bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optical frequency standard with a single 171Yb+ ion
Authors: Chepurov S.V. , Pavlov N.A. , Lugovoy A.A. , Bagayev S.N. , Taichenachev A.A. 
Published: May 2021

Abstract
We report recent results on the development of an optical frequency standard based on the quadrupole transition in a single 171Yb+ ion. The probe laser frequency is simultaneously stabilised to the transmission peak of a Fabry – Perot reference cavity and the central resonance of the quadrupole transition of the ion with a linewidth of 30 Hz. With the experimentally obtained spectral characteristics of the probe laser and optical reference, a daily frequency stability on the order of 10−17 is demonstrated for the 171Yb+ standard.
Loss of atoms from a near-resonance hollow dipole trap
Authors: Vinogradov V.A. , Karpov K.A. , Turlapov A.V. 
Published: May 2021

Abstract
The lifetime of a gas of 6Li atoms in a large hollow optical dipole trap formed by radiation with a frequency detuned by 4 or 2 GHz upward from resonance is measured. The trap has the shape of a thin-walled cylinder with flat bases and a volume of ∼1 mm3. The main mechanism responsible for the loss of atoms is heating due to Rayleigh scattering. The influence of collisions of atoms with the background gas and with each other on the measured lifetime is negligible.
Generalised Ramsey methods for suppressing light shifts in atomic clocks based on the coherent population trapping effect
Authors: Kovalenko D.V. , Basalaev M.Yu. , Yudin V.I. , Zanon-Willette T. , Taichenachev A.V. 
Published: May 2021

Abstract
We study the possibility of suppressing light shifts in Ramsey spectroscopy of coherent population trapping (CPT) using generalised autobalanced Ramsey spectroscopy (GABRS) and combined error signal in Ramsey spectroscopy (CESRS). We consider CPT resonances excited by a coherent bichromatic field in an open Λ-system with a ‘trap’ state. Using a rigorous mathematical proof and numerical calculations, these methods are shown to lead to complete suppression of the light shift and its fluctuations. Implementation of GABRS and CESRS in CPT clocks can markedly improve accuracy and long-term stability of these devices. These methods can also be applied in atomic CPT magnetometers and interferometers.
Associations of Alcohol, Marijuana, and Polysubstance use with Non-Adherence to COVID-19 Public Health Guidelines in a US Sample
Authors: Fendrich Michael , Becker Jessica , Park Crystal , Russell Beth , Finkelstein-Fox Lucy , Hutchison Morica 
Published: May 2021

Background We sought to understand the association between heavy alcohol and frequent drug use and non-adherence to recommended social distancing and personal hygiene guidelines for preventing the spread of COVID-19 early in the US pandemic. Methods A survey was offered on the crowdsourcing platform, Amazon Mechanical Turk (MTurk) during April 2020 (the early days of strict, social distancing restrictions). The study included 1,521 adults ages 18 years and older who resided in the US and were enrolled as MTurk workers, i.e., workers who are qualified by Amazon to complete a range of human interaction tasks, including surveys through the MTurk worker platform. Main predictors included measures of heavy drinking, marijuana, and polysubstance use. The dependent measures were measures of social distancing and personal hygiene, based on guidelines recommended at the time of the survey by the US Centers for Disease Control to prevent the spread of COVID-19. Results We found consistent negative associations between heavy drinking and drug use and adherence to social distancing and personal hygiene. Additionally, three control variables, age, gender, and race/ethnicity, were significant correlates of adherence to these measures. Conclusions The findings here are consistent with previous research exploring links between substance use and other adverse health behaviors. Further, the negative association between heavy drinking (five or more drinks in one sitting) and adherence underscore the public health risks entailed with the unrestricted reopening of public drinking establishments.
Exploring governance tensions of disruptive technologies: the case of care robots in Australia and New Zealand
Authors: Dickinson Helen , Smith Catherine , Carey Nicole , Carey Gemma 
Published: May 2021

