bluuebunny/crossref_metadata_2025 huggingface dataset:
Physics teacher candidates’ awareness of idealizations used in mathematical models*
Authors: Şengören Serap Kaya , Çoban Atakan , Büyükdede Mert
Published: September 2020

Equations, as mathematical models—used to explain facts—are simplified, especially when learning physics at a basic level, to help in the understanding of complex systems that depend on many variables. These simplifications are idealizations in the literature, where abstractions and approximations are also given for the same concept. When reading about a model, knowing that it is idealized, and realizing what the idealizations are, is very important in enabling the reader to understand complex operations correctly. The purpose of this study is to reveal whether or not students are aware of the idealizations used in some mathematical models to explain complex facts in physics education. This study is organized as a simple survey model. The data for the study were collected from a test consisting of 14 open-ended questions within a basic physics context. The test was given to 60 pre-service teachers studying physics and science education. The questions were prepared considering the idealizations in some mathematical models that are frequently used in physics lessons. The results of the study are given along with content analysis and frequency tables of the open-ended questions, with the help of rubrics developed by the researchers. The data obtained showed that the majority of the prospective teachers participating in the study were not aware of the idealizations in the equations, and those using the idealizations generally used irrelevant and incorrect idealizations.
Dynamic dielectric-response model of flexoelectric polarization from kHz to MHz range in an ordered assembly of BaTiO3 nanocubes
Authors: Yasui Kyuichi , Itasaka Hiroki , Mimura Ken-ichi , Kato Kazumi
Published: September 2020

Due to the strain gradient near each surface of a BaTiO3 nanocube in their ordered assembly, electric polarization appears due to flexoelectric effect. The magnitude of the flexoelectric polarization could be one order of magnitude larger than that of ferroelectric spontaneous polarization of BaTiO3. Thus, dielectric response of an assembly could be dominated by that of the flexoelectric polarization if there is no ferroelectric domain-wall motion. Numerical simulations of the dielectric response of a BaTiO3 nanocube in an ordered assembly are performed from kHz to MHz range based on a dynamic model of flexoelectric polarization assuming anharmonic potential. The calculated temperature dependence of the dielectric constant is consistent with the experimental data of high dielectric constant with nearly-flat temperature dependence. It is suggested that high dielectric constant with nearly-flat temperature dependence is not originated in ferroelectric nature of BaTiO3 nanocubes but originated in flexoelectric polarization in nanocubes which is also seen in non-ferroelectric materials.
Theoretical investigation of the scanning tunneling microscopy of Majorana bound states in topological superconductor vortices
Authors: Wu B H , Hassan S A , Gong W J , Xu X F , Wang C R , Cao J C
Published: September 2020

Scanning tunneling microscopy (STM) is an indispensable tool in detecting Majorana bound states (MBSs) in vortices of topological superconductors. By reducing the computational complexity via non-uniform grids, we systematically study the tunnel coupling as well as the temperature dependence of the differential conductance of MBSs in two dimensional devices. Numerical results show that the conductance peak approaches the quantized value 2e
2/h in strong coupling limit at low temperatures which are characteristic features of MBSs. More interestingly, a conductance local minimum in the spatially scanning is observed when the STM tip is placed at the vortex center. The dip structure can be enhanced with increased temperature or enlarged vortex size. We ascribe this observation to the sensitivity of the Andreev reflection processes of carriers at the vortex center where the thermal energy could be comparable to the vanishing pair potential. We also investigate the STM of two-vortex systems where the hybridization of the vortices can lead to oscillatory behavior of the state energy. With small inter-vortex distances, the original MBSs in vortices can merge into topologically trivial states and the conductance peak can be significantly suppressed.
Joint optimization of statistical and deep representation features for bearing fault diagnosis based on random subspace with coupled LASSO
Authors: Li XiangQi , Zhang Feng , Wang Gang , Fang Fang
Published: September 2020

In bearing fault diagnosis, statistical features and deep representation features reflect the signal characteristics from different perspectives and demonstrate tremendous diagnostic potential. Nevertheless, previous studies have paid little attention to the heterogeneousity between statistical and deep representation features. Besides, directly combining these two kinds of features may also lead to redundancy and conflict, which may negatively affect the diagnostic performance. To address this issue, an enhanced random subspace method with coupled LASSO (RS-CL) is proposed in this paper to jointly optimize statistical and deep representation features. In the feature extraction stage, statistical features are constructed from the time-domain, frequency-domain and time-frequency domain, while deep representation features are extracted by bidirectional long short-term memory. In the model construction stage, an enhanced RS-CL method is developed to generate more efficient and diverse base classifiers. To verify the performance of the proposed RS-CL method, experiments were conducted on a bearing fault diagnosis data set provided by the University of Paderborn. The experimental results verify the effectiveness and feasibility of the proposed method.
On moving hypersurfaces and the discontinuous ODE-system associated with two-phase flows
Authors: Bothe Dieter
Published: September 2020

