Wide-bandwidth, tunable, multiple-pulse-width optical delays using slow light in cesium vapor

We demonstrate an all-optical delay line in hot cesium vapor that tunably delays 275 ps input pulses up to 6.8 ns and 740 input ps pulses up to 59 ns (group index of approximately 200) with little pulse distortion. The delay is made tunable with a fast reconfiguration time (hundreds of ns) by optically pumping out of the atomic ground states.Comment: 4 pages, 6 figure

Patient Experiences of Recovery After Autologous Chondrocyte Implantation: A Qualitative Study

Context: The recovery process after autologous chondrocyte implantation (ACI) can be challenging for patients and clinicians alike due to significant functional limitations and a lengthy healing time. Understanding patients\u27 experiences during the recovery process may assist clinicians in providing more individualized care. Objective: To explore and describe patients\u27 experiences during the recovery process after ACI. Design: Qualitative study. Setting: Orthopaedic clinic. Patients or Other Participants: Participants from a single orthopaedic practice who had undergone ACI within the previous 12 months were purposefully selected. Data Collection and Analysis: Volunteers participated in 1-on-1 semistructured interviews to describe their recovery experiences after ACI. Data were analyzed using the process of horizontalization. Results: Seven patients (2 men, 5 women; age = 40.7 ± 7.5 years, time from surgery = 8.7 ± 4.2 months) participated. Four themes and 6 subthemes emerged from the data and suggested that the recovery process is a lengthy and emotional experience. Therapy provides optimism for the future but requires a collaborative effort among the patient, surgeon, rehabilitation provider, and patient\u27s caregiver(s). Furthermore, patients expressed frustration that their expectations for recovery did not match the reality of the process, including greater dependence on caregivers than expected. Conclusions: Patients\u27 expectations should be elicited before surgery and managed throughout the recovery process. Providing preoperative patient and caregiver education and encouraging preoperative rehabilitation can assist in managing expectations. Establishing realistic goals and expectations may improve rehabilitation adherence, encourage optimism for recovery, and improve outcomes in the long term

The virtual haptic back: A simulation for training in palpatory diagnosis

<p>Abstract</p> <p>Background</p> <p>Models and simulations are finding increased roles in medical education. The Virtual Haptic Back (VHB) is a virtual reality simulation of the mechanical properties of the human back designed as an aid to teaching clinical palpatory diagnosis.</p> <p>Methods</p> <p>Eighty-nine first year medical students of the Ohio University College of Osteopathic Medicine carried out six, 15-minute practice sessions with the VHB, plus tests before and after the sessions in order to monitor progress in identifying regions of simulated abnormal tissue compliance. Students palpated with two digits, fingers or thumbs, by placing them in gimbaled thimbles at the ends of PHANToM 3.0^®haptic interface arms. The interface simulated the contours and compliance of the back surface by the action of electric motors. The motors limited the compression of the virtual tissues induced by the palpating fingers, by generating counterforces. Users could see the position of their fingers with respect to the back on a video monitor just behind the plane of the haptic back. The abnormal region varied randomly among 12 locations between trials. During the practice sessions student users received immediate feedback following each trial, indicating either a correct choice or the actual location of the abnormality if an incorrect choice had been made. This allowed the user to feel the actual abnormality before going on to the next trial. Changes in accuracy, speed and Weber fraction across practice sessions were analyzed using a repeated measures analysis of variance.</p> <p>Results</p> <p>Students improved in accuracy and speed of diagnosis with practice. The smallest difference in simulated tissue compliance users were able to detect improved from 28% (SD = 9.5%) to 14% (SD = 4.4%) during the practice sessions while average detection time decreased from 39 (SD = 19.8) to 17 (SD = 11.7) seconds. When asked in anonymous evaluation questionnaires if they judged the VHB practice to be helpful to them in the clinical palpation and manual medicine laboratory, 41% said yes, 51% said maybe, and 8% said no.</p> <p>Conclusion</p> <p>The VHB has potential value as a teaching aid for students in the initial phases of learning palpatory diagnosis.</p

Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) onboard calibration system

The AVIRIS instrument uses an onboard calibration system to provide auxiliary calibration data. The system consist of a tungsten halogen cycle lamp imaged onto a fiber bundle through an eight position filter wheel. The fiber bundle illuminates the back side of the foreoptics shutter during a pre-run and post-run calibration sequence. The filter wheel contains two neutral density filters, five spectral filters and one blocked position. This paper reviews the general workings of the onboard calibrator system and discusses recent modifications

A Study of Carbon Features in Type Ia Supernova Spectra

One of the major differences between various explosion scenarios of Type Ia supernovae (SNe Ia) is the remaining amount of unburned (C+O) material and its velocity distribution within the expanding ejecta. While oxygen absorption features are not uncommon in the spectra of SNe Ia before maximum light, the presence of strong carbon absorption has been reported only in a minority of objects, typically during the pre-maximum phase. The reported low frequency of carbon detections may be due to low signal-to-noise data, low abundance of unburned material, line blending between C II 6580 and Si II 6355, ejecta temperature differences, asymmetrical distribution effects, or a combination of these. However, a survey of published pre-maximum spectra reveals that more SNe Ia than previously thought may exhibit C II 6580 absorption features and relics of line blending near 6300 Angstroms. Here we present new SN Ia observations where spectroscopic signatures of C II 6580 are detected, and investigate the presence of C II 6580 in the optical spectra of 19 SNe Ia using the parameterized spectrum synthesis code, SYNOW. Most of the objects in our sample that exhibit C II 6580 absorption features are of the low-velocity gradient subtype. Our study indicates that the morphology of carbon-rich regions is consistent with either a spherical distribution or a hemispheric asymmetry, supporting the recent idea that SN Ia diversity may be a result of off-center ignition coupled with observer line-of-sight effects.Comment: 10 papges, 9 figures, 3 table

Detection of Planetary and Stellar Companions to Neighboring Stars via a Combination of Radial Velocity and Direct Imaging Techniques

13 pages, 6 figures, 4 tables, accepted for publication in the Astronomical Journal (submitted 25 Feb 2019; accepted 28 April 2019). Machine readable tables and Posteriors from the RadVel fits are available here: http://stephenkane.net/rvfits.tarThe sensitivities of radial velocity (RV) surveys for exoplanet detection are extending to increasingly longer orbital periods, where companions with periods of several years are now being regularly discovered. Companions with orbital periods that exceed the duration of the survey manifest in the data as an incomplete orbit or linear trend, a feature that can either present as the sole detectable companion to the host star, or as an additional signal overlain on the signatures of previously discovered companion(s). A diagnostic that can confirm or constrain scenarios in which the trend is caused by an unseen stellar rather than planetary companion is the use of high-contrast imaging observations. Here, we present RV data from the Anglo-Australian Planet Search (AAPS) for 20 stars that show evidence of orbiting companions. Of these, six companions have resolved orbits, with three that lie in the planetary regime. Two of these (HD 92987b and HD 221420b) are new discoveries. Follow-up observations using the Differential Speckle Survey Instrument (DSSI) on the Gemini South telescope revealed that 5 of the 20 monitored companions are likely stellar in nature. We use the sensitivity of the AAPS and DSSI data to place constraints on the mass of the companions for the remaining systems. Our analysis shows that a planetary-mass companion provides the most likely self-consistent explanation of the data for many of the remaining systems.Peer reviewedFinal Accepted Versio

New calibration techniques for the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS)

Recent laboratory calibrations of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) include new methods for the characterization of the geometric, spectral, temporal and radiometric properties of the sensor. New techniques are desired in order to: (1) increase measurement accuracy and precision, (2) minimize measurement time and expense, (3) prototype new field and inflight calibration systems, (4) resolve measurement ambiguities, and (5) add new measurement dimensions. One of the common features of these new methods is the use of the full data collection and processing power of the AVIRIS instrument and data facility. This allows the collection of large amounts of calibration data in a short period of time and is well suited to modular data analysis routines