11,885 research outputs found
Magnetic fields generated by r-modes in accreting millisecond pulsars
In millisecond pulsars the existence of the Coriolis force allows the
development of the so-called Rossby oscillations (r-modes) which are know to be
unstable to emission of gravitational waves. These instabilities are mainly
damped by the viscosity of the star or by the existence of a strong magnetic
field. A fraction of the observed millisecond pulsars are known to be inside
Low Mass X-ray Binaries (LMXBs), systems in which a neutron star (or a black
hole) is accreting from a donor whose mass is smaller than 1 . Here we
show that the r-mode instabilities can generate strong toroidal magnetic fields
by inducing differential rotation. In this way we also provide an alternative
scenario for the origin of the magnetars.Comment: 6 pages, 3 figures, Proceedings conference "Theoretical Nuclear
Physics", Cortona October 200
Follow-up study of over three years of patients with uveitis after cataract phacoemulsification: outcomes and complications
Purpose: To evaluate the rate and onset of intraoperative and postoperative complications post-phacoemulsification.
Methods: One hundred sixty-two eyes of 145 patients with uveitis who underwent phacoemulsification
between 2006 and 2009 were identified through surgical record review. Fifty-nine eyes of 46 patients met
the inclusion criteria. Hazard ratio (HR) and Kaplan-Meier survival probability were calculated for each class
of uveitis. Results: Macular edema (ME) resulted to be associated to chronic postoperative inflammation
(r = 0.6; p = 0.00) and mostly related to patients who presented more than one postoperative relapse/year (r = 0.2;
p = 0.02). Fuchs uveitis resulted to be a risk factor for posterior capsule opacification (PCO) (HR 3.36
IC95%1.0-10.5; p = 0.03). Hypotony and elevated intraocular pressure (IOP) were detected in the anterior uveitis
group (0.02 EY). Conclusion: The HR to develop ME was significantly related to chronic anterior uveitis. PCO
and elevated IOP are
Nonlinear response and fluctuation dissipation relations
A unified derivation of the off equilibrium fluctuation dissipation relations
(FDR) is given for Ising and continous spins to arbitrary order, within the
framework of Markovian stochastic dynamics. Knowledge of the FDR allows to
develop zero field algorithms for the efficient numerical computation of the
response functions. Two applications are presented. In the first one, the
problem of probing for the existence of a growing cooperative length scale is
considered in those cases, like in glassy systems, where the linear FDR is of
no use. The effectiveness of an appropriate second order FDR is illustrated in
the test case of the Edwards-Anderson spin glass in one and two dimensions. In
the second one, the important problem of the definition of an off equilibrium
effective temperature through the nonlinear FDR is considered. It is shown
that, in the case of coarsening systems, the effective temperature derived from
the second order FDR is consistent with the one obtained from the linear FDR.Comment: 24 pages, 6 figure
The insidious boosting of thermally pulsing asymptotic giant branch stars in intermediate-age magellanic cloud clusters
In the recent controversy about the role of thermally pulsing asymptotic giant branch (TP-AGB) stars in evolutionary population synthesis (EPS) models of galaxies, one particular aspect is puzzling: TP-AGB models aimed at reproducing the lifetimes and integrated fluxes of the TP-AGB phase in Magellanic Cloud (MC) clusters, when incorporated into EPS models, are found to overestimate, to various extents, the TP-AGB contribution in resolved star counts and integrated spectra of galaxies. In this paper, we call attention to a particular evolutionary aspect, linked to the physics of stellar interiors, that in all probability is the main cause of this conundrum. As soon as stellar populations intercept the ages at which red giant branch stars first appear, a sudden and abrupt change in the lifetime of the core He-burning phase causes a temporary "boost" in the production rate of subsequent evolutionary phases, including the TP-AGB. For a timespan of about 0.1 Gyr, triple TP-AGB branches develop at slightly different initial masses, causing their frequency and contribution to the integrated luminosity of the stellar population to increase by a factor of similar to 2. The boost occurs for turn-off masses of similar to 1.75 M-circle dot , just in the proximity of the expected peak in the TP-AGB lifetimes (for MC metallicities), and for ages of similar to 1.6 Gyr. Coincidently, this relatively narrow age interval happens to contain the few very massive MC clusters that host most of the TP-AGB stars used to constrain stellar evolution and EPS models. This concomitance makes the AGB-boosting particularly insidious in the context of present EPS models. As we discuss in this paper, the identification of this evolutionary effect brings about three main consequences. First, we claim that present estimates of the TP-AGB contribution to the integrated light of galaxies derived from MC clusters are biased toward too large values. Second, the relative TP-AGB contribution of single-burst populations falling in this critical age range cannot be accurately derived by approximations such as the fuel consumption theorem, which ignore, by construction, the above evolutionary effect. Third, a careful revision of AGB star populations in intermediate-age MC clusters is urgently demanded, promisingly with the aid of detailed sets of stellar isochrones
