bluuebunny/crossref_metadata_2025_split huggingface dataset:
Edge-illumination x-ray phase-contrast imaging
Authors: Olivo Alessandro 
Published: June 2021

Abstract
Although early demonstration dates back to the mid-sixties, x-ray phase-contrast imaging (XPCI) became hugely popular in the mid-90s, thanks to the advent of 3rd generation synchrotron facilities. Its ability to reveal object features that had so far been considered invisible to x-rays immediately suggested great potential for applications across the life and the physical sciences, and an increasing number of groups worldwide started experimenting with it. At that time, it looked like a synchrotron facility was strictly necessary to perform XPCI with some degree of efficiency—the only alternative being micro-focal sources, the limited flux of which imposed excessively long exposure times. However, new approaches emerged in the mid-00s that overcame this limitation, and allowed XPCI implementations with conventional, non-micro-focal x-ray sources. One of these approaches showing particular promise for ‘real-world’ applications is edge-illumination XPCI: this article describes the key steps in its evolution in the context of contemporary developments in XPCI research, and presents its current state-of-the-art, especially in terms of transition towards practical applications.
Electronic structure and optical properties of Na2KSb and NaK2Sb from first-principles many-body theory
Authors: Amador Raymond , Saßnick Holger-Dietrich , Cocchi Caterina 
Published: June 2021

Abstract
In the search for novel materials for vacuum electron sources, multi-alkali antimonides and in particular sodium-potassium-antimonides have been recently regarded as especially promising due to their favorable electronic and optical properties. In the framework of density-functional theory and many-body perturbation theory, we investigate the electronic structure and the dielectric response of two representative members of this family, namely Na2KSb and NaK2Sb. We find that both materials have a direct gap, which is on the order of 1.5 eV in Na2KSb and 1.0 eV in NaK2Sb. In either system, valence and conduction bands are dominated by Sb states with p- and s-character, respectively. The imaginary part of the dielectric function, computed upon explicit inclusion of electron–hole interactions to characterize the optical response of the materials, exhibits maxima starting from the near-infrared region, extending up to the visible and the ultraviolet band. With our analysis, we clarify that the lowest-energy excitations are non-excitonic in nature and that their binding energy is on the order of 100 meV. Our results confirm the potential of Na2KSb and NaK2Sb as photoemissive materials for vacuum electron sources, photomultipliers, and imaging devices.
Estimating the most probable transition time for stochastic dynamical systems
Authors: Huang Yuanfei , Chao Ying , Wei Wei , Duan Jinqiao 
Published: June 2021

Abstract
This work is devoted to the investigation of the most probable transition time between metastable states for stochastic dynamical systems with non-vanishing Brownian noise. Instead of minimizing the Onsager–Machlup action functional, we examine the maximum probability that the solution process of the system stays in a neighbourhood (or a tube) of a transition path, in order to characterize the most probable transition path. We first establish the exponential decay lower bound and a power law decay upper bound for the maximum of this probability. Based on these estimates, we further derive the lower and upper bounds for the most probable transition time, under suitable conditions. Finally, we illustrate our results in simple stochastic dynamical systems, and highlight the relation with some relevant works.
Distribution of periodic points of certain Gauss shifts with infinite invariant measure
Authors: Boca Florin P , Siskaki Maria 
Published: June 2021

Abstract
This paper investigates the periodic points of the Gauss type shifts associated to the even continued fraction (Schweiger) and to the backward continued fraction (Rényi). We show that they coincide exactly with two sets of quadratic irrationals that we call E-reduced, and respectively B-reduced. We prove that these numbers are equidistributed with respect to the (infinite) Lebesgue absolutely continuous invariant measures of the corresponding Gauss shift.
Bicycle paths, elasticae and sub-Riemannian geometry
Authors: Ardentov Andrei , Bor Gil , Le Donne Enrico , Montgomery Richard , Sachkov Yuri 
Published: June 2021

