bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser cooling of atoms at narrow optical transitions in fields with a polarisation gradient
Authors: Il’enkov R.Ya. , Prudnikov O.N. , Taichenachev A.V. , Yudin V.I. 
Published: June 2020

Abstract
The efficiency of the polarisation mechanisms of laser cooling of atoms is analysed using narrow optical transitions for which the recoil energy is greater than or comparable to the natural line width. By the example of atoms with the J
g = 1 → J
e = 2 optical transition (J
g and J
e are the total angular momenta of the ground and excited states) in the resonant light fields of σ
+ – σ
– and lin⊥lin configurations, the analysis of the minimum achievable energies of laser-cooled atoms is performed. It is shown that the polarisation mechanisms of laser cooling under conditions of a significant influence of recoil effects become less efficient and do not lead to average kinetic energies of an ensemble of atoms below the Doppler limit.
Miniature quantum frequency standard based on the phenomenon of coherent population trapping in vapours of 87Rb atoms
Authors: Skvortsov M.N. , Ignatovich S.M. , Vishnyakov V.I. , Kvashnin N.L. , Mesenzova I.S. , Brazhnikov D.V. , Vasil’ev V.A. , Taichenachev A.V. , Yudin V.I. , Bagayev S.N. , Blinov I.Yu. , Pal’chikov V.G. , Samokhvalov Yu.S. , Parekhin D.A. 
Published: June 2020

Abstract
We report the results of the development and production of a quantum frequency standard (QFS) based on the coherent population trapping (CPT) resonance observed on the D1 absorption line of 87Rb atoms. The effect of various physical factors on the QFS frequency is studied, and the optimal physical parameters of the device to attain the best frequency stability are determined. The measured relative frequency instability (Allan deviation) is ∼9 × 10−12 for the averaging time of 1 s, 3 ×10−13 for 1000 s, and 1.5 ×10−12 for 24 hours. For a volume of 60 cm3, the power consumption of the entire device is 300 mW. The designed QFS can be used in a new-generation satellite navigation systems with increased accuracy and reliability, as well as for solving a number of other problems of science and technology.
Trapping of lithium atoms in a large hollow optical dipole trap
Authors: Vinogradov V.A. , Karpov K.A. , Lukashov S.S. , Turlapov A.V. 
Published: June 2020

Abstract
We describe the trapping of lithium atoms in an optical dipole trap about 1 mm in size, with a nearly rectangular potential. The trap has the shape of a cylinder with flat bases. The confinement region is bounded by thin walls produced by light with a frequency blue-detuned from an atomic transition (resonance) frequency by 19 GHz. Before trapping, the gas is collected and cooled in a magneto-optical trap whose centre nearly coincides with the centre of the dipole trap. After switching off the magneto-optical trap, we have photographed the atoms remaining in the dipole trap.
Effect of boundary conditions on fluctuations of the Bose condensate of interacting atoms
Authors: Tarasov S.V. 
Published: June 2020

Abstract
For a gas of trapped interacting atoms forming a Bose condensate, we demonstrate a possibility of a significant influence of the boundary conditions on the statistics of the number of particles in the fundamental mode of the system. The analysis is carried out in the Bogoliubov – Popov low-temperature approximation for model homogeneous cubic traps with periodic or combined periodic and zero boundary conditions. It is shown that the effect of the boundary conditions does not weaken even in the region of parameters corresponding to the relatively strong interaction in the Thomas – Fermi asymptotic case, and does not disappear when proceeding to the thermodynamic limit.
Study of saturated-absorption resonances on the 3P0, 1, 2 – 3D1, 2, 3 transitions of magnesium atoms in a hollow-cathode discharge cell
Authors: Goncharov A.N. , Klimacheva O.A. , Mel’nikova A.O. 
Published: June 2020

