bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sudden singularities in generalized hybrid metric-Palatini cosmologies
Authors: Rosa João Luís , Lobo Francisco S.N. , Rubiera-Garcia Diego 
Published: July 2021

Abstract
In this work, we explore cosmological sudden singularities
arising in the dynamically equivalent scalar-tensor representation
of generalized hybrid metric-Palatini gravity. Using a FLRW
background, we show that the structure of the field equations
prevents sudden singularities from arising at time derivatives of
the scale factor of orders lower than four, but that they are
allowed to appear for time derivatives of higher orders. Imposing an
ansatz for the scale factor, we provide an explicit solution where
these sudden singularities appear in the fourth-order time
derivative of the scale factor. A comparison of the Hubble and
deceleration parameters arising from this model with the
experimental measurements from the Planck Satellite allow us to
impose constraints on the time span for which the occurrence of
sudden singularities becomes likely in our universe, as measured
from the Big Bang.
Unveiling the nuclear matter EoS from neutron star properties: a supervised machine learning approach
Authors: Ferreira Márcio , Providência Constança 
Published: July 2021

Abstract
We explore supervised machine learning methods in extracting the non-linear maps between neutron stars (NS) observables and the equation of state (EoS) of nuclear matter.	Using a Taylor expansion around saturation density, we have generated a set of model independent EoS describing stellar matter constrained by nuclear matter parameters that are thermodynamically consistent, causal, and consistent with astrophysical observations. From this set, the full non-linear dependencies of the NS tidal deformability and radius on the nuclear matter parameters were learned using two distinct machine learning methods. Due to the high accuracy of the learned non-linear maps, we were able to analyze the impact of each nuclear matter parameter on the NS observables, identify dependencies on the EoS properties beyond linear correlations and predict which stars allow us to draw strong constraints.
Tensor spectrum of turbulence-sourced gravitational waves as a constraint on graviton mass
Authors: He Yutong , Brandenburg Axel , Sinha Aditya 
Published: July 2021

Abstract
We consider a generic dispersive massive gravity theory and numerically
study its resulting modified energy and strain spectra of tensor gravitational waves (GWs)
sourced by (i) fully developed turbulence during the electroweak phase
transition (EWPT) and (ii) forced hydromagnetic turbulence during
the QCD phase transition (QCDPT).
The GW spectra are then computed in both spatial and temporal Fourier domains.
We find, from the spatial spectra, that the slope modifications are
weakly dependent on the eddy size at QCDPT, and, from the temporal
spectra, that the modifications are pronounced in the 1–10 range
— the sensitivity range of the North American Nanohertz Observatory
for Gravitational Waves (NANOGrav) — for a graviton mass in the
range 2×10-23 c27×10-22.
Method for determining the state of an grounding device
Authors: Sidorov A , Abdullozoda R , Sadullozoda S , Saifiddinzoda O , Abdullozoda I 
Published: July 2021

Abstract
The article provides a method for determining the state of the grounding devices without having to open the vertical and horizontal electrodes thereof. The developed method requires the determination of the average annual significance of indirect factors, essentially influencing the corrosion state of the ground elements, such as ground humidity and the meaning wandering current.
Project implementation efficiency: developing natural gas resources of the Western Arctic shelf
Authors: Zhukov O V , Cherepovitsyn A E 
Published: July 2021

Abstract
The article discusses the issue of developing an optimal investment plan aimed at implementing large-scale projects for the production of natural gas in Western Arctic shelf areas. It presents the results of evaluating the economic efficiency of project implementation for two possible taxation scenarios: the one based on the current tax system and the one based on a production sharing agreement (PSA). The results obtained indicate that in implementing gas projects, it is advisable to use a step-by-step multivariate system for evaluating their commercial and fiscal efficiency taking into account the planned technical and organizational measures.
Mathematical modeling of filtering suspensions of non – newtonian behavior in alluvial filters
Authors: Ibyatov R I , Zinnatullina A N , Kiseleva N G 
Published: July 2021