We consider the initial value problem

x

̇

(

t

)

=
v

(

t
,
x

(

t

)

)

for
 

t
∈

(

a
,
b

)

,
x

(

t

0

)

=

x

0

which determines the pathlines of a two-phase flow, i.e. v = v(t, x) is a given velocity field of the type

v

(

t
,
x

)

=

v

+

(

t
,
x

)

if

x
∈

Ω

+

(

t

)

v

−

(

t
,
x

)

if

x
∈

Ω

−

(

t

)

with Ω±(t) denoting the bulk phases of the two-phase fluid system under consideration. The bulk phases are separated by a moving and deforming interface Σ(t) at which v can have jump discontinuities. Since flows with phase change are included, the pathlines are allowed to cross or touch the interface. Imposing a kind of transversality condition at Σ(t), which is intimately related to the mass balance in such systems, we show existence and uniqueness of absolutely continuous solutions of the above ODE in case the one-sided velocity fields v
± are continuous in (t, x) and locally Lipschitz continuous in x on their respective domain of definition. A main step in proving this result, also interesting in itself, is to freeze the interface movement by means of a particular coordinate transform which requires a tailor-made extension of the intrinsic velocity field underlying a

C

1
,
2

-family of moving hypersurfaces.
Madelung transform and probability densities in hybrid quantum–classical dynamics
Authors: Gay-Balmaz François , Tronci Cesare
Published: September 2020

This paper extends the Madelung–Bohm formulation of quantum mechanics to describe the time-reversible interaction of classical and quantum systems. The symplectic geometry of the Madelung transform leads to identifying hybrid quantum–classical Lagrangian paths extending the Bohmian trajectories from standard quantum theory. As the classical symplectic form is no longer preserved, the nontrivial evolution of the Poincaré integral is presented explicitly. Nevertheless, the classical phase-space components of the hybrid Bohmian trajectory identify a Hamiltonian flow parameterized by the quantum coordinate and this flow is associated to the motion of the classical subsystem. In addition, the continuity equation of the joint quantum–classical density is presented explicitly. While the von Neumann density operator of the quantum subsystem is always positive-definite by construction, the hybrid density is generally allowed to be unsigned. However, the paper concludes by presenting an infinite family of hybrid Hamiltonians whose corresponding evolution preserves the sign of the probability density for the classical subsystem.
Noise-induced stabilization of saddle-node ghosts
Authors: Sardanyés Josep , Raich Carles , Alarcón Tomás
Published: September 2020

It is known that saddle-node (s-n) bifurcations leave a saddle remnant (or ghost) in the region of the phase space where the annihilation of the fixed points occurred. The corresponding time delay, t
d, found right after the bifurcation is known to follow the scaling law

t

d

∼

(

ϵ
−

ϵ

c

)

−
1
/
2

, where ϵ and ϵ
c are the control parameter and its critical value, respectively. While the properties of such delays are well understood for deterministic systems, much less is known about how intrinsic noise influences this phenomenon. As a first step towards analysing this issue, in this article we explore a model with autocatalysis and a two-species hypercycle to analyse the impact of noise on delayed transitions in one- and two-dimensional dynamical systems suffering a s-n bifurcation. The first model is investigated with Gillespie simulations and the diffusion approximation, focusing on the behaviour and properties close to the bifurcation. A Fokker–Planck equation is derived, together with the stochastic potential. We show that the slowing down of the dynamics remains robust to noise. In fact, we prove both analytically and numerically that increasing noise lengthens the delays after bifurcation threshold. Furthermore, the inverse square-root scaling law is not robust to fluctuations. By contrast, scaling properties are identified in the mean extinction times as criticality is approached from above the bifurcation. This noise-induced stabilisation of the delays is also found in the two-dimensional system.
Density functional theory studies of hydrogen bonding vibrations in sI gas hydrates
Authors: Wang Hao-Cheng , Zhu Xu-Liang , Cao Jing-Wen , Qin Xiao-Ling , Yang Ye-Chen , Niu Tian-Xiao , Lu Ying-Bo , Zhang Peng
Published: September 2020

