It has recently been proposed that combining chirality with topological band theory results in a totally new class of fermions. Understanding how these unconventional quasiparticles propagate and ...interact remains largely unexplored so far. Here, we use scanning tunneling microscopy to visualize the electronic properties of the prototypical chiral topological semimetal PdGa. We reveal chiral quantum interference patterns of opposite spiraling directions for the two PdGa enantiomers, a direct manifestation of the change of sign of their Chern number. Additionally, we demonstrate that PdGa remains topologically non-trivial over a large energy range, experimentally detecting Fermi arcs in an energy window of more than 1.6 eV that is symmetrically centered around the Fermi level. These results are a consequence of the deep connection between chirality in real and reciprocal space in this class of materials, and, thereby, establish PdGa as an ideal topological chiral semimetal.
Flow-diverter treatment for previously stented aneurysms has been reported to be less effective and prone to complications. In this study, we evaluated the effectiveness and safety of flow diverters ...for recurrent aneurysms after stent-assisted coiling.
Patients who underwent flow-diverter placement for recurrent aneurysms after stent-assisted coiling between March 2015 and March 2019 were recruited. Clinical and radiographic characteristics and clinical and angiographic outcomes were retrospectively evaluated.
Among 133 patients who underwent flow-diverter insertion, 17 (male/female ratio = 5:12; mean age, 53.8 years) were treated for recurrent aneurysms after stent placement with (
= 16) or without (
= 1) coiling. Eight patients initially presented with subarachnoid hemorrhage; 7, with headache; and 2, with visual field defects. Angiographic morphology included large/giant saccular in 12 patients, dissecting in 2, fusiform in 1, traumatic pseudoaneurysm in 1, and ruptured blood blister-like aneurysm in 1. The duration between the first treatment and flow-diverter placement ranged from 2 weeks to 15 months (median, 6 months). Flow-diverter placement was successful in all cases without any complications. All patients had favorable outcomes (mRS, 0-2), without any newly appearing symptoms. Aneurysms were followed up with conventional angiography at least once in 6-18 months. Sixteen aneurysms showed complete occlusion, and 1 aneurysm was enlarged.
Results from this case series investigating flow-diverter placement for recurrent aneurysms after stent-assisted coiling suggested that the procedure is safe and effective. Further study in a larger population may be warranted.
Tropical cyclones (TCs) pose a significant threat to human health, and research is needed to identify high-risk subpopulations. We investigated whether hospitalization risks from TCs in Florida (FL), ...United States, varied across individuals and communities. We modeled the associations between all storms in FL from 1999 to 2016 and over 3.5 million Medicare hospitalizations for respiratory (RD) and cardiovascular disease (CVD). We estimated the relative risk (RR), comparing hospitalizations during TC-periods (2 days before to 7 days after) to matched non-TC-periods. We then separately modeled the associations in relation to individual and community characteristics. TCs were associated with elevated risk of RD hospitalizations (RR: 4.37, 95% CI: 3.08, 6.19), but not CVD (RR: 1.04, 95% CI: 0.87, 1.24). There was limited evidence of modification by individual characteristics (age, sex, or Medicaid eligibility); however, risks were elevated in communities with higher poverty or lower homeownership (for CVD hospitalizations) and in denser or more urban communities (for RD hospitalizations). More research is needed to understand the potential mechanisms and causal pathways that might account for the observed differences in the association between tropical cyclones and hospitalizations across communities.
Emergence agitation is common after nasal surgery. We investigated the effects of intraoperative dexmedetomidine infusion on emergence agitation and quality of recovery after nasal surgery in adult ...patients.
One hundred patients undergoing nasal surgery were randomized into two groups. The dexmedetomidine group (Group D, n=50) received dexmedetomidine infusion at a rate of 0.4 μg kg−1 h−1 from induction of anaesthesia until extubation, while the control group (Group C, n=50) received volume-matched normal saline infusion as placebo. Propofol (1.5–2 mg kg−1) and fentanyl (1 μg kg−1) were used for induction of anaesthesia, and desflurane was used for maintenance of anaesthesia. The incidence of agitation, haemodynamic parameters, and recovery characteristics were evaluated during emergence. A 40-item quality-of-recovery questionnaire (QoR-40) was provided to patients 24 h after surgery.
The incidence of agitation was lower in Group D than Group C (28 vs 52%, P=0.014). Mean arterial pressure and heart rate were more stable in Group D than in Group C during emergence (P<0.05). Time to extubation, bispectral index, and respiratory rate at extubation were similar between the groups. Global QoR-40 score at 24 h after surgery was higher in Group D (median range, 183 146 –198) compared with Group C (178 133–196) (P=0.041).
Intraoperative infusion of dexmedetomidine provided smooth and haemodynamically stable emergence. It also improved quality of recovery after nasal surgery.
