bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow morphology in bottom-propagating gravity currents over immersed obstacles
Authors: Wu Ching-Sen , Ouyang Huei-Tau
Published: November 2020

The interaction of bottom-propagating gravity currents with immersed obstacles in the path of the lock-exchange configuration was numerically investigated based on large eddy simulations. The three-dimensional Navier–Stokes solver was quantitatively employed to resolve the flow structure of gravity currents and their dynamics during impact. The integral measure of analysis comprises the front condition, the energy budget, the turbulent mixing, and the force response. Some flow parameters involved in momentum and energy fluctuations are the fractional depth of volume release, relative density difference, and obstacle dimensions. A particular focus in this study was on the scale effect of obstacles (W/D, the aspect ratio of a cross-sectional obstacle with side length W to height D) that affect the propagation of gravity currents. Depending on integral measures of the simulation, the flow morphology could be demarcated for the condition W/D = 2 with different flow regimes in accordance with the reattachment of the current as the plunged front overflows and separates from the obstacle. For W/D > 2, as the current impinges on the obstacle, the plunged current front overtops and travels on the obstacle surface and consequently causes the entrainment without intense mixing to form a circulation zone at the downstream of the obstacle. Accordingly, the predicted drag forces acting on the downstream surface are reduced by ∼25% for W/D ≥ 4 comparing to the case of W/D = 0.5, which is beneficial to the structural stability of the barrier in practical aspect. Notably, the integrated analysis of gravity currents provides insights into physical mechanisms by identifying distinct propagation stages during transitions, including the impact stage, transient stage, and quasi-steady stage.
Effect of particle size distribution on polydisperse hard disks
Authors: Sampedro Ruiz Pablo , Ni Ran
Published: November 2020

Using Monte Carlo simulations, we systematically investigate the effect of particle size distribution on the phase behavior of polydisperse hard disks. Compared with the commonly used Gaussian-like polydisperse hard disks [P. Sampedro Ruiz, Q.-l. Lei, and R. Ni, Commun. Phys. 2, 70 (2019)], we find that the phase behavior of polydisperse hard-disk systems with lognormal and triangle distributions is significantly different. In polydisperse hard-disk systems of lognormal distributions, although the phase diagram appears similar to that of Gaussian-like polydisperse hard disks, the re-entrant melting of the hexatic or solid phase cannot be observed in sedimentation experiments. For polydisperse hard-disk systems of triangle distributions, the phase behavior is qualitatively different from the Gaussian-like and lognormal distributions, and we cannot reach any system of true polydispersity larger than 0.06, which is due to the special shape of the triangle distribution. Our results suggest that the exact particle size distribution is of primary importance in determining the phase behavior of polydisperse hard disks, and we do not have a universal phase diagram for different polydisperse hard-disk systems.
Theoretical analysis for dynamic contact angle hysteresis on chemically patterned surfaces
Authors: Xu Xianmin , Wang Xiaoping
Published: November 2020

A dynamic wetting problem is studied for a moving thin fiber inserted in fluid and with a chemically inhomogeneous surface. A reduced model is derived for contact angle hysteresis by using the Onsager principle as an approximation tool. The model is simple and captures the essential dynamics of the contact angle. From this model, we derive an upper bound of the advancing contact angle and a lower bound of the receding angle, which are verified by numerical simulations. The results are consistent with the quasi-static results. The model can also be used to understand the asymmetric dependence of the advancing and receding contact angles on the fiber velocity, which was observed recently in the physical experiments reported in the work of Guan et al. [“Asymmetric and speed-dependent capillary force hysteresis and relaxation of a suddenly stopped moving contact line,” Phys. Rev. Lett. 116, 066102 (2016)].
Ti3C2Tx MXene for wearable energy devices: Supercapacitors and triboelectric nanogenerators
Authors: Nam Sanghee , Kim Jong-Nam , Oh Saewoong , Kim Jaehwan , Ahn Chi Won , Oh Il-Kwon
Published: November 2020

A family of two-dimensional (2D) transition metal carbides and/or nitrides, the so-called MXenes, has been discovered and investigated for advanced energy devices with outstanding performances. The outstanding physical and chemical properties of MXenes with 2D layered structures, high mechanical strength, metallic electrical conductivity, sufficient surface functional groups, hydrophilic nature, high negative zeta-potential, high surface area, large potential charge capability, and ability to accommodate intercalants are attractive for engineering applications to energy devices, particularly in wearable supercapacitors and triboelectric nanogenerators. This research update provides an overview of practical challenges and recent advances of synthetic routes and a perspective on applications to wearable energy storage and energy harvesting devices.
Generalized synchronization on the onset of auxiliary system approach
Authors: Rakshit Sarbendu , Ghosh Dibakar
Published: November 2020

