486 research outputs found
Small (<1Â cm) incidental echogenic renal cortical nodules: chemical shift MRI outperforms CT for confirmatory diagnosis of angiomyolipoma (AML)
Characterization of entangling properties of quantum measurement via two-mode quantum detector tomography using coherent state probes
Entangled measurement is a crucial tool in quantum technology. We propose a
new entanglement measure of multi-mode detection, which estimates the amount of
entanglement that can be created in a measurement. To illustrate the proposed
measure, we perform quantum tomography of a two-mode detector that is comprised
of two superconducting nanowire single photon detectors. Our method utilizes
coherent states as probe states, which can be easily prepared with accuracy.
Our work shows that a separable state such as a coherent state is enough to
characterize a potentially entangled detector. We investigate the entangling
capability of the detector in various settings. Our proposed measure verifies
that the detector makes an entangled measurement under certain conditions, and
reveals the nature of the entangling properties of the detector. Since the
precise characterization of a detector is essential for applications in quantum
information technology, the experimental reconstruction of detector properties
along with the proposed measure will be key features in future quantum
information processing.Comment: 18 pages, 6 figure
Relative pointing offset analysis of calibration targets with repeated observations with Herschel-SPIRE Fourier-Transform Spectrometer
We present a method to derive the relative pointing offsets for SPIRE
Fourier-Transform Spectrometer (FTS) solar system object (SSO) calibration
targets, which were observed regularly throughout the Herschel mission. We
construct ratios of the spectra for all observations of a given source with
respect to a reference. The reference observation is selected iteratively to be
the one with the highest observed continuum. Assuming that any pointing offset
leads to an overall shift of the continuum level, then these ratios represent
the relative flux loss due to mispointing. The mispointing effects are more
pronounced for a smaller beam, so we consider only the FTS short wavelength
array (SSW, 958-1546 GHz) to derive a pointing correction. We obtain the
relative pointing offset by comparing the ratio to a grid of expected losses
for a model source at different distances from the centre of the beam, under
the assumption that the SSW FTS beam can be well approximated by a Gaussian. In
order to avoid dependency on the point source flux conversion, which uses a
particular observation of Uranus, we use extended source flux calibrated
spectra to construct the ratios for the SSOs. In order to account for continuum
variability, due to the changing distance from the Herschel telescope, the SSO
ratios are normalised by the expected model ratios for the corresponding
observing epoch. We confirm the accuracy of the derived pointing offset by
comparing the results with a number of control observations, where the actual
pointing of Herschel is known with good precision. Using the method we derived
pointing offsets for repeated observations of Uranus (including observations
centred on off-axis detectors), Neptune, Ceres and NGC7027. The results are
used to validate and improve the point-source flux calibration of the FTS.Comment: 17 pages, 19 figures, accepted for publication in Experimental
Astronom
Herschel SPIRE FTS Relative Spectral Response Calibration
Herschel/SPIRE Fourier transform spectrometer (FTS) observations contain
emission from both the Herschel Telescope and the SPIRE Instrument itself, both
of which are typically orders of magnitude greater than the emission from the
astronomical source, and must be removed in order to recover the source
spectrum. The effects of the Herschel Telescope and the SPIRE Instrument are
removed during data reduction using relative spectral response calibration
curves and emission models. We present the evolution of the methods used to
derive the relative spectral response calibration curves for the SPIRE FTS. The
relationship between the calibration curves and the ultimate sensitivity of
calibrated SPIRE FTS data is discussed and the results from the derivation
methods are compared. These comparisons show that the latest derivation methods
result in calibration curves that impart a factor of between 2 and 100 less
noise to the overall error budget, which results in calibrated spectra for
individual observations whose noise is reduced by a factor of 2-3, with a gain
in the overall spectral sensitivity of 23% and 21% for the two detector bands,
respectively.Comment: 15 pages, 13 figures, accepted for publication in Experimental
Astronom
Herschel SPIRE Fourier Transform Spectrometer: Calibration of its Bright-source Mode
The Fourier Transform Spectrometer (FTS) of the Spectral and Photometric
