176 research outputs found
Dyonic Kerr-Newman black holes, complex scalar field and Cosmic Censorship
We construct a gedanken experiment, in which a weak wave packet of the
complex massive scalar field interacts with a four-parameter (mass, angular
momentum, electric and magnetic charges) Kerr-Newman black hole. We show that
this interaction cannot convert an extreme the black hole into a naked
sigularity for any black hole parameters and any generic wave packet
configuration. The analysis therefore provides support for the weak cosmic
censorship conjecture.Comment: Refined emphasis on the weak cosmic censorship conjecture,
conclusions otherwise unchanged. Also, two sections merged, literature review
updated, references added, a few typos correcte
All "static" spherically symmetric perfect fluid solutions of Einstein's equations with constant equation of state parameter and finite-polynomial "mass function"
We look for "static" spherically symmetric solutions of Einstein's Equations
for perfect fluid source with equation of state . In order to include
the possibilities of recently popularized dark energy and phantom energy
possibly pervading the spacetime, we put no constraints on the constant . We
consider all four cases compatible with the standard ansatz for the line
element, discussed in previous work. For each case we derive the equation
obeyed by the mass function or its analogs. For these equations, we find {\em
all} finite-polynomial solutions, including possible negative powers.
For the standard case, we find no significantly new solutions, but show that
one solution is a static phantom solution, another a black hole-like solution.
For the dynamic and/or tachyonic cases we find, among others, dynamic and
static tachyonic solutions, a Kantowski-Sachs (KS) class phantom solution,
another KS-class solution for dark energy, and a second black hole-like
solution.
The black hole-like solutions feature segregated normal and tachyonic matter,
consistent with the assertion of previous work. In the first black hole-like
solution, tachyonic matter is inside the horizon, in the second, outside.
The static phantom solution, a limit of an old one, is surprising at first,
since phantom energy is usually associated with super-exponential expansion.
The KS-phantom solution stands out since its "mass function" is a ninth order
polynomial.Comment: 24 standard LaTeX pages, 4 tables, no figures. -Title changed to
avoid equation in title. -The set of solutions and their interpretation
remains unchanged, but new classification of solutions (solution labels also
changed), consolidation of appendix into a table (omitting calculation
details) resulted in shorter paper. -Updated Publication info for preprints
in Reference
Associations between diurnal preference, sleep quality and externalizing behaviours: a behavioural genetic analysis
Background - Certain aspects of sleep co-occur with externalizing behaviours in youth, yet little is known about these associations in adults. The present study: (1) examines the associations between diurnal preference (morningness versus eveningness), sleep quality and externalizing behaviours; (2) explores the extent to which genetic and environmental influences are shared between or are unique to these phenotypes; (3) examines the extent to which genetic and environmental influences account for these associations.
Method - Questionnaires assessing diurnal preference, sleep quality and externalizing behaviours were completed by 1556 young adult twins and siblings.
Results - A preference for eveningness and poor sleep quality were associated with greater externalizing symptoms [r=0.28 (95% CI 0.23–0.33) and 0.34 (95% CI 0.28–0.39), respectively]. A total of 18% of the genetic influences on externalizing behaviours were shared with diurnal preference and sleep quality and an additional 14% were shared with sleep quality alone. Non-shared environmental influences common to the phenotypes were small (2%). The association between diurnal preference and externalizing behaviours was mostly explained by genetic influences [additive genetic influence (A)=80% (95% CI 0.56–1.01)], as was the association between sleep quality and externalizing behaviours [A=81% (95% CI 0.62–0.99)]. Non-shared environmental (E) influences accounted for the remaining variance for both associations [E=20% (95% CI −0.01 to 0.44) and 19% (95% CI 0.01–0.38), respectively].
Conclusions - A preference for eveningness and poor sleep quality are moderately associated with externalizing behaviours in young adults. There is a moderate amount of shared genetic influences between the phenotypes and genetic influences account for a large proportion of the association between sleep and externalizing behaviours. Further research could focus on identifying specific genetic polymorphisms common to both sleep and externalizing behaviours
The Dirac Equation Is Separable On The Dyon Black Hole Metric
Using the tetrad formalism, we carry out the separation of variables for the
massive complex Dirac equation in the gravitational and electromagnetic field
of a four-parameter (mass, angular momentum, electric and magnetic charges)
black hole.Comment: 13 page
The standard "static" spherically symmetric ansatz with perfect fluid source revisited
Considering the standard "static" spherically symmetric ansatz ds2 = -B(r)
dt2 + A(r) dr2 + r2 dOmega2 for Einstein's Equations with perfect fluid source,
we ask how we can interpret solutions where A(r) and B(r) are not positive, as
they must be for the static matter source interpretation to be valid.
Noting that the requirement of Lorentzian signature implies A(r) B(r) >0, we
find two possible interpretations:
(i) The nonzero component of the source four-velocity does not have to be u0.
This provides a connection from the above ansatz to the Kantowski-Sachs (KS)
spacetimes.
(ii) Regions with negative A(r) and B(r) of "static" solutions in the
literature must be interpreted as corresponding to tachyonic source.