ABSTRACTRobots are increasingly appearing as a potential answer to the ‘care crisis’ facing a number of countries. Although it is anticipated that many positives will flow from the application of these technologies, they are also likely to generate unexpected consequences and risks. This paper explores the use of robots within disability and aged care settings in the Australian and New Zealand contexts. Informed by thirty-five semi-structured interviews with a range of stakeholders, the paper explores why this area is so difficult to govern examining areas identified as generating tensions around the use of robots in care settings. In each of these areas some respondents saw the introduction of robots to be relatively straightforward applications that do not require extensive structures of governance. Others, however, viewed these applications as having potentially greater implications and the need to govern for these over the longer term. The three areas of tension that we explore in this paper relate to independence and surveillance, the re-shaping of human interaction and who can care. These tensions illustrate some of the problems involved in governing robots in a care service context and some of the potentially difficult issues that governments will need to resolve if these technologies are to be effective. We conclude the paper arguing what is needed is a responsive regulation approach to help resolve some of the complexities and tensions in overseeing these technologies.
Physical training considerations for optimizing performance in essential military tasks
Authors: Vaara Jani P. , Groeller Herbert , Drain Jace , Kyröläinen Heikki , Pihlainen Kai , Ojanen Tommi , Connaboy Chris , Santtila Matti , Agostinelli Philip , Nindl Brad C. 
Published: May 2021

ABSTRACTPhysically demanding essential military tasks include load carriage, manual material handling and casualty evacuation. This narrative review characterizes the main physical attributes related to performance of these occupational tasks and reviews physical training intervention studies in military settings to improve performance in these military tasks. Load carriage performance requires both aerobic and neuromuscular fitness with greater emphasis on maximal strength and absolute maximal oxygen uptake, especially when carrying heavier loads. In manual material handling, maximal strength and power are strongly associated with discrete lifting, while muscular strength, muscular endurance and aerobic fitness are also associated with repetitive lifting performance. Maximal strength including grip strength, muscular endurance, absolute maximal oxygen uptake and anaerobic capacity are associated with casualty evacuation performance. The results of the present review particularly emphasize the role of muscular fitness in successful performance of the reviewed military occupational tasks. Training intervention studies indicate that load carriage performance can be effectively improved by combining strength, aerobic and specific load carriage training. Improvement in maximal lifting capacity can be achieved by strength training or combined strength and aerobic training, while strength and aerobic training alone, or their combination are effective in improving repetitive lifting, and carry tasks. Only a few studies are available for casualty evacuation and the results are inconclusive but may indicate benefits of strength or combined training. Moreover, emphasis on lower volume but higher intensity in combined training may be a feasible and effective mode to improve military occupational performance in recruits and active‐duty soldiers.
Quantification of urban greenery using hemisphere-view panoramas with a green cover index
Authors: Zhang Yonglin , Li Shanlin , Fu Xiao , Dong Rencai 
Published: May 2021

ABSTRACT
Urban greenery has positive impacts on the well-being of residents and provides vital ecosystem services. A quantitative evaluation of full-view green coverage at the human scale can guide green space planning and management. We developed a still camera to collect hemisphere-view panoramas (HVPs) to obtain in situ heterogeneous scenes and established a panoramic green cover index (PGCI) model to measure human-scale green coverage. A case study was conducted in Xicheng District, Beijing, to analyze the quantitative relationships of PGCI with the normalized difference vegetation index (NDVI) and land surface temperature (LST) in different land use scenarios. The results show that the HVP is a useful quantization tool: (1) the method adaptively distinguishes the green cover characteristics of the four functional areas, and the PGCI values are ranked as follows: recreational area (29.6) > residential area (19.0) > traffic area (15.9) > commercial area (12.5); (2) PGCI strongly explains NDVI and LST, and for each unit (1%) increase in PGCI, NDVI tends to increase by 0.007, and (3) LST tends to decrease by 0.21 degrees Celsius. This research provides government managers and urban planners with tools to evaluate green coverage in complex urban environments and assistance in optimizing human-scale greenery and microclimate.
Discovery of superconductivity in AlB2-type hexagonal YGa2
Authors: Tran V H , Sahakyan M , Bukowski Z 
Published: May 2021

