bluuebunny/crossref_metadata_2025 huggingface dataset:
Photo-switchable electron-transporting layers for self-driven perovskite photodetectors towards high detectivity
Authors: Zhang Qinglei , Shou Meihua , Xu Yucheng , Zheng Jiaxin , Wen Xinbo , Zhao Yang , Wang Huan , Liu Linlin , Xie Zengqi
Published: October 2020

Organic dye molecules doped ZnO, a kind of photoconductive hybrid material, is used as electron-transporting layer to effectively increase the detectivity in perovskite photodetectors by reducing the dark current without sacrificing photocurrent.
Highly luminescent aggregate-induced emission from polyethylene glycol-coated carbon quantum dot clusters under blue light illumination
Authors: Juang Ruey-Shin , Fu Chun-Chieh , Hsieh Chien-Te , Gu Siyong , Ashraf Gandomi Yasser , Liu Shou-Hsuan
Published: October 2020

Carbon quantum dots (CQDs) have been considered as one of the most promising fluorescent nanomaterials.
Gallium nitride formation in liquid metal sonication
Authors: Cai Shengxiang , Mayyas Mohannad , Saborio Maricruz G. , Ghasemian Mohammad B. , Tang Jianbo , Daeneke Torben , Han Jialuo , Esmailpour Ali Asghar , Allioux Francois-Marie , Kalantar-Zadeh Kourosh
Published: October 2020

This work presents the room temperature nitridation of gallium-based liquid metal alloy particles during sonication.
Molecular bending as a vital step toward transforming planar PAHs to fullerenes and tubular structures
Authors: Chen Tao , Wang Yang
Published: October 2020

Context. Polycyclic aromatic hydrocarbons (PAHs) and fullerenes are the largest molecules found in the interstellar medium (ISM). They are abundant and widespread in various astronomical environments. However, the detailed connection between these two species is unknown; in particular, no quantum chemical studies have been performed.

Aims. In this work, we investigate a vital step in transforming planar PAHs to fullerenes, that is, the tubulation processes of PAHs.

Methods. We used density functional theory for this study. The molecular structures and vibrational frequencies were calculated using the hybrid density functional B3LYP method. To better describe intermolecular forces, we considered Grimme’s dispersion correction in the calculations for this work. Intrinsic reaction coordinate calculations were also performed to confirm that the transition state structures are connected to their corresponding local potential energy surface minima.

Results. As expected, we find that it is easier to bend a molecule as it gets longer, whereas it is harder to bend the molecule if it gets “wider” (i.e., with more rows of benzene rings). The change of multiplicity slightly alters the bending energies, while (a complete) dehydrogenation alleviates the bending barrier significantly and facilitates the formation of pentagons, which may act as an indispensable step in the formation of fullerenes in the ISM.
Synthèse bibliographique : étude des propriétés physico-chimiques du phosphogypse Marocain
Authors: Ennaciri Yassine , Bettach Mohammed , Cherrat Ayoub , Zdah Ilham , El Alaoui-Belghiti Hanan
Published: October 2020

La production de l’acide phosphorique au monde engendre l’accumulation d’une grande quantité d’un sous-produit acide appelé phosphogypse (PG). La grande partie de ce PG est rejetée sans aucun traitement dans l’environnement, ce qui forme une source significative de contamination à longue durée. Le PG Marocain est principalement formé par le sulfate de calcium, à côté de diverses impuretés telles que les phosphates, les fluorures, les matières organiques, les métaux lourds et les éléments radioactifs. Cet article détaille en particulier les différentes propriétés physico-chimiques du PG Marocain. La compréhension de ces propriétés permet en générale d’identifier les différents agents de contamination de l’environnement contenus dans ce résidu. De plus, les facteurs affectant la présence des différentes sortes d’impuretés dans le PG sont aussi discutés.
Influence of physicochemical properties of the soil solution on the 226Ra distribution coefficient in soils
Authors: Blanco Rodríguez P. , Vera Tomé F. , Lozano J.C.
Published: October 2020

Defined as the ratio between the isotope’s activity concentrations in the solid fraction of the soil and in the soil solution, the distribution coefficient (Kd) of 226Ra is an equilibrium constant that encompasses all the interface processes that comprise its sorption as a whole. However, there is a great variability in the reported measured values of radium Kd. A first classification of soils in terms of their texture reduces this variability somewhat, but the chemical environment of the soil solution is also expected to exert a significant influence on the sorption process and therefore on the Kd. In the present work, linear regressions are applied to look for relationships between the radium Kd and the physicochemical properties of the soil solution. The soil solutions were studied of three soils with different textural characteristics but taken from the same natural soil. For the soil classified as loamy coarse sand, the significant independent variables affecting Kd were the pH, conductivity, and dissolved organic matter; for the soil classified as loamy fine sand, they were the bivalent cation concentration and pH; and for the soil classified as loam, they were the conductivity and nitrate concentration.
Knorpel-Knochenmark-Mikro-Konnektoren im subchondralen Knochen
Authors: Taheri Shahed , Böker Kai O. , Lehmann Wolfgang , Schilling Arndt Friedrich
Published: October 2020

