68 research outputs found
A near infrared frequency comb for Y+J band astronomical spectroscopy
Radial velocity (RV) surveys supported by high precision wavelength
references (notably ThAr lamps and I2 cells) have successfully identified
hundreds of exoplanets; however, as the search for exoplanets moves to cooler,
lower mass stars, the optimum wave band for observation for these objects moves
into the near infrared (NIR) and new wavelength standards are required. To
address this need we are following up our successful deployment of an H
band(1.45-1.7{\mu}m) laser frequency comb based wavelength reference with a
comb working in the Y and J bands (0.98-1.3{\mu}m). This comb will be optimized
for use with a 50,000 resolution NIR spectrograph such as the Penn State
Habitable Zone Planet Finder. We present design and performance details of the
current Y+J band comb.Comment: Submitted to SPIE, conference proceedings 845
Near field modal noise reduction using annealed optical fiber
Incomplete and unstable mode population has long complicated the application of optical fiber for transferring star and calibration light to high precision spectrographs. The need for improved precision calibrators in support of radial velocity planet surveys has led to the introduction of coherent wavelengths sources using single mode fibers that are then coupled into multi-mode fibers, further exacerbating this problem. We explore mode scrambling in annealed optical fiber with and without agitation, as compared to that obtained using octagonal fiber and using an integrating sphere. We observe improved scrambling with annealed fibers compared to conventional and octagonal fibers
Differential Deposition for Figure-Corrections in Grazing-Incidence X-Ray Optics
No abstract availabl
Improving X-ray Optics Through Differential Deposition
The differential deposition technique can in theory correct shell figures to approximate arcsecond value. We have received APRA funding and are building two custom system to demonstrate the technique on full shell and segmented optics. We hope to be able to demonstrate < 5 arcsec performance in < 2 years. To go beyond this, (arcsecond level) is very difficult to judge as we have not yet discovered the problems. May necessitate in-situ metrology, stress reduction investigations, correcting for gravity effects, correcting for temperature effects. Some of this will become obvious in early parts of the investigation
Conducting Science in Disasters: Recommendations from the NIEHS Working Group for Special IRB Considerations in the Review of Disaster Related Research.
Research involving human subjects after public health emergencies and disasters may pose ethical challenges. These challenges may include concerns about the vulnerability of prospective disaster research participants, increased research burden among disaster survivors approached by multiple research teams, and potentially reduced standards in the ethical review of research by institutional review boards (IRBs) due to the rush to enter the disaster field. The NIEHS Best Practices Working Group for Special IRB Considerations in the Review of Disaster Related Research was formed to identify and address ethical and regulatory challenges associated with the review of disaster research. The working group consists of a diverse collection of disaster research stakeholders across a broad spectrum of disciplines. The working group convened in July 2016 to identify recommendations that are instrumental in preparing IRBs to review protocols related to public health emergencies and disasters. The meeting included formative didactic presentations and facilitated breakout discussions using disaster-related case studies. Major thematic elements from these discussions were collected and documented into 15 working group recommendations, summarized in this article, that address topics such as IRB disaster preparedness activities, informed consent, vulnerable populations, confidentiality, participant burden, disaster research response integration and training, IRB roles/responsibilities, community engagement, and dissemination of disaster research results. https://doi.org/10.1289/EHP237
Supine posture changes lung volumes and increases ventilation heterogeneity in cystic fibrosis
INTRODUCTION: Lung Clearance Index (LCI) is recognised as an early marker of cystic fibrosis (CF) lung disease. The effect of posture on LCI however is important when considering longitudinal measurements from infancy and when comparing LCI to imaging studies. METHODS: 35 children with CF and 28 healthy controls (HC) were assessed. Multiple breath washout (MBW) was performed both sitting and supine in triplicate and analysed for LCI, Scond, Sacin, and lung volumes. These values were also corrected for the Fowler dead-space to create 'alveolar' indices. RESULTS: From sitting to supine there was a significant increase in LCI and a significant decrease in FRC for both CF and HC (p<0.01). LCI, when adjusted to estimate 'alveolar' LCI (LCIalv), increased the magnitude of change with posture for both LCIalv and FRCalv in both groups, with a greater effect of change in lung volume in HC compared with children with CF. The % change in LCIalv for all subjects correlated significantly with lung volume % changes, most notably tidal volume/functional residual capacity (Vtalv/FRCalv (r = 0.54,p<0.001)). CONCLUSION: There is a significant increase in LCI from sitting to supine, which we believe to be in part due to changes in lung volume and also increasing ventilation heterogeneity related to posture. This may have implications in longitudinal measurements from infancy to older childhood and for studies comparing supine imaging methods to LCI
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
Stellar Spectroscopy in the Near-infrared with a Laser Frequency Comb
The discovery and characterization of exoplanets around nearby stars is
driven by profound scientific questions about the uniqueness of Earth and our
Solar System, and the conditions under which life could exist elsewhere in our
Galaxy. Doppler spectroscopy, or the radial velocity (RV) technique, has been
used extensively to identify hundreds of exoplanets, but with notable
challenges in detecting terrestrial mass planets orbiting within habitable
zones. We describe infrared RV spectroscopy at the 10 m Hobby-Eberly telescope
that leverages a 30 GHz electro-optic laser frequency comb with nanophotonic
supercontinuum to calibrate the Habitable Zone Planet Finder spectrograph.
Demonstrated instrument precision <10 cm/s and stellar RVs approaching 1 m/s
open the path to discovery and confirmation of habitable zone planets around
M-dwarfs, the most ubiquitous type of stars in our Galaxy
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