455 research outputs found
Tourette syndrome as a motor disorder revisited – Evidence from action coding
Because tics are the defining clinical feature of Tourette syndrome, it is conceptualized predominantly as a motor disorder. There is some evidence though suggesting that the neural basis of Tourette syndrome is related to perception–action processing and binding between perception and action. However, binding processes have not been examined in the motor domain in these patients. If it is particularly perception–action binding but not binding processes within the motor system, this would further corroborate that Tourette syndrome it is not predominantly, or solely, a motor disorder. Here, we studied N = 22 Tourette patients and N = 24 healthy controls using an established action coding paradigm derived from the Theory of Event Coding framework and concomitant EEG-recording addressing binding between a planned but postponed, and an interleaved immediate reaction with different levels of overlap of action elements. Behavioral performance during interleaved action coding was normal in Tourette syndrome. Response locked lateralized readiness potentials reflecting processes related to motor execution were larger in Tourette syndrome, but only in simple conditions. However, pre-motor processes including response preparation and configuration reflected by stimulus-locked lateralized readiness potentials were normal. This was supported by a Bayesian data analysis providing evidence for the null hypothesis. The finding that processes integrating different action-related elements prior to motor execution are normal in Tourette syndrome suggests that Tourette it is not solely a motor disorder. Considering other recent evidence, the data show that changes in “binding” in Tourette syndrome are specific for perception–action integration but not for action coding
The Lick AGN Monitoring Project: Reverberation Mapping of Optical Hydrogen and Helium Recombination Lines
We have recently completed a 64-night spectroscopic monitoring campaign at
the Lick Observatory 3-m Shane telescope with the aim of measuring the masses
of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected
masses in the range ~10^6-10^7M_sun and also the well-studied nearby active
galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including
NGC 5548) showed optical variability of sufficient strength during the
monitoring campaign to allow for a time lag to be measured between the
continuum fluctuations and the response to these fluctuations in the broad
Hbeta emission, which we have previously reported. We present here the light
curves for the Halpha, Hgamma, HeII 4686, and HeI 5876 emission lines and the
time lags for the emission-line responses relative to changes in the continuum
flux. Combining each emission-line time lag with the measured width of the line
in the variable part of the spectrum, we determine a virial mass of the central
supermassive black hole from several independent emission lines. We find that
the masses are generally consistent within the uncertainties. The time-lag
response as a function of velocity across the Balmer line profiles is examined
for six of the AGNs. Finally we compare several trends seen in the dataset
against the predictions from photoionization calculations as presented by
Korista & Goad. We confirm several of their predictions, including an increase
in responsivity and a decrease in the mean time lag as the excitation and
ionization level for the species increases. Further confirmation of
photoionization predictions for broad-line gas behavior will require additional
monitoring programs for these AGNs while they are in different luminosity
states. [abridged]Comment: 37 pages, 18 figures and 15 tables, accepted for publication in the
Astrophysical Journa
Measuring pH variability using an experimental sensor on an underwater glider
Autonomous underwater gliders offer the capability of measuring oceanic parameters continuously at high resolution in both vertical and horizontal planes, with timescales that can extend to many months. An experimental ion sensitive field effect transistor (ISFET) sensor measuring pH on the total scale was attached to a glider during the REP14 – MED experiment in June 2014 in the northwestern Mediterranean Sea. During the deployment, pH was sampled at depths of up to 1000 m, along an 80 km transect over a period of 12 days. Water samples were collected from a nearby ship and analysed for dissolved inorganic carbon concentration and total alkalinity to derive pH for validating the ISFET measurements. The vertical resolution of the pH sensor was good (1 to 2 m), but stability was poor, and the sensor drifted in a non-monotonous fashion. In order to remove the sensor drift, a time-dependent, depth-invariant offset