Die Interaktion des subchondralen Knochens mit dem Gelenkknorpel ist von grundlegender Bedeutung für die Gelenkphysiologie. Studien an Tier- und Humanmodellen haben gezeigt, dass der untere Rand des Gelenkknorpels über kleine Defekte oder Mikrokanäle mit der Markhöhle verbunden ist. Obwohl diese Knorpel-Knochenmark-Mikro-Konnektoren (KKMK
) möglicherweise für den molekularen Austausch, den Knochen-Knorpel-Crosstalk und sogar die Knorpelernährung von entscheidender Bedeutung sein können, ist das derzeitige Wissen über sie begrenzt und inkohärent. Diese Übersicht fasst die bisher beschriebenen Merkmale dieser anatomischen Mikroarchitektur bei verschiedenen Spezies zusammen, untersucht wiederkehrende Muster in der Literatur und erörtert ihre potenzielle Funktionalität.
Maternal Hypothyroidism Increases the Risk of Attention-Deficit Hyperactivity Disorder in the Offspring
Authors: Peltier Morgan R. , Fassett Michael J. , Chiu Vicki Y. , Getahun Darios
Published: October 2020

Objective This study aimed to determine if hypothyroidism prior to, or during, pregnancy increases the risk of attention-deficit hyperactivity disorder (ADHD) in the child and how the association may be modified by preterm birth, sex of the child, and race-ethnicity.

Study Design Data were abstracted from linked maternal–child medical records. Incidence rate differences (IRDs), adjusted hazard ratios (aHRs), and their 95% confidence intervals (CIs) were estimated to evaluate the association of maternal hypothyroidism with childhood ADHD risk. Stratified analyses were used to evaluate whether the association is affected by timing of first diagnosis, gestational age at birth (term vs. preterm), sex, and race-ethnicity.

Results Hypothyroidism diagnosed prior to (IRD = 1.30), or during (IRD = 0.59) pregnancy increases the risk of ADHD in the children (aHR = 1.27; 95% CI: 1.15, 1.41, and 1.17; 95% CI: 1.00, 1.38). The association was strongest when diagnosed during the first trimester (IRD = 0.97 and aHR = 1.28; 95% CI: 1.04, 1.58). For children born preterm, there was significantly increased risk of ADHD if their mothers were diagnosed prior to (IRD = 3.06 and aHR = 1.43; 95% CI: 1.09, 1.88), but not during pregnancy. The effect of maternal hypothyroidism on increased risk of ADHD was stronger for boys (IRD = 1.84 and aHR = 1.26; 95% CI: 1.14, 1.40) than it was for girls (IRD = 0.48 and aHR = 1.19; 95% CI: 1.01, 1.40) and for Hispanic children (IRD = 1.60 and aHR = 1.45; 95% CI: 1.25, 1.68) compared with other race ethnicities.

Conclusion Exposure to maternal hypothyroidism during the periconceptual period significantly increases the risk of ADHD and that the association varies with gestational age at delivery, child sex, and race-ethnicity.

Key Points
Effect of the policy and consumption delay on the amplitude and length of business cycle
Authors: Lin Zi-Fei , Li Jiao-Rui , Wu Juan , Pham Viet-Thanh , Kapitaniak Tomasz
Published: October 2020

In this paper, the amplitude and the length of the business cycle are investigated. It is the first time the length of the business cycle based on the Goodwin model (one classical business cycle model) is discussed. The effect of the time delay of the economic policy and consumption on the amplitude and the length of the business cycle is studied. Meanwhile, the memory property of making economic policy is also considered. The theoretical amplitude of the business cycle is obtained by multiple-scale methods. The transitions of the amplitude induced by memory property and time delay are analyzed. How the economic parameter and random excitation affect the length of the business cycle is proposed. Based on the results, we can find that the time delay of both economic policy and consumption can induce the transitions. Moreover, the memory property of economic policy will change the critical value of the parameters when the transitions occur. In one typical induced investment function, the length of the business cycle is determined only by the autonomous investment and consumption. However, the length of the business cycle is not mainly affected by the autonomous investment and consumption in some other typical induced investment function. This states that the type of induced investment function has a very important role in determining the length of the business cycle.
Nonlocal operators are chaotic
Authors: Lizama Carlos , Murillo-Arcila Marina , Peris Alfred
Published: October 2020

We characterize for the first time the chaotic behavior of nonlocal operators that come from a broad class of time-stepping schemes of approximation for fractional differential operators. For that purpose, we use criteria for chaos of Toeplitz operators in Lebesgue spaces of sequences. Surprisingly, this characterization is proved to be—in some cases—dependent of the fractional order of the operator and the step size of the scheme.
Understanding the breakdown asymmetry of 4H-SiC power diodes with extended defects at locations along step-flow direction
Authors: Long Hu , Ren Na , Guo Qing , Gan Xinhui , Chen Lei , Zhang Weimin , Zhu Jiacong , Wei Feng , Sheng Kuang
Published: October 2020

