bluuebunny/crossref_metadata_2025 huggingface dataset:
NORMAL-DEPENDENT TERMS IN WAVE EQUATIONS IN INTERACTION REPRESENTATION
Authors: CHANG TSUNG-SUI  ,   中国科学院数学研究所
Published: November 2020

The aim of this short paper is:( i ) To provide a rigorous proof for the deduction of the well-known equation i(δψ[σ])/(δσ(x))=V(x,σ)ψ[σ] (1) from the formulation of ordinary Schroedinger wave equations for wave functions on arbitrary space-like surfaces as given by Weiss and the author, and (ii) To study under what conditions the operator V in the above equation does not contain σ explicitly.To prove (1) from Weiss's theory, all that is necessary is to transform away the free Hamiltonian in the usual way and to prove that, according to the resulting wave equation, the difference of ψ on two adjacent surfaces which are different only in a small neighbourhood of σ certain point on the surfaces is proportional to the volume included between the surfaces. This is actually achieved. The terms in V which depend explicitly on a are worked out in terms of the total Lagrangian L and the interaction Lagrangian LI, i.e. 1/2Nμ(?LI)/(?φμα) GαβNν(?LI)/(?φνβ), (2) where φ1,φ2, …are the various field quantities, φμα denotes (?φα)/?xμ,Nμ denotes the surface normal and Gαβ are quantities defined by NμNν(?2L)/(?φμα?φνβ)Gβγ=δαγ. For the special case in which there is only one φ, the condition for V not to contain σ explicitly reduces to (?LI)/(?φμ)(?LI)/(?φν)/(?LI)/(?φρ)(?LI)/(?φρ)=(?2L)/(?φμ?φν)/(?2L)/(?φρ?φρ).
A CURRENT STABLIZER FOR β-RAY SPECTROMETER
Authors: HSI TEH-MING  , MEI JBNN-YUEH  ,   中国科学院物理研究所
Published: November 2020

The current stablizer, reported in this paper, is part of a β-ray spectrometer. Principally, it can also be used in other apparatus requiring stablized current. The stablizer can supply a maximum current of 100 A with a degree of stablity of 0.02% in ten minutes.We adopt the principle of negative feed back sevo-control in designing the stablizer. Firstly, the error signal of the DC current passing through a standard resistance is amplified. In order to avoid the drift effect of the usual DC amplifier, we use a bridge type balanced modulator to convert DC signal into AC signal. After AC amplification, the signal is demodulated by a phase sensitive demodulator. The amplification required is about 2×l04. Concerning the amplifier, the following problems are considered in detail: to keep the output of the modulator in zero potential while there is no input signal, the effect of the carrier component of the modulator, and the distortion of the modulated signal after amplification. After power amplification, the amplified signal is used to control the field supply of the DC generator. As there are capacitance and inductance in the system, the transmission of the signal in the system has time delay. In closed system, there is the possibility of instability of the nature of low frequency oscillation, and it is necessary to insert proper network in the system to suppress the oscillation. Finally, the detailed arrangements of the different components of the stablizer, its characteristics, and result of its operation are described.
A PHASE DIAGRAM OF THE SILVER-RICH ALLOYS OF THE TERNARY SYSTEM OF SILVER-TIN-ALUMINIUM
Authors: C. S. CHENG  , S. J. HUANG  , S. S. CHEN  , T. M. CHEN  , K. S. KAN  ,   东北人民大学物理系
Published: November 2020

The phase diagram of the silver-rich alloys of the ternary system of Silver-Tin-Aluminium, containing up to 30 wt% tin and up to 30wt% aluminium, has been studied by X-ray and microscopic methods.The phase section at room temperature was found to consist of four single-phase [i. e. a (cubic f. c.), μ (β-Mn), β (hexagonal) and γ (rhombohedral)] regions, five two-phase (i. e. α+β, α + μ ,β + μ ,β+γ and β+δ) regions and two three-phase (i. e. α+β+μ and β+γ+δ) regions. The four single-phase's appeared are exactly the same as those existing in the binary systems of Silver-Tin and Silver-Aluminium.
Simulation and analysis of melting behavior of local atomic structure of refractory metals vanadium
Authors: Jiang Yuan-Qi ,   Department of Physics, Nanchang Normal University, Nanchang 330032, China,   College of Physics, Jilin University, Changchun 130012, China
Published: November 2020