Generalized synchronization is an emergent functional relationship between the states of the interacting dynamical systems. To analyze the stability of a generalized synchronization state, the auxiliary system technique is a seminal approach that is broadly used nowadays. However, a few controversies have recently arisen concerning the applicability of this method. In this study, we systematically analyze the applicability of the auxiliary system approach for various coupling configurations. We analytically derive the auxiliary system approach for a drive–response coupling configuration from the definition of the generalized synchronization state. Numerically, we show that this technique is not always applicable for two bidirectionally coupled systems. Finally, we analytically derive the inapplicability of this approach for the network of coupled oscillators and also numerically verify it with an appropriate example.
Investigation into quasi-static and dynamic tensile mechanical properties of aluminium–scandium alloy
Authors: Lin Chi-Feng , Chen Tao-Hsing , Tsai Liren , Hsieh Tsung-Han , Su Wei-Chih , Wang I.-Hsin
Published: November 2020

The mechanical properties of aluminium–scandium alloy are investigated at strain rates ranging from 0.0005 to 2600 s−1 and a temperature of 25°C using a material testing system and split-Hopkinson tensile bar. The temperature dependence of the material response is investigated at elevated temperatures of 100 to 300°C under a strain rate of 0.0005 s−1. The flow stress increases with increasing strain rate but decreases with increasing temperature. The scanning electron microscope observations reveal that the fracture surface contains a large number of dimpled structures with intermetallic precipitates, which suggests a ductile failure mode. Material constants for a combined Johnson-Cook/Cowper-Symonds constitutive model are determined to describe the dynamic behaviours of aluminium–scandium alloys.
Effect of crystal orientation on the size effects of nano-scale fcc metals
Authors: Bagheripoor Mahdi , Klassen Robert
Published: November 2020

The present work investigates the dominant mechanisms in the plasticity of nano-sized fcc metallic samples. Molecular dynamics simulations of nanopillar compression show that plasticity always starts with the nucleation of dislocations at the free surface, and the crystal orientation affects the subsequent microstructural evolution. The Schmid factor of leading and trailing partials plays a decisive role in leading to the twinning, or slip deformation. A significant difference is observed in the strength of pillars of the same size with different orientations. The power-law equation exponent is completely dependent on the crystal orientations, and a weak or no size effect is observed in the compression of [100]- and [110]-oriented nanopillars. The observed orientation based behaviour decreases by confining the free surface.
Mechanical alloying and spark plasma sintering of AlCrCuFeZn high entropy alloy
Authors: Cardoso Kátia Regina , da Silva Izaias Bruno , de Souzade Souza Vieira Leonardo , Bepe André Mello
Published: November 2020

The AlCrCuFeZn multi-component high entropy alloy was synthesised by mechanical alloying and spark plasma sintering (SPS). Alloying behaviour, microstructure and phase stability were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). In the metastable as-milled condition, two disordered body centred cubic (BCC) phases were observed with crystallite size less than 40 nm. SPS was efficient in obtaining high densification, 91%, in the sintered condition. The structural evolution during the sintering occurred by the formation of two stable phases, one enriched in CuZn with Cu5Zn8-type structure, and another enriched in FeAlCr with a BCC structure. High hardness of 661 and 627 HV was obtained in the as-milled powder and SPS sintered sample, respectively.
X-ray of Spanish universities: management, structure, educational programmes and budgets (Radiografía de las universidades españolas: gestión, estructura, programas formativos y presupuestos)
Authors: Sierra-Sánchez Javier , Sotelo-González Joaquín , Vivar-Zurita Hipólito
Published: November 2020

This empirical study analyses the current status of Spanish universities from three vantage points: legal, economic and academic management. We use the content analysis technique to analyse all the universities that belong to CRUE ( Conferencia de Rectors de las Universidades Españolas / Conference of Rectors of Spanish Universities) from these three vantage points in order to inquire into some of the structural variables that affect the way these universities operate: people (rectors), programmes (contents) and budgets (economics and financing). The study finds that the leaders of Spanish universities are primarily men educated in the sciences and health sciences, and that there is notable margin for improvement in the Spanish university governance system.
Early functional treatment or trivialization? – current treatment strategies in lateral ligament injuries of the ankle
Authors: Popp Daniel , Weber Johannes , Kerschbaum Maximilian , Schicho Andreas , Baumann Florian , Hilber Franz , Krutsch Werner , Alt Volker , Pfeifer Christian
Published: November 2020

Introduction: Ankle injuries are common in daily orthopaedic trauma practice, with a high incidence of lateral ligament complex (lat‐lig‐com) injuries of the ankle joint (AJ). Primarily, these lat‐lig‐com injuries heal sufficiently, although there is a risk of developing chronic ankle instability. However, there is a lack of knowledge about the clinical application and routine for rehabilitation strategies so as to prevent chronic instability. This study investigates the current rehabilitation concepts in clinical routine after ligament injuries of the AJ. Methods: Rehabilitation protocols, provided by orthopaedic and trauma surgery institutions in German speaking countries, were analysed in terms of weight‐bearing, range of motion (ROM), physiotherapy and choice of orthosis. All protocols for operatively and non‐operatively (nop) treated ligament ruptures of the AJ were included. Results: 120 of 213 institutions provided protocols of lat‐lig‐com injuries of the AJ. Regarding the orthosis, the nop‐treatment group mainly used ankle braces; in contrast, the operative group preferred the use of an ankle boot. The operative group recommends 6–12 weeks for duration of orthosis in contrast to only 6 weeks in the nop group. Significant differences prevail in ROM, with free ROM in non‐operative treatment from the first day after trauma (p<0.001) in contrast to a careful increase in ROM in the first 6 weeks post‐operatively. Conclusion: Early functional treatment is clinical standard in rehabilitation after lat‐lig‐com injuries of the ankle. Regarding current literature the differences of restrictions in ROM and orthosis treatment after lat‐lig‐com injuries suggest a trivialization of conservative treatment in the first period after trauma compared to post‐operative aftercare.
An exactly solvable toy model
Authors: Wang X G , Zhang J M
Published: November 2020

