12,083 research outputs found
The silicate absorption profile in the ISM towards the heavily obscured nucleus of NGC 4418
The 9.7-micron silicate absorption profile in the interstellar medium
provides important information on the physical and chemical composition of
interstellar dust grains. Measurements in the Milky Way have shown that the
profile in the diffuse interstellar medium is very similar to the amorphous
silicate profiles found in circumstellar dust shells around late M stars, and
narrower than the silicate profile in denser star-forming regions. Here, we
investigate the silicate absorption profile towards the very heavily obscured
nucleus of NGC 4418, the galaxy with the deepest known silicate absorption
feature, and compare it to the profiles seen in the Milky Way. Comparison
between the 8-13 micron spectrum obtained with TReCS on Gemini and the larger
aperture spectrum obtained from the Spitzer archive indicates that the former
isolates the nuclear emission, while Spitzer detects low surface brightness
circumnuclear diffuse emission in addition. The silicate absorption profile
towards the nucleus is very similar to that in the diffuse ISM in the Milky Way
with no evidence of spectral structure from crystalline silicates or silicon
carbide grains.Comment: 7 Pages, 3 figures. MNRAS in pres
A characterization of dual quermassintegrals and the roots of dual steiner polynomials
For any finite with , we provide a
characterization of those tuples of positive numbers
which are dual querma\ss integrals of two star bodies. It turns out that this
problem is related to the moment problem. Based on this relation we also get
new inequalities for the dual querma\ss integrals. Moreover, the above
characterization will be the key tool in order to investigate structural
properties of the set of roots of dual Steiner polynomials of star bodies
Isospin breaking in the nucleon mass and the sensitivity of β decays to new physics
We discuss the consequences of the approximate conservation of the vector and axial currents for the hadronic matrix elements appearing in β decay if nonstandard interactions are present. In particular, the isovector (pseudo)scalar charge gS(P) of the nucleon can be related to the difference (sum) of the nucleon masses in the absence of electromagnetic effects. Using recent determinations of these quantities from phenomenological and lattice QCD studies we obtain the accurate values gS=1.02(11) and gP=349(9) in the modified minimal subtraction scheme at μ=2 GeV. The consequences for searches of nonstandard scalar interactions in nuclear β decays are studied, finding for the corresponding Wilson coefficient εS=0.0012(24) at 90% C.L., which is significantly more stringent than current LHC bounds and previous low-energy bounds using less precise gS values. We argue that our results could be rapidly improved with updated computations and the direct calculation of certain ratios in lattice QCD. Finally, we discuss the pion-pole enhancement of gP, which makes β decays much more sensitive to nonstandard pseudoscalar interactions than previously thought
Wine tourism in Spain: The case of three wine regions
By far the main focus of contemporary wine tourism research has been in ‘New World’ regions, while it appears to be under development in much of the ‘Old World.’ The present study adds to this underdeveloped body of research in that it addresses a range of wine tourism development issues, across three prominent ‘Old World’ wine regions: La Mancha, La Rioja and Penedès. A total of 94 wineries participated in the study. Respondents’ answers and comments indicate that while many of the participating wineries are several generations, or centuries, old, wine tourism appears to be in its ‘tentative’ stages, that is, only starting to gain momentum. One positive aspect is that most participants (68.1%) indicated that their wineries are open to the public mainly to generate interest for their wine brands among visitors, while 61.7% use the cellar door to educate customers, thus demonstrating wineries’ longer-term strategy to ‘convert’ visitors to brand loyalty through wine tourism. Given the critical role tourism plays for Spain’s economy, with over 50 million visitors per year, these findings can have important implications for the long term sustainability of the wine industry in many of the nation’s wine regions
A Nexafs Study of Nitric Oxide Layers Adsorbed from a nitrite Solution onto a Pt(111) Surface
NO molecules adsorbed on a Pt(111) surface from dipping in an acidic nitrite
solution are studied by near edge X-ray absorption fine structure spectroscopy
(NEXAFS), X-ray photoelectron spectroscopy (XPS), low energy electron
diffraction (LEED) and scanning tunnelling microscopy (STM) techniques. LEED
patterns and STM images show that no long range ordered structures are formed
after NO adsorption on a Pt(111) surface. Although the total NO coverage is
very low, spectroscopic features in N K-edge and O K-edge absorption spectra
have been singled out and related to the different species induced by this
preparation method. From these measurements it is concluded that the NO
molecule is adsorbed trough the N atom in an upright conformation. The maximum
saturation coverage is about 0.3 monolayers, and although nitric oxide is the
major component, nitrite and nitrogen species are slightly co-adsorbed on the
surface. The results obtained from this study are compared with those
previously reported in the literature for NO adsorbed on Pt(111) under UHV
conditions
Sub-arcsec mid-IR observations of NGC 1614: Nuclear star-formation or an intrinsically X-ray weak AGN?
