2,597 research outputs found
Towards the Refinement of Von Neumann Machines
Mathematicians agree that certifiable configurations are an interesting new topic in the field of programming languages, and scholars concur. Given the current status of atomic modalities, programmers dubiously desire the synthesis of replication. In or- der to accomplish this intent, we describe a distributed tool for analyzing context-free grammar (Tor), verifying that the little- known collaborative algorithm for the em- ulation of the Internet by M. Garey et al. [3] is in Co-NP
Suzaku Observations of Local Ultraluminous Infrared Galaxies
We report the results from our analysis of {\it Suzaku} XIS (0.5-10 keV) and
HXD/PIN (15-40 keV) observations of five well-known local ULIRGs: {\em IRAS}
F05189-2524, {\em IRAS} F08572+3915, Mrk 273, PKS 1345+12, and Arp 220. The XIS
observations of F05189-2524 and Mrk 273 reveal strong iron lines consistent
with Fe K and changes in spectral shapes with respect to previous {\it
Chandra} and {\it XMM-Newton} observations. Mrk 273 is also detected by the
HXD/PIN at 1.8-. For F05189-2524, modeling of the data from the
different epochs suggests that the change in spectral shape is likely due to
the central source switching off, leaving behind a residual reflection
spectrum, or an increase in the absorbing column. An increase in the covering
fraction of the absorber can describe the spectral variations seen in Mrk 273,
although a reduction in the intrinsic AGN luminosity cannot be formally ruled
out. The {\it Suzaku} spectra of Mrk 273 are well fit by a ~94% covering
fraction model with a column density of cm. The
absorption-corrected log[ / ] ratio is consistent
with those found in PG Quasars. The 0.5-10 keV spectrum of PKS 1345+12 and Arp
220 seem unchanged from previous observations and their hard X-ray emission is
not convincingly detected by the HXD/PIN. The large column density derived from
CO observations and the large equivalent width of an ionized Fe line in Arp 220
can be reconciled by an ionized reflection model. F08572+3915 is undetected in
both the XIS and HXD/PIN, but the analysis of unpublished {\em Chandra} data
provides a new measurement at low energies.Comment: 37 pages including 4 tables and 10 figures. Accepted for publication
in ApJ. It is tentatively scheduled to appear in the January 20, 2009 issue
of Ap
Kinematic classifications of local interacting galaxies: implications for the merger/disk classifications at high-z
The classification of galaxy mergers and isolated disks is key for
understanding the relative importance of galaxy interactions and secular
evolution during the assembly of galaxies. The kinematic properties of galaxies
as traced by emission lines have been used to suggest the existence of a
significant population of high-z star-forming galaxies consistent with isolated
rotating disks. However, recent studies have cautioned that post-coalescence
mergers may also display disk-like kinematics. To further investigate the
robustness of merger/disk classifications based on kinematic properties, we
carry out a systematic classification of 24 local (U)LIRGs spanning a range of
galaxy morphologies: from isolated spiral galaxies, ongoing interacting
systems, to fully merged remnants. We artificially redshift the WiFeS
observations of these local (U)LIRGs to z=1.5 to make a realistic comparison
with observations at high-z, and also to ensure that all galaxies have the same
spatial sampling of ~900 pc. Using both kinemetry-based and visual
classifications, we find that the reliability of kinematic classification shows
a strong trend with the interaction stage of galaxies. Mergers with two nuclei
and tidal tails have the most distinct kinematic properties compared to
isolated disks, whereas a significant population of the interacting disks and
merger remnants are indistinguishable from isolated disks. The high fraction of
late-stage mergers showing disk-like kinematics reflects the complexity of the
dynamics during galaxy interactions. However, the exact fractions of
misidentified disks and mergers depend on the definition of kinematic
asymmetries and the classification threshold when using kinemetry-based
classifications. Our results suggest that additional indicators such as
morphologies traced by stars or molecular gas are required to further constrain
the merger/disk classifications at high-z.Comment: 16 pages, 5 figures, ApJ accepte
A controlled study of cold dust content in galaxies from
At , the formation of new stars is dominated by dusty galaxies whose
far-IR emission indicates they contain colder dust than local galaxies of a
similar luminosity. We explore the reasons for the evolving IR emission of
similar galaxies over cosmic time using: 1) Local galaxies from GOALS ; 2) Galaxies at from the 5MUSES
(); 3) IR luminous galaxies spanning
from GOODS and Spitzer xFLS (). All
samples have Spitzer mid-IR spectra, and Herschel and ground-based
submillimeter imaging covering the full IR spectral energy distribution,
allowing us to robustly measure ,
, and for every galaxy. Despite similar infrared
luminosities, dusty star forming galaxies have a factor of 5 higher
dust masses and 5K colder temperatures. The increase in dust mass is linked
with an increase in the gas fractions with redshift, and we do not observe a
similar increase in stellar mass or star formation efficiency.