By using large-scale atomic/molecular massively parallel simulator (LAMMPS) code, a molecular dynamics simulation is performed in the NPT ensemble at zero pressure to investigate the influence of melting rates γ on the evolutional characteristics of vanadium atomic structure such as body-centered cubic (BCC), hexagonal close-packed structure (HCP), face centered cubic (FCC), simple cubic (SC) and icosahedra (ICO) during the rapid melting of solid vanadium crystal at five different melting rates (γ1 = 1 × 1011 K/s, γ2 = 1 × 1012 K/s, γ3 = 1 × 1013 K/s, γ4 = 1 × 1014 K/s , γ5 = 1 × 1015 K/s), in which 16000 atoms in a cubic box under the periodic boundary condition are considered, and their motion equations are solved by Verlet’s algorithm in the velocity form in time steps of 1 fs. Constant pressure P and temperature T are imposed by a modified Nose-Hoover method for both P and T variables, and an embedded-atom model (EAM) potential is utilized. For identifying the local atomic structures of liquid and solid vanadium at different temperatures, a polyhedral template matching method (PTMM) is used by measuring the root-mean square deviation (RMSD), in which clusters are classified as the topology of the local atomic environment without any ambiguity in the classification. Subsequently, the variation of the potential energy, entropy and Gibbs free energy of FCC, HCP, BCC and ICO vanadium clusters are calculated through ab initio MD simulation in the canonical ensemble (NVT) at selected temperatures, and the lowest-energy dynamic structure and its corresponding static heating structure are also shown in this paper. Based on the above calculated results, it is found that the melting point of refractory metal vanadium increases obviously with the increase of heating rate, but the heating rate only presents a limited effect on the population of atomic structure for each of BCC, HCP, FCC, SC and ICO. Namely, the temperature still plays a dominant role in the rapid melting process of V rather than heating rate. Moreover, the ab initio MD simulation and thermodynamics analysis further reveal that lots of ICO clusters of vanadium can exist stably in the liquid region rather than in solid crystal, which is not only due to its higher stability and longer lifetime than those of crystalline atomic clusters, but also because ICO possesses higher entropy and lower Gibbs free energy in high temperature liquid region.
Measurement of atmospheric water vapor vertical column concentration and vertical distribution in Qingdao using multi-axis differential optical absorption spectroscopy
Authors: Ren Hong-Mei , Li Ang , Hu Zhao-Kun , Huang Ye-Yuan , Xu Jin , Xie Pin-Hua , Zhong Hong-Yan , Li Xiao-Mei ,   Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China,   University of Science and Technology of China, Hefei 230026, China,   CAS Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China,   Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
Published: November 2020

The method of retrieving the vertical column density (VCD) and the atmospheric vertical profile of water vapor in visible blue band (434.0–451.5 nm) were studied by using the multi-axis differential optical absorption spectroscopy (MAX-DOAS). First, the method of retrieving the VCD of water vapor was studied. Owing the the fact that the water vapor absorption cross section is of high resolution and it cannot be effectively measured by MAX-DOAS, a convolved cross section with the instrument slit function was used. In addition, the correction factor for water vapor saturation absorption was also used to obtain the true VCD. Second, the water vapor profile retrieved by applying the nonlinear optimal estimation of the trace gas retrieval method (PriAM) was studied, including the effects of aerosol state and the priori profile on the water vapor retrieval. Influence on the water vapor retrieval from the aerosol prior profile linear changes was unapparent. High aerosol state has a significant influence on the water vapor profile retrieval and it was still within the total error tolerance. This indicates that the PriAM is applicable in the water vapor profile retrieval. Using this method, a continuous observation experiment was carried out at the MAX-DOAS Aoshan regional station in Qingdao. The retrieved water vapor VCD results were compared with the daily average data of the European Centre for Medium-Range Weather Forecasts (ECMWF), and the R2 is 0.93. The comparison of the near-surface water vapor concentration of MAX-DOAS retrieval with the ECMWF and sounding data of the University of Wyoming shows that R2 is larger than 0.70 and 0.66, respectively. The two comparison results demonstrate that PriAM can retrieve the atmospheric water vapor VCD and profile accurately. The vertical distribution characteristics of water vapor in Qingdao was analyzed, and the profile results show that the concentration of water vapor in Qingdao was distributed mainly under 1.5 km in height.
Method of accelerating convergence for gas kinetic algorithm based on digital constitutive relation of macroscopic equations
Authors: Pi Xing-Cai , Zhu Lian-Hua , Li Zhi-Hui , Peng Ao-Ping , Zhang Yong-Hao ,   Hypervelocity Aerodynamics Institute, China Aerodynamics Research and Development Center, Mianyang 621000, China,   James Weir Fluids Laboratory, Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ, UK,   National Laboratory for Computational Fluid Dynamics, Beijing 100191, China
Published: November 2020

In the simulation of complex multi-scale flows covering various flow regimes, the computational efficiency of gas kinetic method by which the evolution equation of velocity distribution function is solved directly is the key to engineering applications. In order to accelerate simulation for steady flows, a gas kinetic algorithm accelerated by utilizing the macroscopic conservative equations with a digital constitutive relation is developed. In this algorithm, the contribution of the high-order terms of stress and heat flux in macroscopic conservative equations is determined by the gas kinetic solution. Meanwhile, the solution of the macroscopic conservative equations provides the macroscopic quantities for the equilibrium distribution function in the Boltzmann model equation, where a fully implicit scheme to solve the Boltzmann model equation is developed.

Extensive validations are performed for the cavity flow, the supersonic flow around the cylinder, and the interactive rarefied flow around two side-by-side cylinders. The results from the above method are in good agreement with the results from the conventional gas kinetic unified algorithm and the direct simulation Monte Carlo method. It can be concluded that the nonlinear constitutive relation of rarefied flow can be well captured by the present method. And the ability of this method to simulate complex flows such as shock wave, strong wall shear and flow separation is demonstrated. Furthermore, the present method has shown to be much faster than the conventional gas kinetic unified algorithm, especially for the low-Kn flows. As the value of Kn increases, the acceleration rate decreases, because the effect of flow convection becomes weak. Meanwhile, more effort is needed to reduce inner loop iterations to improve its efficiency.
Design and coupling characteristics of terahertz dual-core anti-resonant fiber
Authors: Zhang Yao , Sun Shuai , Yan Zhong-Bao , Zhang Guo , Shi Wei , Sheng Quan , Fang Qiang , Zhang Jun-Xiang , Shi Chao-Du , Zhang Gui-Zhong , Yao Jian-Quan ,   College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China,   Key Laboratory of Optoelectronic Information Science and Technology (Ministry of Education), Tianjin University, Tianjin 300072, China,   Tianjin Institute of Modern Laser & Optics Technology, Tianjin 300384, China
Published: November 2020

