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The search for life in the Universe is a fundamental problem of astrobiology and modern science. The current progress in the detection of terrestrial-type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favourable for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of global (astrospheric), and local (atmospheric and surface) environments of exoplanets in the habitable zones (HZs) around G-K-M dwarf stars including our young Sun. Global environment is formed by propagated disturbances from the planet-hosting stars in the form of stellar flares, coronal mass ejections, energetic particles and winds collectively known as astrospheric space weather. Its characterization will help in understanding how an exoplanetary ecosystem interacts with its host star, as well as in the specification of the physical, chemical and biochemical conditions that can create favourable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro)physical, chemical and geological processes can only be understood in the framework of interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets will significantly expand the current definition of the HZ to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of this paper is to describe and discuss the current status and recent progress in this interdisciplinary field in light of presentations and discussions during the NASA Nexus for Exoplanetary System Science funded workshop ‘Exoplanetary Space Weather, Climate and Habitability’ and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology.
The aim of this study was to compare patterns of cognitive decline in older Latinos and non-Latinos. At annual intervals for a mean of 5.7 years, older Latino (n=104) and non-Latino (n=104) persons of equivalent age, education, and race completed a battery of 17 cognitive tests from which previously established composite measures of episodic memory, semantic memory, working memory, perceptual speed, and visuospatial ability were derived. In analyses adjusted for age, sex, and education, performance declined over time in each cognitive domain, but there were no ethnic group differences in initial level of function or annual rate of decline. There was evidence of retest learning following the baseline evaluation, but neither the magnitude nor duration of the effect was related to Latino ethnicity, and eliminating the first two evaluations, during which much of retest learning occurred, did not affect ethnic group comparisons. Compared to the non-Latino group, the Latino group had more diabetes (38.5% vs. 25.0; χ2=4.4; p=.037), fewer histories of smoking (24.0% vs. 39.4%, χ2=5.7; p=.017), and lower childhood household socioeconomic level (−0.410 vs. −0.045, t[185.0]=3.1; p=.002), but controlling for these factors did not affect results. Trajectories of cognitive aging in different abilities are similar in Latino and non-Latino individuals of equivalent age, education, and race. (JINS, 2016, 22, 58–65)
The Murchison Widefield Array is a Square Kilometre Array Precursor. The telescope is located at the Murchison Radio–astronomy Observatory in Western Australia. The MWA consists of 4 096 dipoles arranged into 128 dual polarisation aperture arrays forming a connected element interferometer that cross-correlates signals from all 256 inputs. A hybrid approach to the correlation task is employed, with some processing stages being performed by bespoke hardware, based on Field Programmable Gate Arrays, and others by Graphics Processing Units housed in general purpose rack mounted servers. The correlation capability required is approximately 8 tera floating point operations per second. The MWA has commenced operations and the correlator is generating 8.3 TB day−1 of correlation products, that are subsequently transferred 700 km from the MRO to Perth (WA) in real-time for storage and offline processing. In this paper, we outline the correlator design, signal path, and processing elements and present the data format for the internal and external interfaces.
Desiccation following prolonged air exposure challenges survival of aquatic plants during droughts, water drawdowns, and overland dispersal. To improve predictions of plant response to air exposure, we observed the viability of vegetative fragments of 10 aquatic plant species (Cabomba caroliniana, Ceratophyllum demersum, Elodea canadensis, Egeria densa, Myriophyllum aquaticum, Myriophyllum heterophyllum, Myriophyllum spicatum, Potamogeton crispus, Potamogeton richardsonii, and Hydrilla verticillata) following desiccation. We recorded mass loss, desiccation rate, and plant fragment survival across a range of air exposures. Mass loss accurately predicted viability of aquatic plant fragments upon reintroduction to water. However, similar periods of air exposure differentially affected viability between species. Understanding viability following desiccation can contribute to predicting dispersal, improving eradication protocols, and disposing of aquatic plants following removal from invaded lakes or contaminated equipment.
