bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Selective Electrocatalytic CO2 Reduction to Methanol on Iridium Dioxide with CO* Spectators
Authors: Zhao He , Zhu Haiyan , Feng Yifan , Zhao Qinfu , Suo Bingbing , Zou Wenli , Han Huixian , Zhai Gaohong , Jiang Zhenyi , Song Qi , Li Yawei
Published: December 2020

Iridium dioxide has emerged as a promising anode family for electrocatalytic reduction of CO2. Herein, the catalytic mechanism of CO2 reduction reaction (CO2RR) on the IrO2 (110) electrocatalyst model has been assessed using density functional theory (DFT) calculations. The CO* spectator on the IrO2 (110) is the crucial factor, which directly affects the binding free energy of the reaction intermediates by means of the different ratios of CO* spectator models. Our results showed that the CO* spectator may have a great promotion effect on the methanol production, and it always maintains low sensitivity on the CO2 reduction to methane reaction. The onset potentials for reducing to methanol and methane are −0.32 V‐RHE and −0.68 V‐RHE, respectively, at a CO* coverage of 50 %, which means that providing an appropriate CO* coverage can improve the selectivity of CO2 catalytic reduction to methanol tremendously. It is worth noting that the intermediate CH3O*+OH*, which plays a vital role in the major pathways to produce methanol and methane, is a branch point that led to the formation of two products. Although both subsequent protonation processes are exothermic, the path to methanol production is more favorable than that of CH4 formation. These results demonstrate that iridium dioxide should be a good CO2RR catalyst, and the CO* spectator also exhibits an enhanced effect on the selectivity of CO2 reduced to alcohol products.
Automatic sparse principal component analysis
Authors: Park Heewon , Yamaguchi Rui , Imoto Seiya , Miyano Satoru
Published: December 2020

The wide availability of computers enables us to accumulate a huge amount of data, thus effective tools to extract information from the huge volume of data have become critical. Principal component analysis (PCA) is a useful and traditional tool for dimensionality reduction of massive high‐dimensional datasets. Recently, sparse principal component (PC) loading estimation based on L1‐type regularization has drawn a large amount of attention. Although sparse PCA makes interpretation easily and performs dimension reduction without disturbance from noisy features, the existing studies on sparse PCA were based on an arbitrary number of PCs without any statistical justification. We propose a novel method, called as automatic sparse PCA, which can perform PC selection and sparse PC loading estimation, simultaneously. For PC selection, we first develop sparse singular value decomposition (sparse SVD), then incorporate sparsity into PC loading estimation. The proposed method enables us to perform dimension reduction and PC loading estimation, simultaneously. Furthermore, we can perform PCA without disturbance from noisy features. It can be seen through Monte Carlo experiments that the proposed automatic sparse PCA outperforms sparse structure identification and reconstructing data based on low‐dimensional projection. The proposed method is also applied to a number of real datasets and it can be also seen that our method achieves effectiveness for estimation accuracy and interpreting PCA results.
Sensitivity analysis of mechanical properties and ductile/brittle behaviors in aluminum‐silicon alloy to loading rate and nano‐particles, considering interaction effects
Authors: Azadi Mohammad , Zomorodipour Mohammad , Fereidoon Abdoulhossein
Published: December 2020

Aluminum‐silicon alloys have been widely used in automotive industries. To know mechanical properties of such materials is essential for engineers to have a superior design for components. Therefore, in this article, the sensitivity analysis of mechanical and fracture features in the aluminum alloy has been performed to find the effect of the loading rate and nano‐particles. For this objective, tensile tests were performed on casting standard specimens. Then, obtained experimental data were analyzed by the Minitab software, using the factorial method. In addition, the interaction between the effect of the loading rate and the addition of nano‐particles, on mechanical properties and ductile/brittle behaviors, was also investigated. Obtained results indicated that the yield stress, the elastic modulus and the elongation were sensitive to the interaction of both factors (the multiply of the nano‐particle addition and the loading rate). Besides, the fracture surface illustrated that by increasing the loading rate and the addition of nano‐particles, the brittleness of the material increased.
Shock tube data processing tools using open source hardware and software platforms
Authors: Thirumalesh K. , Raju Salgeri Puttaswamy , Somashekarappa Hiriyur Mallaiah , Swaroop Kumaraswamy
Published: December 2020

To cater the need of specific shock‐tube data acquisition and processing system, a low cost open‐source alternative has been developed and presented in this paper. Using easily available open‐source hardware and software platforms such as ARDUINO, a robust 5.3 MHz speed data acquisition system along with optimized shock tube data processing software is designed and an indigenous shock tube data processing tool has been developed. This has been found to be 10 times less cost than the general‐purpose computing equipment available on the market, with a substantial reduction in shockwave data processing time and effort. The setup has been tested with the different diaphragms producing shockwaves of different Mach numbers. The experimental results are compared with the theoretical values obtained using normal shock relations and are found to be consistent with admissible error limits. This validates the design and construction of the device for scientific experiments.
Bromodomain‐containing protein 4 and its role in cardiovascular diseases
Authors: Li Liang , Xie Wei , Gui Yu , Zheng Xi‐Long
Published: December 2020

