659 research outputs found
An Analysis of Early Software Reliability Improvement Techniques
This research explores early life cycle software reliability prediction models or techniques to predict the reliability of software prior to writing code, and a method for increasing or improving the reliability of software products early in the development life cycle. Five prediction models and two development techniques are examined. Each model is statically analyzed in terms of availability of data early in the life cycle, ease of data collection, and whether data is currently collected. One model and the two techniques satisfied those requirements and are further analyzed for their ability to predict or improve software reliability. While the researchers offer no significant statistical results of the model\u27s ability to predict software reliability, important conclusions are drawn about the cost and time savings of using inspections as a means of improving software reliability. The results indicate that the current software development paradigm needs to be changed to use the Cleanroom Software Development Process for fixture software development. This proactive approach to developing reliable software saves development and testing costs. One obvious benefit of this research is that cost savings realized earlier in the software development cycle have a dramatic effect on making software development practices better and more efficient
Electronic structure investigation of CoO by means of soft X-ray scattering
The electronic structure of CoO is studied by resonant inelastic soft X-ray
scattering spectroscopy using photon energies across the Co 2p absorption
edges. The different spectral contributions from the energy-loss structures are
identified as Raman scattering due to d-d and charge-transfer excitations. For
excitation energies close to the L3 resonance, the spectral features are
dominated by quartet-quartet and quartet-doublet transitions of the 3d7
configuration. At excitation energies corresponding to the satellites in the Co
2p X-ray absorption spectrum of CoO, the emission features are instead
dominated by charge-transfer transitions to the 3d8L-1 final state. The spectra
are interpreted and discussed with the support of simulations within the single
impurity Anderson model with full multiplet effects which are found to yield
consistent spectral functions to the experimental data.Comment: 8 pages, 2 figures, 2 tables,
http://link.aps.org/doi/10.1103/PhysRevB.65.20510
A High-Resolution Study of the HI Content of Local Group Dwarf Irregular Galaxy WLM
Dwarf irregular galaxies are unique laboratories for studying the interaction
between stars and the interstellar medium in low mass environments. We present
the highest spatial resolution observations to date of the neutral hydrogen
content of the Local Group dwarf irregular galaxy WLM. We find that WLM's
neutral hydrogen distribution is typical for a galaxy of its type and size and
derive an HI mass of 6.3e7 Msun for WLM. In addition, we derive an HI extent
for WLM of 30 arcmin, which is much less than the 45 arcmin extent found by
Huchtmeier, Seiradakis, and Materne (1981). We show that the broken ring of
high column density neutral hydrogen surrounding the center of WLM is likely
the result of star formation propagating out from the center of the galaxy. The
young stars and Ha emission in this galaxy are mostly correlated with the high
column density neutral hydrogen. The gap in the central ring is the result of
star formation in that region using up, blowing out, or ionizing all of the
neutral hydrogen. Like many late-type galaxies, WLM's velocity field is
asymmetric with the approaching (northern) side appearing to be warped and a
steeper velocity gradient for the approaching side than for the receding side
in the inner region of the galaxy. We derive a dynamical mass for WLM of 2.16e9
Msun.Comment: 38 pages, 15 figures, 5 tables, accepted by AJ, high resolution
version at http://www.astro.wisc.edu/~kepley/kepley_wlm.p
Competition between decay and dissociation of core-excited OCS studied by X-ray scattering
We show the first evidence of dissociation during resonant inelastic soft
X-ray scattering. Carbon and oxygen K-shell and sulfur L-shell resonant and
non-resonant X-ray emission spectra were measured using monochromatic
synchrotron radiation for excitation and ionization. After sulfur, L2,3 ->
{\pi}*, {\sigma}* excitation, atomic lines are observed in the emission spectra
as a consequence of competition between de-excitation and dissociation. In
contrast the carbon and oxygen spectra show weaker line shape variations and no
atomic lines. The spectra are compared to results from ab initio calculations
and the discussion of the dissociation paths is based on calculated potential
energy surfaces and atomic transition energies.Comment: 12 pages, 6 pictures, 2 tables,
http://link.aps.org/doi/10.1103/PhysRevA.59.428
VII Zw 403: H I structure in a blue compact dwarf galaxy