Power electronic devices for high-voltage applications prefer wide-bandgap semiconductors such as silicon carbide, whereas the immaturity of epitaxial growth technology introduces many extended defects, some of which are crucial to the electrical performance of fabricated devices. Therefore, it is much expected to find out some deep relation between extended defects and device performance. In this work, based on comparisons of breakdown behaviors of 4H-SiC power diodes with or without extended defects of different types, the importance of several features of the extended defect, including the distance, length, and orientation, is reported. Besides, based on the experimental results from dark-field microscopy, near-ultra-violet photoluminescence and topography, and theoretical analysis with numerical calculations, the mechanism of a particular asymmetric breakdown behavior in 4H-SiC devices along the step-flow direction is revealed, which originates from the prevalent step-controlled epitaxy technology for the commercial 4H-SiC epitaxial wafer. With the proposed result and understanding, it is possible to achieve a higher yield in production at a similar material cost.
Influence of lunisolar tides on plants. Parametric resonance induced by periodic variations of gravity
Authors: Gouin Henri
Published: October 2020

Recent experiments conducted in the International Space Station highlight the apparent periodicity of leaf oscillations and other biological phenomena associated with rhythmic variations of lunisolar forces. These events are similar to those occurring on Earth but with greater effects over a shorter period of time. Among the possible disturbances, other than forced or self-existing oscillations, parametric resonances appear caused by a small periodic term; such is the case of fluids subjected to small periodic variations in gravitational forces in microscopic or mesoscopic plant channels filled with sap and air-vapor. The interface instabilities verify Mathieu’s second order differential equation resulting from a Rayleigh–Taylor stability model. These instabilities appear during the Moon’s rotation around the Earth and during the revolution of the International Space Station. They create impulses of pressure and sap movements in the network of roots, stems, and leaves. The model can explain the effects of the lunar tide on plant growth. The eccentricity of the lunar orbit around the Earth creates an important difference between the apogee and perigee of the Moon’s trajectory, and therefore, the tidal effects can depend on the distance between the Moon and the Earth.
Low intermittent flow promotes rat mesenchymal stem cell differentiation in logarithmic fluid shear device
Authors: Dash Sanat Kumar , Sharma Vineeta , Verma Rama Shankar , Das Sarit K.
Published: October 2020

Bone marrow mesenchymal stem cells are an ideal candidate for bone tissue engineering due to their osteogenic potential. Along with chemical, mechanical signals such as fluid shear stress have been found to influence their differentiation characteristics. But the range of fluid shear experienced in vivo is too wide and difficult to generate in a single device. We have designed a microfluidic device that could generate four orders of shear stresses on adherent cells. This was achieved using a unique hydraulic resistance combination and linear optimization to the lesser total length of the circuit, making the device compact and yet generating four logarithmically increasing shear stresses. Numerical simulation depicts that, at an inlet velocity of 160 μl/min, our device generated shear stresses from 1.03 Pa to 1.09 mPa. In this condition, we successfully cultured primary rat bone marrow mesenchymal stem cells (rBMSCs) in the device for a prolonged period of time in the incubator environment (four days). Higher cell proliferation rate was observed in the intermittent flow at 1.09 mPa. At 10 mPa, both upregulation of osteogenic genes and higher alkaline phosphatase activity were observed. These results suggest that the intermittent shear of the order of 10 mPa can competently enhance osteogenic differentiation of rBMSCs compared to static culture.
Stochastic effects on the dynamics of an epidemic due to population subdivision
Authors: Bittihn Philip , Golestanian Ramin
Published: October 2020

Using a stochastic susceptible–infected–removed meta-population model of disease transmission, we present analytical calculations and numerical simulations dissecting the interplay between stochasticity and the division of a population into mutually independent sub-populations. We show that subdivision activates two stochastic effects—extinction and desynchronization—diminishing the overall impact of the outbreak even when the total population has already left the stochastic regime and the basic reproduction number is not altered by the subdivision. Both effects are quantitatively captured by our theoretical estimates, allowing us to determine their individual contributions to the observed reduction of the peak of the epidemic.
Demonstration of nitrogen-incorporated ultrananocrystalline diamond photocathodes in a RF gun environment
Authors: Chen Gongxiaohui , Spentzouris Linda , Jing Chunguang , Conde Manoel , Ha Gwanghui , Liu Wanming , Power John , Wisniewski Eric , Sumant Anirudha V. , Antipov Sergey , Gomez Edgar , Kovi Kiran Kumar , Shao Jiahang
Published: October 2020

Quantum efficiency (QE), intrinsic emittance, and robustness are the three most important figures of merit for photocathodes, the first two determine the ultimate achievable brightness of an electron beam, and the third one directly correlates with the complications of a beamline design. Nitrogen-incorporated ultrananocrystalline diamond [(N)UNCD] materials are promising candidates for photocathode applications due to their remarkable electron emission performance as well as the moderate vacuum requirement. Two (N)UNCD photocathodes have been characterized in a realistic RF gun environment with the nicely balanced performance of all three figures of merit. The QE of the first (N)UNCD cathode (stored in air for two years before the test) was found to be 3.8 × 10−4 using a 262 nm UV laser and a cathode surface field of 30 MV/m. It was found that the QE of the second (N)UNCD sample (grown days before the test) was nearly the same and, therefore, demonstrates the exceptional environmental tolerance of the material. The intrinsic emittance of (N)UNCD was measured to be 1.00 μm/mm.
On the elastic rod models for mechanical tests of one-dimensional nanostructures under transverse loads
Authors: Wang Shijun , Xu Zhiping
Published: October 2020

