bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical and experimental evidence for a new interpretation of residence times in space
Authors: Vogt A. , Engelbrecht N. Eugene , Heber B. , Kopp A. , Herbst K.
Published: September 2021

Aims. We investigate the energy dependence of Jovian electron residence times, which allows for a deeper understanding of adiabatic energy changes that occur during charged particle transport, as well as of their significance for simulation approaches. Thereby we seek to further validate an improved approach to estimate residence times numerically by investigating the implications on previous analytical approaches and possible effects detectable by spacecraft data.

Methods. Utilising a propagation model based on a stochastic differential equation (SDE) solver written in CUDA, residence times for Jovian electrons were calculated over the whole energy range dominated by the Jovian electron source spectrum. We analysed the interdependences both with the magnetic connection between the observer and the source as well as between the distribution of the exit (simulation) times and the resulting residence times.

Results. We point out a linear relation between the residence time for different kinetic energies and the longitudinal shift of the 13 month periodicity typically observed for Jovian electrons and discuss the applicability of these findings to data. Furthermore, we utilise our finding that the simulated residence times are approximately linearly related to the energy loss for Jovian and Galactic electrons, and we develop an improved analytical estimation in agreement with the numerical residence time and the longitudinal shift observed by measurements.
Decoding the morphological evolution of open clusters
Authors: Hu Qingshun , Zhang Yu , Esamdin Ali
Published: September 2021

Context. The properties of open clusters such as metallicity, age, and morphology are useful tools in studies of the dynamic evolution of open clusters. The morphology of open clusters can help us better understand the evolution of such structures.

Aims. We aim to analyze the morphological evolution of 1256 open clusters by combining the shapes of the sample clusters in the proper motion space with their morphology in the two-dimensional spherical Galactic coordinate system, providing their shape parameters based on a member catalog derived from Gaia Second Data Release as well as data from the literature.

Methods. We applied a combination of a nonparametric bivariate density estimation with the least square ellipse fitting to derive the shape parameters of the sample clusters.

Results. We derived the shape parameters of the sample clusters in the two-dimensional spherical Galactic coordinate system and that of the proper motion space. By analyzing the dislocation of the sample clusters, we find that the dislocation, d, is related to the X-axis pointing toward the Galactic center, Y-axis pointing in the direction of Galactic rotation, and the Z-axis (log(|H|/pc)) that is positive toward the Galactic north pole. This finding underlines the important role of the dislocation of clusters in tracking the external environment of the Milky Way. The orientation (qpm) of the clusters, with epm ≥ 0.4, presents an aggregate distribution in the range of −45° to 45°, comprising about 74% of them. This probably suggests that these clusters tend to deform heavily in the direction of the Galactic plane. NGC 752 is in a slight stage of expansion in the two-dimensional space and will become deformed, in terms of its morphology, along the direction perpendicular to the original stretching direction in the future if no other events occur. The relative degree of deformation of the sample clusters in the short-axis direction decreases as their ages increase. On average, the severely distorted sample clusters in each group account for about 26% ± 9%. This possibly implies a uniform external environment in the range of |H| ≤ 300 pc if the sample completeness of each group is not taken into account.
A molecular wind blows out of the Kuiper belt
Authors: Kral Q. , Pringle J. E. , Guilbert-Lepoutre A. , Matrà L. , Moses J. I. , Lellouch E. , Wyatt M. C. , Biver N. , Bockelée-Morvan D. , Bonsor A. , Le Petit F. , Randall Gladstone G.
Published: September 2021

Context. In this Letter we aim to explore whether gas is also expected in the Kuiper belt (KB) in our Solar System.

Aims. To quantify the gas release in our Solar System, we use models for gas release that have been applied to extrasolar planetary systems as well as a physical model that accounts for gas released due to the progressive internal warming of large planetesimals.

Methods. We find that only bodies larger than about 4 km can still contain CO ice after 4.6 Gyr of evolution. This finding may provide a clue as to why Jupiter-family comets, thought to originate in the KB, are deficient in CO compared to Oort cloud comets. We predict that gas is still currently being produced in the KB at a rate of 2 × 10−8 M⊕ Myr−1 for CO and that this rate was orders of magnitude higher when the Sun was younger. Once released, the gas is quickly pushed out by the solar wind. Therefore, we predict a gas wind in our Solar System starting at the KB location and extending far beyond with regards to the heliosphere, with a current total CO mass of ∼2 × 10−12 M⊕ (i.e., 20 times the CO quantity that was lost by the Hale-Bopp comet during its 1997 passage) and CO density in the belt of 3 × 10−7 cm−3. We also predict the existence of a slightly more massive atomic gas wind made of carbon and oxygen (neutral and ionized), with a mass of ∼10−11 M⊕.