(Down-to-)Earth matter effect in supernova neutrinos
Neutrino oscillations in the Earth matter may introduce peculiar modulations
in the supernova (SN) neutrino spectra. The detection of this effect has been
proposed as diagnostic tool for the neutrino mass hierarchy at "large" 1-3
leptonic mixing angle theta13. We perform an updated study on the observability
of this effect at large next-generation underground detectors (i.e., 0.4 Mton
water Cherenkov, 50 kton scintillation and 100 kton liquid Argon detectors)
based on neutrino fluxes from state-of-the-art SN simulations and accounting
for statistical fluctuations via Montecarlo simulations. Since the average
energies predicted by recent simulations are lower than previously expected and
a tendency towards the equalization of the neutrino fluxes appears during the
SN cooling phase, the detection of the Earth matter effect will be more
challenging than expected from previous studies. We find that none of the
proposed detectors shall be able to detect the Earth modulation for the
neutrino signal of a typical galactic SN at 10 kpc. It should be observable in
a 100 kton liquid Argon detector for a SN at few kpc and all three detectors
would clearly see the Earth signature for very close-by stars only (d ~ 0.2
kpc). Finally, we show that adopting IceCube as co-detector together with a
Mton water Cherenkov detector is not a viable option either.Comment: (14 pages, 5 ps figures
Oral Examination
The oral cavity is the first component of the digestive tract, which is delimited by the lips anteriorly and the oropharynx posteriorly. The oral cavity functions as a protective barrier and is an essential component for speech and swallowing, mastication, digestion, and taste sensation.
The oral examination comprises a uniform and consistent inspection of the head and neck and an intraoral evaluation of the hard and soft tissues (see the images below) in conjunction with a thorough medical and dental history. The entire mouth should be inspected regardless of the patient’s chief complaint and reasons for the visit. [1, 2] Good patient’s history and careful examination are important to establish the correct diagnosis and provide appropriate treatment.
The physical examination begins with an extraoral examination to identify possible lesions (such as rash, erythema, and pigmentation), swelling or facial asymmetry. The head and neck should be palpated to identify any tenderness, masses and lymphadenopathy. All muscles of mastication and temporomandibular joint should be palpated for tenderness; patients should be asked to open and close the mouth multiple times to evaluate any limited opening, deviations or asymmetries. The cranial nerve examination should be performed to assess possible neurosensory and neuromuscular deficits.
A good light source is fundamental for a good intraoral examination. Any intraoral lesion should be described with respect to size, extent, thickness, color, texture, consistency, and tenderness
Reentrant behavior of the phase stiffness in Josephson junction arrays
The phase diagram of a 2D Josephson junction array with large substrate
resistance, described by a quantum XY model, is studied by means of Fourier
path-integral Monte Carlo. A genuine Berezinskii-Kosterlitz-Thouless transition
is found up to a threshold value g* of the quantum coupling, beyond which no
phase coherence is established. Slightly below g* the phase stiffness shows a
reentrant behavior with temperature, in connection with a low-temperature
disappearance of the superconducting phase, driven by strong nonlinear quantum
fluctuations.Comment: 4 pages, 7 figures, to appear in Phys.Rev.Let
Checkerboards, stripes and corner energies in spin models with competing interactions
We study the zero temperature phase diagram of Ising spin systems in two
dimensions in the presence of competing interactions, long range
antiferromagnetic and nearest neighbor ferromagnetic of strength J. We first
introduce the notion of a "corner energy" which shows, when the
antiferromagnetic interaction decays faster than the fourth power of the
distance, that a striped state is favored with respect to a checkerboard state
when J is close to J_c, the transition to the ferromagnetic state, i.e., when
the length scales of the uniformly magnetized domains become large. Next, we
perform detailed analytic computations on the energies of the striped and
checkerboard states in the cases of antiferromagnetic interactions with
exponential decay and with power law decay r^{-p}, p>2, that depend on the
Manhattan distance instead of the Euclidean distance. We prove that the striped
phase is always favored compared to the checkerboard phase when the scale of
the ground state structure is very large. This happens for J\lesssim J_c if
p>3, and for J sufficiently large if 2<p<=3. Many of our considerations
involving rigorous bounds carry over to dimensions greater than two and to more
general short-range ferromagnetic interactions.Comment: 21 pages, 3 figure
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