The THz wave has good photonic and electronic properties, and has high penetration for non-polar materials, but its own photon energy is low. In addition, the THz wave also has characteristics such as wide bandwidth and large communication capacity, thereby making the THz wave possess important academic value and wide application prospects in the fields of non-destructive testing, biomedical imaging and communication. The development of THz technology requires not only high-performance THz waveguide technology for efficient transmission of THz waves, but also important optical devices such as optical switches, modulators, and couplers that are suitable for THz bands. With the in-depth study of THz waveguide technology, researchers have proposed many high-performance THz waveguide structures, such as metal hollow core tube waveguide, parallel metal plate waveguide, photonic crystal fiber and microstructure hollow core fibers, among which hollow-core photonic crystal fibers and hollow-core anti-resonant fibers (HC-ARF) have developed rapidly in recent years. So far, THz single-mode single-polarization fiber and high-birefringence fiber have been widely studied, but the researches on the fiber structure and devices that realize THz wave directional coupling are relatively rare. In this paper, we study the influences of the arrangement and distribution of the inner and outer claddings of HC-ARF on transmission characteristics, and thus design a new type of THz dual-core anti-resonant fiber. Compared with ordinary quartz fiber couplers and dual-core photonic crystal fibers, it can utilize a relatively simple structure and achieve directional coupling above 2 THz. Using the finite element analysis method to theoretically analyze the loss characteristics and coupling characteristics of the fiber, it is found that HC-ARF changes the periodic arrangement and distribution of the inner cladding tube within a certain range, which can achieve mode leakage without affecting the fiber transmission characteristics. So the THz dual-core anti-resonant fiber can be designed by using the mode leakage coupling mechanism. By changing the core distance and core gap size, the directional coupling with a coupling length of 0.72 m is realized at a transmission frequency of 2.5 THz. This terahertz dual-core anti-resonance fiber will have an important application value in terahertz optical devices such as terahertz optical switches, modulators and couplers.
Terahertz emitters based on ultrafast spin-to-charge conversion
Authors: Su Yu-Lun , Wei Zheng-Xing , Cheng Liang , Qi Jing-Bo ,   State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 611731, China,   Guangdong Institute of Electronic Information Engineering, University of Electronic Science and Technology, Dongguan 523808, China
Published: November 2020

Terahertz technology shows great potential applications in imaging, sensing and security. As is well known, the conventional solid-state broadband terahertz sources rely primarily on the nonlinear optical crystals and photoconductive antennas. Therefore, one major challenge for the next generation of terahertz technology is to develop the high-efficient, ultra-broadband and low-cost terahertz sources. In recent years, much attention has been paid to the spintronic terahertz emitters made of the metallic magnetic heterostructures on a nanometer scale. In this paper, the underlying physical mechanisms associated with this type of terahertz emitter is discussed. They mainly include the ultrafast demagnetization and the spin-charge interconversion processes. In order to further improve the terahertz emission efficiency, three main aspects are considered: appropriate choice of the materials (including conditions of the sample growing), film thickness, and new structure design. In the end, a short conclusion and future perspective for this research direction are given briefly.
Synthesis of photonic crystal fiber based on graphene directly grown on air-hole by chemical vapor deposition
Authors: Wang Xiao-Yu , Bi Wei-Hong , Cui Yong-Zhao , Fu Guang-Wei , Fu Xing-Hu , Jin Wa , Wang Ying ,   Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province, School of Information Science and Engineering, Yanshan University, Qinhuangdao 066004, China
Published: November 2020

The integration of fiber with graphene has greatly expanded the two-dimensional functional materials in the field of photonics research. However, the growth method by using chemical vapor deposition with metal catalytic substrateis limited to the fabrication of a graphene-fiber composite due to inevitably transferring graphene flakes onto the optical fiber surface. In order to fully achieve the interaction between light and graphene material, optical fibers have to be treated with special structure, which greatly damages the fiber structure, resulting in inefficient and harmful manufacturing strategy for the mass production. In this paper, a graphene-photonic crystal fiber (G-PCF) composite is prepared by atmospheric chemical vapor deposition (APCVD), which can directly grow monolayer and multi-layer graphene into the air-hole of photonic crystal fiber. Furthermore, we randomly break a G-PCF and then conduct an electron microscope (SEM) test at the fractured section. It is obvious that a tube-like graphene protruding out of one hole in the fractured area of the G-PCF is observed, thus further demonstrating that a monolayer graphene is grown on the inner hole walls of the PCF as shown in Fig. 2. By changing the process parameters such as growth temperature, duration and gas flow rate of carbon source, the law of the influence of different parameters on the graphene layers is explored. In addition, the uniformity of graphene and defects in the graphene-photonic crystal fiber(G-PCF) are experimentally analyzed. As illustrated in Fig. 7, a 4-cm-long uniform graphene-photonic crystal fiber sample is achieved by controlling the gas flow rate, growth time and the growth temperature. The APCVD method of directly growing graphene onto the inner hole walls of the PCF is simple and effective. The flexible structure and optical control enable the G-PCF to have great potential applications in all-optical devices and photonics. The development of high-quality graphene synthesis and opto-electronics technology ensures its compatibility with the integrated electronics platform and existing optical fiber systems. Moreover, our results will pave the way for 2D materials and optical fiber applications, providing a new idea for the application of graphene to the integration of all-optical fibers.
Research progress of wide bandgap perovskite materials and solar cells
Authors: Cui Xing-Hua , Xu Qiao-Jing , Shi Biao , Hou Fu-Hua , Zhao Ying , Zhang Xiao-Dan ,   Institute of Photoelectronic Thin Film Devices and Technology, Nankai University, Tianjin 300350, China,   Key Laboratory of Photoelectronic Thin Film Devices and Technology of Tianjin, Tianjin 300350, China,   Engineering Research Center of Thin Film Photoelectronic Technology, Ministry of Education, Tianjin 300350, China,   Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China,   Renewable Energy Conversion and Storage Center of Nankai University, Tianjin 300072, China
Published: November 2020