Abstract
Clarification of liquids and preparation of industrial water plays an important role in various industries, in particular, in the development of oil fields, in the fuel oil industry. In this article, the filtration of a fine suspension of non-Newtonian behavior in a batch alluvial filter is considered. The power-law fluid model is used to describe the rheological state of the medium. A mathematical model is constructed for a filter element of the tubular type. To calculate the thickness of the formed sediment layer, differential equations are constructed. The results of numerical calculations are presented. The influence of the degree of nonlinearity of the medium on the duration of the filter cycle is shown.
Radiation Resistance Of Filled Elastomer Compositions
Authors: Ibadullaev A , Nigmatova D , Teshabaeva E 
Published: July 2021

Abstract
The paper investigates the physical and chemical properties of the carbon-containing material of the secondary raw material for the production of acetylene and its effect on the radiation resistance of rubber products and cable rubbers. It was found that the carbon-containing material is modified carbon, the surface of which is microencapsulated with oligomeric oxygen-containing compounds, its thickness, calculated from the value of the specific geometric surface, amounted to 50-60Å. The effect of carbon-containing material on the relaxation coefficient and compressive stress is shown, and radiation resistance by the relative elongation of rubbers in an ionizing radiation environment 60Co. At the same time, it was found that, due to the finished oligomer on the surface of particles of carbon-containing material, threshold dose of radiation of rubbers based on styrene butadiene rubber according to the relaxation index, compressive stress and the coefficient of radiation resistance in terms of relative elongation increases three times compared to carbon blacks P803. Similarly, dependencies were obtained in rubbers based on other types of rubbers, including nitrile butadiene rubbers, possessing low radiation resistance due to the increased tendency to structuring. The findings indicate that the carbon-containing material is an effective filler for increasing the radiation resistance of industrial rubber goods and cables, operated in the environment of ionizing radiation.
Formation of environmental safety of the environment as a result of the activities of the oil refining enterprise
Authors: Oznobikhina L A 
Published: July 2021

Abstract
The socio-political aspect of considering the environmental problems of the operation of oil refineries is associated with solving environmental problems on a scale of all mankind in the presence of various social systems. Oil refining processes pose a danger to the habitat of the living world, as the atmosphere, hydrosphere, lithosphere are polluted. To prevent and reduce the environmental load on the environment, it is necessary to introduce environmental management methods in oil refining, to conduct economic activities within the capacity of ecosystems on the basis of the massive introduction of energy and resource-saving technologies.
Fuel and energy complex of Yakutia: environmental aspects
Authors: Savvinov Grigory N , Velichenko Valery V 
Published: July 2021

Abstract
The article discusses the issues of ecology of enterprises of the fuel and energy complex of Yakutia (FEC). The research was carried out on the basis of the study of the stock materials of the Research Institute of Applied Ecology of the North of the NEFU, literature sources and a detailed analysis of departmental materials of the profile ministries of the Republic of Sakha (Yakutia). The data on emissions into the atmosphere and discharges into watercourses carried out by the enterprises of the fuel and energy complex are presented. The development of mineral deposits in Yakutia is carried out mainly by the open method with the massive use of drilling and blasting operations, as a result of which dust and gas emissions into the atmosphere and the removal of finely dispersed clay material into water bodies occur. A serious source of emission of pollutants into the atmosphere among energy enterprises is housing and communal services, the emission from which comes practically without purification. The analysis of the materials made it possible to establish that the activities of enterprises in the fuel and energy complex as a whole comply with the requirements of the environmental legislation of the Russian Federation, and the impact of enterprises on the ecological state of the atmosphere of the republic is of a local nature. The quality of the environment in the Republic of Sakha (Yakutia) is assessed as satisfactory.
The low and high temperature thermoelectric properties of Yb3Si5
Authors: Ahmed Fahim , Valenta Jaroslav , Tsujii Naohito , Hussain Ahmad , Jabeen Nawishta , Mori Takao 
Published: July 2021

