Narrow Pass-Band Optical Filters for Space-Borne Remote Sensing Applications

Optical characterisation of 532 nm, 200 pm passband and 1064 nm, I mn passband LkD filters after exposure to proton irradiation, temperature cycling and angle tuning

Leveraging OpenStack and Ceph for a Controlled-Access Data Cloud

While traditional HPC has and continues to satisfy most workflows, a new generation of researchers has emerged looking for sophisticated, scalable, on-demand, and self-service control of compute infrastructure in a cloud-like environment. Many also seek safe harbors to operate on or store sensitive and/or controlled-access data in a high capacity environment. To cater to these modern users, the Minnesota Supercomputing Institute designed and deployed Stratus, a locally-hosted cloud environment powered by the OpenStack platform, and backed by Ceph storage. The subscription-based service complements existing HPC systems by satisfying the following unmet needs of our users: a) on-demand availability of compute resources, b) long-running jobs (i.e., $> 30$ days), c) container-based computing with Docker, and d) adequate security controls to comply with controlled-access data requirements. This document provides an in-depth look at the design of Stratus with respect to security and compliance with the NIH's controlled-access data policy. Emphasis is placed on lessons learned while integrating OpenStack and Ceph features into a so-called "walled garden", and how those technologies influenced the security design. Many features of Stratus, including tiered secure storage with the introduction of a controlled-access data "cache", fault-tolerant live-migrations, and fully integrated two-factor authentication, depend on recent OpenStack and Ceph features.Comment: 7 pages, 5 figures, PEARC '18: Practice and Experience in Advanced Research Computing, July 22--26, 2018, Pittsburgh, PA, US

Fiber lasers and amplifiers for science and exploration at NASA Goddard Space Flight Center

We discuss present and near-term uses for high-power fiber lasers and amplifiers for NASA- specific applications including planetary topography and atmospheric spectroscopy. Fiber lasers and amplifiers offer numerous advantages for both near-term and future deployment of instruments on exploration and science remote sensing orbiting satellites. Ground-based and airborne systems provide an evolutionary path to space and a means for calibration and verification of space-borne systems. We present experimental progress on both the fiber transmitters and instrument prototypes for ongoing development efforts. These near-infrared instruments are laser sounders and lidars for measuring atmospheric carbon dioxide, oxygen, water vapor and methane and a pseudo-noise (PN) code laser ranging system. The associated fiber transmitters include high-power erbium, ytterbium, neodymium and Raman fiber amplifiers. In addition, we will discuss near-term fiber laser and amplifier requirements and programs for NASA free space optical communications, planetary topography and atmospheric spectroscopy

Effects of scan direction and orientation on mechanical properties of laser sintered polyamide-12

In order to understand the impact of layer-wise scanning direction in the Selective Laser Sintering process, test coupons were manufactured for mechanical testing from DuraForm™ Polyamide powder. The effects of laser energy density, varying between 0.003 and 0.024 J/mm2 were examined in test specimens rotated 90º through the Z axis. SLS machines do not always facilitate ‘cross-hatching’ of layers and therefore orientation has a major influence on part quality. When employed, the cross-hatching technique scans successive layers perpendicularly to the previous. Studying how parts perform with scan lines in a common direction, will assist in the understanding of how SLS parts behave in practice. Results showed that physical density, tensile strength and elongation rose with energy density up to 0.012 J/mm². This initial rise was due to a continued improvement in particle fusion with increasing energy density. Above 0.012 J/mm², these properties started to decline at different rates depending on their orientation (scan direction) on the part bed. Specimen’s oriented perpendicularly to the X axis exhibited a greater elongation at the expense of tensile strength, when compared to parallel specimens

Time-Resolved Optical and Thermal Analyses of High-Power Laser Diode Arrays

Time-resolved optical and thermal analyses of laser diode arrays reveals temperature induced chirp and the presence of anomalous hot spots

Development and validation of PozQoL: A scale to assess quality of life of PLHIV

Background: Advances in medical treatment for HIV are driving major changes in HIV policy and practice, including the encouragement of intake and adherence to HIV antiretroviral treatment (ART) by people living with HIV (PLHIV) for both personal and public health benefits. However, there is increasing recognition that achieving these goals will require a concurrent focus on the broader psychological and social wellbeing of PLHIV. Increasingly calls are being been made to incorporate a stronger focus on quality of life (QoL) of PLHIV into HIV prevention policy. In order to achieve this goal, HIV community, support and healthcare services need a valid, short and practical way to evaluate QoL of PLHIV accessing their programs. Current QoL measures are either long, complex, restricted in their use, or expensive. To address these shortcomings, the PozQoL study aimed to develop, test and validate a short and freely available scale assessing QoL among PLHIV. Methods: Drawing on a literature review, the prioritisation of domains and development of the initial pool of items was conducted in consultation with PLHIV community organisations in Australia. The items covered health concerns, psychological, social, and functional wellbeing. Testing involved a baseline and a follow-up survey of 465 adult Australians living with HIV. Participants were recruited through social media and various community organizations nationwide. The survey included the pilot PozQoL scale and other validated measures of health and wellbeing. Results: Guided by an Exploratory Factor Analysis and conceptual considerations, a 13-item scale was developed. The PozQoL scale demonstrated high levels of fit in a Confirmatory Factor Analysis, very good internal consistency, test-retest reliability, and concurrent validity with other measures that approximated different aspects of QoL. Conclusion: The PozQoL scale has been tested in a diverse sample of adult PLHIV living in Australia, demonstrating very good reliability and validity. The insights from PLHIV and other stakeholders supported the balancing of statistical rigour and conceptual accuracy. The scale is now ready to be implemented and field-tested across a range of community, support and healthcare programs for PLHIV. This will make a significant contribution to the evaluation and enhancement of programs for PLHIV

