1,709 research outputs found
Imaging the dust sublimation front of a circumbinary disk
We present the first near-IR milli-arcsecond-scale image of a post-AGB binary
that is surrounded by hot circumbinary dust. A very rich interferometric data
set in six spectral channels was acquired of IRAS08544-4431 with the new RAPID
camera on the PIONIER beam combiner at the Very Large Telescope Interferometer
(VLTI). A broadband image in the \textit{H} band was reconstructed by combining
the data of all spectral channels using the SPARCO method. We spatially
separate all the building blocks of the IRAS08544-4431 system in our
milliarcsecond-resolution image. Our dissection reveals a dust sublimation
front that is strikingly similar to that expected in early-stage protoplanetary
disks, as well as an unexpected flux signal of 4\% from the secondary
star. The energy output from this companion indicates the presence of a compact
circum-companion accretion disk, which is likely the origin of the fast outflow
detected in H. Our image provides the most detailed view into the heart
of a dusty circumstellar disk to date. Our results demonstrate that binary
evolution processes and circumstellar disk evolution can be studied in detail
in space and over time.Comment: PR @ http://www.eso.org/public/news/eso1608
Uncertainties in stellar evolution models: convective overshoot
In spite of the great effort made in the last decades to improve our
understanding of stellar evolution, significant uncertainties remain due to our
poor knowledge of some complex physical processes that require an empirical
calibration, such as the efficiency of the interior mixing related to
convective overshoot. Here we review the impact of convective overshoot on the
evolution of stars during the main Hydrogen and Helium burning phases.Comment: Proc. of the workshop "Asteroseismology of stellar populations in the
Milky Way" (Sesto, 22-26 July 2013), Astrophysics and Space Science
Proceedings, (eds. A. Miglio, L. Girardi, P. Eggenberger, J. Montalban
Coastal Sediment Dynamics Around Netravati – Gurpur River Mouth Through Integrated Approach
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv
Explicit MBR All-Symbol Locality Codes
Node failures are inevitable in distributed storage systems (DSS). To enable
efficient repair when faced with such failures, two main techniques are known:
Regenerating codes, i.e., codes that minimize the total repair bandwidth; and
codes with locality, which minimize the number of nodes participating in the
repair process. This paper focuses on regenerating codes with locality, using
pre-coding based on Gabidulin codes, and presents constructions that utilize
minimum bandwidth regenerating (MBR) local codes. The constructions achieve
maximum resilience (i.e., optimal minimum distance) and have maximum capacity
(i.e., maximum rate). Finally, the same pre-coding mechanism can be combined
with a subclass of fractional-repetition codes to enable maximum resilience and
repair-by-transfer simultaneously
Multi-Scale Convolutional Neural Network for Accurate Corneal Segmentation in Early Detection of Fungal Keratitis.
Microbial keratitis is an infection of the cornea of the eye that is commonly caused by prolonged contact lens wear, corneal trauma, pre-existing systemic disorders and other ocular surface disorders. It can result in severe visual impairment if improperly managed. According to the latest World Vision Report, at least 4.2 million people worldwide suffer from corneal opacities caused by infectious agents such as fungi, bacteria, protozoa and viruses. In patients with fungal keratitis (FK), often overt symptoms are not evident, until an advanced stage. Furthermore, it has been reported that clear discrimination between bacterial keratitis and FK is a challenging process even for trained corneal experts and is often misdiagnosed in more than 30% of the cases. However, if diagnosed early, vision impairment can be prevented through early cost-effective interventions. In this work, we propose a multi-scale convolutional neural network (MS-CNN) for accurate segmentation of the corneal region to enable early FK diagnosis. The proposed approach consists of a deep neural pipeline for corneal region segmentation followed by a ResNeXt model to differentiate between FK and non-FK classes. The model trained on the segmented images in the region of interest, achieved a diagnostic accuracy of 88.96%. The features learnt by the model emphasize that it can correctly identify dominant corneal lesions for detecting FK
Electrochemically Impregnated Aluminum-Stabilized α-Nickel Hydroxide Electrodes
Nickel-positive electrodes obtained by electrochemical impregnation of aluminum-substituted α-nickel hydroxide are found to deliver a reversible discharge capacity of ca. 450 mAh/g. This is much higher than the capacity of β-nickel hydroxide electrodes 200 mAh/g: this work; 225 mAh/g: Dixit et al., J. Power Sources, 63, 167 (1996) prepared under identical conditions and pasted electrodes comprising cobalt-doped nickel hydroxide 345 mAh/g: Faure et al., J. Power Sources, 36, 497 (1991). These observations suggest that the theoretical target-capacity for high-performance nickel-positive electrodes must be revised from the currently accepted value of 289 mAh/g (1e exchange) to 491 mAh/g 1.7e exchange: Corrigan and Knight, J. Electrochem. Soc., 136, 613 (1989). © 1999 The Electrochemical Society. S1099-0062(98)08-044-4. All rights reserved
Theory of Light Emission in Sonoluminescence as Thermal Radiation
Based on the model proposed by Hilgenfeldt {\it at al.} [Nature {\bf 398},
401 (1999)], we present here a comprehensive theory of thermal radiation in
single-bubble sonoluminescence (SBSL). We first invoke the generalized
Kirchhoff's law to obtain the thermal emissivity from the absorption
cross-section of a multilayered sphere (MLS). A sonoluminescing bubble, whose
internal structure is determined from hydrodynamic simulations, is then
modelled as a MLS and in turn the thermal radiation is evaluated. Numerical
results obtained from simulations for argon bubbles show that our theory
successfully captures the major features observed in SBSL experiments.Comment: 17 pages, 20 figure
Optimisation problems and replica symmetry breaking in finite connectivity spin-glasses
A formalism capable of handling the first step of hierarchical replica
symmetry breaking in finite-connectivity models is introduced. The emerging
order parameter is claimed to be a probability distribution over the space of
field distributions (or, equivalently magnetisation distributions) inside the
cluster of states. The approach is shown to coincide with the previous works in
the replica symmetric case and in the two limit cases m=0,1 where m is Parisi's
break-point. As an application to the study of optimization problems, the
ground-state properties of the random 3-Satisfiability problem are investigated
and we present a first RSB solution improving replica symmetric results.Comment: 16 pages Revtex file, 1 figure; amended version with two new
appendices; to be published in J.Phys.
Beach Morphological Characteristics and Coastal Processes Along Dakshina Kannada Coast, West Coast of India
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv
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