Botulinum toxin type A is a widely used neurotoxin for the treatment of muscle hyperactivity such as dystonia and spasticity. Several clinical trials have also reported an efficacy of subcutaneous or ...intradermal administrations of botulinum toxin A on various neuropathic pain conditions including idiopathic trigeminal neuralgia and found that specific sensory phenotypes were predictors of the response. This narrative review summarizes the potential mechanisms of action, efficacy and safety of botulinum toxin A in neuropathic pain as well as its place in the therapeutic algorithm of neuropathic pain.
•Botulinum toxin A (BTX-A) has therapeutic value in peripheral neuropathic pain or trigeminal neuralgia.•Mechanisms of action are probably central.•Best responders with neuropathic pain seem to be those with evoked and deep pain generally associated with pain paroxysms.•Botulinum toxin type A is recommended as third line for specialist use in peripheral neuropathic pain.
The Galactic warp revealed by Gaia DR2 kinematics Poggio, E; Drimmel, R; Lattanzi, M G ...
Monthly Notices of the Royal Astronomical Society Letters,
11/2018, Letnik:
481, Številka:
1
Journal Article
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ABSTRACT Using Gaia DR2 astrometry, we map the kinematic signature of the Galactic stellar warp out to a distance of 7 kpc from the Sun. Combining Gaia DR2 and 2-Micron All Sky Survey photometry, we ...identify, via a probabilistic approach, $599 \, 494$ upper main sequence (UMS) stars and $12\, 616\, 068$ giants without the need for individual extinction estimates. The spatial distribution of the UMS stars clearly shows segments of the nearest spiral arms. The large-scale kinematics of both the UMS and giant populations show a clear signature of the warp of the Milky Way, apparent as a gradient of 5–6 km s−1 in the vertical velocities from 8 to 14 kpc in Galactic radius. The presence of the signal in both samples, which have different typical ages, suggests that the warp is a gravitationally induced phenomenon.
Taking advantage of the recent
Gaia
Data Release 3 (DR3), we mapped chemical inhomogeneities in the Milky Way’s disc out to a distance of ∼4 kpc from the Sun, using different samples of bright giant ...stars. The samples were selected using effective temperatures and surface gravities from the GSP-Spec module, and they are expected to trace stellar populations of a different typical age. The cool (old) giants exhibit a relatively smooth radial metallicity gradient with an azimuthal dependence. Binning in Galactic azimuth
ϕ
, the slope gradually varies from dM/H/d
R
∼ −0.054 dex kpc
−1
at
ϕ
∼ −20° to ∼ − 0.036 dex kpc
−1
at
ϕ
∼ 20°. On the other hand, the relatively hotter (and younger) stars present remarkable inhomogeneities, which are apparent as three (possibly four) metal-rich elongated features in correspondence with the spiral arms’ locations in the Galactic disc. When projected onto the Galactic radius, those features manifest themselves as statistically significant bumps on top of the observed radial metallicity gradients with amplitudes up to ∼0.05–0.1 dex, making the assumption of a linear radial decrease not applicable for this sample. The strong correlation between the spiral structure of the Galaxy and the observed chemical pattern in the young sample indicates that the spiral arms might be at the origin of the detected chemical inhomogeneities. In this scenario, the spiral arms would leave a strong signature in the younger stars which progressively disappears when cooler (and older) giants are considered.
We identify 51 blue horizontal branch (BHB) stars, 12 possible BHB stars and 58 RR Lyrae stars in Anticentre fields. Their selection does not depend on their kinematics. Light curves and ephemerides ...are given for seven previously unknown RR Lyrae stars. All but four of the RR Lyrae stars are of Oosterhoff type I.
Our selection criteria for BHB stars give results that agree with those used by Smith et al. and Ruhland et al. We use five methods to determine distances for the BHB stars and three methods for the RR Lyrae stars to get distances on a uniform scale. Absolute proper motions largely derived from the Second Guide Star Catalogue (GSCII) and Sloan Digital Sky Survey (Seventh Data Release) data bases are given for these stars; radial velocities are given for 31 of the BHB stars and 37 of the RR Lyrae stars.
Combining these data for BHB and RR Lyrae stars with those previously found in fields at the North Galactic Pole, we find that retrograde orbits dominate for galactocentric distances greater than 12.5 kpc. The majority of metal-poor stars in the solar neighbourhood are known to be concentrated in a L
⊥ versus L
z
angular momentum plot. We show that the ratio of the number of outliers to the number in the main concentration increases with galactocentric distance. The location of these outliers with L
⊥ and L
z
shows that the halo BHB and RR Lyrae stars have more retrograde orbits and a more spherical distribution with increasing galactocentric distance. Six RR Lyrae stars are identified in the H99 group of outliers; the small spread in their Fe/H suggests that they could have come from a single globular cluster. Another group of outliers contains two pairs of RR Lyrae stars; the stars in each pair have similar properties.
