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Radnor Lake State Natural Area in Nashville, TN, has cedar glades that contain the endangered perennial herb wild dill [Perideridia americana (Nutt. ex DC.) Rchb.] and the invasive shrub Amur honeysuckle [Lonicera maackii (Rupr.) Herder]. This research examined whether L. maackii treatment in the Radnor Lake State Natural Area cedar glades is followed by an increase in P. americana plants. A grid of 60 adjacent 2 m by 4 m plots was placed in five cedar glades to encompass the P. americana population. With great care to protect P. americana, the annual treatment for L. maackii was to pull plants ≤1-m tall from the ground; and to cut stems >1-m tall and then treat the stumps with glyphosate. The t-tests of means for the log natural of the number of plants in the 60 plots (significance level of P-value = 0.05) were used to compare pretreatment L. maackii and P. americana counts with posttreatment counts in 2018 and P. americana counts at leaf out and flowering in 2018. The L. maackii population was significantly smaller (P-value < 0.001) in 2018 than pretreatment at all five sites. When pretreatment in 2014 and 2015 was compared with posttreatment in 2018 for the P. americana populations, the increases were significant at the Cheek, Harris 2, Hideaway, and Norfleet sites, but the increase at East Hall Farm was not significant. White-tailed deer (Odocoileus virginianus Zimmermann) trampling was the explanation given for the decreases in P. americana from leaf out to flowering at all five sites in 2018. Browsing was evident only at Hideaway, which had a greater loss for P. americana from leaf out to flowering in 2018 than the combined losses for the Cheek, East Hall Farm, Harris 2, and Norfleet sites. The research informed the creation of adaptive management decisions regarding monitoring and treatment of the invasive species L. maackii for an endangered species.
The expanding range of disease modifying therapies (DMT) for relapsing-remitting multiple sclerosis (RRMS) has led to increased interest in the relative effects of different DMTs. Previous mixed treatment comparisons (MTCs) have used different methods to address similar questions highlighting the need for a consistent approach to the assessment of treatments in RRMS.
We compared the methodology of six published MTCs of DMTs for RRMS identified by a systematic search of the literature. We assessed sources of evidence, DMTs included, outcomes reported and methods of data synthesis.
All six MTCs were based on systematic reviews that included randomized controlled trials (RCTs). MS relapse was reported as the rate ratio based on annualised relapse rates (four MTCs) and as odds ratios or relative risk (one MTC each) based on the proportion with relapse. The analysis of relapse included between sixteen and twenty-seven RCTs and seven to twenty DMTs in different MTCs. One MTC reported both disability progression confirmed after three months (CDP3M) and disability progression confirmed after six months (CDP6M) as hazard ratios. One MTC combined CDP3M and CDP6M as a single outcome. One MTC reported only CDP3M based on hazard ratios. Two MTCs reported only CDP6M as either odds ratios or risk ratios (one MTC each). In one MTC the definition of disability progression was not reported. The analysis of disability included between seven and twenty-six RCTs and between six and nineteen DMTs in different MTCs. All six MTCs fitted a random effects MTC model using either Bayesian (four MTCs) or frequentist (two MTCs) methods.
There is substantial heterogeneity between published MTCs in RRMS with regard to inclusion criteria, outcome definitions, effect measures and statistical methods. There is a clear requirement for a consistent approach to health technology assessment of DMTs for RRMS.
The SETI@home project has recently completed its third year of active data analysis. Over 4 million volunteers have joined the search, providing a combined total of over 1 million CPU-years of processing power. SETI@home performs a sensitive search for extraterrestrial signals in a 2.5 MHz band centered on 1420 MHz. SETI@home searches a wide parameter space including 14 octaves of signal bandwidth and 15 octaves of pulse period with Doppler drift corrections from −50 Hz/s to +50 Hz/s. We will briefly describe the SETI@home project and the algorithms used in the SETI@home client. We will describe the post-processing methods we use to reject RFI and select candidate signals from the nearly 4 billion “hits” returned by SETI@home clients.