To analyze the vibrational modes of water and methane in structure I gas hydrates, we constructed a 178-atom supercell with two small cages of type 512 and six large cages of type 51262. We applied the density functional theory method to simulate the vibrational spectrum and normal modes of methane hydrates. In accord with our previous studies, we confirmed that two groups of hydrogen bond (H-bond) peaks (at around 291 and 210 cm−1) in the translational bands come from two kinds of intermolecular H-bond vibrational modes. This is the first investigation of H-bond vibrations in methane hydrates. The partial modes of CH4 were extracted. We found that the CH4 phonons in the translational region are below 180 cm−1 so that the influence of methane on the H-bond is insignificant. We proposed a new method to decompose gas hydrates via direct application of terahertz radiation to the H-bonds. Herein, we confirmed that CH4 molecules do not absorb this energy.
Design of an impeller for a fire fighting pump
Authors: Paluch Maciej , Noga Marcin
Published: September 2020

The article presents the design of a single-stage centrifugal pump impeller for use in a fire vehicle. For such a task, the set utility parameters were determined, and then several methods were used to determine the geometry and dimensions of a given impeller. The project uses A. Stepanoff’s formulas, correction of power consumption reduction (Pfleiderer coefficient), as well as the method of point selection of the width of the impeller cross-section in relation to the changing radius of the impeller. A graphical representation of the pump flow rate and pump head depending on the type of impeller and the pump characteristic speed has enabled convenient analysis in terms of assumed pump performance. The procedure adopted in the project did not require the use of advanced engineering tools. The obtained result in the form of geometry and dimensions of the designed result coincides with the parameters of the impellers used in fire pumps currently in use. In the last step of the project, a three-dimensional impeller model was developed, which is a good starting point for optimization by simulation and then experimental verification on a real object.
Adaptive Parallel Fuzzing with Multi-candidate Task Scheduling
Authors: Li Sisi , Li Ruilin , Ye Jiaxi , Tang Chaojing
Published: September 2020

Parallel fuzzing is a widely used technique for bug detection. It improves fuzzing performance by taking full advantage of the computing resource. Nevertheless, existing parallel fuzzing approaches fail to extend fuzzing optimizations of single mode to parallel mode, due to the lack of efficient information synchronization and task division. To address the challenge, researchers propose a parallel fuzzing framework that combines guiding information synchronization with task division based on branch bitmap to improve the performance of the fuzzers in parallel mode. However, when augmenting existing fuzzers with the parallel framework, we find two types of limitations caused by some mechanisms of the fuzzers, such as task scheduling mechanism. In this paper, we present an optimized parallel fuzzing approach to improve fuzzing efficiency by making valuable tasks executed as much as possible. On the one hand, we introduce a multi-candidate task scheduling mechanism, which takes multiple tasks corresponding to an input as candidates, rather than one to obtain the chances of executing tasks that are valuable but can be missed. On the other hand, we apply a synchronization information-centric design solution to some mechanisms of the fuzzers and take synchronization information as a good indicator to decide whether the parallel instances ought to shift their running mode, which can improve the adaptive ability of parallel instances and facilitate them to timely execute valuable tasks. We implement a prototype system OPAFL on top of Fairfuzz and PAFL, and evaluate its performance on several real-world software. The experimental results show that OPAFL can execute more tasks valuable and achieve higher branch coverage, compared with original parallel mode of Fairfuzz and Fairfuzz augmented with PAFL.
A Command and Control System for Air Defense Forces with Augmented Reality and Multimodal Interaction
Authors: Chen Long , Wang Wei , Qu Jue , Lei Songgui , Li Taojin
Published: September 2020

This work proposes a framework for the command and control system of air defense forces based on augmented reality technology. The system uses Microsoft HoloLens hardware as a carrier to realize the holographic display of battlefield situation information. The system can help the commander to perceive and control the situation on the battlefield in an efficient manner, in order to reduce the decision-making time of the commander. Commanders can efficiently interact with the system through gestures and voice, deploy simulated military units in the system through gestures, and send commands to weapon systems through the system. At the same time, the system also supports multi-person real-time collaborative operation, which enables the joint decision-making and sharing of commanders. This system is of great significance to improve operational efficiency and reliability, and at the same time provides an open platform for operational process planning, deduction, simulation, and verification evaluation.
English Letter Recognition Based on TensorFlow Deep Learning
Authors: Lei Wang , Xinyan Cao , Maohua Li , Jia’nan Zhao
Published: September 2020

Image recognition has always been a hot research direction. With the continuous progress of technology theory and application, deep learning has a very significant role in the field of image recognition. Today’s image international competitions and enterprise applications are mainly based on deep learning technology, compared with traditional technologies, deep learning is significantly more effective in the application of feature extraction and algorithm models. This paper based on the TensorFlow framework and use deep learning transfer learning fine-tuning to recognize handwritten English characters. In the course of the experiment, the data enhancement method is used to pre-process the collected data, which can increase the amount of training data and improve the generalization ability of the model. At the same time, the parameters and optimizer are continuously optimized to accelerate the convergence speed and finally reach the convergence loss value. Experimental results show that the application of deep learning algorithms has achieved good results in training model feature extraction and recognition accuracy.
An Image Deblurring Method Based on Improved Dark Channel Prior
Authors: Cheng Lu , Wei Haiping
Published: September 2020

