Two-length-scale problem in critical scattering: Narrow-component line shape

1997 ◽  
Vol 56 (1) ◽  
pp. 166-169 ◽  
Author(s):  
M. Papoular ◽  
M. D. Núñez-Regueiro ◽  
M. Altarelli
2009 ◽  
Vol 5 (S266) ◽  
pp. 555-555
Author(s):  
Richard Wünsch ◽  
Jan Palouš ◽  
Guillermo Tenorio–Tagle ◽  
Sergiy Silich ◽  
Casiana Muñoz–Tuñón

AbstractSuper star clusters (SSCs) are young massive objects typically observed in starburst galaxies. They consist of millions of stars occupying volumes only several parsecs across. Recent infrared observations of SSCs reveal strong emission lines with moderately supersonic widths (FWHM ~ 50 – 100 km s−1). An additional, much broader and weaker line component is present in some cases. Using 2D and 3D hydrodynamic simulations, we study models of SSCs in the so-called bimodal regime, which occurs if the stellar density inside the cluster exceeds a certain limit. We confirm the existence of the bimodal solution predicted analytically and suggest an explanation for double-component line profiles: the narrow component is formed close to the cluster center by repressurizing shocks compressing the rarefied gas cooled down due to the thermal instability into dense cold clumps, while the broad component is created by the wind, which cools down at a certain distance from the cluster.


Author(s):  
M. Sarikaya ◽  
J. T. Staley ◽  
I. A. Aksay

Biomimetics is an area of research in which the analysis of structures and functions of natural materials provide a source of inspiration for design and processing concepts for novel synthetic materials. Through biomimetics, it may be possible to establish structural control on a continuous length scale, resulting in superior structures able to withstand the requirements placed upon advanced materials. It is well recognized that biological systems efficiently produce complex and hierarchical structures on the molecular, micrometer, and macro scales with unique properties, and with greater structural control than is possible with synthetic materials. The dynamism of these systems allows the collection and transport of constituents; the nucleation, configuration, and growth of new structures by self-assembly; and the repair and replacement of old and damaged components. These materials include all-organic components such as spider webs and insect cuticles (Fig. 1); inorganic-organic composites, such as seashells (Fig. 2) and bones; all-ceramic composites, such as sea urchin teeth, spines, and other skeletal units (Fig. 3); and inorganic ultrafine magnetic and semiconducting particles produced by bacteria and algae, respectively (Fig. 4).


Author(s):  
I-Fei Tsu ◽  
D.L. Kaiser ◽  
S.E. Babcock

A current theme in the study of the critical current density behavior of YBa2Cu3O7-δ (YBCO) grain boundaries is that their electromagnetic properties are heterogeneous on various length scales ranging from 10s of microns to ˜ 1 Å. Recently, combined electromagnetic and TEM studies on four flux-grown bicrystals have demonstrated a direct correlation between the length scale of the boundaries’ saw-tooth facet configurations and the apparent length scale of the electrical heterogeneity. In that work, enhanced critical current densities are observed at applied fields where the facet period is commensurate with the spacing of the Abrikosov flux vortices which must be pinned if higher critical current density values are recorded. To understand the microstructural origin of the flux pinning, the grain boundary topography and grain boundary dislocation (GBD) network structure of [001] tilt YBCO bicrystals were studied by TEM and HRTEM.


1998 ◽  
Vol 08 (PR8) ◽  
pp. Pr8-159-Pr8-166 ◽  
Author(s):  
S. Fouvry ◽  
Ph. Kapsa ◽  
F. Sidoroff ◽  
L. Vincent

TAPPI Journal ◽  
2010 ◽  
Vol 9 (10) ◽  
pp. 7-15
Author(s):  
HANNA KOIVULA ◽  
DOUGLAS BOUSFIELD ◽  
MARTTI TOIVAKKA

In the offset printing process, ink film splitting has an important impact on formation of ink filaments. The filament size and its distribution influence the leveling of ink and hence affect ink setting and the print quality. However, ink filaments are difficult to image due to their short lifetime and fine length scale. Due to this difficulty, limited work has been reported on the parameters that influence filament size and methods to characterize it. We imaged ink filament remains and quantified some of their characteristics by changing printing speed, ink amount, and fountain solution type. Printed samples were prepared using a laboratory printability tester with varying ink levels and operating settings. Rhodamine B dye was incorporated into fountain solutions to aid in the detection of the filaments. The prints were then imaged with a confocal laser scanning microscope (CLSM) and images were further analyzed for their surface topography. Modeling of the pressure pulses in the printing nip was included to better understand the mechanism of filament formation and the origin of filament length scale. Printing speed and ink amount changed the size distribution of the observed filament remains. There was no significant difference between fountain solutions with or without isopropyl alcohol on the observed patterns of the filament remains.


Author(s):  
Mary Smith ◽  
Thomas Blake ◽  
Robert Sams ◽  
Candice Renaud ◽  
Bastien Vispoel ◽  
...  

2002 ◽  
Vol 715 ◽  
Author(s):  
T. Su ◽  
Robin Plachy ◽  
P. C. Taylor ◽  
S. Stone ◽  
G. Ganguly ◽  
...  

AbstractWe study the H NMR line shapes of a sample of a-Si:H under several conditions: 1) as grown, 2) light-soaked for 600 hours, and 3) light-soaked followed by annealing at different temperatures. At T = 7 K, the NMR line shape of the sample after light soaking exhibits an additional doublet compared to that of the sample as-grown. This doublet is an indication of a closely separated hydrogen pair. The distance between the two hydrogen atoms is estimated to be about (2.3 ± 0.2) Å. The concentration of these hydrogen sites is estimated to be between 1017 and 1018 cm-3 consistent with ESR measurements of the defect density after light soaking. This doublet disappears after the sample is annealed at 200°C for 4 hours.


2003 ◽  
Vol 773 ◽  
Author(s):  
Xiefan Lin ◽  
Anthony S. W. Ham ◽  
Natalie A. Villani ◽  
Whye-Kei Lye ◽  
Qiyu Huang ◽  
...  

AbstractStudies of selective adhesion of biological molecules provide a path for understanding fundamental cellular properties. A useful technique is to use patterned substrates, where the pattern of interest has the same length scale as the molecular bonding sites of a cell, in the tens of nanometer range. We employ electrochemical methods to grow anodic alumina, which has a naturally ordered pore structure (interpore spacing of 40 to 400 nm) controlled by the anodization potential. We have also developed methods to selectively fill the alumina pores with materials with contrasting properties. Gold, for example, is electrochemically plated into the pores, and the excess material is removed by backsputter etching. The result is a patterned surface with closely separated islands of Au, surrounded by hydrophilic alumina. The pore spacing, which is determined by fabrication parameters, is hypothesized to have a direct effect on the spatial density of adhesion sites. By attaching adhesive molecules to the Au islands, we are able to observe and study cell rolling and adhesion phenomena. Through the measurements it is possible to estimate the length scale of receptor clusters on the cell surface. This information is useful in understanding mechanisms of leukocytes adhesion to endothelial cells as well as the effect of adhesion molecules adaptation on transmission of extracellular forces. The method also has applications in tissue engineering, drug and gene delivery, cell signaling and biocompatibility design.


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