The WISSARD (Whillans Ice Stream Subglacial Access Research Drilling) traversable hot-water drill system was designed to create various-diameter ice boreholes to a depth of >800 m, with most major components being controllable from a single user interface. The drill control system operates four low-pressure pumps for water generation and circulation, two hot-water generation units containing a total of six diesel burner modules with integrated high-pressure pumps, three winches (one with independent level-wind motor), a four-motor linear traction drive, and a large number of analog and digital sensors to monitor system performance and cleanliness. Due to development time constraints the control system design focused on utilizing commercial off-the-shelf components, while being highly modular, easily expandable and rapidly deployable. Additional emphasis was placed on providing redundant manual operator controls and maintaining a low degree of system automation to avoid dependence on software control loops for first-season deployment. The result of this design paradigm was a control system that was taken from concept to full operation in <6 months, successfully performing in the field without insurmountable problems.
A new, clean, hot-water drill system (HWDS) was developed by the Science Management Office, University of Nebraska-Lincoln, for use in the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project to gain access to Subglacial Lake Whillans beneath ∼800 m of ice in West Antarctica. One primary borehole was drilled into the basal ice environment of Subglacial Lake Whillans during the initial field season in 2012/13. This paper describes the process of designing, fabricating, assembling, shipping, testing, commissioning and traversing the WISSARD HWDS leading up to the first scientific use of the system.
Radon gas is a serious contaminant in radiocarbon dating by radiometry. The low specific ionizations associated with the α-particle emitting radon and its β-particle emitting daughters overlap within the 14C counting window. Elimination of radon is therefore imperative for precise 14C age determinations. This paper deals with the sources and mechanism of incorporation of radon affecting 14C dating by liquid scintillation (LS) counting, and reviews conventional radon elimination practices in 14C laboratories. It demonstrates, based on rigorous multichannel and multiparameter α- and β-particle spectral analyses of some 1000 benzene samples, that parent radium is not present and that its daughter radon is quantitatively eliminated during dynamic vacuum recovery of benzene at −78°C. However, the radon-free benzene can be recontaminated by exposure to air containing traces of radon, such as is common in concrete or low-lying laboratories. The use of radon-free air, when exposing the benzene to the atmosphere, and the monitoring of radon counts from the environment and sample benzene in a fixed ‘radon window', are essential prerequisites to the quality control of 14C age determinations in very low background systems.
LMC2 was one of the first supergiant shells in the Large Magellanic Cloud (LMC) to be identified, based on the detection of long, curved Hα filaments extending over 900 pc (Goudis & Meaburn 1978). LMC 2 is located to the east of the active star formation region south of 30 Doradus. LMC 2 is a spectacular supergiant shell in the LMC, having the most coherent filamentary structure and the highest X-ray surface brightness. As shown in Fig. 1, the diffuse X-ray emission from LMC 2 is bounded by the Hα filaments in the north and east. A bright X-ray arc is seen in the southwest quadrant, extending from N 158 and N 159.
We present far-UV spectra of the three magnetic cataclysmic variables (MCVs) BY Cam, V1309 Ori and AE Aqr obtained with the FUSE satellite. These MCVs have revealed strongly unusual NV and CIV UV resonance lines. The FUSE spectra exhibit broad OVI lines as well as a strong NIII line at 991Å, while the CIII 1175Å line is nearly absent, supporting non-solar CNO abundances of the accreting matter in these sources. The spectrum of BY Cam shows molecular H2 lines which might be of circumstellar nature. The flaring activity of AE Aqr is also observed in the far-UV range. The radial velocities of the broad OVI components in AE Aqr are orbitally modulated and would indicate an emission region close to the magnetosphere.
