bluuebunny/crossref_metadata_2025_split huggingface dataset:
Roadmap on biology in time varying environments
Authors: Murugan Arvind , Husain Kabir , Rust Michael J , Hepler Chelsea , Bass Joseph , Pietsch Julian M J , Swain Peter S , Jena Siddhartha G , Toettcher Jared E , Chakraborty Arup K , Sprenger Kayla G , Mora T , Walczak A M , Rivoire O , Wang Shenshen , Wood Kevin B , Skanata Antun , Kussell Edo , Ranganathan Rama , Shih Hong-Yan , Goldenfeld Nigel 
Published: January 2021

Abstract
Biological organisms experience constantly changing environments, from sudden changes in physiology brought about by feeding, to the regular rising and setting of the Sun, to ecological changes over evolutionary timescales. Living organisms have evolved to thrive in this changing world but the general principles by which organisms shape and are shaped by time varying environments remain elusive. Our understanding is particularly poor in the intermediate regime with no separation of timescales, where the environment changes on the same timescale as the physiological or evolutionary response. Experiments to systematically characterize the response to dynamic environments are challenging since such environments are inherently high dimensional. This roadmap deals with the unique role played by time varying environments in biological phenomena across scales, from physiology to evolution, seeking to emphasize the commonalities and the challenges faced in this emerging area of research.
A simplified Parisi ansatz
Authors: Franchini Simone 
Published: January 2021

Abstract
Based on simple combinatorial arguments, we formulate a generalized cavity method where the Random Overlap Structure (ROSt) probability space of Aizenmann, Sims and Starr is obtained in a constructive way, and we use it to give a simplified derivation of the Parisi formula for the free energy of the Sherrington–Kirkpatrick model.
Analytic continuation and reciprocity relation for collinear splitting in QCD *
Authors: Chen Hao , Yang Tong-Zhi , Zhu Hua-Xing , Zhu Yu-Jiao 
Published: January 2021

Abstract
It is well-known that direct analytic continuation of the DGLAP evolution kernel (splitting functions) from space-like to time-like kinematics breaks down at three loops. We identify the origin of this breakdown as due to splitting functions not being analytic functions of external momenta. However, splitting functions can be constructed from the squares of (generalized) splitting amplitudes. We establish the rules of analytic continuation for splitting amplitudes, and use them to determine the analytic continuation of certain holomorphic and anti-holomorphic part of splitting functions and transverse-momentum dependent distributions. In this way we derive the time-like splitting functions at three loops without ambiguity. We also propose a reciprocity relation for singlet splitting functions, and provide non-trivial evidence that it holds in QCD at least through three loops.
Confinement and the global SU(3) color symmetry *
Authors: Chen Ying 
Published: January 2021

Abstract
The global

color symmetry and its physical consequences are discussed. The Nöther current is actually governed by the conserved matter current of color charges if the color field generated by this charge is properly polarized. The color field strength of a charge can have a uniform part due to the nontrivial QCD vacuum field and the nonzero gluon condensate, which implies that the self-energy of a system with a net color charge is infinite and, therefore, cannot exist as a free state. This is precisely what color confinement means. Accordingly, the Cornell type potential with the feature of Casimir scaling is derived for a color singlet system composed of a static color charge and an anti-charge. The uniform color field also implies that a hadron has a minimal size and minimal energy. Furthermore, the global

color symmetry requires that the minimal irreducible color singlet systems can only be

,

,

,

,

,

,

, etc., therefore a multi-quark system can only exist as a molecular configuration if there are no other binding mechanisms.
Double-heavy tetraquark states with heavy diquark-antiquark symmetry *
Authors: Cheng Jian-Bo , Li Shi-Yuan , Liu Yan-Rui , Si Zong-Guo , Yao Tao 
Published: January 2021

Abstract
We calculate the masses of the

(

;

) tetraquark states with the aid of heavy diquark-antiquark symmetry (HDAS) and the chromomagnetic interaction (CMI) model. The masses of the highest-spin (