Quantifying the intrinsic mechanical properties of one-dimensional nanostructures such as nanotubes and nanowires is technically challenging due to their extremely small sizes and large aspect ratios. In comparison with direct tensile measurements, displacement responses of an end-clamped rod under transverse loads are more significant and more feasible for experimental characterization. However, the displacement–force relationship could be non-trivial due to the presence of geometrical nonlinearity and contributions from both stretching and bending. Choosing a simple but reliable model to extract the mechanical parameters from experimental data is thus important for the design of tests. Starting from the fully nonlinear, extensible Kirchhoff rod theory, we explore the application scope of several simplifications by referring to recent experimental studies on carbon nanotubes. The horizontal displacement is shown to be crucial information for strain analysis in the stretching-dominated regime, and the constant-tension assumption fails at large loading amplitudes. The capability of several simplified models is assessed through the Euclidean distance between deflection curves, as well as the error in estimating the strain distribution. Practical issues such as boundary slippage and dynamical effects are also discussed. This study offers a theoretical groundwork to understand the mechanical responses of one-dimensional nanostructures in typical experimental setups and provides a standard or guideline for the experimental design.
What history teaches us about vaccines and pandemics
Authors: Isaacs David
Published: October 2020

The history of immunisation is full of heroes but also full of villains, and our successes are tempered by tragedies. Despite the urgent need for a vaccine against SARS-CoV-2, we should not neglect the lessons of history. These include ethical issues relating to vaccine safety, such as the possible risks of vaccine-induced enhancement witnessed with dengue vaccine in the Philippines, and how our decisions may be represented by the anti-vaxx movement.
Echolocating bats detect but misperceive a multidimensional incongruent acoustic stimulus
Authors: Danilovich Sasha , Shalev Gal , Boonman Arjan , Goldshtein Aya , Yovel Yossi
Published: October 2020

Significance

How do we build a perception from incoming sensory information? To accurately perceive the environment, the brain has to integrate information across different sensory modalities and to analyze multiple sensory dimensions within a sensory modality. We studied this integration in echolocating bats, the masters of active acoustic sensing. By presenting them with targets whose acoustic dimensions were incoherent, we managed to induce misperception, which caused the bats to repeatedly try to fly through a wall even though they detected it with their echolocation. We demonstrate that certain relations between the dimensions must hold to allow accurate perception. Nevertheless, adult bats can learn new relations rapidly. Notably, no misperception was observed in pups, confirming that these relations are not innate.
The role of Ca
2+
and protein scaffolding in the formation of nature’s water oxidizing complex
Authors: Avramov Anton P. , Hwang Hong J. , Burnap Robert L.
Published: October 2020

Significance

Unlike cofactor insertion into other metalloproteins, assembly of the photosynthetic water oxidation complex of photosystem II (PSII) in plants, algae, and cyanobacteria is a light-driven process that photooxidatively incorporates Mn
2+
and Ca
2+
ions into the protein matrix forming the catalytic Mn
4
CaO
5
metal cluster. This self-assembly process is important both for de novo biogenesis and for the frequent repair of PSII due to its susceptibility to photodamage. While the basic kinetic scheme for this process was established nearly 50 y ago, the molecular details have remained enigmatic. Here we describe results on the role of inorganic and protein cofactors and integrate them with previous information to obtain an important upgrade in our understanding of this process.
Fine-scale spatial clustering of measles nonvaccination that increases outbreak potential is obscured by aggregated reporting data
Authors: Masters Nina B. , Eisenberg Marisa C. , Delamater Paul L. , Kay Matthew , Boulton Matthew L. , Zelner Jon
Published: October 2020

Significance

The United States witnessed large, persistent measles outbreaks in 2019, nearly losing its elimination status, despite achieving national measles vaccination coverage above the World Health Organization recommendation of 95%. Previous research showed that measles outbreaks in high-coverage contexts are driven by spatially clustered nonvaccination, locally depressing immunity levels. We perform a series of computational experiments to assess the impact of clustering of nonvaccination on outbreak potential and how disease risk predictions might be biased by measuring vaccination rates at coarse spatial scales. When nonvaccination is locally clustered, reporting aggregated data can result in substantial underestimates of outbreak risk. This research illustrates that finer-scale vaccination data should be collected to prevent a return to endemic measles transmission in the United States.
Evolution of regulatory signatures in primate cortical neurons at cell-type resolution
Authors: Kozlenkov Alexey , Vermunt Marit W. , Apontes Pasha , Li Junhao , Hao Ke , Sherwood Chet C. , Hof Patrick R. , Ely John J. , Wegner Michael , Mukamel Eran A. , Creyghton Menno P. , Koonin Eugene V. , Dracheva Stella
Published: October 2020

Significance

The cerebral cortex of the human brain is a highly complex, heterogeneous tissue that contains many cell types that are exquisitely regulated at the level of gene expression by noncoding regulatory elements, presumably in a cell-type–dependent manner. However, assessing the regulatory elements in individual cell types is technically challenging, and therefore most of the previous studies on gene regulation were performed with bulk brain tissue. Here we analyze two major types of neurons isolated from the cerebral cortex of humans, chimpanzees, and rhesus macaques, and report complex patterns of cell-type–specific evolution of the regulatory elements in numerous genes. Many genes with evolving regulation are implicated in language abilities as well as psychiatric disorders.
The critical role of cloud–infrared radiation feedback in tropical cyclone development
Authors: Ruppert James H. , Wing Allison A. , Tang Xiaodong , Duran Erika L.
Published: October 2020