Results. We predict that gas is currently present in our Solar System beyond the KB and that, although it cannot be detected with current instrumentation, it could be observed in the future with an in situ mission using an instrument similar to Alice on New Horizons but with larger detectors. Our model of gas release due to slow heating may also work for exoplanetary systems and provide the first real physical mechanism for the gas observations. Lastly, our model shows that the amount of gas in the young Solar System should have been orders of magnitude greater and that it may have played an important role in, for example, planetary atmosphere formation.
Finite-time stabilization of an overhead crane with a flexible cable submitted to an affine tension
Authors: Wijnand Marc , d’Andréa-Novel Brigitte , Rosier Lionel
Published: September 2021

The paper is concerned with the finite-time stabilization of a coupled PDE–ODE system describing the motion of an overhead crane with a flexible cable. The dynamics of the flexible cable is described by the wave equation with a variable coefficient which is an affine function of the curvilinear abscissa along the cable. Using several changes of variables, a backstepping transformation, and a finite-time stable second-order ODE for the dynamics of a conveniently chosen variable, we prove that a global finite-time stabilization occurs for the full system constituted of the platform and the cable. The kernel equations and the finite-time stable ODE are numerically solved in order to compute the nonlinear feedback law, and numerical simulations validating our finite-time stabilization approach are presented.
Improving the stabilities of organic solar cells via employing a mixed cathode buffer layer
Authors: Guan Xi , Wang Yufei , Feng Shang , Zhang Jidong , Yang Qingqing , Liu Binyuan , Qin Dashan
Published: September 2021

Organic solar cells (OSCs) have been fabricated using cathode buffer layers based on bathocuproine (BCP) and 4,4'-N,N'-dicarbazole-biphenyl (CBP). It is found that despite nearly same power conversion efficiencies, the bilayer of BCP/CBP shows increased thermal stability of device than the monolayer of BCP, mostly because upper CBP thin film stabilizes under BCP thin film. The mixed layer of BCP:CBP gives slightly decreased efficiency than BCP and BCP/CBP, mostly because the electron mobility of the OSC using BCP:CBP is decreased than those using BCP and BCP/CBP. However, the BCP:CBP increases thermal stability of device than BCP and BCP/CBP, ascribed to that the BCP and CBP effectively inhibit reciprocal tendencies of crystallizations in the mixed layer. Moreover, the BCP:CBP improves the light stability of device than the BCP and BCP/CBP, because the energy transfer from BCP to CBP in in the mixed layer effectively decelerates the photodegradation of BCP. We provide a facial method to improve the stabilities of cathode buffer layers against heat and light, beneficial to the commercial development of OSCs.
Synthesis of Pentacoordinated Spiro[4.4]phosphoranes by Reaction of Cyclic Phosphazenyl Anions with Epoxides: Study of their P-Remote Functionalization and Hydrolysis
Authors: García López Jesús , López Ortiz Fernando , Sansores Peraza Pablo M. , Navarro Yolanda , Iglesias María J.
Published: September 2021

The synthesis of a new family of pentacoordinated spiro[4.4]phosphoranes stabilized by the ortho-benzamide bidentate ligand (oBA, -C6H4-2-C(O)NH-) through reaction of Cα,C
ortho
-dilithiated phosphazenes with oxiranes is reported. Mixtures of epimers that differ in configuration at the phosphorus atom were obtained with moderate to high yields and diastereoselectivities. C3-Disubstituted derivatives could be separated, which provided access to enantiopure products arising from the reaction with (R)-2-phenyloxirane. Stereomutation was observed by heating the spirophosphoranes at 100 °C. Directed ortho-lithiation of spirophoshoranes followed by electrophilic quench reactions including carbon-based and heteroatom-based electrophiles afforded derivatives functionalized in a remote position with respect to the phosphorus atom. Benzoic acid catalyzed hydrolysis of spirophosphoranes furnished ortho-(γ-hydroxyalkylphosphoryl)benzamides by cleavage of the P–O and P–N bonds with retention of the phosphorus configuration. In contrast, alkaline hydrolysis led to the formation of γ-hydroxyphosphinic acids and benzamide.
Nonthermal resection device for ablation of Barrett’s esophagus: a feasibility and safety study
Authors: Gotink Annieke W. , Peters Yonne , Bruno Marco J. , Siersema Peter D. , Koch Arjun D.
Published: September 2021

Background Several techniques exist for the eradication of Barrett’s esophagus (BE); however, all have limitations regarding successful conversion to squamous epithelium and a complication profile. We aimed to assess the feasibility and safety of a new nonthermal device, the EndoRotor, for the eradication of BE as a first-line ablation technique.

Methods Patients with BE were prospectively included at two tertiary referral centers in The Netherlands. Inclusion criteria: BE length 2–5 cm, with low grade dysplasia, high grade dysplasia, or residual BE after endoscopic resection (ER) of a lesion containing early neoplasia. Exclusion criteria: previous ER > 50 % circumference, or previous ablation therapy. Follow-up endoscopy was performed 3 months after ablation therapy. Outcomes were the percentage of endoscopically visible BE surface regression and complications.

Results 30 patients were included (age 66 years, interquartile range [IQR] 59–73, median BE C0M3, 25 male). Overall, 18 patients underwent ER prior to ablation. Median percentage BE ablated was 100 % (IQR 94 %–100 %). Median visual BE surface regression at 3-month follow-up was 80 % (IQR 68 %–95 %). Multiple residual Barrett’s islands were commonly seen. Six patients (20 %) had a treatment-related complication requiring intervention, including one perforation (3 %), one postprocedural hemorrhage (3 %), and four strictures (13 %). Post-procedural pain was reported in 18 patients (60 %).

