Feasibility of transit photometry of nearby debris discs

Dust in debris discs is constantly replenished by collisions between larger objects. In this paper, we investigate a method to detect these collisions. We generate models based on recent results on the Fomalhaut debris disc, where we simulate a background star transiting behind the disc, due to the proper motion of Fomalhaut. By simulating the expanding dust clouds caused by the collisions in the debris disc, we investigate whether it is possible to observe changes in the brightness of the background star. We conclude that in the case of the Fomalhaut debris disc, changes in the optical depth can be observed, with values of the optical depth ranging from $10^{-0.5}$ for the densest dust clouds to $10^{-8}$ for the most diffuse clouds with respect to the background optical depth of $\sim1.2\times10^{-3}$.Comment: 19 pages, 15 figures, accepted for publication in MNRA

Optimized Principal Component Analysis on Coronagraphic Images of the Fomalhaut System

We present the results of a study to optimize the principal component analysis (PCA) algorithm for planet detection, a new algorithm complementing ADI and LOCI for increasing the contrast achievable next to a bright star. The stellar PSF is constructed by removing linear combinations of principal components, allowing the flux from an extrasolar planet to shine through. The number of principal components used determines how well the stellar PSF is globally modelled. Using more principal components may decrease the number of speckles in the final image, but also increases the background noise. We apply PCA to Fomalhaut VLT NaCo images acquired at 4.05 micron with an apodized phase plate. We do not detect any companions, with a model dependent upper mass limit of 13-18 M_Jup from 4-10 AU. PCA achieves greater sensitivity than the LOCI algorithm for the Fomalhaut coronagraphic data by up to 1 magnitude. We make several adaptations to the PCA code and determine which of these prove the most effective at maximizing the signal-to-noise from a planet very close to its parent star. We demonstrate that optimizing the number of principal components used in PCA proves most effective for pulling out a planet signal.Comment: Accepted for publication in ApJ, 7 pages, 9 figure

Searching for gas giant planets on Solar System scales - A NACO/APP L'-band survey of A- and F-type Main Sequence stars

We report the results of a direct imaging survey of A- and F-type main sequence stars searching for giant planets. A/F stars are often the targets of surveys, as they are thought to have more massive giant planets relative to solar-type stars. However, most imaging is only sensitive to orbital separations $>$30 AU, where it has been demonstrated that giant planets are rare. In this survey, we take advantage of the high-contrast capabilities of the Apodizing Phase Plate coronagraph on NACO at the Very Large Telescope. Combined with optimized principal component analysis post-processing, we are sensitive to planetary-mass companions (2 to 12 $M_{\rm Jup}$) at Solar System scales ($\leq$30 AU). We obtained data on 13 stars in L'-band and detected one new companion as part of this survey: an M$6.0\pm0.5$ dwarf companion around HD 984. We re-detect low-mass companions around HD 12894 and HD 20385, both reported shortly after the completion of this survey. We use Monte Carlo simulations to determine new constraints on the low-mass ($<$80 $M_{\rm Jup}$) companion frequency, as a function of mass and separation. Assuming solar-type planet mass and separation distributions, normalized to the planet frequency appropriate for A-stars, and the observed companion mass-ratio distribution for stellar companions extrapolated to planetary masses, we derive a truncation radius for the planetary mass companion surface density of $<$135 AU at 95% confidence.Comment: Accepted for publication in MNRAS, 8 pages, 4 figure

Compression After Impact Testing of Sandwich Structures Using the Four Point Bend Test

For many composite laminated structures, the design is driven by data obtained from Compression after Impact (CAI) testing. There currently is no standard for CAI testing of sandwich structures although there is one for solid laminates of a certain thickness and lay-up configuration. Most sandwich CAI testing has followed the basic technique of this standard where the loaded ends are precision machined and placed between two platens and compressed until failure. If little or no damage is present during the compression tests, the loaded ends may need to be potted to prevent end brooming. By putting a sandwich beam in a four point bend configuration, the region between the inner supports is put under a compressive load and a sandwich laminate with damage can be tested in this manner without the need for precision machining. Also, specimens with no damage can be taken to failure so direct comparisons between damaged and undamaged strength can be made. Data is presented that demonstrates the four point bend CAI test and is compared with end loaded compression tests of the same sandwich structure

Confirmation of the planet around HD 95086 by direct imaging

VLT/NaCo angular differential imaging at L' (3.8 microns) revealed a probable giant planet comoving with the young and early-type HD 95086 also known to harbor an extended debris disk. The discovery was based on the proper motion analysis of two datasets spanning 15 months. However, the second dataset suffered from bad atmospheric conditions, which limited the significance of the redetection at the 3 sigma level. In this Letter, we report new VLT/NaCo observations of HD 95086 obtained on 2013 June 26-27 at L' to recover the planet candidate. We unambiguously redetect the companion HD 95086 b with multiple independent pipelines at a signal-to-noise ratio greater than or equal to 5. Combined with previously reported measurements, our astrometry decisively shows that the planet is comoving with HD 95086 and inconsistent with a background object. With a revised mass of 5 pm 2 Jupiter masses, estimated from its L' photometry and "hot-start" models at 17 pm 4 Myr, HD 95086 b becomes a new benchmark for further physical and orbital characterization of young giant planets.Comment: accepted for publication to AP

