751 research outputs found
On the contribution of thermal excitation to the total 630.0 nm emissions in the northern cusp ionosphere
Direct impact excitation by precipitating electrons is believed to be the
main source of 630.0 nm emissions in the cusp ionosphere. However, this paper
investigates a different source, 630.0 emissions caused by thermally excited
atomic oxygen OD) when high electron temperature prevail in the cusp. On
22 January 2012 and 14 January 2013, the European Incoherent Scatter Scientific
Association (EISCAT) radar on Svalbard measured electron temperature
enhancements exceeding 3000 K near magnetic noon in the cusp ionosphere over
Svalbard. The electron temperature enhancements corresponded to electron
density enhancements exceeding m accompanied by intense 630.0
nm emissions in a field of view common to both the EISCAT Svalbard radar and a
meridian scanning photometer. This offered an excellent opportunity to
investigate the role of thermally excited OD) 630.0 nm emissions in the
cusp ionosphere. The thermal component was derived from the EISCAT Radar
measurements and compared with optical data. For both events the calculated
thermal component had a correlation coefficient greater than 0.8 to the total
observed 630.0 nm intensity which contains both thermal and particle impact
components. Despite fairly constant solar wind, the calculated thermal
component intensity fluctuated possibly due to dayside transients in the
aurora
Sensors in your clothes: Design and development of a prototype
Wearable computing is fast advancing as a preferred approach for integrating software solutions not only in our environment, but also in our everyday garments to exploit the numerous information sources we constantly interact with. This paper explores this context further by showing the possible use of wearable sensor technology for information critical information systems, through the design and development of a proof-of-concept prototyp
Identification and quantification of sites of nitration and oxidation in the key matrix protein laminin and the structural consequences of these modifications
Biocatalytic preparation and absolute configuration of enantiomerically pure fungistatic anti-2-benzylindane derivatives. Study of the detoxification mechanism by Botrytis cinerea
Enantiomerically pure 2-benzylindane derivatives were prepared using biocatalytic methods and their
absolute configuration determined. (1R,2S)-2-Benzylindan-1-ol ((1R,2S)-2) and
(S)-2-benzylindan-1-one ((S)-3) were produced by fermenting bakerâs yeast. Lipase-mediated
esterifications and hydrolysis of the corresponding racemic substrates gave rise to the enantiopure
compounds (1S,2R)-2-benzylindan-1-ol ((1S,2R)-2) and (1R,2S)-2-benzylindan-1-ol ((1R,2S)-2),
respectively. The antifungal activity of these products against two strains of the plant pathogen Botrytis
cinerea was tested. The metabolism of anti-(±)-2-benzylindan-1-ol (anti-(±)-2) by B. cinerea as part of
the fungal detoxification mechanism is also described and revealed interesting differences in the genome
of both strains
Non-triggered auroral substorms and long-period (1â4 mHz) geomagnetic and auroral luminosity pulsations in the polar cap
A study is undertaken into parameters of the polar auroral and geomagnetic pulsations in the frequency range 1â4âŻmHz (Pc5âPi3) during quiet geomagnetic intervals preceding auroral substorms and non-substorm background variations. Special attention is paid to substorms that occur under parameters of the interplanetary magnetic field (IMF) conditions typical for undisturbed days (ânon-triggered substormsâ). The spectral parameters of pulsations observed in auroral luminosity as measured by a meridian scanning photometer (Svalbard) in the polar cap and near the polar boundary of the auroral oval are studied and compared with those for the geomagnetic pulsations measured by the magnetometer network IMAGE in the same frequency range. It is found that Pc5âPi3 power spectral density (PSD) is higher during pre-substorm time intervals than for non-substorm days and that specific variations of pulsation parameters (âsubstorm precursorsâ) occur during the last 2â4 pre-substorm hours
An integrated 4249 marker FISH/RH map of the canine genome
