The second survey of the molecular clouds in the Large Magellanic Cloud in super(12)CO was carried out by NANTEN. The sensitivity of this survey is twice as high as that of the previous NANTEN ...survey, leading to a detection of molecular clouds with image M sub(image). We identified 272 molecular clouds, 230 of which are detected at three or more observed positions. We derived the physical properties, such as size, line width, and virial mass, of the 164 GMCs that have an extent more than the beam size of NANTEN in both the major and minor axes. The CO luminosity and virial mass of the clouds show a good correlation of image, with a Spearman rank correlation of 0.8, suggesting that the clouds are in nearly virial equilibrium. Assuming the clouds are in virial equilibrium, we derived an X sub(CO)-factor of image cm super(-2) (K km s super(-1)) super(-1). The mass spectrum of the clouds is fitted well by a power law of image above the completeness limit of image M sub(image). The slope of the mass spectrum becomes steeper if we fit only the massive clouds, e.g., image for image M sub(image).
ABSTRACT
Recent observations of Sgr A* by the GRAVITY instrument have astrometrically tracked infrared (IR) flares at distances of ∼10 gravitational radii (rg). In this paper, we study a model for ...the flares based on 3D general relativistic magnetohydrodynamic (GRMHD) simulations of magnetically arrested accretion discs (MADs) that exhibit violent episodes of flux escape from the black hole magnetosphere. These events are attractive for flare modelling for several reasons: (i) the magnetically dominant regions can resist being disrupted via magnetorotational turbulence and shear; (ii) the orientation of the magnetic field is predominantly vertical as suggested by the GRAVITY data; and (iii) the magnetic reconnection associated with the flux eruptions could yield a self-consistent means of particle heating/acceleration during the flare events. In this analysis, we track erupted flux bundles and provide distributions of sizes, energies, and plasma parameter. In our simulations, the orbits tend to circularize at a range of radii from ${\sim} 5\hbox{ to }40\, r_{\rm g}$. The magnetic energy contained within the flux bundles ranges up to ${\sim} 10^{40}\,\rm erg$, enough to power IR and X-ray flares. We find that the motion within the magnetically supported flow is substantially sub-Keplerian, in tension with the inferred period–radius relation of the three GRAVITY flares.
The present work demonstrates that vertically aligned graphene (VG)/diamond heterojunctions can function as optoelectronically-controllable synapses, which are connection parts of neurons and key ...elements for the memory functions of human brain. These junctions mimic several of the fundamental characteristics of biological synapses, including producing an excitatory postsynaptic current (EPSC), exhibiting a transition from short-term memory (STM) to long-term memory (LTM) states, and paired pulse facilitation (PPF), all of which are optically controllable. These junctions also exhibit photo-sensing properties and photo-controllable synaptic plasticity, meaning that they have similar functions as occur in the human brain and retina. Arrays fabricated from these junctions were found to function as image sensors that could provide an optical memory function and selectively memorize information depending on the relative importance of the data. These results are expected to assist in the realization of neuromorphic optical computers simulating human visual memory systems that are modulated by specific interests.
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Context.
The Event Horizon Telescope (EHT) will soon provide the first high-resolution images of the Galactic Centre supermassive black hole candidate Sagittarius A* (Sgr A
*
), enabling us to probe ...gravity in the strong-field regime. In addition to studying the accretion process in extreme environments, the obtained data and reconstructed images could be used to investigate the underlying spacetime structure. In its current configuration, EHT is able to distinguish between a rotating Kerr black hole and a horizon-less object such as a boson star. Future developments can increase the ability of EHT to tell different spacetimes apart.
Aims.
We investigate the capability of an advanced EHT concept, including an orbiting space antenna, to image and distinguish different spacetimes around Sgr A
*
.
Methods.