The traditional dark channel priori has been successfully applied to the single image deblurring problem. According to the characteristics of the dark channel priori, clear images are recovered. However, when the fuzzy image has significant noise pollution, the dark channel prior can not play a role in the fuzzy kernel estimation. The new image denoising method based on the rational order differential inherits the advantages of the total variation denoising method which greatly improves the high frequency part of the image and the fractional order differential denoising method which can well retain the texture details of the image. In this paper, the theory of rational order differential calculation is combined with the dark channel priori of fuzzy image, and an image deblurring method based on the improved dark channel priori is proposed. The specific work is as follows: combining the maximum posterior estimation algorithm and the rational order dark channel prior, a fuzzy image model is constructed; furthermore, the model is solved by using the semi quadratic splitting method. Finally, the multi-scale iterative framework is used to estimate the fuzzy kernel of the accurate image, and then the new non blind image deblurring algorithm can be used to solve the clear image. Experimental results show that the method is effective.
Toward eliminating children’s lead exposure: a comparison of policies and their outcomes in three lead producing and using countries
Authors: Sullivan M , Green D
Published: September 2020

Though the problem of childhood lead poisoning has been recognized for more than a century, it remains an important threat to children’s health and development. This comparative policy assessment examines and compares environmental and public health policies to prevent children’s exposure of three major lead producing countries. Germany, the USA and Australia were used to explore a range of approaches primarily at the national level to identify best practice, how the lack of finding any ‘safe exposure’ level has been incorporated into policy, and to consider if any international harmonization has occurred. We searched the peer-reviewed literature, government websites, policy documents and grey literature to identify how and when policies were developed, implemented and revised. From this analysis, we present a chronology and discussion of national policy approaches for the main sources of lead exposure for children in each country. We found significant differences in timing and comprehensiveness of environmental policies related to lead. There are significant differences among the countries in biomonitoring and identifying pathways of exposure, with limited information available in Germany and Australia. Though there are significant gaps, the US has the most comprehensive regulations relating to old lead paint in housing, while in Australia, a regulatory framework is lacking. Though all three countries regulate lead in air, the US has the most health protective standard, while Australia lacks the ability to ensure that states meet the national standard. Though each country has developed regulatory frameworks for lead that have reduced children’s exposure, none of the three countries have a comprehensive set of policies that respond to the scientific evidence that there is no identified threshold for lead exposure. While there are differences in the relative importance of lead exposure pathways among the three countries, suggesting the need for different prevention emphases, there is also a strong argument for more international harmonization of exposure standards at the most protective levels. Some environmental policies incorporate current scientific understanding of lead toxicity, however, we identified gaps in standards and enforcement, and as a result, exposure continues to affect the health of children in all three countries.
Decoupling of warming mountain snowpacks from hydrological regimes
Authors: López-Moreno J I , Pomeroy J W , Alonso-González E , Morán-Tejeda E , Revuelto J
Published: September 2020

Climate warming will reduce the duration of mountain snowpacks and spring runoff, impacting the timing, volume, reliability, and sources of water supplies to mountain headwaters of rivers that support a large proportion of humanity. It is often assumed that snow hydrology will change in proportion to climate warming, but this oversimplifies the complex non-linear physical processes that drive precipitation phases and snowmelt. In this study, snow hydrology predictions made using a physical process snow hydrology model for 44 mountains areas worldwide enabled analysis of how snow and hydrological regimes will respond and interact under climate warming. The results show a generalized decoupling of mountain river hydrology from headwater snowpack regimes. Consequently, most river hydrological regimes shifted from reflecting the seasonal snowmelt freshet to responding rapidly to winter and spring precipitation. Similar to that already observed in particular regions, this study confirms that the worldwide decline in snow accumulation and snow cover duration with climate warming is substantial and spatially variable, yet highly predictable from air temperature and humidity data. Hydrological regimes showed less sensitivity, and less variability in their sensitivity to warming than did snowpack regimes. The sensitivity of the snowpack to warming provides crucial information for estimating shifts in the timing and contribution of snowmelt to runoff. However, no link was found between the magnitude of changes in the snowpack and changes in annual runoff.
Universal and optimal coin sequences for high entanglement generation in 1D discrete time quantum walks
Authors: Gratsea Aikaterini , Metz Friederike , Busch Thomas
Published: September 2020

