31 research outputs found
COMAP Early Science: VI. A First Look at the COMAP Galactic Plane Survey
We present early results from the COMAP Galactic Plane Survey conducted
between June 2019 and April 2021, spanning in Galactic
longitude and |b|<1.\!\!^{\circ}5 in Galactic latitude with an angular
resolution of . The full survey will span -
and will be the first large-scale radio continuum survey at
GHz with sub-degree resolution. We present initial results from the first part
of the survey, including diffuse emission and spectral energy distributions
(SEDs) of HII regions and supernova remnants. Using low and high frequency
surveys to constrain free-free and thermal dust emission contributions, we find
evidence of excess flux density at GHz in six regions that we interpret
as anomalous microwave emission. Furthermore we model UCHII contributions using
data from the GHz CORNISH catalogue and reject this as the cause of the
GHz excess. Six known supernova remnants (SNR) are detected at GHz,
and we measure spectral indices consistent with the literature or show evidence
of steepening. The flux density of the SNR W44 at GHz is consistent with
a power-law extrapolation from lower frequencies with no indication of spectral
steepening in contrast with recent results from the Sardinia Radio Telescope.
We also extract five hydrogen radio recombination lines to map the warm ionized
gas, which can be used to estimate electron temperatures or to constrain
continuum free-free emission. The full COMAP Galactic plane survey, to be
released in 2023/2024, will be an invaluable resource for Galactic
astrophysics.Comment: Paper 6 of 7 in series. 28 pages, 10 figures, submitted to Ap
COMAP Early Science: IV. Power Spectrum Methodology and Results
We present the power spectrum methodology used for the first-season COMAP
analysis, and assess the quality of the current data set. The main results are
derived through the Feed-feed Pseudo-Cross-Spectrum (FPXS) method, which is a
robust estimator with respect to both noise modeling errors and experimental
systematics. We use effective transfer functions to take into account the
effects of instrumental beam smoothing and various filter operations applied
during the low-level data processing. The power spectra estimated in this way
have allowed us to identify a systematic error associated with one of our two
scanning strategies, believed to be due to residual ground or atmospheric
contamination. We omit these data from our analysis and no longer use this
scanning technique for observations. We present the power spectra from our
first season of observing and demonstrate that the uncertainties are
integrating as expected for uncorrelated noise, with any residual systematics
suppressed to a level below the noise. Using the FPXS method, and combining
data on scales we estimate , the first direct 3D
constraint on the clustering component of the CO(1-0) power spectrum in the
literature.Comment: Paper 4 of 7 in series. 18 pages, 11 figures, as accepted in Ap
COMAP Early Science: III. CO Data Processing
We describe the first season COMAP analysis pipeline that converts raw
detector readouts to calibrated sky maps. This pipeline implements four main
steps: gain calibration, filtering, data selection, and map-making. Absolute
gain calibration relies on a combination of instrumental and astrophysical
sources, while relative gain calibration exploits real-time total-power
variations. High efficiency filtering is achieved through spectroscopic
common-mode rejection within and across receivers, resulting in nearly
uncorrelated white noise within single-frequency channels. Consequently,
near-optimal but biased maps are produced by binning the filtered time stream
into pixelized maps; the corresponding signal bias transfer function is
estimated through simulations. Data selection is performed automatically
through a series of goodness-of-fit statistics, including and
multi-scale correlation tests. Applying this pipeline to the first-season COMAP
data, we produce a dataset with very low levels of correlated noise. We find
that one of our two scanning strategies (the Lissajous type) is sensitive to
residual instrumental systematics. As a result, we no longer use this type of
scan and exclude data taken this way from our Season 1 power spectrum
estimates. We perform a careful analysis of our data processing and observing
efficiencies and take account of planned improvements to estimate our future
performance. Power spectrum results derived from the first-season COMAP maps
are presented and discussed in companion papers.Comment: Paper 3 of 7 in series. 26 pages, 23 figures, submitted to Ap
COMAP Early Science: II. Pathfinder Instrument
Line intensity mapping (LIM) is a new technique for tracing the global
properties of galaxies over cosmic time. Detection of the very faint signals
from redshifted carbon monoxide (CO), a tracer of star formation, pushes the
limits of what is feasible with a total-power instrument. The CO Mapping
Project (COMAP) Pathfinder is a first-generation instrument aiming to prove the
concept and develop the technology for future experiments, as well as
delivering early science products. With 19 receiver channels in a hexagonal
focal plane arrangement on a 10.4 m antenna, and an instantaneous 26-34 GHz
frequency range with 2 MHz resolution, it is ideally suited to measuring
CO(=1-0) from . In this paper we discuss strategies for designing
and building the Pathfinder and the challenges that were encountered. The
design of the instrument prioritized LIM requirements over those of ancillary
science. After a couple of years of operation, the instrument is well
understood, and the first year of data is already yielding useful science
