bluuebunny/crossref_metadata_2025 huggingface dataset:
Non-Newtonian rheology in inertial suspensions of inelastic rough hard spheres under simple shear flow
Authors: Gómez González Rubén , Garzó Vicente
Published: July 2020

Non-Newtonian transport properties of an inertial suspension of inelastic rough hard spheres under simple shear flow are determined by the Boltzmann kinetic equation. The influence of the interstitial gas on rough hard spheres is modeled via a Fokker–Planck generalized equation for rotating spheres accounting for the coupling of both the translational and rotational degrees of freedom of grains with the background viscous gas. The generalized Fokker–Planck term is the sum of two ordinary Fokker–Planck differential operators in linear v and angular ω velocity space. As usual, each Fokker–Planck operator is constituted by a drag force term (proportional to v and/or ω) plus a stochastic Langevin term defined in terms of the background temperature Tex. The Boltzmann equation is solved by two different but complementary approaches: (i) by means of Grad’s moment method and (ii) by using a Bhatnagar–Gross–Krook (BGK)-type kinetic model adapted to inelastic rough hard spheres. As in the case of smooth inelastic hard spheres, our results show that both the temperature and the non-Newtonian viscosity increase drastically with an increase in the shear rate (discontinuous shear thickening effect) while the fourth-degree velocity moments also exhibit an S-shape. In particular, while high levels of roughness may slightly attenuate the jump of the viscosity in comparison to the smooth case, the opposite happens for the rotational temperature. As an application of these results, a linear stability analysis of the steady simple shear flow solution is also carried out showing that there are regions of the parameter space where the steady solution becomes linearly unstable. The present work extends previous theoretical results (H. Hayakawa and S. Takada, “Kinetic theory of discontinuous rheological phase transition for a dilute inertial suspension,” Prog. Theor. Exp. Phys. 2019, 083J01 and R. G. González and V. Garzó, “Simple shear flow in granular suspensions: Inelastic Maxwell models and BGK-type kinetic model,” J. Stat. Mech. 2019, 013206) to rough spheres.
Evolutionary reinforcement learning of dynamical large deviations
Authors: Whitelam Stephen , Jacobson Daniel , Tamblyn Isaac
Published: July 2020

We show how to bound and calculate the likelihood of dynamical large deviations using evolutionary reinforcement learning. An agent, a stochastic model, propagates a continuous-time Monte Carlo trajectory and receives a reward conditioned upon the values of certain path-extensive quantities. Evolution produces progressively fitter agents, potentially allowing the calculation of a piece of a large-deviation rate function for a particular model and path-extensive quantity. For models with small state spaces, the evolutionary process acts directly on rates, and for models with large state spaces, the process acts on the weights of a neural network that parameterizes the model’s rates. This approach shows how path-extensive physics problems can be considered within a framework widely used in machine learning.
Heat-transfer analysis of a transitional boundary layer over a concave surface with Görtler vortices by means of direct numerical simulations
Authors: Méndez M. , Shadloo M. S. , Hadjadj A.
Published: July 2020

This work studies the development of a thermal boundary layer during the laminar-to-turbulent transition process over a concave surface. Direct numerical simulations are performed where the temperature variable is treated as a passive scalar. The laminar flow is perturbed with wall-roughness elements that are able to produce centrifugal instabilities in the form of Görtler vortices with a maximum growth rate. It is found that Görtler vortices are able to greatly modify the surface heat-transfer by generating a spanwise periodic distribution of temperature. Similar to the Görtler momentum boundary layer, elongated mushroom-like structures of low-temperature are generated in the upwash region, whereas in the downwash region, the thermal boundary layer is compressed. Consequently, temperature gradients are increased and decreased in the downwash and upwash regions, respectively, thereby generating an overall enhancement of the heat-transfer rate of ∼400% for the investigated Prandtl numbers (Pr = 0.72, Pr = 1, and Pr = 7.07). This enhancement surpasses the turbulent heat-transfer values during the transitional region, characterized by the development of secondary instabilities. However, downstream, the heat-transfer rate decays to the typical turbulent values. Streamwise evolution of several thermal quantities such as temperature wall-normal distribution, thermal boundary layer thickness, and Stanton number is reported in different regions encountered in the transition process, namely, linear, nonlinear, transition, and fully turbulent regions. These quantities are reported locally at upwash and downwash regions, where they present minima and maxima, as well as globally as spanwise-averaged quantities. Furthermore, it is found that the Reynolds analogy between streamwise-momentum and heat-transfer holds true throughout the whole transition process for the Pr = 1 case. Moreover, the turbulent thermal boundary layer over a concave surface is analyzed in detail for the first time. The viscous sub-layer and the log-law region are described for each investigated Pr. Besides, the root-mean-squared temperature fluctuations are computed, finding that its wall-normal distribution exhibits a higher peak when Pr is increased.
Efficient hot-electron extraction in two-dimensional semiconductor heterostructures by ultrafast resonant transfer
Authors: Li Yujie , Zhou Hongzhi , Chen Yuzhong , Zhao Yida , Zhu Haiming
Published: July 2020

