394 research outputs found
Entire curves avoiding given sets in C^n
Let be a proper closed subset of and
at most countable (). We give conditions
of and , under which there exists a holomorphic immersion (or a proper
holomorphic embedding) with .Comment: 10 page
The COSMOS AGN Spectroscopic Survey I: XMM Counterparts
We present optical spectroscopy for an X-ray and optical flux-limited sample
of 677 XMM-Newton selected targets covering the 2 deg^2 COSMOS field, with a
yield of 485 high-confidence redshifts. The majority of the spectra were
obtained over three seasons (2005-2007) with the IMACS instrument on the
Magellan (Baade) telescope. We also include in the sample previously published
Sloan Digital Sky Survey spectra and supplemental observations with
MMT/Hectospec. We detail the observations and classification analyses. The
survey is 90% complete to flux limits of f_{0.5-10 keV}>8 x 10^-16 erg cm^-2
s^-1 and i_AB+<22, where over 90% of targets have high-confidence redshifts.
Making simple corrections for incompleteness due to redshift and spectral type
allows for a description of the complete population to $i_AB+<23. The corrected
sample includes 57% broad emission line (Type 1, unobscured) AGN at
0.13<z<4.26, 25% narrow emission line (Type 2, obscured) AGN at 0.07<z<1.29,
and 18% absorption line (host-dominated, obscured) AGN at 0<z<1.22 (excluding
the stars that made up 4% of the X-ray targets). We show that the survey's
limits in X-ray and optical flux include nearly all X-ray AGN (defined by
L_{0.5-10 keV}>3 x 10^42 erg s^-1) to z<1, of both optically obscured and
unobscured types. We find statistically significant evidence that the obscured
to unobscured AGN ratio at z<1 increases with redshift and decreases with
luminosity.Comment: Accepted for publication in the ApJ. 31 pages, 17 figures. Table 2 is
available on reques
Fermi-liquid instabilities at magnetic quantum phase transitions
This review discusses instabilities of the Fermi-liquid state of conduction
electrons in metals with particular emphasis on magnetic quantum critical
points. Both the existing theoretical concepts and experimental data on
selected materials are presented; with the aim of assessing the validity of
presently available theory. After briefly recalling the fundamentals of
Fermi-liquid theory, the local Fermi-liquid state in quantum impurity models
and their lattice versions is described. Next, the scaling concepts applicable
to quantum phase transitions are presented. The Hertz-Millis-Moriya theory of
quantum phase transitions is described in detail. The breakdown of the latter
is analyzed in several examples. In the final part experimental data on
heavy-fermion materials and transition-metal alloys are reviewed and confronted
with existing theory.Comment: 62 pages, 29 figs, review article for Rev. Mod. Phys; (v2) discussion
extended, refs added; (v3) shortened; final version as publishe
The Nature of Optically Dull Active Galactic Nuclei in COSMOS
We present infrared, optical, and X-ray data of 48 X-ray bright, optically
dull AGNs in the COSMOS field. These objects exhibit the X-ray luminosity of an
active galactic nucleus (AGN) but lack broad and narrow emission lines in their
optical spectrum. We show that despite the lack of optical emission lines, most
of these optically dull AGNs are not well-described by a typical passive red
galaxy spectrum: instead they exhibit weak but significant blue emission like
an unobscured AGN. Photometric observations over several years additionally
show significant variability in the blue emission of four optically dull AGNs.
The nature of the blue and infrared emission suggest that the optically
inactive appearance of these AGNs cannot be caused by obscuration intrinsic to
the AGNs. Instead, up to ~70% of optically dull AGNs are diluted by their
hosts, with bright or simply edge-on hosts lying preferentially within the
spectroscopic aperture. The remaining ~30% of optically dull AGNs have
anomalously high f_x/f_o ratios and are intrinsically weak, not obscured, in
the optical. These optically dull AGNs are best described as a weakly accreting
AGN with a truncated accretion disk from a radiatively inefficient accretion
flow.Comment: 12 pages, 10 figures. Accepted for publication in the Ap
Coincidence analysis to search for inspiraling compact binaries using TAMA300 and LISM data
Japanese laser interferometric gravitational wave detectors, TAMA300 and
LISM, performed a coincident observation during 2001. We perform a coincidence
analysis to search for inspiraling compact binaries. The length of data used
for the coincidence analysis is 275 hours when both TAMA300 and LISM detectors
are operated simultaneously. TAMA300 and LISM data are analyzed by matched
filtering, and candidates for gravitational wave events are obtained. If there
is a true gravitational wave signal, it should appear in both data of detectors
with consistent waveforms characterized by masses of stars, amplitude of the
signal, the coalescence time and so on. We introduce a set of coincidence
conditions of the parameters, and search for coincident events. This procedure
reduces the number of fake events considerably, by a factor
compared with the number of fake events in single detector analysis. We find
that the number of events after imposing the coincidence conditions is
consistent with the number of accidental coincidences produced purely by noise.
