1,253 research outputs found
Jet engine powers large, high-temperature wind tunnel
Wind tunnel for large component testing uses a jet engine with afterburner to provide high temperatures /1200 degrees to 2000 degrees F/ and controlled high velocity gas. This economical wind tunnel can accommodate parts ten feet by ten feet or larger, and is a useful technique for qualitative information
Allometry and growth of eight tree taxa in United Kingdom woodlands.
This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative
Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0As part of a project to develop predictive ecosystem models of United Kingdom woodlands we have collated data from two United Kingdom woodlands - Wytham Woods and Alice Holt. Here we present data from 582 individual trees of eight taxa in the form of summary variables relating to the allometric relationships between trunk diameter, height, crown height, crown radius and trunk radial growth rate to the tree's light environment and diameter at breast height. In addition the raw data files containing the variables from which the summary data were obtained. Large sample sizes with longitudinal data spanning 22 years make these datasets useful for future studies concerned with the way trees change in size and shape over their life-span
Can one predict DNA Transcription Start Sites by studying bubbles?
It has been speculated that bubble formation of several base-pairs due to
thermal fluctuations is indicatory for biological active sites. Recent
evidence, based on experiments and molecular dynamics (MD) simulations using
the Peyrard-Bishop-Dauxois model, seems to point in this direction. However,
sufficiently large bubbles appear only seldom which makes an accurate
calculation difficult even for minimal models. In this letter, we introduce a
new method that is orders of magnitude faster than MD. Using this method we
show that the present evidence is unsubstantiated.Comment: 4 pages, 3 figures, accepted for publication in physical review
letter
Bubbles and denaturation in DNA
The local opening of DNA is an intriguing phenomenon from a statistical
physics point of view, but is also essential for its biological function. For
instance, the transcription and replication of our genetic code can not take
place without the unwinding of the DNA double helix. Although these biological
processes are driven by proteins, there might well be a relation between these
biological openings and the spontaneous bubble formation due to thermal
fluctuations. Mesoscopic models, like the Peyrard-Bishop-Dauxois model, have
fairly accurately reproduced some experimental denaturation curves and the
sharp phase transition in the thermodynamic limit. It is, hence, tempting to
see whether these models could be used to predict the biological activity of
DNA. In a previous study, we introduced a method that allows to obtain very
accurate results on this subject, which showed that some previous claims in
this direction, based on molecular dynamics studies, were premature. This could
either imply that the present PBD should be improved or that biological
activity can only be predicted in a more complex frame work that involves
interactions with proteins and super helical stresses. In this article, we give
detailed description of the statistical method introduced before. Moreover, for
several DNA sequences, we give a thorough analysis of the bubble-statistics as
function of position and bubble size and the so-called -denaturation curves
that can be measured experimentally. These show that some important
experimental observations are missing in the present model. We discuss how the
present model could be improved.Comment: 15 pages, 5 figures, published as Eur. Phys. J. E 20 : 421-434 AUG
200
Comparison of Best Management Practice Adoption Between Virginia\u27s Chesapeake Bay Basin and Southern Rivers Watersheds
Producers in two regions of Virginia (Chesapeake Bay basin and Southern Rivers region) were surveyed to compare farming practices and agricultural best management practice (BMP) adoption. Objectives were to assess farming operations and determine the extent of cost-share and non-cost-share BMP implementation and gain insight into the impact of selected socioeconomic factors on the BMP adoption. Although farming characteristics and producer attitudes toward pollution and water quality were similar, BMP implementation differed between the two regions. Differences in BMP implementation may be due to a more focused, longer-term NPS pollution control educational effort in the Bay basin
A comparison of handwritten and computer-assisted prescriptions in an intensive care unit
BACKGROUND: We conducted a prospective comparative study to evaluate the potential benefit of computer-assisted prescribing (CAP). We compared the accuracy, completeness and time use of CAP with that of conventional handwritten prescribing at the intensive care unit (ICU) of the John Radcliffe Hospital, Oxford, UK. RESULTS: Twenty-five clinicians and 2409 drug entries were evaluated for accuracy, completeness, legibility and time spent prescribing. One hundred and twenty-eight handwritten and 110 CAP charts were monitored. One hundred percent of CAP charts were complete compared to 47% of handwritten charts.Drug prescriptions were divided into three categories: intravenous fluids, intravenous infusions and intermittent drugs. Percentage of correct entries in each category were 64%, 47.5% and 90% for handwritten, compared to 48%, 32% and 90% for CAP charts, respectively.The mean time taken to prescribe was 20 s for hand written prescribing and 55 s for CAP. CONCLUSIONS: Computer-assisted prescriptions were more complete, signed and dated than handwritten prescriptions. Errors in prescribing, including failure to discontinue a drug were not reduced by CAP. Handwritten prescribing was quicker than CAP. Simple enhancements of the computer software could be introduced which might overcome these deficiencies. CAP was successfully integrated into clinical practice in the ICU
P5_2 Spaghettification: Surviving a Black Hole Event Horizon
We found that it is possible to stay conscious falling through the event horizon of aBlack Hole if the mass exceeds 19,000M_sol. This assumes the average person is ofgood health and can stay conscious with a relative force less than 5 g acting upon them
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