bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Household Income on Short-Term Outcomes Following Cerebellopontine Angle Tumor Resection
Authors: Huang Vincent , Miranda Stephen P. , Dimentberg Ryan , Shultz Kaitlyn , McClintock Scott D. , Malhotra Neil R. 
Published: February 2021

Abstract
Objectives The objective of this study is to elucidate the impact of income on short-term outcomes in a cerebellopontine angle (CPA) tumor resection population.
Design This is a retrospective regression analysis.
Setting This study was done at a single, multihospital, urban academic medical center.
Participants Over 6 years (from June 7, 2013, to April 24, 2019), 277 consecutive CPA tumor cases were reviewed.
Main Outcome Measures Outcomes studied included readmission, emergency department evaluation, unplanned return to surgery, return to surgery after index admission, and mortality. Univariate analysis was conducted among the entire population with significance set at a p-value <0.05. The population was divided into quartiles based on median household income and univariate analysis conducted between the lowest (quartile 1 [Q1]) and highest (quartile 4 [Q4]) socioeconomic quartiles, with significance set at a p-value <0.05. Stepwise regression was conducted to determine the correlations among study variables and to identify confounding factors.
Results Regression analysis of 273 patients demonstrated decreased rates of unplanned reoperation (p = 0.015) and reoperation after index admission (p = 0.035) at 30 days with higher standardized income. Logistic regression between the lowest (Q1) and highest (Q4) socioeconomic quartiles demonstrated decreased unplanned reoperation (p = 0.045) and decreasing but not significant reoperation after index admission (p = 0.15) for Q4 patients. No significant difference was observed for other metrics of morbidity and mortality.
Conclusion Higher socioeconomic status is associated with decreased risk of unplanned reoperation following CPA tumor resection.
Reducing ICU Length of Stay: The Impact of a Multidisciplinary Perioperative Pathway in Vestibular Schwannoma
Authors: Yawn Robert J. , Nassiri Ashley M. , Harris Jacqueline E. , Manzoor Nauman F. , Godil Saniya , Haynes David S. , Bennett Marc L. , Weaver Sheena M. 
Published: February 2021

Abstract
Objective This study was aimed to evaluate the impact of a multidisciplinary perioperative pathway on length of stay (LOS) and postoperative outcomes after vestibular schwannoma surgery.
Setting This study was conducted in a tertiary skull base center.
Main Outcome Measures The impact of the pathway on intensive care unit (ICU) LOS was evaluated as the primary outcome measure of the study. Overall resource LOS, postoperative complications, and readmission rates were also evaluated as secondary outcome measures.
Methods Present study is a retrospective review.
Results A universally adopted perioperative pathway was developed to include standardization of preoperative education and expectations, intraoperative anesthetic delivery, postoperative nursing education, postoperative rehabilitation, and utilization of stepdown and surgical floor units after ICU stay. Outcomes were measured for 95 consecutive adult patients who underwent surgical resection for vestibular schwannoma (40 cases before implementation of the perioperative pathway and 55 cases after implementation). There were no significant differences in the two groups with regard to tumor size, operative time, or medical comorbidities. The mean ICU LOS decreased from 2.1 in the preimplementation group to 1.6 days in the postimplementation group (p = 0.02). There were no significant differences in overall resource LOS postoperative complications or readmission rates between groups.
Conclusion Multidisciplinary, perioperative neurotologic pathways can be effective in lowering ICU LOS in patients undergoing vestibular schwannoma surgery without compromising quality of care. Further research is needed to continue to sustain and continuously improve these and other measures, while continuing to provide high-quality care to this patient population.
Transcatheter Mitral Valve Replacement: A Novel Anchor Technology
Authors: Liu Yazhou , Lutter Georg , Knueppel Philipp , Frank Derk , Lozonschi Lucian , Berndt Rouven , Attmann Tim , Puehler Thomas 
Published: February 2021

