bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-pass digital filter with amplitude 1/f2 attenuation based empirical mode decomposition of vortex signal processing method
Authors: Chen Jie , Zhang Nan , Li Bin
Published: April 2021

To improve the measurement performance of the vortex flowmeter, a low-pass digital filter with amplitude 1/f2 attenuation based empirical mode decomposition (EMD) of the vortex signal processing method is proposed. According to the amplitude–frequency characteristic of the vortex signal, a second-order low-pass digital filter is used for vortex signal preprocessing. Due to the amplitude 1/f2 attenuation characteristic of the second-order low-pass digital filter, the high frequency noise can be filtered out and the amplitude of the vortex signal can be normalized. Referring to the result of normalization, an amplitude threshold is set, which will be used as the criterion for selecting the effective vortex signal component after EMD. The simulation experiment and real flow anti-interference experiment are conducted. The experimental results show that the proposed method can adaptively select the vortex signal component and has advantages over the traditional methods based on EMD in terms of frequency measurement accuracy, operational efficiency, and anti-interference performance.
Reweighting non-equilibrium steady-state dynamics along collective variables
Authors: Bause Marius , Bereau Tristan
Published: April 2021

Computer simulations generate microscopic trajectories of complex systems at a single thermodynamic state point. We recently introduced a Maximum Caliber (MaxCal) approach for dynamical reweighting. Our approach mapped these trajectories to a Markovian description on the configurational coordinates and reweighted path probabilities as a function of external forces. Trajectory probabilities can be dynamically reweighted both from and to equilibrium or non-equilibrium steady states. As the system’s dimensionality increases, an exhaustive description of the microtrajectories becomes prohibitive—even with a Markovian assumption. Instead, we reduce the dimensionality of the configurational space to collective variables (CVs). Going from configurational to CV space, we define local entropy productions derived from configurationally averaged mean forces. The entropy production is shown to be a suitable constraint on MaxCal for non-equilibrium steady states expressed as a function of CVs. We test the reweighting procedure on two systems: a particle subject to a two-dimensional potential and a coarse-grained peptide. Our CV-based MaxCal approach expands dynamical reweighting to larger systems, for both static and dynamical properties, and across a large range of driving forces.
MHD mode identification by higher order singular value decomposition of C-2W Mirnov probe data
Authors: Tobin M. , Roche T. , Matsumoto T. ,   TAE Team
Published: April 2021

The C-2W device (also known as “Norman”) at TAE Technologies has proven successful at generating stable, long-lived field-reversed configuration (FRC) plasmas with record temperatures. The largest Mirnov probe array in C-2W measures three components of the magnetic field just inside the vessel wall at 64 locations distributed approximately evenly in the cylindrical vessel’s azimuthal and axial dimensions. This nearly rectangular array of probes creates a unique opportunity to apply higher order singular value decomposition (HOSVD) to efficiently analyze the external magnetic field data for the purposes of reconstructing the magnetohydrodynamic mode structures in the FRC. In the first application of this method for this purpose, HOSVD is shown to quickly and effectively detect and separate toroidal modes while indicating longitudinal dependence of mode phases and amplitudes, enhancing the coherence and utility of the vast quantity of data produced by this array. Analysis of the data from the entire array at once via HOSVD proves not only computationally more efficient than methods that separately analyze groups of probes at different axial locations but also leads to improved mode resolution at axial locations where these modes are weaker.
Apparatus for skidding sensitivity testing of energetic materials
Authors: Hewitt A. T. , Lee R. J. , Watkins S. , Brinkman J. , Stephens J. C. , Dickens James C. , Neuber Andreas A.
Published: April 2021

A remote-operated apparatus for testing the detonation sensitivity of energetic materials is detailed. Using an air ram and rotating disk, the normal force and transverse velocity of the impact plane are controlled independently, enabling the exploration of varying impact conditions over a wide parameter space. A microcontroller local to the apparatus is used to automate apparatus operation and ensure temporal alignment of the impacting ram head with the rotating disk. Calculation of the firing parameters and issuing of operational commands are handled by a remote computer and relayed to the local microcontroller for execution at the hardware level. Impact forces are taken from fast strain measurements obtained from gauges incorporated into the ram head. Infrared imaging of explosive samples provides insight into the peak thermal temperatures experienced at the sample surface during the impact event.
Spin contamination in MP2 and CC2, a surprising issue
Authors: Kitsaras Marios-Petros , Stopkowicz Stella
Published: April 2021

When calculating the spin multiplicity at either the second-order Møller-Plesset (MP2) or the iterative second-order approximate coupled-cluster singles and doubles (CC2) levels of theory using the same strategy for the calculation of the expectation value as in regular CC theory together with the usual definitions of the MP2 and CC2 density matrices, artificial spin contamination occurs in closed-shell molecules. Non-intuitively, for open-shell systems, results at the MP2 or CC2 levels of theory based on this procedure even suggest stronger contamination at the correlated level than for the Hartree–Fock reference, although treatment of electron correlation should lower spin contamination. In this Communication, the reasons behind this inconsistency are investigated and a solution is proposed, which removes spin contamination for closed-shell molecules and leads to physically meaningful results for open-shell cases. Additionally, we show that CC2 significantly outperforms MP2 in describing systems with a strongly spin-contaminated reference with a performance similar to that of full coupled-cluster with singles and doubles substitutions (CCSD).
Processing and reprocessing liquid crystal elastomer
actuators
Authors: Mistry Devesh , Traugutt Nicholas A. , Yu Kai , Yakacki Christopher M.
Published: April 2021