We used general-relativistic magneto-hydrodynamical simulations of accreting compact objects (Kerr and dilaton black holes as well as boson stars) and computed their radiative signatures via general-relativistic radiative transfer. To facilitate a comparison with upcoming and future EHT observations, we produced realistic synthetic data including the source variability, diffractive, and refractive scattering while incorporating the observing array, including a space antenna. From the generated synthetic observations, we dynamically reconstructed black hole shadow images using regularised maximum entropy methods. We employed a genetic algorithm to optimise the orbit of the space antenna with respect to improved imaging capabilities and
u
−
v
-plane coverage of the combined array (ground array and space antenna) and developed a new method to probe the source variability in Fourier space.
Results.
The inclusion of an orbiting space antenna improves the capability of EHT to distinguish the spin of Kerr black holes and dilaton black holes based on reconstructed radio images and complex visibilities.
The Magellanic Mopra Assessment (MAGMA) is a high angular resolution 12CO (J= 1 → 0) mapping survey of giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud ...using the Mopra Telescope. Here we report on the basic physical properties of 125 GMCs in the LMC that have been surveyed to date. The observed clouds exhibit scaling relations that are similar to those determined for Galactic GMCs, although LMC clouds have narrower linewidths and lower CO luminosities than Galactic clouds of a similar size. The average mass surface density of the LMC clouds is 50 M⊙ pc−2, approximately half that of GMCs in the inner Milky Way. We compare the properties of GMCs with and without signs of massive star formation, finding that non-star-forming GMCs have lower peak CO brightness than star-forming GMCs. We compare the properties of GMCs with estimates for local interstellar conditions: specifically, we investigate the H i column density, radiation field, stellar mass surface density and the external pressure. Very few cloud properties demonstrate a clear dependence on the environment; the exceptions are significant positive correlations between (i) the H i column density and the GMC velocity dispersion, (ii) the stellar mass surface density and the average peak CO brightness and (iii) the stellar mass surface density and the CO surface brightness. The molecular mass surface density of GMCs without signs of massive star formation shows no dependence on the local radiation field, which is inconsistent with the photoionization-regulated star formation theory proposed by McKee. We find some evidence that the mass surface density of the MAGMA clouds increases with the interstellar pressure, as proposed by Elmegreen, but the detailed predictions of this model are not fulfilled once estimates for the local radiation field, metallicity and GMC envelope mass are taken into account.
The authors evaluated the feasibility of MR permeability imaging by comparison with 11C-methionine-PET, FDG-PET, and DWI for differentiating radiation necrosis from recurrent tumors in 15 patients ...with 18 lesions following gamma knife radiosurgery. The area under the ROC curve for differentiating radiation necrosis from recurrent tumors was the best for the 11C-methionine ratio (0.90) followed by the contrast-enhancement ratio (0.81), maximum slope of increase (millimole/second) (0.80), and the initial area under the signal intensity–time curve (0.78). They conclude that PET using 11C-methionine may be superior to MR permeability imaging, ADC, and FDG-PET for differentiating radiation necrosis from recurrent tumors after gamma knife radiosurgery for metastatic brain tumors.BACKGROUND AND PURPOSE:In patients with metastatic brain tumors after gamma knife radiosurgery, the superiority of PET using 11C-methionine for differentiating radiation necrosis and recurrent tumors has been accepted. To evaluate the feasibility of MR permeability imaging, it was compared with PET using 11C-methionine, FDG-PET, and DWI for differentiating radiation necrosis from recurrent tumors.MATERIALS AND METHODS:The study analyzed 18 lesions from 15 patients with metastatic brain tumors who underwent gamma knife radiosurgery. Ten lesions were identified as recurrent tumors by an operation. In MR permeability imaging, the transfer constant between intra- and extravascular extracellular spaces (/minute), extravascular extracellular space, the transfer constant from the extravascular extracellular space to plasma (/minute), the initial area under the signal intensity–time curve, contrast-enhancement ratio, bolus arrival time (seconds), maximum slope of increase (millimole/second), and fractional plasma volume were calculated. ADC was also acquired. On both PET using 11C-methionine and FDG-PET, the ratio of the maximum standard uptake value of the lesion divided by the maximum standard uptake value of the symmetric site in the contralateral cerebral hemisphere was measured (11C-methionine ratio and FDG ratio, respectively). The receiver operating characteristic curve was used for analysis.RESULTS:The area under the receiver operating characteristic curve for differentiating radiation necrosis from recurrent tumors was the best for the 11C-methionine ratio (0.90) followed by the contrast-enhancement ratio (0.81), maximum slope of increase (millimole/second) (0.80), the initial area under the signal intensity–time curve (0.78), fractional plasma volume (0.76), bolus arrival time (seconds) (0.76), the transfer constant between intra- and extravascular extracellular spaces (/minute) (0.74), extravascular extracellular space (0.68), minimum ADC (0.60), the transfer constant from the extravascular extracellular space to plasma (/minute) (0.55), and the FDG-ratio (0.53). A significant difference in the 11C-methionine ratio (P < .01), contrast-enhancement ratio (P < .01), maximum slope of increase (millimole/second) (P < .05), and the initial area under the signal intensity–time curve (P < .05) was evident between radiation necrosis and recurrent tumor.CONCLUSIONS:The present study suggests that PET using 11C-methionine may be superior to MR permeability imaging, ADC, and FDG-PET for differentiating radiation necrosis from recurrent tumors after gamma knife radiosurgery for metastatic brain tumors.
