4,887 research outputs found
On the Connection Between 2d Topological Gravity and the Reduced Hermitian Matrix Model
We discuss how concepts such as geodesic length and the volume of space-time
can appear in 2d topological gravity. We then construct a detailed mapping
between the reduced Hermitian matrix model and 2d topological gravity at genus
zero. This leads to a complete solution of the counting problem for planar
graphs with vertices of even coordination number. The connection between
multi-critical matrix models and multi-critical topological gravity at genus
zero is studied in some detail.Comment: 29 pages, LaTe
A sound card based multi-channel frequency measurement system
For physical processes which express themselves as a frequency, for example
magnetic field measurements using optically-pumped alkali-vapor magnetometers,
the precise extraction of the frequency from the noisy signal is a classical
problem. We describe herein a frequency measurement system based on an
inexpensive commercially available computer sound card coupled with a software
single-tone estimator which reaches Cram\'er--Rao limited performance, a
feature which commercial frequency counters often lack. Characterization of the
system and examples of its successful application to magnetometry are
presented.Comment: 4 pages, 3 figures, 1 tabl
Asymptotic behavior of integral equations using monotonicity
AbstractIn this paper, some Volterra integral equations that arise in heat transfer are studied. In particular, sufficient conditions for asymptotically periodic solutions are given. The results are derived, in part, using the fact that the resolvent form of the equations involved yields a monotone operator
Correlated electron tunneling through two separate quantum dot systems with strong capacitive interdot coupling
A system consisting of two independently contacted quantum dots with strong
electrostatic interaction shows interdot Coulomb blockade when the dots are
weakly tunnel coupled to their leads. It is studied experimentally how the
blockade can be overcome by correlated tunneling when tunnel coupling to the
leads increases. The experimental results are compared with numerical
renormalization group calculations using predefined (measured) parameters. Our
results indicate Kondo correlations due to the electrostatic interaction in
this double quantum dot system.Comment: 5 pages, 3 figures, published in Phys. Rev. Lett. Oct. 30t
Analysis of conditional gene deletion using probe based Real-Time PCR
Following publication of this article [1] the authors noticed that an incorrect probe reference was cited on page 3, 4, 5 and 6 ("UP #69, Roche Applied Science"). The correct probe that was used for the 1lox/2lox allele ratio analysis in the paper is as follow
A large sample study of spin relaxation and magnetometric sensitivity of paraffin-coated Cs vapor cells
We have manufactured more than 250 nominally identical paraffin-coated Cs
vapor cells (30 mm diameter bulbs) for multi-channel atomic magnetometer
applications. We describe our dedicated cell characterization apparatus. For
each cell we have determined the intrinsic longitudinal, \sGamma{01}, and
transverse, \sGamma{02}, relaxation rates. Our best cell shows
\sGamma{01}/2\pi\approx 0.5 Hz, and \sGamma{02}/2\pi\approx 2 Hz. We find a
strong correlation of both relaxation rates which we explain in terms of
reservoir and spin exchange relaxation. For each cell we have determined the
optimal combination of rf and laser powers which yield the highest sensitivity
to magnetic field changes. Out of all produced cells, 90% are found to have
magnetometric sensitivities in the range of 9 to 30 fTHz. Noise analysis shows
that the magnetometers operated with such cells have a sensitivity close to the
fundamental photon shot noise limit
Eta Carinae across the 2003.5 Minimum: Analysis in the visible and near infrared spectral region
We present an analysis of the visible through near infrared spectrum of Eta
Carinae and its ejecta obtained during the "Eta Carinae Campaign with the UVES
at the ESO VLT". This is a part of larger effort to present a complete Eta
Carinae spectrum, and extends the previously presented analyses with the
HST/STIS in the UV (1240-3159 A) to 10,430 A. The spectrum in the mid and near
UV is characterized by the ejecta absorption. At longer wavelengths, stellar
wind features from the central source and narrow emission lines from the
Weigelt condensations dominate the spectrum. However, narrow absorption lines
from the circumstellar shells are present. This paper provides a description of
the spectrum between 3060 and 10,430 A, including line identifications of the
ejecta absorption spectrum, the emission spectrum from the Weigelt
condensations and the P-Cygni stellar wind features. The high spectral
resolving power of VLT/UVES enables equivalent width measurements of atomic and
molecular absorption lines for elements with no transitions at the shorter
wavelengths. However, the ground based seeing and contributions of nebular
scattered radiation prevent direct comparison of measured equivalent widths in
the VLT/UVES and HST/STIS spectra. Fortunately, HST/STIS and VLT/UVES have a
small overlap in wavelength coverage which allows us to compare and adjust for
the difference in scattered radiation entering the instruments' apertures. This
paper provides a complete online VLT/UVES spectrum with line identifications
and a spectral comparison between HST/STIS and VLT/UVES between 3060 and 3160
A.Comment: 13 pages, 11 figures + atlas. The paper accepted for the ApJS and is
accompanied with an atlas in the online edition pape
Synthesis and Modification of structured molybdenum oxide-composite nanoparticles in an integrated CVS/CVD process
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