scholarly journals Dynamic, state-dependent thresholds for the perception of single-element apparent motion: Bistability from local cooperativity

1997 ◽  
Vol 59 (7) ◽  
pp. 1077-1088 ◽  
Author(s):  
Howard S. Hock ◽  
Kris Kogan ◽  
Jessica K. Espinoza
2011 ◽  
Vol 178 (6) ◽  
pp. 774-786 ◽  
Author(s):  
Who-Seung Lee ◽  
Neil B. Metcalfe ◽  
Pat Monaghan ◽  
Marc Mangel

Oecologia ◽  
2009 ◽  
Vol 160 (2) ◽  
pp. 399-410 ◽  
Author(s):  
A. D. Higginson ◽  
G. D. Ruxton

Author(s):  
Jason G. Romine ◽  
Joseph R. Benjamin ◽  
Russell W. Perry ◽  
Lynne Casal ◽  
Patrick J. Connolly ◽  
...  

2004 ◽  
Vol 42 (21) ◽  
pp. 4547-4562 ◽  
Author(s):  
J. C. Chen * ◽  
C.-W. Chen ◽  
C.-Y. Tai ◽  
J. C. Tyan

Author(s):  
Dennis Maher ◽  
David Joy ◽  
Peggy Mochel

A variety of standard specimens is needed in order to systematically investigate the instrumentation, specimen, data reduction and quantitation variables in electron energy-loss spectroscopy (EELS). Pure single element specimens (e.g. various forms of carbon) have received considerable attention to date but certain elements of interest cannot be prepared directly as thin films. Since studies of the first and second row elements in two- or multicomponent systems will be of considerable importance in microanalysis using EELS, there is a need for convenient standards containing these species. For many investigations a standard should contain the desired element, or elements, homogeneously dispersed through a suitable matrix and at an accurately known concentration. These conditions may be met by the technique of implantation.Silicon was chosen as the host lattice since its principal ionization energies, EL23 = 98 eV and Ek = 1843 eV, are well removed from the K-edges of most elements of major interest such as boron (Ek = 188 eV), carbon (Ek = 283 eV), nitrogen (Ek = 400 eV) and oxygen (Ek = 532 eV).


Author(s):  
Burton B. Silver

Sectioned tissue rarely indicates evidence of what is probably a highly dynamic state of activity in mitochondria which have been reported to undergo a variety of movements such as streaming, divisions and coalescence. Recently, mitochondria from the rat anterior pituitary have been fixed in a variety of configurations which suggest that conformational changes were occurring at the moment of fixation. Pinocytotic-like vacuoles which may be taking in or expelling materials from the surrounding cell medium, appear to be forming in some of the mitochondria. In some cases, pores extend into the matrix of the mitochondria. In other forms, the remains of what seems to be pinched off vacuoles are evident in the mitochondrial interior. Dense materials, resembling secretory droplets, appear at the junction of the pores and the cytoplasm. The droplets are similar to the secretory materials commonly identified in electron micrographs of the anterior pituitary.


Sign in / Sign up

Export Citation Format

Share Document