4,448 research outputs found
A flexible telerobotic system for space operations
The objective and design of a proposed goal-oriented knowledge-based telerobotic system for space operations is described. This design effort encompasses the elements of the system executive and user interface and the distribution and general structure of the knowledge base, the displays, and the task sequencing. The objective of the design effort is to provide an expandable structure for a telerobotic system that provides cooperative interaction between the human operator and computer control. The initial phase of the implementation provides a rule-based, goal-oriented script generator to interface to the existing control modes of a telerobotic research system, in the Intelligent Systems Research Lab at NASA Research Center
On the separable quotient problem for Banach spaces
While the classic separable quotient problem remains open, we survey general
results related to this problem and examine the existence of a particular
infinitedimensional separable quotient in some Banach spaces of vector-valued
functions, linear operators and vector measures. Most of the results presented
are consequence of known facts, some of them relative to the presence of
complemented copies of the classic sequence spaces c_0 and l_p, for 1 <= p <=
\infty. Also recent results of Argyros - Dodos - Kanellopoulos, and Sliwa are
provided. This makes our presentation supplementary to a previous survey (1997)
due to Mujica
A cross-correlation of WMAP and ROSAT
We cross-correlate the recent CMB WMAP 1 year data with the diffuse soft
X-ray background map of ROSAT. We look for common signatures due to galaxy
clusters (SZ effect in CMB, bremsstrahlung in X-rays) by cross-correlating the
two maps in real and in Fourier space. We do not find any significant
correlation and we explore the different reasons for this lack of correlation.
The most likely candidates are the possibility that we live in a low universe () and/or systematic effects in the data
especially in the diffuse X-ray maps which may suffer from significant cluster
signal subtraction during the point source removal process.Comment: To appear in New Astronomy Reviews, Proceedings of the CMBNET
Meeting, 20-21 February, 2003, Oxford, U
Bounded resolutions for spaces Cp(X) and a characterization in terms of X
An internal characterization of the Arkhangel’ski˘ı-Calbrixmain theorem from [4] is obtained
by showing that the space Cp(X) of continuous real-valued functions on a Tychonoff space
X is K-analytic framed in RX if and only if X admits a nice framing. This applies to show
that a metrizable (or cosmic) space X is σ -compact if and only if X has a nice framing. We
analyse a few concepts which are useful while studying nice framings. For example, a class
of Tychonoff spaces X containing strictly Lindelöf Cˇ ech-complete spaces is introduced for
which a variant of Arkhangel’ski˘ı-Calbrix theorem for σ-boundedness of X is shown
Cosmological constraints from the cluster contribution to the power spectrum of the soft X-ray background. New evidence for a low sigma_8
We use the X-ray power spectrum of the ROSAT all-sky survey in the R6 band
(approximately 0.9-1.3 keV) to set an upper limit on the galaxy cluster power
spectrum. The cluster power spectrum is modelled with a minimum number of
robust assumptions regarding the structure of the clusters. The power spectrum
of ROSAT sets an upper limit on the Omega_m-sigma_8 plane which excludes all
the models with sigma_8 above sigma_8 = 0.5/(Omega_m^0.38) in a flat LCDM
universe. We discuss the possible sources of systematic errors in our
conclusions, mainly dominated by the assumed L_x-T relation. Alternatively,
this relation could be constrained by using the X-ray power spectrum, if the
cosmological model is known. Our conclusions suggest that only models with a
low value of sigma_8 (sigma_8 < 0.8 for Omega_m = 0.3) may be compatible with
our upper limit. We also find that models predicting lower luminosities in
galaxy clusters are favoured. Reconciling our cosmological constraints with
these arising by other methods might require either a high entropy floor or
wide-spread presence of cooling flows in the low-redshift clusters.Comment: 14 pages, 19 plots (2 as gif files). MNRAS submitte
Robust concurrent remote entanglement between two superconducting qubits
Entangling two remote quantum systems which never interact directly is an
essential primitive in quantum information science and forms the basis for the
modular architecture of quantum computing. When protocols to generate these
remote entangled pairs rely on using traveling single photon states as carriers
of quantum information, they can be made robust to photon losses, unlike
schemes that rely on continuous variable states. However, efficiently detecting
single photons is challenging in the domain of superconducting quantum circuits
because of the low energy of microwave quanta. Here, we report the realization
of a robust form of concurrent remote entanglement based on a novel microwave
photon detector implemented in the superconducting circuit quantum
electrodynamics (cQED) platform of quantum information. Remote entangled pairs
with a fidelity of are generated at Hz. Our experiment
opens the way for the implementation of the modular architecture of quantum
computation with superconducting qubits.Comment: Main paper: 7 pages, 4 figures; Appendices: 14 pages, 9 figure
Peripartum cardiomyopathy: Disease or syndrome?
Peripartum cardiomyopathy (PPCM) is a rare form of pregnancy-associated heart failure and is considered to be a diagnosis of exclusion. There are many hypotheses on the aetiology of PPCM; however, the exact pathophysiological mechanism remains unknown. It shows many resemblances to other conditions, such as familial dilated cardiomyopathy or myocarditis, and therefore it can be hard to make a definite diagnosis. We describe four cases of peripartum-onset heart failure in women who were suspected of having PPCM. We discuss the differential diagnosis, pathophysiological mechanisms and various diagnostic modalities
The SZ effect contribution to WMAP. A Cross-Correlation between WMAP and ROSAT
We cross-correlate WMAP and ROSAT diffuse X-ray background maps and look for
common features in both data sets. We use the power spectrum of the product
maps and the cross-power spectrum to highlight a possible correlation. The
power spectrum of the product maps does not detect any correlation and the
cross-power spectrum does not show any significant deviation from 0. We explore
different explanations for this lack of correlation. A universe with a low
value of Sigma_8 could naturally explain the lack of correlation. We also
discuss the systematic effects which can affect this result, in particular the
subtraction of some cluster signal from the ROSAT diffuse maps which could
significantly suppress the correlation signal. These systematic effects reduce
considerably the significance of our constraints on the cosmological model.
When we include the systematic effects we find a weaker constrain on Sigma_8
allowing models with values as large as Sigma_8=1 (for Omega_m = 0.3) to be
consistent with the lack of correlation. To illustrate the capabilities of the
method with future high-quality data, we show how from the correlation signal
it should be possible to predict the level of contamination of the SZ effect on
the power spectrum of the CMB. Within the systematic errors we find evidence
that this contribution is negligible for WMAP and is expected to be small in
experiments like ACBAR or CBI, but can be important for future high resolution
experiments.Comment: This is the accepted version of the pape
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