Abstract
Background Mitral valved stents tend to migrate or to develop paravalvular leakage due to high–left ventricular pressure in this cavity. Thus, this study describes a newly developed mitral valved stent anchoring technology.
Methods Based on an existing mitral valved stent, four anchoring units with curved surgical needles were designed and fabricated using three-dimensional (3D) software and print technology. Mitral nitinol stents assembled with four anchoring units were successively fixed on 10 porcine annuli. Mechanical tests were performed with a tensile force test system and recorded the tension forces of the 10 nitinol stents on the annulus.
Results The average maximum force was 28.3 ± 5.21 N, the lowest was 21.7 N, and the highest was 38.6 N until the stent lost contact with the annulus; for the break force (zero movement of stent from annulus), the average value was 18.5 ± 6.7 N with a maximum value of 26.9 N and a minimum value of 6.07 N. It was additionally observed that the puncture needles of the anchoring units passed into the mitral annulus in all 10 hearts and further penetrated the myocardium in only one additional heart. The anchoring units enhanced the tightness of the mitral valved stent and did not destroy the circumflex coronary artery, coronary sinus, right atrium, aortic root, or the left ventricular outflow tract.
Conclusion The new anchoring units for mitral nitinol stents were produced with 3D software and printing technology; with this new type of anchoring technology, the mitral valved stent can be tightly fixed toward the mitral annulus.
Reconsidering the Ostrogradsky theorem: higher-derivatives Lagrangians, ghosts and degeneracy
Authors: Ganz Alexander , Noui Karim 
Published: February 2021

Abstract
We review the fate of the Ostrogradsky ghost in higher-order theories. We start by recalling the original Ostrogradsky theorem and illustrate, in the context of classical mechanics, how higher-derivatives Lagrangians lead to unbounded Hamiltonians and then lead to (classical and quantum) instabilities. Then, we extend the Ostrogradsky theorem to higher-derivatives theories of several dynamical variables and show the possibility to evade the Ostrogradsky instability when the Lagrangian is ‘degenerate’, still in the context of classical mechanics. In particular, we explain why higher-derivatives Lagrangians and/or higher-derivatives Euler–Lagrange equations do not necessarily lead to the propagation of an Ostrogradsky ghost. We also study some quantum aspects and illustrate how the Ostrogradsky instability shows up at the quantum level. Finally, we generalize our analysis to the case of higher order covariant theories where, as the Hamiltonian is vanishing and thus bounded, the question of Ostrogradsky instabilities is subtler.
Ghost scalar field dark energy models from an extended Kaluza–Klein perspective
Authors: Korunur Murat 
Published: February 2021

Abstract
Reconstruction process of scalar field models (quintessence, tachyon, dilaton and K-essence), which can be performed by making use of some dark energy density definitions such as holographic, Ricci, new agegraphic and ghost types proposals, has been an interesting and very attractive area to many physicists in literature. In this work, in a five-dimensional framework, we establish a correspondence between the quintessence, tachyon and the dilaton type scalar field definitions and the generalized ghost dark energy model by considering the extended form of the Kaluza–Klein (EKK) gravity. Accordingly, we numerically study the associated equation of state parameters, as well as their kinetic energy and scalar potential terms.
Simulating quantum interference effects in the fluorescence of a V-system with perpendicular dipole moments
Authors: Crispin H B 
Published: February 2021

Abstract
We present a scheme that enables the observation of interference effects in the resonance fluorescence of a V-type atom with orthogonal dipole moments. Specifically, we consider the atomic configuration of a J
g = 0 to J
e = 1 transition driven by a single laser field. By employing polarization-sensitive detection in such a way that the light emitted on the two transitions become indistinguishable, we show that one can simulate the effect of vacuum-induced coherence on the resonance fluorescence of this system. In addition, we demonstrate the possibility of realizing atomic transitions with both parallel and antiparallel dipole moments and their effects on the fluorescence spectrum. The interference induced leads to interesting features in the fluorescence spectrum such as asymmetric spectral peaks, enhancement and suppression of the sidebands, and disappearance of fluorescence in the particular direction of detection. The numerical results are understood in the context of the dressed states of the combined atom–field system.
Deposition of oxygenated hydrocarbons in a packed-bed plasma reactor during the oxidation of toluene: influence of applied voltage
Authors: Mujahid Zakaulislam , Oteef Mohammed D Y , Tu Xin , Schulze Julian 
Published: February 2021