ABSTRACT
This work presents the results of a kinematic analysis of the Galaxy that uses a new model as applied to the newest available Gaia data. We carry out the Taylor decomposition of the velocity ...field up to second order for 18 million high luminosity stars (i.e. OBAF-type stars, giants, and subgiants) from the Gaia DR3 data. We determine the components of mean stellar velocities and their first and second partial derivatives (relative to cylindrical coordinates) for more than 28 thousand points in the plane of our Galaxy. We estimate Oort’s constants A, B, C, and K and other kinematics parameters and map them as a function of Galactocentric coordinates. The values found confirm the results of our previous works and are in excellent agreement with those obtained by other authors in the solar neighbourhood. In addition, the introduction of second order partial derivatives of the stellar velocity field allows us to determine the values of the vertical gradient of the Galaxy azimuthal, radial, and vertical velocities. Also, we determine the mean of the Galaxy rotation curve for Galactocentric distances from 4 to 18 kpc by averaging Galactic azimuths in the range −30° < θ < + 30° about the direction Galactic Centre – Sun – Galactic anticentre. Maps of the velocity components and of their partial derivatives with respect to coordinates within 10 kpc of the Sun reveal complex substructures, which provide clear evidence of non-axisymmetric features of the Galaxy. Finally, we show evidence of differences in the Northern and Southern hemispheres stellar velocity fields.
We analyze a new kinematic survey that includes accurate proper motions derived from SDSS DR7 positions, combined with multi-epoch measurements from the GSC-II database. By means of the SDSS ...spectro-photometric data (effective temperature, surface gravity, metallicity, and radial velocities), we estimate photometric parallaxes for a sample of 27 000 FGK (sub)dwarfs with Fe/H < -0.5, which we adopted as tracers of the seven-dimensional space distribution (kinematic phase distribution plus chemical abundance) of the thick disk and inner halo within a few kiloparsecs of the Sun. We find evidence of a kinematics-metallicity correlation, $\partial \langle V_\phi \rangle/ \partial {\rm Fe/H}\approx 40\div 50$ km s-1 dex-1, amongst thick disk stars located between one and three kiloparsecs from the plane and with abundance -1 < Fe/H < -0.5, while no significant correlation is present for Fe/H $\ga$ -0.5. In addition, we estimate a shallow vertical rotation velocity gradient, $\partial \langle V_\phi \rangle/ \partial \left| z\right| = -19 \pm 2$ km s-1 kpc-1, for the thick disk between 1 kpc < |z| < 3 kpc, and a low prograde rotation, 37 ± 3 km s-1 for the inner halo up to 4 kpc. Finally, we briefly discuss the implications of these findings for the thick disk formation scenarios in the context of CDM hierarchical galaxy formation mechanisms and of secular evolutionary processes in galactic disks.
Context.
The
Gaia
-ESO Survey (GES) is a public, high-resolution spectroscopic survey, conducted with the multi-object spectrograph Fibre Large Array Multi Element Spectrograph (FLAMES) on the Very ...Large Telescope (European Southern Observatory, ESO, Cerro Paranal, Chile) from December 2011 to January 2018.
Gaia
-ESO has targeted all the main stellar components of the Milky Way, including thin and thick disc, bulge, and halo. In particular, a large sample of open clusters has been observed, from very young ones, just out of the embedded phase, to very old ones.
Aims.
The different kinds of clusters and stars targeted in them are useful to reach the main science goals of the open cluster part of GES, which are the study of the open cluster structure and dynamics, the use of open clusters to constrain and improve stellar evolution models, and the definition of Galactic disc properties (e.g., metallicity distribution).
Methods.
The
Gaia
-ESO Survey is organised in 19 working groups (WGs), each one being responsible for a task. We describe here the work of three of them, one in charge of the selection of the targets within each cluster or association (WG4), one responsible for defining the most probable candidate member stars (WG1), and another one in charge of the preparation of the observations (WG6). As the entire GES has been conducted before the second
Gaia
data release, we could not make use of the
Gaia
astrometry to define cluster member candidates. We made use of public and private photometry to select the stars to be observed with FLAMES, once brought on a common astrometric system (the one defined by 2MASS). Candidate target selection was based on ground-based proper motions, radial velocities, and X-ray properties when appropriate, for example, and it was mostly used to define the position of the clusters’ evolutionary sequences in the colour-magnitude diagrams. Targets for GIRAFFE were then selected near the sequences in an unbiased way. We used known information on membership, when available, only for the few stars to be observed with UVES.
