2,431 research outputs found
An examination of the effects of size and isolation on the wildlife conservation value of wooded sites. I. Birds
Conjugacy in VLF Emissions
VLF emissions observed simultaneously in opposite magnetic hemispheres of the earth often show marked similarities. The correlation is best when the receivers are close to the opposite ends of a magnetic line of force. Echoing emissions show the same travel times as associated whistlers, indicating that they travel over the same discrete paths. Conjugacy in VLF emissions is observed most commonly with periodic and quasi-periodic emissions which appear most frequently in the 1 to 10 kc/s range. Polar chorus, in the range 500 cps to 1000 cps, and auroral hiss, appearing above 4 kc/s, are less likely to be observed simultaneously at conjugate points. "Periodic" emissions appear alternately in opposite hemispheres and may or may not show dispersion. Their similarity in strength and spectral shape as observed at conjugate points indicates that they are produced by a mechanism that is equally effective in both directions. It has been suggested that the transverse resonance instability operating with trapped electrons at the top of the path may account for periodic emissions. Quasi-periodic (QP) emissions (also called long-period pulsations) on the other hand appear approximately in-phase at conjugate points, suggesting modulation of the emission process by an external agency, such as hydromagnetic waves. In some cases, QP emissions are found to consist of two bands of periodic emissions that interact in such a way as to account for the observed modulation of intensity and spectral shape. Conjugate VLF emission phenomena show promise of providing new data on energetic particle streams and on the properties of the ambient propagation medium
Experiments A17 /OGO 1/ and B17 /OGO 3/ Final report, 16 Feb. 1962 - 30 Jun. 1968
VLF experiments flown on OGO 1 /A17/ and OGO 3 /B17/ including orbits and attitudes of both satellite
Modelling nitrogen dynamics at Lochnagar, N.E. Scotland.
International audienceControls on nitrate leaching from upland moorland catchments are not yet fully understood and yet, despite agreements on emission reductions, increased surface water nitrate concentrations may affect significantly the acidity status of these waters in the future. At Lochnagar, an upland moorland catchment in N.E. Scotland, 12 years of surface water chemistry observations have identified a steady increase in nitrate concentration despite no measured change in inorganic nitrogen deposition. The MAGIC model has been applied to simulate a "best case" situation assuming nitrate in surface water represents "hydrological" contributions (direct run-off) and a ?worst case' assuming a nitrogen saturation mechanism in the catchment soil. Only the ?saturation' model is capable of matching the 12 years of observation for nitrate but both model structures match the pH and acid neutralising capacity record. Future predictions to 2040, in response to the agreed emission reductions under the Gothenburg Protocol, are markedly different. The worst case predicts continued surface water acidification whilst the best case predicts a steady recovery. Keywords: nitrogen saturation, modelling, Lochnagar, Gothenburg Protoco
NGO perspectives on the social and ethical dimensions of plant genome-editing
Plant genome editing has the potential to become another chapter in the intractable debate that has dogged agricultural biotechnology. In 2016, 107 Nobel Laureates accused Greenpeace of emotional and dogmatic campaigning against agricultural biotechnology and called for governments to defy such campaigning. The Laureates invoke the authority of science to argue that Greenpeace is putting lives at risk by opposing agricultural biotechnology and Golden Rice and is notable in framing Greenpeace as unethical and its views as marginal. This paper examines environmental, food and farming NGOs’ social and ethical concerns about genome editing, situating these concerns in comparison to alternative ethical assessments provided by the Nuffield Council on Bioethics, a key actor in this policy debate. In doing so, we show that participant NGOs and the Nuffield Council on Bioethics share considerable concerns about the social and ethical implications of genome editing. These concerns include choices over problem/solution framing and broader terminology, implications of regulatory and research choices on consumer choice and relations of power. However, GM-engaged NGOs and the Nuffield Council on Bioethics diverge on one important area: the NGOs seek to challenge the existing order and broaden the scope of debate to include deeply political questions regarding agricultural and technological choices. This distinction between the ethical positions means that NGOs provide valuable ethical insight and a useful lens to open up debate and discussion on the role of emerging technologies, such as genome editing, and the future of agriculture and food sovereignty
Quantum healing of classical singularities in power-law spacetimes
We study a broad class of spacetimes whose metric coefficients reduce to
powers of a radius r in the limit of small r. Among these four-parameter
"power-law" metrics we identify those parameters for which the spacetimes have
classical singularities as r approaches 0. We show that a large set of such
classically singular spacetimes is nevertheless nonsingular quantum
mechanically, in that the Hamiltonian operator is essentially self-adjoint, so
that the evolution of quantum wave packets lacks the ambiguity associated with
scattering off singularities. Using these metrics, the broadest class yet
studied to compare classical with quantum singularities, we explore the
physical reasons why some that are singular classically are "healed" quantum
mechanically, while others are not. We show that most (but not all) of the
remaining quantum-mechanically singular spacetimes can be excluded if either
the weak energy condition or the dominant energy condition is invoked, and we
briefly discuss the effect of this work on the strong cosmic censorship
hypothesis.Comment: 14 pages, 1 figure; extensive revision
The crystal structure analysis of the relative binding of cisplatin and carboplatin in a mixture with histidine in a protein studied at 100 and 300 K with repeated X-ray irradiation
Carboplatin binding to a model protein in non-NaCl conditions to eliminate partial conversion to cisplatin, and the use of different criteria to choose the resolution limit
Hen egg white lysozyme (HEWL) co-crystallisation conditions of carboplatin
without sodium chloride (NaCl) have been utilised to eliminate partial
conversion of carboplatin to cisplatin observed previously. Tetragonal HEWL
crystals were successfully obtained in 65% MPD with 0.1M citric acid buffer at
pH 4.0 including DMSO. The X-ray diffraction data resolution to be used for the
model refinement was reviewed using several topical criteria together. The
CC1/2 criterion implemented in XDS led to data being significant to 2.0{\AA},
compared to the data only being able to be processed to 3.0{\AA} using the
Bruker software package (SAINT). Then using paired protein model refinements
and DPI values based on the FreeR value, the resolution limit was fine tuned to
be 2.3{\AA}. Interestingly this was compared with results from the EVAL
software package which gave a resolution limit of 2.2{\AA} solely using
crossing 2, but 2.8{\AA} based on the Rmerge values (60%). The
structural results showed that carboplatin bound to only the N{\delta} binding
site of His-15 one week after crystal growth, whereas five weeks after crystal
growth, two molecules of carboplatin are bound to the His-15 residue. In
summary several new results have emerged: - firstly non-NaCl conditions showed
a carboplatin molecule bound to His-15 of HEWL; secondly binding of one
molecule of carboplatin was seen after one week of crystal growth and two
molecules were bound after five weeks of crystal growth; and thirdly the use of
several criteria to determine the diffraction resolution limit led to the
successful use of data to higher resolution.Comment: 14 pages; submitted to Acta Cryst D Biological Crystallography
reference number tz504
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