7,918 research outputs found
On the Evolution, Numbers, and Characteristics of Close-Binary Supersoft Sources
The ability to perform detailed evolutionary calculations is essential to the
development of a well-defined and testable binary model. Unfortunately,
traditional evolutionary calculations cannot be used to follow a significant
fraction of possible close-binary supersoft sources (CBSSs). It is therefore
important to examine the input physics carefully, to be sure that all relevant
and potentially important physical processes are included. In this paper we
continue a line of research begun last year, and explore the role that winds
are expected to play in the evolution of CBSSs. We find that at least a subset
of the systems that seemed to be candidates for common envelope evolution may
survive, if radiation emitted by white dwarf drives winds from the system. We
study the effects of winds on the binary evolution of CBSSs, and compute the
number and characteristics of CBSSs expected to be presently active in galaxies
such as our own or M31.Comment: 13 pages; figures included in 0.33 M postscript file; in Supersoft
X-ray Sources, ed. J. Greiner (Springer-Verlag: Berlin) (1996
Brittle fracture down to femto-Joules - and below
We analyze large sets of energy-release data created by stress-induced
brittle fracture in a pure sapphire crystal at close to zero temperature where
stochastic fluctuations are minimal. The waiting-time distribution follows that
observed for fracture in rock and for earthquakes. Despite strong time
correlations of the events and the presence of large-event precursors, simple
prediction algorithms only succeed in a very weak probabilistic sense. We also
discuss prospects for further cryogenic experiments reaching close to
single-bond sensitivity and able to investigate the existence of a
transition-stress regime.Comment: REVTeX, new figure added, minor modifications to tex
Shedding Light on Diatom Photonics by means of Digital Holography
Diatoms are among the dominant phytoplankters in the worl's ocean, and their
external silica investments, resembling artificial photonics crystal, are
expected to play an active role in light manipulation. Digital holography
allowed studying the interaction with light of Coscinodiscus wailesii cell wall
reconstructing the light confinement inside the cell cytoplasm, condition that
is hardly accessible via standard microscopy. The full characterization of the
propagated beam, in terms of quantitative phase and intensity, removed a
long-standing ambiguity about the origin of the light. The data were discussed
in the light of living cell behavior in response to their environment
Measurement of constant radius swept features in cultural heritage
none3The dimensional characterization of archaeological fragment is a very complex
operation and could prove to be useful for identifying the presence of standard attributes in the
ceramics found from a specific archaeological site, or for making comparisons and analysis of
similarities or for studying ancient technologies used for manufacture of objects. The
dimensional analysis of the fragments is now carried out manually with traditional measuring
devices. Typically, the results obtained are inaccurate and non-repeatable measurements.
This paper focuses on the dimensional characterization of a specific geometric class of features:
the constant radius swept features (called here CRS features). Several archaeological features,
such as rims, bases, decorative motifs, processing marks and grooves are referable from a
geometric point of view to the class of CRS features. These are detail features, which may be
very interesting for the investigation of some aspects related to the historical-archaeological
classification of the find. CRS features are often found on worn, damaged (e.g. chipped) or
fragmented objects; they are frequently characterized, from a geometric point of view, by free
form surfaces and by a limited cross sectional extension. In some cases, CRS features can be of
axially symmetrical geometry: this occurs quite frequently in the case of archaeological pottery.
For all these reasons, it is often difficult to apply traditional manual methods for the quantitative
dimensional characterization of CRS features.
This paper describes an original methodology for the measurement of CRS features acquired by
scanning technologies. The algorithmic implementation of this methodology, consisting of a
suitable processing of the feature nodes, allows to carry out automatically the dimensional
characterization of the feature.Di Angelo L., Di Stefano P., Morabito A.E.Di Angelo, L.; Di Stefano, P.; Morabito, A. E
automatic features recognition for anthropometry
Abstract For the purpose of reducing uncertainties in the measurements of morphologically complex biological objects, the authors present a new automatic method, which takes advantage from the representation of the object in the form of the 3D geometric model obtained from CT-scans or 3D scanning. In this paper, the method is verified in real cases and compared with the traditional approaches
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