168 research outputs found
Simulation of sub-millimetre atmospheric spectra for characterizing potential ground-based remote sensing observations
The sub-millimetre is an understudied region of the Earth's atmospheric electromagnetic spectrum. Prior technological gaps and relatively high opacity due to the prevalence of rotational water vapour lines at these wavelengths have slowed progress from a ground-based remote sensing perspective; however, emerging superconducting detector technologies in the fields of astronomy offer the potential to address key atmospheric science challenges with new instrumental methods. A site study, with a focus on the polar regions, is performed to assess theoretical feasibility by simulating the downwelling clear-sky sub-millimetre spectrum from 30 mm (10 GHz) to 150 μm (2000 GHz) at six locations under annual mean, summer, winter, daytime, nighttime and low humidity conditions. Vertical profiles of temperature, pressure and 28 atmospheric gases are constructed by combining radiosonde, meteorological reanalysis, and atmospheric chemistry model data. The sensitivity of the simulated spectra to the choice of water vapour continuum model and spectroscopic line database is explored. For the atmospheric trace species hypobromous acid (HOBr), hydrogen bromide (HBr), perhydroxyl radical (HO2) and nitrous oxide (N2O) the emission lines producing the largest change in brightness temperature are identified. Signal strengths, centre frequencies, bandwidths, estimated minimum integration times and maximum receiver noise temperatures are determined for all cases. HOBr, HBr and HO2 produce brightness temperature peaks in the mK to K range, whereas the N2O peaks are in the K range. The optimal sub-millimetre remote sensing lines for the four species are shown to vary significantly between location and scenario, strengthening the case for future hyperspectral instruments that measure over a broad wavelength range. The techniques presented here provide a framework that can be applied to additional species of interest and taken forward to simulate retrievals and guide the design of future sub-millimetre instruments
CLOVER - A new instrument for measuring the B-mode polarization of the CMB
We describe the design and expected performance of Clover, a new instrument
designed to measure the B-mode polarization of the cosmic microwave background.
The proposed instrument will comprise three independent telescopes operating at
90, 150 and 220 GHz and is planned to be sited at Dome C, Antarctica. Each
telescope will feed a focal plane array of 128 background-limited detectors and
will measure polarized signals over angular multipoles 20 < l < 1000. The
unique design of the telescope and careful control of systematics should enable
the B-mode signature of gravitational waves to be measured to a
lensing-confusion-limited tensor-to-scalar ratio r~0.005.Comment: 4 pages, 5 figures. To appear in the proceedings of the XXXVIXth
Rencontres de Moriond "Exploring the Universe
Intoxicants and the invention of 'consumption'
In 1600 the word ‘consumption’ was a term of medical pathology describing the ‘wasting, petrification of things’. By 1700 it was also a term of economic discourse: ‘In commodities, the value rises as its quantity is less and vent greater, which depends upon it being preferred in its consumption’. The article traces the emergence of this key category of economic analysis to debates over the economy in the 1620s and subsequent disputes over the excise tax, showing how ‘consumption’ was an early term in the developing lexicon of political economy. In so doing the article demonstrates the important role of ‘intoxicants’ – i.e. addictive and intoxicating commodities like alcohols and tobaccos – in shaping these early meanings and uses of ‘consumption’. It outlines the discursive importance of intoxicants, both as the foci for discussions of ‘superfluous’ and ‘necessary’ consumption and the target of legislation on consumption. And it argues that while these discussions had an ideological dimension, or dimensions, they were also responses to material increases in the volume and diversity of intoxicants in early seventeenth-century England. By way of conclusion the article suggests the significance of the Low Countries as a point of reference for English writers, as well as a more capacious and semantically sensitive approach to changes in early-modern consumption practices
SWIPE: a bolometric polarimeter for the Large-Scale Polarization Explorer
The balloon-borne LSPE mission is optimized to measure the linear
polarization of the Cosmic Microwave Background at large angular scales. The
Short Wavelength Instrument for the Polarization Explorer (SWIPE) is composed
of 3 arrays of multi-mode bolometers cooled at 0.3K, with optical components
and filters cryogenically cooled below 4K to reduce the background on the
detectors. Polarimetry is achieved by means of large rotating half-wave plates
and wire-grid polarizers in front of the arrays. The polarization modulator is
the first component of the optical chain, reducing significantly the effect of
instrumental polarization. In SWIPE we trade angular resolution for
sensitivity. The diameter of the entrance pupil of the refractive telescope is
45 cm, while the field optics is optimized to collect tens of modes for each
detector, thus boosting the absorbed power. This approach results in a FWHM
resolution of 1.8, 1.5, 1.2 degrees at 95, 145, 245 GHz respectively. The
expected performance of the three channels is limited by photon noise,
resulting in a final sensitivity around 0.1-0.2 uK per beam, for a 13 days
survey covering 25% of the sky.Comment: In press. Copyright 2012 Society of Photo-Optical Instrumentation
Engineers. One print or electronic copy may be made for personal use only.