Energy loss from hot-carrier cooling sets the thermodynamic limit for the photon-to-power conversion efficiency in optoelectronic applications. Efficient hot-electron extraction before cooling could reduce the energy loss and leads to efficient next generation devices, which, unfortunately, is challenging to achieve in conventional semiconductors. In this work, we explore hot-electron transfer in two-dimensional (2D) layered semiconductor heterostructures, which have shown great potential for exploring new physics and optoelectronic applications. Using broadband micro-area ultrafast spectroscopy, we firmly established a type I band alignment in the WS2–MoTe2 heterostructure and ultrafast (∼60 fs) hot-electron transfer from photoexcited MoTe2 to WS2. The hot-electron transfer efficiency increases with excitation energy or excess energy as a result of a more favorable continuous competition between resonant electron transfer and cooling, reaching 90% for hot electrons with 0.3 eV excess energy. This study reveals exciting opportunities of designing extremely thin absorber and hot-carrier devices using 2D semiconductors and also sheds important light on the photoinduced interfacial process including charge transfer and generation in 2D heterostructures and optoelectronic devices.
Purcell enhancement of a deterministically coupled quantum dot in an SU-8 laser patterned photonic crystal heterostructure
Authors: Shao H. , Ying G. , Lennon S. A. , Brossard F. S. F. , Griffiths J. P. , Nuttall L. P. , Osokin V. , Clarke E. , He H. , Taylor R. A.
Published: July 2020

Enhancement of single photon source emission through cavity quantum electrodynamics is key to the realization of applicable emitters in many quantum optics technologies. In this work, we present a flexible and convenient cavity fabrication process that writes a SU-8 microstrip onto a photonic crystal waveguide deterministically, in which InGaAs/GaAs quantum dots are present as emitters. The strip cavity is laser patterned at the location of a quantum dot with a chosen emission wavelength. Micro-photoluminescence studies are undertaken, which demonstrate an enhanced emission intensity by a factor of 2.1 with weak coupling to a single quantum dot, and time-resolved photoluminescence further shows a Purcell enhancement factor of 2.16. The fabrication process is, thus, verified as a reliable recipe to introduce deterministic cavity coupling to a chosen quantum dot.
Spin transport at a Pt/InAs quantum well interface using spin Hall and Rashba effects
Authors: Jeon Jeehoon , Kim Seong Been , Kim Taeyueb , Lee OukJae , Han Suk Hee , Kim Hyung-jun , Koo Hyun Cheol , Hong Jinki
Published: July 2020

In the field of spintronics, charge-to-spin conversion without a ferromagnetic material has attracted intense interest from researchers seeking to realize a fully electrical spin device because this design obviates the need for magnetic field control of magnetization. Instead of spin injection from a ferromagnetic source, spin-Hall-induced pure spin current has recently attracted considerable interest for transferring spin information into the semiconductor channel. In the present work, the spin is injected from a platinum electrode via the direct spin Hall effect and is subsequently detected in a strong Rashba channel via the inverse spin Hall effect. Before being detected, the spin state is modulated by a gate voltage; the signal observed with various channel lengths and gate voltages demonstrates this Rashba precessional modulation. The addition of Zeeman precession induced by an external magnetic field provides the signal-elucidating definite spin motion in the channel and clear interplay between the Rashba and Zeeman processions. Our approach opens a fascinating possibility for realizing a ferromagnet-free system for use in low-power and high-temperature spin transistors.
The influence of heat load on Merino sheep. 3. Cytokine and biochemistry profiles
Authors: Lees A. M. , Wijffels G. , McCulloch R. , Stockwell S. , Owen H. , Sullivan M. L. , Olm J. C. W. , Cawdell-Smith A. J. , Gaughan J. B.
Published: July 2020

Context
Approximately 2 million sheep are exported from Australia on live export voyages annually. As voyages travel from a southern hemisphere winter to a northern hemisphere summer, production and welfare issues associated with excessive heat load may arise.

Aims
The aim of this study was to evaluate the responses of sheep to incremental heat load under simulated live export conditions, specifically the influence of heat load on the metabolic and inflammatory status of sheep.

Methods
A total of 144 Merino wethers (44.02 ± 0.32 kg) were used in a 29-day climate controlled study using two cohorts of 72 sheep (n = 2), exposed to two treatments: (1) thermoneutral, and (2) hot. Sheep in the hot treatment were exposed to heat load simulated from live export voyages from Australia to the Middle East. Blood samples were collected from all sheep (n = 144) on Day 1, then at 7-day intervals (n = 5) for the duration of each 29-day period. Blood samples were analysed to determine the cytokine, biochemistry and haematology (data not presented here) profiles. Cytokine and biochemical profiles were analysed using a repeated measures model assuming a compound symmetry covariance. The model fitted included terms for cohort and treatment (hot, thermoneutral), and a term for sample collection day (day) and a treatment × day interaction. The subject factor corresponded to the cohort × treatment combinations.