Abstract
Silicides have been of great interest for thermoelectric applications due to their abundant elements as well as thermal and chemical stability. In this paper, we examined the thermoelectric properties of Yb3Si5 polycrystalline samples in a wide temperature range from 10 to 800 K. The temperature dependence of the Seebeck coefficient was successfully analyzed by assuming a narrow 4f quasi-particle band, indicating the intermediate valence state of Yb2+-Yb3+ is responsible for the high power factor. A very large maximum power factor of ∼ 4.70 mWm−1K−2 was observed at 72 K and room temperature value ∼ 1.56 mWm−1K−2 for Yb3Si5. These results shows that Yb-Si compounds have large potential to be used as low temperature TE applications in the future. We also studied the Co-doping effect in Yb3Si5, namely, Yb3Co
x
Si5−x
where x = 0, 0.1, 0.15, 0.20 and investigated their thermoelectric properties. While powder X-ray diffraction analysis confirmed all main peaks indexed to Yb3Si5 phase, SEM and EDX analyses revealed that Co is precipitated as metal particles, forming a composite material with Yb3Si5 phase. Thermoelectric properties of the Co-doped samples are also reported.
Experimental advances in charge and spin transport in chemical vapor deposited graphene
Authors: Mishra H , Panda J , Ramu M , Sarkar T , Dayen J-F , Belotcerkovtceva Daria , Kamalakar M Venkata 
Published: July 2021

Abstract
Despite structural and processing-induced imperfections, wafer-scale chemical vapor deposited (CVD) graphene today is commercially available and has emerged as a versatile form that can be readily transferred to desired substrates for various nanoelectronic and spintronic applications. In particular, over the past decade, significant advancements in CVD graphene synthesis methods and experiments realizing high-quality charge and spin transport have been achieved. These include growth of large-grain graphene, new processing methods, high-quality electrical transport with high-carrier mobility, micron-scale ballistic transport, observations of quantum and fractional quantum Hall effect, as well as the spintronic performance of extremely long spin communication over tens of micrometers at room temperature with robust spin diffusion lengths and spin lifetimes. In this short review, we discuss the progress in recent years in the synthesis of high-quality, large-scale CVD graphene and improvement of the electrical and spin transport performance, particularly towards achieving ballistic and long-distance spin transport that show exceptional promise for next-generation graphene electronic and spintronic applications.
Unifying system identification and biomechanical formulations for the estimation of muscle, tendon and joint stiffness during human movement
Authors: Cop Christopher P , Cavallo Gaia , van ’t Veld Ronald C , FJM Koopman Bart , Lataire John , Schouten Alfred C , Sartori Massimo 
Published: July 2021

Abstract

In vivo joint stiffness estimation during time-varying conditions remains an open challenge. Multiple communities, e.g. system identification and biomechanics, have tackled the problem from different perspectives and using different methods, each of which entailing advantages and limitations, often complementary. System identification formulations provide data-driven estimates of stiffness at the joint level, while biomechanics often relies on musculoskeletal models to estimate stiffness at multiple levels, i.e. joint, muscle, and tendon. Collaboration across these two scientific communities seems to be a logical step toward a reliable multi-level understanding of joint stiffness. However, differences at the theoretical, computational, and experimental levels have limited inter-community interaction. In this article we present a roadmap to achieve a unified framework for the estimation of time-varying stiffness in the composite human neuromusculoskeletal system during movement. We present our perspective on future developments to obtain data-driven system identification and musculoskeletal models that are compatible at the theoretical, computational, and experimental levels. Moreover, we propose a novel combined closed-loop paradigm, in which reference estimates of joint stiffness via system identification are decomposed into underlying muscle and tendon contribution via high-density-electromyography-driven musculoskeletal modeling. We highlight the need for aligning experimental requirements to be able to compare both joint stiffness formulations. Unifying both biomechanics’ and system identification’s formulations is a necessary step for truly generalizing stiffness estimation across individuals, movement conditions, training and impairment levels. From an application point of view, this is central for enabling patient-specific neurorehabilitation therapies, as well as biomimetic control of assistive robotic technologies. The roadmap we propose could serve as an inspiration for future collaborations across broadly different scientific communities to truly understand joint stiffness bio- and neuromechanics.
Operation and performance of the 4H-SiC junctionless FinFET
Authors: Naydenov K , Donato N , Udrea F 
Published: July 2021