was applied throughout the water column for each dive, reducing the spread of the data by approximately two thirds. Furthermore, the ISFET sensor required temperature and pressure-based corrections, which were achieved using linear regression. Correcting for this decreased the apparent sensor pH variability by a further 13 to 31 %. Sunlight caused an apparent sensor pH decrease of up to 0.1 in surface waters around local noon, highlighting the importance of shielding the sensor away from light in future deployments. The corrected pH from the ISFET sensor is presented along with potential temperature, salinity, potential density anomalies (σθ), and dissolved oxygen concentrations (c(O2)) measured by the glider, providing insights into physical and biogeochemical variability in this region. pH maxima were identified at the depth of the summer chlorophyll maximum, where high c(O2) values were also found. Longitudinal pH variations at depth (σθ > 28.8 kg m−3) highlighted variability of water masses in this region. Higher pH was observed where salinity was > 38.65, and lower pH was found where salinity ranged between 38.3 and 38.65. It seemed that the higher pH was associated with saltier Levantine Intermediate Water. Furthermore, shoaling isopycnals closer to shore coinciding with low pH, high salinity, low c(O2) waters may be indicative of upwelling
Reverberation Mapping Measurements of Black Hole Masses in Six Local Seyfert Galaxies
We present the final results from a high sampling rate, multi-month,
spectrophotometric reverberation mapping campaign undertaken to obtain either
new or improved Hbeta reverberation lag measurements for several relatively
low-luminosity AGNs. We have reliably measured thetime delay between variations
in the continuum and Hbeta emission line in six local Seyfert 1 galaxies. These
measurements are used to calculate the mass of the supermassive black hole at
the center of each of these AGNs. We place our results in context to the most
current calibration of the broad-line region (BLR) R-L relationship, where our
results remove outliers and reduce the scatter at the low-luminosity end of
this relationship. We also present velocity-resolved Hbeta time delay
measurements for our complete sample, though the clearest velocity-resolved
kinematic signatures have already been published.Comment: 52 pages (AASTeX: 29 pages of text, 8 tables, 7 figures), accepted
for publication in the Astrophysical Journa
The Black Hole Mass of NGC 4151: Comparison of Reverberation Mapping and Stellar Dynamical Measurements
We present a stellar dynamical estimate of the black hole (BH) mass in the
Seyfert 1 galaxy, NGC 4151. We analyze ground-based spectroscopy as well as
imaging data from the ground and space, and we construct 3-integral
axisymmetric models in order to constrain the BH mass and mass-to-light ratio.
The dynamical models depend on the assumed inclination of the kinematic
symmetry axis of the stellar bulge. In the case where the bulge is assumed to
be viewed edge-on, the kinematical data give only an upper limit to the mass of
the BH of ~4e7 M_sun (1 sigma). If the bulge kinematic axis is assumed to have
the same inclination as the symmetry axis of the large-scale galaxy disk (i.e.,
23 degrees relative to the line of sight), a best-fit dynamical mass between
4-5e7 M_sun is obtained. However, because of the poor quality of the fit when
the bulge is assumed to be inclined (as determined by the noisiness of the
chi^2 surface and its minimum value), and because we lack spectroscopic data
that clearly resolves the BH sphere of influence, we consider our measurements
to be tentative estimates of the dynamical BH mass. With this preliminary
result, NGC 4151 is now among the small sample of galaxies in which the BH mass
has been constrained from two independent techniques, and the mass values we
find for both bulge inclinations are in reasonable agreement with the recent
estimate from reverberation mapping (4.57[+0.57/-0.47]e7 M_sun) published by
Bentz et al.Comment: 20 pages, including 11 low-res figures. Accepted for publication in
ApJ. High resolution version available upon reques
The Lick AGN Monitoring Project: Recalibrating Single-Epoch Virial Black Hole Mass Estimates
We investigate the calibration and uncertainties of black hole mass estimates
based on the single-epoch (SE) method, using homogeneous and high-quality
multi-epoch spectra obtained by the Lick Active Galactic Nucleus (AGN)
Monitoring Project for 9 local Seyfert 1 galaxies with black hole masses < 10^8
M_sun. By decomposing the spectra into their AGN and stellar components, we
study the variability of the single-epoch Hbeta line width (full width at
half-maximum intensity, FWHM_Hbeta; or dispersion, sigma_Hbeta) and of the AGN
continuum luminosity at 5100A (L_5100). From the distribution of the "virial