Abstract
Packed-bed plasma reactors (PBPRs) have been investigated extensively to study the abatement of volatile organic compounds such as toluene. Previous studies have reported that the applied voltage (or power) is a critical parameter that affects the performance of PBPRs. However, the origin of this change in performance is not well understood. A conventional PBPR contains irregularly filled dielectric pellets that generate several micro- and mesoscopic voids in between the pellets and between pellets and dielectric walls where filamentary discharges are generated. These voids are optically inaccessible and the reaction products are often generated in gaseous form; therefore, the location of the chemical reactions within these voids could not be studied. In this work, we have qualitatively investigated the influence of the applied voltage on the locations of chemical reactions in the void using toluene oxidation as an example. Using a single layer of regularly arranged hemispherical pellets and a transparent electrode in a PBPR, the plasma generation within these voids became optically accessible. The operating conditions were tailored to enhance the deposition of solid or liquid products on the glass beads to understand the locations of chemical reactions. The intensified charged coupled device camera images of the discharge through the transparent electrode show that the distribution of plasma emission changes with the applied voltage amplitude. The distribution of the deposited/condensed solid/liquid intermediates and reaction products was found to match the plasma emission. The analysis of the reaction products and deposition/condensation locations indicates that short-living species such as energetic electrons, OH and O radicals might play an essential role in the formation of deposited chemicals on the glass beads.
Investigation of mode couplings between core and cladding of terahertz anti-resonant fibres
Authors: Sun Shuai , Shi Wei , Sheng Quan , Zhang Yao , Yan Zhongbao , Zhang Junxiang , Shi Chaodu , Zhang Guizhong , Yao Jianquan 
Published: February 2021

Abstract
In this study, we numerically investigated mode couplings in terahertz (THz) anti-resonant fibres (ARFs) and found that the mode couplings were determined by the diameter ratio of the core and cladding tubes. Moreover, the optimal diameter ratio was affected by the change in the number of cladding tubes, bent radii and the refractive index of the gas filled in fibre. Mode couplings provide novel theories for fundamental mode suppression and higher-order mode suppression. In THz ARFs, taking the semielliptical tubes as anti-resonant elements can significantly improve the suppression ability of mode couplings.
Improving the phase stability of CsPbI3 nanocrystalline films via polyvinylpyrrolidone additive engineering for photodetector application
Authors: Yang Peixin , Ullah Saad , Wang Jiaming , Liu Linlin , Yang Shi-E , Xia Tianyu , Guo Haizhong , Chen Yongsheng 
Published: February 2021

Abstract
CsPbI3 perovskite materials have triggered enormous research attention as promising light-harvesting or fluorescent materials, owing to their high photoluminescence quantum yields, narrow photoluminescence (PL) emission spectra and excellent photophysical properties based on the quantum confinement effect. However, the formation of desirable black-phase CsPbI3 requires complex processing at higher annealing temperatures and upon formation it suffers from instability issues at room temperature, hindering its potential for optoelectronic application. In this work, using polyvinylpyrrolidone (PVP) as an additive, highly stable CsPbI3 nanocrystalline films are prepared at a low annealing temperature of 180 °C via a one-step spin-coating method. It is found that the PVP additive not only improves the stability by inhibiting the transition of CsPbI3 from α- to δ-phase at room temperature but also influences the crystallization dynamics. In addition, the PL intensity is substantially enhanced due to the suppression of non-recombination sites with PVP. With a PVP concentration of 12 wt%, a charge carrier lifetime of 43.99 ns is obtained and a palpable orange-yellow color is formed irradiated in plane by a green laser. Finally, a simple photodetector is fabricated with a structure of FTO/PVP-CsPbI3/Ag, exhibiting excellent photodetecting response with increased PVP concentration in the film. These results suggest that PVP-CsPbI3 has strong research and application potential in the future in optoelectronic devices.
Fabrication and investigation of quaternary Ag–In–Zn–S quantum dots-based memristors with ultralow power and multiple resistive switching behaviors
Authors: He Nan , Tao Langyi , Zhang Qiangqiang , Liu Xiaoyan , Lian Xiaojuan , Hu Er-Tao , Sheng Yang , Xu Feng , Tong Yi 
Published: February 2021