The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80–300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3-km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper, the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised.
End tidal CO2 (ETCO2) has been established as a standard for confirmation of an airway, but its role is expanding. In certain settings ETCO2 closely approximates the partial pressure of arterial CO2 (PaCO2) and has been described as a tool to optimize a patient's ventilatory status. ETCO2 monitors are increasingly being used by EMS personnel to guide ventilation in the prehospital setting. Severely traumatized and burn patients represent a unique population to which this practice has not been validated.
The sole use of ETCO2 to monitor ventilation may lead to avoidable respiratory acidosis.
A consecutive series of patients with burns or trauma intubated in the prehospital setting over a 24-month period were evaluated. Prehospital arrests were excluded. Absence of ETCO2 transport data and patients without an arterial blood gas (ABG) within 15 minutes of arrival were also excluded. Data collected included demographics, place and time of intubation, service performing intubation, ETCO2 maintained en-route to hospital, and ABG upon arrival. Further data included length of stay, mortality, and injury severity scores.
One hundred sixty patients met the inclusion criteria. Prehospital ETCO2 did not correlate with measured PaCO2 (R2 = 0.08). Mean ETCO2 was significantly lower than mean PaCO2 (34 mmHg vs 44 mmHg, P < .005). Patients arriving acidotic were more likely to die. Mean pH on arrival for survivors and decedents was 7.32 and 7.19 respectively (P < .001). Mortality, acidosis, higher base deficits, and more severe injury patterns were all predictors for a worse correlation between ETCO2 and PaCO2 and increased mean difference between the two values. Decedents and patients presenting with a pH <7.2 demonstrated the greatest discrepancy between ETCO2 and PaCO2. The data suggest that patients may be hypoventilated by prehospital providers in order to obtain a prescribed ETCO2.
ETCO2 is an inadequate tool for predicting PaCO2 or optimizing ventilation in severely injured patients. Adherence to current ETCO2 guidelines in the prehospital setting may contribute to acidosis and increased mortality. Consideration should be given to developing alternate protocols to guide ventilation of the severely injured in the prehospital setting.
CooperCJ, KraatzJJ, KubiakDS, KesselJW, BarnesSL. Utility of Prehospital Quantitative End Tidal CO2?. Prehosp Disaster Med. 2013;28(2):1-6.
There is increasing epidemiological evidence linking sub-optimal vitamin D status with overweight and obesity. Although increasing BMI and adiposity have also been negatively associated with the change in vitamin D status following supplementation, results have been equivocal. The aim of this randomised, placebo-controlled study was to investigate the associations between anthropometric measures of adiposity and the wintertime serum 25-hydroxycholecalciferol (25(OH)D) response to 15 μg cholecalciferol per d in healthy young and older Irish adults. A total of 110 young adults (20–40 years) and 102 older adults ( ≥ 64 years) completed the 22-week intervention with >85 % compliance. The change in 25(OH)D from baseline was calculated. Anthropometric measures of adiposity taken at baseline included height, weight and waist circumference (WC), along with skinfold thickness measurements to estimate fat mass (FM). FM was subsequently expressed as FM (kg), FM (%), FM index (FMI (FM kg/height m2)) and as a percentage ratio to fat-free mass (FFM). In older adults, vitamin D status was inversely associated with BMI (kg/m2), WC (cm), FM (kg and %), FMI (kg/m2) and FM:FFM (%) at baseline (r − 0·33, − 0·36, − 0·33, − 0·30, − 0·33 and − 0·27, respectively, all P values < 0·01). BMI in older adults was also negatively associated with the change in 25(OH)D following supplementation (β − 1·27, CI − 2·37, − 0·16, P = 0·026); however, no such associations were apparent in younger adults. Results suggest that adiposity may need to be taken into account when determining an adequate wintertime dietary vitamin D intake for healthy older adults residing at higher latitudes.