‘In these times, during the rise in the popularity of institutional repositories, the Society does not forbid authors from depositing their work in such repositories. However, the AAS regards the deposit of scholarly work in such repositories to be a decision of the individual scholar, as long as the individual's actions respect the diligence of the journals and their reviewers.’ Original article can be found at : http://iopscience.iop.org/ Copyright American Astronomical SocietyWe present optical (UBVJ), ultraviolet (FUV, NUV), and high-resolution atomic hydrogen (H I) observations of the nearby blue compact dwarf (BCD), VII Zw 403. We find that VII Zw 403 has a relatively high H I mass-to-light ratio for a BCD. The rotation velocity is nominally 10-15 km s(-1), but rises to similar to 20 km s(-1) after correction for the similar to 8-10 km s(-1) random motions present in the gas. The velocity field is complex, including a variation in the position angle of the major axis going from the northeast to the southwest parts of the galaxy. Our high-resolution Hi maps reveal structure in the central gas, including a large, low-density Hi depression or hole between the southern and northern halves of the galaxy, coincident with an unresolved X-ray source. Although interactions have been proposed as the triggering mechanism for the vigorous star formation occurring in BCDs, VII Zw 403 does not seem to have been tidally triggered by an external interaction, as we have found no nearby possible perturbers. It also does not appear to fall in the set of galaxies that exhibit a strong central mass density concentration, as its optical scale length is large in comparison to similar systems. However, there are some features that are compatible with an accretion event: optical/Hi axis misalignment, a change in position angle of the kinematic axis, and a complex velocity field.Peer reviewe
Resonant soft X-ray Raman scattering of NiO
Resonant soft X-ray Raman scattering measurements on NiO have been made at
photon energies across the Ni 2p absorption edges. The details of the spectral
features are identified as Raman scattering due to d-d and charge-transfer
excitations. The spectra are interpreted within the single impurity Anderson
model, including multiplets, crystal-field and charge-transfer effects. At
threshold excitation, the spectral features consists of triplet-triplet and
triplet-singlet transitions of the 3d8 configuration. For excitation energies
corresponding to the charge-transfer region in the Ni 2p X-ray absorption
spectrum of NiO, the emission spectra are instead dominated by charge-transfer
transitions to the 3d9L-1 final state. Comparisons of the final states with
other spectroscopical techniques are also made.Comment: 9 pages, 2 figures, 2 tables,
http://iopscience.iop.org/0953-8984/14/13/32
Electronic structure investigation of CeB6 by means of soft X-ray scattering
The electronic structure of the heavy fermion compound CeB6 is probed by
resonant inelastic soft X-ray scattering using photon energies across the Ce 3d
and 4d absorption edges. The hybridization between the localized 4f orbitals
and the delocalized valence-band states is studied by identifying the different
spectral contributions from inelastic Raman scattering and normal fluorescence.
Pronounced energy-loss structures are observed below the elastic peak at both
the 3d and 4d thresholds. The origin and character of the inelastic scattering
structures are discussed in terms of charge-transfer excitations in connection
to the dipole allowed transitions with 4f character. Calculations within the
single impurity Anderson model with full multiplet effects are found to yield
consistent spectral functions to the experimental data.Comment: 9 pages, 4 figures, 1 table,
http://link.aps.org/doi/10.1103/PhysRevB.63.07510
Dic(9;20)(p13;q11) in childhood acute lymphoblastic leukaemia is related to low cellular resistance to asparaginase, cytarabine and corticosteroids.
To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldDic(9;20)(p13;q11) was first described as a nonrandom chromosome abnormality in B-cell precursor acute lymphoblastic leukaemia (BCP ALL) in the mid 1990s,1, 2 and 71 dic(9;20)-positive cases have since then been reported.3, 4, 5 Approximately 90% of these cases were children or adolescents, with dic(9;20) occurring in about 2% of childhood BCP ALL.6 The recent review by Forestier et al.5 describes that dic(9;20)-leukaemias are of B-cell precursor immunophenotype, never have a high hyperdiploid modal number, show a female predominance, and have a significant age incidence peak at 3 years. Most patients are allocated to non-standard risk treatment arms due to high WBC (median 24 109/l) and a relatively high frequency of CNS disease or other extra-medullary leukaemia (EML) at diagnosis. The prognostic implications of dic(9;20) are to a large extent unknown. A relatively large proportion of the relapses reported in the literature have been extra-medullary, and post-relapse treatment including block therapy has been successful in several patients, as illustrated by a p-EFS of 0.62 and a predicted overall survival of 0.82 at 5 years for the 24 Nordic cases.
- …