it is advantageous to employ a methodology which rapidly selects a single tissue focus that is expected to yield beneficial ultrastructural data from amongst the surrounding tissue. This is in essence what "LIFTING" accomplishes. We have developed LIFTING to a high degree of accuracy and repeatability utilizing the Microlift (Fig 1), and have successfully applied it to tissue culture monolayers, histologic paraffin sections, and tissue blocks with large surface areas that had been initially fixed for either light or electron microscopy.

Electron Microscopy in Molecular Biology

1967 ◽  
Vol 25 ◽  
pp. 2-3
Author(s):  
Cecil E. Hall
Keyword(s):  
Electron Microscopy ◽  
Molecular Biology ◽  
Noise Level ◽  
Molecular Structures ◽  
Material Structure ◽  
The Arts ◽  
Shadow Casting ◽  
Electron Image ◽  
High Degree ◽  
Very High

The visualization of organic macromolecules such as proteins, nucleic acids, viruses and virus components has reached its high degree of effectiveness owing to refinements and reliability of instruments and to the invention of methods for enhancing the structure of these materials within the electron image. The latter techniques have been most important because what can be seen depends upon the molecular and atomic character of the object as modified which is rarely evident in the pristine material. Structure may thus be displayed by the arts of positive and negative staining, shadow casting, replication and other techniques. Enhancement of contrast, which delineates bounds of isolated macromolecules has been effected progressively over the years as illustrated in Figs. 1, 2, 3 and 4 by these methods. We now look to the future wondering what other visions are waiting to be seen. The instrument designers will need to exact from the arts of fabrication the performance that theory has prescribed as well as methods for phase and interference contrast with explorations of the potentialities of very high and very low voltages. Chemistry must play an increasingly important part in future progress by providing specific stain molecules of high visibility, substrates of vanishing “noise” level and means for preservation of molecular structures that usually exist in a solvated condition.

A High Angle, Double Tilting Cold Stage for the AEI EM7

1974 ◽  
Vol 32 ◽  
pp. 450-451
Author(s):  
P.R. Swann ◽  
A.E. Lloyd
Keyword(s):  
Habit Plane ◽  
Temperature Control ◽  
Tilt Angle ◽  
Cooling System ◽  
Thermal Drift ◽  
High Angle ◽  
Cold Stage ◽  
High Degree ◽  
Better Than

Figure 1 shows the design of a specimen stage used for the in situ observation of phase transformations in the temperature range between ambient and −160°C. The design has the following features a high degree of specimen stability during tilting linear tilt actuation about two orthogonal axes for accurate control of tilt angle read-out high angle tilt range for stereo work and habit plane determination simple, robust construction temperature control of better than ±0.5°C minimum thermal drift and transmission of vibration from the cooling system.

New Aspects in the Design of Electron Optical Magnification Systems

1972 ◽  
Vol 30 ◽  
pp. 606-607
Author(s):  
Willem H.J. Andersen
Keyword(s):  
Electron Microscope ◽  
Imaging System ◽  
Chromatic Aberration ◽  
Research Tool ◽  
Energy Losses ◽  
Objective Lens ◽  
Theoretical Limit ◽  
Optical Magnification ◽  
Chromatic Aberrations ◽  
High Degree

Electron microscope design, and particularly the design of the imaging system, has reached a high degree of perfection. Present objective lenses perform up to their theoretical limit, while the whole imaging system, consisting of three or four lenses, provides very wide ranges of magnification and diffraction camera length with virtually no distortion of the image. Evolution of the electron microscope in to a routine research tool in which objects of steadily increasing thickness are investigated, has made it necessary for the designer to pay special attention to the chromatic aberrations of the magnification system (as distinct from the chromatic aberration of the objective lens). These chromatic aberrations cause edge un-sharpness of the image due to electrons which have suffered energy losses in the object.There exist two kinds of chromatic aberration of the magnification system; the chromatic change of magnification, characterized by the coefficient Cm, and the chromatic change of rotation given by Cp.

Cytoplasmic Organization in the Receptor Cells of the Crista Ampullaris

1972 ◽  
Vol 30 ◽  
pp. 60-61 ◽  
Author(s):  
Robert F. Dunn
Keyword(s):  
Fine Particles ◽  
Apical Cell ◽  
Apical Region ◽  
Receptor Cells ◽  
Cuticular Plate ◽  
Morphological Organization ◽  
Crista Ampullaris ◽  
Cytoplasmic Organization ◽  
High Degree ◽  
General Appearance

Receptor cells of the cristae in the vestibular labyrinth of the bullfrog, Rana catesbiana, show a high degree of morphological organization. Four specialized regions may be distinguished: the apical region, the supranuclear region, the paranuclear region, and the basilar region.The apical region includes a single kinocilium, approximately 40 stereocilia, and many small microvilli all projecting from the apical cell surface into the lumen of the ampulla. A cuticular plate, located at the base of the stereocilia, contains filamentous attachments of the stereocilia, and has the general appearance of a homogeneous aggregation of fine particles (Fig. 1). An accumulation of mitochondria is located within the cytoplasm basal to the cuticular plate.

Computer Reconstruction of the Cellular Architecture of the Daphnia Magna Optic Ganglion

1975 ◽  
Vol 33 ◽  
pp. 284-285
Author(s):  
E. R. Macagno ◽  
C. Levinthal
Keyword(s):  
Daphnia Magna ◽  
Genetic Background ◽  
Compound Eye ◽  
Synaptic Connectivity ◽  
Serial Sections ◽  
Cross Sectional ◽  
Small Crustacean ◽  
Optic Ganglion ◽  
Structural Invariance ◽  
High Degree

The optic ganglion of Daphnia Magna, a small crustacean that reproduces parthenogenetically contains about three hundred neurons: 110 neurons in the Lamina or anterior region and about 190 neurons in the Medulla or posterior region. The ganglion lies in the midplane of the organism and shows a high degree of left-right symmetry in its structures. The Lamina neurons form the first projection of the visual output from 176 retinula cells in the compound eye. In order to answer questions about structural invariance under constant genetic background, we have begun to reconstruct in detail the morphology and synaptic connectivity of various neurons in this ganglion from electron micrographs of serial sections (1). The ganglion is sectioned in a dorso-ventra1 direction so as to minimize the cross-sectional area photographed in each section. This area is about 60 μm x 120 μm, and hence most of the ganglion fit in a single 70 mm micrograph at the lowest magnification (685x) available on our Zeiss EM9-S.

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