Abstract
This work presents a comprehensive study on the behaviour and operation of a vertical 1.2 kV 4H-SiC junctionless power FinFET. The increased bulk conduction in the channel of this topology may bring reductions in the channel resistance compared to trench MOSFETs, whose performance is limited by the high interface state density. For this purpose, finite element (FE) simulations are used to examine the operation of this device. It is hence demonstrated that the junctionless FinFET can attain a high average channel drift mobility well above 100 cm2/(Vs), leaving the resistance to be determined by the drift and substrate regions. This allows the FinFET to turn on and reach its steady state current using a much (> 3x) smaller gate overdrive than standard designs. On the other hand, however, the overly high field in the gate oxide, the lack of an efficient mechanism for hole extraction, and the low threshold voltage can cause significant reliability issues. Furthermore, it is shown that the high input capacitance of the FinFET can limit its switching speed to slower levels than in standard trench MOSFETs, which raises the need for further development of the original design proposed for vertical GaN devices. In this context, it is demonstrated that the addition of a p-shield below the trenches can alleviate the off-state reliability issues and increase the speed, while still maintaining a competitive R

on
∼ 2mΩ cm2 even without the use of n-JFET enhancement doping.
Simplicial contagion in temporal higher-order networks
Authors: Chowdhary Sandeep , Kumar Aanjaneya , Cencetti Giulia , Iacopini Iacopo , Battiston Federico 
Published: July 2021

Abstract
Complex networks represent the natural backbone to study epidemic processes in populations of interacting individuals. Such a modeling framework, however, is naturally limited to pairwise interactions, making it less suitable to properly describe social contagion, where individuals acquire new norms or ideas after simultaneous exposure to multiple sources of infections. Simplicial contagion has been proposed as an alternative framework where simplices are used to encode group interactions of any order. The presence of these higher-order interactions leads to explosive epidemic transitions and bistability. In particular, critical mass effects can emerge even for infectivity values below the standard pairwise epidemic threshold, where the size of the initial seed of infectious nodes determines whether the system would eventually fall in the endemic or the healthy state. Here we extend simplicial contagion to time-varying networks, where pairwise and higher-order simplices can be created or destroyed over time. By following a microscopic Markov chain approach, we find that the same seed of infectious nodes might or might not lead to an endemic stationary state, depending on the temporal properties of the underlying network structure, and show that persistent temporal interactions anticipate the onset of the endemic state in finite-size systems. We characterize this behavior on higher-order networks with a prescribed temporal correlation between consecutive interactions and on heterogeneous simplicial complexes, showing that temporality again limits the effect of higher-order spreading, but in a less pronounced way than for homogeneous structures. Our work suggests the importance of incorporating temporality, a realistic feature of many real-world systems, into the investigation of dynamical processes beyond pairwise interactions.
Crossing Birth-Weight–Specific Mortality Curves: How a Puzzling Clinical Observation Led to an Important Advance in Epidemiologic Methods
Authors: Klebanoff Mark A 
Published: July 2021

Abstract
Throughout the second half of the 20th century, clinicians noted that although African-American neonates were more likely than White neonates to weigh less than 2,500 g at birth (low birth weight), among low–birth-weight infants African Americans were more likely than Whites to survive. However, when born at normal weight, African-American infants were substantially less likely to survive. The observation generated much physiological speculation, and several clever mathematical manipulations were devised to “uncross the mortality curves.” With the development and dissemination of directed acyclic graphs in the early 2000s, methodologists focusing on perinatal epidemiology showed graphically, in an early use of directed acyclic graphs, that birth weight was a “collider” and that controlling for birth weight, whether by regression, stratification, or restriction, introduced confounding of the race-mortality association by all unmeasured common causes of birth weight and mortality. These investigations showed that the crossing curves could be explained as an artifact of a conceptually flawed analysis. These results have applicability beyond perinatal epidemiology, including applicability to the “obesity paradox.”
pKPDB: a protein data bank extension database of pKa and pI theoretical values
Authors: Reis Pedro B P S , Clevert Djork-Arné , Machuqueiro Miguel 
Published: July 2021