Bromodomain‐containing protein 4 (BRD4), a chromatin‐binding protein, is involved in the development of various tumors. Recent evidence suggests that BRD4 also plays a significant role in cardiovascular diseases, such as ischemic heart disease, hypertension, and cardiac hypertrophy. This review summarizes the roles of BRD4 as a potential regulator of various pathophysiological processes in cardiovascular diseases, implicating that BRD4 may be a new therapeutic target for cardiovascular diseases in the future.
How effective is a mask in preventing COVID‐19 infection?
Authors: Wang Yuxin , Deng Zicheng , Shi Donglu
Published: December 2020

The main clinical characteristics of COVID‐19 are respiratory symptoms that can lead to serious cardiovascular damages and severe worsening of other medical conditions. One of the major strategies in preparedness and response to COVID 19 is effective utilization of personal protective equipment (PPE) among which the masks of different kinds are on the top of the list especially for activities in the public places. However, the underlying mechanisms of masks in preventing virus transmission have not been well identified and the current experimental data still show inconsistent outcomes that may mislead the public. For instance, the early understanding of the mask functions was limited especially in the escalating phase of the COVID 19 pandemic, resulting in quite controversial remarks on masks. Although extensive studies in mask functions have been carried out ever since the COVID‐19 outbreaks, most of the investigations appear to have focused on exhalation isolation of individuals who may have been infected with the disease. Less emphasis was laid on inhalation protection from virus transmission, an important aspect that undergirds the public health policies and protective strategies. This review provides the most up‐to‐date information on the transmission modes of COVID‐19 virus in terms of droplets and aerosols. The roles of masks in disease prevention and transmission reduction are evaluated on various types, structures and functions. More important, both aspects of exhalation isolation and inhalation protection are discussed based on virus transmission modes and the effectiveness of different types of masks under varied environmental conditions.
Efficient modelling of flexible cable-pulley systems
Authors: Spiegelhauer Markus , Schlecht Berthold
Published: December 2020

This article proposes a universal procedure for efficiently modelling the flexible behaviour of pre-stressed cables, guided by multiple pulleys. Such cable-pulley systems usually connect various structural components, which often feature additional flexibility. One concern in holistic system analyses is to correctly describe the elasticity of the entire assembly for one particular spatial configuration. This can be achieved in terms of a linear stiffness matrix that accounts for the kinematics of the assembly. In this article, parametric stiffness matrices for arbitrary cable-pulley arrangements are derived. A reduction scheme is used to facilitate the integration of the derived stiffness matrix into superordinate finite element models. The method is validated with a non-linear finite element model and applied to a complex hoisting cable system connecting multiple large steel structures.
Partial Identification of Latent Correlations with Binary Data
Authors: Grønneberg Steffen , Moss Jonas , Foldnes Njål
Published: December 2020

The tetrachoric correlation is a popular measure of association for binary data and estimates the correlation of an underlying normal latent vector. However, when the underlying vector is not normal, the tetrachoric correlation will be different from the underlying correlation. Since assuming underlying normality is often done on pragmatic and not substantial grounds, the estimated tetrachoric correlation may therefore be quite different from the true underlying correlation that is modeled in structural equation modeling. This motivates studying the range of latent correlations that are compatible with given binary data, when the distribution of the latent vector is partly or completely unknown. We show that nothing can be said about the latent correlations unless we know more than what can be derived from the data. We identify an interval constituting all latent correlations compatible with observed data when the marginals of the latent variables are known. Also, we quantify how partial knowledge of the dependence structure of the latent variables affect the range of compatible latent correlations. Implications for tests of underlying normality are briefly discussed.
Population Grids for Analysing Long-Term Change in Ethnic Diversity and Segregation
Authors: Catney Gemma , Lloyd Christopher D.
Published: December 2020

Changes in the spatial patterns of ethnic diversity and residential segregation are often highly localized, but inconsistencies in geographical data units across different time points limit their exploration. In this paper, we argue that, while they are often over-looked, population grids provide an effective means for the study of long-term fine-scale changes. Gridded data represent population structures: there are gaps where there are no people, and they are not (unlike standard zones) based on population distributions at any one time point. This paper uses an innovative resource,PopChange, which provides spatially fine-grained (1 km by 1 km) gridded data on country of birth (1971–2011) and ethnic group (1991–2011). These data enable insight into micro-level change across a long time period. Exploring forty years of change over five time points, measures of residential ethnic diversity and segregation are employed here to create a comprehensive ‘atlas’ of ethnic neighbourhood change across the whole of Britain. Four key messages are offered: (1) as Britain’s ethnic diversity has grown, the spatial complexity of this diversity has also increased, with greater diversity in previously less diverse spaces; (2) ethnic residential segregation has steadily declined at this micro-scale; (3) as neighbourhoods have become more diverse, they have become more spatially integrated; (4) across the whole study period, the most dynamic period of change was between 2001 and 2011. While concentrating on Britain as a case study, the paper explores the potential offered by gridded data, and the methods proposed to analyse them, for future allied studies within and outside this study area.
A framework for enhanced decision-making in aircraft conceptual design optimisation under uncertainty
Authors: Bianchi D.H.B. Di , Sêcco N.R. , Silvestre F.J.
Published: December 2020