Antipsychotic-induced metabolic adversities are often difficult to manage. Using concomitant medications to counteract these adversities may be a rational option.
To systematically determine the ...effectiveness of medications to counteract antipsychotic-induced metabolic adversities in patients with schizophrenia.
Published articles until November 2013 were searched using 5 electronic databases. Clinical trial registries were searched for unpublished trials.
Double-blind randomized placebo-controlled trials focusing on patients with schizophrenia were included if they evaluated the effects of concomitant medications on antipsychotic-induced metabolic adversities as a primary outcome.
Variables relating to participants, interventions, comparisons, outcomes, and study design were extracted. The primary outcome was change in body weight. Secondary outcomes included clinically relevant weight change, fasting glucose, hemoglobin A1c, fasting insulin, insulin resistance, cholesterol, and triglycerides.
Forty trials representing 19 unique interventions were included in this meta-analysis. Metformin was the most extensively studied drug in regard to body weight, the mean difference amounting to -3.17 kg (95% CI: -4.44 to -1.90 kg) compared to placebo. Pooled effects for topiramate, sibutramine, aripiprazole, and reboxetine were also different from placebo. Furthermore, metformin and rosiglitazone improved insulin resistance, while aripiprazole, metformin, and sibutramine decreased blood lipids.
When nonpharmacological strategies alone are insufficient, and switching antipsychotics to relatively weight-neutral agents is not feasible, the literature supports the use of concomitant metformin as first choice among pharmacological interventions to counteract antipsychotic-induced weight gain and other metabolic adversities in schizophrenia.
Abstract
Observations of the Galactic Center supermassive black hole Sagittarius A* (Sgr A*) with very long-baseline interferometry (VLBI) are affected by interstellar scattering along our line of ...sight. At long radio observing wavelengths (≲1 cm), the scattering heavily dominates image morphology. At 3.5 mm (86 GHz), the intrinsic source structure is no longer sub-dominant to scattering, and thus the intrinsic emission from Sgr A* is resolvable with the Global Millimeter VLBI Array (GMVA). Long-baseline detections to the phased Atacama Large Millimeter/submillimeter Array (ALMA) in 2017 provided new constraints on the intrinsic and scattering properties of Sgr A*, but the stochastic nature of the scattering Requires multiple observing epochs to reliably estimate its statistical properties. We present new observations with the GMVA+ALMA, taken in 2018, which confirm non-Gaussian structure in the scattered image seen in 2017. In particular, the ALMA–GBT baseline shows more flux density than expected for an anistropic Gaussian model, providing a tight constraint on the source size and an upper limit on the dissipation scale of interstellar turbulence. We find an intrinsic source extent along the minor axis of ∼100
μ
as both via extrapolation of longer wavelength scattering constraints and direct modeling of the 3.5 mm observations. Simultaneously fitting for the scattering parameters, we find an at-most modestly asymmetrical (major-to-minor axis ratio of 1.5 ± 0.2) intrinsic source morphology for Sgr A*.
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