Organic-inorganic metal halide perovskites are a new type of photovoltaic material, they have attracted wide attention and made excellent progress in recent years. The power conversion efficiency of a single-junction perovskite solar cell has been increased to 25.2% just within a decade. Meanwhile, crystalline silicon solar cells account for nearly 90% of industrialized solar cells and have a maximum efficiency of 26.7%, approaching to their theoretical limit. It is more difficult to further improve the efficiency of single junction solar cells. It has been shown that multi-junction tandem solar cells prepared by stacking absorption layers with different bandgaps can better use sunlight, which is one of the most promising strategies to break the efficiency limitation of single-junction solar cells. Due to the bandgap tunability and low-temperature solution processability, perovskites stand out among many other materials for manufacturing multi-junction tandem solar cells. Wide bandgap perovskites with a bandgap of 1.63 eV or above have been combined with narrow band gap inorganic absorption layers such as silicon, copper indium gallium selenide, cadmium telluride or narrow bandgap perovskite to produce high efficiency tandem solar cells. In addition to the promoting of the efficiency improvement of solar cells, the wide bandgap perovskites have broad applications in photovoltaic building integration and photocatalytic fields. Therefore, it is very important to explore and develop high quality wide bandgap perovskite materials and solar cells. Unfortunately, the wide bandgap perovskites have several intrinsic weaknesses, including being more vulnerable to the migration of halogen ions under being illuminated, more defects, and greater possibility of energy level mismatching with the charge transport layers than the narrow bandgap counterparts, which limits the further development of the wide bandgap perovskite solar cells. In this review, the development status of wide bandgap perovskite solar cells is summarized and corresponding strategies for improving their performance are put forward. Furthermore, some personal views on the future development of wide bandgap perovskite solar cells are also presented here in this paper.
STATISTICAL THEORY OF SUPERLATTICES OF THE TYPE AB IN A QUADRATIC AND A SIMPLE CUBIC LATTICE
Authors: YEE-CHUANG HSU  ,   Department of Physics,National Tsing Hua University
Published: November 2020

Wang's generalization of Bethe's theory of snperlattices is applied to the cases of quadratic and simple cubic lattice. Only neighbour interaction is taken into consideration. All the calculations are carried out to the second approximation.The variation of the critical temperature with composition is calculated. The degree of order, the energy and the specific heat are calculated for the special case of equal numbers of A and B atoms at various temperatures. It is found that the results differ very little from those obtained by Bethe in the second approximation. In the case of the simple cubic lattice the discontinuity of the specific heat is found to be only slightly larger than that obtained by Bethe.
ON THE BINDING ENERGIES OF THE NUCLEI 6Li AND 7Li——PART I. GENERAL FORMULATION (Contributions from Institute of Modern Physics, Academia Sinica, No. 3)
Authors: KING SING-NAN  ,   中国科学院近代物理研究所
Published: November 2020

By using the nuclear potential obtained by Peng and Chang as a working hypothesis, we have obtained the general formulae for computing the binding energies of 6Li and 7Li, the wave functions being approximated by those of a definite shell formation of the nucleons.
THE DENSITY OF HEAVY WATER BETWEEN 25°AND 100℃.
Authors: TSING-LIEN CHANG  , LU-HO TUNG  ,   Department of Chemistry,National Tsing Hua University. Peiping.
Published: November 2020

The density of heavy water has been determined between 25° and 100℃. Using the known data below 25°, we are able to construct a density table for heavy water between its freezing and boiling points with an accuracy of five units in the fifth decimal place. Figures are given to show the density difference between heavy water and ordinary water and also their density ratio, which tends to pass over a maximum at a temperature not far above the boiling point.
MEASUREMENT OF PHASE ANGLE BETWEEN FUNDAMENTAL COMPONENTS OF TWO NON-SINUSOIDAL PERIODIC WAVES
Authors: PING-CHUAN FENG  ,   Department of Physics,Linguan University,Canton
Published: November 2020

This paper presents a simple method by which the phase angle between the fundamental components of two non-sinusoidal waves can be measured. Applications of this method in an electron tube amplifier and oscillator arc discussed.
ON WEISS'S THEORY OF FIELDS
Authors: T. S. CHANG  ,   Dept. of physics,Peking University
Published: November 2020