, a proxy
for , is strongly correlated with independently of redshift. We
measure merger classification and galaxy size for a subsample, and there is no
obvious correlation between these parameters and or . In dusty star forming galaxies, the
change in can fully
account for the observed colder dust temperatures, suggesting that any change
in the spatial extent of the interstellar medium is a second order effect.Comment: Accepted for publication in ApJ. 21 pages, 11 figure
Study design considerations for the Standardized Treatment of Pulmonary Exacerbations 2 (STOP2): A trial to compare intravenous antibiotic treatment durations in CF
BACKGROUND:
Pulmonary exacerbations (PEx) in cystic fibrosis (CF) are common and contribute to morbidity and mortality. Duration of IV antibiotic therapy to treat PEx varies widely in the US, and there are few data to guide treatment decisions.
METHODS:
We combined a survey of CF stakeholders with retrospective analyses of a recent observational study of CF PEx to design a multicenter, randomized, prospective study comparing the efficacy and safety of different durations of IV antibiotics for PEx to meet the needs of people with CF and their caregivers.
RESULTS:
IV antibiotic duration was cited as the most important PEx research question by responding CF physicians and top concern among surveyed CF patients/caregivers. During PEx, forced expiratory volume in 1s (FEV1% predicted) and symptom responses at 7-10days of IV antibiotics identified two distinct groups: early robust responders (ERR) who subsequently experienced greater FEV1 improvements compared to non-ERR (NERR). In addition to greater FEV1 and symptom responses, only 14% of ERR patients were treated with IV antibiotics for >15days, compared with 45% of NERR patients.
CONCLUSIONS:
A divergent trial design that evaluates subjects' interim improvement in FEV1 and symptoms to tailor randomization to IV treatment duration (10 vs. 14days for ERR, 14 vs. 21days for NERR) may alleviate physician and patient concerns about excess or inadequate treatment. Such a study has the potential to provide evidence necessary to standardize IV antibiotic duration in CF PEx care -a first step to conducting PEx research of other treatment features
Water rate structure: A tool for water conservation in Oklahoma
The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311
On the spin-statistics connection in curved spacetimes
The connection between spin and statistics is examined in the context of locally covariant quantum field theory. A generalization is proposed in which locally covariant theories are defined as functors from a category of framed spacetimes to a category of ∗-algebras. This allows for a more operational description of theories with spin, and for the derivation of a more general version of the spin-statistics connection in curved spacetimes than previously available. The proof involves a "rigidity argument" that is also applied in the standard setting of locally covariant quantum field theory to show how properties such as Einstein causality can be transferred from Minkowski spacetime to general curved spacetimes
Dynamics of entanglement for coherent excitonic states in a system of two coupled quantum dots and cavity QED
The dynamics of the entanglement for coherent excitonic states in the system
of two coupled large semiconductor quantum dots () mediated by a
single-mode cavity field is investigated. Maximally entangled coherent
excitonic states can be generated by cavity field initially prepared in odd
coherent state. The entanglement of the excitonic coherent states between two
dots reaches maximum when no photon is detected in the cavity. The effects of
the zero-temperature environment on the entanglement of excitonic coherent
state are also studied using the concurrence for two subsystems of the excitonsComment: 7 pages, 6 figure
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