In an attempt to regularize a previously known exactly solvable model (Yang and Zhang 2019 Eur. J. Phys.
40 035401), we find yet another exactly solvable toy model. The interesting point is that while the Hamiltonian of the model is parameterized by a function f(x) defined on [0, ∞), its spectrum depends only on the end values of f, i.e., f(0) and f(∞). This model can serve as a good exercise in quantum mechanics at the undergraduate level.
Nitrogen-doped carbon-coated nanodiamonds for electrocatalytic applications
Authors: Hung Tran Van , Karunagaran Ramesh , Tung Tran Thanh , Dang Nam Nguyen , Nguyen Sang Xuan , Losic Dusan
Published: November 2020

Nitrogen-doped carbon hybridized nanodiamond (N-doped C@ND) materials have been developed and used as an electrocatalytic for oxygen reduction reactions (ORRs). The polymerized ionic liquids are employed to modify NDs and then subjected to thermal annealing at 600 °C, resulting in a high concentration of N-doped (9.33 at.%) carbon frameworks attached on the ND surface. This N-doped C@ND material provides a highly active mesoporous structure (4 nm pore) with a high surface area (366 m2 g−1) and allows for enhancement of catalytic performance compared to pure NDs. The N-doped C layers altered the electroneutrality of NDs, creating favourable charged sites for oxygen adsorption, thus weakening the O–O bond strength to facilitate ORR activity. Having a predominant four-electron transfer pathway with a total electron transfer number of 3.44–3.88 in the potential region of 0.1–0.8 VRHF, the N-doped C@ND-based catalyst materials performed well as a catalyst for the ORR in the alkaline medium. This affordable material and simple process will find potential application in clean energy generation and storage, durable fuel cells and metal–air batteries.
Enhanced broadband acoustic sensing in gradient coiled metamaterials
Authors: Chen Tinggui , Jiao Junrui , Yu Dejie
Published: November 2020

Enhanced acoustic sensing is a topic of interest in a variety of research fields. Here, we propose a gradient coiling up metamaterial (GCM), combining gradient and coiled structures, so as to realize enhanced broadband acoustic sensing. Compared with metamaterials without coiled structures, the GCM shows a far superior performance in terms of acoustic enhancement, enabling the acoustic signals to be magnified up to approximately 80 times, over a wide frequency range. Moreover, by virtue of coupling the coiled structures, trapped and enhanced frequencies in the GCM can be reduced by nearly 43%. In addition, we numerically and experimentally demonstrate the property of frequency-selective enhancement over a wide frequency range, which can be used to approximate unknown signals by changing their measured positions. Moreover, harmonic signals with useful information can be effectively recognized and recovered from strong background noise, using GCM. Our results indicate that GCMs can be regarded as a functional material or an enhanced acoustic sensing device to improve the acoustic sensing performance of signal detection in practical engineering applications.
Breaking μ − τ symmetry of tri-bimaximal mixing
Authors: Channey Kanwaljeet S , Kumar Sanjeev
Published: November 2020

The TBM neutrino mass matrix is invariant under the TM1, TM2, and μ − τ exchange symmetry. The prediction of vanishing θ
13 by TBM is due to its invariance under μ − τ exchange symmetry. We can construct neutrino mass textures where TBM mass matrix is the main contributing matrix and a μ − τ symmetry breaking term is added as an additional contribution. The overall matrix will be invariant under either TM1 or TM2 symmetry only. We present eight such textures which are invariant under either TM1 or TM2 symmetry but are not invariant under the μ − τ exchange symmetry. These textures give definite predictions on the values of m

β
, m

ββ
, CP violating phase δ, and the octant of the mixing angle θ
23.
LiDAR point’s elliptical error model and laser positioning for autonomous vehicles
Authors: Liu Xiangyong , Sun Xuesong , Xia Xin
Published: November 2020