Systematic reproduction and distribution, duplication of any material in this
paper for a fee or for commercial purposes, or modification of the content of
the paper are prohibite
HARP/ACSIS: A submillimetre spectral imaging system on the James Clerk Maxwell Telescope
This paper describes a new Heterodyne Array Receiver Programme (HARP) and
Auto-Correlation Spectral Imaging System (ACSIS) that have recently been
installed and commissioned on the James Clerk Maxwell Telescope (JCMT). The
16-element focal-plane array receiver, operating in the submillimetre from 325
to 375 GHz, offers high (three-dimensional) mapping speeds, along with
significant improvements over single-detector counterparts in calibration and
image quality. Receiver temperatures are 120 K across the whole band and
system temperatures of 300K are reached routinely under good weather
conditions. The system includes a single-sideband filter so these are SSB
figures. Used in conjunction with ACSIS, the system can produce large-scale
maps rapidly, in one or more frequency settings, at high spatial and spectral
resolution. Fully-sampled maps of size 1 square degree can be observed in under
1 hour.
The scientific need for array receivers arises from the requirement for
programmes to study samples of objects of statistically significant size, in
large-scale unbiased surveys of galactic and extra-galactic regions. Along with
morphological information, the new spectral imaging system can be used to study
the physical and chemical properties of regions of interest. Its
three-dimensional imaging capabilities are critical for research into
turbulence and dynamics. In addition, HARP/ACSIS will provide highly
complementary science programmes to wide-field continuum studies, and produce
the essential preparatory work for submillimetre interferometers such as the
SMA and ALMA.Comment: MNRAS Accepted 2009 July 2. 18 pages, 25 figures and 6 table
The Large-Scale Polarization Explorer (LSPE)
The LSPE is a balloon-borne mission aimed at measuring the polarization of
the Cosmic Microwave Background (CMB) at large angular scales, and in
particular to constrain the curl component of CMB polarization (B-modes)
produced by tensor perturbations generated during cosmic inflation, in the very
early universe. Its primary target is to improve the limit on the ratio of
tensor to scalar perturbations amplitudes down to r = 0.03, at 99.7%
confidence. A second target is to produce wide maps of foreground polarization
generated in our Galaxy by synchrotron emission and interstellar dust emission.
These will be important to map Galactic magnetic fields and to study the
properties of ionized gas and of diffuse interstellar dust in our Galaxy. The
mission is optimized for large angular scales, with coarse angular resolution
(around 1.5 degrees FWHM), and wide sky coverage (25% of the sky). The payload
will fly in a circumpolar long duration balloon mission during the polar night.
Using the Earth as a giant solar shield, the instrument will spin in azimuth,
observing a large fraction of the northern sky. The payload will host two
instruments. An array of coherent polarimeters using cryogenic HEMT amplifiers
will survey the sky at 43 and 90 GHz. An array of bolometric polarimeters,
using large throughput multi-mode bolometers and rotating Half Wave Plates
(HWP), will survey the same sky region in three bands at 95, 145 and 245 GHz.
The wide frequency coverage will allow optimal control of the polarized
foregrounds, with comparable angular resolution at all frequencies.Comment: In press. Copyright 2012 Society of Photo-Optical Instrumentation
Engineers. One print or electronic copy may be made for personal use only.
