5,701 research outputs found
Tipping back the balance: recolonization of the Macquarie Island isthmus by king penguins (Aptenodytes patagonicus) following extermination for human gain
During the late 19th and early 20th centuries, when blubber oil fuelled house lamps, the king penguin population at Macquarie Island was reduced from two very large (perhaps hundreds of thousands of birds) colonies to about 3000 birds. One colony, located on the isthmus when the island was discovered in 1810, was extinct by 1894 and it took about 100 years for king penguins to re-establish a viable breeding population there. Here we document this recovery. The first eggs laid at Gadget Gully on the isthmus were recorded in late February 1995 but in subsequent years egg laying took place earlier between November and February (this temporal discontinuity is a consequence of king penguin breeding behaviour). The first chick was hatched in April 1995 but the first fledging was not raised until the following breeding season in October 1996. The colony increased on average 66% per annum in the five years between 1995 and 2000. King penguins appear resilient to catastrophic population reductions, and as the island\u27s population increases, it is likely that other previously abandoned breeding sites will be reoccupied
NLO corrections in MC event generator for angular distribution of Drell-Yan lepton pair production
Using a subtraction method, we derive the formulae suitable for use in
Monte-Carlo event generators to give the angular distribution for the
gluon-quark induced NLO corrections in Drell-Yan lepton pair production. We
also give the corresponding helicity density matrix for W and Z boson
production.Comment: 14 pages, 2 figure
The impact of tensioning device mal-positioning on strand tension during Anterior Cruciate Ligament reconstruction
<p>Abstract</p> <p>Background</p> <p>In order to confer optimal strength and stiffness to the graft in Anterior Cruciate Ligament (ACL) reconstruction, the maintenance of equal strand tension prior to fixation, is desired; positioning of the tensioning device can significantly affect strand tension This study aimed to determine the effect of tensioning device mal-positioning on individual strand tension in simulated cadaveric ACL reconstructions.</p> <p>Methods</p> <p>Twenty cadaveric specimens, comprising bovine tibia and tendon harvested from sheep, were used to simulate ACL reconstruction with a looped four-strand tendon graft. A proprietary tensioning device was used to tension the graft during tibial component fixation with graft tension recorded using load cells. The effects of the tensioning device at extreme angles, and in various locking states, was evaluated.</p> <p>Results</p> <p>Strand tension varied significantly when the tensioning device was held at extreme angles (p < 0.001) or in 'locked' configurations of the tensioning device (p < 0.046). Tendon position also produced significant effects (p < 0.016) on the resultant strand tension.</p> <p>Conclusion</p> <p>An even distribution of tension among individual graft strands is obtained by maintaining the tensioning device in an unlocked state, aligned with the longitudinal axis of the tibial tunnel. If the maintenance of equal strand tension during tibial fixation of grafts is important, close attention must be paid to positioning of the tensioning device in order to optimize the resultant graft tension and, by implication, the strength and stiffness of the graft and ultimately, surgical outcome.</p
Analysis of grain-boundary structure in AlâCu interconnects
The role of crystallographic texture in electromigration resistance of interconnect lines is well documented. The presence of a strong (111) fiber texture results in a more reliable interconnect structure. It is also generally accepted that grain-boundary diffusion is the primary mechanism by which electromigration failures occur. It has been difficult to this point, however, to obtain statistically reliable information of grain-boundary structure in these materials as transmission electron microscopy investigations are limited by tedious specimen preparation and small, nonrepresentative, imaging regions. The present work focuses upon characterization of texture and grain-boundary structure of interconnect lines using orientation imaging microscopy, and particularly, upon the linewidth dependence of these measures. Conventionally processed Alâ1%Cu lines were investigated to determine the affects of a postpatterning anneal on boundary structure as a function of linewidth. It was observed that texture tended to strengthen slightly with decreasing linewidth subsequent to the anneal procedure. Grain morphology changed substantially as the narrow lines became near bamboo in character and the crystallographic character of the boundary plane changed as a function of linewidth. These results are contrasted with those obtained from Alâ1%Cu lines, which were fabricated using the damascene process. The damascene lines show a marked weakening in texture as the linewidth decreases, accompanied by a more random misorientation distribution. A description of the competing energetics, which result in the observed microstructures, is included. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71133/2/JAPIAU-82-5-2383-1.pd
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Economic Impact of the Cleantech Sector in the Austin-Round Rock-San Marcos MSA
Economic impact report for the clean technology sector in central Texas, commissioned by CleanTX and supported by the Austin Technology Incubator and Civic Analytics. The study finds that the cleantech sector in the Austin region directly employs nearly 20,000 individuals and contributes approximately $2.5 billion to the region's GDP. In addition, it projects cleantech employment from 2014-2020 to grow 11.24% in the Austin MSA, as compared with 9.3% growth in the sector over the same period at the state level, and 6.37% nationally. The report identifies seven specific technology areas which represent opportunities for growth: renewables; energy storage and "smart grid" technologies; smart cities and resilient infrastructure; autonomous vehicles and connected mobility; water management; recycling and waste management; and advanced manufacturing.IC2 Institut
NMFS / Interagency Working Group Evaluation of CITES Criteria and Guidelines.