Significance

The deep clouds that make up tropical disturbances, the precursors to more intense tropical cyclones (TCs) (including hurricanes and typhoons), effectively trap infrared radiation emitted by Earth’s surface and lower atmosphere. Our results demonstrate that the local atmospheric warming caused by this “cloud greenhouse effect” is a key trigger for promoting and accelerating the evolution of such precursor storms into intense TCs. The forecasting of TC formation remains extremely challenging, while the representation of cloud processes and their feedback with radiation is a large source of uncertainty in the numerical models that forecasts rely upon. Our results suggest that focusing future research on constraining these processes in models holds promise for key progress in the prediction of these devastating storms.
Reconfigurable multifunctional ferrofluid droplet robots
Authors: Fan Xinjian , Dong Xiaoguang , Karacakol Alp C. , Xie Hui , Sitti Metin
Published: October 2020

Significance

This work proposes reconfigurable multifunctional ferrofluid droplets as soft robots to overcome the limitation of existing magnetically actuated miniature soft robots based on elastomers, i.e., they cannot navigate inside very clustered and constrained spaces and reconfigure their shapes in situ for diverse tasks, due to limited deformability and predesigned shapes. We propose a fundamental mechanism of controlling reconfigurable large deformation (e.g., splitting) and coordinated motions of multiple ferrofluid droplets by programming external magnetic fields spatiotemporally. We employ this mechanism to achieve multiple functionalities, including on-demand liquid-cargo delivery, morphing for efficient and versatile manipulation of delicate objects, and programmable fluidic-mixing function, potentially enabling unprecedented functionalities in lab/organ-on-a-chip, fluidics, bioengineering, and medical device applications, beyond magnetically actuated elastomer-based soft robots.
Identification of a degradation signal at the carboxy terminus of SREBP2: A new role for this domain in cholesterol homeostasis
Authors: Kober Daniel L. , Xu Shimeng , Li Shili , Bajaj Bilkish , Liang Guosheng , Rosenbaum Daniel M. , Radhakrishnan Arun
Published: October 2020

Significance

Sterol regulatory element-binding proteins (SREBPs) are transcription factors that control production of cholesterol and other lipids. In endoplasmic reticulum (ER) membranes, SREBPs form complexes with Scap, a cholesterol-sensing membrane protein. When cholesterol levels are low, Scap escorts SREBPs from the ER to the Golgi where proteolytic cleavage releases the transcription factor domain that turns on genes involved in cholesterol synthesis. The remainder of SREBP still bound to Scap must be eliminated so that Scap can be recycled to bind additional SREBPs. Here, we discover a degradation signal in SREBP that mediates clearance of the cleaved SREBP fragments from Scap. Such clearance is essential for the recycling of Scap and thus it is a central step in regulation of cholesterol homeostasis.
Bilingualism and interculture: what are teachers doing? (Bilingüismo e intercultura: ¿qué están haciendo los docentes?)
Authors: Pérez-Gracia Elisa , Serrano-Rodríguez Rocío , Carpio Antonio J.
Published: October 2020

One of the main aims of Content and Language Integrated Learning (CLIL) is to develop intercultural awareness and understanding among students. The objective of this study is to analyse whether CLIL primary education teachers implement the intercultural axis of CLIL in the strategies and resources they plan and use in their daily lessons, and which factors may influence this. An open-question questionnaire was used to carry out an in-depth analysis of the opinions of 59 CLIL primary education teachers working at schools in Córdoba (Spain). The results show that communicative and cooperative activities, along with those activities in which interaction is the focus, are those most frequently employed by CLIL teachers to enhance the intercultural axis. Information and Communication Technology (ICT) resources are those most frequently applied in order to promote intercultural awareness. Independent variables such as gender, subject taught, years of experience and the textbook used had a significant influence on how teachers plan and put their strategies and didactic resources into practice. The outcomes indicate the need to reinforce CLIL teacher training in this regard.
Effect of marathon characteristics and runners’ time category on pacing profile
Authors: Oficial‐Casado Fran , Uriel Jordi , Pérez‐Soriano Pedro , Priego Quesada Jose Ignacio
Published: October 2020

This study aimed to analyse differences in pacing profiles in four marathon competitions and to explore that pacing per time category. A database of 91,493 runners gathered from 4 different races was analysed (Valencia, Chicago, London and Tokyo Marathon). Participants were categorized in accordance with their completion time. The relative speed of each section for each runner was calculated as a percentage of the average speed for the entire race. In the four marathons studied, the first 5 km differed widely, presenting London the highest relative speeds (5 km: CI95% London vs. Valencia [12.1, 13.6%], p < 0.001 and ES = 2.1; London vs. Chicago [5.5, 7.1%], p < 0.001 and ES = 1.1; London vs. Tokyo [15.2, 16.8%], p < 0.001 and ES = 2.3). Races did not differ at each section for high‐performance runners (sub‐2:30), but differences between races increased as the time category increases (e.g. 35 km and sub‐3:00: CI95% London vs. Tokyo [−3.1, −1.8%], p < 0.001 and ES = 0.7; 35 km and sub‐5:00: London vs. Tokyo [−9.8, −9.2%], p < 0.001 and ES = 1.3). The difference in relative speed between the first and second half of the marathon was higher in London than in the other marathons (e.g. CI95% London vs. Valencia [10.3, 10.8%], p < 0.001 and ES = 1.3). In conclusion, although race characteristics affect pacing, this effect was higher as the category time increases. Race pacing characteristics should be taken into consideration for runners and coaches choosing the race and working on pacing strategies, for researches to extrapolate or interpret results, or for race organizations to improve its pacing characteristics.
Large scale anomalies in the CMB and non-Gaussianity in bouncing cosmologies
Authors: Agullo Ivan , Kranas Dimitrios , Sreenath V
Published: October 2020

