The rotation curve (RC) of the Milky Way out to ~100 kpc has been constructed using ~16,000 primary red clump giants (PRCGs) in the outer disc selected from the LAMOST Spectroscopic Survey of the ...Galactic Anti-centre (LSS-GAC) and the Sloan Digital Sky Survey (SDSS)-III/APOGEE survey, combined with ~5700 halo K giants (HKGs) selected from the SDSS/SEGUE survey. To derive the RC, the PRCG sample of the warm disc population and the HKG sample of halo stellar population are, respectively, analysed using a kinematical model allowing for the asymmetric drift corrections and re-analysed using the spherical Jeans equation along with measurements of the anisotropic parameter beta currently available. The typical uncertainties of RC derived from the PRCG and HKG samples are, respectively, 5-7 km s super( -1) and several tens km s super( -1). We determine a circular velocity at the solar position, ... and an azimuthal peculiar speed of the Sun, ..., both in good agreement with the previous determinations. The newly constructed RC has a generally flat value of 240 km s super( -1) within a Galactocentric distance rof 25 kpc and then decreases steadily to 150 km s super( -1) at r ~ 100 kpc. On top of this overall trend, the RC exhibits two prominent localized dips, one at r ~ 11 kpc and another at r ~ 19 kpc. From the newly constructed RC, combined with other constraints, we have built a parametrized mass model for the Galaxy, yielding a virial mass of the Milky Way's dark matter halo of ... and a local dark matter density, ... (ProQuest: ... denotes formulae/symbols omitted.)
The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) and first-principles calculations. The experiments show ...that, surprisingly, although SnTe is closer to the ferroelectric instability, phonon spectra in PbTe exhibit a more anharmonic character. This behavior is reproduced in first-principles calculations of the temperature-dependent phonon self-energy. Our simulations reveal how the nesting of phonon dispersions induces prominent features in the self-energy, which account for the measured INS spectra and their temperature dependence. We establish that the phase space for three-phonon scattering processes, combined with the proximity to the lattice instability, is the mechanism determining the complex spectrum of the transverse-optic ferroelectric mode.
Abstract
We present the second release of value-added catalogues of the LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC DR2). The catalogues present values of radial velocity Vr, ...atmospheric parameters – effective temperature Teff, surface gravity log g, metallicity Fe/H, α-element to iron (metal) abundance ratio α/Fe (α/M), elemental abundances C/H and N/H and absolute magnitudes MV and $M_{K_{\rm s}}$ deduced from 1.8 million spectra of 1.4 million unique stars targeted by the LSS-GAC since 2011 September until 2014 June. The catalogues also give values of interstellar reddening, distance and orbital parameters determined with a variety of techniques, as well as proper motions and multiband photometry from the far-UV to the mid-IR collected from the literature and various surveys. Accuracies of radial velocities reach 5 km s−1 for the late-type stars, and those of distance estimates range between 10 and 30 per cent, depending on the spectral signal-to-noise ratios. Precisions of Fe/H, C/H and N/H estimates reach 0.1 dex, and those of α/Fe and α/M reach 0.05 dex. The large number of stars, the contiguous sky coverage, the simple yet non-trivial target selection function and the robust estimates of stellar radial velocities and atmospheric parameters, distances and elemental abundances make the catalogues a valuable data set to study the structure and evolution of the Galaxy, especially the solar-neighbourhood and the outer disc.