Liquid crystal elastomers (LCEs) have long been celebrated for their exceptional shape actuation and mechanical properties. For much of the last half century, a major focus for the field has been the development of LCE chemistries and how to process the so-called “monodomain” configurations. This foundation work has now led to a plethora of materials and processes that are enabling the demonstration of devices that are close to real-world applicability as responsive and reprocessable actuators. In this Perspective, we review and discuss the key recent developments in the processing of actuating LCE devices. We consider how processing has been used to increase the practicality of electrical, thermal, and photo stimulation of LCE shape actuation; how dynamic chemistries are enhancing the functionality and sustainability of LCE devices; and how new additive manufacturing technologies are overcoming the processing barriers that once confined LCE actuators to thin film devices. In our outlook, we consider all these factors together and discuss what developments over the coming years will finally lead to the realization of commercial shape actuating LCE technologies.
Calculation of self-diffusion coefficients in supercritical carbon dioxide using mean force kinetic theory
Authors: Scheiner Brett , Yoon Tae Jun
Published: April 2021

This paper presents an application of mean force kinetic theory (MFT) to the calculation of the self-diffusivity of CO2 in the supercritical fluid regime. Two modifications to the typical application of MFT are employed to allow its application to a system of molecular species. The first is the assumption that the inter-particle potential of mean force can be obtained from the molecule center-of-mass pair correlation function, which in the case of CO2 is the C–C pair correlation function. The second is a new definition of the Enskog factor that describes the effect of correlations at the surface of the collision volume. The new definition retains the physical picture that this quantity represents a local density increase, resulting from particle correlations, relative to that in the zero density homogeneous fluid limit. These calculations are facilitated by the calculation of pair correlation functions from molecular dynamics (MD) simulations using the FEPM2 molecular CO2 model. The self-diffusivity calculated from theory is in good agreement with that from MD simulations up to and slightly beyond the density at the location of the Frenkel line. The calculation is compared with and is found to perform similarly well to other commonly used models but has a greater potential for application to systems of mixed species and to systems of particles with long range interatomic potentials due to electrostatic interactions.
Solid–liquid coexistence of neon, argon, krypton, and xenon studied by simulations
Authors: Singh Aditya N. , Dyre Jeppe C. , Pedersen Ulf R.
Published: April 2021

The noble elements constitute the simplest group of atoms. At low temperatures or high pressures, they freeze into the face-centered cubic (fcc) crystal structure (except helium). This paper investigates neon, argon, krypton, and xenon by molecular dynamics using the simplified atomic potentials recently proposed by Deiters and Sadus [J. Chem. Phys. 150, 134504 (2019)], which are parameterized using data from accurate ab initio quantum-mechanical calculations by the coupled-cluster approach at the single-double-triple level. We compute the fcc freezing lines and find good agreement with the empirical values. At low pressures, predictions are improved by including many-body corrections. Hidden scale invariance of the potential-energy function is established by showing that mean-squared displacement and the static structure factor are invariant along the lines of constant excess entropy (isomorphs). The isomorph theory of melting [Pedersen et al., Nat. Commun. 7, 12386 (2016)] is used to predict from simulations at a single state point the freezing line’s shape, the entropy of melting, and the Lindemann parameter of the crystal at melting. Finally, our results suggest that the body-centered cubic crystal is the thermodynamically stable phase at high pressures.
How to create giant Dzyaloshinskii–Moriya interactions? Analytical derivation and ab initio calculations on model dicopper(II) complexes
Authors: Bouammali Mohammed-Amine , Suaud Nicolas , Martins Cyril , Maurice Rémi , Guihéry Nathalie
Published: April 2021

This paper is a theoretical “proof of concept” on how the on-site first-order spin–orbit coupling (SOC) can generate giant Dzyaloshinskii–Moriya interactions in binuclear transition metal complexes. This effective interaction plays a key role in strongly correlated materials, skyrmions, multiferroics, and molecular magnets of promising use in quantum information science and computing. Despite this, its determination from both theory and experiment is still in its infancy and existing systems usually exhibit very tiny magnitudes. We derive analytical formulas that perfectly reproduce both the nature and the magnitude of the Dzyaloshinskii–Moriya interaction calculated using state-of-the-art ab initio calculations performed on model bicopper(II) complexes. We also study which geometrical structures/ligand-field forces would enable one to control the magnitude and the orientation of the Dzyaloshinskii–Moriya vector in order to guide future synthesis of molecules or materials. This article provides an understanding of its microscopic origin and proposes recipes to increase its magnitude. We show that (i) the on-site mixings of 3d orbitals rule the orientation and magnitude of this interaction, (ii) increased values can be obtained by choosing more covalent complexes, and (iii) huge values (∼1000 cm−1) and controlled orientations could be reached by approaching structures exhibiting on-site first-order SOC, i.e., displaying an “unquenched orbital momentum.”
Supersonic needle-jet generation with single cavitation bubbles
Authors: Reuter Fabian , Ohl Claus-Dieter
Published: April 2021

