4,580 research outputs found
Using the atmospheric CO2 growth rate to constrain the CO2 flux from land use and land cover change since 1900
We explore the ability of the atmospheric CO2 record since 1900 to constrain the source of CO2 from land use and land cover change (hereafter âland useâ), taking account of uncertainties in other terms in the global carbon budget. We find that the atmospheric constraint favors land use CO2 flux estimates with lower decadal variability and can identify potentially erroneous features, such as emission peaks around 1960 and after 2000, in some published estimates. Furthermore, we resolve an offset in the global carbon budget that is most plausibly attributed to the land use flux. This correction shifts the mean land use flux since 1900 across 20 published estimates down by 0.35 PgC yearâ1 to 1.04 ± 0.57 PgC yearâ1, which is within the range but at the low end of these estimates. We show that the atmospheric CO2 record can provide insights into the time history of the land use flux that may reduce uncertainty in this term and improve current understanding and projections of the global carbon cycle. © 2022 The Authors. Global Change Biology published by John Wiley Sons Ltd
Theta-burst transcranial magnetic stimulation to the prefrontal or parietal cortex does not impair metacognitive visual awareness
Neuroimaging studies commonly associate dorsolateral prefrontal cortex (DLPFC) and pos- terior parietal cortex with conscious perception. However, such studies only investigate cor- relation, rather than causation. In addition, many studies conflate objective performance with subjective awareness. In an influential recent paper, Rounis and colleagues addressed these issues by showing that continuous theta burst transcranial magnetic stimulation (cTBS) applied to the DLPFC impaired metacognitive (subjective) awareness for a percep- tual task, while objective performance was kept constant. We attempted to replicate this finding, with minor modifications, including an active cTBS control site. Using a between- subjects design for both DLPFC and posterior parietal cortices, we found no evidence of a cTBS-induced metacognitive impairment. In a second experiment, we devised a highly rig- orous within-subjects cTBS design for DLPFC, but again failed to find any evidence of meta- cognitive impairment. One crucial difference between our results and the Rounis study is our strict exclusion of data deemed unsuitable for a signal detection theory analysis. Indeed, when we included this unstable data, a significant, though invalid, metacognitive impairment was found. These results cast doubt on previous findings relating metacognitive awareness to DLPFC, and inform the current debate concerning whether or not prefrontal regions are preferentially implicated in conscious perception
Whose expertise is it? Evidence for autistic adults as critical autism experts
This is the final version. Available on open access from Frontiers Media via the DOI in this recordAutistic and non-autistic adults' agreement with scientific knowledge about autism, how they define autism, and their endorsement of stigmatizing conceptions of autism has not previously been examined. Using an online survey, we assessed autism knowledge and stigma among 636 adults with varied relationships to autism, including autistic people and nuclear family members. Autistic participants exhibited more scientifically based knowledge than others. They were more likely to describe autism experientially or as a neutral difference, and more often opposed the medical model. Autistic participants and family members reported lower stigma. Greater endorsement of the importance of normalizing autistic people was associated with heightened stigma. Findings suggest that autistic adults should be considered autism experts and involved as partners in autism research.Professional Staff CongressCity University of New Yor
Response of VIRGO detectors to pre-big-bang gravitons
The sensitivity achievable by a pair of VIRGO detectors to stochastic and
isotropic gravitational wave backgrounds produced in pre-big-bang models is
discussed in view of the development of a second VIRGO interferometer. We
describe a semi-analytical technique allowing to compute the signal-to-noise
ratio for (monotonic or non-monotonic) logarithmic energy spectra of relic
gravitons of arbitrary slope. We apply our results to the case of two
correlated and coaligned VIRGO detectors and we compute their achievable
sensitivities. We perform our calculations both for the usual case of minimal
string cosmological scenario and in the case of a non-minimal scenario where a
long dilaton dominated phase is present prior to the onset of the ordinary
radiation dominated phase. In this framework, we investigate possible
improvements of the achievable sensitivities by selective reduction of the
thermal contributions (pendulum and pendulum's internal modes) to the noise
power spectra of the detectors. Since a reduction of the shot noise does not
increase significantly the expected sensitivity of a VIRGO pair (in spite of
the relative spatial location of the two detectors) our findings support the
experimental efforts directed towards a substantial reduction of thermal noise.Comment: 23 pages in Latex styl
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Fully automated convolutional neural network-based affine algorithm improves liver registration and lesion co-localization on hepatobiliary phase T1-weighted MR images.