Automated driving is the development trend of vehicle driving, and laser LiDAR is the high-precision positioning sensor that automated driving relies on most. Laser positioning mainly depends on the relative orientation from the detected environment features to the self-vehicle. However, when there are multiple detected features that carry different orientation information, all the data are redundant. In order to improve the vehicle’s positioning accuracy, two laser point evaluation models were put forward. First, based on the plane area analysis method, a spot error model was proposed, and the error distribution with the incidence angle and scanning distance was obtained. Second, the laser point’s position approximately obeys the Gaussian distribution, the laser’s stereo error ellipsoid model was established, and the laser point’s probability volume was calculated through the probability integration. Third, the point cloud features were extracted by a proposed roughness method, the point accuracy was evaluated by the proposed spot and stereo error models, and the points’ relative weights were recalculated in the laser signal’s positioning process. Finally, in order to verify the laser point’s evaluation positioning method, the simulation and experimental verifications were conducted. The results show that the evaluation method based on the error ellipse models can improve the laser positioning accuracy effectively.
Atomistic simulations of gold surface functionalization for nanoscale biosensors applications
Authors: Dutta Sutapa , Bellucci Luca , Agostini Matteo , Gagliardi Mariacristina , Corni Stefano , Cecchini Marco , Brancolini Giorgia
Published: November 2020

A wide class of biosensors can be built via functionalization of gold surface with proper bio conjugation element capable of interacting with the analyte in solution, and the detection can be performed either optically, mechanically or electrically. Any change in physico-chemical environment or any slight variation in mass localization near the surface of the sensor can cause differences in nature of the transduction mechanism. The optimization of such sensors may require multiple experiments to determine suitable experimental conditions for the immobilization and detection of the analyte. Here, we employ molecular modeling techniques to assist the optimization of a gold-surface biosensor. The gold surface of a quartz-crystal-microbalance sensor is functionalized using polymeric chains of poly(ethylene glycol) (PEG) of 2 KDa molecular weight, which is an inert long chain amphiphilic molecule, supporting biotin molecules (bPEG) as the ligand molecules for streptavidin analyte. The PEG linkers are immobilized onto the gold surface through sulphur chemistry. Four gold surfaces with different PEG linker density and different biotinylation ratio between bPEG and PEG, are investigated by means of state-of-the art atomistic simulations and compared with available experimental data. Results suggest that the amount of biotin molecules accessible for the binding with the protein increases upon increasing the linkers density. At the high density a 1:1 ratio of bPEG/PEG can further improve the accessibility of the biotin ligand due to a strong repulsion between linker chains and different degree of hydrophobicity between bPEG and PEG linkers. The study provides a computaional protocol to model sensors at the level of single molecular interactions, and for optimizing the physical properties of surface conjugated ligand which is crucial to enhance output of the sensor.
Expansion of alternatively extracted ion–ion beam in a low pressure collisional medium
Authors: Oudini N , Bendib A
Published: November 2020

The aim of this paper is to investigate, through particle-in-cell with Monte Carlo collisions (PIC-MCC) simulations, the effects of collisions on the expansion of an ion–ion beam formed by the alternate extraction of oppositely charged ions. This beam is extracted from an ion–ion plasma, formed in the downstream of a radiofrequency magnetically filtered iodine electronegative plasma, by the mean of two extraction grids. In this grid system, the screen grid is biased with a square voltage waveform, in the low MHz range, while the acceleration grid is grounded. The collisionless interaction between the extracted ion packets involves and enhances electrostatic waves propagating at beam velocity. Our results show that in addition to these electrostatic waves, the presence of significant fraction of low energy ions, produced by charge exchange, beside extracted fast ions gives rise to two-stream instability. Furthermore, space and time dependent electric field might accelerate the slow ions, produced by charge exchange collision. This acceleration, involving Landau damping and its inverse mechanism, is mainly due to the interaction between ions and potential patterns inherent to two-stream instability.
Suppression of nonlinear standing wave excitation via the electrical asymmetry effect
Authors: Zhao Kai , Su Zi-Xuan , Liu Jia-Rui , Liu Yong-Xin , Zhang Yu-Ru , Schulze Julian , Song Yuan-Hong , Wang You-Nian
Published: November 2020

The electrical asymmetry effect (EAE) enables separate control of the ion flux and the mean ion energy in capacitively coupled plasmas (CCP). While a variety of plasma processing applications benefit from this, large-area, very-high-frequency CCPs still suffer from lateral nonuniformities caused by electromagnetic standing wave effects (SWE). Many of such plasma sources are geometrically asymmetric and are operated at low pressure so that high frequency nonlinear plasma series resonance (PSR) oscillations of the RF current are self-excited. These PSR oscillations lead to the presence of short wavelength electromagnetic waves and a more pronounced SWE. In this work, we investigate the influence of the EAE on the nonlinear standing wave excitation in a geometrically asymmetric, low pressure capacitively coupled argon plasma driven by two consecutive harmonics (30 MHz and 60 MHz) with an adjustable phase shift, θ. We use a hairpin probe to determine the radial distribution of the electron density in combination with a high-frequency B-dot probe to measure the radial distribution of the harmonic magnetic field, which in turn is used to calculate the harmonic current density based on Ampere’s law. Our experimental results show that the asymmetry of the discharge can be reduced electrically via the EAE. In this way the self-excitation of high frequency PSR oscillations can be attenuated. By tuning θ, it is, therefore, possible to switch on and off the nonlinear standing wave excitation caused by the PSR and, accordingly, the plasma uniformity can be optimized.
Finite strain elasticity based cohesive zone model for mechanoluminescent composite interface: I. Stiffness of the undamaged interface
Authors: Krishnan S , Katsube N , Sundaresan V
Published: November 2020