This paper presents a framework to support decision-making in aircraft conceptual design optimisation under uncertainty. Emphasis is given to graphical visualisation methods capable of providing holistic yet intuitive relationships between design, objectives, feasibility and uncertainty spaces. Two concepts are introduced to allow interactive exploration of the effects of (1) target probability of constraint satisfaction (price of feasibility robustness) and (2) uncertainty reduction through increased state-of-knowledge (cost of uncertainty) on design and objective spaces. These processes are tailored to handle multi-objective optimisation problems and leverage visualisation techniques for dynamic inter-space mapping. An information reuse strategy is presented to enable obtaining multiple robust Pareto sets at an affordable computational cost. A case study demonstrates how the presented framework addresses some of the challenges and opportunities regarding the adoption of Uncertainty-based Multidisciplinary Design Optimisation (UMDO) in the aerospace industry, such as design margins policy, systematic and conscious definition of target robustness and uncertainty reduction experiments selection and prioritisation.
ATCO radar training assessment and flight efficiency: the correlation between trainees’ scores and fuel consumption in real-time simulations
Authors: Rogošić T. , Juričić B. , Aybek Çetek F. , Kaplan Z.
Published: December 2020

Air traffic controller training is highly regulated but lacks prescribed common assessment criteria and methods to evaluate trainees at the level of basic training and consideration of how trainees in fluence flight efficiency. We investigated whether there is a correlation between two parameters, viz. the trainees’ assessment score and fuel consumption, obtained and calculated after real-time human-in-the-loop radar simulations within the ATCOSIMA project. Although basic training assessment standards emphasise safety indicators, it was expected that trainees with higher assessment scores would achieve better flight efficiency, i.e. less fuel consumption. However, the results showed that trainees’ assessment scores and fuel consumption did not correlate in the expected way, leading to several conclusions.
Ice stream subglacial access for ice-sheet history and fast ice flow: the BEAMISH Project on Rutford Ice Stream, West Antarctica and initial results on basal conditions
Authors: Smith A. M. , Anker P. G. D. , Nicholls K. W. , Makinson K. , Murray T. , Rios-Costas S. , Brisbourne A. M. , Hodgson D. A. , Schlegel R. , Anandakrishnan S.
Published: December 2020

Three holes were drilled to the bed of Rutford Ice Stream, through ice up to 2154 m thick, to investigate the basal processes and conditions associated with fast ice flow and the glacial history of the West Antarctic Ice Sheet. A narrative of the drilling, measuring and sampling activities, as well as some preliminary results and initial interpretations of subglacial conditions, is given. These were the deepest subglacial access holes ever drilled using the hot-water drilling method. Samples of bed and englacial sediments were recovered, and a number of instruments were installed in the ice column and the bed. The ice–bed interface was found to be unfrozen, with an existing, well-developed subglacial hydrological system at high pressure, within ~1% of the ice overburden. The bed itself comprises soft, water-saturated sediments, consistent with previous geophysical interpretations. Englacial sediment quantity varies significantly between two locations ~2 km apart, and possibly over even shorter (~20 m) distances. Difficulties and unusual observations encountered while connecting to the subglacial hydrological system in one hole possibly resulted from the presence of a large clast embedded in the bottom of the ice.
Proof of a conjecture of Galvin
Authors: Raghavan Dilip , Todorcevic Stevo
Published: December 2020

We prove that if the set of unordered pairs of real numbers is coloured by finitely many colours, there is a set of reals homeomorphic to the rationals whose pairs have at most two colours. Our proof uses large cardinals and verifies a conjecture of Galvin from the 1970s. We extend this result to an essentially optimal class of topological spaces in place of the reals.
Physical Attraction Scale — Short Version: Cross-Cultural Validation
Authors: Karandashev Victor , Evans Nicholas D. , Zarubko Elena , Neto Félix , Evans Makesha , Artemeva Veronika , Morgan Kai Andito Damali , Feybesse Cyrille , Surmanidze Lali
Published: December 2020

Physical attraction is an important dimension of both romantic and companionate relationship of partners. This article presents a comprehensive cross-cultural validation of the short version of the Physical Attraction Scale (PAS-S) scale — the first and only multidimensional measure of physical attraction available for research and practice. The initial development of the scale was completed in a multisite study conducted with a large sample of university students, largely from the midwest and southeast of the United States. Results demonstrated a two-dimensional factor structure, excellent reliability, and evidence of content, convergent and discriminant validity. The following cross-cultural studies, which used the PAS-S, confirmed its robust factor structure, validity and reliability in the samples from 10 cultural regions in six countries. Therefore, this short version of the PAS-S can be recommended for cross-cultural practice and research. The versions of the scale in English, French, Portuguese, Russian and Georgian are provided in appendices. Based on the results of cross-cultural validation, authors recommend the PAS-S for research purposes and practical use in counselling and therapy. The scale provides a short and informative measure of (1) how a person feels attraction to their partner in close relationships and (2) which aspects of attraction are problematic.
Asset Revaluation and the Existential Politics of Climate Change
Authors: Colgan Jeff D. , Green Jessica F. , Hale Thomas N.
Published: December 2020