Conclusions Endoscopic ablation of BE using this novel nonthermal device was found to be technically demanding, with a longer procedure time compared with established ablation techniques and a high complication rate. Based on these results, we do not recommend its use as a first-line ablation technique for the eradication of BE.
The German CArdioSurgEry Atrial Fibrillation Registry: In-Hospital Outcomes
Authors: Wehbe Mahmoud , Albert Marc , Lewalter Thorsten , Ouarrak Taoufik , Senges Jochen , Hanke Thorsten , Doll Nicolas ,   on behalf of the CASE-AF Investigators
Published: September 2021

Background The aim of this study was to describe outcomes of patients undergoing surgical ablation for atrial fibrillation (AF) as either stand-alone or concomitant cardiosurgical procedures in Germany.

Methods Patients with AF undergoing concomitant or stand-alone surgical ablation were included in the registry. Cardiac surgery centers across Germany were invited to participate and sought to enroll 1,000 consecutive patients. Data was obtained through electronic case report forms. The protocol mandated follow-up interviews at 1 year.

Results Between January 2017 and April 2020, 17 centers enrolled 1,000 consecutive patients. Among concomitant surgical patients (n = 899), paroxysmal AF was reported in 55.4% patients. Epicardial radio frequency (RF) bilateral pulmonary vein isolation (PVI) with excision of the left atrial appendage (LAA) was the most common operative strategy. In the stand-alone cohort (n = 101), persistent AF forms were reported in 84.1% of patients. Moderate-to-severe symptoms were reported in 85.1%. Sixty-seven patients had previously underwent at least two failed catheter ablative procedures. Thoracoscopic epicardial RF bilateral PVI and completion of a “box-lesion” with LAA closure were frequently preformed. Major cardiac and cerebrovascular complications occurred in 38 patients (4.3%) in the concomitant group. No deaths were reported in the stand-alone group. At discharge, sinus rhythm was achieved in 88.1% of stand-alone and 63.4% concomitant patients.

Conclusion The CArdioSurgEry Atrial Fibrillation registry provides insights into surgical strategies for AF ablation in a considerable cohort across Germany. This in-hospital data demonstrates that concomitant and stand-alone ablation during cardiac surgery is safe and effective with low complication rates.
Correction of Varus Alignment with Peripheral Osteophyte Removal during Total Knee Arthroplasty: An Assessment with Computer Navigation
Authors: Nishihara Nobuhiro , Masuda Hironari , Shimazaki Naoya , Toyooka Seikai , Kawano Hirotaka , Nakagawa Takumi
Published: September 2021

Techniques for symmetrical balancing in flexion and extension have been described; however, the ideal technique is unclear. This study aimed to clarify whether resection of peripheral osteophytes could restore neutral hip–knee–ankle (HKA) angle of varus deformity of arthritic knees. Data from 90 varus arthritic knees that had undergone total knee arthroplasty (TKA) using a nonimage-based navigation system were analyzed. The change in the coronal mechanical axis, while applying manual valgus stress at extension and 90 degrees of knee flexion, was recorded after the following sequential procedures: (1) anterior cruciate ligament (ACL) sectioning, (2) subperiosteal stripping of the deep medial collateral ligament (MCL) from the underlying osteophytes on the medial tibia, and (3) complete removal of peripheral osteophytes from the proximal medial tibia and distal medial femoral condyle. Repeated measures of analysis of variance (ANOVA) were performed to compare the varus angle among each step, and a post hoc analysis by paired t-test was utilized to compare the parameters between baseline and each step. The varus alignment with valgus stress at extension and 90 degrees of flexion (mean: 6.0 ± 3.6 and 5.2 ± 3.9 degrees of varus, respectively) was significantly corrected to a near-neutral mechanical axis (mean: 0.9 ± 2.4 and 1.4 ± 4.2 degrees of varus, respectively) after peripheral osteophyte resection (p < 0.01, both). In many cases, varus deformity of arthritic knees could be corrected to near-neutral HKA angle by applying manual valgus stress after complete peripheral osteophyte resection. These procedures could facilitate soft tissue balancing in TKA, minimizing the risk of overrelease of the medial soft tissues.
Anatomical Models versus Nontactile Distanced Learning in Otolaryngology Teaching
Authors: Pandya Aashish , Mistry Dylan , Owens David
Published: September 2021

Introduction Medical schools in the United Kingdom are under increasing pressure to provide more streamlined, applicable teaching due to rising numbers of trainee doctors but are failing to meet their educational need for otolaryngology. The recent novel coronavirus disease 2019 (COVID-19) pandemic has placed additional pressures on medical schools to adapt the medium over which the curriculum is delivered. The use of tactile learning with three-dimensional models and distanced learning via videoconferencing may provide alternative teaching methods to meet otolaryngology undergraduate learning requirements. This pilot study aimed to assess the differences in undergraduate student attitudes toward tactile learning via nontactile distanced learning and review their acceptability among this cohort.

Methods Two groups of medical students observed a single educational event on the larynx and management of the airway. The learning opportunity was delivered in a lecture format with the lecturer demonstrating on an anatomical model of the larynx. Group one (tactile group) had an identical model to interact with during the lecture and were present within the lecture theater; group two (nontactile group) did not and observed the lecture via video link. Students were asked to rank their opinion to several statements about the session based on an 11-point Likert's scale and give qualitative feedback.