Airborne Lidar Measurements of Atmospheric Pressure Made Using the Oxygen A-Band

Accurate measurements of greenhouse gas mixing ratios on a global scale are currently needed to gain a better understanding of climate change and its possible impact on our planet. In order to remotely measure greenhouse gas concentrations in the atmosphere with regard to dry air, the air number density in the atmosphere is also needed in deriving the greenhouse gas concentrations. Since oxygen is stable and uniformly mixed in the atmosphere at 20.95%, the measurement of an oxygen absorption in the atmosphere can be used to infer the dry air density and used to calculate the dry air mixing ratio of a greenhouse gas, such as carbon dioxide or methane. OUT technique of measuring Oxygen uses integrated path differential absorption (IPDA) with an Erbium Doped Fiber Amplifier (EDF A) laser system and single photon counting module (SPCM). It measures the absorbance of several on- and off-line wavelengths tuned to an O2 absorption line in the A-band at 764.7 nm. The choice of wavelengths allows us to maximize the pressure sensitivity using the trough between two absorptions in the Oxygen A-band. Our retrieval algorithm uses ancillary meteorological and aircraft altitude information to fit the experimentally obtained lidar O2 line shapes to a model atmosphere and derives the pressure from the profiles of the two lines. We have demonstrated O2 measurements from the ground and from an airborne platform. In this paper we will report on our airborne measurements during our 2011 campaign for the ASCENDS program

Impressions of defensive medical practice and medical litigation among South African neurosurgeons

From a litigation perspective, neurosurgery is considered a ‘super high-risk’ field, and this has been associated with rapidly increasing malpractice cover costs. In 2013 the annual Medical Protection Society fee for cover was R250 900. We wished to determine whether high malpractice cover was influencing how neurosurgeons managed patients. A 40-question online survey asking questions on defensive medicine was distributed to determine perceptions around liability risk and whether these influenced how patients were managed. Eighty-four per cent of respondents agreed that a medicolegal crisis existed, and over half (53.8%) had been sued for malpractice during their career. Altering practice behaviour to minimise the risk of a lawsuit is common. The increasing number of legal claims against respondents in this survey has resulted in most neurosurgeons practising defensive medicine. Arguably this will result in increased healthcare costs, inferior patient care and decreased access to skilled surgeons.

Tuning the Swing Effect by Chemical Functionalization of Zeolitic Imidazolate Frameworks

Many zeolitic imidazolate frameworks (ZIFs) are promising candidates for use in separation technologies. Comprising large cavities interconnected by small windows they can be used, at least in principle, as molecular sieves where molecules smaller than the window size are able to diffuse into the material while larger molecules are rejected. However, "swing effect" or "gate opening" phenomena resulting in an enlargement of the windows have proven to be detrimental. Here, we present the first systematic experimental and computational study of the effect of chemical functionalization of the imidazole linker on the framework dynamics. Using high-pressure (HP) single-crystal X-ray diffraction, density functional theory, and grand canonical Monte Carlo simulations, we show that in the isostructural ZIF-8, ZIF-90, and ZIF-65 functional groups of increasing polarity (-CH 3, -CHO, and -NO 2) on the imidazole linkers provide control over the degree of rotation and thus the critical window diameter. On application of pressure, the substituted imidazolate rings rotate, resulting in an increase in both pore volume and content. Our results show that the interplay between the guest molecules and the chemical function of the imidazole linker is essential for directing the swing effect in ZIF frameworks and therefore the adsorption performance. </p

Persistent Hepatic Structural Alterations Following Nanoceria Vascular Infusion in the Rat

Understanding the long-term effects and possible toxicity of nanoceria, a widely utilized commercial metal oxide, is of particular importance as it is poised for development as a therapeutic agent based on its autocatalytic redox behavior. We show here evidence of acute and subacute adverse hepatic responses, after a single infusion of an aqueous dispersion of 85 mg/kg, 30 nm nanoceria into Sprague Dawley rats. Light and electron microscopic evidence of avid uptake of nanoceria by Kupffer cells was detected as early as 1 hr after infusion. Biopersistent nanoceria stimulated cluster of differentiation 3+ lymphocyte proliferation that intermingled with nanoceria-containing Kupffer cells to form granulomata that were observed between days 30 and 90. Ultrastructural tracking of ceria nanoparticles revealed aggregated nanoceria in phagolysosomes. An increased formation of small nanoceria over time observed in the latter suggests possible dissolution and precipitation of nanoceria. However, the pathway for nanoceria metabolism/secretion remains unclear. Although frank hepatic necrosis was not observed, the retention of nanoceria increased hepatic apoptosis acutely, this persisted to day 90. These findings, together with our earlier reports of 5-nm ceria-induced liver toxicity, provide additional guidance for nanoceria development as a therapeutic agent and for its risk assessment