Whereas scholars have typically modeled climate change as a global collective action challenge, we offer a dynamic theory of climate politics based on the present and future revaluation of assets. Climate politics can be understood as a contest between owners of assets that accelerate climate change, such as fossil fuel plants, and owners of assets vulnerable to climate change, such as coastal property. To date, obstruction by “climate-forcing” asset holders has been a large barrier to effective climate policy. But as climate change and decarbonization policies proceed, holders of both climate-forcing and “climate-vulnerable” assets stand to lose some or even all of their assets' value over time, and with them, the basis of their political power. This dynamic contest between opposing interests is likely to intensify in many sites of political contestation, from the subnational to transnational levels. As it does so, climate politics will become increasingly existential, potentially reshaping political alignments within and across countries. Such shifts may further undermine the Liberal International Order (LIO); as countries develop pro-climate policies at different speeds and magnitudes, they will have incentives to diverge from existing arrangements over trade and economic integration.
Proactive Capital Structure Adjustments: Evidence from Corporate Filings
Authors: Korteweg Arthur , Schwert Michael , Strebulaev Ilya A.
Published: December 2020

We use new hand-collected data from corporate filings to study the drivers of corporate capital structure adjustment. Classifying firms by their adjustment frequencies, we reveal previously unknown patterns in their reasons for financing and the financial instruments used. Some are consistent with existing theory, whereas others are understudied. Many leverage changes are outside of the firm’s control (e.g., executive option exercise) or incur negligible adjustment costs (e.g., credit-line usage). This implies a lower frequency of proactive leverage adjustments than indicated by prior research using accounting data, suggesting that costs of adjustment are higher, or the benefits lower, than previously thought.
THE NEW LEGAL ANTI-POSITIVISM
Authors: Dindjer Hasan
Published: December 2020

According to a recent wave of work by legal anti-positivists, legal norms are a subset of moral norms. This striking “one-system” view of law has rapidly become the dominant form of anti-positivism, but its implications have so far been little tested. This article argues that the one-system view leads systematically to untenable conclusions about what legal rights and obligations we have. For many clear legal norms, the view lacks the resources to explain the existence of corresponding moral norms. And its criteria for distinguishing legal norms within morality imply an under- or over-inclusive set of legal norms. I stress the special difficulties that apply beyond obligations, in the case of privileges and powers, and I show that the view's problems do not only—or mainly—concern egregiously unjust law, or indeed morally defective law at all. I close with reflections on legal normativity and the prospects for different forms of anti-positivism.
The Patriotic Turn in Russia: Political Convergence of the Russian Orthodox Church and the State?
Authors: Shakhanova Gaziza , Kratochvíl Petr
Published: December 2020

Following two decades of a state-supported patriotic campaign, the Russian Orthodox Church has dramatically increased its presence in the public sphere: in the Armed Forces, in public schools and universities, and even in retirement houses and prisons. The Church's recent activities seem to have no territorial limits: they reach up to the space station “Mir” and the Russian Antarctic Station, as well as the (Russian) Orthodox believers in 62 states. Using a critical discourse analysis of the speeches of top Church leaders as our main methodological tool, our research explores the Church's policies on patriotism and patriotic education, its re-interpretation of historical memory, and the role of the Church in Russian politics. We try to show that while the Church's agenda and approach to politics are idiosyncratic, the Church has become a key actor with an increasingly important political role.
The readiness of industry for a transformative recovery from COVID 19
Authors: Fankhauser Sam , Kotsch Raphaela , Srivastav Sugandha
Published: December 2020

Non-technical summary

Many countries are committed to emerge from COVID 19 on a more sustainable environmental footing. Here we explore what such a structurally transformative recovery would mean for the manufacturing sector of 14 major economies. We find that all countries have zero-carbon growth opportunities post-COVID and comparative advantages in some sectors, but industrialised countries and the East Asian economies, especially South Korea, appear best positioned, thanks a push in low-carbon innovation that predates the pandemic.
In‐situ Mass Balance Estimates Offshore Costa Rica
Authors: Edwards J. , Kluenser Jared , Silver Eli , Lauer Rachel , Bangs Nathan , Boston Brian
Published: December 2020

The Costa Rican convergent margin has been considered a type erosive margin, with erosional models suggesting average losses up to −153 km3/km/m.y. However, three‐dimensional (3D) seismic reflection and Integrated Ocean Drilling Program data collected offshore the Osa Peninsula images accretionary structures and vertical motions that conflict with the forearc basal erosion model. Here we integrate such data to do an in‐situ accounting of material transfer at the plate boundary across the outermost 10 km of the forearc, characterized by active and inactive megathrusts. Our in‐situ budget finds an approximate balance between sediment recycling via accretion and underplating, 0.7–2.3 km3/km/m.y., and basal erosion, 0.7 km3/km/m.y., while subducting sediment volumes, 7.8 km3/km/m.y., greatly outpace either material transfer volumes. These budget results differ significantly from published estimates based on simple proxies of trench axis deflection and slope subsidence. These budget results are the summation of thin incoming hemipelagic sediments that variably accrete along the deformation front, underplating of hemipelagic sediments on the upthrown‐side and basal erosion on the downthrown‐side of active plate bending faulting landward of the trench axis, and sediment subduction primarily composed of pelagic sediments.
Effects of microfluidization and thermal treatment on the characterization and digestion of curcumin loaded protein–polysaccharide–tea saponin complex nanoparticles
Authors: Wei Yang , Wang Chao , Liu Xin , Liao Wenyan , Zhang Liang , Chen Shuai , Liu Jinfang , Mao Like , Yuan Fang , Gao Yanxiang
Published: December 2020