Results All ranked feedback was mainly positive. Tactile learning was statistically equivalent to nontactile learning based on the ranked feedback from the students, except for “improvement in anatomical knowledge,” for which the students believed tactile learning was superior (p = 0.017). A variety of qualitative feedback was received by both groups.

Conclusion This pilot study provides evidence for the acceptability among students of the use of nontactile distanced learning to deliver the otolaryngology undergraduate curriculum compared with tactile learning. This can provide the basis for larger studies to assess the educational impact of these different teaching methods.
Association of Fluid Overload with Escalation of Respiratory Support and Endotracheal Intubation in Acute Bronchiolitis Patients
Authors: Baloglu Orkun , Flagg Lauren K. , Suleiman Ahmad , Gupta Vedant , Fast Jamie A. , Wang Lu , Worley Sarah , Agarwal Hemant S.
Published: September 2021

Fluid overload has been associated with increased oxygen requirement, prolonged duration of mechanical ventilation, and longer length of hospital stay in children hospitalized with pulmonary diseases. Critically ill infants with bronchiolitis admitted to the pediatric intensive care unit (PICU) also tend to develop fluid overload and there is limited information of its role on noninvasive respiratory support. Thus, our primary objective was to study the association of fluid overload in patients with bronchiolitis admitted to the PICU with respiratory support escalation (RSE) and need for endotracheal intubation (ETI). Infants ≤24 months of age with bronchiolitis and admitted to the PICU between 9/2009 and 6/2015 were retrospectively studied. Demographic variables, clinical characteristics including type of respiratory support and need for ETI were evaluated. Fluid overload as assessed by net fluid intake and output (net fluid balance), cumulative fluid balance (CFB) (mL/kg), and percentage fluid overload (FO%), was compared between patients requiring and not requiring RSE and among patients requiring ETI and not requiring ETI at 0 (PICU admission), 12, 24, 36, 48, 72, 96, and 120 hours. One-hundred sixty four of 283 patients with bronchiolitis admitted to the PICU qualified for our study. Thirty-four of 164 (21%) patients required escalation of respiratory support within 5 days of PICU admission and of these 34 patients, 11 patients required ETI. Univariate analysis by Kruskal-Wallis test of fluid overload as assessed by net fluid balance, CFB, and FO% between 34 patients requiring and 130 patients not requiring RSE and among 11 patients requiring ETI and 153 patients not requiring ETI, at 0, 12, 24, 36, 48, 72, 96 and 120 hours did not reveal any significant difference (p >0.05) at any time interval. Multivariable logistic regression analysis revealed higher PRISM score (odds ratio [OR]: 4.95, 95% confidence interval [95% CI]: 1.79–13.66; p = 0.002), longer hours on high flow nasal cannula (OR: 4.86, 95% CI: 1.68–14.03; p = 0.003) and longer hours on noninvasive ventilation (OR: 11.16, 95% CI: 3.36–36.98; p < 0.001) were associated with RSE. Fluid overload as assessed by net fluid balance, CFB, and FO% was not associated with RSE or need for ETI in critically ill bronchiolitis patients admitted to the PICU. Further prospective studies involving larger number of patients with bronchiolitis are needed to corroborate our findings.
Rainbows reflect structure and composition of graphene like samples
Authors: Patrick Chris
Published: September 2021

A morphological method developed to study the rainbow scattering of protons by graphene has applications beyond the end of the rainbow.
Preliminary Examination of Uncertainties due to Parton Distribution Functions in Far-Forward Neutrino Production at the Large Hadron Collider
Authors: Kumar Fnu Karan
Published: September 2021

A large flux of neutrinos is expected in the forward direction of the pp collisions [1, 3] at the Large Hadron Collider (LHC) at CERN. Several experiments have recently been proposed at CERN to detect these neutrinos and discussion has started on the possibility of building a Forward Physics Facility grouping many of them. Among the others, the FASER-nu [2] proposal consists of a lead + emulsion neutrino detector at a distance of 480 m from the ATLAS interaction region along the tangent to the LHC beamline. Old calculations of neutrinos rates in the forward direction were done to leading order in the QCD perturbative series. We have included next-to-leading order (NLO) terms in our calculation. We have also studied the effect of incorporating a non-perturbative Gaussian intrinsic kT. This kT effect mimics the contribution from missing higher-order terms in QCD calculations. We present the study of uncertainties due to scale variations and Parton Distribution Function (PDF) variations in the production rate of $D_s^ \pm$ and tau neutrinos in the far-forward Production at the Large Hadron Collider. We compare our predictions with the LHCb data with $D_s^ \pm$ production in the rapidity range of [2–4.5] at the LHC. In our studies, for which we consider various modern PDF sets, we also include the comparison of predictions obtained by different dynamical central scale assumptions.
Demonstrating the Sagnac Effect Using Tabletop Optics on a Rotary Platform
Authors: Mock Jonathan , Medlin Jared , Richards Matthew , Hamilton Edward
Published: September 2021

A Sagnac interferometer splits an incident beam of light into two components which travel in opposite directions of the same path. Consequently, each beam travels an equivalent distance. However, by rotating the entire apparatus at a sufficient speed, a noticeable change in the beams’ interference pattern is observed. This pattern results from one beam travelling against rotation and the other travelling with rotation, resulting in an increase or decrease in apparent path length, respectively. This is known as the Sagnac Effect. By using a traditional mirror-and-laser interferometer setup and a large turntable, we demonstrate the Sagnac Effect by showing that a given angular velocity results in a phase shift which matches what is predicted.
PhysiCL: An OpenCL-Accelerated Python Physics Simulator
Authors: Warner Benjamin
Published: September 2021