Abstract

Summary
pKa values of ionizable residues and isoelectric points of proteins provide valuable local and global insights about their structure and function. These properties can be estimated with reasonably good accuracy using Poisson–Boltzmann and Monte Carlo calculations at a considerable computational cost (from some minutes to several hours). pKPDB is a database of over 12 M theoretical pKa values calculated over 120k protein structures deposited in the Protein Data Bank. By providing precomputed pKa and pI values, users can retrieve results instantaneously for their protein(s) of interest while also saving countless hours and resources that would be spent on repeated calculations. Furthermore, there is an ever-growing imbalance between experimental pKa and pI values and the number of resolved structures. This database will complement the experimental and computational data already available and can also provide crucial information regarding buried residues that are under-represented in experimental measurements.

Availability and implementation
Gzipped csv files containing p Ka and isoelectric point values can be downloaded from https://pypka.org/pKPDB. To query a single PDB code please use the PypKa free server at https://pypka.org. The pKPDB source code can be found at https://github.com/mms-fcul/pKPDB.

Supplementary information
Supplementary data are available at Bioinformatics online.
Single-dose mRNA Vaccine Effectiveness Against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Including Alpha and Gamma Variants: A Test-negative Design in Adults 70 Years and Older in British Columbia, Canada
Authors: Skowronski Danuta M , Setayeshgar Solmaz , Zou Macy , Prystajecky Natalie , Tyson John R , Galanis Eleni , Naus Monika , Patrick David M , Sbihi Hind , El Adam Shiraz , Henry Bonnie , Hoang Linda M N , Sadarangani Manish , Jassem Agatha N , Krajden Mel 
Published: July 2021

Abstract

Background
Randomized-controlled trials of messenger RNA (mRNA) vaccine protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) included relatively few elderly participants. We assess single-dose mRNA vaccine effectiveness (VE) in adults ≥ 70 years old in British Columbia, Canada, where second doses were deferred by up to 16 weeks and where a spring 2021 wave uniquely included codominant circulation of Alpha (B.1.1.7) and Gamma (P.1) variants of concern (VOC).

Methods
Analyses included community-dwelling adults ≥ 70 years old with specimen collection between 4 April (epidemiological week 14) and 1 May (week 17) 2021. Adjusted VE was estimated by test-negative design. Cases were reverse-transcription polymerase chain reaction (RT-PCR) test-positive for SARS-CoV-2, and controls were test-negative. Vaccine status was defined by receipt of a single-dose ≥ 21 days before specimen collection, but a range of intervals was assessed. Variant-specific VE was estimated against viruses genetically characterized as Alpha, Gamma or non-VOC lineages.

Results
VE analyses included 16 993 specimens: 1226 (7%) test-positive cases and 15 767 test-negative controls. Of 1131 (92%) genetically characterized viruses, 509 (45%), 314 (28%), and 276 (24%) were Alpha, Gamma, and non-VOC lineages, respectively. At 0–13 days postvaccination, VE was negligible at 14% (95% confidence interval [CI], 0–26) but increased from 43% (95% CI, 30–53) at 14–20 days to 75% (95% CI, 63–83) at 35–41 days postvaccination. VE at ≥ 21 days postvaccination was 65% (95% CI, 58–71) overall: 72% (95% CI, 58–81), 67% (95% CI, 57–75), and 61% (95% CI, 45–72) for non-VOC, Alpha, and Gamma variants, respectively.

Conclusions
A single dose of mRNA vaccine reduced the risk of SARS-CoV-2 by about two-thirds in adults ≥ 70 years old, with protection only minimally reduced against Alpha and Gamma variants.