Microfluidization (50–150 MPa) and thermal treatment (45–85 °C) were applied to modulate the stability, molecular interaction and microstructure of zein–proplyene glycol alginate (PGA)–tea saponin (TS) complex nanoparticles for delivery of curcumin.
Autonomous operation of 3D DNA walkers in living cells for microRNA imaging
Authors: Hu Hui , Zhou Fu , Wang Baojuan , Chang Xin , Dai Tianyue , Tian Ruifen , Wan Yifei , Wang Xiayan , Wang Guangfeng
Published: December 2020

Three dimensional (3D) DNA walkers hold great potential in serving as an ideal candidate for signal transduction and amplification in bio-assays.
Ultra-flexible and rollable 2D-MoS2/Si heterojunction-based near-infrared photodetector via direct synthesis
Authors: Choi Jung-Min , Jang Hye Yeon , Kim Ah Ra , Kwon Jung-Dae , Cho Byungjin , Park Min Hyuk , Kim Yonghun
Published: December 2020

Flexible and rollable MoS2/Si photodetector reveals excellent high flexibility, rollability as well as durability under harsh bending conditions.
Vapor phase polymerized conducting polymer/MXene textiles for wearable electronics
Authors: Zheng Xianhong , Shen Jiakun , Hu Qiaole , Nie Wenqi , Wang Zongqian , Zou Lihua , Li Changlong
Published: December 2020

Vapor phase polymerized PEDOT/MXene textiles exhibited excellent electrochemical, Joule heating, electromagnetic interference (EMI) shielding, and strain sensing performance.
Polymer light-emitting electrochemical cells with ultralow salt content: performance enhancement through synergetic chemical and electrochemical doping actions
Authors: Hu Shiyu , Yeh Hung-Wei , Gao Jun
Published: December 2020

This work demonstrates that PLECs made with a low AgOTf salt concentration exhibit record luminance, efficiency, lifetime and response speed.
Copper-assisted oxidation of catechols into quinone derivatives
Authors: Gómez-Herrero Ana Cristina , Sánchez-Sánchez Carlos , Chérioux Frédéric , Martínez Jose Ignacio , Abad José , Floreano Luca , Verdini Alberto , Cossaro Albano , Mazaleyrat Estelle , Guisset Valérie , David Philippe , Lisi Simone , Martín Gago José Angel , Coraux Johann
Published: December 2020

An antioxidant catechol transforms following intramolecular redox reactions into highly reactive oxygen species, a semiquinone and a quinone, on copper.
Unraveling driving regimes for destabilizing concentrated emulsions within microchannels
Authors: Porto Santos Tatiana , Cejas Cesare M. , Cunha Rosiane Lopes , Tabeling Patrick
Published: December 2020

There are four regimes to the destabilization of concentrated emulsions: (i) coalescence, (ii) emulsion bursts, (iii) a simultaneous combination of the first two mechanisms; and (iv) compaction of droplet network that leads to fracture-like behavior.
On the benefit of inter‐operator cooperation in C‐RAN
Authors: Kim Donggu , Sung Ki Won , Koh Jeongwan , Kang Joonhyuk
Published: December 2020

Cooperation of co‐located mobile network operators can provide potential benefits for the capacity expansion without further densification of radio nodes. However, such benefits need to be scrutinised for coexisting cloud radio access network (C‐RAN) operators because the inter‐operator cooperation may compromise the superb interference coordination capability that each C‐RAN has. Furthermore, altering C‐RAN infrastructure for the cooperation incurs a high investment cost. In this paper, quantitative gain of inter‐operator coordination strategies is evaluated to provide the C‐RAN operators with a guideline on their cooperation decisions. The coordination strategies encompass dynamic user association and the spectrum sharing which aim at maximising the total user throughput. A heuristic algorithm is proposed that reduces the computational burden of the coordination significantly. Numerical results suggest that the inter‐operator cooperation is beneficial particularly when the network size of each operator tends to be highly asymmetric. It is also verified that the users who belong to smaller network attain more coordination gains.
MIMO channel estimation with arbitrary angle of arrival incident power spectrum for wireless communications
Authors: Zhou Jie , Wang Xueying , Jiang Hao , Sasaki Shigenobu , Shao Genfu
Published: December 2020