The corrosion behaviour of Magnox Waste (MW) glass in deionized water has been investigated under the aegis of the Japanese-Swedish-Swiss (JSS) project. The studies carried out at PSI and BNFL included static leaching and corrosion layer characterization. The results were used by HMI to derive the modelling parameters for the MW glass with the PHREEQE/GLASSOL codes. The silica concentration was found to strongly influence the corrosion rate of the glass. The MW glass selectively retains Cs due to the formation of a Cs-Mg-Al-Si-O-rich layer on its surface.
We have examined the optical and transport properties of In.2Ga.8As/GaAs straled-kayer superlZotices (SLS's), which have been implanted either with 5 × 1015/cm2, 250keV Zn+ or with 5 × 1014/cm2, 70keV Be+ and annealed under an arsenic overpressure at 600 °C. For both cases, electrical activation in the implantation-doped regions equalled that of similar implants and anneals in bulk GaAs, even though the Be implant retained the SLS structure, while the Zn implant intermixed the SLS layers to produce an alloy semiconductor of the average SLS composition. Photoluminescence intensities in the annealed implanted regions were significantly reduced from that of virgin material, apparently due to residual implant damage. Diodes formed from both the Be- and the Zn-implanted SLS's produced electroluminescence intensity comparable to that of grown-junction SLS diodes in the same chemical system, despite the implantation processing and the potential for vertical lattice mismatch in the Zn-disordered SLS device. These results indicate that Zn-disordering can be as useful in strained-layer superlattices as in lattice-matched systems.
Efficient 1.54 μm emission under 1064nm excitation of Er3+/Yb3+ codoped silica fibre is reported. The energy transfer efficiency from Yb3+ to Er3+, of at least 85%, even under high inversion, is comparable to that in multicomponent glass fibres. Fibre design parameters are discussed and results presented. Small signal gain of ˜ 45dB is also measured and a power amplifier giving 145mW output power demonstrated.
Space-borne laser remote sensing systems typically rely on conductively cooled, diodepumped solid-state lasers as their transmitter source. Since space-borne instruments incur high developmental and launch costs and are inaccessible for maintenance, their reliability is of great importance. Therefore, it is crucial to address the reliability of high power laser pump arrays, which essentially dictate the reliability and lifetime of the laser systems. The most common solid-state lasers used for remote sensing applications are Neodymium-based, 1-micron lasers and Thulium/Holmium based 2-micron lasers. 2-micron lasers require a pump wavelength of around 10 to 20 nm shorter compared with 1-micron lasers, and require pump pulse durations 5 to 10 times longer. This work focuses on the long pulsewidth laser diode arrays (LDAs) operating at a central wavelength of 792 nm used for optically pumping 2-micron solid-state laser materials. Such LDAs are required to operate at relatively high pulse energies with pulse durations on the order of one millisecond. However, such relatively long pulse durations cause the laser diode active region to experience high peak temperatures and drastic thermal cycling. This extreme localized heating and thermal cycling of the active regions are considered the primary contributing factors for both gradual and catastrophic degradation of LDAs, thus limiting their reliability and lifetime. One method for mitigating this damage is to incorporate materials that can improve thermo-mechanical properties by increasing the rate of heat dissipation and reducing internal stresses due to differences in thermal expansion and thus increasing lifetime. This paper explains the need for long pulsewidth operation, how this affects reliability and lifetime and presents some results from characterization and life testing of these devices.
Pr doped YBa2Cu3O7-d targets with composition Y1-xPrxBa2Cu3O7-d where × = 0.0001, 0.001, 0.01, and 0.1 were prepared from oxide powders and were used to deposit thin films by pulsed laser deposition using conditions previously optimized for pure YBa2Cu3O7-d. The Pr dopant was found to be dispersed throughout the film by secondary ion mass spectrometry and found to have an increased density of nanoparticles on the surface. The pinning force of the doped samples was found to decrease with increasing concentration of Pr; however, at 0.01% concentration the doped film displayed a significant enhancement over pure YBa2Cu3O7-d for nearly the full range of 0 – 9 T.