Abstract
We relate the sub-Riemannian geometry on the group of rigid motions of the plane to ‘bicycling mathematics’. We show that this geometry’s geodesics correspond to bike paths whose front tracks are either non-inflectional Euler elasticae or straight lines, and that its infinite minimizing geodesics (or ‘metric lines’) correspond to bike paths whose front tracks are either straight lines or ‘Euler’s solitons’ (also known as syntractrix or convicts’ curves).
Three-dimensional shear driven turbulence with noise at the boundary
Authors: Fan Wai-Tong Louis , Jolly Michael , Pakzad Ali 
Published: June 2021

Abstract
We consider the incompressible 3D Navier–Stokes equations subject to a shear induced by noisy movement of part of the boundary. The effect of the noise is quantified by upper bounds on the first two moments of the dissipation rate. The expected value estimate is consistent with the Kolmogorov dissipation law, recovering an upper bound as in (Doering and Constantin 1992 Phys. Rev. Lett.
69 1648) for the deterministic case. The movement of the boundary is given by an Ornstein–Uhlenbeck process; a potential for over-dissipation is noted if the Ornstein–Uhlenbeck process were replaced by the Wiener process.
Infinite DLR measures and volume-type phase transitions on countable Markov shifts
Authors: Beltrán Elmer R , Bissacot Rodrigo , Endo Eric O 
Published: June 2021

Abstract
We consider the natural definition of DLR measure in the setting of σ-finite measures on countable Markov shifts. We prove that the set of DLR measures contains the set of conformal measures associated with Walters potentials. In the BIP case, or when the potential normalizes the Ruelle’s operator, we prove that the notions of DLR and conformal coincide. On the standard renewal shift, we study the problem of describing the cases when the set of the eigenmeasures jumps from finite to infinite measures when we consider high and low temperatures, respectively. For this particular shift, we prove that there always exist finite DLR measures, and we have an expression to the critical temperature for this volume-type phase transition, which occurs only for potentials with the infinite first variation.
The time-averaged spin-Hall conductivity in two-dimensional spin–orbit coupled systems: the role of spin dynamics
Authors: Chen Tsung-Wei , Hsu Hsiu-Chuan 
Published: June 2021

Abstract
We investigate the spin-Hall conductivity (SHC) in the two-dimensional spin–orbit coupled systems by taking spin precession into account. The influence of spin precession on the spin-Hall current in the presence of disorder is investigated. Perturbation method leads to the result that the spin dynamics is composed of Larmor (periodic) and non-Larmor (non-periodic) precession. The non-Larmor component of spin is found to be the same result obtained from the Kubo formula in the short time limit. The Larmor component of spin, i.e., spin precession in the unperturbed system, was neglected in the previous studies, but it plays an important role in the linear response theory. The Larmor precession of spin should be zero after time average over several complete periods because there is no specific orientation perpendicular to the plane. By using the requirement of vanishing time-averaged Larmor precession of spin, we calculate the time-averaged non-Larmor SHC for k-cubic Rashba system by using the conventional definition of the spin current. Our result is 2.1(q/8π) which is very close to the experimental value 2.2(q/8π) by Wunderlich et al [2005 Phys. Rev. Lett.
94, 047204], where −q is the electric charge.
Casimir–Polder interaction of neutrons with metal or dielectric surfaces
Authors: Gebhart Valentin , Klatt Juliane , Cronenberg Gunther , Filter Hanno , Buhmann Stefan Yoshi 
Published: June 2021

Abstract
We predict a repulsive Casimir–Polder-type dispersion interaction between a single neutron and a metal or dielectric surface. We consider a scenario where a single neutron is subject to an external magnetic field. Due to its intrinsic magnetic moment, the neutron then forms a magnetisable two-level system which can exchange virtual photons with a nearby surface. The resulting dispersion interaction between a purely magnetic object (neutron) and a purely electric one (surface) is found to be repulsive, in contrast to the typical attractive interaction between electric objects. Its magnitude is considerably smaller than the standard atom–surface Casimir–Polder force due to the magnetic nature of the interaction and the smallness of the electron-to-neutron mass ratio. Nevertheless, we show that it can be comparable to the gravitational potential of the same surface and should be taken into consideration in future neutron interference experiments.
Few-body correlations in two-dimensional Bose and Fermi ultracold mixtures
Authors: Bougas G , Mistakidis S I , Giannakeas P , Schmelcher P 
Published: June 2021