We apply n- and p-type polycrystalline silicon (poly-Si) films on tunneling SiOx to form passivated contacts to n-type Si wafers. The resulting induced emitter and n+/n back surface field junctions of high carrier selectivity and low contact resistivity enable high efficiency Si solar cells. This work addresses the materials science of their performance governed by the properties of the individual layers (poly-Si, tunneling oxide) and more importantly, by the process history of the cell as a whole. Tunneling SiOx layers (<2 nm) are grown thermally or chemically, followed by a plasma enhanced chemical vapor deposition growth of p+ or n+ doped a-Si:H. The latter is thermally crystallized into poly-Si, resulting in grain nucleation and growth as well as dopant diffusion within the poly-Si and penetration through the tunneling oxide into the Si base wafer. The cell process is designed to improve the passivation of both oxide interfaces and tunneling transport through the oxide. A novel passivation technique involves coating of the passivated contact and whole cell with atomic layer deposited Al2O3 and activating them at 400 °C. The resulting excellent passivation persists after subsequent chemical removal of the Al2O3. The preceding cell process steps must be carefully tailored to avoid structural and morphological defects, as well as to maintain or improve passivation, and carrier selective transport. Furthermore, passivated contact metallization presents significant challenges, often resulting in passivation loss. Suggested remedies include improved Si cell wafer surface morphology (without micropyramids) and postdeposited a-Si:H capping layers over the poly-Si.
We demonstrated the fabrication of 10 emitters InGaN laser diode array of the
maximum output power of 9 W at 420 nm. The device as a whole has the
differential efficiency of above 1 W/A. The maximum output power is limited to 9
W (pulse operation) by catastrophic mirror damage or to around 5 W in CW
operation by thermal roll-over. Larger arrays with stripes width of around 15
µm and numbers of emitters up to 20 should enable reaching 20 W, which
is suitable for light engine of desktop projectors and a building block of
cinema theater projectors.
This triennium has seen progress in a number of directions related to Commission 20 objectives. Foremost, the growth in the number of astrometric observations of small solar system bodies continues to accelerate and the total number of measurements recorded by the Minor Planet Center now exceeds 135 million. Currently the Pan-STARRS project and the Catalina Sky Survey (CSS) dominate detection and discovery efforts, while the NEO-WISE space mission contributes infrared detections valuable for understanding the size distribution of populations. Looking forward, the Large Synoptic Survey Telescope (LSST) is now funded and in construction on Cerro Pachon in Chile. LSST has the potential to revolutionize the field by conducting a multi-color, ten-year, all-sky survey with a limiting magnitude ~24.5 in the r-band. Survey operations are set to begin in 2022.
In our earlier work  microstructural evolution in tungsten under self-ion irradiation was investigated as a function of temperature and dose by in-situ 150 keV W+ ion irradiations on the IVEM-Tandem facility at Argonne National Laboratory (ANL). The present work focuses on the thermal stability of this damage. Thin foils of tungsten were irradiated at room temperature (R.T.) to fluences up to 1018 W+m-2 (∼ 1.0 dpa) and were then annealed in-situ for up to 120 min at temperatures between 300 and 800°C.
We found that: (1) loops with Burgers vectors ½ <111> and <100> coexist during annealing; (2) <100> is not a stable loop configuration above 300°C and the fraction of such loops decreased with increasing temperature and/or time; (3) changes in loop populations during annealing were very sensitive to temperature, but less sensitive to time. The majority of changes occurred within 15 min, and were associated with the loss of small (1-2 nm) dislocation loops. The origin of these trends is discussed by considering defect mobility and the energetics of defect configurations predicted by previous DFT calculations .
The montane inselbergs of northern Mozambique have been comparatively little-studied, yet recent surveys have shown they have a rich biodiversity with numerous endemic species. Here we present the main findings from a series of scientific expeditions to one of these inselbergs, Mt Mabu, and discuss the conservation implications. Comprehensive species lists of plants, birds, mammals and butterflies are presented. The most significant result was the discovery of a c. 7,880 ha block of undisturbed rainforest, most of it at medium altitude (900–1,400 m), a forest type that is not well represented elsewhere. It is possibly the largest continuous block of this forest type in southern Africa. To date, 10 new species (plants, mammals, reptiles and butterflies) have been confirmed from Mt Mabu, even though sampling effort for most taxonomic groups has been low. The species assemblages indicate a relatively long period of isolation and many species found are at the southern limit of their range. Conservationists are now faced with the challenge of how best to protect Mt Mabu and similar mountains in northern Mozambique, and various ways that this could be done are discussed.