Collapsing cavitation bubbles produce intense microscopic flows. Here, in an aqueous environment, we seed single laser-induced bubbles (diameter about one millimeter) in proximity to a solid surface, in a regime that has not been well explored before in order to generate a “needle jet.” The needle jet propagates at supersonic speed through the gas phase toward the solid. It reaches average velocities of more than 850 ms−1 and thus is an order of magnitude faster than the regular jets that have frequently been observed in cavitation bubbles. The dynamics leading to the needle jet formation are studied with high speed imaging at five million frames per second with femtosecond illumination. This highly repeatable, localized flow phenomenon may be exploited for injection purposes or material processing, and it is expected to generate significantly larger water hammer pressures and may also play a role in cavitation erosion and peening.
Drag reduction of a blunt body through reconfiguration of rear flexible plates
Authors: García-Baena C. , Jiménez-González J. I. , Martínez-Bazán C.
Published: April 2021

We investigate the quasi-static reconfiguration of rear parallel flexible plates on the drag coefficient of a blunt body. The drag coefficient, plates deformation, and main features of the turbulent wake are characterized experimentally in a towing tank. It is found that increasing the flexibility of plates leads to an important drag reduction, induced by the progressive streamlining of the trailing edge due to plates deformation. The study of the Vogel exponent is adopted here to evaluate the limit on the potential drag reduction at large values of the Cauchy number, which is shown to be mainly caused by the growth in the vibrating amplitude response of plates. The plates deformation is analyzed by means of image processing, showing that their shapes mainly follow the first modal form of a cantilever beam deflection, although a slight concavity develops toward the plates tip for large Cauchy numbers. To further analyze this process, the empirical flow loading along the plates is estimated by a modified beam theory assuming a distributed load given by a power law. The experimental fitting shows that for large flexibility, the load diminishes at the rear tip. Besides, the progressive deformation of plates is shown to weaken the shedding of vortices and reduce the size of the recirculation bubble. Finally, an affine direct relationship between recirculation bubble aspect ratio and drag coefficient has been proposed in order to quantify the linkage between near wake modifications and hydrodynamic improvement provided by the trailing edge streamlining.
Impact of Cu-deficient p-n heterointerface in CuGaSe2 photovoltaic devices
Authors: Ishizuka Shogo
Published: April 2021

It is expected that Cu-deficient phases of chalcopyrite CuGaSe2 (CGS), such as CuGa3Se5, will be used widely as functional materials in energy conversion devices. In this study, the effect of a Cu-deficient CGS layer (CDL) at the p-CGS/n-CdS interface was investigated. The presence of the CDL was found to have a significant effect on increasing the open-circuit voltage (Voc) of CGS photovoltaic devices. This result is contrary to the results obtained for CuInSe2 (CIS) and Cu(In,Ga)Se2 (CIGS) devices, which showed a decrease in Voc with the increasing CDL thickness. It was also found that the use of a thicker n-CdS layer is effective in increasing the short-circuit current density (Jsc) and Voc for CGS devices fabricated with a thick CDL. These trends are unique to CGS devices and are, thus, expected to offer unique and specific routes for improving wide-gap chalcopyrite photovoltaic device performance, in addition to offering a conventional strategy for adjusting the conduction band alignment of the p-CGS/n-buffer interface with proper n-buffer materials.
Medieval weather prediction
Authors: Lawrence-Mathers Anne
Published: April 2021

Meteorological practices that developed in the first millennium did not die in the Middle Ages but were radically improved with an international science of weather forecasting.
Shifts in the seagrass leaf microbiome associated with wasting disease in
Authors: Hurtado-McCormick V. , Krix D. , Tschitschko B. , Siboni N. , Ralph P. J. , Seymour J. R.
Published: April 2021

Seagrass wasting disease (SWD), an infection believed to be caused by Labyrinthula zosterae, has been linked to seagrass declines in several places around the world. However, there is uncertainty about the mechanisms of disease and the potential involvement of opportunistic colonising microorganisms. Using 16S rRNA gene amplicon sequencing, we compared the microbiome of SWD lesions in leaves of Zostera muelleri with communities in adjacent asymptomatic tissues and healthy leaves. The microbiome of healthy leaf tissues was dominated by Pseudomonas and Burkholderia, whereas the most predominant taxa within adjacent tissues were Pseudomonas and Rubidimonas. Members of the Saprospiraceae, potential macroalgal pathogens, were over-represented within SWD lesions. These pronounced changes in microbiome structure were also apparent when we examined the core microbiome of different tissue types. Although the core microbiome associated with healthy leaves included three operational taxonomic units (OTUs) classified as Burkholderia, Cryomorphaceae and the SAR11 clade, a single core OTU from the Arenicella was found within adjacent tissues. Burkholderia are diazotrophic microorganisms and may play an important role in seagrass nitrogen acquisition. In contrast, some members of the Arenicella have been implicated in necrotic disease in other benthic animals. Moreover, microbiome structure was maintained across sites within healthy tissues, but not within SWD lesions or the tissues immediately adjacent to lesions. Predicted functional profiles revealed increased photoautotrophic functions in SWD tissues relative to healthy leaves, but no increase in pathogenicity or virulence. Notably, we demonstrated the presence of L. zosterae in SWD lesions by polymerase chain reaction, but only in one of the two sampled locations, which indicates that other microbiological factors may be involved in the initiation or development of SWD-like symptoms. This study suggests that the dynamics of the seagrass microbiome should be considered within the diagnosis and management of SWD.
Bacterial-induced pH shifts link individual cell physiology to macroscale collective behavior
Authors: Dharanishanthi Veeramuthu , Orgad Amit , Rotem Neta , Hagai Efrat , Kerstnus-Banchik Jeny , Ben-Ari Julius , Harig Tim , Ravella Srinivasa Rao , Schulz Stefan , Helman Yael
Published: April 2021

