979 research outputs found
Some properties of Potato Virus M (PVM) in Crude Sap and in Pure Preparations
A study was performed to determine some properties of the potato virus M (PVM) in crude sap
and in pure preparations. In crude sap the virus was shown to have a dilution end point value of
10- 4, longevity in vitro particles sedimented as one peak with a sedimentation coefficient value of
162 s. The buoyant density in cesium chloride was 1.304 gm/cm ~ Electrophoresis in polyacrylamide
gels showed that the virus possessed only one protein subunit with a molecular weight of 39,300
daltons
Centrifuge Modelling of the Collapse of Shaft Linings
The collapse of abandoned and often hidden mine shafts is a serious problem in the UK and many parts of Europe. The collapse of these shafts is often related to the failure of the shaft lining. Understanding the mechanisms of ground movements around deforming/collapsing mine shafts is, therefore, important in the assessment of mine shaft location as well as lining condition. This paper presents an experimental study of the mechanisms of soil failure around a deforming shaft lining. Geotechnical centrifuge modelling of reduced-scale buried mine shafts was tested to determine the magnitude and pattern of ground deformations that occurred during loss of internal support pressure. An axis-symmetric centrifuge container was used along with half-cylindrical model shafts. These allowed for the acquisition of digital images of the sub-surface soil and mine shafts which enabled the measurement of soil and shaft deformation using image analysis techniques. The results from two model shaft tests are presented. The first test involved the loss of internal support along the entire shaft length, whereas the second test studied the effect of a discrete weakened zone within the lining
An authoritative global database for active submarine hydrothermal vent fields
Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 14 (2013): 4892â4905, doi:10.1002/2013GC004998.The InterRidge Vents Database is available online as the authoritative reference for locations of active submarine hydrothermal vent fields. Here we describe the revision of the database to an open source content management system and conduct a meta-analysis of the global distribution of known active vent fields. The number of known active vent fields has almost doubled in the past decade (521 as of year 2009), with about half visually confirmed and others inferred active from physical and chemical clues. Although previously known mainly from mid-ocean ridges (MORs), active vent fields at MORs now comprise only half of the total known, with about a quarter each now known at volcanic arcs and back-arc spreading centers. Discoveries in arc and back-arc settings resulted in an increase in known vent fields within exclusive economic zones, consequently reducing the proportion known in high seas to one third. The increase in known vent fields reflects a number of factors, including increased national and commercial interests in seafloor hydrothermal deposits as mineral resources. The purpose of the database now extends beyond academic research and education and into marine policy and management, with at least 18% of known vent fields in areas granted or pending applications for mineral prospecting and 8% in marine protected areas.For support to prepare this manuscript, we thank the National
Science Foundation (OCE08-38923, GeoEd12-02977), the
NOAA Vents (now Earth-Ocean Interactions) Program and
the Joint Institute for the Study of the Atmosphere and Ocean
(JISAO) under NOAA Cooperative Agreement
NA10OAR4320148, and WHOI.2014-05-1
Quantum nondemolition detection of a propagating microwave photon
The ability to nondestructively detect the presence of a single, traveling
photon has been a long-standing goal in optics, with applications in quantum
information and measurement. Realising such a detector is complicated by the
fact that photon-photon interactions are typically very weak. At microwave
frequencies, very strong effective photon-photon interactions in a waveguide
have recently been demonstrated. Here we show how this type of interaction can
be used to realize a quantum nondemolition measurement of a single propagating
microwave photon. The scheme we propose uses a chain of solid-state 3-level
systems (transmons), cascaded through circulators which suppress photon
backscattering. Our theoretical analysis shows that microwave-photon detection
with fidelity around 90% can be realized with existing technologies
Giant Cross Kerr Effect for Propagating Microwaves Induced by an Artificial Atom
We have investigated the cross Kerr phase shift of propagating microwave
fields strongly coupled to an artificial atom. The artificial atom is a
superconducting transmon qubit in an open transmission line. We demonstrate
average phase shifts of 11 degrees per photon between two coherent microwave
fields both at the single-photon level. At high control power, we observe phase
shifts up to 30 degrees. Our results provide an important step towards quantum
gates with propagating photons in the microwave regime.Comment: 5 pages, 4 figure
Quantitative atomic spectroscopy for primary thermometry
Quantitative spectroscopy has been used to measure accurately the
Doppler-broadening of atomic transitions in Rb vapor. By using a
conventional platinum resistance thermometer and the Doppler thermometry
technique, we were able to determine with a relative uncertainty of
, and with a deviation of from the
expected value. Our experiment, using an effusive vapour, departs significantly
from other Doppler-broadened thermometry (DBT) techniques, which rely on weakly
absorbing molecules in a diffusive regime. In these circumstances, very
different systematic effects such as magnetic sensitivity and optical pumping
are dominant. Using the model developed recently by Stace and Luiten, we
estimate the perturbation due to optical pumping of the measured value
was less than . The effects of optical pumping on atomic and
molecular DBT experiments is mapped over a wide range of beam size and
saturation intensity, indicating possible avenues for improvement. We also
compare the line-broadening mechanisms, windows of operation and detection
limits of some recent DBT experiments
Molecular footprints of the Holocene retreat of dwarf birch in Britain
© 2014 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited
Mystical orientation and the perceiving process : a study among Anglican clergymen
This study examines the hypothesised link between mystical orientation and the perceiving process within the Jungian model of psychological type. Data were provided by 232 Anglican clergymen serving in the Church in Wales who completed both the Francis-Louden Mystical Orientation Scale and the Francis Psychological Type Scales. The data demonstrated that intuitive types recorded significantly higher scores than sensing types on the index of mystical orientation, supporting the hypothesis based on Ross' thesis
Introduced plants as novel Anthropocene habitats for insects
Major environmental changes in the history of life on Earth have given rise to novel habitats, which gradually accumulate species. Humanâinduced change is no exception, yet the rules governing species accumulation in anthropogenic habitats are not fully developed. Here we propose that nonnative plants introduced to Great Britain may function as analogues of novel anthropogenic habitats for insects and mites, analysing a combination of localâscale experimental plot data and geographicâscale data contained within the Great Britain Database of Insects and their Food Plants. We find that novel plant habitats accumulate the greatest diversity of insect taxa when they are widespread and show some resemblance to plant habitats which have been present historically (based on the relatedness between native and nonnative plant species), with insect generalists colonizing from a wider range of sources. Despite reduced perâplant diversity, nonnative plants can support distinctive insect communities, sometimes including insect taxa that are otherwise rare or absent. Thus, novel plant habitats may contribute to, and potentially maintain, broaderâscale (assemblage) diversity in regions that contain mixtures of longâstanding and novel plant habitats
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