) tetraquarks that have only the

color structure are related with those of conventional hadrons using HDAS. Thereafter, the masses of their partner states are determined with the mass splittings in the CMI model. Our numerical results reveal that (i) the lightest

(

) is an

state around 3929 MeV (53 MeV above the

threshold), and none of the double-charm tetraquarks are stable; (ii) the stable double-bottom tetraquarks are the lowest

around 10488 MeV (

MeV below the

threshold) and the lowest

around 10671 MeV (

MeV below the

threshold); and (iii) the two lowest

tetraquarks, namely the lowest

around 7167 MeV and the lowest

around 7223 MeV, are in the near-threshold states. Moreover, we discuss the constraints on the masses of double-heavy hadrons. Specifically, for the lowest nonstrange tetraquarks, we obtain

MeV,

MeV, and

MeV.
Nucleon stripping in deuteron-induced spallation reactions at hundreds MeV/nucleon *
Authors: Song Qu-Fei , Xu Su-Yang , Su Jun 
Published: January 2021

Abstract
A nucleon-nucleus dynamics model was developed to investigate the proton-, neutron-, and deuteron-induced reactions at hundreds of MeV/nucleon. In this model, the trajectory of incident nucleon is described by classical mechanics, and the probability of reaction between the nucleon and nucleus is calculated by exponential damping. It is shown that the total reaction cross sections calculated by the model agree in general with the predictions by the CDCC and the experimental data. The model was applied to investigate the nucleon stripping in deuteron-induced reactions and its symmetry energy dependence.
News from the BIPM laboratories—2020
Authors: Wielgosz Robert , Tavella Patrizia , Judge Steven , Stock Michael , Milton Martin 
Published: January 2021

Abstract
In order to fulfil its mission to ensure and promote the global comparability of measurements, the BIPM operates laboratories in the fields of physical metrology, time, ionizing radiation and chemistry. These laboratories act as centres for scientific and technical collaboration between member states providing capabilities for international measurement comparisons on a shared cost basis. They coordinate international comparisons of national measurement standards agreed to be of the highest priority, and they establish and maintain appropriate reference standards for use as the basis of key international comparisons at the highest level and provide selected calibrations from them. The BIPM sustained all of its key activities throughout the periods of confinement resulting from the global pandemic in 2020 including: the publication of Circular T each month, the annual World Metrology Day celebrations and the launch of the new key comparison database (KCDB 2.0). Several activities were brought forward in the work programme including the automation of data handling in the International Reference System (SIR) for radionuclide metrology and on-line technical exchanges and capacity building initiatives. The BIPM has also worked to understand how best to support the National Metrology Institutes (NMIs) as a ‘new normal’ emerges. As a first step, the NMI ‘COVID action’ repository was implemented and two pilot studies were launched by the CCQM on the measurement of SARS-CoV-2 and SARS-CoV-2 antibodies. New ways have been developed to support the International Committee for Weights and Measures (CIPM) consultative committees on-line. For example, during 2020 a total of 70 video meetings were held for the CCQM, with similar trends for other CCs. In the following sections, we provide highlights of the work the laboratories have undertaken during 2020.
Axial forces in multistage back-to-back pumps
Authors: Kovtun O M , Tverdokhleb I B , Lugova S O , Makivskii O S , Lugovii O L 
Published: January 2021

Abstract
Since the pressure of the pumps for the oil and gas industry and feed water pumps for the thermal and nuclear power plants are increasing and at the same time the production costs need to be reduced, the demands for development of the modern multistage centrifugal pumps are increased. An enlargement of stage numbers results in an increase in the distance between the bearings and as a result the shaft deflection increases. Also, a large number of stages leads to occurrence of a significant axial force acting on the pump rotor. These issues are solved by applying a back-to-back design with a throttling bush between the groups of stages. An arrangement with such throttling bush results in an additional axial force due to the different directions of leakage in the channels (side wall gaps) between the main disks of the last impellers of both stage groups and stator elements. Therefore, the design of a throttling bush with special balancing holes was proposed. This paper examines the processes occurring in the throttling bush and compares the operating parameters for two design options-with special balancing holes, and without them.
Numerical study of the centrifugal contra rotating blade system
Authors: Kulikov A A , Ratushnyi A V , Kovaliov I A , Mandryka A S , Ignatiev A S 
Published: January 2021