Summary Objective Chitosan has been widely used as an injectable scaffold in cartilage tissue engineering due to its characteristic biocompatibility and biodegradability. In this study, chitosan was ...used in its hydrogel form as a scaffold for chondrocytes that act to reconstruct tissue-engineered cartilage and repair articular cartilage defects in the sheep model. This study aims to find a novel way to apply chitosan in cartilage tissue engineering. Methods Temperature-responsive chitosan hydrogels were prepared by combining chitosan, β-sodium glycerophosphate (GP) and hydroxyethyl cellulose (HEC). Tissue-engineered cartilage reconstructions were made in vitro by mixing sheep chondrocytes with a chitosan hydrogel. Cell survival and matrix accumulation were analyzed after 3 weeks in culture. To collect data for in vivo repair, reconstructions cultured for 1 day were transplanted to the freshly prepared defects of the articular cartilage of sheep. Then at both 12 and 24 weeks after transplantation, the grafts were extracted and analyzed histologically and immunohistochemically. Results The results showed that the chondrocytes in the reconstructed cartilage survived and retained their ability to secrete matrix when cultured in vitro . Transplanted in vivo , the reconstructions repaired cartilage defects completely within 24 weeks. The implantation of chitosan hydrogels without chondrocytes also helps to repair cartilage defects. Conclusions The chitosan-based hydrogel could support matrix accumulation of chondrocytes and could repair sheep cartilage defects in 24 weeks. This study showcased the success of a new technique in its ability to repair articular cartilage defects.
The association between infarct location and hemorrhagic transformation of acute ischemic stroke after mechanical thrombectomy is not understood. We aimed to evaluate the association between ...CTP-based ischemic core variables at admission and hemorrhagic transformation after a successful thrombectomy.
We retrospectively analyzed patients who underwent endovascular thrombectomy for acute anterior circulation large-vessel occlusion between October 2019 and June 2021. We enrolled 146 patients with visible ischemic core on pretreatment CTP who had successful reperfusion. The ischemic core infarct territories were classified into the cortical and subcortical areas and then qualitatively and quantitatively analyzed by CTP. Logistic regression and receiver operating characteristic curve analyses were performed to determine the association between ischemic core variables and hemorrhagic transformation.
Of the 146 patients analyzed, 72 (49.3%) had hemorrhagic transformation and 23 (15.8%) had symptomatic intracerebral hemorrhage. Multivariate analysis showed that subcortical infarcts were independently associated with hemorrhagic transformation (OR, 8.06; 95% CI, 2.31-28.10;
= .001) and subcortical infarct volume was independently linked to symptomatic intracerebral hemorrhage (OR, 1.05; 95% CI, 1.01-1.09;
= .039). The receiver operating characteristic curve indicated that subcortical infarcts can predict hemorrhagic transformation accurately (area under the curve = 0.755; 95% CI, 0.68-0.82;
< .001) and subcortical infarct volume can predict symptomatic intracerebral hemorrhage (area under the curve = 0.694; 95% CI, 0.61-0.77;
= .002).
Subcortical infarcts seen on CTP at admission are associated with hemorrhagic transformation in patients after successful thrombectomy, and subcortical infarct volume may influence the risk of symptomatic intracerebral hemorrhage.
Abstract
Spin-valley locking in monolayer transition metal dichalcogenides has attracted enormous interest, since it offers potential for valleytronic and optoelectronic applications. Such an exotic ...electronic state has sparsely been seen in bulk materials. Here, we report spin-valley locking in a Dirac semimetal BaMnSb
2
. This is revealed by comprehensive studies using first principles calculations, tight-binding and effective model analyses, angle-resolved photoemission spectroscopy measurements. Moreover, this material also exhibits a stacked quantum Hall effect (QHE). The spin-valley degeneracy extracted from the QHE is close to 2. This result, together with the Landau level spin splitting, further confirms the spin-valley locking picture. In the extreme quantum limit, we also observed a plateau in the
z
-axis resistance, suggestive of a two-dimensional chiral surface state present in the quantum Hall state. These findings establish BaMnSb
2
as a rare platform for exploring coupled spin and valley physics in bulk single crystals and accessing 3D interacting topological states.
To describe the experience of endovascular treatment (EVT) of acute ischaemic stroke caused by isolated internal carotid artery (ICA) occlusion, with emphasis on treatment strategies, outcomes, and ...prognostic factors.
A retrospective examination was performed of 66 consecutive patients with acute moderate-to-severe stroke who underwent EVT for isolated ICA occlusion from July 2016 to June 2021. The modified thrombolysis in cerebral ischaemia (mTICI) score was used to evaluate reperfusion outcomes. A multivariate analysis was performed to identify risk factors associated with poor 90-day outcome (modified Rankin Scale mRS 3–6).