Abstract
Few-body correlations emerging in two-dimensional harmonically trapped mixtures, are comprehensively investigated. The presence of the trap leads to the formation of atom-dimer and trap states, in addition to trimers. The Tan’s contacts of these eigenstates are studied for varying interspecies scattering lengths and mass ratio, while corresponding analytical insights are provided within the adiabatic hyperspherical formalism. The two- and three-body correlations of trimer states are substantially enhanced compared to the other eigenstates. The two-body contact of the atom-dimer and trap states features an upper bound regardless of the statistics, treated semi-classically and having an analytical prediction in the limit of large scattering lengths. Such an upper bound is absent in the three-body contact. Interestingly, by tuning the interspecies scattering length the contacts oscillate as the atom-dimer and trap states change character through the existent avoided-crossings in the energy spectra. For thermal gases, a gradual suppression of the involved two- and three-body correlations is evinced manifesting the impact of thermal effects. Moreover, spatial configurations of the distinct eigenstates ranging from localized structures to angular anisotropic patterns are captured. Our results provide valuable insights into the inherent correlation mechanisms of few-body mixtures which can be implemented in recent ultracold atom experiments and will be especially useful for probing the crossover from few- to many-atom systems.
Gamma-ray and synchrotron radiation from dark matter annihilations in ultra-faint dwarf galaxies
Authors: Bhattacharjee Pooja , Choudhury Debajyoti , Das Kasinath , Kumar Ghosh Dilip , Majumdar Pratik 
Published: June 2021

Abstract
The very large (100–1000) mass-to-light ratio applicable to the
ultra-faint dwarf galaxies (UFDs) implies a high concentration of dark
matter, thus rendering them ideal theatres for indirect signatures of
dark matter. In this paper, we consider 14 recently discovered UFDs
and study the electromagnetic radiation emanating from them over a
wide range, from gamma ray down to radio frequencies. We analyze the
Fermi-LAT data on high energy gamma rays and radio fluxes at the GMRT
and VLA to obtain upper limits on annihilation cross section
⟨σ v⟩ in a model independent way. We further
discuss the sensitivity of the Square Kilometer Array radio telescope
in probing the synchrotron radiation from the aforementioned UFDs. We
also investigate the dependences of the said upper limits on the
uncertainties in the determination of various astrophysical
parameters.
Corrigendum: The Remote Observatories of the Southeastern Association for Research in Astronomy (SARA)
Authors: Keel William C. , Oswalt Terry , Mack Peter , Henson Gary , Hillwig Todd , Batcheldor Daniel , Berrington Robert , De Pree Chris , Hartmann Dieter , Leake Martha , Licandro Javier , Murphy Brian , Webb James , Wood Matt A. 
Published: June 2021

Abstract
Bill Gray of Project Pluto brought to our attention an error of 0.03° in the listed latitude of our Kitt Peak telescope. While correcting the table where this occurred, we also take the opportunity to update the instrument properties and weather statistics of our remote telescopes.
Low-cost wireless smart device design for radiation protection and nuclear security
Authors: Mbarndouka Taamté J. , Saïdou  , Bodo B. , Kountchou Noubé M. , Folifack Signing V.R. , Yakum-Ntaw Younui S. , Hamadou Yerima A. , Iamsumang C. , Massey C. 
Published: June 2021

Abstract
This article presents the realization and implementation of
a low-cost intelligent electronic device, which detects the ambient
dose rate of Gamma and Beta ionizing radiation in
real-time. Developed according to the principle of nuclear analog
signal processing, the device uses a Geiger-Müller tube detector,
in which the electronic circuit has been readjusted to produce the
standard radiation protection signal (a slow positive logic
pulses). It also consists of low-cost components such as the
Atmega328P microcontroller board and XBee wireless modules for
environmental radiation and nuclear security monitoring. The
proposed device has several advantages, namely low energy
consumption, low-cost, easily deployable in the field (in-situ),
adapted for real-time measurements and data transmission to a remote
personal computer (PC). After calibration using Cesium (137Cs),
a comparative analysis of the data obtained from the proposed
dosimeter was carried out with those of an in-situ gamma
spectrometry chain (reference method) previously used at the same
place and under the same conditions. This analysis gave an
acceptable mean value of 64.30 nGy/h, of the proposed device,
compared to that of the gamma spectrometer, which is 50.67 nGy/h. The
prototype thus developed is simple, precise, and made for radiation
protection.
Exploring carbon footprint reduction pathways through urban lifestyle changes: a practical approach applied to Japanese cities
Authors: Koide Ryu , Kojima Satoshi , Nansai Keisuke , Lettenmeier Michael , Asakawa Kenji , Liu Chen , Murakami Shinsuke 
Published: June 2021