Abstract
The saturated-absorption resonances on the 3P0, 1, 2 – 3D1, 2, 3 transitions of magnesium atoms in a hollow-cathode discharge cell are studied. The line width (FWHM) for the observed saturated-absorption resonance on the 33P0 → 33D1 transition turns out to be ∼220 MHz. Experiments are performed using a system based on a 766-nm diode laser with amplification and frequency doubling in a nonlinear BiBO crystal. The results obtained are of interest for sub-Doppler cooling on the 33P2 → 33D3 transition.
Common homozygosity for predicted loss-of-function variants reveals both redundant and advantageous effects of dispensable human genes
Authors: Rausell Antonio , Luo Yufei , Lopez Marie , Seeleuthner Yoann , Rapaport Franck , Favier Antoine , Stenson Peter D. , Cooper David N. , Patin Etienne , Casanova Jean-Laurent , Quintana-Murci Lluis , Abel Laurent 
Published: June 2020

Significance
Human genes homozygous for apparent loss of function (LoF) variants are increasingly reported in a sizeable proportion of individuals without overt clinical phenotypes. Here, we found 166 genes with 179 predicted LoF variants for which the frequency of homozygous individuals exceeds 1% in at least one of the populations present in databases ExAC and gnomAD. These putatively dispensable genes showed relaxation of selective constraints, suggesting that a considerable proportion of these genes may be undergoing pseudogenization. Eight of these LoF variants displayed robust signals of positive selection, including two variants in genes involved in resistance to infectious diseases. The identification of dispensable genes will facilitate the identification of functions that are now redundant, or possibly even advantageous, for human survival.
Global variation in the thermal tolerances of plants
Authors: Lancaster Lesley T. , Humphreys Aelys M. 
Published: June 2020

Significance
Knowledge of how thermal tolerances are distributed across major clades and biogeographic regions is important for understanding biome formation and climate change responses. However, most research has concentrated on animals, and we lack equivalent knowledge for other organisms. Here, we compile global data on heat and cold tolerances of plants, showing that many, but not all, broad-scale patterns known from animals are also true for plants. Importantly, failing to account simultaneously for influences of local environments, and evolutionary and biogeographic histories, can mislead conclusions about underlying drivers. Our study unravels how and why plant cold and heat tolerances vary globally and highlights that all plants, particularly at mid-to-high latitudes and in their nonhardened state, are vulnerable to ongoing climate change.
A continuous reaction network that produces RNA precursors
Authors: Yi Ruiqin , Tran Quoc Phuong , Ali Sarfaraz , Yoda Isao , Adam Zachary R. , Cleaves H. James , Fahrenbach Albert C. 
Published: June 2020

Significance
RNA may have been the original polymer to arise spontaneously on the early Earth through natural geochemistry. Although direct physical evidence regarding early Earth’s geochemistry is extremely limited, complex chemical reaction networks are thought to have played an important role in chemical evolution. The present study demonstrates an experimental model reaction network that generates a number of compounds that can lead to RNA synthesis in a single mixture starting from simple organic and inorganic feedstocks. Models of this type will help explain which conditions are needed to produce RNA in primitive planetary settings.
A cost-effectiveness analysis of the number of samples to collect and test from a sexual assault
Authors: Wang Zhengli , MacMillan Kevin , Powell Mark , Wein Lawrence M. 
Published: June 2020

Significance
Within the context of sexual assaults, we address a fundamental issue in criminal investigations: how much evidence to collect and process. Using data from the San Francisco Police Department, we show that machine learning algorithms outperform sexual assault forensic examiners at identifying probative samples. Relative to selective testing of samples, testing all DNA samples in a sexual assault kit more than doubles the number of sexual assault kits generating a DNA profile that can be entered into the criminal DNA database, at only a slightly lower benefit-to-cost ratio. Our results suggest that the yield of DNA profiles for the database would increase another 47.2% by collecting samples from the three most probative locations (as deemed by the machine learning algorithm).
High-throughput photocapture approach for reaction discovery
Authors: Bayly Alison A. , McDonald Benjamin R. , Mrksich Milan , Scheidt Karl A. 
Published: June 2020