Significance

Individual cells within a community often need to respond to changing environmental conditions at the population level. Accordingly, bacteria have evolved a large array of regulatory mechanisms that enable them to quickly reprogram behavior in a coordinated manner. Unraveling these mechanisms provides valuable information regarding collective behavior in the bacterial world. Herein, we show that by modulating the environmental pH levels, bacterial colonies reflect the nutritional status of the environment and accordingly regulate a collective form of surface motility. We further show that in mixed populations, neighboring bacterial species can change the outcome of such regulation through pH modification and thus affect the community’s spatial organization.
Hidden order and multipolar exchange striction in a correlated
f
-electron system
Authors: Pourovskii Leonid V. , Khmelevskyi Sergii
Published: April 2021

Significance

Second-order phase transitions in solids occur due to spontaneous symmetry breaking with an order parameter continuously emerging from the disordered high-temperature phase. In some materials, the phase transitions are clearly detected in thermodynamic functions (e.g., specific heat), but the microscopic order parameters remain “hidden” from researchers, in some cases for decades. Here, we show how such hidden-order parameters can be unambiguously identified and the corresponding ordered phase fully described using a first-principles many-body linear response theory. Considering the canonical “hidden-order” system neptunium dioxide, we also identify an unconventional mechanism of spontaneous multipolar exchange striction that induces an anomalous volume contraction of the hidden-order phase in NpO
2
.
Erionota thrax (banana skipper).
Authors: Cock Matthew
Published: April 2021

The pest status of E. thrax was described early in the 20th Century (Dammerman, 1919, 1929). According to Corbet and Pendlebury (1992) the very similar Erionota torus has the same life history, and some of the records in the literature may relate to this species. For example, Zhang (1994) mentioned Hong Kong and the Chinese province of Guangdong, where only E. torus is known (Hill et al., 1978; Johnston and Johnston, 1980).
Setaria parviflora (knotroot foxtail).
Authors: Buddenhagen Chris
Published: April 2021

S. parviflora is a variable, self-compatible, rhizomatous, C4 plant with a short lived seed bank, commonly regarded as an agricultural weed both in its native and introduced range (Rabinowitz and Rapp, 1981; Pensiero, 1999; Mollard et al., 2007; Mollard and Insausti, 2011; Randall, 2012). It often colonizes cultivated and disturbed soils or waste places including seasonally wet sites and salt marshes (Hubbard, 1954; Leithead et al., 1971; Pott and Pott, 2004; Edgar and Connor, 2010). It can contaminate wool (Ryves et al., 1996), seed crops, especially those of grasses such as dryland rice, lawn seed and Bahia grass (Paspalum notatum) (Silveira Filho and Aquino, 1983; Wehtje et al., 2008; Seed Regulatory and Testing Branch, 2011) and degrade and dominate sod and pastures (including alfalfa), lowering hay quality, a problem because it can cause lesions in livestock (Murphy et al., 1992; Arregui et al., 2001; Muller and Via, 2012). Land infested with it might be considered to have lower value because of poor pasture. It is regarded as a member of the alien flora of Chile (Ugarte et al., 2011).
Bruchus pisorum (pea weevil).
Authors: Wale Melaku
Published: April 2021

The pea weevil is a small insect (up to 5 mm long) with good flight possibilities. The adults may fly up to 5 km in search of pea flowers. The larvae develop within a single pea seed; the pupae and newly emerged adults also remain there, so the pest is easily spread all over the world in seed (grain) trade. This is the reason why the pest can be found everywhere that pea is cultivated. It may be invasive in tropical, subtropical and warmer parts of temperate zones. It only has one generation per year, but is a prevalent pest on pea in many countries, causing considerable damage. Infestation by the pest causes economic losses, partly due to the direct loss of seed contents consumed by the pest and partly due to the fact that weevil-damaged seed has a lower germination rate and fetches a lower unit price.
Castanea mollissima (hairy chestnut).
Authors: Praciak Andrew
Published: April 2021

C. mollissima has been cultivated for its nuts by the Chinese for at least 2500 years. The tree grows under a wide variety of environmental conditions, is drought- and flood-tolerant, and is very resistant to chestnut blight (Cryphonectria parasitica), which is a serious disease of Castanea species. In recent years, Chinese chestnut has been planted on a large scale in rural areas of China and on a smaller scale in the USA (Wallace, 1995), where Warmund (2011) considered it to have potential as a niche crop in the central states. In 1995, approximately 245,000 t of nuts were produced in China, of which 51,000 t came from Shandong Province and 29,000 t from Hubei Province. Overall, mean nut production in China increased from 225 kg/ha during the 1980s to 335 kg/ha in the 1990s, with yields of up to 1500 kg/ha being recorded widely (Zheng, 1985; Gao, 1997).
Enabling covariational reasoning in Einstein’s formula for photoelectric effect
Authors: Sokolowski Andrzej
Published: April 2021