We propose that several of the anomalies that have been observed at large angular scales in the CMB have a common origin in a cosmic bounce that took place before the inflationary era. The bounce introduces a new physical scale in the problem, which breaks the almost scale invariance of inflation. As a result, the state of scalar perturbations at the onset of inflation is no longer the Bunch–Davies vacuum, but it rather contains excitations and non-Gaussianity, which are larger for infrared modes. We argue that the combined effect of these excitations and the correlations between CMB modes and longer wavelength perturbations, can account for the observed power suppression, for the dipolar asymmetry, and it can also produce a preference for odd-parity correlations. The model can also alleviate the tension in the lensing amplitude A
L. We adopt a phenomenological viewpoint by considering a family of bounces characterized by a couple of parameters. We identify the minimum set of ingredients needed for our ideas to hold, and point out examples of theories in the literature where these conditions are met.
Constraint algebra in tetrad bigravity
Authors: Soloviev V O
Published: October 2020

The constraint algebra is derived in the second order tetrad Hamiltonian formalism of the bigravity. This is done by a straightforward calculation without involving any insights, implicit functions, and Dirac brackets. The tetrad approach is the only way to present the bigravity action as a linear functional of lapses and shifts and the Hassan–Rosen transform (characterized as ‘a complicated redefinition of the shift variable’ according to the authors) appears here not as an ansatz but as fixing of a Lagrange multiplier. A comparison of this approach with the other ones is provided.
Is gravity the weakest force?
Authors: Shirai Satoshi , Yamazaki Masahito
Published: October 2020

It has recently been suggested that ‘gravity is the weakest force’ in any theory with a suitable UV completion within quantum gravity. One formulation of this statement is the scalar weak gravity conjecture (WGC), which states that gravity is weaker than the force originating from scalar fields. We study the scalar WGC in de Sitter (dS) space, and discuss its low-energy consequences in light of the experimental searches for fifth forces and violations of the equivalence principle. We point out that some versions of the scalar WGC forbid the existence of very light scalar particles, such as the quintessence and axion-like particles. The absence of the quintessence field means that these versions of the scalar WGC are in phenomenological tension with the recently-proposed dS swampland conjecture and its refinements. Some other versions of the scalar WGC escape these constraints, and could have interesting phenomenological consequences.
Randomly evolving Platonic Solids: a zero-player game
Authors: Platini T , Low R
Published: October 2020

We investigate a simple a discrete time random process based on the construction of Platonic solids. As is surprisingly often the case with apparently simple processes, we find some intriguing results, in this case requiring a careful consideration of how the probability distributions describing this process behave. The investigation proceeds by a fruitful combination of geometry, probability and elementary real analysis. We conclude with a consideration of the limiting behaviour of the probability distributions describing the size of the solid as the number of steps grows.
On iteratively regularized predictor–corrector algorithm for parameter identification
*
Authors: Smirnova Alexandra , Bakushinsky Anatoly
Published: October 2020

We study a constrained optimization problem of stable parameter estimation given some noisy (and possibly incomplete) measurements of the state observation operator. In order to find a solution to this problem, we introduce a hybrid regularized predictor–corrector scheme that builds upon both, all-at-once formulation, recently developed by B. Kaltenbacher and her co-authors, and the so-called traditional route, pioneered by A. Bakushinsky. Similar to all-at-once approach, our proposed algorithm does not require solving the constraint equation numerically at every step of the iterative process. At the same time, the predictor–corrector framework of the new method avoids the difficulty of dealing with large solution spaces resulting from all-at-once make-up, which inevitably leads to oversized Jacobian and Hessian approximations. Therefore our predictor–corrector algorithm (PCA) has the potential to save time and storage, which is critical when multiple runs of the iterative scheme are carried out for uncertainty quantification. To assess numerical efficiency of novel PCA, two parameter estimation inverse problems in epidemiology are considered. All experiments are carried out with real data on COVID-19 pandemic in Netherlands and Spain.
A new boson approach for the wobbling motion in even–odd nuclei
Authors: Raduta A A , Raduta C M , Poenaru R
Published: October 2020