Abstract
Cities and urban consumers play a central role in the transition to a decarbonized society. Building on existing studies that identify the significant contributions of lifestyle changes, this study proposes a practical methodology for modeling and exploring city-specific carbon footprint reduction pathways through lifestyle changes to decarbonization. It uses an input–output approach with mixed-unit consumption data and the concept of adoption rates, which is applicable to multiple cities with widely available subnational household consumption data. This paper illustrates the use of this methodology by exploring the consumption-based mitigation pathways of 52 Japanese cities with 65 lifestyle change options covering mobility, housing, food, consumer goods, and leisure domains. The results revealed that city-specific impacts of a variety of lifestyle change options can differ by as much as a factor of five among cities, even in the urban context within the same country. Due to this city-level heterogeneity, the priority options of decarbonized lifestyles, such as among shared mobility, low-carbon diets, and longevity of consumer goods, have shifted between cities. The analysis suggests that ambitious urban lifestyle changes can potentially reduce their carbon footprints to meet the 1.5 °C target. However, due to the overlaps of mitigation potentials between multiple lifestyle change options, the necessary levels of adoption and coverage are extensive (i.e. adoption rates of 0.6–0.9). Importantly, adopting lifestyle changes with an efficiency strategy (e.g. the introduction of end-use technologies) or sufficiency strategy (e.g. behavioral changes in consumption amounts and modes) alone is not enough; the only way to succeed is through the combination of both strategies. This paper calls for a target-based exploration and identification of city-specific priorities of lifestyle change options to facilitate consumption-oriented mitigation policies and stakeholder actions to address the climate impacts of urban consumption.
Intensive field sampling increases the known extent of carbon-rich Amazonian peatland pole forests
Authors: Honorio Coronado Eurídice N , Hastie Adam , Reyna José , Flores Gerardo , Grández Julio , Lähteenoja Outi , Draper Frederick C , Åkesson Christine M , Baker Timothy R , Bhomia Rupesh K , Cole Lydia E S , Dávila Nállarett , Del Águila Jhon , Del Águila Margarita , Del Castillo Torres Dennis , Lawson Ian T , Martín Brañas Manuel , Mitchard Ed T A , Monteagudo Abel , Phillips Oliver L , Ramírez Eliseo , Ríos Marcos , Ríos Sandra , Rodriguez Lily , Roucoux Katherine H , Tagle Casapia Ximena , Vasquez Rodolfo , Wheeler Charlotte E , Montoya Mariana 
Published: June 2021