We present new mid-infrared N-band spectroscopy and Q-band photometry of the
local luminous infrared galaxy NGC1614, one of the most extreme nearby
starbursts. We analyze the mid-IR properties of the nucleus (central 150 pc)
and four regions of the bright circumnuclear (diameter~600 pc) star-forming
(SF) ring of this object. The nucleus differs from the circumnuclear SF ring by
having a strong 8-12 micron continuum (low 11.3 micron PAH equivalent width).
These characteristics, together with the nuclear X-ray and sub-mm properties,
can be explained by an X-ray weak active galactic nucleus (AGN), or by peculiar
SF with a short molecular gas depletion time and producing an enhanced
radiation field density. In either case, the nuclear luminosity (L(IR) < 6e43
erg/s) is only <5% of the total bolometric luminosity of NGC1614. So this
possible AGN does not dominate the energy output in this object. We also
compare three star-formation rate (SFR) tracers (Pa, 11.3 micron PAH,
and 24 micron emissions) at 150 pc scales in the circumnuclear ring. In
general, we find that the SFR is underestimated (overestimated) by a factor of
2-4 (2-3) using the 11.3 micron PAH (24 micron) emission with respect to the
extinction corrected Pa SFR. The former can be explained because we do
not include diffuse PAH emission in our measurements, while the latter might
indicate that the dust temperature is particularly warmer in the central
regions of NGC1614.Comment: Accepted for publication in MNRAS; 10 pages, 5 figure
The Top Ten solar analogs in the ELODIE library
Several solar analogs have been identified in the library of high resolution
stellar spectra taken with the echelle spectrograph ELODIE. A purely
differential method has been used, based on the chi2 comparison of a large
number of G dwarf spectra to 8 spectra of the Sun, taken on the Moon and Ceres.
HD 146233 keeps its status of closest ever solar twin (Porto de Mello & da
Silva 1997). Some other spectroscopic analogs have never been studied before,
while the two planet-host stars HD095128 and HD186427 are also part of the
selection. The fundamental parameters found in the literature for these stars
show a surprising dispersion, partly due to the uncertainties which affect
them.
We discuss the advantages and drawbacks of photometric and spectroscopic
methods to search for solar analogs and conclude that they have to be used
jointly to find real solar twins.Comment: 12 pages, accepted in A&
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The Relationship Between Parkinson’s Disease and Essential Tremor: Review of Clinical, Epidemiologic, Genetic, Neuroimaging and Neuropathological Data, and Data on the Presence of Cardinal Signs of Parkinsonism in Essential Tremor
Background: The possible relationship between essential tremor (ET) and Parkinson's disease (PD) has been controversial since the first description of PD. However, there is increasing evidence suggesting an overlap between these two disorders. The aim of this review is to examine the relationship between PD and ET, focusing on clinical, epidemiologic, genetic, neuroimaging, and neuropathological data, and the presence of cardinal parkinsonism symptoms in ET. Methods: We conducted a PubMed search for articles published between 1966 and November 2011 regarding the relationship between ET and PD and the presence of postural tremor in PD patients; the presence of rest tremor, rigidity, and slowed movements in ET patients is reviewed. Results: Clinical series, follow-up studies of ET patients, and case–control and genetic epidemiological studies indicate that ET is associated with increased risk for PD. Some neuroimaging studies and neuropathological reports suggest an association between the two diseases. ET patients show high prevalence of rest tremor, and at least seven studies described slowed movements (possibly related to cerebellar dysfunction and/or bradykinesia) in patients with ET. Discussion: There is reasonable epidemiological and clinical evidence to support a link between ET and PD, although it is not clear what factors predict ET patient risk for developing PD or, more rarely, of PD patients developing ET. Future multicentric and multidisciplinary studies including epidemiological, clinical, neuroimaging, genetic, and neuropathological assessments are required to understand these associations
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