A triaxial core rotating around the middle axis, i.e. two-axis, is cranked around the one-axis, due to the coupling of an odd proton from a high j orbital. Using the Bargmann representation of a new and complex boson expansion of the angular momentum components, the eigenvalue equation of the model Hamiltonian acquires a Schrödinger form with a fully separated kinetic energy. From a critical angular momentum, the potential energy term exhibits three minima, two of them being degenerate. Spectra of the deepest wells reflects a chiral-like structure. Energies corresponding to the deepest and local minima respectively, are analytically expressed within a harmonic approximation. Based on a classical analysis, a phase diagram is constructed. It is also shown that the transverse wobbling mode is unstable. The wobbling frequencies corresponding to the deepest minimum are used to quantitatively describe the wobbling properties in 135Pr. Both energies and e.m. transition probabilities are described.
Gap opening in graphene nanoribbons by application of simple shear strain and in-plane electric field
Authors: Bandeira N S , da Costa D R , Chaves A , Farias G A , Filho R N Costa
Published: October 2020

The effects of shear strain and applied in plane electric field on the electronic properties of monolayer graphene nanoribbons (GNRs) are theoretically investigated. Band structures and the probability densities are calculated within the tight-binding model and the mechanical stresses submitted to the GNRs are taken into account by using the theory of linear elasticity with joint modifications in the elongation of the nearest-neighbor vectors and the modification of the hopping parameters. The energy gaps for specific widths of (semiconducting) armchair nanoribbons are verified also in the presence of either strain or field, whereas zigzag nanoribbons are metallic for any value of strain and exhibit a small gap for any value of field. However, our results demonstrate that when both strain and electric field are combined, a significant energy gap is always observed in the band structure, for any width or edge type of the ribbon. Moreover, the obtained total wave function is asymmetric along the ribbon width due to the applied electric field that pushes the electrons to one side of the ribbon and, under shear strain, a peak at the center of the ribbon in the spatial distribution is also observed owing to the preferable localization around the almost undeformed carbon bonds at ribbon center.
A new Wi-Fi dynamic selection of nearest neighbor localization algorithm based on RSS characteristic value extraction by hybrid filtering
Authors: Peng Xuesheng , Chen Ruizhi , Yu Kegen , Guo Guangyi , Ye Feng , Xue Weixing
Published: October 2020

Fingerprinting localization based on Wi-Fi received signal strength (RSS) is the most widely used indoor localization method. It typically includes offline training and online matching phases. The selection of the RSS characteristic value is a key step. The weighted K nearest neighbor (WKNN) algorithm is the most commonly used position-determination algorithm. The mean value of the RSS data collected over a time interval is usually taken as its characteristic value. However, the RSS measurements contain Gaussian and non-Gaussian noise, which cannot be filtered out effectively by the mean value method. The traditional WKNN algorithm adopts a fixed

K

. However, reference points far away from the test point (TP) may be selected as the nearest neighbors to participate in the position calculation, which may result in accuracy degradation. This paper proposes the weighted dynamic K nearest neighbor algorithm (WDKNN-HF), which utilizes a hybrid of particle filtering and Kalman filtering to extract the RSS characteristic value. In the online matching phase, a dynamic K matching algorithm based on Euclidean distances is developed to determine the coordinates of TPs. Two experiments are conducted in two different indoor scenes. Experimental results demonstrate that the proposed algorithm can obtain better positioning accuracy than existing algorithms, such as KNN, WKNN, enhanced-WKNN (EWKNN) and self-adaptive weighted K nearest neighbor (SAWKNN).
Atomic layer deposition of tungsten sulfide using a new metal-organic precursor and H2S: thin film catalyst for water splitting
Authors: Kim Deok-Hyun , Ramesh Rahul , Nandi Dip K , Bae Jong-Seong , Kim Soo-Hyun
Published: October 2020

Transition metal dichalcogenides (TMDs) are extensively researched in the past few years due to their two-dimensional layered structure similar to graphite. This group of materials offers tunable optoelectronic properties depending on the number of layers and therefore have a wide range of applications. Tungsten disulfide (WS2) is one of such TMDs that has been studied relatively less compared to MoS2. Herein, WS
x
thin films are grown on several types of substrates by atomic layer deposition (ALD) using a new metal-organic precursor [tris(hexyne) tungsten monocarbonyl, W(CO)(CH3CH2C≡CCH2CH3)3] and H2S molecules at a relatively low temperature of 300 °C. The typical self-limiting film growth by varying both, precursor and reactant, is obtained with a relatively high growth per cycle value of ∼0.13 nm. Perfect growth linearity with negligible incubation period is also evident in this ALD process. While the as-grown films are amorphous with considerable S-deficiency, they can be crystallized as h-WS2 film by post-annealing in the H2S atmosphere above 700 °C as observed from x-ray diffractometry analysis. Several other analyses like Raman and x-ray photoelectron spectroscopy, transmission electron microscopy, UV–vis. spectroscopy are performed to find out the physical, optical, and microstructural properties of as-grown and annealed films. The post-annealing in H2S helps to promote the S content in the film significantly as confirmed by the Rutherford backscattering spectrometry. Extremely thin (∼4.5 nm), as-grown WS
x
films with excellent conformality (∼100% step coverage) are achieved on the dual trench substrate (minimum width: 15 nm, aspect ratio: 6.3). Finally, the thin films of WS
x
(as-grown and 600/700 °C annealed) on W/Si and carbon cloth substrate are investigated for electrochemical hydrogen evolution reaction (HER). The as-grown WS
x
shows poor performance towards HER and is attributed to the S-deficiency, amorphous character, and oxygen contamination of the WS
x
film. Annealing the WS
x
film at 700 °C results in the formation of a crystalline layered WS2 phase, which significantly improves the HER performance of the electrode. The study reveals the importance of sulfur content and crystallinity on the HER performance of W-based sulfides.
Dual functional modes for nanostructured p-Cu2O/n-Si heterojunction photodiodes
Authors: Huang Chun-Ying , Wei En-Chun , Yuan Chia-Tse
Published: October 2020