Abstract
A crystalline sample YGa2 with the AlB2-type hexagonal structure has been synthesized using the self-flux method. We measured electrical resistivity and specific heat down to 0.4 K and in fields up to 200 mT. The obtained data reveal type-II superconductivity. Unusual behaviour of the temperature dependence of upper critical field H

c2(T
c) was attributed to the crystal twinning of two phases possessing close lattice parameters. We determined thermodynamic parameters in the superconducting and normal states of YGa2. DFT calculations indicated a large change in the Fermi velocity of carriers nearby cylinder-like structured Fermi surface along the Γ − A line.
A novel deep neural network based on an unsupervised feature learning method for rotating machinery fault diagnosis
Authors: Cheng Chun , Liu Wenyi , Wang Weiping , Pecht Michael 
Published: May 2021

Abstract
As a simple and unsupervised feature learning method, sparse filtering has shown potential in rotating machinery fault diagnosis. However, sparse filtering has the following deficiencies: (a) the optimal sparsity of the learned features cannot be determined. (b) As a shallow network, sparse filtering has a limited capability of learning discriminative features under varying loads. (c) The diagnostic accuracy and robustness are insufficient. To overcome these deficiencies, variant sparse filtering (VSF), which can determine the optimal sparsity, is developed. Then, a deep variant sparse filtering network (DVSFN) is constructed by using stacked VSF to enhance the capability of learning discriminative features. Finally, a novel fault diagnosis method using the DVSFN is presented and verified by using rolling bearing and planetary gearbox datasets. The optimal sparsity of the learned features is determined by parametric analysis. The experimental results show that the DVSFN can adaptively learn discriminative features, irrespective of the varying loads, and the developed diagnostic method can achieve higher testing accuracy and stronger robustness in comparison to classic data-driven methods.
Possibility evaluation of the optical imaging of proton mini-beams
Authors: Yamamoto Seiichi , Yabe Takuya , Akagi Takashi 
Published: May 2021

Abstract
Proton therapy using mini-beams is a promising method to reduce radiation damage to normal tissue. However, distribution measurements of mini-beams are difficult due to their small structures. Since optical imaging is a possible method to measure high-resolution two-dimensional dose distribution, we conducted optical imaging of an acrylic block during the irradiation of mini-beams of protons. Mini-beams were made from a proton pencil beam irradiated to 1 mm slits made of tungsten plate. During irradiation of the mini-beams to the acrylic block, we measured the luminescence of the acrylic block using a charge-coupled device camera. With the measurements, we could obtain slit beam images that have slit shapes in the shallow area while they were uniform in their Bragg peaks, which was similar to the case of simulated optical images by Monte Carlo simulations. We confirmed that high-resolution optical imaging of mini-beams is possible and provides a promising method for efficient quality assessment of mini-beams as well as research on mini-beam therapy.
Strong coupling effects in quantum thermal transport with the reaction coordinate method
Authors: Anto-Sztrikacs Nicholas , Segal Dvira 
Published: May 2021