Abstract
The manuscript presents the results of a numerical study of a centrifugal contra rotating blade system based on a low-speed impeller (ns = 65). They were carried out to assess the possibility of using a contra rotating blade mesh operating in conjunction with a standard centrifugal impeller as a method of intensifying the transmission of energy to a fluid. The designs of the systems under consideration and their pressure and energy characteristics are presented.
Creation a universal technique of predicting performance curves for small-sized centrifugal stages of well oil pump units
Authors: Antonenko S , Sapozhnikov S , Kondus V , Chernobrova A , Mandryka A 
Published: January 2021

Abstract
The work provided is a continuation the development of research work on the process of pumping high-viscosity liquids and is aimed at creating a universal technique of recalculating the performance curves of dynamic small-sized pumps from water to high-viscosity liquid. The practical need to develop such a technique became relevant after obtaining different results when using existing methods of predicting performance curves for hydrodynamic oil well pumps. The expediency of carrying out studies aimed at clarifying the scope of the technique for calculating the work parameters of a well oil centrifugal pump, which is being developed, is substantiated, and more thorough analysis of the structure of conversion coefficients taking into account the scale factor and flow regime in the hydraulic flow parts of the studied pumps.
The ways to increase the efficiency of the stage of low specific speed
Authors: Puzik R V , Kovalyov I O , Ratushnyi O V , Dzafarov T V , Petrenko S S 
Published: January 2021

AbstractThe paper raises the question of the possibility of reducing the energy loss of the stage of the centrifugal pump on the disk friction, the relative value of which for the stages of low and ultralow speed can be a significant proportion (up to 40%) of all losses. This is seen as one of the effective ways to increase the efficiency of such stages of centrifugal pumps.
The influence of a pipe impeller external shape on the pump parameters
Authors: Skrzypacz J , Szulc P 
Published: January 2021

Abstract
Multi-piped impellers (name proposed by the authors) represent an innovative approach to the design of rotodynamic pumps operating at the specific speed of nq<10. In such a construction the energy increase is caused by the flow of liquid through the internal impeller passages as well as by an external flow around the passages, and sensible designing of such a construction is extremely difficult. The study investigates the flow phenomena and impact of the external shape of a multi–pipe impeller on the efficiency of the process of energy transfer into liquid. The main research method involves computational fluid dynamics (CFD) simulations.
Cyclic deformation of separating tape in electromagnetic rolling pump
Authors: Prokopenko D , Shatskyi I , Vorobiov M , Ropyak L 
Published: January 2021

Abstract
The purpose of the paper is to justify a substantiation of the possibilities of trouble-free operation of de-axial pump based on the Rolamite mechanism with rolling bodies. The use of an electromagnet as a drive makes it possible to transfer the rotation into a closed space as well as abandon bearings and seals. The flexible tape allows reducing the slip friction and getting separate cameras with the possibilities to pump two substances at a time. The structure of the strain cycle of combined stretching and bending during rotation is investigated in details for the separating tape. The thickness of the tape which provides the specified durability of operation is determined.
Thrust bearing with fluid pivot
Authors: Martsynkovskyy V , Liubchenko K , Prokopenko A , Lazarenko A 
Published: January 2021

Abstract
This article describes the conditions arising from the operation of compressor and pumping equipment using traditional thrust bearings with mechanical support and leveling linkage system, which negatively affect the operation of dynamic machines in general and the thrust bearing in particular. The possibility of using the hydrodynamic pressure of an oil wedge for hydrostatic support in a thrust bearing was considered, and what positive effects could arise. The working design of a thrust bearing with fluid pivot and a calculation model are shown, allowing to take into account the hydrostatic oil film when determining the characteristics of the bearing. The results of the first tests of the bearing on the stand allow us to evaluate the performance of the design and determine further improvement and optimization of the design of the bearing with fluid pivot.
Effect of pump duty on natural frequencies and modes of its rotor vibration
Authors: Yashchenko A , Verbovyi A , Rudenko A 
Published: January 2021