Research has identified several students’ misinterpretations of the principles of the photoelectric effect (PE). Students cannot interpret the formula using the graph’s context despite the linear dependence inherited in it. Many studies pointed out that the graphical representation of kinetic energy of the ejected electrons versus frequency of incident photons is unclear when a blend of mathematical and scientific reasoning is applied. While research suggests various ways to help improve the understanding, little attention is given to the algebraic structure of the equation

K

Max

=
h
f
−

W

o

and its corresponding graphical representation. Detailed scrutiny revealed that some phases of the PE’s algebraic expression do not support its visual representation. This paper suggests a more consistent alignment of the rules of mathematics with the PE process. This suggestion emerged as an alternative algebraic representation of the law of conservation of energy in the form of a piecewise linear function. It is hypothesized that such covariational relation between photons’ frequency and the ejected electrons’ kinetic energy is more consistent with observable phenomena behaviour and students’ mathematics knowledge. While formulating the law of conservation of energy, a physics simulation, The Photoelectric Effect (http://phet.colorado.edu), was used. The process of mathematical modelling of the PE that concluded with a covariational relation of the kinetic energy of ejected electrons was delivered to a group of 20 (N = 20) high school physics students. A didactical outline of the instructional unit is included.
From sleep medicine to medicine during sleep–a clinical perspective
Authors: Bar Nitai , Sobel Jonathan A , Penzel Thomas , Shamay Yosi , Behar Joachim A
Published: April 2021

Objective. In this perspective paper, we aim to highlight the potential of sleep as an auspicious time for diagnosis, management and therapy of non-sleep-specific pathologies. Approach. Sleep has a profound influence on the physiology of body systems and biological processes. Molecular studies have shown circadian-regulated shifts in protein expression patterns across human tissues, further emphasizing the unique functional, behavioral and pharmacokinetic landscape of sleep. Thus, many pathological processes are also expected to exhibit sleep-specific manifestations. Modern advances in biosensor technologies have enabled remote, non-invasive recording of a growing number of physiologic parameters and biomarkers promoting the detection and study of such processes. Main results. Here, we introduce key clinical studies in selected medical fields, which leveraged novel technologies and the advantageous period of sleep to diagnose, monitor and treat pathologies. Studies demonstrate that sleep is an ideal time frame for the collection of long and clean physiological time series data which can then be analyzed using data-driven algorithms such as deep learning. Significance.This new paradigm proposes opportunities to further harness modern technologies to explore human health and disease during sleep and to advance the development of novel clinical applications – from sleep medicine to medicine during sleep.
A comparative study of internal kink stability in EU DEMO designs with negative and positive triangularity
Authors: Zhou Lina , Liu Yueqiang , Siccinio Mattia , Fable Emiliano , Wu Tingting , Kurki-Suonio Taina , Varje Jari , Liu Deyong
Published: April 2021

Internal kink (IK) instability is investigated for European demonstration fusion reactor (EU DEMO) plasmas in both negative triangularity (NT) and positive triangularity (PT) configurations. For NT plasmas, the IK becomes more unstable as an ideal conformal wall moves away from the plasma boundary, with the mode growth rate saturating at the wall radial location of about

b

/

a

=
1.5

, where a is the plasma minor radius and b the wall radial location. The plasma resistivity destabilizes the IK mode. The effect of sub-sonic toroidal plasma flow is sufficiently weak and can thus be ignored for these EU DEMO equilibria. These results are consistent with those for PT plasmas, albeit with larger mode growth rate in the NT configuration. Both perturbative and self-consistent magneto-hydrodynamic (MHD)-kinetic hybrid calculations predict (partial) stabilization of the IK modes in both NT and PT configurations, with inclusion of various kinetic contributions. Precessional drift motion of trapped fusion-born alphas in EU DEMO produces weak stabilization to the IK mode. Stronger stabilization occurs with the toroidal precession of trapped thermal particles (ions and electrons) and the bounce-transit motion of thermal ions. The stabilization is similar between the NT and PT configurations, due to the similarity of the mode eigenfunction (occupying a nearly circular region in the plasma core) despite the sign difference in the triangularity. The non-perturbative MHD-kinetic hybrid model predicts much less stabilization of the mode than the perturbative model, primarily due to the self-consistent determination of the mode eigenvalue in the former. Generally, no significant difference in the IK mode stability is found between the NT and PT plasmas in EU DEMO.
Anisotropies in the arrival directions of ultra-high-energy cosmic rays measured at the Pierre Auger Observatory
Authors: Bister Teresa
Published: April 2021

The search for anisotropies in the arrival directions of cosmic rays of the highest energies is essential in the ongoing effort to identify their sources. After more than 15 years of operation, the exposure of the Pierre Auger Observatory exceeds 100,000 km2 sr yr and several important scientific findings regarding anisotropy studies on various angular scales have been reported. In the large-scale regime, a dipolar modulation above an energy threshold of 8 EeV was discovered with a significance exceeding the 5σ confidence level. The dipole exhibits an amplitude of