Key results
There were no consistent trends in plasma cytokine and biochemical profiles. Bicarbonate was the only parameter that was influenced by cohort (P = 0.0035), treatment (P = 0.0025), collection (P = 0.0001) and treatment × collection (P = 0.0025). Furthermore, interleukin-6 and glutamate dehydrogenase were the only parameters that were not influenced by cohort (P > 0.295), treatment (P = 0.2567), collection (P > 0.06) or treatment × collection (P = 0.34).

Conclusions
Overall, these data highlight that the metabolic and inflammatory status of sheep exposed to incremental heat load, during a simulated live export voyage from a southern hemisphere winter to a northern hemisphere summer, were not markedly altered.

Implications
These results provide a preliminary evaluation of the inflammatory and metabolic status of sheep on arrival in the Middle East.
Creep behaviour of equiaxed fine-grain γ-TiAl-based alloy prepared by powder metallurgy
Authors: Duan Zhenxin , Han Ying , Song Xiaolei , Chen Hua
Published: July 2020

In this study, γ-TiAl-based alloy with chemical composition of Ti–45Al–5Nb (in at.-%) fabricated by powder metallurgy method was crept at 700°C under 200–500 MPa. The creep properties and the microstructure after creep tests were investigated. The results showed that the γ-TiAl-based alloy was composed of equiaxed γ-TiAl grains and α2-Ti3Al grains with average sizes of 1.4 and 0.5 μm, respectively. The creep resistance deteriorated generally with increased applied stresses. The typical intergranular fracture characteristics were observed though the grains were small. The calculated stress exponent and activation energy revealed the main creep mechanism of grain boundary sliding. Furthermore, twinning and dynamic recrystallisation also led to the creep deformation.
Dendritic cells release exosomes together with phagocytosed pathogen; potential implications for the role of exosomes in antigen presentation
Authors: Lindenbergh Marthe F. S. , Wubbolts Richard , Borg Ellen G. F. , van ’T Veld Esther M. , Boes Marianne , Stoorvogel W.
Published: July 2020

Dendritic cells (DC) have the unique capacity to activate naïve T cells by presenting T cell receptor specific peptides from exogenously acquired antigens bound to Major Histocompatibility Complex (MHC) molecules. MHC molecules are displayed on the DC plasma membrane as well as on extracellular vesicles (EV) that are released by DC, and both have antigen‐presenting capacities. However, the physiological role of antigen presentation by EV is still unclear. We here demonstrate that the release of small EV by activated DC is strongly stimulated by phagocytic events. We show that, concomitant with the enhanced release of EV, a significant proportion of phagocytosed bacteria was expulsed back into the medium. High‐resolution fluorescence microscopic images revealed that bacteria in phagosomes were surrounded by EV marker‐proteins. Moreover, expulsed bacteria were often found associated with clustered HLA II and CD63. Together, these observations suggest that exosomes may be formed by the inward budding into phagosomes, whereupon they are secreted together with the phagosomal content. These findings may have important implications for selective loading of peptides derived from phagocytosed pathogens onto exosome associated HLA molecules, and have important implications for vaccine design.
Liver X receptors are required for thymic resilience and T cell output
Authors: Chan Christopher T. , Fenn Ashley M. , Harder Nina K. , Mindur John E. , McAlpine Cameron S. , Patel Jyoti , Valet Colin , Rattik Sara , Iwamoto Yoshiko , He Shun , Anzai Atsushi , Kahles Florian , Poller Wolfram C. , Janssen Henrike , Wong Lai Ping , Fernandez-Hernando Carlos , Koolbergen David R. , van der Laan Anja M. , Yvan-Charvet Laurent , Sadreyev Ruslan I. , Nahrendorf Matthias , Westerterp Marit , Tall Alan R. , Gustafsson Jan-Ake , Swirski Filip K.
Published: July 2020

The thymus is a primary lymphoid organ necessary for optimal T cell development. Here, we show that liver X receptors (LXRs)—a class of nuclear receptors and transcription factors with diverse functions in metabolism and immunity—critically contribute to thymic integrity and function. LXRαβ-deficient mice develop a fatty, rapidly involuting thymus and acquire a shrunken and prematurely immunoinhibitory peripheral T cell repertoire. LXRαβ’s functions are cell specific, and the resulting phenotypes are mutually independent. Although thymic macrophages require LXRαβ for cholesterol efflux, thymic epithelial cells (TECs) use LXRαβ for self-renewal and thymocytes for negative selection. Consequently, TEC-derived LXRαβ protects against homeostatic premature involution and orchestrates thymic regeneration following stress, while thymocyte-derived LXRαβ limits cell disposal during negative selection and confers heightened sensitivity to experimental autoimmune encephalomyelitis. These results identify three distinct but complementary mechanisms by which LXRαβ governs T lymphocyte education and illuminate LXRαβ’s indispensable roles in adaptive immunity.
GULFMET key comparison of DC voltage at 1.018 V and 10 V
Authors: Yang Steven , Tsui CM , Solve Stephane , Kim Kyu-Tae , Calija Srdan , Bartholomew Jon , Alrobaish Abdullah
Published: July 2020

This report presents the GULFMET key comparison (GULFMET.EM.BIPM-K11) results of DC voltages at the 1.018 V and 10 V with two travelling electronic DC reference standards. This comparison was supported by the BIPM and GULFMET associate members, KRISS and SCL, which are from the APMP. The linking difference from the BIPM.EM-K11 KCRV was calculated. The agreement between participating laboratories is good, which could support GULFMET participating laboratories in submitting new calibration and measurement capability entries.