Weiss's theory on the change of Schr?dinger wave functional on a surface as the surface changes is given in a complete form, allowing the Lagrangian of the field to contain all derivatives of the field quantities. The integrability of the resulting equation is proved by making use of the fact that the corresponding Hamilton-Jacobi equation is integrable. This gives at the same time a proof of the Lorentz invariancy of the commutation relations between the various conjugate variables, which so far remained obscure as soon as we allow derivatives higher than the second of the field quantities to appear in the Lagrangian.
THE RECTIFYING CHARACTERS OF ORDINARY ELECTRIC BULBS
Authors: CHEN SHANG-YI  , LIU PEN-HSUN  ,   (1)Institute of Physics,National Academy of Peiping.; (2)Physics Department,Yenching University,Peiping.
Published: November 2020

Rectified current derivable from an electric bulb when it is painted with Chinese ipk has been observed. The rectifying characters of twenty three ordinary electric bulbs made by eleven different companies were studied. It was observed that the polarity of the rectified current derived from the surface of the bulb depends on the nature of the bulb and an explanation to account for the phenomenon has been attempted. Results showing the relation between the output and the input, the effect of the position of the paint on the bulb, the temperature, the composition of the paint and the nature of the bulb are given.
ON THE ADVANCED SOLUTION OF THE WAVE EQUATION
Authors: HSIN P. SOH  ,   浙江大学物理系
Published: November 2020

It is shown that the advanced solutions of the wave equation are identical with the retarded solutions when the boundary integrals are properly taken care of.
ON VOLUME VISCOSITY AND ACOUSTIC DISPERSION PHENOMENA
Authors: HOFF.LU  ,   浙江大学物理系
Published: November 2020

Our bulk-visco-elastic theory is extended to the case, as recently discovered in ultrasonic absorption measurements, in which there are present more than one relaxation times. This multi-relaxational theory is applied to the study of acoustic dispersion phenomena. The bearing of our relaxational theory in general on classical hydrodynamics is further examined. Illustrative calculations from certain available experimental data are given and their indications discussed.
STRUCTURE OF COLD-WORKED METALS AS DEDUCED FROM ANELASTIC MEASUREMENTS
Authors: T. S. KE  , C. Zener  ,   (1)清华大学物理系,中国科学院应用物理研究所; (2)芝加哥大学金属研究所
Published: November 2020

An attempt was made to interpret the structure of cold-worked metals in terms of the associated anelastic behavior. The specimen used in the study was 99.991 percent aluminum which was heavily cold-worked but partly recovered. Analysis showed that under the conditions of the experiments, namely, prior stabilization and low stress levels, measurement of creep under constant stress agree with the internal friction measurements previously reported. The creep curves obtained showed several striking features. The most striking feature of the data is the complete recoverability of the creep. We could thus conclude that no irreversible processes were occurring, such as the generation of dislocations. The second important feature is the large magnitude of the recoverable creep, being almost ten times the corresponding elastic deformation.The consideration of a heterogeneous network of slip bands in cold-worked metals led to a creep formula which closely represents the creep curves obtained. As the interpretation in terms of a dislocation model would require some ad hoc assumptions, we are led to conclude that the picture of a distribution of slip bands having a wide distribution in size is a closer approximation to the state of a heavily cold-worked metal specimen (partly recovered) than is the commonly presented picture of isolated dislocations.
A GAS DISCHARGE SWITCH:——II. FOR CONTROLLING LOW LEVEL 10 CM-BAND MICROWAVE SIGNALS
Authors: T. S. KE  ,   清华大学物理系,中国科学院应用物理研究所
Published: November 2020

Based on the interaction between r-f field and the electrons furnished from an auxiliary d-c discharge, a gas discharge switch has been developed for controlling low level 10 cm-band signals by modifying the keep-alive electrode of a cell type 1827 TR tube. It has been found that the attenuation was considerably increased when the top of the keep-alive electrode was off-center and close to the side of the lower hollow cylindrical post. Nitrogen or argon at a pressure of about 4 mm Hg was found to be appropriate as a gas filling for such a switch. An attenuation of more than 30 db was obtained from a tube having a keep-alive depth of 0.0 mm and a distance of 0.7 mm from the keep-alive to lowcr-hollow-cone. The gas filling was nitrogen at 4 mm Hg, and the keep-alive current was 1 ma with a d-e gap voltage of about 450 volts. Such a switch has a very long life, as there was no appreciable change in the tube behavior alter operating continuously for several hundred hours.
UPPER LIMITS OF THE FISSION CROSS-SECTIONS OF BISMUTH, LEAD, GOLD, PLATINUM AND TUNGSTEN FOR 21 MEV NEUTRONS
Authors: HO ZAH-WEI  ,   中国科学院近代物理研究所
Published: November 2020

The emulsion technique was used to set certain upper limits for the fission cross sections of some naturally occurring heavy elements bombarded with 21 Mev neutrons. It is established that the fission cross-sections for these elements (Bi, Pb. Au, Pt and W) are less than 4 X 10-5 of that of U238. These results are in disagreement with the fission threshold derived from the theory of fission based on the liquid drop model for heavy nuclei, but support a simple argument about the minimum neutron energy required to produce fission by Tsien San-Tsiang.
VARIATIONAL METHODS IN THE PROBLEM OF TORSION FOR MULTIPLY-CONNECTED DOMAINS
Authors: LIN HUNG-SUN  ,   中国科学院数学研究所
Published: November 2020