6.6

−
0.8

+
1.2

%

and its maximum points 125° away from the Galactic center, thus providing observational evidence for an extragalactic origin of the highest-energy cosmic rays. The analysis of the equatorial component was extended to lower energies down to 0.03 EeV where the dipole phase changes towards the Galactic center. At the highest energies, searches for small- and intermediate-scale anisotropies were performed. A model-independent search for overdensities as well as a correlation study with the direction of the nearby radio galaxy Centaurus A was conducted. Additionally, comparisons to four catalogs of candidate sources were performed using a maximum likelihood analysis. The comparison of the cosmic-ray arrival directions to a sample of starburst galaxies results in the highest post-trial significance, which lately surpassed the 4.5σ confidence level above 38 EeV. This review provides an overview of the Pierre Auger Collaboration’s most important findings concerning anisotropy in the arrival directions of ultra-high-energy cosmic rays.
Quintessential inflation in Palatini gravity
Authors: Verner Sarunas
Published: April 2021

We study a model of quintessential inflation in the context
of Palatini gravity. As a representative example, we consider the
Peebles-Vilenkin model of quintessential inflation with a small
non-minimal coupling to gravity, which is consistent with the most
recent Planck measurements. At the end of inflation, the inflaton
field passes through a tachyonic region and it leads to explosive
particle production through the tachyonic preheating process. After
preheating, the Universe becomes dominated by the kinetic energy of
the inflaton and enters a period of kination. Eventually, the total
energy density of the Universe becomes dominated by radiation,
resulting in reheating. We find that the model predicts the
reheating temperature values TRH∼𝒪(103 -
108) GeV, which is significantly above the temperature of
Big Bang Nucleosynthesis. Following reheating, the inflaton field
rolls down the quintessence potential until it freezes. Since the
quintessence remains frozen until the present day, the residual
potential energy density at this field value explains the observed
dark energy density.
Neutrino scattering off a black hole surrounded by a magnetized accretion disk
Authors: Dvornikov Maxim
Published: April 2021

We study the neutrino scattering off a rotating black hole
with a realistic accretion disk permeated by an intrinsic magnetic
field. Neutrino trajectories in curved spacetime as well as the
particle spin evolution in dense matter of an accretion disk and in
the magnetic field are accounted for exactly. We obtain the fluxes
of outgoing ultrarelativistic neutrinos taking into account the
change of the neutrino polarization owing to spin
oscillations. Using the conservative value of the neutrino magnetic
moment and realistic radial distributions of the matter density and
the magnetic field strength, we get that these fluxes are reduced by
several percent compared to the case when no spin oscillations are
accounted for. In some situations, there are spikes in the neutrino
fluxes because of the neutrino interaction with the rotating plasma
of an accretion disk. Taking into account the uncertainties in the
astrophysical neutrino fluxes, the predicted effects turn out to be
quite small to be observed with the current neutrino telescopes.
Aluminium zinc oxide as a saturable absorber for passively Q-switched and mode-locked erbium-doped fiber laser
Authors: Nizamani B , Jafry A A A , Salam S , Fizza G , Soboh R S M , Abdul Khudus M I M , Hanafi E , Yasin M , Harun S W
Published: April 2021

Transparent conductive oxides (TCOs) are widely integrated in the field of optoelectronics since they are optically transparent and electrically conductive at the same time. Indium tin oxide (ITO) is a well-developed TCO, but due to its high cost, aluminum zinc oxide (AZO) is now emerging as a promising low-cost replacement for ITO. This work reports on AZO thin film prepared with polyvinyl alcohol (PVA) as a host material. The AZO–PVA thin film was incorporated into an erbium-doped fiber laser (EDFL) as a saturable absorber for the first time. Both Q-switched and nanosecond pulse mode-locked operation were experimentally achieved. The Q-switched EDFL operated at the center wavelength of 1559.6 nm, which had the shortest pulse width of 2.2 µs, the maximum repetition rate of 86 kHz and the highest pulse energy of 47.3 nJ. The mode-locked was achieved at the center wavelength of 1560.4 nm.
Nonlocal advantage of quantum coherence of coupled qubits in thermal and dephasing reservoirs
Authors: Xie Yu-Xia
Published: April 2021

We investigate the nonlocal advantage of quantum coherence (NAQC) for two qubits coupled via the Heisenberg interaction and embedded in their respective thermal and dephasing reservoirs. Unlike the case of two uncoupled qubits, we showed that in the presence of the Heisenberg interaction, the decay rate of the NAQC can be reduced and the strength of the NAQC can be enhanced for certain initial states. Moreover, the Heisenberg interaction of two spins can induce generation of NAQC from the initial product states, and the generated NAQC approaches asymptotically to its maximum with the increasing anisotropy of the Heisenberg interaction.
Effects of centrality fluctuation and deuteron formation on the proton number cumulant in Au+Au collisions at

= 3 GeV from the JAM model *
Authors: Chatterjee Arghya , Zhang Yu , Liu Hui , Wang Ruiqin , He Shu , Luo Xiaofeng
Published: April 2021

We studied the effects of centrality fluctuation and deuteron formation on the cumulant (