Abstract
We present a semi-analytical approach for studying quantum thermal energy transport at the nanoscale. Our method, which is based on the reaction coordinate method, reveals the role of strong system-bath coupling effects in quantum energy transport. Considering as a case study the nonequilibrium spin-boson model, a collective coordinate is extracted from each thermal environment and added into the system to construct an enlarged system (ES). After performing additional Hamiltonian’s truncation and transformation, we obtain an effective two-level system with renormalized parameters, resulting from the strong system-bath coupling. The ES is weakly coupled to its environments, thus can be simulated using a perturbative Markovian quantum master equation approach. We compare the heat current characteristics of the effective two-state model to other techniques, and demonstrate that we properly capture strong system-bath signatures such as the turnover behavior of the heat current as a function of system-bath coupling strength. We further investigate the thermal diode effect and demonstrate that strong couplings moderately improve the rectification ratio relative to the weak coupling limit. The effective Hamiltonian method that we developed here offers fundamental insight into the strong coupling behavior, and is computationally economic. Applications of the method toward studying multi-level quantum thermal machines are anticipated.
Comment on Solvable model of bound states in the continuum (BIC) in on dimension (2019, 94, 105214)
Authors: Jones H F 
Published: May 2021

Abstract
We elucidate the status of the special scattering states found in this paper and explore further the relationships between scattering states and bound states of different non-analytic segments (depending on ∣x∣) of the exponential potential.
Relativistic quantum dynamics of scalar particles in the rainbow formalism of gravity
Authors: Kangal E E , Salti M , Aydogdu O , Sogut K 
Published: May 2021

Abstract
In the present article, we investigate the Klein–Gordon equation (KGE) in a topologically trivial Gödel-type space-time in the context of rainbow gravity (RG). Exact solutions and energy spectrum of scalar particles are obtained for the considered model. Also, the same systems are studied with the existence of the Klein–Gordon oscillator (KGO) potential. Results are evaluated by considering two different rainbow functions and they are analyzed graphically. We observe that the energy spectrum of scalar particles is modified by rainbow functions compared to the solutions obtained via the ordinary general relativity (GR) theory.
Prospects of future CMB anisotropy probes for primordial black holes
Authors: Cang Junsong , Gao Yu , Ma Yin-Zhe 
Published: May 2021

Abstract
Cascade of particles injected as Hawking Radiation from Primordial Black Holes (PBH) can potentially change the cosmic recombination history by ionizing and heating the intergalactic medium, which results in altering the anisotropy spectra of the Cosmic Microwave Background (CMB). In this paper, we study the expected sensitivity of several future CMB experiments in constraining the abundance of PBHs distributed in 1015∼1017 g mass window according to four mass functions: the monochromatic, log-normal, power-law and critical collapse models. Our result shows that future experiments, such as CMB-S4 and PICO, can improve the current Planck bounds by about two orders of magnitude. Most regions in PBH parameter space that are allowed by current CMB data, including monochromatically distributed PBHs with mass heavier than 3.8 × 1016 g, can be tested by upcoming missions with high significance.
The Lyα forest flux correlation function: a perturbation theory perspective
Authors: Chen Shi-Fan , Vlah Zvonimir , White Martin 
Published: May 2021

Abstract
The Lyα forest provides one of the best means of mapping large-scale structure at high redshift, including our tightest constraint on the distance-redshift relation before cosmic noon. We describe how the large-scale correlations in the Lyα forest can be understood as an expansion in cumulants of the optical depth field, which itself can be related to the density field by a bias expansion. This provides a direct connection between the observable and the statistics of the matter fluctuations which can be computed in a systematic manner. We discuss the way in which complex, small-scale physics enters the predictions, the origin of the much-discussed velocity bias and the `renormalization' of the large-scale bias coefficients. Our calculations are within the context of perturbation theory, but we also make contact with earlier work using the peak-background split. Using the structure of the equations of motion we demonstrate, to all orders in perturbation theory, that the large-scale flux power spectrum becomes the linear spectrum times the square of a quadratic in the cosine of the angle to the line of sight. Unlike the case of galaxies, both the isotropic and anisotropic pieces receive contributions from small-scale physics.
CMB birefringence from ultralight-axion string networks
Authors: Jain Mudit , Long Andrew J. , Amin Mustafa A. 
Published: May 2021