Significance
Mass spectrometry (MS) has inspired powerful modes of reaction discovery. Chemists often rely on MS methods, such as liquid-chromatography MS and gas chromatography MS, to rapidly assess hundreds of small-scale reactions. These chromatography-based MS techniques are preferred as they typically provide data consistent with scaled-up yields. Other MS approaches that more rapidly analyze reactions frequently provide results inconsistent with scaled-up yields. Herein we describe the development of a high-throughput platform that overcomes the analytical bottleneck presented by chromatography-based MS techniques while retaining consistency with scaled-up results. Our MS method, which combines diazirine photocapture and self-assembled monolayers for desorption/ionization MS, enabled the analysis of ∼2,000 reactions in <2.5 h to realize an intermolecular photoredox reaction.
“It’s writtenniistobut it sounds likeknee stew.”
Authors: Genee Inge 
Published: June 2020

AbstractThis paper argues for pragmatism rather than linguistic purity in orthography design for endangered Indigenous languages such as Blackfoot, emphasizing the need to see orthography standardization as a dynamic process rather than a static result. It explores the ongoing lack of community agreement about the best way to write the Blackfoot language and lack of widespread proficiency in the use of its standard orthography, and then describes ways in which this is mitigated in the Blackfoot Language Resources and Digital Dictionary project, a suite of web resources created to support language maintenance and revitalization work. The website uses a combination of relaxed searches, alternative spelling fields, and multimedia content to increase accessibility of the resources for users lacking proficiency in the standard orthography.
Physics postgraduate teaching assistants’ grading approaches: conflicting goals and practices
Authors: Marshman Emily , Maries Alexandru , Sayer Ryan T , Henderson Charles , Yerushalmi Edit , Singh Chandralekha 
Published: June 2020

Abstract
Grading can shape students’ learning and encourage use of effective problem solving practices. Teaching assistants (TAs) are often responsible for grading student solutions and providing feedback, thus, their perceptions of grading may impact grading practices in the physics classroom. Understanding TAs’ perceptions of grading is instrumental for curriculum developers as well as professional development leaders interested in improving grading practices. In order to identify TAs’ perceptions of grading, we used a data collection tool designed to elicit TAs’ considerations when making grading decisions as well as elicit possible conflicts between their stated goals and actual grading practices. The tool was designed to explicate TAs’ attitudes towards research-based grading practices that promote effective problem solving approaches. TAs were first asked to state their goals for grading in general. Then, TAs graded student solutions in a simulated setting while explicating and discussing their underlying considerations. The data collection tool was administered at the beginning of TAs’ first postgraduate teaching appointment and again after one semester of teaching experience. We found that almost all of the TAs stated that the purpose of grading was formative, i.e. grading should encourage students to learn from their mistakes as well as inform the instructor of common student difficulties. However, when making grading decisions in a simulated setting, the majority of TAs’ grading considerations focused on correctness and they did not assign grades in a way that encourages use of effective problem solving approaches. TAs’ perceptions of grading did not change significantly during one semester of teaching experience.
Never far from shore: productive patterns in physics students’
use of the digital learning environment Algodoo
Authors: Euler Elias , Prytz Christopher , Gregorcic Bor 
Published: June 2020

Abstract
In this paper, we present three types of activity that we have observed during
students’ free exploration of a software called
Algodoo
, which allows students to explore a range of
physics phenomena within the same digital learning environment. We discuss how,
by responding to any of the three activity types we identify in the
students’ use of Algodoo, physics teachers can
springboard into a range of relevant physics discussions while supporting and
valuing student agency and divergent thinking. Thus, while one might not expect
students’ undirected use of a digital tool such as
Algodoo to be particularly worthwhile for the physics
classroom, we highlight how students are never ‘far from the shore’
of a productive physics discussion.
Analysis of ultra-short bunches in free-electron lasers
Authors: Campbell L T , Freund H P , Henderson J R , McNeil B W J , Traczykowski P , van der Slot P J M 
Published: June 2020