BackgroundLiver alignment between series/exams is challenged by dynamic morphology or variability in patient positioning or motion. Image registration can improve image interpretation and lesion co-localization. We assessed the performance of a convolutional neural network algorithm to register cross-sectional liver imaging series and compared its performance to manual image registration.MethodsThree hundred fourteen patients, including internal and external datasets, who underwent gadoxetate disodium-enhanced magnetic resonance imaging for clinical care from 2011 to 2018, were retrospectively selected. Automated registration was applied to all 2,663 within-patient series pairs derived from these datasets. Additionally, 100 within-patient series pairs from the internal dataset were independently manually registered by expert readers. Liver overlap, image correlation, and intra-observation distances for manual versus automated registrations were compared using paired t tests. Influence of patient demographics, imaging characteristics, and liver uptake function was evaluated using univariate and multivariate mixed models.ResultsCompared to the manual, automated registration produced significantly lower intra-observation distance (p < 0.001) and higher liver overlap and image correlation (p < 0.001). Intra-exam automated registration achieved 0.88 mean liver overlap and 0.44 mean image correlation for the internal dataset and 0.91 and 0.41, respectively, for the external dataset. For inter-exam registration, mean overlap was 0.81 and image correlation 0.41. Older age, female sex, greater inter-series time interval, differing uptake, and greater voxel size differences independently reduced automated registration performance (p †0.020).ConclusionA fully automated algorithm accurately registered the liver within and between examinations, yielding better liver and focal observation co-localization compared to manual registration
Insecurity for compact surfaces of positive genus
A pair of points in a riemannian manifold is secure if the geodesics
between the points can be blocked by a finite number of point obstacles;
otherwise the pair of points is insecure. A manifold is secure if all pairs of
points in are secure. A manifold is insecure if there exists an insecure
point pair, and totally insecure if all point pairs are insecure.
Compact, flat manifolds are secure. A standing conjecture says that these are
the only secure, compact riemannian manifolds. We prove this for surfaces of
genus greater than zero. We also prove that a closed surface of genus greater
than one with any riemannian metric and a closed surface of genus one with
generic metric are totally insecure.Comment: 37 pages, 11 figure
Fall-back crust around a quark-nova compact remnant I: The degenerate shell case with applications to SGRs, AXPs and XDINs
We explore the formation and evolution of debris ejected around quark stars
in the Quark Nova scenario, and the application to Soft Gamma-ray Repeaters
(SGRs) and Anomolous X-ray Pulsars (AXPs). If an isolated neutron star explodes
as a Quark Nova, an Iron-rich shell of degenerate matter forms out of the
fall-back (crust) material. Our model can account for many of the observed
features of SGRs and AXPs such as: (i) the two types of bursts (giant and
regular); (ii) the spin-up and spin-down episodes during and following the
bursts with associated persistant increases in ; (iii) the energetics
of the boxing day burst, SGR180620; (iv) the presence of an Iron line as
observed in SGR190014; (v) the correlation between the far-Infrared and the
X-ray fluxes during the bursting episode and the quiescent phase; (vi) the hard
X-ray component observed in SGRs during the giant bursts, and (vii) the
discrepancy between the ages of SGRs/AXPs and their supernova remnants. We also
find a natural evolutionary relationship between SGRs and AXPs in our model
which predicts that only the youngest SGRs/AXPs are most likely to exhibit
strong bursting. Many features of X-ray Dim Isolated Neutron stars (XDINs) are
also accounted for in our model such as, (i) the two-component blackbody
spectra; (ii) the absorption lines around 300 eV; and (iii) the excess optical
emission.Comment: submitted to Ap
Sensitivity of a VIRGO pair to stochastic GW backgrounds
The sensitivity of a pair of VIRGO interferometers to gravitational waves
backgrounds (GW) of cosmological origin is analyzed for the cases of maximal
and minimal overlap of the two detectors. The improvements in the detectability
prospects of scale-invariant and non-scale-invariant logarithmic energy spectra
of relic GW are discussed.Comment: 25 pages in RevTex style with 6 figure
Ergodic Jacobi matrices and conformal maps
We study structural properties of the Lyapunov exponent and the
density of states for ergodic (or just invariant) Jacobi matrices in a
general framework. In this analysis, a central role is played by the function
as a conformal map between certain domains. This idea goes
back to Marchenko and Ostrovskii, who used this device in their analysis of the
periodic problem
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