Imaging REceiver (SPIRE) on board the ESA Herschel Space Observatory has two
detector setting modes: (a) a nominal mode, which is optimized for observing
moderately bright to faint astronomical targets, and (b) a bright-source mode
recommended for sources significantly brighter than 500 Jy, within the SPIRE
FTS bandwidth of 446.7-1544 GHz (or 194-671 microns in wavelength), which
employs a reduced detector responsivity and out-of-phase analog signal
amplifier/demodulator. We address in detail the calibration issues unique to
the bright-source mode, describe the integration of the bright-mode data
processing into the existing pipeline for the nominal mode, and show that the
flux calibration accuracy of the bright-source mode is generally within 2% of
that of the nominal mode, and that the bright-source mode is 3 to 4 times less
sensitive than the nominal mode.Comment: 15 pages, 16 figures, accepted for publication in Experimental
Astronom
Recommended from our members
NMDA receptor antagonists and pain relief: A meta-analysis of experimental trials
OBJECTIVES:
We conducted a meta-analysis of controlled trials that used experimental models of acute pain and hyperalgesia to examine the analgesic effects of N-methyl-D-aspartate receptor (NMDAR) antagonists.
METHODS:
Six major databases were systematically searched (to 03/2018) for studies using human evoked pain models to compare NMDAR antagonists with no-intervention controls. Pain outcome data were analyzed with random-effects meta-analysis.
RESULTS:
Searches identified 70 eligible trials (N=1069). Meta-analysis found that low-dose ketamine (<1 mg/kg) produced a decrease in the size of hyperalgesic area (Standardized Mean Difference=0.54, CI95[0.34, 0.74], p<.001), and a 1.2-point decrease (CI95[0.88, 1.44], p<.001) in pain ratings from 4.6 to 3.4 on a 0-10 scale (a 26% reduction). Similar analgesia was observed for acute and hyperalgesic models and was constant across the dosing range (0.03-1.00 mg/kg). Moderate-high variability in effect size was observed and mild side effects (e.g. sedation, sensory disturbance) were common. No effects of dextromethorphan were found.
CONCLUSIONS:
Findings provide robust evidence for analgesic and anti-hyperalgesic effects of ketamine, supporting its utility for acute and chronic pain management. However, pain relief was modest, suggesting ketamine may potentially be most useful when opioids are contraindicated, rapid analgesia is required or for pain resistant to conventional medication
Varied effects of algal symbionts on transcription factor NF-ÎșB in a sea anemone and a coral: possible roles in symbiosis and thermotolerance
Many cnidarians, including the reef-building corals, undergo symbiotic mutualisms with photosynthetic dinoflagellate algae of the family Symbiodiniaceae. These partnerships are sensitive to temperature extremes, which cause symbiont loss and increased coral mortality. Previous studies have implicated host immunity and specifically immunity transcription factor NF-ÎșB as having a role in the maintenance of the cnidarian-algal symbiosis. Here we have further investigated a possible role for NF-ÎșB in establishment and loss of symbiosis in various strains of the anemone Exaiptasia (Aiptasia) and in the coral Pocillopora damicornis. Our results show that NF-ÎșB expression is reduced in Aiptasia larvae and adults that host certain algae strains. Treatment of Aiptasia larvae with a known symbiosis-promoting cytokine, transforming growth factor ÎČ, also led to decreased NF-ÎșB expression. We also show that aposymbiotic Aiptasia (with high NF-ÎșB expression) have increased survival following infection with the pathogenic bacterium Serratia marcescens as compared to symbiotic Aiptasia (low NF-ÎșB expression). Furthermore, a P. damicornis coral colony hosting Durusdinium spp. (formerly clade D) symbionts had higher basal NF-ÎșB expression and decreased heat-induced bleaching as compared to two individuals hosting Cladocopium spp. (formerly clade C) symbionts. Lastly, genome-wide gene expression profiling and genomic promoter analysis identified putative NF-ÎșB target genes that may be involved in thermal bleaching, symbiont maintenance, and/or immune protection in P. damicornis. Our results provide further support for the hypothesis that modulation of NF-ÎșB and immunity plays a role in some, but perhaps not all, cnidarian-Symbiodiniaceae partnerships as well as in resistance to pathogens and bleaching.Accepted manuscrip
Herschel SPIRE FTS Spectral Mapping Calibration
The Herschel SPIRE Fourier transform spectrometer (FTS) performs spectral
imaging in the 447-1546 GHz band. It can observe in three spatial sampling
modes: sparse mode, with a single pointing on sky, or intermediate or full
modes with 1 and 1/2 beam spacing, respectively. In this paper, we investigate
the uncertainty and repeatability for fully sampled FTS mapping observations.
