796 research outputs found
Two regularizations - two different models of Nambu-Jona-Lasinio
Two variants of the Nambu--Jona-Lasinio model -- the model with 4-dimensional
cutoff and the model with dimensionally-analytical regularization -- are
systematically compared. It is shown that they are, in essence, two different
models of light-quark interaction. In the mean-field approximation the
distinction becomes apparent in a behavior of scalar amplitude near the
threshold. For 4-dimensional cutoff the pole term can be extracted, which
corresponds to sigma-meson. For dimensionally-analytical regularization the
singularity of the scalar amplitude is not pole, and this singularity is quite
disappeared at some value of the regularization parameter.
Still more essential distinction of these models exists in the
next-to-leading order of mean-field expansion. The calculations of meson
contributions in the quark chiral condensate and in the dynamical quark mass
demonstrate, that these contributions though their relatively smallness can
destabilize the Nambu--Jona-Lasinio model with 4-dimensional cutoff. On the
contrary, the Nambu--Jona-Lasinio model with dimensionally-analytical
regularization is stabilized with the next-to-leading order, i.e. the value of
the regularization parameter shifts to the stability region, where these
contributions decrease.Comment: 14 pages; Journal version; parameter fixing procedure is modifie
Opportunistic screening for hypertension in the general population in Bulgaria: international society of hypertension may measurement month campaign
Cardiovascular diseases are not only the leading causes of mortality in Bulgaria but also the mortality rate is twice as high as the European Union average, so screening programmes identifying subjects with elevated blood pressure (BP) are of utmost importance. May Measurement Month (MMM) is an annual global initiative of the International Society of hypertension that began in 2017 aimed at raising awareness of high BP. Bulgaria joined the 3rd campaign of MMM in 2019 and an overview of the results of Bulgarian participation are presented in this paper. Hypertension was defined as systolic BP â„ 140 mm Hg and diastolic BP â„ 90 mm Hg or treatment for hypertension, statistical analysis followed the standard MMM protocol. In Bulgaria, 150 screening points were set up in primary and secondary care facilities, in pharmacies, and outdoor spaces across 21 administrative districts. Out of 3678 individuals screened, 2587 participants (70.3%) had hypertension. Of 2896 participants with hypertension, 35.6% had controlled BP. Out of 1760 participants not on antihypertensive medication, 669 (38%) had elevated BP. In the case of treated individuals (n = 1918), 997 (52%) had uncontrolled hypertension. In the untreated cohort, every 4th subject had elevated BP, whilst among patients on antihypertensive medication, every second had uncontrolled BP, the worst results in terms of diagnosis and treatment are observed in men. By identifying almost two-third of the whole screened cohort with the possibility of newly diagnosed or uncontrolled hypertension, our results confirm the importance of BP screening campaigns
Transient and asymmetric dust structures in the TeV-bright nova RS Oph revealed by spectropolarimetry
A long-standing question related to nova eruptions is how these eruptions can
lead to the formation of dust despite the ostensibly inhospitable environment
for dust within the hot, irradiated ejecta. Novae in systems such as the
symbiotic binary RS Oph offers a articularly clear view of some nova shocks and
any associated dust production. Here we use spectropolarimetric monitoring of
the RS Oph starting two days after its eruption in 2021 Aug. to show that: dust
was present in the RS Oph system as early as two days into the 2021 eruption;
the spatial distribution of this early dust was asymmetric, with components
both aligned with and perpendicular to the orbital plane of the binary; between
two and nine days after the start of the eruption, this early dust was
gradually destroyed; and dust was again created, aligned roughly with the
orbital plane of the binary, more than 80 days after the start of the outburst,
most likely as a result of shocks that arose as the ejecta interacted with
circumbinary material concentrated in the orbital plane. Modelling of X-rays
and very-high energy GeV and TeV emission from RS Oph days to months into the
2021 eruption suggests that collisions between the ejecta and the circumbinary
material may have led to shock formation in two regions: the polar -
perpendicular to the orbital plane where collimated outflows have been observed
after prior eruptions, and a circumbinary torus in the orbital plane. The
observations described here indicate that dust formed in approximately the same
two regions, supporting the connection between shocks and dust in novae and
revealing a very early onset of asymmetry. The spectropolarimetric signatures
of RS Oph in the first week into the 2021 outburst indicate: polarized flux
across the H{\alpha} emission line and position angle orientation relative to
the radio axis are similar to the spectropolarimetric signatures of AGNs.Comment: 9 pages, 10 figures, 1 table, resubmitted to the Astronomy &
Astrophysics after the first reviewer's repor
Radial velocity eclipse mapping of exoplanets
Planetary rotation rates and obliquities provide information regarding the
history of planet formation, but have not yet been measured for evolved
extrasolar planets. Here we investigate the theoretical and observational
perspective of the Rossiter-McLauglin effect during secondary eclipse (RMse)
ingress and egress for transiting exoplanets. Near secondary eclipse, when the
planet passes behind the parent star, the star sequentially obscures light from
the approaching and receding parts of the rotating planetary surface. The
temporal block of light emerging from the approaching (blue-shifted) or
receding (red-shifted) parts of the planet causes a temporal distortion in the
planet's spectral line profiles resulting in an anomaly in the planet's radial
velocity curve. We demonstrate that the shape and the ratio of the
ingress-to-egress radial velocity amplitudes depends on the planetary
rotational rate, axial tilt and impact factor (i.e. sky-projected planet
spin-orbital alignment). In addition, line asymmetries originating from
different layers in the atmosphere of the planet could provide information
regarding zonal atmospheric winds and constraints on the hot spot shape for
giant irradiated exoplanets. The effect is expected to be most-pronounced at
near-infrared wavelengths, where the planet-to-star contrasts are large. We
create synthetic near-infrared, high-dispersion spectroscopic data and
demonstrate how the sky-projected spin axis orientation and equatorial velocity
of the planet can be estimated. We conclude that the RMse effect could be a
powerful method to measure exoplanet spins.Comment: 7 pages, 3 figures, 1 table, accepted for publication in ApJ on 2015
June 1
Remineralization of demineralized dentin using a dual analog system.
ObjectiveImproved methods are needed to remineralize dentin caries in order to promote conservation of dentin tissue and minimize the surgical interventions that are currently required for clinical treatment. Here, we test the hypothesis that bulk substrates can be effectively mineralized via a dual analog system proposed by others, using a tripolyphosphate (TPP) "templating analog" and a poly(acrylic acid) (PAA) or poly(aspartic acid) (pAsp) "sequestration analog," the latter of which generates the polymer-induced liquid-precursor (PILP) mineralization process studied in our laboratory.Material & methodsDemineralized human dentin slices were remineralized with and without pre-treatment with TPP, using either PAA or pAsp as the PILP process-directing agent. A control experiment with no polymer present was used for comparison.ResultsNo mineralization was observed in any of the PAA groups. In both the pAsp and no polymer groups, TPP inhibited mineralization on the surfaces of the specimens but promoted mineralization within the interiors. Pre-treatment with TPP enhanced overall mineralization of the pAsp group. However, when analysed via TEM, regions with little mineral were still present.ConclusionPoly(acrylic acid) was unable to remineralize demineralized dentin slices under the conditions employed, even when pre-treated with TPP. However, pre-treatment with TPP enhanced overall mineralization of specimens that were PILP-remineralized using pAsp
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