This study proposes an approximate algorithm for the arbitrary angle of arrival (AoA) incident power spectrum in wireless environments. The approach expands approximate algorithms for small angles to the large‐angle AoA PDF. To achieve this, the fading correlation of wireless channels is calculated and derived for various theoretical fittings and measured data. Then, the multiple‐input multiple‐output (MIMO) channel model is reconstructed for special environments using spatial fading correlation (SFC). Following this, the approximate algorithm and its complexity are investigated in depth in the SFC of multi‐antenna arrays with small AoA angles under uniform, Gaussian, and Laplacian distributions, which can function in macrocell and microcell environments. Further, the closed form formulas for SFC are derived for the small angle spread of incident signals. The formulas are extended to simulate these cases with large angle spreads, which result in an increasing calculation complexity, particularly for the actual measured results. The selection of the number of samples and the weighting coefficient in the large angle spreads and its fitting accuracy are considered in detail. Based on this relationship, the properties of the temporal correlation and channel of the MIMO uniform linear array are studied and discussed.
Shaped offset 8PSK and coded shaped offset 8PSK with improved spectrum efficiency for satellite communication
Authors: Liu Yue , Cao Ning , Mao Minghe , Li Gang
Published: December 2020

The development of satellite communication (SATCOM) puts forward demanding requirements for the modulation methods' spectral efficiency (SE) which is mainly subject to the pulse shaping and the utilisation of signal space. To date, there has rare consideration on the modification of high order phase shift keying (HOPSK) to gain higher SE in this literature. In this work, shaped offset 8PSK (SO8PSK) is developed which splits 8PSK bit transmission into three offset paths and then loads the shaping pulse onto them. The obtained modulation with continuous constrained phase and constant envelope is shown to increase the SE compared to 8PSK by about 43% and is applicable for the nonlinear and band‐limited SATCOM environment. To address the HOPSK inherent complexity, a simplified receiver is provided to reduce about two‐third matched filters. Additionally, the iterative encoding of SO8PSK is presented and it is used as the inner code of serial concatenated coding (SCC) . This modification method can be seen as a starting point to the better use of HOPSK for SATCOM.
A new blind image conversion complexity metric for intelligent CMOS image sensors
Authors: Elmezayen Mohamed R. , Ay Suat U.
Published: December 2020

Many algorithms have been developed for complementary metal–oxide–semiconductor (CMOS) image sensors to speed up analogue‐to‐digital (A‐to‐D) conversion of captured images. However, there is no objective blind‐image quality metric available to compare and quantify the quality and effectiveness of these speed‐up algorithms. In this work, we developed a blind‐image quality and complexity metric for this purpose. The proposed metric relies on counting the successive zeros in a code histogram. The proposed metric is called the conversion complexity metric (CCM). The CCM is designed to quantify how complex, and to predict how much time and power consuming a captured image is for A‐to‐D conversion, mainly by integrating (ramp) type A‐to‐D converter used in column‐parallel architectures of a CMOS image sensor (CIS). The proposed metric, CCM, is tested for linearity, monotonicity, and sensitivity to many types of introduced distortion. The CCM is compared with other no‐reference and full‐reference image quality and complexity metrics. It accomplished, for brightness change distortion, 99% linearity and 316% sensitivity, providing a computationally efficient blind‐image quality metric that no other metrics provide for CIS to intelligently adjust and optimise on‐chip analogue and digital signal processing.
Oort cloud Ecology
Authors: Portegies Zwart S.
Published: December 2020

We simulate the formation and evolution of Oort clouds around the 200 nearest stars (within ∼16 pc according to theGaiaDR2) database. This study is performed by numerically integrating the planets and minor bodies in orbit around the parent star and in the Galactic potential. The calculations start 1 Gyr ago and continue for 100 Myr into the future. In this time frame, we simulate how asteroids (and planets) are ejected from the vicinity of the stars and settle in an Oort cloud and how they escape the local stellar gravity to form tidal streams. A fraction of 0.0098 to 0.026 of the asteroids remain bound to their parent star. The orbits of these asteroids isotropize and circularize because of the influence of the Galactic tidal field and eventually form an Oort cloud between ∼104and ∼2 × 105au. We estimate that ≲6% of the nearby stars may have a planet in their Oort cloud. The majority of asteroids (and some of the planets) become unbound from their parent star to become free floating in the Galactic potential. These interstellar asteroids remain in a similar orbit around the Galactic center to their host star, forming dense streams of rogue interstellar asteroids and planets. The Solar System occasionally passes through such tidal streams, potentially giving rise to occasional close encounters with objects in this stream. Two recently discovered sources, 1I/(2017 Q3) ’Oumuamua and 2I/(2019 Q4) Borisov, may be such objects. Although the direction from which an individual object originated cannot easily be traced back to the original host, multiple such objects coming from the same source might help to identify their origin. Currently, the Solar System is in the bow or wake of the tidal stream of approximately ten of the nearby stars, which might contribute considerably to the interaction rate. Overall, we estimate that the local density of such leftovers from the planet-formation process contributes to a local density of 1.2 × 1014per pc−3, or ≳0.1 of the interstellar visitors originate from the obliterated debris disks of such nearby stars.
Size and structures of disks around very low mass stars in the Taurus star-forming region
Authors: Kurtovic N. T. , Pinilla P. , Long F. , Benisty M. , Manara C. F , Natta A. , Pascucci I. , Ricci L. , Scholz A. , Testi L.
Published: December 2020

Context. The discovery of giant planets orbiting very low mass stars (VLMS) and the recent observed substructures in disks around VLMS is challenging planet formation models. Specifically, radial drift of dust particles is a catastrophic barrier in these disks, which prevents the formation of planetesimals and therefore planets.

