2,513 research outputs found
Migration on request, a practical technique for preservation
Maintaining a digital object in a usable state over time is a crucial aspect of digital preservation. Existing methods of preserving have many drawbacks. This paper describes advanced techniques of data migration which can be used to support preservation more accurately and cost effectively.
To ensure that preserved works can be rendered on current computer systems over time, “traditional migration” has been used to convert data into current formats. As the new format becomes obsolete another conversion is performed, etcetera. Traditional migration has many inherent problems as errors during transformation propagate throughout future transformations.
CAMiLEON’s software longevity principles can be applied to a migration strategy, offering improvements over traditional migration. This new approach is named “Migration on Request.” Migration on Request shifts the burden of preservation onto a single tool, which is maintained over time. Always returning to the original format enables potential errors to be significantly reduced
Neuromyelitis optica spectrum disorder in three generations of a Chinese family
© 2019 Neuromyelitis optica spectrum disorder is an inflammatory demyelinating disease that is largely sporadic. Familial disease has been reported in one or two generations, although its basis remains unknown. We report here three subjects meeting diagnostic criteria for NMOSD in one family: a father and son, and the maternal aunt of the father. Anticipation, of 27 years, was apparent in transmission from father to son. Aquaporin-4 antibodies were observed in the aunt but not the father and son, nor in other family members. A putative pathogenic mutation in the NECL2 gene was not found in this pedigree. This first report of NMOSD in three generations of one family underlines the heterogeneity of familial NMOSD
Field Application of a Monoclonal Antibody Panel to Differentiate Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) Isolates
Porcine reproductive and respiratory syndrome (PRRS) is recognized as the most economically devastating disease of swine throughout the world. Nucleotide sequencing and serological studies have deomnstrated sustantial antigenic variation amoung PRRS virus (PRRSV) isolates (Murtaugh, et al., 1995; Nelson, et al., 1993, 1996). Recently, European-like PRRSV isolates have been identified in the US (Rossow, et al. 2000) and other new, highly virulent PRRSV isolates have appeared and affect sows at all stages of gestation causing mortality of adult pigs as well as young pigs (Epperson et al., 1997). Therefore, it is even more important to control the spread of these new strains. Clinical signs vary between herds, indicating that viruses may differ in pathogenicity. Furthermore, effective use of vaccines and management approaches to control PRRS has not always been successful
Skyrmions in Higher Landau Levels
We calculate the energies of quasiparticles with large numbers of reversed
spins (``skyrmions'') for odd integer filling factors 2k+1, k is greater than
or equals 1. We find, in contrast with the known result for filling factor
equals 1 (k = 0), that these quasiparticles always have higher energy than the
fully polarized ones and hence are not the low energy charged excitations, even
at small Zeeman energies. It follows that skyrmions are the relevant
quasiparticles only at filling factors 1, 1/3 and 1/5.Comment: 10 pages, RevTe
Anisotropic Transport of Quantum Hall Meron-Pair Excitations
Double-layer quantum Hall systems at total filling factor can
exhibit a commensurate-incommensurate phase transition driven by a magnetic
field oriented parallel to the layers. Within the commensurate
phase, the lowest charge excitations are believed to be linearly-confined Meron
pairs, which are energetically favored to align with . In order
to investigate this interesting object, we propose a gated double-layer Hall
bar experiment in which can be rotated with respect to the
direction of a constriction. We demonstrate the strong angle-dependent
transport due to the anisotropic nature of linearly-confined Meron pairs and
discuss how it would be manifested in experiment.Comment: 4 pages, RevTex, 3 postscript figure
X-Ray-Diffraction Study of Charge-Density-Waves and Oxygen-Ordering in YBa2Cu3O6+x Superconductor
We report a temperature-dependent increase below 300 K of diffuse
superlattice peaks corresponding to q_0 =(~2/5,0,0) in an under-doped
YBa_2Cu_3O_6+x superconductor (x~0.63). These peaks reveal strong c-axis
correlations involving the CuO_2 bilayers, show a non-uniform increase below
\~220 K with a plateau for ~100-160 K, and appear to saturate in the
superconducting phase. We interpret this unconventional T-dependence of the
``oxygen-ordering'' peaks as a manifestation of a charge density wave in the
CuO_2 planes coupled to the oxygen-vacancy ordering.Comment: 4 pages, 4 figure
Thermodynamical Bethe Ansatz and Condensed Matter
The basics of the thermodynamic Bethe ansatz equation are given. The simplest
case is repulsive delta function bosons, the thermodynamic equation contains
only one unknown function. We also treat the XXX model with spin 1/2 and the
XXZ model and the XYZ model. This method is very useful for the investigation
of the low temperature thermodynamics of solvable systems.Comment: 52 pages, 6 figures, latex, lamuphys.st
Collective Excitations and Ground State Correlations
A generalized RPA formalism is presented which treats pp and ph correlations
on an equal footing. The effect of these correlations on the single-particle
Green function is discussed and it is demonstrated that a self-consistent
treatment of the single-particle Green function is required to obtain stable
solutions. A simple approximation scheme is presented which incorporates for
this self-consistency requirement and conserves the number of particles.
Results of numerical calculations are given for O using a G-matrix
interaction derived from a realistic One-Boson-Exchange potential.Comment: 16 Pages + 2 Figures (included at the end as uuencoded ps-files),
TU-18089
The effects of magnetic field on the d-density wave order in the cuprates
We consider the effects of a perpendicular magnetic field on the d-density
wave order and conclude that if the pseudogap phase in the cuprates is due to
this order, then it is highly insensitive to the magnetic field in the
underdoped regime, while its sensitivity increases as the gap vanishes in the
overdoped regime. This appears to be consistent with the available experiments
and can be tested further in neutron scattering experiments. We also
investigate the nature of the de Haas- van Alphen effect in the ordered state
and discuss the possibility of observing it.Comment: 5 pages, 4 eps figures, RevTex4. Corrected a silly but important typo
in the abstrac
- …