Abstract
Quaternary Ag–In–Zn–S (AIZS) quantum dots (QDs) play critical roles in various applications since they have advantages of combining superior optical and electrical features, such as tunable fluorescence emission and high carrier mobilities. However, the application of semiconductor AIZS QDs in brain-inspired devices (e.g. memristor) has been rarely reported. In this work, the tunable volatile threshold switching (TS) and non-volatile memory switching (MS) behaviors have been obtained in a memristor composed of AIZS QDs by regulating the magnitude of compliance current. Additionally, the innovative Ag/AIZS structure devices without traditional oxide layer exhibit low operation voltage (∼0.25 V) and programming current (100 nA) under the TS mode. Moreover, the devices achieve reproducible bipolar resistive switching (RS) behaviors with large ON/OFF ratio of ∼105, ultralow power consumption of ∼10–10 W, and good device-to-device uniformity under the MS mode. Furthermore, the charge transport mechanisms of the high- and low-resistance states under the positive and negative bias have been analyzed with space-charge-limited-current and filament conduction models, respectively. This work not only validates the potential of AIZS QDs acting as dielectric layer in RS devices but also provides a new guideline for designing ultralow power and multiple RS characteristics devices.
A systematic evaluation of learning rate policies in training CNNs for brain tumor segmentation
Authors: Bukhari Syed Talha , Mohy-ud-Din Hassan 
Published: February 2021

Abstract
Convolutional neural networks (CNNs) have recently emerged as a powerful approach for automatic segmentation of brain tumor subregions on 3D multi-parametric MRI scans. Learning rate is a crucial hyperparameter in the training of CNNs, impacting the performance of the learned model. Different learning rate policies trace unique trajectories in the optimization landscape that converge to local minima with varying generalization properties. In this work, we empirically evaluated nine learning rate policy-optimizer pairs with two state-of-the-art architectures, namely 2D slice-based U-Net and 3D DeepMedicRes, on an augmented brain tumor dataset of 534 subjects. Segmentation performance was quantified in terms of Dice similarity coefficient and Hausdorff distance metrics. The policies were ranked based on the final ranking score (FRS) employed by the BraTS challenge, with the statistical significance of the rankings evaluated by random permutation test. For 2D slice-based U-Net architecture, an overall ranking of learning rate policies showed that the polynomial decay policy with Adam optimizer significantly outperformed other policies for the task of individual and hierarchical segmentation of tumor subregions (p < 10−4). For 3D segment-based DeepMedicRes architecture, polynomial decay policy with Adam optimizer performed significantly better than all other policies, with the exception of polynomial decay with SGD optimizer for the same task (p < 10−4). Based on the FRS, polynomial decay policy with Adam and SGD optimizer occupied the top two positions respectively, but the difference was not statistically significant (p > 0.3). These findings were also validated on the BraTS 2019 Validation dataset which comprised of an additional 125 subjects.
Rhombohedral symmetry in GaAs1−

x
N
x
nanostructures
Authors: Zelaya-Angel O , Jiménez-Sandoval S , Alvarez-Fregoso O , Mendoza-Alvarez J G , Gómez-Herrera M L , Cardona-Bedoya J , Huerta-Ruelas J 
Published: February 2021