We thus find no evidence of gravitational wave signals. We obtain an upper
limit of 0.046 /hours (CL ) to the Galactic event rate within 1kpc from
the Earth. The method used in this paper can be applied straightforwardly to
the case of coincidence observations with more than two detectors with
arbitrary arm directions.Comment: 28 pages, 17 figures, Replaced with the version to be published in
Physical Review
Colour reconnection in e+e- -> W+W- at sqrt(s) = 189 - 209 GeV
The effects of the final state interaction phenomenon known as colour
reconnection are investigated at centre-of-mass energies in the range sqrt(s) ~
189-209 GeV using the OPAL detector at LEP. Colour reconnection is expected to
affect observables based on charged particles in hadronic decays of W+W-.
Measurements of inclusive charged particle multiplicities, and of their angular
distribution with respect to the four jet axes of the events, are used to test
models of colour reconnection. The data are found to exclude extreme scenarios
of the Sjostrand-Khoze Type I (SK-I) model and are compatible with other
models, both with and without colour reconnection effects. In the context of
the SK-I model, the best agreement with data is obtained for a reconnection
probability of 37%. Assuming no colour reconnection, the charged particle
multiplicity in hadronically decaying W bosons is measured to be (nqqch) =
19.38+-0.05(stat.)+-0.08 (syst.).Comment: 30 pages, 9 figures, Submitted to Euro. Phys. J.
Search for the Standard Model Higgs Boson with the OPAL Detector at LEP
This paper summarises the search for the Standard Model Higgs boson in e+e-
collisions at centre-of-mass energies up to 209 GeV performed by the OPAL
Collaboration at LEP. The consistency of the data with the background
hypothesis and various Higgs boson mass hypotheses is examined. No indication
of a signal is found in the data and a lower bound of 112.7GeV/C^2 is obtained
on the mass of the Standard Model Higgs boson at the 95% CL.Comment: 51 pages, 21 figure
The Energy Landscape, Folding Pathways and the Kinetics of a Knotted Protein
The folding pathway and rate coefficients of the folding of a knotted protein
are calculated for a potential energy function with minimal energetic
frustration. A kinetic transition network is constructed using the discrete
path sampling approach, and the resulting potential energy surface is
visualized by constructing disconnectivity graphs. Owing to topological
constraints, the low-lying portion of the landscape consists of three distinct
regions, corresponding to the native knotted state and to configurations where
either the N- or C-terminus is not yet folded into the knot. The fastest
folding pathways from denatured states exhibit early formation of the
N-terminus portion of the knot and a rate-determining step where the C-terminus
is incorporated. The low-lying minima with the N-terminus knotted and the
C-terminus free therefore constitute an off-pathway intermediate for this
model. The insertion of both the N- and C-termini into the knot occur late in
the folding process, creating large energy barriers that are the rate limiting
steps in the folding process. When compared to other protein folding proteins
of a similar length, this system folds over six orders of magnitude more
slowly.Comment: 19 page
Results of the search for inspiraling compact star binaries from TAMA300's observation in 2000-2004
We analyze the data of TAMA300 detector to search for gravitational waves
from inspiraling compact star binaries with masses of the component stars in
the range 1-3Msolar. In this analysis, 2705 hours of data, taken during the
years 2000-2004, are used for the event search. We combine the results of
different observation runs, and obtained a single upper limit on the rate of
the coalescence of compact binaries in our Galaxy of 20 per year at a 90%
confidence level. In this upper limit, the effect of various systematic errors
such like the uncertainty of the background estimation and the calibration of
the detector's sensitivity are included.Comment: 8 pages, 4 Postscript figures, uses revtex4.sty The author list was
correcte
Measurement of the Hadronic Photon Structure Function F_2^gamma at LEP2
The hadronic structure function of the photon F_2^gamma is measured as a
function of Bjorken x and of the factorisation scale Q^2 using data taken by
the OPAL detector at LEP. Previous OPAL measurements of the x dependence of
F_2^gamma are extended to an average Q^2 of 767 GeV^2. The Q^2 evolution of
F_2^gamma is studied for average Q^2 between 11.9 and 1051 GeV^2. As predicted
by QCD, the data show positive scaling violations in F_2^gamma. Several
parameterisations of F_2^gamma are in agreement with the measurements whereas
the quark-parton model prediction fails to describe the data.Comment: 4 pages, 2 figures, to appear in the proceedings of Photon 2001,
Ascona, Switzerlan
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