The problem of torsion of a prismatic body with multiply-connected, cross section is considered from the view-point of two basic variationa'l principles in the theory of elasticity, viz., the principle of minimum potential energy and the principle of complementary energy. According to the former, among all admissible states of strain, in the sense of being derived from sets of displacements chat satisify the specified displacement boundary conditions, the true state renders the potential energy of the system a minimum. In the latter, among all admissible states in the sense of satisfying the equilibrium conditions and the specified stress boundary conditions, the true state renders the complementary energy of the elastic body a minimum.
An Overview of the History of Projective Representations of Groups
Authors:   Marin Drinov  Academic Publishing House, Hirai Takeshi
Published: November 2020

An overview of the history of projective representations (= spin representations) of groups, preceded by the prehistory of studies on the theory of quaternion due to Rodrigues and Hamilton. Beginning with Schur, we cover many mathematicians until today, and also physicists Pauli and Dirac.
Bi-Lagrangian Structure on the Symplectic Affine Lie Algebra $\frak{aff}(2,\mathbb{R})$
Authors:   Marin Drinov  Academic Publishing House, Bouzour Omar , Mansouri Mohammed Wadia
Published: November 2020

In this paper, we give a complete classification of Lagrangian and bi-Lagrangian subalgebras, up to an inner automorphism on $\frak{aff}(2,\mathbb{R})$, and compute the curvatures of some bi-Lagrangian structures.
Slant Curve in Lorentzian BCV Spaces
Authors:   Marin Drinov  Academic Publishing House, Yildirim Abdullah
Published: November 2020

The aim of this study is to examine the slant curves in Lorentzian manifolds with BCV (Bianchi-Cartan-Vranceanu) metrics. A practical form of the directional derivative in the presence of the BCV metrics is presented. Moreover, some theorems for slant curves in Lorentzian BCV manifolds are proved.
Seed morphology and sculpture of invasive Impatiens capensis Meerb. from different habitats
Authors: Rewicz Agnieszka , Myśliwy Monika , Adamowski Wojciech , Podlasiński Marek , Bomanowska Anna
Published: November 2020

Impatiens capensis is an annual plant native to eastern North America that is currently spreading across Europe. In Poland, due to this plant’s rapid spread in the secondary range and high competitiveness in relation to native species, it is considered a locally invasive species. The microstructure of seeds is an important tool for solving various taxonomic problems and also provides data useful for determining the impact of various environmental factors on the phenotypic variability of species. This issue is particularly important in regard to invasive species which occupy a wide range of habitats in the invaded range. There are few reports on seed size and thus far no descriptions of the seed ultrastructure of I. capensis in the analyzed literature. We present new data on the seed morphology of I. capensis growing in different habitats and conditions in the secondary range of the species. The studied populations differed significantly in each of the investigated traits (seed length, width, circumference, area, roundness, and mass). Our findings showed that anthropogenic disturbances in habitats and some soil parameters (presence of carbonates, potassium, loose sand, and moisture) were statistically significant with various seed sizes and morphology in the studied populations of I. capensis. Moreover, our studies showed maximum seed length (5.74 mm) and width (3.21 mm) exceeding those values given in the available literature. For the first time, we also provide a detailed SEM study of the ultrastructure of the seed coat of I. capensis. There are two types of epidermal cells on the seeds: (a) between the ribs (elongated with straight anticlinal walls, slightly concave outer periclinal walls, and micropapillate secondary sculpture on the edges with anticyclic walls), and (b) on the ribs (isodiametric cells with straight anticlinal walls and concave outer periclinal walls). Unlike the variability of size and weight of seeds, the coat ornamentation has turned out to be a steady feature within the studied secondary range of I. capensis.
Adaptive divergence, neutral panmixia, and algal symbiont population structure in the temperate coral Astrangia poculata along the Mid-Atlantic United States
Authors: Aichelman Hannah E. , Barshis Daniel J.
Published: November 2020

Astrangia poculata is a temperate scleractinian coral that exists in facultative symbiosis with the dinoflagellate alga Breviolum psygmophilum across a range spanning the Gulf of Mexico to Cape Cod, Massachusetts. Our previous work on metabolic thermal performance of Virginia (VA) and Rhode Island (RI) populations of A. poculata revealed physiological signatures of cold (RI) and warm (VA) adaptation of these populations to their respective local thermal environments. Here, we used whole-transcriptome sequencing (mRNA-Seq) to evaluate genetic differences and identify potential loci involved in the adaptive signature of VA and RI populations. Sequencing data from 40 A. poculata individuals, including 10 colonies from each population and symbiotic state (VA-white, VA-brown, RI-white, and RI-brown), yielded a total of 1,808 host-associated and 59 algal symbiont-associated single nucleotide polymorphisms (SNPs) post filtration. Fst outlier analysis identified 66 putative high outlier SNPs in the coral host and 4 in the algal symbiont. Differentiation of VA and RI populations in the coral host was driven by putatively adaptive loci, not neutral divergence (Fst = 0.16, p = 0.001 and Fst = 0.002, p = 0.269 for outlier and neutral SNPs respectively). In contrast, we found evidence of neutral population differentiation in B. psygmophilum (Fst = 0.093, p = 0.001). Several putatively adaptive host loci occur on genes previously associated with the coral stress response. In the symbiont, three of four putatively adaptive loci are associated with photosystem proteins. The opposing pattern of neutral differentiation in B. psygmophilum, but not the A. poculata host, reflects the contrasting dynamics of coral host and algal symbiont population connectivity, dispersal, and gene by environment interactions.
Kinematic effects of the circle with and without rider in walking horses
Authors: Egenvall Agneta , Engström Hanna , Byström Anna
Published: November 2020