Many applications require a photodetector (PD) with multiple functional modes. This study demonstrates a dual functional PD with a simple structure that uses a nanostructured p-Cu2O/n-Si heterojunction. This device features a self-powering characteristic for an open-circuit voltage (V
oc) of 0.5 V and exhibits an external quantum efficiency (EQE) of 3780% at a reverse bias of −5 V. There is a high EQE at low reverse-bias because trapped holes cause charge to be injected from the electrode. The nanostructured p-Cu2O/n-Si heterojunction also has a high response speed (<10 ms) in the self-powered mode because there is a built-in potential within p–n junction. This study shows that a nanostructured p-Cu2O/n-Si heterojunction acts as a self-powered PD for reducing power consumption and as a photomultiplication (PM)-type PD with high internal gain.
Inhomogeneity-mediated systematic reduction of the Schottky barrier in a Au/GaN nanorod film interface
Authors: Pant Rohit Kumar , Roul Basanta , Kumar Singh Deependra , Chowdhury Arun Malla , Nanda K K , Krupanidhi S B
Published: October 2020

Self-aligned GaN nanorods of various densities are grown on an r-plane Al2O3 substrate with Stranski–Krastanov or layer-plus-island growth conditions by using a plasma-assisted molecular beam epitaxy system. These conditions result in the formation of a GaN nanorod matrix on an epitaxial GaN thin film. The orientation of the nanorods was found to be at an inclination of ∼60° from the substrate. As expected, the GaN thin film grows along the [11–20] direction, but interestingly the nanorods have a preferential growth direction along the [0002] axis. The overall structure mimics the Gaussian distribution of Schottky barriers at the metal–semiconductor interface. The GaN nanorod/thin-film matrix systematically causes the well-known Au/GaN Schottky metal–semiconductor interface to display an Ohmic type of behavior. A systematic reduction of the Schottky barrier is observed with an increase in the GaN nanorod density (from 5 to 65 nanorods micron−2). The overall configuration provides a tunable Gaussian distribution of Schottky barriers with nanorod density, which could be extremely useful for replacing conventional multi-level electrode stacking techniques.
Effect of doping profile variation on nanoscale cylindrical gate carbon nanotube field-effect transistor: a computational study using nonequilibrium Green’s function formalism
Authors: Mahdi Muntasir , Hossain Md Anik , Hussain Sazzad , Hasan Mehedi , Zaman Hasan U , Saha Jibesh Kanti
Published: October 2020

The scaling down of modern devices beyond 15 nm has faced major setbacks as it engendered short channel effects which were seemingly inexorable. One of the solutions proposed was to replace the conventional silicon channel with carbon nanotubes (CNTs), giving rise to the carbon nanotube field-effect transistor (CNTFET). CNTs provide unrivaled electrical and mechanical properties which make them an attractive alternative to silicon for channel materials. In this research work, a cylindrical gate CNTFET model is proposed, and its performance is studied and compared with existing experimental results. The performance of the device due to the variation in the doping profile of the source and drain is studied to realize a device that can manifest superior characteristics compared with existing devices. A model with a non-uniform doping profile is proposed that results in a significant reduction in leakage current. The characteristics upon which the performance is evaluated are the on/off current ratio (I
ON/I
OFF), subthreshold swing (SS), and threshold voltage. By adjusting various parameters, a device is constructed with I
ON/I
OFF of 4 × 106, SS of 63 mV dec−1 (approximately), and a threshold voltage of 0.45 V, which performs better than existing devices shown in the literature. All the simulations have been performed by employing the nonequilibrium Green’s function formalism with the self-consistent solution of the Schrödinger and Poisson equations.
Simulations of single event effects in 6T2C-based ferroelectric non-volatile static random access memory
Authors: Wang Jianjian , Bi Jinshun , Liu Gang , Bai Hua , Xi Kai , Li Bo , Ji Lanlong , Majumdar Sandip
Published: October 2020

The single event effects (SEEs) on ferroelectric Hf0.5Zr0.5O2 capacitor-based non-volatile static random access memory (nvSRAM) were investigated by simulation. A nvSRAM cell integrated with two ferroelectric Hf0.5Zr0.5O2 capacitors is proposed in this study. A macro-model of the ferroelectric Hf0.5Zr0.5O2 capacitor, extracted from the real fabricated devices, is utilized for simulation analysis. Fundamental store and recall operations of the proposed nvSRAM design have been demonstrated. An independent double exponential current source was utilized and injected into specific circuit nodes to simulate the heavy ion induced single event transient current. The simulation results show that the transient pulse current is possible to upset the logic state of the memory cell from 1 to 0, but whether it can recover in a short time period after the upset errors depends on the exact value of linear energy transfer for the injected particles. In addition, increasing the remnant polarization (P
r) and decreasing the coercive voltage (V
c) and film thickness of ferroelectric capacitors can mitigate the influence of SEEs, which provides guidance for process hardening techniques aiming at space applications.