Entanglement is a key resource in many quantum information applications and achieving high values independently of the initial conditions is an important task. Here we address the problem of generating highly entangled states in a discrete time quantum walk irrespective of the initial state using two different approaches. First, we present and analyze a deterministic sequence of coin operators which produces high values of entanglement in a universal manner for a class of localized initial states. In a second approach, we optimize the discrete sequence of coin operators using a reinforcement learning algorithm. While the amount of entanglement produced by the deterministic sequence is fully independent of the initial states considered, the optimized sequences achieve in general higher average values of entanglement that do however depend on the initial state parameters. Our proposed sequence and optimization algorithm are especially useful in cases where the initial state is not fully known or entanglement has to be generated in a universal manner for a range of initial states.
Norway’s experience in attracting human resources to the Arctic region
Authors: Simonchuk V D , Yu Nikulina A
Published: September 2020

The Arctic is an important strategic object for Russia, mainly due to the great reserves of minerals. However, the Arctic is a northern region typified by difficult working conditions. The Arctic does not have enabling environment for work in terms of climatic conditions, and remoteness from the center of the country. Consequently, the issue of attracting human capital to the Arctic region arises. Considerable involvement of the government is required to provide the population of the North with everything necessary for living, as well as to grant privileges and guarantees, taking into consideration existing international experience. At the same time, Western Arctic countries have a successful experience in human resources management. The analysis of the government programs aimed to attract and support the population of the Northern regions of Norway is carried out in this article. The most successful cases are identified; recommendations for implementation in the Russian legislation are given.
Simulation of excess nutrient solution volume of greenhouse cucumber under soilless culture
Authors: Hu Jing , Liu Zhennan , Zhuang Jianwu , Dai Bin , Liu Wei , Wang Wei , Zhang Wenhui , Zhou Yu
Published: September 2020

The prediction of excess nutrient solution volume was an essential part of re-used of nutrient solution system, and it was determined by volume of irrigation, substract, crop development stage and water content of substract. In order to found simulation model of excess nutrient solution volume, experiments were conducted at Venlo style greenhouse of Jiangsu University on 4-11, 2013. Absorption of perlite and intercept of root of nutrient solution were studied, and a simulation model of excess nutrient solution was found. Other data from different experiment was used to validate the model. The result showed that the coefficients of determination between simulated and measured value based on the 1:1 line were 0.94, and the root mean squared error between the simulated and the measured value was 5.8 mL per plant. The model could give satisfactory prediction of excess nutrient solution volume. A simulation model of excess nutrient solution was firstly found and could afford theoretical guidance to design system of re-used nutrient solution.
The effect of climate change on the climatic regionalization of wine grapes in Northeast of China
Authors: Wang Yanjun , Li Yashan , Wang Xueqiu , Fang Yulin , Liu Xu , Cui Kexu , Cui Changwei , Nan Lijun , Li Yang , Yang Junmei
Published: September 2020

Northeast China is one of the major wine-making grape bases in China. It is of great significance to study the influence of climate change on grape planting regionalization in northeast China for industrial layout and grape variety selection. According to the 168 weather stations in northeast China Daily meteorological data, calculate the frost-free period, growing season dry degree, active accumulated temperature of April to September, average annual extreme low temperature and other indicators, the 45 years from 1967 to 2011 in the northeast of grapes zoning index change trend, using GIS analysis of wine grapes in the northeast suitable cultivated area change of time and space. The results showed that the temperature increased obviously in the growing season, the indexes such as frost-free period and accumulated temperature of activity increased greatly, the suitable cultivation area of wine grapes expanded greatly to the north, and the dryness changed obviously between generations, showing a rising trend of fluctuation. The impact of climate change on viticulture varies from region to region, but overall, climate change is beneficial to wine viticulture in northeast China. The article also makes a series of Suggestions on how to use the effects of climate change to select varieties and improve wine quality.
Survey of canthaxanthin content in commercial chicken eggs sampled from Hunan province, China
Authors: He Jiang , Wu Xiangqi
Published: September 2020

Canthaxanthin (Cx) is a feed additive widely used for pigmenting egg yolk. In this study, a ultra performance liquid chromatography (UPLC) method was used to detect Cx in commercial chicken eggs sampled from Hunan province, China. Results showed that 43.75% of samples (14 out of 32) possessed detectable amount of Cx, ranging from 0.8 ± 0.2 µg/g to 152.8 ± 10.4 µg/g, and 25.0% of samples (8 out of 32) carried residues of Cx at levels higher than the approved maximum residue limit (MRL = 30.0 µg/g). Interestingly, higher detection rate and above-MRL rate were reported in samples that claimed to be free-range eggs and were collected from traditional farmers’ markets. This survey illustrates that Cx might occasionally be used in excess for breeding hens, in the surveyed area, especially in those that are not branded. Therefore, more strict regulatory measures are urgently required to be taken up by the Chinese government to retain the safety of chicken eggs and to ensure that consumers are not deceived by the color of yolks pigmented with Cx.
Chokeberry thin layer convective drying process modeling and energy efficiency estimation
Authors: Filipović V , Petković M , Filipović J , Miletić N , Durović I , Radovanović J , Lukyanov A
Published: September 2020