Background

Biomechanical studies of walk, especially walk on the circle, are scarce, while circles or curved tracks are frequently used during equestrian activities. To study horse–rider–circle interactions on the circle, the first steps would be to investigate how the unridden, freely walking horse is influenced by circular movement, and then add a rider. The aim was to study horse vertical trunk movements, and sagittal cannon angles (protraction–retraction) during walk in straight-line and on the circle without rider, and on the circle with a rider using minimal influence.

Methods

Ten horses were ridden by five riders, summing to 14 trials. Each trial included straight walk unridden (on concrete), and walk on 10 m diameter circles (left and right on soft surface) first lunged (unridden) and then ridden with minimal rider influence. Inertial measurement units (100 Hz) were positioned on the withers, third sacral vertebra (S3) and laterally on metacarpal and metatarsal bones (using self-adhesive bandage). Selected data were split in steps (withers and S3 vertical translations) or strides (cannon protraction–retraction) at maximum hind limb protraction, and range of motion (ROM), minima and maxima, and their timing, were extracted. Data were analyzed using mixed models with inner/outer/straight nested within unridden/ridden as fixed effect, and controlling for stride duration. Differences between: inner vs outer steps/limbs; the same step/limb unridden vs ridden; and the same step/limb straight vs inner/outer unridden; were examined for statistical significance atp< 0.05.

Results

Inner limbs had smaller cannon ROM than outer limbs, for example, forelimbs when ridden (inner vs outer 62° vs 63°) and hind limbs when unridden (53° vs 56°). Forelimb cannon ROM was the largest for straight (65°). Hind limb ROM for straight walk (55°) was in-between inner (52–53°) and outer hind limbs (56–57°). Vertical ROM of S3 was larger during the inner (unridden/ridden 0.050/0.052 m) vs the outer step (unridden/ridden 0.049/0.051 m). Inner (0.050 m) and outer steps (0.049 m) unridden had smaller S3 ROM compared to straight steps (unridden, 0.054 m). Compared to when unridden, withers ROM was smaller when ridden: inner hind steps unridden/ridden 0.020 vs 0.015 m and outer hind steps 0.020 vs 0.013 m. When ridden, withers ROM was larger during the inner hind step vs the outer.

Conclusion

The outer hind limb had greater cannon pro-retraction ROM, compared to the inner limb. Larger croup ROM during the inner step appears to be coupled to increased retraction of the outer hind limb. Knowledge of magnitudes and timing of the horse’s movements on the circle in unridden and ridden walk may stimulate riders to educate eye and feel in analyzing the execution of circles, and stimulate further studies of the walk, for example, on interactions with rider influence, natural horse asymmetries, or lameness.
Temporal trend of cardiorespiratory endurance in urban Catalan high school students over a 20 year period
Authors: Arboix-Alió Jordi , Buscà Bernat , Sebastiani Enric M. , Aguilera-Castells Joan , Marcaida Sergio , Garcia Eroles Luis , Sánchez López María José
Published: November 2020

Background

Physical fitness is considered an important indicator of health in adolescents. However, in recent years several studies in the scientific literature have shown a considerable lower trend and an alarming worsening of the current adolescents’ physical condition when comparing with previous decades, especially in urban populations. The aim of the current study was to analyse the temporal trend in cardiorespiratory endurance (CRE) in urban Catalan adolescents over a 20-year period (1999–2019).

Methods

A cross-sectional analysis study considering the 20-m Shuttle Run test (SRT) results obtained in the last 20 years was carried out. 1,701 adolescents between 15 and 16 years old (914 boys and 787 girls) were divided into four groups, corresponding to consecutive periods of five years (Group 1: 1999–2004; Group 2: 2005–2009; Group 3: 2010–2014 and Group 4: 2015–2019). ANOVA was used to test the period effect on CRE and post hoc Bonferroni analysis was performed to test pairwise differences between groups (p < 0.05).

Results

Results showed a significantly lower performance in CRE in both sexes. The percentual negative difference was 0.67%, 9.6% and 7% for boys and 5.06%, 14.97% and 9.41% for girls, when comparing the performance in 20-m Shuttle Run test for the first period, respectively.