Light emission from inorganic crystals due to elastic loading, termed piezoluminescence or EML, is of great practical interest due to repeatability of emission. Two architectures demonstrated for utilization of EML are thin films and particulate composites, with the majority of recent literature focusing on the latter. Specifically, EML of doped zinc sulfide phosphor particles dispersed in polymer matrices has been recently demonstrated for a growing number of applications. This necessitates the need to understand the micromechanics of stress transfer within these composites for building accurate EML models as well as fatigue models to predict functional life estimates of the EML devices. Macroscale stress measurements can be combined with material properties through micromechanical models to estimate stress transfer to the particulate phase. Apart from the material properties of the matrix and particles, the bonding between the two phases also influences stress transfer significantly. The bonding at the interface is modeled through a CZM which provides a deterministic way to track interfacial damage due to fatigue. A bilinear CZM defines the undamaged stiffness of the interface (

k
σ

i
n
t

)

and its resistance to damage (

k
˜

σ

i
n
t

)

in two piecewise linear stages. In this paper, we utilize established micromechanical models to determine the stiffness of the undamaged interface

k
σ

i
n
t

between EML ZnS:Cu particles and PDMS matrix in the normal and tangential directions (

k
σ
n

and

k
σ
t

) with the help of experimentally determined mechanical and morphological properties of EML–PDMS composites.

k
σ
n

and

k
σ
t

determined are then validated by comparing stress strain behavior of a finite element representative volume with experimental monotonic tensile test results to find good correlation.
Finite strain elasticity based cohesive zone model for mechanoluminescent composite interface: Part II. Interface damage characteristics
Authors: Krishnan S , Katsube N , Sundaresan V
Published: November 2020

The need to estimate the micromechanical properties of elastico-mechanoluminescent (EML) composites was established in Part A of this paper. The particle–matrix interface was identified to be poorly understood towards building accurate EML models and to predict functional life estimates of the EML devices. Towards this, Part A of this paper defined the mechanical behavior of the interface as a softening spring through a bilinear cohesive zone model (CZM). Macroscale stress measurements were combined with material properties to estimate undamaged stiffness of the interface spring (

k
σ

i
n
t

). In Part B of this paper, the damage characteristics of the interface spring are estimated through an experimental approach to complete the CZM. This is achieved by first establishing the finite strain behavior of the macroscopic EML–PDMS composite from uniaxial tensile testing. Secondly, a controlled tear is induced in the composite and the microscale displacement fields around the tear tip are captured using digital image correlation technique. Tear tip displacements and finite strain behavior are combined to estimate cohesive stresses in the tear-tip region of the composite. The contribution of particle–matrix interfaces towards resisting propagation of the tear is isolated from experimental results to obtain interface-CZM damage parameters. The interface CZM parameters are subsequently utilized in an FEM model to simulate macroscopic composite behavior to find good correlation. The experimental framework established in this paper can be utilized to estimate interface parameters of any particulate-elastomer composites that exhibit finite strain behavior.
Lorentz violation, quantum tunneling, and information conservation *
Authors: Li Guo-Ping , He Ke-Jian , Chen Bing-Bing
Published: November 2020

In this paper, by introducing the Lorentz-invariance-violation (LIV) class of dispersion relations (DR) suppressed by the second power

, we investigated the effect of the LIV on the Hawking radiation of a charged Dirac particle based on tunneling from a Reissner-Nordström (RN) black hole. It was determined that the LIV speeds up black hole evaporation. As a result, the induced Hawking temperature was very sensitive to changes in the energy of the radiation particle. However, at the same energy level, it was insensitive to changes in the charge of the radiation particle. This is phenomenological evidence in support of the LIV-DR as a candidate for describing the effect of quantum gravity. Moreover, when the effect of the LIV was included, we discovered that the statistical correlations with the Planck-scale corrections between successive emissions could leak out information via radiation. We also determined that black hole radiation via tunneling is an entropy conservation process, and no information loss occurred during radiation, where the interpretation of the entropy of a black hole is addressed. Finally, we concluded that black hole evaporation is still a unitary process in the context of quantum gravity.
Complete study on polarization of

hadroproduction at QCD next-to-leading order *
Authors: Feng Yu , Gong Bin , Chang Chao-Hsi , Wang Jian-Xiong
Published: November 2020

By applying the nonrelativistic quantum chromodynamics factorization formalism to

hadroproduction, a complete analysis of the polarization parameters

,

, and

for the production is presented at QCD next-to-leading order. With the long-distance matrix elements extracted from experimental data for the production rate and polarization parameter

of

hadroproduction, our results provide a good description of the measured parameters

and

in both the helicity and Collins-Soper frames. In our calculations, the frame invariant parameter

is consistent in the two frames. Finally, we mention that there are discrepancies between the available experimental data and corresponding theoretical predictions for

.
Theory for quarkonium: from NRQCD factorization to soft gluon factorization *
Authors: Chen An-Ping , Ma Yan-Qing
Published: November 2020