The repeatability is characterised using nine observations of the Orion Bar.
Metrics are derived based on the ratio of the measured intensity in each
observation compared to that in the combined spectral cube from all
observations. The mean relative deviation is determined to be within 2%, and
the pixel-by-pixel scatter is ~7%. The scatter increases towards the edges of
the maps. The uncertainty in the frequency scale is also studied, and the
spread in the line centre velocity across the maps is found to be ~15 km/s.
Other causes of uncertainty are also discussed including the effect of pointing
and the additive uncertainty in the continuum.Comment: 12 pages, 9 figures, accepted for publication in Experimental
Astronom
Seeking support after hospitalisation for injury: a nested qualitative study of the role of primary care
Background: In the UK, studies suggest that the transition from hospital to home after an injury can be a difficult time and many patients report feeling inadequately prepared. Patients often use primary care services after hospital discharge. These consultations provide opportunities to consider problems that patients experience and to facilitate recovery. Little is known, however, about how patients and service providers view care after hospital discharge and the role played by primary care services, specifically GPs. Aim: To identify good practice and unmet needs in respect of post-discharge support for injured patients. Design and setting: Qualitative study using semi-structured interviews at four sites (Bristol, Leicester/ Loughborough, Nottingham, and Surrey). Method: Qualitative interviews with 40 service providers and 45 hospitalised injured patients. Results: Although there were examples of well-managed hospital discharges, many patients felt they were not provided with the information they needed about their injury, what to expect in terms of recovery, pain control, return to work, psychological problems, and services to help meet their needs. They also described difficulty accessing services such as physiotherapy or counselling. Service providers identified problems with communication between secondary and primary care, lack of access to physiotherapy, poor communication about other services that may help patients, GP service and resource constraints, and difficulties in providing information to patients concerning likely prognosis. Conclusion: Discharge from hospital after an injury can be problematic for patients. Changes in both secondary and primary care are required to resolve this problem
The effectiveness of hypnosis for pain relief: A systematic review and meta-analysis of 85 controlled experimental trials
The current meta-analysis aimed to quantify the effectiveness of hypnosis for reducing pain and identify factors that influence efficacy. Six major databases were systematically searched for trials comparing hypnotic inductions with no- intervention control conditions on pain ratings, threshold and tolerance using experimentally-evoked pain models in healthy participants. Eighty-five eligible studies (primarily crossover trials) were identified, consisting of 3632 participants (hypnosis n=2892, control n=2646). Random effects meta-analysis found analgesic effects of hypnosis for all pain outcomes (g=0.54-0.76, pâs<.001). Efficacy was strongly influenced by hypnotic suggestibility and use of direct analgesic suggestion. Specifically, optimal pain relief was obtained for hypnosis with direct analgesic suggestion administered to high and medium suggestibles, who respectively demonstrated 42% (p<.001) and 29% (p<.001) clinically meaningful reductions in pain. Minimal benefits were found for low suggestibles. These findings suggest that hypnotic intervention can deliver meaningful pain relief for most people and therefore may be an effective and safe alternative to pharmaceutical intervention. High quality clinical data is, however, needed to establish generalisability in chronic pain populations
- âŠ