Aims. We aim to estimate if structures, such as cavities, rings, and gaps, are common in disks around VLMS and to test models of structure formation in these disks. We also aim to compare the radial extent of the gas and dust emission in disks around VLMS, which can give us insight about radial drift.

Methods. We studied six disks around VLMS in the Taurus star-forming region using ALMA Band 7 (~340 GHz) at a resolution of ~0.1″. The targets were selected because of their high disk dust content in their stellar mass regime.

Results. Our observations resolve the disk dust continuum in all disks. In addition, we detect the 12CO (J = 3−2) emission line in all targets and 13CO (J = 3−2) in five of the six sources. The angular resolution allows the detection of dust substructures in three out of the six disks, which we studied by using UV-modeling. Central cavities are observed in the disks around stars MHO 6 (M 5.0) and CIDA 1 (M 4.5), while we have a tentative detection of a multi-ringed disk around J0433. We estimate that a planet mass of ~0.1 MJup or ~0.4 MSaturn is required for a single planet to create the first gap in J0433. For the cavities of MHO 6 and CIDA 1, a Saturn-mass planet (~0.3 MJup) is required. The other three disks with no observed structures are the most compact and faintest in our sample, with the radius enclosing 90% of the continuum emission varying between ~13 and 21 au. The emission of 12CO and 13CO is more extended than the dust continuum emission in all disks of our sample. When using the 12CO emission to determine the gas disk extension Rgas, the ratio of Rgas∕Rdust in our sample varies from 2.3 to 6.0. One of the disks in our sample, CIDA 7, has the largest Rgas∕Rdust ratio observed so far, which is consistent with models of radial drift being very efficient around VLMS in the absence of substructures.

Conclusions. Given our limited angular resolution, substructures were only directly detected in the most extended disks, which represent 50% of our sample, and there are hints of unresolved structured emission in one of the bright smooth sources. Our observations do not exclude giant planet formation on the substructures observed. A comparison of the size and luminosity of VLMS disks with their counterparts around higher mass stars shows that they follow a similar relation.
Speed limits for radiation-driven SMBH winds
Authors: Luminari A. , Nicastro F. , Elvis M. , Piconcelli E. , Tombesi F. , Zappacosta L. , Fiore F.
Published: December 2020

Context.Ultra-fast outflows (UFOs) have become an established feature in analyses of the X-ray spectra of active galactic nuclei (AGN). According to the standard picture, they are launched at accretion disc scales with relativistic velocities, up to 0.3−0.4 times the speed of light. Their high kinetic power is enough to induce an efficient feedback on a galactic scale, possibly contributing to the co-evolution between the central supermassive black hole (SMBH) and the host galaxy. It is, therefore, of paramount importance to gain a full understanding of UFO physics and, in particular, of the forces driving their acceleration and the relation to the accretion flow from which they originate.

Aims.In this paper, we investigate the impact of special relativity effects on the radiative pressure exerted onto the outflow. The radiation received by the wind decreases for increasing outflow velocity,v, implying that the standard Eddington limit argument has to be corrected according tov. Due to the limited ability of the radiation to counteract the black hole gravitational attraction, we expect to find lower typical velocities with respect to the non-relativistic scenario.

Methods.We integrated the relativistic-corrected outflow equation of motion for a realistic set of starting conditions. We concentrated on a range of ionisations, column densities, and launching radii consistent with those typically estimated for UFOs. We explore a one-dimensional, spherical geometry and a three-dimensional setting with a rotating, thin accretion disc.

Results.We find that the inclusion of special relativity effects leads to sizeable differences in the wind dynamics and thatvis reduced up to 50% with respect to the non-relativistic treatment. We compare our results with a sample of UFOs from the literature and we find that the relativistic-corrected velocities are systematically lower than the reported ones, indicating the need for an additional mechanism, such as magnetic driving, to explain the highest velocity components. Finally, we note that these conclusions, derived for AGN winds, are generally applicable.
About the features of the time course of the average annual air temperature in the territory of the Debed river basin (Armenia)
Authors: Margaryan Varduhi , Tsibulskii Gennady , Raevich Ksenia
Published: December 2020

The article examines the features of the time course of the average annual air temperature in the Debed river basin in Armenia. As a starting material, we used daily data of actual observations of the temperature of the surface air layer for a year in the Debed river basin. The study was carried out at 6 meteorological stations in the Debed river basin based on long-term observation data series from 1930 to the present (2018). Analysis of the trend lines of temporal changes in air temperatures shows that at all meteorological stations currently operating on the territory of the basin, there is mainly a tendency for an increase in temperatures of annual values.
PI-RADS 2.1 – Image Interpretation: The Most Important Updates and Their Clinical Implications
Authors: Beyer Thomas , Schlemmer Heinz-Peter , Weber Marc-André , Thierfelder Kolja M.
Published: December 2020

Background Multiparametric magnetic resonance imaging (MRI) of the prostate plays a central role in the diagnosis of patients with suspected prostate cancer. The increasing distribution and application of the guideline for the standardization of image acquisition, evaluation, and reporting (Prostate Imaging – Reporting and Data System, PI-RADS), which was updated in 2019 to version 2.1, contributes to the success of the technique.