Numerical methods of physics analysis require specialized forms of programming as well as attention to issues of implementation. PhysiCL is a Python package that aims to provide general-purpose tools for performing OpenCL-accelerated physics simulations with ease. PhysiCL contains a Numpy-based code units system, a set of generic simulation tools, built-in tools for photon scattering, tools for measuring light behavior, and tools for writing new OpenCL-based simulation features. This package can be installed via PyPI using pip install physicl, and found on GitHub with source code and examples at https://github.com/bcwarner/physicl.
Viscoelastic Relaxation of the Nuclear Envelope Does Not Cause the Collapse of the Spindle After Ablation in S. pombe
Authors: Zareiesfandabadi Parsa , Elting Mary Williard
Published: September 2021

A large molecular machine called the mitotic spindle is responsible for accurate chromosome segregation in eukaryotic cells. The spindle consists of protein filaments known as microtubules and microtubule-associated proteins such as motors and crosslinkers, which help impart its organization. In the case of the fission yeast S. pombe, these form a single bundle inside the nucleus. During spindle elongation, sliding by motor proteins provides an internal source of extensile forces, which are resisted by the compressive forces of the nuclear envelope. To probe the sources of this force balance, we cut the spindle using focused laser light at various stages of spindle elongation. We find that the spindle pole bodies collapse toward each other post-ablation. While this basic behavior has been previously observed, many questions remain about the timing, mechanics, and molecular requirements of this phenomenon. Here, we quantify the time scale of the relaxation and probe its underlying mechanism. We demonstrate that viscoelastic relaxation of the nuclear envelope cannot explain this phenomenon and provide evidence of active forces as the underlying mechanism.
Characterization of nonlinear spin-wave interference by reservoir-computing metrics
Authors: Papp A. , Csaba G. , Porod W.
Published: September 2021

We study the computational potential of a spin-wave (SW) substrate by applying two metrics known from reservoir computing. At low intensities, SW scatterers can perform linear operations, while at higher intensities, nonlinear phenomena dominate, possibly enabling high-function, general-purpose computing. The transition between the linear and nonlinear regimes can be quantified by the intensity-dependent kernel rank (KR) and generalization rank (GR). The KR and GR metrics prove that the SW substrate displays the nonlinearities required for computing and give recipes for device designs that utilize nonlinearity.
Phase transition in piecewise linear random maps in the interval
Authors: Maldonado Cesar , Pérez Otero Ricardo A.
Published: September 2021

We consider a simple example of a one-parameter family of random maps in the interval that exhibits a phase transition phenomenon in the sense of a spontaneous transition from non-existence to existence of an absolutely continuous invariant measure by changing the parameter. For this example of random maps, we estimate numerically the critical value at which the so-called transition occurs. This is done through the numerical computation of its invariant densities and the Lyapunov exponent. We further investigate the behavior of the rate of decay of correlations for the different values of the parameter, changing from power-law-like to exponential-like behavior. We also study a family of random maps with a non-expansive branch having no phase transition. For this family of random maps, we compute the invariant densities for all values of the parameter.
Tubular phononic crystal sensor
Authors: Gueddida A. , Pennec Y. , Zhang V. , Lucklum F. , Vellekoop M. , Mukhin N. , Lucklum R. , Bonello B. , Djafari Rouhani B.
Published: September 2021

We propose the design of a tubular phononic crystal (TPC) for the purpose of sensing the physical properties of a liquid filling the hollow part of the tube. The TPC is constituted by a periodic repetition of washers along a hollow pipe with the advantage of avoiding any perturbation of a flowing fluid by any element inside the tube. Using finite element simulations, we demonstrate the existence of complete as well as polarization dependent bandgaps inside which one can design localized modes associated with defects. The most sensitive cavity to the liquid sound velocity is found to be constituted by a Fabry–Pérot (F–P) cavity. The signature of the cavity modes can be detected as peaks or dips in the transmission spectrum as well as at the external surface of the cavity. We study the dramatic effect of the liquid viscosity, more particularly shear viscosity, on these features and discuss the conditions for their practical observation. A TPC test sample made of a polymer is fabricated by means of 3D printing and characterized without the liquid by transmission measurements. The comparison with the simulations showed the necessity of considering the damping of the polymer whose effect on the transmission features is discussed. Our sensor design can find many applications at different scales in several systems transporting a fluid as microfluidic channels in micro- and nanotechnologies, syringes in medicine, or pipelines in civil engineering.
Initializing LSTM internal states via manifold learning
Authors: Kemeth Felix P. , Bertalan Tom , Evangelou Nikolaos , Cui Tianqi , Malani Saurabh , Kevrekidis Ioannis G.
Published: September 2021