We demonstrate that the recently proposed soft gluon factorization (SGF) is equivalent to the nonrelativistic QCD (NRQCD) factorization for heavy quarkonium production or decay, which means that, for any given process, these two factorization theories are either both valid or both violated. We use two methods to arrive at this conclusion. In the first method, we apply the two factorization theories to the physical process

. Our explicit calculation shows that both SGF and NRQCD can correctly reproduce the low energy physics of full QCD, and the two factorizations are thus equivalent. In the second method, by using equations of motion, we successfully deduce SGF from NRQCD effective field theory. By identifying SGF with NRQCD factorization, we establish relations between the two factorization theories and prove the generalized Gremm-Kapustin relation as a byproduct. Compared with the NRQCD factorization, the advantage of SGF is that it resums the series of relativistic corrections originating from kinematic effects to all powers, yielding better convergence of the relativistic expansion.
Phase space formulation of the Abelian and non-Abelian quantum geometric tensor
Authors: Gonzalez Diego , Gutiérrez-Ruiz Daniel , David Vergara J
Published: November 2020

The geometry of the parameter space is encoded by the quantum geometric tensor, which captures fundamental information about quantum states and contains both the quantum metric tensor and the curvature of the Berry connection. We present a formulation of the Berry connection and the quantum geometric tensor in the framework of the phase space or Wigner function formalism. This formulation is obtained through the direct application of the Weyl correspondence to the geometric structure under consideration. In particular, we show that the quantum metric tensor can be computed using only the Wigner functions, which opens an alternative way to experimentally measure the components of this tensor. We also address the non-Abelian generalization and obtain the phase space formulation of the Wilczek–Zee connection and the non-Abelian quantum geometric tensor. In this case, the non-Abelian quantum metric tensor involves only the non-diagonal Wigner functions. Then, we verify our approach with examples and apply it to a system of N coupled harmonic oscillators, showing that the associated Berry connection vanishes and obtaining the analytic expression for the quantum metric tensor. Our results indicate that the developed approach is well adapted to study the parameter space associated with quantum many-body systems.
Influence of cellulose II polymorph nanowhiskers on bio-based nanocomposite film from Jatropha oil polyurethane
Authors: SaifulAzry S O A , Chuah T G , Paridah M T , Aung M M , Ridzuan M A , Lee C H , Sariah S , Lee S H , Juliana A H
Published: November 2020

Green polyurethane from plant oil-based such as Jatropha oil has recently received attention due to its environmental friendliness and sustainability. With incorporation of nanocellulose even though at low loadings in polymer matrices has shown a significant improvement. However, limited research has been done on different cellulose nanowhisker (CNW) polymorphs and their impact on composites. A number of studies have shown that the handling of cellulose polymorph also improves the properties of composite products as the cellulose II is more chemically reactive and thermodynamically stable than cellulose I. The aim this study is to investigate the effect of CNW with cellulose II polymorph in Jatropha oil-based polyurethane (JOPU). Different weight percent of CNW-II (0.1–1.5 wt%) were incorporated into JOPU films using vacuum rotavap and film casting. The total weight of 6 g was used as a fixed ratio (1:3) matrix of 4.4’-diphenyl-methane diisocyanate (MDI) and Jatropha-oil polyol (JO). The acid hydrolysis process was subjected to mercerised microcrystalline cellulose (MMCC) for the production of CNW-II. X-ray diffraction analyses were carried out to confirm cellulose II lattice of CNW-II. The CNW-II morphology was analysed using the transmission electron microscope. It was found that CNW-II had a granule-like shape with an average size of 74.04 nm in length and 21.36 nm in width. The translucency and colour of the film have also been tested by optical light microscopes. The clarity of the film and colour found affected by the highest CNW-II film loading. Based on the FTIR analysis, the spectra of all films show a typical polyurethane pattern that JOPU spectra found dominant due to very low volume NCW-II content in film. The same trend is observed for thermal degradation tested using a thermogravimetric analyser. Tensile strength and water uptake have been shown to increase in proportion to the CNW-II content.
Tunnelling measured with ultracold atoms
Authors: Ball Philip
Published: November 2020

Researchers have determined the time taken for an atom to tunnel through a laser beam, which could have implications for quantum technologies, as Philip Ball reports
Starspots show why some red giants spin faster than others
Authors: Jarman Sam
Published: November 2020

Some red-giant stars are rotating much faster than previously thought, according to an analysis led by Patrick Gaulme from the Max Planck Institute for Solar System Research in Göttingen, Germany.
Earth’s atmosphere rings like giant bell
Authors: Randall Ian
Published: November 2020

The Earth’s entire atmosphere vibrates like a giant bell, with various large-scale resonant waves travelling in both directions around the globe.
Weather forecasts hit by COVID-19 pandemic
Authors: Allen Michael
Published: November 2020

The grounding of commercial air flights during the COVID-19 pandemic has made weather forecasts less reliable and could stymie early warnings of extreme weather. That is according to an analysis by Ying Chen, an environmental scientist at Lancaster University in the UK.
Particle and atomic physics more likely to win Nobels
Authors: Perks Simon
Published: November 2020

