53,058 research outputs found
Coaxial cable stripping device facilitates RF cabling fabrication
Coaxial cable stripping device assures clean, right angled shoulder for RF cable connector fabrication. This method requires minimal skill and creates a low voltage standing wave ratio and mechanical stability in the interconnecting RF Cables
GpsTunes: controlling navigation via audio feedback
We combine the functionality of a mobile Global Positioning System (GPS) with that of an MP3 player, implemented on a PocketPC, to produce a handheld system capable of guiding a user to their desired target location via continuously adapted music feedback. We illustrate how the approach to presentation of the audio display can benefit from insights from control theory, such as predictive 'browsing' elements to the display, and the appropriate representation of uncertainty or ambiguity in the display. The probabilistic interpretation of the navigation task can be generalised to other context-dependent mobile applications. This is the first example of a completely handheld location- aware music player. We discuss scenarios for use of such systems
Charged spin 1/2 particle in an arbitrary magnetic field in two spatial dimensions: a supersymmetric quantum mechanical system
It is shown that the 2 X 2 matrix Hamiltonian describing the dynamics of a
charged spin 1/2 particle with g-factor 2 moving in an arbitrary, spatially
dependent, magnetic field in two spatial dimensions can be written as the
anticommuator of a nilpotent operator and its hermitian conjugate.
Consequently, the Hamiltonians for the two different spin projections form
partners of a supersymmetric quantum mechanical system. The resulting
supersymmetry algebra can then be exploited to explicitly construct the exact
zero energy ground state wavefunction for the system. Modulo this ground state,
the remainder of the eigenstates and eigenvalues of the two partner
Hamiltonians form positive energy degenerate pairs. We also construct the
spatially asymptotic form of the magnetic field which produces a finite
magnetic flux and associated zero energy normalizable ground state
wavefunction.Comment: 10 pages, LaTe
Recent integral cross section validation measurements at the ASP facility
This work presents new integral data measured at the ASP 14 MeV neutron
irradiation facility at Aldermaston in the UK, which has recently become
available for fusion-related work through the CCFE materials programme.
Measurements of reaction products from activation experiments using elemental
foils were carried out using gamma spectrometry in a high efficiency,
high-purity germanium (HPGe) detector and associated digital signal processing
hardware. Following irradiation and rapid extraction to the measurement cell,
gamma emissions were acquired with both energy and time bins. Integral cross
section and half-life data have been derived from these measurements. Selected
integral cross section values are presented from the measurement campaigns.Comment: 4 pages, 5 figure
Meteoroid detector
A meteoroid detector is described which uses, a cold cathode discharge tube with a gas-pressurized cell in space for recording a meteoroid puncture of the cell and for determining the size of the puncture
On the origin of <i>Halipeurus heraldicus</i> on Round Island petrels: cophylogenetic relationships between petrels and their chewing lice
Lice phylogenetic relationships have often been used to elucidate host relationships and vice versa. In this study, we investigate the louse genus Halipeurus which parasitizes bird hosts in the families Procellariidae, Hydrobatidae and Pelecanoididae. The presence of two lice species on Pterodroma arminjoniana in different breeding grounds (Halipeurus heraldicus on Round Island, off Mauritius in the Indian Ocean and Halipeurus kermadecensis on Trindade Island in the Atlantic Ocean) has led to some confusion in the distribution of Pt. arminjoniana and its close relatives Pt. heraldica and Pt. neglecta. By using a cophylogenetic approach that incorporates uncertainties in phylogenetic reconstructions, we show significant overall coevolution between Halipeurus lice and their hosts. However, the study also indicates that the presence of H. heraldicus on Pt. arminjoniana and Pt. neglecta on Round Island and on Pt. heraldica on Gambier Island are the result of a host switch whereas H. kermadecensis is the ancestral parasite of Pt. arminjoniana. This suggests that H. kermadecensis was lost during or after colonisation of Round Island by Pt. arminjoniana. We conclude that cophylogenetic analyses are central to inferring the evolutionary history and biogeographical patterns of hosts and their parasites
A search for X-ray polarization in cosmic X-ray sources
Fifteen strong X-ray sources were observed by the X-ray polarimeters on board the OSO-8 satellite from 1975 to 1978. The final results of this search for X-ray polarization in cosmic sources are presented in the form of upper limits for the ten sources which are discussed elsewhere. These limits in all cases are consistent with a thermal origin for the X-ray emission
Double-impulse magnetic focusing of launched cold atoms.
We have theoretically investigated three-dimensional focusing of a launched cloud of cold atoms using a pair of magnetic lens pulses (the alternate-gradient method). Individual lenses focus radially and defocus axially or vice versa. The performance of the two possible pulse sequences are compared and found to be ideal for loading both 'pancake' and 'sausage' shaped magnetic/optical microtraps. It is shown that focusing aberrations are considerably smaller for double-impulse magnetic lenses compared to single-impulse magnetic lenses. An analysis of clouds focused by the double-impulse technique is presented
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