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Estimating Residual Faults from Code Coverage
Many reliability prediction techniques require an estimate for the number of residual faults. In this paper, a new theory is developed for using test coverage to estimate the number of residual faults. This theory is applied to a specific example with known faults and the results agree well with the theory. The theory is used to justify the use of linear extrapolation to estimate residual faults. It is also shown that it is important to establish the amount of unreachable code in order to make a realistic residual fault estimate
Optimal Strategies for Prudent Investors
We consider a stochastic model of investment on an asset of a stock market
for a prudent investor. She decides to buy permanent goods with a fraction \a
of the maximum amount of money owned in her life in order that her economic
level never decreases. The optimal strategy is obtained by maximizing the
exponential growth rate for a fixed \a. We derive analytical expressions for
the typical exponential growth rate of the capital and its fluctuations by
solving an one-dimensional random walk with drift.Comment: 14 pages, LaTeX, epsfig.sty, 7 eps figures, minor changes; accepted
for International J. of Theoretical and Applied Financ
The Be-test in the Li-rich star \#1657 of NGC 6397: evidence for Li-flash in RGB stars?
The Li-rich turn-off star in the globular cluster NGC 6397 could represent
the smoking gun for some very rare episode of Li enrichment in globular
clusters. We aim to understand the nature of the Li enrichment by performing a
spectroscopic analysis of the star, in particular of its beryllium (Be)
abundance, and by investigating its binary nature. We observe the near UV
region where the Beii resonance doublet and the NH bands are located. We could
not detect the Beii lines and derive an upper limit of log (Be/H)< -12.2, that
is consistent with the Be observed in other stars of the cluster. We could
detect a weak G-band, which implies a mild carbon enhancement
[C/Fe]. We could not detect the UV NH band, and we derive an upper
limit [N/Fe]. For oxygen we could notdetect any of the near UV OH lines,
which implies that oxygen cannot be strongly enhanced in this star. This is
consistent with the detection of the Oi triplet at 777nm, which is consistent
with [O/Fe]~0.5. Combining the UVES and Mike data, we could not detect any
variation in the radial velocity greater than 0.95 kms over 8 years. The
chemical composition of the star strongly resembles that of `first generation'
NGC6397 stars, with the huge Li as the only deviating abundance. Not detecting
Be rules out two possible explanations of the Li overabundance: capture of a
substellar body and spallation caused by a nearby type II SNe. Discrepancies
are also found with respect to other accretion scenarios,except for
contamination by the ejecta of a star that has undergone the RGB Li-flash.Comment: Accepted for publication in A&
Azimuthal spin asymmetries in light-cone constituent quark models
We present results for all leading-twist azimuthal spin asymmetries in
semi-inclusive lepton-nucleon deep-inelastic scattering due to T-even
transverse-momentum dependent parton distribution functions on the basis of a
light-cone constituent quark model. Attention is paid to discuss the range of
applicability of the model, especially with regard to the scale dependence of
the observables and the transverse-momentum dependence of the distributions. We
find good agreement with available experimental data and present predictions to
be further tested by future CLAS, COMPASS and HERMES data.Comment: 23 pages, 14 figures, 1 tabl
Testing LCDM with the Growth Function \delta(a): Current Constraints
We have compiled a dataset consisting of 22 datapoints at a redshift range
(0.15,3.8) which can be used to constrain the linear perturbation growth rate
f=\frac{d\ln\delta}{d\ln a}. Five of these data-points constrain directly the
growth rate f through either redshift distortions or change of the power
spectrum with redshift. The rest of the datapoints constrain f indirectly
through the rms mass fluctuation \sigma_8(z) inferred from Ly-\alpha at various
redshifts. Our analysis tests the consistency of the LCDM model and leads to a
constraint of the Wang-Steinhardt growth index \gamma (defined from
f=\Omega_m^\gamma) as \gamma=0.67^{+0.20}_{-0.17}. This result is clearly
consistent at with the value \gamma={6/11}=0.55 predicted by LCDM. A
first order expansion of the index \gamma in redshift space leads to similar
results.We also apply our analysis on a new null test of LCDM which is similar
to the one recently proposed by Chiba and Nakamura (arXiv:0708.3877) but does
not involve derivatives of the expansion rate . This also leads to the
fact that LCDM provides an excellent fit to the current linear growth data.Comment: 7 pages, 4 figures. Added comments on the data of Table I (after eq.
(2.16)). Corrected a typo on eq. (2.15). The mathematica files with the
numerical analysis of this study may be found at
http://nesseris.physics.uoi.gr/growth/growth.ht
TMDs and Azimuthal Spin Asymmetries in a Light-Cone Quark Model
The main properties of the leading-twist transverse momentum dependent parton
distributions in a light-cone constituent quark model of the nucleon are
reviewed, with focus on the role of the spin-spin and spin-orbit correlations
of quarks. Results for azimuthal single spin asymmetries in semi-inclusive deep
inelastic scattering are also discussed.Comment: Proceedings of SPIN2008, 6-11 October 2008, Charlottesville, VA, US
Transverse momentum dependent parton distributions and azimuthal asymmetries in light-cone quark models
We review the information on the spin and orbital angular momentum structure
of the nucleon encoded in the T-even transverse momentum dependent parton
distributions within light-cone quark models. Model results for azimuthal spin
asymmetries in semi-inclusive lepton-nucleon deep-inelastic scattering are
discussed, showing a good agreement with available experimental data and
providing predictions to be further tested by future CLAS, COMPASS and HERMES
data.Comment: 6 pages, 4 figures; proceedings of the "XIII Workshop On High Energy
Spin Physics Dubna Spin 2009", 1-5 September 2009, Dubna, Russi
Beaming Binaries - a New Observational Category of Photometric Binary Stars
The new photometric space-borne survey missions CoRoT and Kepler will be able
to detect minute flux variations in binary stars due to relativistic beaming
caused by the line-of-sight motion of their components. In all but very short
period binaries (P>10d), these variations will dominate over the ellipsoidal
and reflection periodic variability. Thus, CoRoT and Kepler will discover a new
observational class: photometric beaming binary stars. We examine this new
category and the information that the photometric variations can provide. The
variations that result from the observatory heliocentric velocity can be used
to extract some spectral information even for single stars.Comment: 15 pages, 4 figures, accpeted for publication in The Astrophysical
Journa
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