Results.
We collected spectra for 62 confirmed clusters in the main observing campaign (and a few more clusters were taken from the ESO archive). Among them are very young clusters, where the main targets are pre-main sequence stars, clusters with very hot and massive stars currently on the main sequence, intermediate-age and old clusters where evolved stars are the main targets. Our strategy of making the selection of targets as inclusive and unbiased as possible and of observing a significant and representative fraction of all possible targets permitted us to collect the largest, most accurate, and most homogeneous spectroscopic data set on open star clusters ever achieved.
Aims. The scope of this paper is twofold. First, it describes the simulation scenarios and the results of a large-scale, double-blind test campaign carried out to estimate the potential of Gaia for ...detecting and measuring planetary systems. The identified capabilities are then put in context by highlighting the unique contribution that the Gaia exoplanet discoveries will be able to bring to the science of extrasolar planets in the next decade. Methods. We use detailed simulations of the Gaia observations of synthetic planetary systems and develop and utilize independent software codes in double-blind mode to analyze the data, including statistical tools for planet detection and different algorithms for single and multiple Keplerian orbit fitting that use no a priori knowledge of the true orbital parameters of the systems. Results. 1) Planets with astrometric signatures $\alpha\simeq 3$ times the assumed single-measurement error $\sigma_\psi$ and period $P\leq 5$ yr can be detected reliably and consistently, with a very small number of false positives. 2) At twice the detection limit, uncertainties in orbital parameters and masses are typically $15{-}20\%$. 3) Over 70% of two-planet systems with well-separated periods in the range $0.2\leq P\leq 9$ yr, astrometric signal-to-noise ratio $2\leq\alpha/\sigma_\psi\leq 50$, and eccentricity $e\leq 0.6$ are correctly identified. 4) Favorable orbital configurations (both planets with $P\leq 4$ yr and $\alpha/\sigma_\psi\geq 10$, redundancy over a factor of 2 in the number of observations) have orbital elements measured to better than 10% accuracy >$ 90\%$ of the time, and the value of the mutual inclination angle $i_\mathrm{rel}$ determined with uncertainties $\leq $$10\degr$. 5) Finally, nominal uncertainties obtained from the fitting procedures are a good estimate of the actual errors in the orbit reconstruction. Extrapolating from the present-day statistical properties of the exoplanet sample, the results imply that a Gaia with $\sigma_\psi = 8$ μas, in its unbiased and complete magnitude-limited census of planetary systems, will discover and measure several thousands of giant planets out to 3–4 AUs from stars within 200 pc, and will characterize hundreds of multiple-planet systems, including meaningful coplanarity tests. Finally, we put Gaia's planet discovery potential into context, identifying several areas of planetary-system science (statistical properties and correlations, comparisons with predictions from theoretical models of formation and evolution, interpretation of direct detections) in which Gaia can be expected, on the basis of our results, to have a relevant impact, when combined with data coming from other ongoing and future planet search programs.
Context. The thick disk rotation-metallicity correlation, ∂Vφ/∂Fe/H = 40 ÷ 50 km s-1 dex-1 represents an important signature of the formation processes of the galactic disk. Aims. We use ...nondissipative numerical simulations to follow the evolution of a Milky Way (MW)-like disk to verify if secular dynamical processes can account for this correlation in the old thick disk stellar population. Methods. We followed the evolution of an ancient disk population represented by 10 million particles whose chemical abundances were assigned by assuming a cosmologically plausible radial metallicity gradient with lower metallicity in the inner regions, as expected for the 10-Gyr-old MW. The two cases of a disk with and without a bar were simulated to compare the evolution of their kinematics and radial chemical properties. Results. Migration processes act in both cases and appear to be enhanced in the presence of a central bar. Essentially, inner disk stars move towards the outer regions and populate layers located at higher |z|. In the case of an evolved barred disk, a rotation-metallicity correlation appears, which well resembles the behaviour observed in our Galaxy at a galactocentric distance between 8 kpc and 10 kpc. In particular, we measure a correlation of ∂Vφ/∂ Fe/H ≃ 60 km s-1 dex-1 for particles at 1.5 kpc < |z| < 2.0 kpc that persists up to 6 Gyr. Conclusions. Our pure N-body models can account for the Vφ vs. Fe/H correlation observed in the thick disk of our Galaxy, suggesting that processes internal to the disk such as heating and radial migration play a role in the formation of this old stellar component. In this scenario, the positive rotation-metallicity correlation of the old thick disk population would represent the relic signature of an ancient inverse chemical (radial) gradient in the inner Galaxy, which resulted from accretion of primordial gas.
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