BACKGROUND: The 156 breeds of dog recognized by the American Kennel Club offer a unique opportunity to map genes important in genetic variation. Each breed features a defining constellation of morphological and behavioral traits, often generated by deliberate crossing of closely related individuals, leading to a high rate of genetic disease in many breeds. Understanding the genetic basis of both phenotypic variation and disease susceptibility in the dog provides new ways in which to dissect the genetics of human health and biology. RESULTS: To facilitate both genetic mapping and cloning efforts, we have constructed an integrated canine genome map that is both dense and accurate. The resulting resource encompasses 4249 markers, and was constructed using the RHDF5000-2 whole genome radiation hybrid panel. The radiation hybrid (RH) map features a density of one marker every 900 Kb and contains 1760 bacterial artificial chromosome clones (BACs) localized to 1423 unique positions, 851 of which have also been mapped by fluorescence in situ hybridization (FISH). The two data sets show excellent concordance. Excluding the Y chromosome, the map features an RH/FISH mapped BAC every 3.5 Mb and an RH mapped BAC-end, on average, every 2 Mb. For 2233 markers, the orthologous human genes have been established, allowing the identification of 79 conserved segments (CS) between the dog and human genomes, dramatically extending the length of most previously described CS. CONCLUSIONS: These results provide a necessary resource for the canine genome mapping community to undertake positional cloning experiments and provide new insights into the comparative canine-human genome maps
Exact and quasiexact solvability of second-order superintegrable quantum systems: I. Euclidean space preliminaries
We show that second-order superintegrable systems in two-dimensional and three-dimensional Euclidean space generate both exactly solvable (ES) and quasiexactly solvable (QES) problems in quantum mechanics via separation of variables, and demonstrate the increased insight into the structure of such problems provided by superintegrability. A principal advantage of our analysis using nondegenerate superintegrable systems is that they are multiseparable. Most past separation of variables treatments of QES problems via partial differential equations have only incorporated separability, not multiseparability. Also, we propose another definition of ES and QES. The quantum mechanical problem is called ES if the solution of Schrödinger equation can be expressed in terms of hypergeometric functions mFn and is QES if the Schrödinger equation admits polynomial solutions with coefficients necessarily satisfying a three-term or higher order of recurrence relations. In three dimensions we give an example of a system that is QES in one set of separable coordinates, but is not ES in any other separable coordinates. This example encompasses Ushveridze's tenth-order polynomial QES problem in one set of separable coordinates and also leads to a fourth-order polynomial QES problem in another separable coordinate set
Effect of shot peening on the residual stress and mechanical behaviour of low-temperature and high-temperature annealed martensitic gear steel 18CrNiMo7-6
A martensitic gear steel (18CrNiMo7-6) was annealed at 180 \ub0C for 2h and at ⌠750 \ub0C for 1h to design two different starting microstructures for shot peening. One maintains the original as-transformed martensite while the other contains irregular-shaped sorbite together with ferrite. These two materials were shot peened using two different peening conditions. The softer sorbite + ferrite microstructure was shot peened using 0.6 mm conditioned cut steel shots at an average speed of 25 m/s in a conventional shot peening machine, while the harder tempered martensite steel was shot peened using 1.5 mm steel shots at a speed of 50 m/s in an in-house developed shot peening machine. The shot speeds in the conventional shot peening machine were measured using an in-house lidar set-up. The microstructure of each sample was characterized by optical and scanning electron microscopy, and the mechanical properties examined by microhardness and tensile testing. The residual stresses were measured using an Xstress 3000 G2R diffractometer equipped with a Cr Kα x-ray source. The correspondence between the residual stress profile and the gradient structure produced by shot peening, and the relationship between the microstructure and strength, are analyzed and discussed
Continued fraction representation of the Coulomb Green's operator and unified description of bound, resonant and scattering states
If a quantum mechanical Hamiltonian has an infinite symmetric tridiagonal
(Jacobi) matrix form in some discrete Hilbert-space basis representation, then
its Green's operator can be constructed in terms of a continued fraction. As an
illustrative example we discuss the Coulomb Green's operator in
Coulomb-Sturmian basis representation. Based on this representation, a quantum
mechanical approximation method for solving Lippmann-Schwinger integral
equations can be established, which is equally applicable for bound-, resonant-
and scattering-state problems with free and Coulombic asymptotics as well. The
performance of this technique is illustrated with a detailed investigation of a
nuclear potential describing the interaction of two particles.Comment: 7 pages, 4 ps figures, revised versio
- âŠ