We present an approach, based on learning an intrinsic data manifold, for the initialization of the internal state values of long short-term memory (LSTM) recurrent neural networks, ensuring consistency with the initial observed input data. Exploiting the generalized synchronization concept, we argue that the converged, “mature” internal states constitute a function on this learned manifold. The dimension of this manifold then dictates the length of observed input time series data required for consistent initialization. We illustrate our approach through a partially observed chemical model system, where initializing the internal LSTM states in this fashion yields visibly improved performance. Finally, we show that learning this data manifold enables the transformation of partially observed dynamics into fully observed ones, facilitating alternative identification paths for nonlinear dynamical systems.
Localized nodal solutions for semiclassical Choquard equations
Authors: He Rui , Liu Xiangqing
Published: September 2021

In this paper, we study the existence of localized nodal solutions for the semiclassical Choquard equation −ε2Δu+V(x)u=ε−α(Iα*|u|p)|u|p−2u for x∈RN. We establish for small ɛ the existence of a sequence of localized nodal solutions concentrating near a given local minimum point of the potential function V by using the perturbation method and the method of invariant sets of descending flow.
Comparison of strongly and weakly nonlinear flame models applied to thermoacoustic instability
Authors: Yang Lijun , Pang Bosheng , Li Jingxuan
Published: September 2021

Weakly nonlinear flame (or heater) dynamic models, only accounting for heat release rate disturbances from the flame (or heater) at forcing frequencies and omitting harmonic terms due to nonlinear mechanisms, are widely used in low-order tools for the analysis and prediction of thermoacoustic instabilities, because they have a numerical cost much cheaper than tools based on Navier–Stokes equations, and are easier to develop and validate. However, these models may lead to errors under certain conditions. The present work considers a Rijke tube model combustor, in which a classical third-order model is used to describe the flame dynamic response to the oncoming flow disturbance. We call this model the strongly nonlinear flame model. The weakly nonlinear flame model is then introduced. The wave-based approach is adopted as a low-order tool. The weakly and strongly nonlinear flame models are embedded in the low-order tool to reproduce the thermoacoustic instability of the model combustor. The natural frequency and growth rate of thermoacoustic instability are then determined by mode extracted methods. The differences between the results predicted by using the weakly and strongly nonlinear flame models are compared for a set of operating conditions, in order to find the conditions under which the weakly nonlinear flame model works. Short-time Fourier transform is adopted to analyze the extracted frequencies and growth rates of four selected cases. When the dominant acoustic mode strength is much stronger than the remaining modes, the weakly nonlinear models perform well. However, these models fail to capture the mode frequency and growth rate when multiple unstable modes are present.
Benchmarking an improved statistical adiabatic channel model for competing inelastic and reactive processes
Authors: Konings Maarten , Desrousseaux Benjamin , Lique François , Loreau Jérôme
Published: September 2021

Inelastic collisions and elementary chemical reactions proceeding through the formation and subsequent decay of an intermediate collision complex, with an associated deep well on the potential energy surface, pose a challenge for accurate fully quantum mechanical approaches, such as the close-coupling method. In this study, we report on the theoretical prediction of temperature-dependent state-to-state rate coefficients for these complex-mode processes, using a statistical quantum method. This statistical adiabatic channel model is benchmarked by a direct comparison using accurate rate coefficients from the literature for a number of systems (H2 + H+, HD + H+, SH+ + H, and CH+ + H) of interest in astrochemistry and astrophysics. For all of the systems considered, an error of less than factor 2 was found, at least for the dominant transitions and at low temperatures, which is sufficiently accurate for applications in the above mentioned disciplines.
Understanding improved photoelectrochemical performance in BaxSr1−xTiO3/TiO2 rod–shell nanostructures
Authors: Wang Wei , Weng Yuyan , Tu Baoxing , Zhou Yang , Zheng Fengang , Fang Liang , You Lu
Published: September 2021

Ferroelectric materials have been actively incorporated into photoelectrochemical (PEC) systems in recent years. The unscreened field induced by spontaneous polarization is believed to assist the charge separation and promote the solar energy conversion. However, the robustness of ferroelectricity in nanoscale heterostructures is plagued by detrimental size effects. Here, we report the unexpected improvement of PEC water splitting in BaxSr1−xTiO3/TiO2 rod–shell nanostructures with suppressed ferroelectric polarization. We propose that the enhanced electrical susceptibility due to ferroelectric instability facilitates the formation of ferroelectric polarons that protect the photocarrier transport from adverse recombinations with charged defects and opposite carriers, thus increasing the carrier lifetime and eventually boosting the cell efficiency. The results demonstrate the influence of dynamic polar order engineering on the photocarrier transport kinetics in ferroelectric-related PEC applications.
Dynamics of colloidal cubes and cuboids in cylindrical nanopores
Authors: Patti Alessandro , Cuetos Alejandro
Published: September 2021

Understanding how colloidal suspensions behave in confined environments has a striking relevance in practical applications. Despite the fact that the behavior of colloids in the bulk is key to identifying the main elements affecting their equilibrium and dynamics, it is only by studying their response under confinement that one can ponder the use of colloids in formulation technology. In particular, confining fluids of anisotropic particles in nanopores provides an opportunity to control their phase behavior and stabilize a spectrum of morphologies that cannot form in the bulk. By properly selecting the pore geometry, particle architecture, and system packing, it is possible to tune their thermodynamic, structural, and dynamical properties for ad hoc applications. In the present contribution, we report Grand Canonical and Dynamic Monte Carlo simulations of suspensions of colloidal cubes and cuboids constrained into cylindrical nanopores of different sizes. We first study their phase behavior, calculate the chemical potential vs density equation of state, and characterize the effect of pore walls on particle anchoring and layering. In particular, at large enough concentrations, we observe the formation of concentric nematic-like coronas of oblate or prolate particles surrounding an isotropic core, whose features resemble those typically detected in the bulk. We then analyze the main characteristics of their dynamics and discover that these are dramatically determined by the ability of particles to diffuse in the longitudinal and radial directions of the nanopore.
Characteristics of shock tube generated compressible vortex rings at very high shock Mach numbers
Authors: Poudel Sajag , Chandrala Lakshmana , Das Debopam , De Ashoke
Published: September 2021