AbstractPeatland pole forest is the most carbon-dense ecosystem in Amazonia, but its spatial distribution and species composition are poorly known. To address this knowledge gap, we quantified variation in the floristic composition, peat thickness, and the amount of carbon stored above and below ground of 102 forest plots and 53 transects in northern Peruvian Amazonia. This large dataset includes 571 ground reference points of peat thickness measurements across six ecosystem types. These field data were also used to generate a new land-cover classification based on multiple satellite products using a random forest classification. Peatland pole forests are floristically distinctive and dominated by thin-stemmed woody species such asPachira nitida(Malvaceae),Platycarpum loretense(Rubiaceae), andHevea guianensis(Euphorbiaceae). In contrast, palm swamps and open peatlands are dominated byMauritia flexuosa(Arecaceae). Peatland pole forests have high peat thickness (274 ± 22 cm, mean ± 95% CI,n= 184) similar to open peatlands (282 ± 46 cm,n= 46), but greater than palm swamps (161 ± 17 cm,n= 220) and seasonally-flooded forest, terra firme, and white-sand forest where peat is rare or absent. As a result, peatland pole forest has exceptional carbon density (1,133 ± 93 Mg C ha−1). The new sites expand the known distribution of peatland pole forest by 61% within the Pastaza-Marañón Foreland basin, mainly alongside the Tigre river, to cover a total of 7540 km2in northern Peruvian Amazonia. However, only 15% of the pole forest area is within a protected area, whilst an additional 26% lies within indigenous territories. The current low levels of protection and forest degradation but high threat from road paving projects makes the Tigre river basin a priority for conservation. The long-term conservation of peatland pole forests has the potential to make a large contribution towards international commitments to mitigate climate change.
Retraction: Social and Islamic diffusion in the Nordic countries with the example of Sweden by year 2050 (IOP Conf. Ser.: Earth Environ. Sci.
302 012071)
Authors: Yu Eidemiller K , Samylovskaya E A , A Kudryavtseva R-E , Alakshin A E 
Published: June 2021

IOP Publishing Limited ("IOPP") is retracting this paper following an investigation which resulted from a reader complaint. The paper makes a number of unsubstantiated claims and, in the opinion of IOPP, lacks scientific rigour, clarity and objectivity. Although the paper was subject to peer review via the conference organisers, unfortunately these issues were not identified on this occasion. IOPP also has concerns regarding the discriminatory tone and sentiment of the paper, which are not appropriate in a scientific journal.
IOPP expresses its thanks to the readers and independent advisors who have shared their thoughts regarding this paper during the course of the investigation.
Retraction published: 24 June 2021
Modeling of the stress-strain state of reinforced concrete beams under prolonged load action
Authors: Holovata Z , Neutov S , Surianinov M 
Published: June 2021

Abstract
The paper considers the use of a layered deformation model of the stress-strain state of reinforced concrete beams experiencing transverse bending taking into account the long-term action of the load. The results of experimental studies of twelve beams made of concrete of three classes for short-term and long-term acting load are given. It has been established that long-term strength of inclined cross-sections follows the general laws of deformation and fracture of reinforced concrete. Comparison of calculation results of the proposed deformation model with experimental data has shown their satisfactory convergence. A tendency of some increase (within 10… 15%) in the long-term strength of the reinforced concrete elements under study in the inclined sections has been established experimentally.
Experimental studies of road slabs
Authors: Surianinov M , Neutov S , Korneieva I , Kirichenko D 
Published: June 2021

AbstractThe results of experimental studies of bearing capacity and cracking resistance of road slab models made of steel-fiber concrete according to the span loading scheme are presented. The bearing capacity of the models has been fixed at 27.96 kN, which is 2 times higher than the load corresponding to the beginning of cracking (14.8 kN). At the moment of bearing capacity loss, the height of compressed zone was 1 cm, which is one third of its original size. The relative strains before the first crack appeared were 0.1175×10-4 and 0.235×10-4 in the compressed and stretched zones, respectively, and similar limiting relative strains reached values of 3.715×10-4 and 9.235×10-4. The maximum crack opening width was substantially less than in the same tests of the slabs without dispersion reinforcement and was 0.3 mm, which is explained by the more ductile properties of steel fiber concrete, which prevent crack opening. The final deflection in the middle of the plate model span was 10.4 mm, which is 5.5 times greater than the deflection before cracking began (1.9 mm).
Geometry and graphics of the fractal expansion of a square and its applications
Authors: Tkach D , Sopilniak A , Yarova T , Sereda S , Kistol A 
Published: June 2021

Abstract
Geometry of the fractal expansion of simple geometric shapes, in particular the square, 5-celled cross and swastikas, is a new section of fractal geometry that correctly and clearly describes the dynamics of natural processes of growth and development of animate and inanimate cellular structures, since the iterative processes of their fractal expansion are mutually complementary and inextricably interconnected. The theoretical part of this paper requires further research, and the practical one needs for the design and engineering, and technological development of a solution to the problem for building roads with the fractal-synergetic pavement as an alternative to asphalt.