The effective moisture diffusivity (Deff), the energy of activation(Ea)and total energy input (Q) are appropriate parameters for modeling and energy efficiency estimation of the thin layer dehydration process of chokeberry under the different air temperature (50, 55, 60, 65 and 70 °C). Increasing the dehydration temperature will statistically significantly increased theDefffrom 2.93×10-6m2s-1(50 °C) to 7.77×10-6m2s-1(70 °C), and decreased theEi,• from 2594.77 kJ to 2474.35 kJ, respectively. As the drying temperature was increased and consecutive drying time has been reduced (from 37 hours to 23 hours), energy input statistically significantly decreased. Mathematical models showed a good correlation between calculated and experimental values and allowed good prediction of dehydration parameters, enhancing energy efficiency. TheEafor the experimental model of thin layer chokeberry dehydration was 45.37 kJ mol-1.
Improving the efficiency of greenhouses systems by developing algorithms for the synthesis of an optimal lighting spectrum based on the fundamental principles of agrophotonics
Authors: Donskoy D Yu , Klyuchka E P , Lukyanov A D
Published: September 2020

The question of creating an optimal microclimate for maximum realization of the genetically inherent potential in plants is far from being resolved. This is due to the multi-factor nature of the biotechnical system of greenhouses, the dependence on the number of controlled components of the microclimate and the consistency of their work: light, temperature, etc. Based on this task, we conducted initial research and developed additional lighting algorithms for greenhouse systems. Based on the work of previous years and existing scientific research, the most optimal method for optimizing artificial lighting and linking its intensity to the microclimatic parameters of the system has been determined.
Parametric study of the effect of hydrodynamic cavitation on cellulose in an electromechanical converter with a discrete secondary part
Authors: Kuimov D N , Minkin M S
Published: September 2020

Hydrodynamic cavitation is a very effective destructive effect on cellulose fiber. This paper presents a study of the effective parameters of the hydrodynamic cavitation process implemented by an Electromechanical Converter with a discrete secondary part for effective pretreatment of cellulose fiber.
5G tool for evaluation and comparision of energy efficiency of mobile radio channel using second-order statistics
Authors: Stefanović N , Kar A , Mladenović V
Published: September 2020

In order to increase energy efficiency over transmissions channels, common approach for optimization tasks is by means of channel’s second-order statistics. Actual channel modeling tools for 5G networks end with channel’s first-order statistics, although these metrics are not sufficient when channel conditions are rapidly changing, either in time, frequency or space. In this paper, we establish a tool for evaluation and comparision of energy efficiency of mobile radio channel using its second-order statistics, especially level crossing rate (LCR) and average fade durations (AFD), as they can implicitly pinpoint to transmission configurations that are energy efficient or, as oposit, become a waste of energy. Using both deterministic and stochastic channel modeling, we present results after simulations of Rayleigh channel for narrowband case and further extend it to passband cases, suitable for 5G scenario. We conclude about the energy efficiency of different transmission schemes used by the 5G physical layer observing LCR and AFD values.
Diffraction losses of a Fabry-Perot cavity with nonidentical non-spherical mirrors
Authors: Poplavskiy Mikhail V , Matsko Andrey B , Yamamoto Hiroaki , Vyatchanin Sergey P
Published: September 2020

Optical cavities, with both optimized resonant conditions and high quality factors, are important metrological tools. In particular, they are used for laser gravitational wave (GW) detectors. In order to have high cavity powers in GW detectors, it is necessary to suppress the parametric instability and to reduce the loss in the arm caused by point absorbers by damping the resonant conditions of harmful higher order optical modes (HOOM). This can be achieved effectively by using non spherical mirrors in symmetric Fabry–Perot (FP) cavities by increasing roundtrip losses of HOOMs Ferdous F et al 2014 Phys. Rev. A 90 033826; Matsko A et al 2016 Phys. Rev. D 93 083010. FP cavities in most of the GW detectors have non-identical mirrors to optimize clipping losses and reduce thermal noise by reducing the beam size on one side of the cavity facing to the beam splitter and recycling cavities. We present here a general method to design non spherical non-identical mirrors in non-symmetric FP cavities to damp HOOMs. The proposed design allows us to suppress the loss of the arm power caused by point absorbers on test masses.
Optical force acting on a particle in a reverse energy flow near the focus of a gradient lens
Authors: Nalimov Anton G , Stafeev Sergey S , Kotlyar Victor V
Published: September 2020