Systematic reproduction and distribution, duplication of any material in this
paper for a fee or for commercial purposes, or modification of the content of
the paper are prohibite
Multimode horn antennas for far-infrared astronomy
Multi-mode horns combined with bolometric or incoherent detectors are finding application in astronomical receivers for which partially coherent operation can provide increased throughput and thus sensitivity. This is advantageous when observing faint sources, especially if diffraction limited resolution is not required, or if the horn beam is truncated by a cold stop in the optical train. We discuss how such horns can be simulated and present examples from receiver instrumentation on the Planck and SPICA space telescopes
COrE (Cosmic Origins Explorer) A White Paper
COrE (Cosmic Origins Explorer) is a fourth-generation full-sky,
microwave-band satellite recently proposed to ESA within Cosmic Vision
2015-2025. COrE will provide maps of the microwave sky in polarization and
temperature in 15 frequency bands, ranging from 45 GHz to 795 GHz, with an
angular resolution ranging from 23 arcmin (45 GHz) and 1.3 arcmin (795 GHz) and
sensitivities roughly 10 to 30 times better than PLANCK (depending on the
frequency channel). The COrE mission will lead to breakthrough science in a
wide range of areas, ranging from primordial cosmology to galactic and
extragalactic science. COrE is designed to detect the primordial gravitational
waves generated during the epoch of cosmic inflation at more than
for . It will also measure the CMB gravitational lensing
deflection power spectrum to the cosmic variance limit on all linear scales,
allowing us to probe absolute neutrino masses better than laboratory
experiments and down to plausible values suggested by the neutrino oscillation
data. COrE will also search for primordial non-Gaussianity with significant
improvements over Planck in its ability to constrain the shape (and amplitude)
of non-Gaussianity. In the areas of galactic and extragalactic science, in its
highest frequency channels COrE will provide maps of the galactic polarized
dust emission allowing us to map the galactic magnetic field in areas of
diffuse emission not otherwise accessible to probe the initial conditions for
star formation. COrE will also map the galactic synchrotron emission thirty
times better than PLANCK. This White Paper reviews the COrE science program,
our simulations on foreground subtraction, and the proposed instrumental
configuration.Comment: 90 pages Latex 15 figures (revised 28 April 2011, references added,
minor errors corrected
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A study protocol for a randomised feasibility study Comparing Urolift and Standard Transurethral resection of prostate Ahead of Radiotherapy in men with urinary symptoms secondary to prostate enlargement in Southwest London and North Cumbria (COSTAR)
Introduction
Patients undergoing prostate radiotherapy with an enlarged prostate can have short and long term urinary complications. Currently, Transurethral resection of the prostate (TURP) is the mainstay surgical intervention for men with urinary symptoms due to an enlarged prostate prior to radiotherapy. UroLift (NeoTract Inc., Pleasanton, CA USA) is a recent minimally invasive alternative, widely used in benign disease but is untested in men with prostate cancer.
Methods and Analysis
A multi-centre, two-arm study designed in collaboration with a Patient Reference Group to assess the feasibility of randomising men with prostate cancer and co-existing urinary symptoms due to prostate enlargement to TURP or UroLift ahead of radiotherapy. 45 patients will be enrolled and randomised (1:1) using a computer-generated programme to TURP or UroLift.
Recruitment and retention will be assessed over a 12-month period. Information on clinical outcomes, Adverse Events, and costs will be collected. Clinical outcomes and Patient Reported Outcome Measures (PROMs) will be measured at baseline, six-weeks post-intervention and three months following radiotherapy. A further 12 in-depth interviews will be conducted with a subset of patients to assess acceptability using the Theoretical Framework of Acceptability. Descriptive analysis on all outcomes will be performed using Stata (StataCorp 2021).
Ethics and Dissemination
The trial has been approved by the Research Ethics Committee (REC) NHS Health Research Authority (HRA) and Health and Care Research Wales (HCRW). The results will be published in peer-reviewed journals, presented at national meetings and disseminated to patients via social media, charity and hospital websites
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