Main text

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Calibration of thermocouples from 419,527 °C (freezing point of Zn) up to 1492 °C (melting point of the Pd-C eutectic), by the temperature fixed point and comparison methods
Authors: Campo D del , Abdelaziz Y , Anagnostou M , Arifovic N , Bergerud R A , Bojkovski J , Ciocarlan E , Edler F , Elliot C , Hathela O , Hodzic N , Holmsten M , Iacomini L , Kozicki M , Nedialkov S , Sadli M , Simic S , Strnad R , Turzó-András E
Published: July 2020

This report present the results of the EURAMET inter-comparison carried out to compare the calibration of thermocouples from 419,527 °C (freezing point of Zn) up to 1492 °C (melting point of the Pd-C eutectic). This inter-comparison is intended to be used to support the calibration and measurement capabilities (CMCs) of the participants in the calibration of thermocouples.

The comparison was organized in three loops with nineteen participating laboratories and it allowed the performance of the measurement either in fixed points and/or by comparison. The method used to analyse the results of the comparison was the generalized weighted mean that takes into account the full covariance matrix that includes correlations between the participants which have similar traceability sources and between measurements performed by the same laboratory (i.e. the pilots that performed measurements at the beginning and at the end of each loop and the measurements performed by the same laboratory in fixed points and by comparison at the same calibration point).

Main text

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
An undergraduate laboratory experiment to build and characterize a thermionic triode for use as an audio amplifier
Authors: Murray Andrew James , Cunane Peter , Harvey Matthew
Published: July 2020

Although largely superseded by transistors for small signal amplification, the thermionic valve (or tube) still finds use in high-fidelity audio amplifiers, in guitar amplifiers and in high-power radio and television transmitters, where their power to size scalability has advantages over solid state devices. In the undergraduate experiments detailed here students construct a triode inside a vacuum chamber, and investigate the effects of different designs on signal gain. The characteristics of their triodes are measured to determine the optimal condition for signal amplification. The triode is then used to amplify an audio signal to determine the frequency response, and they can listen to the results via headphones using an input signal of their choice. This experiment hence introduces students to vacuum technology, to electron beams and to analog electronics.
Extended Falicov–Kimball model: Hartree–Fock vs DMFT approach
Authors: Kapcia Konrad Jerzy , Lemański Romuald , Zygmunt Marcin Jakub
Published: July 2020

In this work, we study the extended Falicov–Kimball model at half-filling within the Hartree–Fock approach (HFA) (for various crystal lattices) and compare the results obtained with the rigorous ones derived within the dynamical mean field theory (DMFT). The model describes a system, where electrons with spin-↓ are itinerant (with hopping amplitude t), whereas those with spin-↑ are localized. The particles interact via on-site U and intersite V density–density Coulomb interactions. We show that the HFA description of the ground state properties of the model is equivalent to the exact DMFT solution and provides a qualitatively correct picture also for a range of small temperatures. It does capture the discontinuous transition between ordered phases at U = 2V for small temperatures as well as correct features of the continuous order–disorder transition. However, the HFA predicts that the discontinuous boundary ends at the isolated-critical point (of the liquid-gas type) and it does not merge with the continuous boundary. This approach cannot also describe properly a change of order of the continuous transition for large V as well as various metal–insulator transitions found within the DMFT.
Facile synthesis of CuCo2O4@NiCo2O4 hybrid nanowire arrays on carbon cloth for a multicomponent non-enzymatic glucose sensor
Authors: Liu Shilin , Zeng Wen , Guo Qi , Li Yanqiong
Published: July 2020

The design of hierarchical heterogeneous structures with rational components is considered as a promising method to enhance the properties of electrocatalyst. Binary metal oxides, with high electrochemical activity, have attracted considerable interest in glucose determination. In this work, we synthesized the CuCo2O4@NiCo2O4 hybrid structure on conductive carbon cloth (CC) via a simple two-step hydrothermal process and investigated its catalytic ability toward glucose. The two individual components that make up this hybrid electrode have good electrical conductivity and excellent catalytic properties for glucose, so the smart combination of these two active materials can provide more catalytic sites and sufficient redox couples for the glucose oxidation. As a result, the CuCo2O4@NiCo2O4 modified CC presented superior glucose sensing properties, including ultrahigh sensitivity, fast response time, wide linear range and acceptable detection limit. Besides, the sample also exhibited good selectivity for substances in human blood that interfere with glucose detection, such as UA, AA, fructose, sucrose and KCl. The potential of the CuCo2O4@NiCo2O4/CC electrode for practical application was investigated by measuring the glucose concentration in real serum samples. These results prove that the construction of hierarchical ordered structure is conducive to the improvement of glucose sensor.
Comment on ‘Improvements for drift-diffusion plasma fluid models with explicit time integration’
Authors: Zou Jiayong
Published: July 2020