We show that if a dielectric nanoparticle (with a diameter of ∼70 nm) is placed on the optical axis near the surface (at a distance of less than 100 nm) of a high-aperture silicon gradient microlens with a refractive index in the form of a hyperbolic secant, and the lens is illuminated by laser radiation with a wavelength of 1.55 μm, then the particle is attracted to the lens surface with a force of a fraction of a piconewton. If there is a nanohole in the lens output surface, then the nanoparticle is pulled into it. This represents a kind of an ‘optical magnet.’ If a reverse energy flow is formed on the optical axis near the output surface of a gradient lens, then its presence leads to the fact that a dielectric nanoparticle with absorption will be ‘attracted’ to the surface with a greater force than a similar particle without absorption. In the absence of a reverse flow, both particles (with and without absorption) are attracted equally. We show also that in the nanohole, where the reverse energy flux is maximum, the light is right-hand circularly polarized, although the lens is illuminated by a left-hand circularly polarized light. The fields are calculated using the finite difference method in the time domain and the forces are calculated using the Maxwell stress tensor.
Study of surface photovoltage spectrum in p+-GaAs/p-GaAlAs/p-GaAs structures
Authors: Liu Jian , Chen Xinlong , Wang Honggang , Guo Yiliang , Qian Yunsheng
Published: September 2020

Surface photovoltage (SPV) in p+-GaAs/p-GaAlAs/p-GaAs has been studied by establishing a multilayer model and measuring the SPV at room temperature. The model mainly considers surface recombination velocity, interface recombination velocity and the space charge region (SCR) at the surface of p+-GaAs. The SPV of the multilayer structure is shown to originate predominantly from the minority carrier diffusion, which caused photovoltage between the surface and bottom. Subsequently, the minority carrier diffusion lengths in p+-GaAs and in p-GaAs are obtained from fitting experimental data to the theoretical model. At the same time, the minority carrier diffusion length in p-GaAs is obtained by illuminating the backside (illuminating on p-GaAs) of the p+-GaAs/p-GaAlAs/p-GaAs. The p+-GaAs in p+-GaAs/p-GaAlAs/p-GaAs structure with different thickness are measured to show the variation of SPS with different thickness, but the experimental parameters are not affected. In multi-layer structure, the SPV contributed by different layers has a great difference with different dark saturation current density.
Optimal sequencing strategies in the treatment of EGFR mutation–positive non–small cell lung cancer: Clinical benefits and cost-effectiveness
Authors: Hirsh Vera , Singh Jaspal
Published: September 2020

Purpose

To summarize current understanding of the efficacy, role, and cost-effectiveness of the available epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), and to evaluate sequencing strategies based on the available evidence.

Summary. EGFR TKIs are the current standard of care for patients with EGFR mutation–positive non–small cell lung cancer (NSCLC). Five EGFR TKIs are currently approved in the United States for use in a first-line setting; these TKIs differ in mechanism of action, efficacy, safety, and cost. Most patients develop resistance to first-line EGFR TKIs and require subsequent therapy with additional EGFR TKIs, chemotherapy, and/or other targeted agents. A major consideration when selecting EGFR TKIs, both as first-line or subsequent treatment options, is cost-effectiveness. Although clinical trials have shown that the second- and third-generation EGFR TKIs are superior in efficacy to the first-generation agents, pharmacoeconomic studies suggest that the first-generation agents are the most cost-effective, with the second-generation TKI afatinib also considered cost-effective in some studies. Despite its impressive efficacy, osimertinib appears to be less cost-effective due to substantially higher acquisition costs.

Conclusion

Preliminary data suggest that first-line afatinib followed by osimertinib may offer promising survival outcomes and, on the basis of efficacy alone, may represent an optimal sequencing strategy in the majority of patients with EGFR mutation–positive NSCLC, in particular Asian patients and those with Del19-positive tumors. However, considerably more research into outcomes and costs associated with consecutive sequencing of EGFR TKIs is needed before any conclusions can be reached.
Life-history implications of migratory Lesser Sandhill Cranes replacing adjacent blocks of primaries synchronously
Authors: Rohwer Sievert , Rohwer Vanya G , Sethi Meera Lee , HilleRisLambers Janneke
Published: September 2020