Materials and Methods The most important updates of PI-RADS version 2.1 presented in 2019 compared to the previous version PI-RADS 2.0 are highlighted and interpreted with regard to their clinical implications.

Results PI-RADS version 2.1 aims to simplify the application of the scoring scheme without changing the basic concept of dominant sequences (DWI in the peripheral zone, T2 in the transition zone). Of particular importance are the increasing role of diffusion-weighted imaging in the transition zone, the now mandatory high b-value of at least 1400 s/mm2, and new information on the assessment of the central zone and the anterior fibromuscular stroma.

Conclusion PI-RADS version 2.1 published in 2019 addresses a number of changes to the previous version, including both the examination technique and image interpretation. Prospective clinical studies have yet to prove the extent to which the goals of reducing interreader variability and increasing the detection rate in the transition zone will be achieved.

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Citation Format
Ultradiscrete bifurcations for one dimensional dynamical systems
Authors: Ohmori Shousuke , Yamazaki Yoshihiro
Published: December 2020

Bifurcations of one dimensional dynamical systems are discussed based on some ultradiscrete equations. The ultradiscrete equations are derived from normal forms of one-dimensional nonlinear differential equations, each of which has saddle-node, transcritical, or supercritical pitchfork bifurcations. An additional bifurcation, which is similar to the flip bifurcation, is found in ultradiscrete equations for supercritical pitchfork bifurcations. Dynamical properties of these ultradiscrete bifurcations can be characterized with graphical analysis. As an example of application of our treatment, we focus on an ultradiscrete equation of the FitzHugh–Nagumo model and discuss its dynamical properties.
Target normal sheath acceleration with a large laser focal diameter
Authors: Park J. , Bin J. H. , Steinke S. , Ji Q. , Bulanov S. S. , Thévenet M. , Vay J.-L. , Schenkel T. , Geddes C. G. R. , Schroeder C. B. , Esarey E.
Published: December 2020

The dependence of the laser-driven ion acceleration from thin titanium foils in the Target Normal Sheath Acceleration (TNSA) regime on target and laser parameters is explored using two dimensional particle-in-cell simulations. The oblique incidence (θL=45°) and large focal spot size (w0=40μm) are chosen to take an advantage of quasi one-dimensional geometry of sheath fields and effective electron heating. This interaction setup also reveals low and achromatic angular divergence of a proton beam. It is shown that the hot electron temperature deviates from the ponderomotive scaling for short laser pulses and small pre-plasmas. This deviation is mainly due to the laser sweeping, as the short duration laser pulse each moment in time effectively heats only a fraction of a focal spot on the foil. This instantaneous partial heating results in an electron temperature deviation from the ponderomotive scaling and, thus, lower maximum proton energies than it could have been expected from the TNSA theory.
Vertical conductivity and Poole–Frenkel-ionization of Mg acceptors in AlGaN short-period superlattices with high Al mole fraction
Authors: Muhin A. , Guttmann M. , Kuhn C. , Mickein E. , Aparici J. R. , Ziffer E. , Susilo N. , Sulmoni L. , Wernicke T. , Kneissl M.
Published: December 2020

Mg-doped AlGaN short-period superlattices with a high aluminum mole fraction are promising to fabricate highly efficient deep UV light emitting diodes. We present a robust and easy-to-implement experimental method for quantification of the vertical component of the anisotropic short-period superlattice conductivity based on current–voltage characteristics of devices with varying short-period superlattice thicknesses. In particular, the vertical conductivity of Al0.71Ga0.29N/Al0.65Ga0.35N:Mg short-period superlattices is investigated and found to be strongly affected by the temperature and by the applied electric field. At room temperature, the vertical conductivity varies between 5.5 × 10−7 Ω −1 cm−1 at 0.05 MV cm−1 and 6.7 × 10−5 Ω−1 cm−1 at 0.98 MV cm−1 and increases by almost two orders of magnitude when the temperature increases up to 100 °C. This behavior is in very good agreement with simulations based on a 3D-Poole–Frenkel model. In addition, the zero-field ionization energy and the inter-trap distance of the Mg acceptors in the AlGaN short-period superlattices were determined to be 510 ± 20 meV and 5.1 ± 0.3 nm, respectively.
Revealing a multiplex brain network through the analysis of recurrences
Authors: Frolov Nikita , Maksimenko Vladimir , Hramov Alexander
Published: December 2020

A multilayer approach has recently received particular attention in network neuroscience as a suitable model to describe brain dynamics by adjusting its activity in different frequency bands, time scales, modalities, or ages to different layers of a multiplex graph. In this paper, we demonstrate an approach to a frequency-based multilayer functional network constructed from nonstationary multivariate data by analyzing recurrences in application to electroencephalography. Using the recurrence-based index of synchronization, we construct intralayer (within-frequency) and interlayer (cross-frequency) graph edges to model the evolution of a whole-head functional connectivity network during a prolonged stimuli classification task. We demonstrate that the graph edges’ weights increase during the experiment and negatively correlate with the response time. We also show that while high-frequency activity evolves toward synchronization of remote local areas, low-frequency connectivity tends to establish large-scale coupling between them.