Recently, J Teunissen reported a fully explicit method, namely the current-limit approach, which claimed to overcome the dielectric relaxation time restriction for the drift-diffusion plasma fluid model. In this comment, we point out that the current-limit approach is not mathematically consistent, and discuss about the possible reason why the inconsistency was not visibly noticed.
Formation and propagation of ionization waves during ns pulse breakdown in plane-to-plane geometry
Authors: Orr Keegan , Yang Xin , Gulko Ilya , Adamovich Igor V
Published: July 2020

Ionization wave development during ns pulse breakdown in nitrogen between two parallel plate, dielectric-covered electrodes is studied by ps electric field induced second harmonic (EFISH) generation and kinetic modeling. The results indicate formation of two well-defined ionization waves in the discharge gap, which requires a relatively high initial electron density. The first, anode-directed, wave is produced by ‘sweeping’ the initial electrons by the applied voltage pulse. The second wave originates between the cathode and the first wave front, due to the field enhancement in this region, generating two wave fronts propagating in opposite directions and observed in plasma emission images. Only the anode-directed front of the second wave is detected by the EFISH measurements, most likely due to the proximity of the cathode-directed front to the wall. Both the measurements and the modeling predictions exhibit a transient electric field overshoot in the center of the gap, caused by the anode-directed front of the second wave. The boundary between the plasma domains formed ahead of the first wave and behind the second wave, observed in the plasma emission images, is detected by the EFISH measurements and predicted by the modeling calculations. The electron density and coupled energy distributions predicted by the model at the end of the discharge pulse are nearly uniform, except near the cathode-adjacent wall, where the applicability of the present model is uncertain and which is not accessible to the EFISH measurements.
Development of multi-layered electromagnetic system for improving base isolator using a magnetorheological elastomer
Authors: Hwang Yongmoon , Lee Junghoon , Kye Seungkyung , Jung Hyung-Jo
Published: July 2020

Magnetorheological elastomer (MRE) is one of the smart materials whose stiffness and damping ratios can be controlled by applying a magnetic field. Several studies have been conducted on the utilization of MREs as base isolators in semi-active systems. A base isolator using a MRE utilizes an electromagnetic system to generate a magnetic field for the MRE. Generally, single-layered electromagnetic systems are used in MRE-based isolators. The single-layered electromagnetic system forms an inter-space between the MRE and the electromagnetic system to consider the deformation of the MRE. A larger inter-space is observed when the strain of the MRE is increased, which causes limitations owing to the excessive volume and electric power of the base isolator. Therefore, a electromagnetic system is proposed to overcome these limitations, in which the single-layered electromagnetic system is divided into several layers and behaves according to the deformation of the MRE. To validate the superiority of the proposed electromagnetic system, numerical analyses were conducted, using ANSYS Electronics, to compare its magnetic flux density, resistance, size, and volume. Based on the results of these analyses, dynamic characteristic tests were performed to compare the MR effects in each system.
Shape memory alloy actuator with active cooling device and deflectable winglet application
Authors: Mao Zhiwen , Xu Zhiwei , Wang Qi
Published: July 2020

Heating and cooling time directly influence the response speed of a shape memory alloy (SMA) wire actuator. An SMA wire is heated quickly by electric current, however quickly cooling it to a given temperature is difficult. In this study, we proposed a pipeline-type active air convection cooling scheme, which uses compressed air as cooling airflow to achieve rapid active cooling of SMA wire actuators. We designed an SMA wire linear actuator consisting of SMA wires, a compressed air tank, an air valve, an Outlet Pipeline, an SMA Cooling Pipeline, and some other additional accessories. We established theoretical models of heat transfer under natural cooling and active convection cooling of an SMA wire. In addition, we carried out theoretical simulation and experiments on a NiTi alloy SMA wire with a diameter of 1 mm and compared the accuracy of simulation with test results. The SMA wire actuators are used for deflectable morphing winglets of aircraft wing. We designed three-dimensional numerical models of the morphing winglets that can be deflected within ±20° and the experimental models are machined and assembled. Final test results show that active cooling time is reduced by more than 70% compared with natural cooling and the response speed is improved significantly.
Interleaved intramuscular stimulation with minimally overlapping electrodes evokes smooth and fatigue resistant forces
Authors: Eladly Ahmed , Del Valle Jaume , Minguillon Jesus , Mercadal Borja , Becerra-Fajardo Laura , Navarro Xavier , Ivorra Antoni
Published: July 2020

