82,464 research outputs found
Reskilling staff for digital libraries
In academic libraries, the digital library world has had a profound impact on staffing. Academic libraries are facing huge pressure on their staffing levels at a time when digital libraries are being introduced. Digital libraries cannot be divorced from ordinary libraries. What skills do traditional librarians need? There is little in the literature on training for staffing for digital libraries. Consequently, evidence from a recent PhD gleaned from research interviews of these digital libraries case studies is included in this paper. This research uncovered a variety of different management and organizational issues and revealed the large cost of personnel in the implementation and maintenance of digital libraries
On the fate of Lorentz symmetry in relative-locality momentum spaces
The most studied doubly-special-relativity scenarios, theories with both the
speed-of-light scale and a length/inverse-momentum scale as non-trivial
relativistic invariants, have concerned the possibility of enforcing
relativistically some nonlinear laws on momentum space. For the
"relative-locality framework" recently proposed in arXiv:1101.0931 a central
role is played by nonlinear laws on momentum space, with the guiding principle
that they should provide a characterization of the geometry of momentum space.
Building on previous doubly-special-relativity results I here identify a
criterion for establishing whether or not a given geometry of the
relative-locality momentum space is "DSR compatible", i.e. compatible with an
observer-independent formulation of theories on that momentum space. I find
that given some chosen parametrization of momentum-space geometry the criterion
takes the form of an elementary algorithm. I show that relative-locality
momentum spaces that fail my criterion definitely "break" Lorentz invariance,
i.e. theories on such momentum spaces necessarily are observer-dependent
"ether" theories. By working out a few examples I provide evidence that when
the criterion is instead satisfied one does manage to produce a relativistic
formulation. The examples I use to illustrate the applicability of my criterion
also have some intrinsic interest, including two particularly noteworthy cases
of -Poincar\'e-inspired momentum spaces.Comment: 24 pages, LaTe
Comment on "Light-front Schwinger model at finite temperature"
In a recent paper by A. Das and X. Zhou [Phys. Rev. D 68, 065017 (2003)] it
is claimed that explicit evaluation of the thermal photon self-energy in the
Schwinger model gives off-shell thermal Green functions that are different in
light-front and conventional quantizations. We show that the claimed difference
originates from an erroneous simplification of the fermion propagator used in
the light-front calculation.Comment: 8 pages, revtex4, added section refuting the massless limit proposed
in hep-th/031102
Interferometry of hyper-Rayleigh scattering by inhomogeneous thin films
The use of specific symmetry properties of the optical second-harmonic
generation (the s,s-exclusion rule) has allowed us to observe high-contrast
hyper-Rayleigh interference patterns in a completely diffuse light - an effect
having no analog in case of linear (Rayleigh) scattering.Comment: 8 pages, 3 figure
Theoretical studies of space plasmas Summary report, 3 May 1965 - 1 May 1966
Synchrotron radiation, ionospheric currents, auroral bombardment, and plasma instabilitie
The impact of satellite temperature soundings on the forecasts of a small national meteorological service
The impact of introducing satellite temperature sounding data on a numerical weather prediction model of a national weather service is evaluated. A dry five level, primitive equation model which covers most of the Northern Hemisphere, is used for these experiments. Series of parallel forecast runs out to 48 hours are made with three different sets of initial conditions: (1) NOSAT runs, only conventional surface and upper air observations are used; (2) SAT runs, satellite soundings are added to the conventional data over oceanic regions and North Africa; and (3) ALLSAT runs, the conventional upper air observations are replaced by satellite soundings over the entire model domain. The impact on the forecasts is evaluated by three verification methods: the RMS errors in sea level pressure forecasts, systematic errors in sea level pressure forecasts, and errors in subjective forecasts of significant weather elements for a selected portion of the model domain. For the relatively short range of the present forecasts, the major beneficial impacts on the sea level pressure forecasts are found precisely in those areas where the satellite sounding are inserted and where conventional upper air observations are sparse. The RMS and systematic errors are reduced in these regions. The subjective forecasts of significant weather elements are improved with the use of the satellite data. It is found that the ALLSAT forecasts are of a quality comparable to the SAR forecasts
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