Research into particle and atomic physics is more likely to be awarded a Nobel prize than work in other fields. That is according to a new analysis from scientists at Stanford University.
Broken cable damages iconic Arecibo observatory
Authors: Banks Michael
Published: November 2020

The iconic Arecibo radio telescope in Puerto Rico has suffered a 30 m-long gash in its main reflector dish after a steel cable snapped last month.
Therapeutics firms share inaugural IOP health prize
Authors: Harris Margaret
Published: November 2020

Two companies that use physics to unlock next-generation drugs for respiratory disorders and enable advanced cancer treatments are the first recipients of a new award from the Institute of Physics (IOP) for early-stage businesses in healthcare and medicine.
Hacking a path to innovation
Authors: Tsim Bonnie
Published: November 2020

Bonnie Tsim says “hackathons” are a great way for scientists to apply their skills to the commercial world
Higgs hardships
Authors: Jacoby Mike
Published: November 2020

In response to Niki Bell’s Forum article “Putting new physics on the syllabus” (August 2020), in which she suggests adding modern physics discoveries to the education syllabus.
How modelling is transforming medicine
Authors: Vennin Sam
Published: November 2020

Computational modelling has been brought under the spotlight during the COVID-19 pandemic, with scientists trying to predict how the SARS-CoV-2 virus will spread. But epidemiology is not the only medical field in which modelling is sparking breakthroughs, as Sam Vennin explains
Build a bot
Authors: Randall Ian
Published: November 2020

iCub was developed to explore the notion that the development of a truly human-like artificial intelligence is dependent on it having a physical body. The rationale for the hypothesis is at the heart of computer scientist Mark Lee of the University of Aberystwyth’s new book, How to Grow a Robot: Developing Human-Friendly, Social AI.
Cytomorphologic Features Found in Cerebrospinal Fluid Specimens of Hemophagocytic Lymphohistiocytosis Patients
Authors: Shyu Susan , Luca Dragos , VandenBussche Christopher J , Ho Cheng-Ying
Published: November 2020

Objectives

Central nervous system involvement is present in 70% of patients with hemophagocytic lymphohistiocytosis (CNS-HLH). CNS-HLH is defined by neurologic deficits, neuroimaging abnormalities, or positive cerebrospinal fluid (CSF) findings. The CSF cytomorphologic spectrum of CNS-HLH, however, has not been well investigated.

Methods

A retrospective review was performed on 64 CSF specimens from pediatric and adult patients with HLH. Ten patients had clinicoradiologic evidence of CNS involvement.

Results

We identified five CSF cytomorphologic patterns: (1) hemophagocytosis, (2) vacuolated macrophages without evidence of hemophagocytosis, (3) monocytes and/or nonvacuolated macrophages, (4) acellular specimens, and (5) bloody specimens. Patterns 1 and 2 were common in CNS-HLH and rare in patients without CNS involvement. The CSF cytomorphologic patterns did not correlate well with WBC counts or protein concentration.

Conclusions

Our study offers a comprehensive view of the cytomorphologic features seen in CSF specimens from patients with HLH.
Delta-gamma phase-amplitude coupling as a biomarker of postictal generalized EEG suppression
Authors: Grigorovsky Vasily , Jacobs Daniel , Breton Vanessa L , Tufa Uilki , Lucasius Christopher , del Campo Jose Martin , Chinvarun Yotin , Carlen Peter L , Wennberg Richard , Bardakjian Berj L
Published: November 2020

Postictal generalized EEG suppression is the state of suppression of electrical activity at the end of a seizure. Prolongation of this state has been associated with increased risk of sudden unexpected death in epilepsy, making characterization of underlying electrical rhythmic activity during postictal suppression an important step in improving epilepsy treatment. Phase-amplitude coupling in EEG reflects cognitive coding within brain networks and some of those codes highlight epileptic activity; therefore, we hypothesized that there are distinct phase-amplitude coupling features in the postictal suppression state that can provide an improved estimate of this state in the context of patient risk for sudden unexpected death in epilepsy. We used both intracranial and scalp EEG data from eleven patients (six male, five female; age range 21–41 years) containing 25 seizures, to identify frequency dynamics, both in the ictal and postictal EEG suppression states. Cross-frequency coupling analysis identified that during seizures there was a gradual decrease of phase frequency in the coupling between delta (0.5–4 Hz) and gamma (30+ Hz), which was followed by an increased coupling between the phase of 0.5–1.5 Hz signal and amplitude of 30–50 Hz signal in the postictal state as compared to the pre-seizure baseline. This marker was consistent across patients. Then, using these postictal-specific features, an unsupervised state classifier—a hidden Markov model—was able to reliably classify four distinct states of seizure episodes, including a postictal suppression state. Furthermore, a connectome analysis of the postictal suppression states showed increased information flow within the network during postictal suppression states as compared to the pre-seizure baseline, suggesting enhanced network communication. When the same tools were applied to the EEG of an epilepsy patient who died unexpectedly, ictal coupling dynamics disappeared and postictal phase-amplitude coupling remained constant throughout. Overall, our findings suggest that there are active postictal networks, as defined through coupling dynamics that can be used to objectively classify the postictal suppression state; furthermore, in a case study of sudden unexpected death in epilepsy, the network does not show ictal-like phase-amplitude coupling features despite the presence of convulsive seizures, and instead demonstrates activity similar to postictal. The postictal suppression state is a period of elevated network activity as compared to the baseline activity which can provide key insights into the epileptic pathology.
The prognostic nutritional index on postoperative day one is associated with one-year mortality after burn surgery in elderly patients
Authors: Seo Young Joo , Kong Yu-Gyeong , Yu Jihion , Park Ji Hyun , Kim Su-Jin , Kim Hee Yeong , Kim Young-Kug
Published: November 2020