Objective. It is known that multi-site interleaved stimulation generates less muscle fatigue compared to single-site synchronous stimulation. However, in the limited number of studies in which intramuscular electrodes were used, the fatigue reduction associated with interleaved stimulation could not consistently be achieved. We hypothesize that this could be due to the inability to place the intramuscular electrodes used in interleaved stimulation in locations that minimize overlap amongst the motor units activated by the electrodes. Our objective in the present study was to use independent intramuscular electrodes to compare fatigue induced by interleaved stimulation with that generated by synchronous stimulation at the same initial force and ripple. Approach. In the medial gastrocnemius muscle of an anesthetized rabbit (n = 3), ten intramuscular hook wire electrodes were inserted at different distances from the nerve entry. Overlap was measured using the refractory technique and only three electrodes were found to be highly independent. After ensuring that forces obtained by both stimulation modalities had the same ripple and magnitude, fatigue induced during interleaved stimulation across three independent distal electrodes was compared to that obtained by synchronously delivering pulses to a single proximal electrode. Main results. Contractions evoked by interleaved stimulation exhibited less fatigue than those evoked by synchronous stimulation. Twitch force recruitment curves collected from each of the ten intramuscular electrodes showed frequent intermediate plateaus and the force value at these plateaus decreased as the distance between the electrode and nerve entry increased. Significance. The results indicate that interleaved intramuscular stimulation is preferred over synchronous intramuscular stimulation when fatigue-resistant and smooth forces are desired. In addition, the results suggest that the large muscle compartments innervated by the primary intramuscular nerve branches give rise to progressively smaller independent compartments in subsequent nerve divisions.
Experimental validation of inventory simulations on molybdenum and its isotopes for fusion applications
Authors: Gilbert M.R. , Packer L.W. , Stainer T.
Published: July 2020

Molybdenum is a potential material for future nuclear fusion experiments and power plants. It has good thermo-mechanical properties and can be readily fabricated, making it attractive as an alternative material to tungsten (the current leading candidate) for high neutron flux and high thermal load regions of fusion devices. Unfortunately, exposure to fusion neutrons is predicted to cause significant radioactivity in elemental Mo for decades and centuries after exposure, which would be a problem during maintenance and decommissioning operations. Simulation predictions indicate that Mo activation could be reduced by isotopic adjustment (biasing). If these predictions are proven and validated, and if isotopic adjustment is technically and economically feasible, then Mo could be used in future demonstration and commercial reactors without significantly increasing the amount of long-term, higher-level radioactive waste.

Transmutation (inventory) simulations used to predict activation rely on nuclear reaction data. The quality of these data impact on the confidence and uncertainty associated with predictions. Recently, UKAEA has developed benchmarks to test and validate the FISPACT-II inventory code and the input nuclear data libraries. Verification of molybdenum inventory simulations is performed against experimental decay-heat measurements from JAEA’s fusion neutron source (FNS) facility and using new data acquired from γ-spectroscopy measurements of Mo irradiated in the ASP 14 MeV facility in the UK.

Results demonstrate that FISPACT-II predictions (with TENDL-2019 nuclear data) for Mo are accurate on the short-timescales (minutes, hours of irradiation and minutes, days, weeks of cooling) of these laboratory experiments. However, these kinds of experiments are limited in their coverage of the important radionuclides for decay radiation from Mo on the years, decades and beyond timescales. Further experiments with fusion relevant conditions and timescales, potentially with alternative measurement techniques, are still needed.
Periodic quantum graphs with predefined spectral gaps
Authors: Khrabustovskyi Andrii
Published: July 2020

Let Γ be an arbitrary

Z

n

-periodic metric graph, which does not coincide with a line. We consider the Hamiltonian

H

ε

on Γ with the action −ɛ
−1d2/dx
2 on its edges; here ɛ > 0 is a small parameter. Let

m
∈
N

. We show that under a proper choice of vertex conditions the spectrum

σ

(

H

ε

)

of

H

ε

has at least m gaps as ɛ is small enough. We demonstrate that the asymptotic behavior of these gaps and the asymptotic behavior of the bottom of

σ

(

H

ε

)

as ɛ → 0 can be completely controlled through a suitable choice of coupling constants standing in those vertex conditions. We also show how to ensure for fixed (small enough) ɛ the precise coincidence of the left endpoints of the first m spectral gaps with predefined numbers.
Silicon waveguides with graphene: coupling of waveguide mode to surface plasmons
Authors: Čtyroký Jiří , Petráček Jiří , Kuzmiak Vladimír , Kwiecien Pavel , Richter Ivan
Published: July 2020

Silicon waveguides with graphene layers have been recently intensively studied for their potential as fast and low-power electro-optic modulators with small footprints. In this paper we show that in the optical wavelength range of 1.55 μm, surface plasmons supported by the graphene layer with the chemical potential exceeding ∼0.5 eV can couple with the guided mode of the silicon waveguide and affect its propagation. On the other hand, this effect might be possibly utilized in technical applications like a very low-power amplitude modulation, temperature sensing, etc.
Confocal laser scanning microscopy as a real-time quality-assessment tool for industrial graphene synthesis
Authors: Kim Dong Jin , Lee Chang-Won , Suh Yeonjoon , Jeong Heejeong , Jo Insu , Moon Joonhee , Park Mina , Woo Yun Sung , Hong Byung Hee
Published: July 2020