Abstract
This article deals with the development of more accurate models of high-performance pump units which work in a wide range of capacities. The pump operating range can sometimes reach from 20% Qr up to 130% Qr (Qr is the rated capacity). With changes of the pump duty, pressure difference between gap seals is changing as well. This leads to changes of hydrodynamic characteristics of gap seals. In particular, changes in radial stiffness of gap seals have an effect on the rotor dynamics. The task of creating the model has been performed in Modal Analysis subprogram of the ANSYS Workbench multifunctional software complex. Developed model demonstrates a dependence between pump duty and dynamics of the rotor. The nature and extent of influence of pump feed mode on the rotor dynamics has been determined. Data charts of this dependence have been obtained.
Changes in the dynamics of the output characteristics of mechatronic systems with planetary hydraulic motors
Authors: Voloshina A , Panchenko A , Titova O , Panchenko I 
Published: January 2021

Abstract
A structural-functional diagram of a dynamic model of a mechatronic system with a planetary hydraulic motor is proposed. The initial conditions for the simulation of transients occurring in a mechatronic system with a planetary hydraulic motor are substantiated. The design parameters of the distribution system, which determine the unevenness of the output characteristics of the planetary hydraulic motor, are also substantiated. The influence of the design features of a serial and modernized hydraulic motors on the dynamic processes of the mechatronic system is investigated. It is established that fluctuations in the flow area of the distribution system of a serial hydraulic motor cause pulsations of torque on the hydraulic motor shaft and pressure in the discharge line of the mechatronic system. At the time of acceleration, significant pulsations of the flow of working fluid through the safety valve are observed, and as a result, pulsations of the flow of working fluid through the hydraulic motor. Elimination of fluctuations in the flow area of the distribution system of the upgraded hydraulic motor allows you to stabilize the values of pressure, torque and flow rate of the working fluid throughout the study of the acceleration process. Under steady-state operation, fluctuations in the area of the passage section of the distribution system do not affect the nature of the change in the shaft speed, either of the modernized or serial hydraulic motors.
Vibration resistance of HST 90 hydrostatic transmission
Authors: Ivanov M , Pereyaslavskyy O , Shargorodskiy S , Hrechko R , Mazurenko V , Holovko S 
Published: January 2021

Abstract
Hydrostatic transmissions, which are usually used in the drives of mobile machines, have recently been actively used in drives of other working bodies of machines. For example, in drives of mixers of concrete carriers, drives of working bodies of agricultural machines - straw cutters, etc. This area of use of hydrostatic transmissions is actively developing. The successful solution of this problem is prevented by the occurrence of vibrational operating modes while reducing inertial and technological loads, and in some cases leads to significant disturbances in the operation of machines. Using computer simulation of the hydrostatic transmission, the influence of the inertial and technological loads, as well as the parameters of the hydraulic system, the conditions for the occurrence of vibrational modes of its operation are analyzed. Based on the results obtained, measures have been developed to improve the design of measures and shunt valves, which allow to exclude vibrational modes of operation with a significant expansion of the range of variation of inertial and technological loads.
The results of a bench simulation of hydrostatic transmissions with advanced valves, conducted in the laboratories of PJSC Gidrosila APM (Kropyvnytskyi), confirmed the effectiveness of the proposed measures. The enterprise has begun mass production of hydrostatic transmissions of an improved design.
Long-term exposures to ambient PM1 and NO2 pollution in relation to mild cognitive impairment of male veterans in China
Authors: Chen Gongbo , Tan Jiping , Yan Lailai , Li Nan , Wang Luning , Li Na , Mai Lei , Zhao Yiming , Li Shanshan , Guo Yuming 
Published: January 2021