Achieving complete recanalization with the front-line endovascular thrombectomy device improves the outcome of acute stroke. The aim of this study was to evaluate whether various thrombectomy ...techniques including contact aspiration, stent retriever thrombectomy, and combination therapy differ in first-pass effect and distal emboli in acute large-vessel occlusion simulated using 3D printed nontortuous and tortuous cerebrovascular anatomy models.
3D printed flow models were manufactured using angiographic data of nontortuous and acutely angulated tortuous vascular anatomy from real patients. Three thrombectomy techniques, contact aspiration, stent retriever, and combined methods, were tested under proximal protection with the balloon-guiding catheter. The first-pass effect and distal emboli rates were analyzed in addition to the thrombectomy-failure mechanisms of the respective techniques.
A total of 30 thrombectomy experiments were performed. The overall incidence of first-pass effect in the nontortuous and tortuous anatomy was 80.0% versus 46.7%. The overall incidence of distal emboli in the nontortuous and tortuous anatomy was 26.7% versus 46.7%. The contact aspiration technique showed better first-pass effect (80.0%) and distal emboli rates (20%) in the tortuous model compared with other techniques. The combined technique did not show remarkable superiority of the first-pass effect and distal emboli in either the nontortuous or tortuous anatomy. Shearing off of the thrombus was the main mechanism of thrombectomy failure in the combined group.
The tortuous vascular anatomy may worsen the first-pass effect and distal emboli rates. The combined techniques failed to show improvement in outcome due to the shearing-off phenomenon of the thrombus during retrieval.
Many interesting materials phenomena such as the emergence of high-Tc superconductivity in the cuprates and colossal magnetoresistance in the manganites arise out of a doping-driven competition ...between energetically similar ground states. Doped multiferroics present a tantalizing evolution of this generic concept of phase competition. Here, we present the observation of an electronic conductor-insulator transition by control of band-filling in the model antiferromagnetic ferroelectric BiFeO3 through Ca doping. Application of electric field enables us to control and manipulate this electronic transition to the extent that a p-n junction can be created, erased and inverted in this material. A 'dome-like' feature in the doping dependence of the ferroelectric transition is observed around a Ca concentration of approximately 1/8, where a new pseudo-tetragonal phase appears and the electric modulation of conduction is optimized. Possible mechanisms for the observed effects are discussed on the basis of the interplay of ionic and electronic conduction. This observation opens the door to merging magnetoelectrics and magnetoelectronics at room temperature by combining electronic conduction with electric and magnetic degrees of freedom already present in the multiferroic BiFeO3.
Abstract This study examined whether individual differences in aerobic fitness are associated with differences in activation of cognitive control brain networks in preadolescent children. As ...expected, children performed worse on a measure of cognitive control compared with a group of young adults. However, individual differences in aerobic fitness were associated with cognitive control performance among children. Lower-fit children had disproportionate performance cost in accuracy with increasing task difficulty, relative to higher-fit children. Brain activation was compared between performance-matched groups of lower- and higher-fit children. Fitness groups differed in brain activity for regions associated with response execution and inhibition, task set maintenance, and top-down regulation. Overall, differing activation patterns coupled with different patterns of brain-behavior correlations suggest an important role of aerobic fitness in modulating task strategy and the efficiency of neural networks that implement cognitive control in preadolescent children.
Both IDH1 mutation and MGMT promoter methylation are associated with longer survival. We investigated the ability of imaging correlates to serve as noninvasive biomarkers for these molecularly ...defined GBM subtypes.
MR imaging from 202 patients with GBM was retrospectively assessed for nonenhancing tumor and edema among other imaging features. IDH1 mutational and MGMT promoter methylation status were determined by DNA sequencing and methylation-specific PCR, respectively. Overall survival was determined by using a multivariate Cox model and the Kaplan-Meier method with a log rank test. A logistic regression model followed by ROC analysis was used to classify the IDH1 mutation and methylation status by using imaging features.
MGMT promoter methylation and IDH1 mutation were associated with longer median survival. Edema levels stratified survival for methylated but not unmethylated tumors. Median survival for methylated tumors with little/no edema was 2476 days (95% CI, 795), compared with 586 days (95% CI, 507-654) for unmethylated tumors or tumors with edema. All IDH1 mutant tumors were nCET positive, and most (11/14, 79%) were located in the frontal lobe. Imaging features including larger tumor size and nCET could be used to determine IDH1 mutational status with 97.5% accuracy, but poorly predicted MGMT promoter methylation.
Imaging features are potentially predictive of IDH1 mutational status but were poorly correlated with MGMT promoter methylation. Edema stratifies survival in MGMT promoter methylated but not in unmethylated tumors; patients with methylated tumors with little or no edema have particularly long survival.
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