For the industrial quality control (QC) of the chemical vapor deposition (CVD) graphene, it is essential to develop a method to screen out unsatisfactory graphene films as efficiently as possible. However, previously proposed methods based on Raman spectroscopy or optical imaging after chemical etching are unable to provide non-invasive and fast analysis of large-area graphene films as grown on Cu foil substrates. Here we report that the reflection mode of confocal laser scanning microscopy (CLSM) provides a high-contrast image of graphene on Cu, enabling the real-time evaluation of the coverage and quality of graphene. The reflectance contrast, Rc, was found to be dependent on the incident laser wavelength, of which the maximum was obtained at 405 nm. In addition, Rc decreases with increasing defect density of graphene. The dependence of Rc on the graphene’s quality and laser wavelengths were explained by the tight-binding model calculation based on the Fresnel’s interference formula. Thus, we believe that the reflection mode CLSM would be a very powerful quality-assessment tool for the mass production of CVD graphene films grown on Cu.
Impact of mating system on range size and niche breadth inEpipactis(Orchidaceae)
Authors: Evans Alexandra , Jacquemyn Hans
Published: July 2020

Background and Aims

The geographical distribution of plant species is linked fundamentally not only to environmental variables, but also to key traits that affect the dispersal, establishment and evolutionary potential of a species. One of the key plant traits that can be expected to affect standing genetic variation, speed of adaptation and the capacity to colonize and establish in new habitats, and therefore niche breadth and range size, is the plant mating system. However, the precise role of the mating system in shaping range size and niche breadth of plant species remains unclear, and different studies have provided contrasting results. In this study, we tested the hypothesis that range size and niche breadth differed with mating system in the orchid genus Epipactis.

Methods

We modelled the ecological niches of 14 Epipactis species in Europe using occurrence records and environmental satellite data in Maxent. Niche breadth and niche overlap in both geographic and environmental space were calculated from the resulting habitat suitability maps using ENMTools, and geographic range was estimated using α-hull range definition. Habitat suitability, environmental variable contributions and niche metrics were compared among species with different mating systems.

Key Results

We did not detect significant differences in niche breadth, occurrence probability or geographical range between autogamous and allogamous Epipactis species, although autogamous species demonstrated notably low variation in niche parameters. We also found no significant differences in niche overlap between species with the same mating system or different mating systems. For all Epipactis species, occurrence was strongly associated with land cover, particularly broad-leafed and coniferous forests, and with limestone bedrock.

Conclusions

These results suggest that the mating system does not necessarily contribute to niche breadth and differentiation, and that other factors (e.g. mycorrhizal specificity) may be more important drivers of range size and niche breadth in Epipactis and orchids in general.
Recent hybrid speciation at the origin of the narrow endemicPulmonaria helvetica
Authors: Grünig Sandra , Fischer Markus , Parisod Christian
Published: July 2020

Background and Aims

Hybridization is known to drive plant speciation through the establishment of homoploid or allopolyploid hybrid species. Here we investigate the origin of Pulmonaria helvetica, a narrow endemic species described across a restricted area of Switzerland that was entirely covered by ice during the last glacial maximum. This species presents an original number of chromosomes (2n = 24) and morphological traits suggestive of a hybrid origin.

Methods

We sequenced a plastid locus and 1077 double-digest restriction-site-associated DNA (ddRAD) loci in 67 individuals from across the distribution range of P. helvetica and candidate progenitor species growing in the same area. Assignment of genotypes to main genetic clusters within and among taxa using STRUCTURE tested whether P. helvetica represents a genetically differentiated lineage and addressed the hypothesis of its hybrid origin. Comparative ecological modelling further addressed possible niche differentiation among taxa.

Key Results

Pulmonaria helvetica was highlighted as a genetically homogeneous species distinct from co-occurring taxa. Consistent with a scenario of hybrid speciation, it presented clear evidence of balanced admixture between Pulmonaria officinalis (2n = 16) and Pulmonaria mollis s.l. (2n = 18, 22), which was also highlighted as a maternal progenitor based on plastid sequences. Limited genetic structure within the maternal progenitor is consistent with an origin of P. helvetica through either homoploid hybridization with considerable karyotype changes or via complex scenarios of allopolyploidy involving a dysploid taxon of P. mollis s.l. Comparative niche modelling indicated non-significant ecological differences between P. helvetica and its progenitors, supporting intrinsic factors resulting from hybridization as main drivers of speciation.

Conclusions

Hybridization appears as a major process having promoted the postglacial origin of the narrow endemic P. helvetica, suggesting hybrid speciation as an effective process that rapidly produces new species under climate changes.
Nut and peanut butter intake and the risk of colorectal cancer and its anatomical and molecular subtypes: the Netherlands Cohort Study
Authors: Nieuwenhuis Lisette , Simons Colinda C J M , Weijenberg Matty P , van den Brandt Piet A
Published: July 2020