Abstract
Free-electron lasers (FELs) operate at wavelengths from millimeter waves through hard x-rays. At x-ray wavelengths, FELs typically rely on self-amplified spontaneous emission (SASE). Typical SASE emission contains multiple temporal ‘spikes’ which limit the longitudinal coherence of the optical output; hence, alternate schemes that improve on the longitudinal coherence of the SASE emission are of interest. In this paper, we consider electron bunches that are shorter than the SASE spike separation. In such cases, the spontaneously generated radiation consists of a single optical pulse with better longitudinal coherence than is found in typical SASE FELs. To investigate this regime, we use two FEL simulation codes. One (MINERVA) uses the slowly-varying envelope approximation (SVEA) which breaks down for extremely short pulses. The second (PUFFIN) is a particle-in-cell simulation code that is considered to be a more complete model of the underlying physics and which is able to simulate very short pulses. We first anchor these codes by showing that there is substantial agreement between the codes in simulation of the SPARC SASE FEL experiment at ENEA Frascati. We then compare the two codes for simulations using electron bunch lengths that are shorter than the SASE slice separation. The comparisons between the two codes for short bunch simulations elucidate the limitations of the SVEA in this regime but indicate that the SVEA can treat short bunches that are comparable to the cooperation length.
A comparative study of materials assembled from recombinant K31 and K81 and extracted human hair keratins
Authors: Parker Rachael N , Trent Alexis , Roth Stefaniak Kristina L , Van Dyke Mark E , Grove Tijana Z 
Published: June 2020

Abstract
Natural biopolymers have found success in tissue engineering and regenerative medicine applications. Their intrinsic biocompatibility and biological activity make them well suited for biomaterials development. Specifically, keratin-based biomaterials have demonstrated utility in regenerative medicine applications including bone regeneration, wound healing, and nerve regeneration. However, studies of structure-function relationships in keratin biomaterials have been hindered by the lack of homogeneous preparations of materials extracted and isolated from natural sources such as wool and hair fibers. Here we present a side-by-side comparison of natural and recombinant human hair keratin proteins K31 and K81. When combined, the recombinant proteins (i.e. rhK31 and rhK81) assemble into characteristic intermediate filament-like fibers. Coatings made from natural and recombinant dimers were compared side-by-side and investigated for coating characteristics and cell adhesion. In comparison to control substrates, the recombinant keratin materials show a higher propensity for inducing involucrin and hence, maturation in terms of potential skin cell differentiation.
Influence of stratospheric sudden warming on the tropical intraseasonal convection
Authors: Wang Feiyang , Han Yuanyuan , Zhang Shiyan , Zhang Ruhua 
Published: June 2020

Abstract
Madden–Julian oscillation (MJO), the dominant mode of intraseasonal variability in the tropical troposphere, has recently been shown to have a great impact on Northern Hemisphere (NH) extratropical stratosphere. But the influence of the variability in the extratropical stratosphere on MJO is seldom reported. In this study, the influence of major, mid–winter NH stratospheric sudden warmings (SSWs) on the MJO is investigated using meteorological reanalysis datasets. Our analysis reveals that SSWs also exert considerable influence on tropical intraseasonal convection. The occurrences of MJO phases 6 and 7 significantly increase during around 20 d after the onset of SSWs, corresponding to enhanced convective activity over the equatorial Central and Western Pacific. Then in the following days, the coherent eastward propagation of tropical intraseasonal convection resembles the periodic variation in a typical MJO. These results suggest that the extratropical stratosphere affects the organized tropical intraseasonal convection, and variability of the tropical intraseasonal convection related to MJO can be better grasped by taking extratropical stratospheric variability into account. Considering the complex interaction between MJO and extratropical stratosphere, further work on comprehensive understanding of the relationship between SSWs and MJO is required in future studies.
Research on Integrated Deployment Method of Digital Earth Thematic Application Model
Authors: Danpu Zhao , Xianqing Tai , Zhijie Ma 
Published: June 2020