The National Institutes of Health Stroke Scale (NIHSS) median score of the 66 patients at admission was 15. Twelve patients (18.2%) showed thrombus migration to the M1 segment or proximal M2 during EVT and underwent additional intracranial thrombectomy. Successful reperfusion (mTICI 2b–3) was achieved in 60 patients (90.9%) and complete reperfusion (mTICI 3) in 42 (63.6%). A poor functional outcome was seen in 27 patients (40.9%). The rate of 90-day mortality was 9.1% (6/66). Higher NIHSS scores and a lower Alberta Stroke Program Early CT Score (ASPECTS) were independently associated with poor outcomes. Complete reperfusion was the only treatment factor with a significant predictive value (adjusted odds ratio OR 0.03; 95% CI = 0.01 to 0.25; p=0.001).
Endovascular therapy is safe and effective in patients with acute ischaemic stroke due to isolated ICA occlusion. Prevention of thrombus migration and complete reperfusion should be the aim of EVT.
•Thrombus migration is common during thrombectomy for isolated ICA occlusion.•Complete reperfusion should be the aim of thrombectomy for isolated ICA occlusion.•Addition of data helps guide treatment for isolated ICA occlusion.
Endovascular recanalization has been attempted in patients with symptomatic chronic ICA occlusion, however, the heterogeneity of recanalization outcomes and the perioperative complications present ...challenges for the clinical application. Our aim was to evaluate the safety and efficacy of endovascular recanalization for symptomatic chronic ICA occlusion and identify potential predictors for successful recanalization.
This study included 47 consecutive patients with symptomatic chronic ICA occlusion who underwent endovascular recanalization at our institution. Patients' clinical information, radiologic characteristics, procedural results, and outcomes were recorded. Factors related to technical success were analyzed by univariate and multivariate analyses.
The technical success rate was 74.5% (35/47); 12.8% of patients (6/47) experienced intraoperative complications, but none had permanent neurologic deficits. Three months after recanalization, 21 of the 29 recanalized patients (72.4%) and 3 of the 10 failed patients (30.0%) demonstrated improved mRS scores. Restenosis or re-occlusion occurred in 12.9% of patients (4/31) with successful recanalization. Multivariate analysis showed that tapered or blunt stump (
= .016), distal ICA occlusion segment (below the cavernous segment versus at or above the ophthalmic segment,
= .003; at the cavernous or clinoid segment versus at or above the ophthalmic segment,
= .027), and radiologic occlusion to recanalization of ≤3 months (
= .044) were significantly associated with successful recanalization. Patients were assigned points according to the coefficients of the prediction model, and the technical success rates were 0%, 46.2%, 90.5%, and 100% in patients with 1, 2, 3, and 4 points, respectively.
Endovascular recanalization is a safe and effective treatment for symptomatic chronic ICA occlusion in selected patients. A residual stump, low levels of the distal ICA occlusion segment, and a short radiologic occlusion time were identified as positive predictors of technical success.
Abstract
Magnetization plateaus in quantum magnets—where bosonic quasiparticles crystallize into emergent spin superlattices—are spectacular yet simple examples of collective quantum phenomena ...escaping classical description. While magnetization plateaus have been observed in a number of spin-1/2 antiferromagnets, the description of their magnetic excitations remains an open theoretical and experimental challenge. Here, we investigate the dynamical properties of the triangular-lattice spin-1/2 antiferromagnet Ba
3
CoSb
2
O
9
in its one-third magnetization plateau phase using a combination of nonlinear spin-wave theory and neutron scattering measurements. The agreement between our theoretical treatment and the experimental data demonstrates that magnons behave semiclassically in the plateau in spite of the purely quantum origin of the underlying magnetic structure. This allows for a quantitative determination of Ba
3
CoSb
2
O
9
exchange parameters. We discuss the implication of our results to the deviations from semiclassical behavior observed in zero-field spin dynamics of the same material and conclude they must have an intrinsic origin.
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