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Disease modelling using evolved discriminate function
Precocious diagnosis increases the survival time and patient quality of life. It is a binary classification, exhaustively studied in the literature. This paper innovates proposing the application of genetic programming to obtain a discriminate function. This function contains the disease dynamics used to classify the patients with as little false negative diagnosis as possible. If its value is greater than zero then it means that the patient is ill, otherwise healthy. A graphical representation is proposed to show the influence of each dataset attribute in the discriminate function. The experiment deals with Breast Cancer and Thrombosis & Collagen diseases diagnosis. The main conclusion is that the discriminate function is able to classify the patient using numerical clinical data, and the graphical representation displays patterns that allow understanding of the model
The hot white dwarf in the peculiar binary nucleus of the planetary nebula EGB6
EGB6 is an extended, faint old planetary nebula (PN) with an enigmatic
nucleus. The central star (PG0950+139) is a hot DAOZ-type white dwarf (WD). An
unresolved, compact emission knot was discovered to be located 0.166" away from
the WD and it was shown to be centered around a dust-enshrouded low-luminosity
star. It was argued that the dust disk and evaporated gas (photoionized by the
hot WD) around the companion are remnants of a disk formed by wind material
captured from the WD progenitor when it was an asymptotic giant branch (AGB)
star. In this paper, we assess the hot WD to determine its atmospheric and
stellar parameters. We performed a model-atmosphere analysis of ultraviolet
(UV) and optical spectra. We found Teff = 105,000 +/- 5000 K, log g = 7.4 +/-
0.4, and a solar helium abundance (He = 0.25 +/- 0.1, mass fraction). We
measured the abundances of ten more species (C, N, O, F, Si, P, S, Ar, Fe, Ni)
and found essentially solar abundance values, indicating that radiation-driven
wind mass-loss, with a theoretical rate of log(dot-M/M_sun/yr) = -11.0
(+1.1)(-0.8) prevents the gravitational separation of elements in the
photosphere. The WD has a mass of M/M_sun = 0.58 (+0.12)(-0.04) and its
post-AGB age (log(t_evol/yr) = 3.60 (+1.26)(-0.09)) is compatible with the PN
kinematical age of log(t_PN}/yr) = 4.2. In addition, we examined the UV
spectrum of the hot nucleus of a similar object with a compact emission region,
TOL26 (PN G298.0+34.8), and found that it is a slightly cooler DAOZ WD (Teff
about 85,000 K), but this WD shows signatures of gravitational settling of
heavy elements.Comment: A&A accepte
Metal abundances in hot white dwarfs with signatures of a superionized wind
About a dozen hot white dwarfs with effective temperatures Teff =
65,000-120,000 K exhibit unusual absorption features in their optical spectra.
These objects were tentatively identified as Rydberg lines of ultra-high
excited metals in ionization stages V-X, indicating line formation in a dense
environment with temperatures near one million Kelvin. Since some features show
blueward extensions, it was argued that they stem from a superionized wind. A
unique assignment of the lines to particular elements is not possible, although
they probably stem from C, N, O, and Ne. To further investigate this
phenomenon, we analyzed the ultraviolet spectra available from only three stars
of this group; that is, two helium-rich white dwarfs, HE 0504-2408 and HS
0713+3958 with spectral type DO, and a hydrogen-rich white dwarf, HS 2115+1148
with spectral type DAO. We identified light metals (C, N, O, Si, P, and S) with
generally subsolar abundances and heavy elements from the iron group (Cr, Mn,
Fe, Co, Ni) with solar or oversolar abundance. The abundance patterns are not
unusual for hot WDs and can be interpreted as the result of gravitational
settling and radiative levitation of elements. As to the origin of the
ultra-high ionized metals lines, we discuss the possible presence of a
multicomponent radiatively driven wind that is frictionally heated.Comment: Accepted for publication in A&
The far-ultraviolet spectra of two hot PG1159 stars
PG1159 stars are hot, hydrogen-deficient (pre-) white dwarfs with atmospheres
mainly composed of helium, carbon, and oxygen. The unusual surface chemistry is
the result of a late helium-shell flash. Observed element abundances enable us
to test stellar evolution models quantitatively with respect to their
nucleosynthesis products formed near the helium-burning shell of the progenitor
asymptotic giant branch stars. Because of the high effective temperatures
(Teff), abundance determinations require ultraviolet spectroscopy and non-local
thermodynamic equilibrium model atmosphere analyses. Up to now, we have
presented results for the prototype of this spectral class and two cooler
members (Teff in the range 85,000-140,000 K). Here we report on the results for
two even hotter stars (PG1520+525 and PG1144+005, both with Teff = 150,000 K)
which are the only two objects in this temperature-gravity region for which
useful far-ultraviolet spectra are available, and revisit the prototype star.
Previous results on the abundances of some species are confirmed, while results
on others (Si, P, S) are revised. In particular, a solar abundance of sulphur
is measured in contrast to earlier claims of a strong S deficiency that
contradicted stellar evolution models. For the first time, we assess the
abundances of Na, Al, and Cl with newly constructed non-LTE model atoms.
Besides the main constituents (He, C, O), we determine the abundances (or upper
limits) of N, F, Ne, Na, Al, Si, P, S, Cl, Ar, and Fe. Generally, good
agreement with stellar models is found.Comment: Accepted for publication in A&
On the Relevance of Compton Scattering for the Soft X-ray Spectra of Hot DA White Dwarfs
We re-examine the effects of Compton scattering on the emergent spectra of
hot DA white dwarfs in the soft X-ray range. Earlier studies have implied that
sensitive X-ray observations at wavelengths \AA might be capable
of probing the flux deficits predicted by the redistribution of
electron-scattered X-ray photons toward longer wavelengths. We adopt two
independent numerical approaches to the inclusion of Compton scattering in the
computation of pure hydrogen atmospheres in hydrostatic equilibrium. One
employs the Kompaneets diffusion approximation formalism, while the other uses
the cross-sections and redistribution functions of Guilbert. Models and
emergent spectra are computed for stellar parameters representative of HZ 43
and Sirius B, and for models with an effective temperature K. The differences between emergent spectra computed for Compton and
Thomson scattering cases are completely negligible in the case of both HZ 43
and Sirius B models, and are also negligible for all practical purposes for
models with temperatures as high as K. Models of the
soft X-ray flux from these stars are instead dominated by uncertainties in
their fundamental parameters.Comment: 7 pages, 5 figures, accepted for publication in A&
A universally programmable Quantum Cellular Automaton
We discuss the role of classical control in the context of reversible quantum
cellular automata. Employing the structure theorem for quantum cellular
automata, we give a general construction scheme to turn an arbitrary cellular
automaton with external classical control into an autonomous one, thereby
proving the computational equivalence of these two models. We use this
technique to construct a universally programmable cellular automaton on a
one-dimensional lattice with single cell dimension 12.Comment: 4 pages, 4 figures, minor changes in introduction, fixed typos,
accepted for publication in Physical Review Letter
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