) and correlation functions (

) of protons up to the sixth order in the most central (

< 3 fm) Au+Au collisions at

= 3 GeV in a microscopic transport model (JAM). The results are presented as a function of rapidity acceptance within the transverse momentum 0.4 < p T < 2 GeV/ c. We compared the results obtained by the centrality bin width correction (CBWC) using charged reference particle multiplicities with the CBWC using impact parameter bins. It was found that, at low energies, the centrality resolution for determining the collision centrality using charged particle multiplicities is not sufficient to reduce the initial volume fluctuation effect for higher-order cumulant analysis. New methods need to be developed to classify events with high centrality resolution for heavy-ion collisions at low energies. Finally, we observed that the formation of deuterons suppresses the higher-order cumulants and correlation functions of protons and found it to be similar to the efficiency effect. This work can serve as a noncritical baseline for the QCD critical point search in the high baryon density region.
Bayesian inference on isospin splitting of nucleon effective mass from giant resonances in 208Pb *
Authors: Zhang Zhen , Feng Xue-Bin , Chen Lie-Wen
Published: April 2021

From a Bayesian analysis of the electric dipole polarizability, the constrained energy of isovector giant dipole resonance, the peak energy of isocalar giant quadrupole resonance, and the constrained energy of isocalar giant monopole resonance in 208Pb, we extract the isoscalar and isovector effective masses in nuclear matter at saturation density

as

and

, respectively, at 90% confidence level. The constraints obtained on

and

lead to a positive isospin splitting of nucleon effective mass in asymmetric nuclear matter of isospin asymmetry

at

as

. In addition, the symmetry energy at the subsaturation density

is determined to be

MeV at 90% confidence level.
Type-I ELM power loads on the closed outer divertor targets in the HL-2A tokamak
Authors: Gao J.M. , Cai L.Z. , Zou X.L. , Eich T. , Adamek J. , Cao C.Z , Huang Z.H. , Ji X.Q. , Jiang M. , Liu L. , Lu J. , Liu Y. , Shi Z.B. , Thornton A.J. , Wu N. , Xiao G.L. , Xu M. , Yan L.W. , Yu L.M. , Yu D.L. , Yang Q.W. , Zhong W.L.
Published: April 2021

The HL-2A tokamak has a very closed divertor geometry, and a new infrared camera has been installed for high resolution studies of edge-localized mode (ELM) heat load onto the outer divertor targets. The characteristics of power deposition patterns on the lower outer divertor target plates during ELMs are systematically analysed with infrared thermography. The ELM energy loss is in the range of 3%–8% of the total plasma stored energy. The peak heat flux on the outer divertor targets during ELMs currently achieved in HL-2A is about 1.5–3.2 MW m−2, the wetted area is about 0.5–0.7 m2, and the corresponding integrated power decay length at the midplane is about 25–40 mm. The rise time of the ELM power deposition is in the range of about 100 μs to 400 μs, and the decay time is typically 1.5 to 4 times longer than the corresponding rise time. Convective transport along open field lines during the ELM rise phase from the midplane towards the divertor targets is implied due to the correlation of parallel transport time in the scrape-off layer (SOL) and ELM power rise time. The peak ELM energy fluence is compared with those predicted by models and with experimental data from JET, ASDEX Upgrade, MAST, and COMPASS. The results, as a whole, show a good agreement.
Detection of low-magnetic fields by rubidium (87Rb) vapor cell
Authors: Maciel M. J. , Silva M. F. , Pimenta S. , Correia J. H.
Published: April 2021

This paper describes the work carried out to assess the use of a quartz reference rubidium (87Rb) vapor cell for non-invasively magnetoencephalography, avoiding cryogenically cooled sensors as the Superconducting Quantum Interference Devices (SQUIDs). An experimental setup based on a cylindrical glass vapor cell of 87Rb (l = 75 mm, d =19 mm) was developed. The 87Rb cell was heated to around 75°C and it was optically pumped with polarized light (range 750-850 nm), tuned to the D1 transition of rubidium, for spin-polarization of the atoms, and the intensity of the light transmitted through the cell was detected using a photodiode. Without magnetic field, the photodiode current is maximized but when a small transverse magnetic field is present a measurable drop in light transmission occurs. A Magnetic Shielded Box (MSB) made by a nickel-iron ferromagnetic alloy, was used for nulling background magnetic fields and the transmittance light versus transverse magnetic field intensity (100-1000 nT) was measured.
Enhancement of unsteady frequency responses of electro-thermal resonance MEMS cantilever sensors
Authors: Setiono Andi , Nyang’au Wilson Ombati , Fahrbach Michael , Xu Jiushuai , Bertke Maik , Wasisto Hutomo Suryo , Peiner Erwin
Published: April 2021

Unsteady frequency response of in-plane electro-thermal MEMS-based cantilever sensors can cause up-/down-shifting of the resonance phase, which becomes an inhibitive factor in resonance locking using a phase-locked loop setup. Moreover, the inconsistency of resonance phase during real-time measurement potentially causes inaccuracy in resonant-frequency locking. In this work, reference parameters are differentially subtracted from the sensor output signals to enhance the characteristic of frequency response. As a calculation result, a constant resonance phase can be successfully achieved by adjusting the reference parameters close to the sensor baseline, both in sensor amplitude and phase.
Angular distribution measurement of atoms evaporated from a resistive oven applied to ion beam production
Authors: Leduc A. , Thuillier T. , Maunoury L. , Bajeat O.
Published: April 2021