Steady-State Probe-Partitioning FRET: A Simple and Robust Tool for the Study of Membrane Phase Behavior

An experimental strategy has been developed specifically for the study of composition-dependent phase behavior in multi-component artificial membranes. The strategy is based on steady-state measurements of fluorescence resonance energy transfer between freely diffusing membrane probe populations, and it is well suited for the rapid generation of large data sets. Presented in this paper are the basic principles that guide the experiment's design, the derivation of an underlying mathematical model that serves to interpret the data, and experimental results that confirm the model's predictive power.Comment: 7 pages, 4 figure

Does exercise influence burn-induced inflammation: A cross-over randomised controlled feasibility trial

Background Burn injuries trigger a greater and more persistent inflammatory response than other trauma cases. Exercise has been shown to positively influence inflammation in healthy and diseased populations, however little is known about the latent effect of exercise on chronic inflammation in burn injured patients. The aims of the pilot study were to assess the feasibility of implementing a long duration exercise training program, in burn injured individuals including learnings associated with conducting a clinical trial in COVID-19 pandemic. Methods Fifteen participants with a burn injury between 5–20% total body surface area acquired greater than a year ago were randomised in a within-subject designed study, into one of two conditions, exercise–control or control–exercise. The exercise condition consisted of six weeks of resistance and cardiovascular exercises, completed remotely or supervised in a hospital gym. A comprehensive outcome measurement was completed at the initial, mid and end point of each exercise and control condition. To determine the success of implementation, the feasibility indicator for the data completeness across the comprehensive outcome battery was set at 80%. Results Half (49%) of eligible participants in the timeframe, were recruited and commenced the study. Six participants withdrew prior to completion and a total of 15 participants completed the study. Eight participants were randomised to the exercise-control and seven to the control exercise group. Five participants trained remotely and seven did supervised training. Three participants completed a mix of both supervised and remote training initiated due to COVID restrictions. Outcome measures were completed on 97% of protocolised occasions and 100% of participants completed the exercise training. Conclusions Conducting a long duration exercise training study on burn injured individuals is feasible using the described methods. The knowledge gained helps improve the methodology in larger-scale projects. Insights into the impact of COVID-19 on this clinical trial and success enhancing adaptations for the researcher, research practice and the participant, are presented

Discovery of a Low-Mass Companion to the F7V star HD 984

We report the discovery of a low-mass companion to the nearby (d = 47 pc) F7V star HD 984. The companion is detected 0.19" away from its host star in the L' band with the Apodizing Phase Plate on NaCo/VLT and was recovered by L'-band non-coronagraphic imaging data taken a few days later. We confirm the companion is co-moving with the star with SINFONI integral field spectrograph H+K data. We present the first published data obtained with SINFONI in pupil-tracking mode. HD 984 has been argued to be a kinematic member of the 30 Myr-old Columba group, and its HR diagram position is not altogether inconsistent with being a ZAMS star of this age. By consolidating different age indicators, including isochronal age, coronal X-ray emission, and stellar rotation, we independently estimate a main sequence age of 115$\pm$85 Myr (95% CL) which does not rely on this kinematic association. The mass of directly imaged companions are usually inferred from theoretical evolutionary tracks, which are highly dependent on the age of the star. Based on the age extrema, we demonstrate that with our photometric data alone, the companion's mass is highly uncertain: between 33 and 96 M$_{\rm Jup}$ (0.03-0.09 M$_{\odot}$) using the COND evolutionary models. We compare the companion's SINFONI spectrum with field dwarf spectra to break this degeneracy. Based on the slope and shape of the spectrum in the H-band, we conclude that the companion is an M$6.0\pm0.5$ dwarf. The age of the system is not further constrained by the companion, as M dwarfs are poorly fit on low-mass evolutionary tracks. This discovery emphasizes the importance of obtaining a spectrum to spectral type companions around F-stars.Comment: Accepted for publication in MNRAS, 10 pages, 5 figure

A Medium Resolution Near-Infrared Spectral Atlas of O and Early B Stars

We present intermediate resolution (R ~ 8,000 - 12,000) high signal-to-noise H- and K-band spectroscopy of a sample of 37 optically visible stars, ranging in spectral type from O3 to B3 and representing most luminosity classes. Spectra of this quality can be used to constrain the temperature, luminosity and general wind properties of OB stars, when used in conjunction with sophisticated atmospheric model codes. Most important is the need for moderately high resolutions (R > 5000) and very high signal-to-noise (S/N > 150) spectra for a meaningful profile analysis. When using near-infrared spectra for a classification system, moderately high signal-to-noise (S/N ~ 100) is still required, though the resolution can be relaxed to just a thousand or two. In the appendix we provide a set of very high quality near-infrared spectra of Brackett lines in six early-A dwarfs. These can be used to aid in the modeling and removal of such lines when early-A dwarfs are used for telluric spectroscopic standards.Comment: 12 pages, 3 tables, 14 figures. AASTex preprint style. To appear in ApJS, November 2005. All spectra are available by contacting M.M. Hanso