Abstract
The polarization of Cosmic Microwave Background (CMB) photons is rotated as they pass through (ultralight-) axion string loops. Studying this birefringence can reveal valuable information about the axion-photon coupling and the structure of the string network. We develop an approximate analytic formalism and identify a kernel function that can be used to calculate the two-point correlation function for CMB birefringence induced by an arbitrary axion string network. Using this formalism, we evaluate the birefringence signal for some simple loop distributions (including scaling and network collapse). We find that the angular correlation function has a characteristic angular scale set by θmin, which corresponds to the angular extent of the loops at the time of recombination. This results in a peak in the birefringence power spectrum around ℓp ∼ 1/θmin. An additional scale, controlled by the axion's mass, is introduced if the network collapses before today.
Clear evidence of a clusters in the ground state of heavy nuclei
Authors: Tanaka Junki , Yang Zaihong , Typel Stefan 
Published: May 2021

Abstract
We obtained clear evidence of α clustering at the surface of heavy nuclei by measuring the cross sections for quasi-free α-knockout reactions along the tin isotopic chain. The α-cluster appearance at the nuclear surface could not only be a natural explanation for the α-preformation in the α-decay theory, but also provides the modification to the relation between neutron-skin thicknesses Δτηρ and a slope parameter L in the nuclear equation of state.
Study on the relative collection efficiency of large area PMTs
Authors: Ma L. , Xia J. , Qian S. , Gao F. , Huang G. , Wu Q. , Sun J. , Ren L. , Si S. , Zhu Y. , Wang Z. 
Published: May 2021

Abstract
The relative collection efficiency (CE) of 20-inch
Photomultiplier Tubes (PMTs) cannot be measured directly, but it can
be obtained by the quantum efficiency (QE) of the photocathode and
the relative detection efficiency (DE) of the PMTs. The measurements
of relative CE and its spherical uniformity of the 20-inch PMTs have
been introduced in this manuscript, and the difference in
performance between Microchannel-Plate PMT (MCP-PMT) and Dynode-PMT
were shown. The CE performance for 20-inch PMTs are given and the
batch test results of CE for MCP-PMTs and Dynode-PMTs are compared
at the end of this manuscript.
Sharing the seas: a review and analysis of ocean sector interactions
Authors: Crona Beatrice , Wassénius Emmy , Lillepold Kate , Watson Reg A , Selig Elizabeth R , Hicks Christina , Österblom Henrik , Folke Carl , Jouffray Jean-Baptiste , Blasiak Robert 
Published: May 2021

Abstract
Ocean activities are rapidly expanding as Blue Economy discussions gain traction, creating new potential synergies and conflicts between sectors. To better manage ocean sectors and their development, we need to understand how they interact and the respective outcomes of these interactions. To provide a first comprehensive picture of the situation, we review 3187 articles to map and analyze interactions between economically important ocean sectors and find 93 unique direct and 61 indirect interactions, often mediated via the ocean ecosystem. Analysis of interaction outcomes reveals that some sectors coexist synergistically (e.g. renewable energy, tourism), but many interactions are antagonistic, and negative effects on other sectors are often incurred via degradation of marine ecosystems. The analysis also shows that ocean ecosystems are fundamental for supporting many ocean sectors, yet 13 out of 14 ocean sectors have interactions resulting in unidirectional negative ecosystem impact. Fishing, drilling, and shipping are hubs in the network of ocean sector interactions, and are involved in many of the antagonistic interactions. Antagonistic interactions signal trade-offs between sectors. Qualitative analysis of the literature shows that these tradeoffs relate to the cumulative nature of many ecosystem impacts incurred by some sectors, and the differential power of ocean sectors to exert their rights or demands in the development of the ocean domain. There are also often time lags in how impacts manifest. The ocean governance landscape is not currently well-equipped to deal with the full range of trade-offs, and opportunities, likely to arise in the pursuit of a Blue Economy in a rapidly changing ocean context. Based on our analysis, we therefore propose a set principles that can begin to guide strategic decision-making, by identifying both tradeoffs and opportunities for sustainable and equitable development of ocean sectors.