Abstract
Mild cognitive impairment (MCI) is an intermediate stage of cognitive decline between normal ageing and dementia or Alzheimer’s disease in the elderly. However, evidence is very limited in China for the association between air pollution and MCI. This study aims to examine the associations of long-term exposure to air pollution and MCI, using data from the Chinese Veteran Clinical Research Platform. A national investigation on mental health of veterans was conducted in 277 veteran communities in 18 cities across China. In total, 1,861 MCI cases and 3,188 controls were randomly selected using a stratified cluster sampling strategy from December 2009 to December 2011. Participants’ cognitive function was first assessed using the Mini Mental State Examination and the Montreal Cognitive Assessment in the Chinese version, and then further confirmed by clinical examination. Participants’ mean exposures to PM1 (particulate matter with aerodynamic diameter ⩽1 μm) and NO2 (nitrogen dioxide) during the 3 years before the investigation were estimated using satellite remote sensing data, meteorological variables and land use information. The association between historical exposure to air pollution and MCI was examined using Logistic regression. After controlling for individual-level and regional-level confounders, we found historical exposures to PM1 and NO2 significantly increased the risk of MCI. The odds ratios (ORs associated with per 10 µg m−3 increase in air pollution) and 95% confidence intervals for PM1 and NO2 were 1.08 (1.04, 1.13) and 1.07 (1.02, 1.13), respectively. In the multi-pollutant models, higher OR for PM1 while lower OR for NO2 were observed compared to single-pollutant models. High levels of PM1 and NO2 pollution significantly increased the risk of cognitive decline among male veterans in China. Given the causal air pollution-MCI relationship, good air quality may help to reduce the burden of mental disorders among elderly veterans in China.
Temporal correlation beyond quantum bounds in non-Hermitian PT- symmetric dynamics of a two level system
Authors: Varma Anant V , Mohanty Ipsika , Das Sourin 
Published: January 2021

Abstract
We study the dynamics of a non-Hermitian PT- symmetric Hamiltonian of a two level system (TLS) which has real eigenvalues. Within the framework of Hermitian quantum mechanics, it is known that maximal violation of Leggett–Garg inequality (LGI) is bounded by K
3 = 3/2 (Luder’s bound). We show that this absolute bound can be evaded when dynamics is governed by non-Hermitian PT- symmetric Hamiltonians with real eigenvalues. Moreover, the extent of violation can be optimized to asymptotically approach the algebraic maximum of

K

3

max

=
3

, which is otherwise observed for Hermitian Hamiltonian with infinite dimensional Hilbert space. The extreme violation of LGI is shown to be directly related to the two basic ingredients: (i) the Bloch equation for the TLS having a non-linear terms which allow for accelerated dynamics of states on the Bloch sphere exceeding all known quantum speed limits of state evolution; and (ii) quantum trajectory of states lie on a great circle (geodesic path) on the Bloch sphere at all times. We demonstrate that such extreme temporal correlation of TLS can be simulated in realistic system by embedding the TLS into a higher dimensional Hilbert space such that the composite system obeys unitary dynamics. Specifically we show that a four dimensional embedding of non-Hermitian PT- symmetric TLS is enough to host K
3 → 3 limit. We also discuss the effect of random noise on our results. Finally we conclude with a comparative study of our results with existing experimental realization of embedding.
A geometric approach to the generalized Noether theorem
Authors: Bravetti Alessandro , Garcia-Chung Angel 
Published: January 2021

Abstract
We provide a geometric extension of the generalized Noether theorem for scaling symmetries recently presented by Zhang P-M et al (2020 Eur. Phys. J. Plus
135 223). Our version of the generalized Noether theorem has several positive features: it is constructed in the most natural extension of the phase space, allowing for the symmetries to be vector fields on such manifold and for the associated invariants to be first integrals of motion; it has a direct geometrical proof, paralleling the proof of the standard phase space version of Noether’s theorem; it automatically yields an inverse Noether theorem; it applies also to a large class of dissipative systems; and finally, it allows for a much larger class of symmetries than just scaling transformations which form a Lie algebra, and are thus amenable to algebraic treatments.