The combinations of source type and four-velocity direction result in four
possible cases. One is the standard case, one is identical to the KS case, and
two are tachyonic. The dynamic tachyonic case was anticipated in the
literature, but the static tachyonic case seems to be new. We derive
Oppenheimer-Volkoff-like equations for each case, and find some simple
solutions. We conclude that new "simple" black hole solutions of the above
form, supported by a perfect fluid, do not exist.Comment: 24 standard LaTeX pages, no figures. Some change in emphasis; changes
in parametrizations of some of the solutions (ND2, TD2, TD3, NS1); one new
solution (TS4); removal of an incorrect statement (about ND4
Assessment of subjective sleep quality in iron deficiency anaemia
Objectives: We aimed to assess the effect of anemia on subjective sleep quality in patients with iron deficiency anemia (IDA).Methods: One hundred and four patients diagnosed with IDA and 80 healthy individuals, who are gender and age matched, were included in the study. All participants were requested to fill 3 forms: a socio-demographic form (age, gender, marital status, income level and educational status), hospital anxiety and depression (HAD) scale and pittsburgh sleep quality index (PSQI).Results: According to the HAD scale, the average anxiety score was found 9.24±4.37 in patients and 7.58± 4.07 in controls. And, the average depression score was 7.53±4.10 in patients and 6.41±2.74 in controls. The total sleep quality score was 6.71±3.02 in patients and 4.11±1.64 in controls. There was a statistically significant difference in terms of anxiety, depression and sleep quality scores. Linear regression analysis showed no association between anxiety and depression with poor sleeping.Conclusion: IDA affects sleep quality irrespective of psychological symptoms such as depression and anxiety.Keywords: Iron deficiency anemia, sleep quality, anxiet
Overcharging a Black Hole and Cosmic Censorship
We show that, contrary to a widespread belief, one can overcharge a near
extremal Reissner-Nordstrom black hole by throwing in a charged particle, as
long as the backreaction effects may be considered negligible. Furthermore, we
find that we can make the particle's classical radius, mass, and charge, as
well as the relative size of the backreaction terms arbitrarily small, by
adjusting the parameters corresponding to the particle appropriately. This
suggests that the question of cosmic censorship is still not wholly resolved
even in this simple scenario. We contrast this with attempting to overcharge a
black hole with a charged imploding shell, where we find that cosmic censorship
is upheld. We also briefly comment on a number of possible extensions.Comment: 26 pages, 3 figures, LaTe
Concordancia entre la técnica de hemaglutinación indirecta e inmunoabsorción ligado a enzimas en el diagnóstico de toxoplasmosis porcina
El documento digital no refiere un asesorDetermina la concordancia entre las pruebas de HAI y ELISA, para detectar IgG anti-Toxoplasma gondii en el diagnóstico de toxoplasmosis porcina. El trabajo se desarrolla en 407 animales provenientes de crianzas porcinas ubicadas en la franja costera del departamento de Lima. Se colectan las muestras de sangre de cerdos en la fase de acabado, posteriormente las muestras de suero son conservadas en congelación (-70ºC) hasta su procesamiento en el Laboratorio de Parasitología de la Facultad de Medicina Veterinaria de la UNMSM. La concordancia de las técnicas diagnósticas y la seroprevalencia correspondiente se evalúan mediante dos diferentes modelos estadísticos: Indice de Kappa y la prueba de McNemar. En los resultados se halla que la concordancia entre las pruebas de HAI-ELISA a través del índice de Kapa es igual a 26% considerándose de tipo regular, con valores de 18.7 ± 3.8% por el método de HAI, y 14.7 ± 3.4%, por el método de ELISA; sin embargo, mediante la prueba de McNemar no se encuentra diferencias significativas y sugerirían que ambas técnicas son mutuamente reemplazables. Concluyendo que, como la correlación es regular, no se recomienda.Tesi
A radiating dyon solution
We give a non-static exact solution of the Einstein-Maxwell equations (with
null fluid), which is a non-static magnetic charge generalization to the
Bonnor-Vaidya solution and describes the gravitational and electromagnetic
fields of a nonrotating massive radiating dyon. In addition, using the
energy-momentum pseudotensors of Einstein and Landau and Lifshitz we obtain the
energy, momentum, and power output of the radiating dyon and find that both
prescriptions give the same result.Comment: 9 pages, LaTe
Test of the weak cosmic censorship conjecture with a charged scalar field and dyonic Kerr-Newman black holes
A thought experiment considered recently in the literature, in which it is
investigated whether a dyonic Kerr-Newman black hole can be destroyed by
overcharging or overspinning it past extremality by a massive complex scalar
test field, is revisited. Another derivation of the result that this is not
possible, i.e. the weak cosmic censorship is not violated in this thought
experiment, is given. The derivation is based on conservation laws, on a null
energy condition, and on specific properties of the metric and the
electromagnetic field of dyonic Kerr-Newman black holes. The metric is kept
fixed, whereas the dynamics of the electromagnetic field is taken into account.
A detailed knowledge of the solutions of the equations of motion is not needed.
The approximation in which the electromagnetic field is fixed is also
considered, and a derivation for this case is also given. In addition, an older
version of the thought experiment, in which a pointlike test particle is used,
is revisited. The same result, namely the non-violation of the cosmic
censorship, is rederived in a way which is simpler than in earlier works.Comment: 18 pages, LaTe
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