Background

Burn injury in elderly patients can result in poor outcomes. Prognostic nutritional index (PNI) can predict the perioperative nutritional status and postoperative outcomes. We aim to evaluate the risk factors, including PNI, for one-year mortality after burn surgery in elderly patients.

Methods

Burn patients aged ≥65 years were retrospectively included. PNI was calculated using the following equation: 10 × serum albumin level (g/dL) + 0.005 × total lymphocyte count (per mm3). Cox regression, receiver operating characteristic curve and Kaplan–Meier survival analyses were performed to evaluate the risk factors for postoperative one-year mortality.

Results

Postoperative one-year mortality occurred in 71 (37.6%) of the 189 elderly burn patients. Risk factors for one-year mortality were PNI on postoperative day one (hazard ratio (HR) = 0.872; 95% CI = 0.812–0.936; p < 0.001), Sequential Organ Failure Assessment score (HR = 1.112; 95% CI = 1.005–1.230; p = 0.040), American Society of Anesthesiologists physical status (HR = 2.064; 95% CI = 1.211–3.517; p = 0.008), total body surface area burned (HR = 1.017; 95% CI = 1.003–1.032; p = 0.015) and preoperative serum creatinine level (HR = 1.386; 95% CI = 1.058–1.816; p = 0.018). The area under the curve of PNI for predicting one-year mortality after burn surgery was 0.774 (optimal cut-off value = 25.5). Patients with PNI ≤25.5 had a significantly lower one-year survival rate than those with PNI >25.5 (32.1% vs 75.9%, p < 0.001).

Conclusions

PNI on postoperative day one was associated with postoperative one-year mortality in elderly burn patients. The postoperative one-year survival rate was lower in patients with PNI ≤25.5 than in those with PNI >25.5. These findings indicate the importance of identifying elderly burn patients with low PNI, thereby reducing the mortality after burn surgery.
Pharmacoepidemiology for nephrologists (part 2): potential biases and how to overcome them
Authors: Fu Edouard L , van Diepen Merel , Xu Yang , Trevisan Marco , Dekker Friedo W , Zoccali Carmine , Jager Kitty , Carrero Juan Jesus
Published: November 2020

Observational pharmacoepidemiological studies using routinely collected healthcare data are increasingly being used in the field of nephrology to answer questions on the effectiveness and safety of medications. This review discusses a number of biases that may arise in such studies and proposes solutions to minimize them during the design or statistical analysis phase. We first describe designs to handle confounding by indication (e.g. active comparator design) and methods to investigate the influence of unmeasured confounding, such as the E-value, the use of negative control outcomes and control cohorts. We next discuss prevalent user and immortal time biases in pharmacoepidemiology research and how these can be prevented by focussing on incident users and applying either landmarking, using a time-varying exposure, or the cloning, censoring and weighting method. Lastly, we briefly discuss the common issues with missing data and misclassification bias. When these biases are properly accounted for, pharmacoepidemiological observational studies can provide valuable information for clinical practice.
Thermal tolerance and fish heart integrity: fatty acids profiles as predictors of species resilience
Authors: Christen Felix , Dufresne France , Leduc Gabriel , Dupont-Cyr Bernard A , Vandenberg Grant W , Le François Nathalie R , Tardif Jean-Claude , Lamarre Simon G , Blier Pierre U
Published: November 2020

The cardiovascular system is a major limiting system in thermal adaptation, but the exact physiological mechanisms underlying responses to thermal stress are still not completely understood. Recent studies have uncovered the possible role of reactive oxygen species production rates of heart mitochondria in determining species’ upper thermal limits. The present study examines the relationship between individual response to a thermal challenge test (CTmax), susceptibility to peroxidation of membrane lipids, heart fatty acid profiles and cardiac antioxidant enzyme activities in two salmonid species from different thermal habitats (Salvelinus alpinus, Salvelinus fontinalis) and their hybrids. The susceptibility to peroxidation of membranes in the heart was negatively correlated with individual thermal tolerance. The same relationship was found for arachidonic and eicosapentaenoic acid. Total H2O2 buffering activity of the heart muscle was higher for the group with high thermal resistance. These findings underline a potential general causative relationship between sensitivity to oxidative stress, specific fatty acids, antioxidant activity in the cardiac muscle and thermal tolerance in fish and likely other ectotherms. Heart fatty acid profile could be indicative of species resilience to global change, and more importantly the plasticity of this trait could predict the adaptability of fish species or populations to changes in environmental temperature.