Abstract
Nowadays, the digital earth not only relates to the technologies of surveying and mapping geography, but also includes the analysis and cross-application of various scientific data related to geographic information. It requires a computing environment and management for the corresponding thematic application models which supports the online analysis on the digital earth. So we proposed an integrated deployment method for digital earth thematic application models based on container cloud, which provides a flexible and scalable information integration and analysis architecture for digital earth. Firstly, a Docker image building module is designed to facilitate the user to quickly build the application model into a image. Then the Docker technology is used to implement the containerization of the application model to provide a stable running environment for the application model. Finally, the Kubernetes is used to dynamically manage the cluster resources to realize rapid expansion of computing resources. In addition, the HDFS is deployed, and the image files and various scientific data respectively store with Hbase and Apache file systems. It can ensure the read and write speed of the application model and the related data and log files. It also used zabbix framework to manage the monitoring index of the container cloud cluster to ensure the execution effect of the application model. Through the tests of typical application model, it is verified that the method can integrated deploy and apply the cross-domain, hetero-architecture, multi-version and multi-class application models on the digital earth.
Semi-supervised classification of hyperspectral images based on two branch autoencoder
Authors: Lei Z , Yi Z , Peng L , Hui S X 
Published: June 2020

Abstract
In this paper, we propose a novel semi-supervised method based on two branch autoencoder (TBAE) for hyperspectral images. A branch is classification function, and another branch is decoder function. Both of functions promote each other in training process. The encoder is fit for both classifier and decoder. The encoder and the decoder guide feature extraction from unlabeled samples. The encoder and the classifier guide classification for all labeled samples. We can get more information from unlabeled samples for classification. Finally, we use convolutional autoencoder (CAE) to extend TBAE and obtain TBCAE. Compared with ANN and CNN, TBAE and TBCAE have a better performance in the case of a small number of labeled samples. Use different datasets to verify these methods and print visualization of hidden layer and the reconstructed data. The results demonstrate that the proposed framework obtains credible results with a small number of labeled samples.
A multi-scale 3D convolution neural network for spectral-spatial classification of hyperspectral imagery
Authors: Qi Wenchao , Zhang Xia 
Published: June 2020

Abstract
Along with the remarkable achievements of various neural networks in the field of computer vision, deep learning methods have gradually been applied to hyperspectral image (HSI) classification. Traditional classification methods have several outstanding issues, including the insufficient hand-craft features and time-consuming and laborious feature extraction. We therefore propose a multi-scale, 3D convolutional neural network (CNN) framework (MSCNN), trained in an end-to-end manner for hyperspectral image classification. Using the original hyperspectral image as an input, the MSCNN framework leverages two branches of a 3D residual neural network to extract deep and abstract HSI features. Then, the HSI spectral-spatial features of different scales are fused and fed into the SoftMax layer to achieve an end-to-end hyperspectral image classification. Besides, data augmentation, dynamic learning rate, and regularization methods are used to promote the rapid convergence of MSCNN and avoid model over-fitting. Three well-known hyperspectral datasets (Indian Pines, University of Pavia and Pavia Center) were used to evaluate the classification performance of the proposed MSCNN method. The results indicate that, compared with the existing deep learning methods, the proposed MSCNN method achieves the best classification performance within the 20 training epochs. The overall accuracy (OA), average accuracy (AA), and kappa statistic (K) of MSCNN are 97.16%, 98.69% and 0.9665, respectively, for Indian Pines; 99.17%, 98.97% and 0.9888 for University of Pavia; and 99.87%, 99.70% and 0.9981 for Pavia Center.
A New Level of Detail Concept for Building Indoor Scene
Authors: Pang Yueyong , Yang Qiqi , Zhou Liangchen , Lin Bingxian , Lv Guonian 
Published: June 2020

Abstract
Concomitant with the acceleration of urbanization, the indoor scene of buildings becoming increasingly complex in recent years. In order to meet the needs of diverse indoor application analysis, the multi-level of detail (LOD) model of indoor scene has been paid increasing attention. However, there are two kinds of LODs in the fields of geographic information and building information, which cannot be effectively integrated. From the perspective of geographic scenario, this paper proposes a new concept of LOD to realize the construction of indoor scene model under different details. According to the effects on indoor space, the indoor components are divided into three semantic levels: enclosing component, connecting component and decorating component. Finally, several examples of indoor models combining semantic LOD, geometric LOD and process LOD are introduced.