Conclusions

Results suggest that the physical fitness of Catalan urban adolescents is lower in both sexes when comparing the different analysed periods of time. Therefore, CRE adolescents should be improved in order to help to protect against cardiovascular disease and other health risks in adulthood.
COVID-19 and Supply Chain Disruption: A Conceptual Review
Authors: Odunayo Akintokunbo, Oluwarotimi , Victor Adim, Chidiebere
Published: November 2020

COVID-19 crisis has created a new set of challenges to which supply chain managers must respond. As demand for home delivery services surge, supply chains have to adapt their supply replenishment processes, their order fulfilment processes and hire new employees to be trained in the specifics of order picking and home delivery. The COVID-19 pandemic has emerged as a significant health risk, and countries around the world have responded with partial shutdowns of their economies to slow the pace of infections. These measures have reportedly led to massive disruptions in the global and domestic supply chains. The findings in extant literature show that supply chains during COVID-19 are more fragile for products that travel long distances before reaching their final point of sale. Our work highlights how online data can be used in conjunction with other data-sets for real-time policymaking. This paper conceptually examines the impact of COVID-19 on supply chain disruption and response strategies adopted.
The ubiquitin ligase RNF8 regulates Rho GTPases and promotes cytoskeletal changes and motility in triple‐negative breast cancer cells
Authors: Pereira De Carvalho Bruno , Chern Yi‐Jye , He Jiabei , Chan Chia‐Hsin
Published: November 2020

The ubiquitin ligase RNF8 is known to induce epithelial‐to‐mesenchymal (EMT) transition and metastasis in triple‐negative breast cancer (TNBC). Besides EMT, Rho GTPases have been shown as key regulators in metastasis. In this study, we investigated the role of RNF8 in regulating Rho GTPases and cell motility. We find that RNF8 knockdown in TNBC cells attenuates the protein and mRNA levels of Ras homolog family member A (RHOA) and cell division cycle 42 (CDC42). We show that the formation of filopodia, focal adhesions, and the association of focal adhesions to stress fibers is impaired upon RNF8 knockdown. Cell migration is significantly inhibited by RNF8 knockdown. Our study suggests a potential novel role for RNF8 in mediating cell migration in TNBC through regulation of the Rho GTPases RHOA and CDC42.
Bayesian Methods for Tensor Regression
Authors: Guhaniyogi Rajarshi
Published: November 2020

For many applications pertaining to neuroimaging, social science, international relations, chemometrics, genomics, and molecular omics, datasets often involve variables which are best represented in the form of a multidimensional array ortensor, which extends the familiar two‐way data matrix into higher dimensions. Rather than vectorizing tensor‐valued variables prior to analysis which results in loss of inference, new methods have emerged developing regression relationships between variables with either tensor‐valued response(s) or predictor(s). Bayesian approaches, in particular, have shown great promise in applications pertaining to tensor regressions. A remarkable feature of fully Bayesian approaches is that they allow flexible modeling of tensor‐valued parameters in the regressions involving tensor variables and naturally offer characterization of uncertainty in the parametric and predictive inferences. This article provides a review of some relevant Bayesian models on tensor regressions developed in recent years. We divide methods according to the objective of the analysis. We begin with tensor regression approaches with a scalar response and a tensor‐valued covariate and discuss both parametric and nonparametric modeling options and applications in this framework. We then address the problem of making inference with a tensor response and a vector of covariates, with applications including task‐related brain activation and connectivity studies. Finally, we offer discussion on Bayesian models involving a tensor response and a tensor covariate. Discussion of each model is accompanied by available results on its posterior contraction properties, laying out restrictions on key model parameters (such as the tensor dimensions) to draw accurate posterior inference.
Image quality evaluation of intra‐irradiation cone‐beam computed tomography acquired during one‐ and two‐arc prostate volumetric‐modulated arc therapy delivery: A phantom study
Authors: Iramina Hiraku , Kitamura Ayaka , Nakamura Mitsuhiro , Mizowaki Takashi
Published: November 2020

Purpose

To evaluate (a) the effects of megavoltage (MV)‐scatter on concurrent kilovoltage (kV) projections (PMVkV) acquired during rotational delivery, and (b) the image quality of intra‐irradiation cone‐beam computed tomography (ii‐CBCT) images acquired during prostate volumetric‐modulated arc therapy (VMAT) delivery.

Methods

Experiment (1): PMVkVs were acquired with various MV beam parameters using a cylindrical phantom: field size (FS), MV energy (6 or 15 MV), dose rate (DR), and gantry speed. The average pixel values were calculated in a region on each PMVkV which were extracted at eight equally spaced gantry angles. Experiment (2): 11 one‐arc and seven two‐arc 15 MV prostate VMAT plans were used along with a pelvis phantom. One plan was selected from each of arc plans and its MV energy was changed to 6 MV. After PMVkVs were acquired, projections consisting of MV‐scatter only (PMVS) were acquired with closing kV blades and subtracted from PMVkV (PMVScorr). Projections by kV beams only were acquired (PkV). The corresponding CBCT images were reconstructed (CBCTMVkV, CBCTMVScorr, and CBCTkV). The root‐mean‐square errors (RMSEs) were calculated in prostate region and 3D gamma analysis was conducted, in which the CBCT‐number was used instead of doses between ii‐CBCT images and CBCTkV (30 HU/1 mm).

Results

Experiment (1): The MV‐scatters were dependent on the FSs, MV energies, and DRs. Experiment (2): The median RMSEs for CBCTMVScorr were decreased by 107.5 HU (1‐arc) and 42.9 HU (2‐arc) compared to those for CBCTMVkV. The median GPRs for CBCTMVScorr were 94.7% (1‐arc) and 93.4% (2‐arc), while those for CBCTMVkV were 61.1% and 79.9%, respectively. GPRs for 6 MV plans were smaller than those for 15 MV plans.

Conclusions

The number of MV‐scatters increased with larger FSs and DRs, and smaller MV energy. The MV‐scatters were corrected on the CBCTMVScorr regardless of the number of arcs.