results. Experience with this Pathfinder will drive the design of the next
generations of experiments.Comment: Paper 2 of 7 in series. 27 pages, 28 figures, submitted to Ap
COMAP Early Science: I. Overview
The CO Mapping Array Project (COMAP) aims to use line intensity mapping of
carbon monoxide (CO) to trace the distribution and global properties of
galaxies over cosmic time, back to the Epoch of Reionization (EoR). To validate
the technologies and techniques needed for this goal, a Pathfinder instrument
has been constructed and fielded. Sensitive to CO(1-0) emission from
- and a fainter contribution from CO(2-1) at -8, the
Pathfinder is surveying deg in a 5-year observing campaign to detect
the CO signal from . Using data from the first 13 months of observing,
we estimate on scales - the first direct
3D constraint on the clustering component of the CO(1-0) power spectrum. Based
on these observations alone, we obtain a constraint on the amplitude of the
clustering component (the squared mean CO line temperature-bias product) of
K - nearly an order-of-magnitude improvement
on the previous best measurement. These constraints allow us to rule out two
models from the literature. We forecast a detection of the power spectrum after
5 years with signal-to-noise ratio (S/N) 9-17. Cross-correlation with an
overlapping galaxy survey will yield a detection of the CO-galaxy power
spectrum with S/N of 19. We are also conducting a 30 GHz survey of the Galactic
plane and present a preliminary map. Looking to the future of COMAP, we examine
the prospects for future phases of the experiment to detect and characterize
the CO signal from the EoR.Comment: Paper 1 of 7 in series. 18 pages, 16 figures, submitted to Ap
Clinical outcomes and response to treatment of patients receiving topical treatments for pyoderma gangrenosum: a prospective cohort study
Background: pyoderma gangrenosum (PG) is an uncommon dermatosis with a limited evidence base for treatment.
Objective: to estimate the effectiveness of topical therapies in the treatment of PG.
Methods: prospective cohort study of UK secondary care patients with a clinical diagnosis of PG suitable for topical treatment (recruited July 2009 to June 2012). Participants received topical therapy following normal clinical practice (mainly Class I-III topical corticosteroids, tacrolimus 0.03% or 0.1%). Primary outcome: speed of healing at 6 weeks. Secondary outcomes: proportion healed by 6 months; time to healing; global assessment; inflammation; pain; quality-of-life; treatment failure and recurrence.
Results: Sixty-six patients (22 to 85 years) were enrolled. Clobetasol propionate 0.05% was the most commonly prescribed therapy. Overall, 28/66 (43.8%) of ulcers healed by 6 months. Median time-to-healing was 145 days (95% CI: 96 days, ∞). Initial ulcer size was a significant predictor of time-to-healing (hazard ratio 0.94 (0.88;80 1.00); p = 0.043). Four patients (15%) had a recurrence.
Limitations: No randomised comparator
Conclusion: Topical therapy is potentially an effective first-line treatment for PG that avoids possible side effects associated with systemic therapy. It remains unclear whether more severe disease will respond adequately to topical therapy alone
A Syrian Coinage of Mu'awiya ?
Summary. — The so-called « Arab-Byzantine » coinage contains a complex series of undated and anonymous coins with types derived from the Byzantine, straek between the Arab conquest of the 640 's and the reforms of Abd al-Malik of 693. The most serious attempt to establish a chronology has assigned them to the last years of this period. Historical sources and documents, however, indicate that the Islamic government was already highly organized and bureaucratic under the great leader Mu'awiya (661-680). A sophisticated system of administration and taxation implies coinage, and parallels with the East, where the «Arab-Sassanian» coinage was flourishing under Mu'awiya suggest that such was the case in Syria. I propose here that the bronze « Arab-Byzantine » types with bilingual inscriptions and mintmarks represent such an organization and may, along with a few rare gold coins, be assigned to the reign of Mu'awiya.Fig. 9 Fig. 10 Fig. 12 Fig. 11 Fig. 13Foss C. A Syrian Coinage of Mu'awiya ?. In: Revue numismatique, 6e série - Tome 158, année 2002 pp. 353-365
The defenses of Asia minor against the Turks.
Donated by Klaus KreiserReprinted from : The Greek Orthodox Theological Review, Vol.27, No.2
Emperors named Constantine
Summary. — The Byzantine habit of naming emperors and members of their family Constantine has been a constant source of confusion for numismatists and historians. Although scholars have long accepted that there were eleven of that name, a closer look reveals that there were actually twenty two Constantines, including children and relatives who never held independent power. Eliminating those would reduce the list to fourteen who actually reigned, but it seems unlikely that the accepted practice can be changed without introducing more confusion.Resume. — L'habitude byzantine de nommer Constantin les empereurs et les membres de leur famille a été une source permanente de confusion pour les numismates et les historiens. Bien que les érudits aient longtemps accepté l'idée qu'il y avait onze personnages ayant porté ce nom, un examen plus approfondi montre qu'il y eut en fait vingt-deux Constantins, en incluant enfants et parents qui n'exercèrent pas le pouvoir de manière indépendante. Les éliminer réduit la liste à quatorze personnages qui régnèrent effectivement, mais il paraît peu probable que la pratique actuelle puisse être modifiée sans augmenter le risque de confusion.Foss Clive. Emperors named Constantine. In: Revue numismatique, 6e série - Tome 161, année 2005 pp. 93-102