EXECUTIVE SUMMARY: At present, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) criteria used to assess whether a population qualifies for inclusion in the CITES Appendices relate to (A) size of the population, (B) area of distribution of the population, and (C) declines in the size of the population. Numeric guidelines are provided as indicators of a small population (less than 5,000 individuals), a small subpopulation (less than 500 individuals), a restricted area of distribution for a population (less than 10,000 km2), a restricted area of distribution for a subpopula-tion (less than 500 km2), a high rate of decline (a decrease of 50% or more in total within 5 years or two generations whichever is longer or, for a small wild population, a decline of 20% or more in total within ten years or three generations whichever is longer), large fluctuations (population size or area of distribution varies widely, rapidly and frequently, with a variation greater than one order of magnitude), and a short-term fluctuation (one of two years or less).
The Working Group discussed several broad issues of relevance to the CITES criteria and guidelines. These included the importance of the historical extent of decline versus the recent rate of decline; the utility and validity of incorporating relative population productivity into decline criteria; the utility of absolute numbers for defining small populations or small areas; the appropriateness of generation times as time frames for examining declines; the importance of the magnitude and frequency of fluctuations as factors affecting risk of extinction; and the overall utility of numeric thresh-olds or guidelines
Observation of playa salts as nuclei in orographic wave clouds
During the Ice in Clouds Experiment-Layer Clouds (ICE-L), dry lakebed, or playa, salts from the Great Basin region of the United States were observed as cloud nuclei in orographic wave clouds over Wyoming. Using a counterflow virtual impactor in series with a single-particle mass spectrometer, sodium-potassium-magnesium-calcium-chloride salts were identified as residues of cloud droplets. Importantly, these salts produced similar mass spectral signatures to playa salts with elevated cloud condensation nuclei (CCN) efficiencies close to sea salt. Using a suite of chemical characterization instrumentation, the playa salts were observed to be internally mixed with oxidized organics, presumably produced by cloud processing, as well as carbonate. These salt particles were enriched as residues of large droplets (>19 ÎŒm) compared to smaller droplets (>7 ÎŒm). In addition, a small fraction of silicate-containing playa salts were hypothesized to be important in the observed heterogeneous ice nucleation processes. While the high CCN activity of sea salt has been demonstrated to play an important role in cloud formation in marine environments, this study provides direct evidence of the importance of playa salts in cloud formation in continental North America has not been shown previously. Studies are needed to model and quantify the impact of playas on climate globally, particularly because of the abundance of playas and expected increases in the frequency and intensity of dust storms in the future due to climate and land use changes
Assessing direct contributions of morphological awareness and prosodic sensitivity to childrenâs word reading and reading comprehension
We examined the independent contributions of prosodic sensitivity and morphological awareness to word reading, text reading accuracy, and reading comprehension. We did so in a longitudinal study of English-speaking children (N = 70). At 5 to 7 years of age, children completed the metalinguistic measures along with control measures of phonological awareness and vocabulary. Children completed the reading measures two years later. Morphological awareness, but not prosodic sensitivity made a significant independent contribution to word reading, text reading accuracy and reading comprehension. The effects of morphological awareness on reading comprehension remained after controls for word reading. These results suggest that morphological awareness needs to be considered seriously in models of reading development and that prosodic sensitivity might have primarily indirect relations to reading outcomes.
Keywords: Morphological Awareness; Prosody; Word Reading; Reading Comprehension
Residential radon-222 exposure and lung cancer: exposure assessment methodology
Although occupational epidemiological studies and animal experimentation provide strong evidence that radon-222 (222Rn) progeny exposure causes lung cancer, residential epidemiological studies have not confirmed this association. Past residential epidemiological studies have yielded contradictory findings. Exposure misclassification has seriously compromised the ability of these studies to detect whether an association exists between 222Rn exposure and lung cancer. Misclassification of 222Rn exposure has arisen primarily from: 1) detector measurement error; 2) failure to consider temporal and spatial 222Rn variations within a home; 3) missing data from previously occupied homes that currently are inaccessible; 4) failure to link 222Rn concentrations with subject mobility; and 5) measuring 222Rn gas concentration as a surrogate for 222Rn progeny exposure. This paper examines these methodological dosimetry problems and addresses how we are accounting for them in an ongoing, population-based, case-control study of 222Rn and lung cancer in Iowa
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