Compressible vortex rings are usually formed at the open end of a shock tube. They show exciting flow phenomena during their formation, evolution, and propagation depending on the shock Mach number (Ms) and exit flow conditions. This study considers high shock tube pressure ratio (PR) cases showing hitherto unknown, spectacular flow structures. With hydrogen as a driver section gas at high PR, a supersonic compressible vortex ring having vortex ring Mach number (Mv) >1 is obtained for the first time. The formation of multiple triple points and the corresponding slipstream shear layers and, thus, multiple counter-rotating vortex rings (CRVRs) behind the primary vortex ring at different radial locations, in addition to the usual CRVRs, appears to be a unique characteristic for high Mach number vortex rings. During the formation stage, a vortex layer of reverse circulation than that of the primary vortex ring gets generated from the outer wall of the shock tube. The instability of such a vortex layer creates another series of opposite circulation vortices, which later interfere with the primary vortex core considerably. Also, a near stationary slipstream vortex and multiple fast-moving tiny vortices of opposite circulation to the slipstream vortex are observed near the central zone. Mechanisms for the formation of these complex vortical structures are identified. The implications of these phenomena on the vortex ring's geometric and kinematic characteristics, such as ring diameter, core diameter, circulation, and translational velocity, are discussed in detail, illustrating their differences with low vortex ring Mach number cases considering 0.31 < Mv < 1.08.
An accurate moving wall boundary algorithm for direct simulation of Monte Carlo in unsteady rarefied flow
Authors: Zhang He , Shan Fanli , Fang Hong , Zhang Xing , Zhang Jun , Sun Jinghua
Published: September 2021

An accurate algorithm is proposed to improve the prediction of a particle in collision with a moving wall within the direct simulation Monte Carlo framework for the simulation of unsteady rarefied flows. This algorithm is able to predict the particle-wall collision in a coupled manner by removing the assumption employed by the approximate algorithm, in that the wall is frozen during the collision. The trajectory equation of the particle is theoretically constructed in a moving object coordinate system. It can accurately describe the geometries of the collision between a particle and an arbitrary shaped object of which the motion incorporates both translation and rotation, thus allowing to deal with complex problems. In contrast, the approximate algorithm ignores the effect of the moving wall on the particle movement during the collision and therefore induces error that is an increasing function of the wall velocity. Four rarefied flow problems are applied to validate the accurate algorithm. It is shown that the algorithm can produce results perfectly consistent with the Maxwellian theoretical solutions and ensure particle conservation to avoid gas leakage. It is also shown in a three-dimensional case of a re-entry module that the steady simulation fails to reproduce the hysteresis effect while the unsteady simulation using the accurate algorithm can do that, indicating that the unsteady simulation with an appropriate algorithm as proposed in the present work is essentially required in such applications.
Enhancing the self-reconstruction ability of the degree of coherence of a light beam via manipulating the cross-phase structure
Authors: Pan Ruixuan , Liu Xin , Tang Jiahui , Ye Hao , Liu Zhenzhen , Ma Pujuan , Wen Wei , Hoenders Bernhard J. , Cai Yangjian , Liang Chunhao
Published: September 2021

The degree of coherence function of a light beam could be used for optical encryption, robust optical imaging, and other purposes. However, recent works demonstrated that it has a puny self-reconstruction ability that gets worse as the obstacle is further away from the source. In this manuscript, we propose a method by which, with the help of only the introduction of a cross-phase structure in the degree of coherence function, the self-reconstruction ability of the degree of coherence function could be significantly enhanced. The performance of the method is independent of the location of the obstacle. The results, achieved in this manuscript, will shed new light on optical imaging, optical encryption, and optical communication in a complex environment.
Research on thermal properties of flexible electronic devices under solar radiation
Authors: Wang Bo , Sun Chen , Chen Jubing
Published: September 2021

Flexible electronic technology is now widely developed in wearable products for humans and the detection of physiological characteristics, track tracking, and analysis of the living environment for animals and plants. In these application scenarios, flexible electronic devices (FEDs) may work outdoors for a long time and may be exposed to strong solar radiation, which may cause the temperature of FEDs to be too high and affect their stability. Hence, a quantitative description of the thermal properties of FEDs is helpful to provide a reference for the design of related FEDs. This paper establishes a three-dimensional thermal analysis model, verified by the finite element method and experiments, to analyze the temperature increase in the interface of the device under solar radiation and generated by the device itself, and analyzes the parameters that have an influence on the temperature increase in the interface, including the thickness of the substrate and the encapsulated layer and the power of the device. On this basis, the contributions for these parameters to the temperature increase in the interface are further compared.
NAD
+
supplementation reduces neuroinflammation and cell senescence in a transgenic mouse model of Alzheimer’s disease via cGAS–STING
Authors: Hou Yujun , Wei Yong , Lautrup Sofie , Yang Beimeng , Wang Yue , Cordonnier Stephanie , Mattson Mark P. , Croteau Deborah L. , Bohr Vilhelm A.
Published: September 2021