Nut intake has been associated with reduced total cancer-related mortality, but evidence for colorectal cancer (CRC) risk is inconclusive. We investigated the associations between nut and peanut butter intake and anatomical CRC subtypes. To account for molecular heterogeneity, associations between nut and peanut butter intake and colorectal tumors harboring APC, KRAS or BRAF mutations, p53 overexpression or microsatellite instability were examined in secondary analyses. In the Netherlands Cohort Study (n = 120 852), lifestyle habits were measured with a questionnaire in 1986. After 20.3 years follow-up, 3567 CRC cases were included in case–cohort analyses. For the analyses of molecular CRC subtypes, 574 cases were included after 7.3 years follow-up. In categorical analyses, total nut intake was not significantly associated with CRC [HR (95% CI) 10+ g/day versus non-consumers = 0.94(0.78–1.15) in men; 0.96(0.75–1.22) in women]. In restricted cubic spline analyses, significant non-linear inverse associations with rectal cancer were observed for total nut, peanut and peanut butter intake in women, and borderline significant non-linear inverse associations for total nut and peanut intake in men. Regarding the molecular CRC subtypes, peanut butter intake was significantly associated with an increased risk of colorectal tumors that did not develop through the serrated neoplasia pathway in men [HR (95% CI) per 5 g/day increment = 1.22(1.07–1.38)]. Nut and peanut butter intake are non-linearly inversely associated with rectal cancer risk in women. In men, nut intake is borderline significantly non-linearly associated with a reduced rectal cancer risk. Peanut butter is associated with an increased risk of colorectal tumors that do not develop through the serrated neoplasia pathway in men.
The Long Shadow of Youth: Girls’ Transition From Full-Time Education and Later-Life Subjective Well-Being in the English Longitudinal Study of Ageing
Authors: Xue Baowen , Tinkler Penny , McMunn Anne
Published: July 2020

Objectives

To investigate whether the timing and nature of women’s transitions out of full-time (FT) education are related to later-life subjective well-being and the life-course experiences that might explain any associations seen.

Methods

Data are from women in Wave 3 of the English Longitudinal Study of Ageing who have participated in the life history interview and were aged 50+ at the interview (n = 3,889). Using multichannel sequence analysis, we identified 6 types of transition out of FT education (ages 14–26). Regression models were used to examine associations between transition types and life satisfaction, quality of life, and depressive symptoms at age 50+.

Results

Women who made early transitions to married parenthood and FT domestic labor had lower levels of well-being on all 3 later-life well-being outcomes (p < .01), compared to women who made later transitions to family life and remained employed. Women who remained single up to age 26 also had lower life satisfaction (p < .05) and quality of life (p < .01) in later life than their counterparts who married and had children. These associations were explained by the life-course socioeconomic and relationship pathways. Advantaged childhood socioeconomic circumstances and higher educational qualifications set “Later Marriage and Later employment” women apart onto advantaged trajectories and a better quality of life later (p < .01).

Discussion

The timing and nature of exits from FT education played a pivotal role in setting people onto life-course trajectories that influence well-being in later life for this older generation of women.
Emerging roles of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate as regulators of multiple steps in autophagy
Authors: Baba Takashi , Balla Tamas
Published: July 2020

Inositol phospholipids are low-abundance regulatory lipids that orchestrate diverse cellular functions in eukaryotic organisms. Recent studies have uncovered involvement of the lipids in multiple steps in autophagy. The late endosome–lysosome compartment plays critical roles in cellular nutrient sensing and in the control of both the initiation of autophagy and the late stage of eventual degradation of cytosolic materials destined for elimination. It is particularly notable that inositol lipids are involved in almost all steps of the autophagic process. In this review, we summarize how inositol lipids regulate and contribute to autophagy through the endomembrane compartments, primarily focusing on PI4P and PI(4,5)P2.
The dynamics of the nuclear environment and their impact on gene function
Authors: Zannino Lorena , Casali Claudio , Siciliani Stella , Biggiogera Marco
Published: July 2020

In the last decades, it has become increasingly clear how the modulation of spatial organization of chromatin over time and through the cell cycle is closely connected to gene function regulation. Different physicochemical stimuli contribute to the realization of specific transcriptional programs and finally to a specific cellular phenotype. In this review, we aim to describe the current knowledge about the dynamics regulating the movements and the interactions of molecules within the nucleus and their impact on gene functions. In particular, taking into account that these forces exert their effect in a nuclear environment characterized by a high concentration of molecules, we will discuss the role of proteins and structures that regulate these movements and transduce physicochemical signals acting on the cell to the nucleus.
Affirming Radical Equality in the Context of COVID-19: Human Rights of Older People and People with Disabilities
Authors: Akerkar Supriya
Published: July 2020

This paper discusses the impact of COVID-19 on older people and people with disabilities. It draws attention to the violations of their human rights in the context of COVID-19 which in turn reveal the hierarchical social order of our society. Although statistics show higher deaths of older people in regard to COVID-19, these numbers co-exist with rampant discrimination towards these groups with underlying messaging that their lives are dispensable. The paper highlights violations at different levels—discursive, ethical, and everyday—and shows how they are underpinned by ageism and disablism which stereotype older people and people with disabilities with prejudicial messaging and actions by states and societal actors. At the same time, the paper also highlights the value of human rights discourses and instruments which are mobilized by the disability movement and groups upholding the rights of older people, to question these rights infringements in the context of COVID-19. The politics of these groups which call for principled equality and inclusion of older people and people with disabilities in times of COVID-19 exhibit a much-needed disruption of our social order, an undertaking that needs to be continued in COVID-19 times and after.