Abstract
Nanocrystalline structures of GaAs1−x
N
x
thin films were prepared on 7059 Corning glass substrates by means of an RF magnetron sputtering system using a GaAs target and N2 as ambient-gas, at several values of substrate temperature (T
s). The range of T
s was chosen from room temperature to 400 °C. The nitrogen concentration into the GaAsN layers is (1.0% ± 0.2%). The average energy band gap of the GaAsN nanostructures, calculated from their optical absorption spectra, is 2.9 ± 0.2 eV. The Raman scattering spectra exhibit vibrational modes associated to the rhombohedral phase due to the crystalline structural transformation from the zincblende (ZB)-GaAs caused by the introduction of N into the lattice. From x-ray diffraction (XRD) patterns the ZB structure was identified with two additional pairs of peaks which were associated to two types of cubic to rhombohedral crystalline phase changes of the material. One type has a low deformation to a moderately elongated unit cell, and the second type has a higher deformation to a more elongated unit cell. The rhombohedral symmetry of the crystalline lattice in the GaAsN nanostructures has been calculated from XRD data to confirm experimental evidences. The total average grain size was determined from the Scherrer formula: 3.3 ± 1.2 nm. The photoluminescence spectra are characterized by a very broad emission band which encompasses photon energies from near infrared to UV (775–310 nm, i.e. 1.6–4.0 eV).
Semi-active vibration control based on switchable transfer of bending moments: study and experimental validation of control performance
Authors: Mikułowski Grzegorz , Popławski Błażej , Jankowski Łukasz 
Published: February 2021

Abstract
This paper presents an experimental approach to assessment of semi-active vibration control systems based on the Prestress–Accumulation Release concept. The objectives are threefold: (1) to introduce an experimental validation method for control algorithms based on switchable transfer of moments, (2) to propose a method to assess experimentally the control effects on structural dynamic response under several types of excitation, and (3) to propose an approach for adequate sensor placement. A laboratory frame demonstrator equipped with dedicated semi-active nodes is used. The proposed approach is based on spectral responses and modal analysis. According to the presented findings, the investigated control is effective in reducing the vibration level while keeping the structural dynamic stiffness at a proper level. The investigation is conducted in the case of free response, as well as responses to impact loading and random excitation. The results confirm the accuracy of the adopted algorithm parameters and reveal the sensor locations that provide the best control effectiveness.
Frequency dependent wave routing based on dual-band valley-Hall topological photonic crystal
Authors: Wei Guo-Chao , Liu Zhen-Zhen , Zhang Da-Sen , Xiao Jun-Jun 
Published: February 2021

Abstract
Previous studies on the propagation direction of valley topological edge states mainly focus on the matching between orbital angular momentum of the excitation source and specific pseudo-spin state of valley edge mode at certain frequency that falls in the bandgap of the topologically distinct bulk components. In this work, we propose topological photonic crystals (PCs) hosting two topological protected bandgaps. It is shown that by constructing the interface between different PC structures with distinct topological phase, edge states can be engineered inside these two bandgaps, which provides a convenient way to achieve flexible wave routing. Particularly, we study three types of meta-structures consisting of these PCs in which the valley edge states routing path highly depends on the operating frequency and inputting port of the excitation source. Our study provides an alternative way in designing topological devices such as wave splitters and frequency division devices.
Probing band-center anomaly with the Kernel polynomial method
Authors: Khan N A , Amin Syed Tahir 
Published: February 2021

Abstract
We investigate the anomalous behavior of localization length of a non-interacting one-dimensional Anderson model at zero temperature. We report numerical calculations of the Thouless expression of localization length, based on the Kernel polynomial method (KPM), which has an


(
N
)

computational complexity, where N is the system size. The KPM results show excellent agreement with perturbative results in a large system size limit, confirming the validity of the Thouless formula. In the perturbative regime, we show that the KPM approximation of the Thouless expression produces the correct localization length at the band center in the thermodynamic limit. The Thouless expression relates localization length in terms of density of states in a one-dimensional disordered system. By calculating the KPM estimates of the density of states, we find a cusp-like behavior around the band center in the perturbative regime. This cusp-like singularity can not be obtained by approximate analytical calculations within the second-order approximations, reflects the band-center anomaly.