Significance

Impaired neuronal bioenergetics and neuroinflammation are thought to play key roles in the progression of Alzheimer's disease (AD), but their interplay is not clear. AD mouse brains showed lower nicotinamide adenine dinucleotide (NAD
+
) levels and alterations in inflammation. Treatment of AD mice with NR reduced neuroinflammation, attenuated DNA damage, and prevented cellular senescence. We present evidence that the beneficial effects of nicotinamide riboside (NR) are, in part, through a cyclic GMP-AMP synthase (cGAS)–stimulator of interferon genes (STING)-dependent pathway. DNA damage was increased in AD and attenuated by NR. Both cGAS–STING and NAD
+
pathways are potential therapeutic targets for AD.
Tetraspanin 6 is a regulator of carcinogenesis in colorectal cancer
Authors: Andrijes Regina , Hejmadi Rahul K. , Pugh Matthew , Rajesh Sundaresan , Novitskaya Vera , Ibrahim Maha , Overduin Michael , Tselepis Chris , Middleton Gary W. , Győrffy Balázs , Beggs Andrew D. , Berditchevski Fedor
Published: September 2021

Significance

Tetraspanin protein (Tspan6) is a member of the tetraspanin family. Using a combination of in vitro and in vivo assays, we demonstrate that Tspan6 functions as a tumor suppressor in colorectal cancer (CRC) by attenuating the epidermal growth factor receptor (EGFR)–based signaling axis. Tspan6 forms a tripartite complex with transmembrane form of TGF-α and an adaptor protein syntenin-1 and negatively regulates secretion of TGF-α. The expression of Tspan6 is frequently decreased in CRC, and this correlates with poor survival. Importantly, the expression of Tspan6 in CRC correlated independently of tumor molecular profile with better patient responses to Cetuximab, an EGFR-targeted therapy. These results identify Tspan6 as a regulator of CRC development and a potential predictive biomarker for EGFR-targeted therapies.
Massive and rapid predominantly volcanic CO
2
emission during the end-Permian mass extinction
Authors: Cui Ying , Li Mingsong , van Soelen Elsbeth E. , Peterse Francien , Kürschner Wolfram M.
Published: September 2021

Significance

The end-Permian mass extinction event (ca. 252 Mya) is the most-severe biodiversity loss in Earth’s history and is globally recognized by a rapid negative carbon isotope excursion. The trigger of this event, however, remains controversial. New paired terrestrial and marine compound-specific carbon isotope records may provide clues for this enigma. By comparing observed data to results from an isotope-enabled Earth system model, we find that a massive and rapid, predominantly volcanic CO
2
emission during the Siberian Traps volcanism is likely the trigger for the carbon isotope excursion and the severe mass extinction. Our findings provide quantitative constraints of how a massive and rapid increase in CO
2
may have influenced the marine ecosystem 252 Mya.
The endogenous circadian system worsens asthma at night independent of sleep and other daily behavioral or environmental cycles
Authors: Scheer Frank A. J. L. , Hilton Michael F. , Evoniuk Heather L. , Shiels Sally A. , Malhotra Atul , Sugarbaker Rena , Ayers R. Timothy , Israel Elliot , Massaro Anthony F. , Shea Steven A.
Published: September 2021

Significance

For centuries, it has been recognized that asthma severity shows a daily rhythm, with the worst symptoms at night. However, it is unclear to what degree this is driven by everyday behaviors, such as sleep, physical activity, and body posture changes, versus intrinsic rhythms generated by the internal body clock (i.e., the circadian system). To distinguish the contribution of the circadian system, patients with asthma underwent two complementary gold-standard circadian protocols: a constant routine and a forced desynchrony protocol. These highly standardized protocols revealed that the endogenous circadian system plays a significant role in modulating pulmonary function and asthma severity independent of sleep and other daily behavioral or environmental cycles. Moreover, these circadian influences summate with daily behavioral and environmental effects to drive asthma to be worst at night.
The adaptive challenge of extreme conditions shapes evolutionary diversity of plant assemblages at continental scales
Authors: Neves Danilo M. , Kerkhoff Andrew J. , Echeverría-Londoño Susy , Merow Cory , Morueta-Holme Naia , Peet Robert K. , Sandel Brody , Svenning Jens-Christian , Wiser Susan K. , Enquist Brian J.
Published: September 2021

Significance

We explore an extended view of the tropical conservatism hypothesis to account for two often-neglected components of climatic stress: drought and the combined effect of seasonal cold and drought—the latter being a common feature of extratropical dry environments. We show that evolutionary diversity of angiosperm assemblages in extratropical dry biomes is even lower than in biomes subject to only one type of climatic stress. We further show that evolutionary diversity in many assemblages from eastern North America is higher or comparable to that of tropical moist forests, suggesting that some extratropical moist biomes have accumulated angiosperm lineages over deep evolutionary timescales with their flora assembled from lineages that represent the entirety of the angiosperm tree of life.