A low temperature oven has been developed to produce calcium
beam with Electron Cyclotron Resonance Ion Source (ECRIS). The atom flux from the oven has been studied experimentally as a function of the temperature and the angle of emission by means of a quartz microbalance. The absolute flux measurement permitted to derive Antoine's coefficient for the calcium sample used: A=8.98± 0.07 and B=7787± 110 in standard unit. The angular FWHM of the atom flux distribution is found to be 53.7±7.3∘ at 848 K, temperature at which the gas behaviour is non collisional. The atom flux hysteresis observed experimentally in several laboratories is explained as follows: at first calcium heating, the evaporation comes from the sample only, resulting in a small evaporation rate. Once a full calcium layer has formed on the crucible refractory wall, the calcium evaporation surface includes the crucible's enhancing dramatically the evaporation rate for a given temperature. A Monte-Carlo code, developed to reproduce and investigate the oven behaviour as a function of temperature is presented. A discussion on the gas regime in the oven is proposed as a function of its temperature. A fair agreement between experiment and simulation is found.
Old groundwater buffers the effects of a major drought in groundwater-dependent ecosystems of the eastern Sierra Nevada (CA)
Authors: Meyers Zachary P , Frisbee Marty D , Rademacher Laura K , Stewart-Maddox Noah S
Published: April 2021

Global groundwater resources are stressed and the effects of climate change are projected to further disrupt recharge processes. Therefore, we must identify the buffers to climate change in hydrogeologic systems in order to understand which groundwater resources will be disproportionally affected by these changes. Here, we utilize a novel combination of remote sensing (e.g. Landsat) and groundwater residence time data (3H, 36Cl) to identify the factors controlling the hydrogeologic stability of aridland mountain-front springs in response to a major climate event, the 2011–2017 California drought. Desert springs within Owens Valley (CA) support unique ecosystems that are surrounded by lush, green vegetation sustained only by discharging groundwater and are not reliant on localized precipitation. Therefore, the health or ecological response of this vegetation is a direct reflection of the hydrogeologic stability of the mountain-block groundwater system since water is the limiting resource for riparian plant growth in arid regions. We compared spring water residence times to vegetation health metrics computed from Landsat imagery leading up to and during the drought interval. We observe that the vegetation surrounding springs discharging a high fraction of modern and bomb-pulse groundwater (<100 years) showed evidence of increased drying and desiccation as the drought progressed. In comparison, springs discharging a higher fraction of old groundwater (>100 years) showed little response thereby supporting the conceptual model where old groundwater, i.e. a distribution of deep and stable groundwater flowpaths, buffers short- to long-term climate perturbations and may provide hydrogeologic resistance to future effects from climate change.
Global changes in the spatial extents of precipitation extremes
Authors: Tan Xuezhi , Wu Xinxin , Liu Bingjun
Published: April 2021

Understanding the variability of spatial extents of precipitation extremes favors an accurate assessment of the severity of disasters caused by extreme precipitation events. Using a restricted neighborhood method, we identify the spatial extents of global precipitation extremes over 1983–2018 and examine their spatiotemporal variability and associated changes. Results show that the mid-latitudes shows the largest spatial extent of precipitation extremes, and the spatial extents in non-tropical regions over the Northern Hemisphere show significant seasonal differences. In non-monsoon regions, the spatial extents of precipitation extremes in autumn and winter are larger than those in spring and summer, and the annual average spatial extents of precipitation extremes all exceed 500 km, which are larger than those in monsoon regions. All the five non-monsoon regions over the Northern Hemisphere and three monsoon regions in the western Pacific show statistically significant increases in the spatial extent of precipitation extremes in most seasons.
Financial inclusion may limit sustainable development under economic globalization and climate change
Authors: Li Ang , Gao Lei , Chen Shi , Zhao Jinling , Ujiyad Saqirilatu , Huang Jianhui , Han Xingguo , Bryan Brett A
Published: April 2021

Financial inclusion is a key policy for achieving the UN Sustainable Development Goals worldwide. However, emerging evidence has challenged the universal effectiveness of this policy. Combining a cross-sectional socio-economic and ecological survey with regional macro-economic and climatic data, we undertook an integrated causal analysis of the impact of financial inclusion policy on the Inner Mongolian herder social-ecological system. Exposure to economic globalization and climate change threatened herder livelihoods via increased feed costs and reduced livestock sales prices. Financial inclusion loans were beneficial for herders with large grassland plot size who used their traditional ecological knowledge to adapt via seasonal herd mobility. However, most herders were sedentary, constrained by small plot size, and used financial inclusion loans to reserve livestock and maintain high stocking densities. This strategy exposed them to inflated feed costs, increased their debt, and led to widespread grassland degradation. The results illustrate the limitations of financial inclusion policy in achieving sustainable development when people are trapped in poverty, subject to novel social-ecological contexts, and their ability to adapt is compromised. Transformative adaptations based on community cooperation, traditional knowledge and institutions, complementary public policies, and technological innovation are crucial to support financial inclusion policy and enhance sustainable development.