products" (~ FWHM_Hbeta^2 L_5100^0.5 or sigma_Hbeta^2 L_5100^0.5) measured from
SE spectra, we estimate the uncertainty due to the combined variability as ~
0.05 dex (12%). This is subdominant with respect to the total uncertainty in SE
mass estimates, which is dominated by uncertainties in the size-luminosity
relation and virial coefficient, and is estimated to be ~ 0.46 dex (factor of ~
3). By comparing the Hbeta line profile of the SE, mean, and root-mean-square
(rms) spectra, we find that the Hbeta line is broader in the mean (and SE)
spectra than in the rms spectra by ~ 0.1 dex (25%) for our sample with
FWHM_Hbeta < 3000 km/s. This result is at variance with larger mass black holes
where the difference is typically found to be much less than 0.1 dex. To
correct for this systematic difference of the Hbeta line profile, we introduce
a line-width dependent virial factor, resulting in a recalibration of SE black
hole mass estimators for low-mass AGNs.Comment: Accepted for publication in ApJ. 18 pages, 17 figure
NGC 5548 in a Low-Luminosity State: Implications for the Broad-Line Region
We describe results from a new ground-based monitoring campaign on NGC 5548,
the best studied reverberation-mapped AGN. We find that it was in the lowest
luminosity state yet recorded during a monitoring program, namely L(5100) = 4.7
x 10^42 ergs s^-1. We determine a rest-frame time lag between flux variations
in the continuum and the Hbeta line of 6.3 (+2.6/-2.3) days. Combining our
measurements with those of previous campaigns, we determine a weighted black
hole mass of M_BH = 6.54 (+0.26/-0.25) x 10^7 M_sun based on all broad emission
lines with suitable variability data. We confirm the previously-discovered
virial relationship between the time lag of emission lines relative to the
continuum and the width of the emission lines in NGC 5548, which is the
expected signature of a gravity-dominated broad-line region. Using this lowest
luminosity state, we extend the range of the relationship between the
luminosity and the time lag in NGC 5548 and measure a slope that is consistent
with alpha = 0.5, the naive expectation for the broad line region for an
assumed form of r ~ L^alpha. This value is also consistent with the slope
recently determined by Bentz et al. for the population of reverberation-mapped
AGNs as a whole.Comment: 24 pages, 3 tables, 7 figures, accepted for publication in Ap
Oncogenic GNAQ mutations are not correlated with disease-free survival in uveal melanoma
BackgroundRecently, oncogenic G protein alpha subunit q (GNAQ) mutations have been described in about 50% of uveal melanomas and in the blue nevi of the skin.MethodsGNAQ exon 5 was amplified from 75 ciliary body and choroidal melanoma DNAs and sequenced directly. GNAQ mutation status was correlated with disease-free survival (DFS), as well as other clinical and histopathological factors, and with chromosomal variations detected by FISH and CGH.ResultsOf the 75 tumour DNA samples analysed, 40 (53.3%) harboured oncogenic mutations in GNAQ codon 209. Univariate and multivariate analysis showed that GNAQ mutation status was not significantly correlated with DFS.ConclusionThe GNAQ mutation status is not suitable to predict DFS. However, the high frequency of GNAQ mutations may render it a promising target for therapeutic intervention
Measuring the mass of the central black hole in the bulgeless galaxy ngc 4395 from gas dynamical modeling
NGC 4395 is a bulgeless spiral galaxy, harboring one of the nearest known type 1 Seyfert nuclei. Although there is no consensus on the mass of its central engine, several estimates suggest it is one of the lightest massive black holes (MBHs) known. We present the first direct dynamical measurement of the mass of this MBH from a combination of two-dimensional gas kinematic data, obtained with the adaptive optics assisted near-infrared integral field spectrograph Gemini/NIFS and high-resolution multiband photometric data from Hubble Space Telescope's Wide Field Camera 3. We use the photometric data to model the shape and stellar mass-to-light ratio of the nuclear star cluster (NSC). From the Gemini/NIFS observations, we derive the kinematics of warm molecular hydrogen gas as traced by emission through the H2 1–0 S(1) transition. These kinematics show a clear rotational signal, with a position angle orthogonal to NGC 4395's radio jet. Our best-fitting tilted ring models of the kinematics of the molecular hydrogen gas contain a black hole with mass M={4}-3+8× {10}5 M⊙ (3σ uncertainties) embedded in an NSC of mass M=2× {10}6 M⊙. Our black hole mass measurement is in excellent agreement with the reverberation mapping mass estimate of Peterson et al. but shows some tension with other mass measurement methods based on accretion signals
- …