Using the patterns of fault bars in their primaries, we studied the mode of primary replacement in non-molting Lesser Sandhill Cranes (Antigone c. canadensis) salvaged from hunters in southwestern Saskatchewan. About 80% of their primaries are used for 2 yr and 20% for 3 yr. Primaries are replaced during the breeding season and are lost in synchronous blocks representing about half the primaries, suggesting that most adults probably can fly weakly during flight feather replacement. Cranes are large, aggressive birds, and this interesting, and undescribed mode of flight feather replacement seems adapted to the ability of adult cranes to defend their precocial chicks from predators. Strikingly, juvenile Sandhill Cranes showed no fault marks in their primaries, suggesting that their parents’ ability to protect them shields them from the fright of predator attacks, which, in most birds, causes fault bars to be more prevalent and strongly expressed in juveniles than adults. Adults show interesting variation in the number of primaries replaced annually, which seems likely related to whether or not they are caring for chicks. Further, single primaries may or may not be replaced preferentially, suggesting sensitivity to feather function. Evaluating these observations must await field studies of molting adults.
FGF9 is a downstream target of SRY and sufficient to determine male sex fate in ex vivo XX gonad culture
Authors: Li Yi-Han , Chen Tsung-Ming , Huang Bu-Miin , Yang Shang-Hsun , Wu Chia-Ching , Lin Yung-Ming , Chuang Jih-Ing , Tsai Shaw-Jenq , Sun H Sunny
Published: September 2020

Fibroblast growth factor 9 (FGF9) is an autocrine/paracrine growth factor that plays critical roles in embryonic and organ developments and is involved in diverse physiological events. Loss of function of FGF9 exhibits male-to-female sex reversal in the transgenic mouse model and gain of FGF9 copy number was found in human 46, XX sex reversal patient with disorders of sex development. These results suggested that FGF9 plays a vital role in male sex development. Nevertheless, how FGF9/Fgf9 expression is regulated during testis determination remains unclear. In this study, we demonstrated that human and mouse SRY bind to −833 to −821 of human FGF9 and −1010 to −998 of mouse Fgf9, respectively, and control FGF9/Fgf9 mRNA expression. Interestingly, we showed that mouse SRY cooperates with SF1 to regulate Fgf9 expression, whereas human SRY-mediated FGF9 expression is SF1 independent. Furthermore, using an ex vivo gonadal culture system, we showed that FGF9 expression is sufficient to switch cell fate from female to male sex development in 12–16 tail somite XX mouse gonads. Taken together, our findings provide evidence to support the SRY-dependent, fate-determining role of FGF9 in male sex development.
Corridors of Clarity: Four Principles to Overcome Uncertainty Paralysis in the Anthropocene
Authors: Polasky Stephen , Crépin Anne-Sophie , Biggs Reinette (Oonsie) , Carpenter Stephen R , Folke Carl , Peterson Garry , Scheffer Marten , Barrett Scott , Daily Gretchen , Ehrlich Paul , Howarth Richard B , Hughes Terry , Levin Simon A , Shogren Jason F , Troell Max , Walker Brian , Xepapadeas Anastasios
Published: September 2020

Global environmental change challenges humanity because of its broad scale, long-lasting, and potentially irreversible consequences. Key to an effective response is to use an appropriate scientific lens to peer through the mist of uncertainty that threatens timely and appropriate decisions surrounding these complex issues. Identifying such corridors of clarity could help understanding critical phenomena or causal pathways sufficiently well to justify taking policy action. To this end, we suggest four principles: Follow the strongest and most direct path between policy decisions on outcomes, focus on finding sufficient evidence for policy purpose, prioritize no-regrets policies by avoiding options with controversial, uncertain, or immeasurable benefits, aim for getting the big picture roughly right rather than focusing on details.
Transparency in Social Work: A Critical Exploration and Reflection
Authors: Devlieghere Jochen , Gillingham Philip
Published: September 2020

Social work is a mostly discursive practice, comprised of the verbal and written interactions between service users, social workers, social work managers and supervisors and numerous external agencies. The words used to describe service users and service delivery are therefore important. These words change over time, and new words come into use. With the introduction of New Public Management, new concepts and ideas were introduced to social work service delivery and practice and new words became embedded in the social work lexicon. One of the new words that emerge in both the authors’ research with social work agencies is ‘transparency’. In this article, a critical thematic analysis of the meanings of transparency as it is used in recent social work research literature and commentary is presented. Transparency is explored in relation to how it is used, when it is used, by whom and in relation to what (and who), from the macro-level of social work agencies and governments to the micro-level of individuals as practitioners and service users. In problematising transparency, a rationale for future research is proposed about what transparency means, and could mean, in the context of social services provision and, in particular, for service users.
ELF and teacher education: attitudes and beliefs
Authors: Dewey Martin , Pineda Inmaculada
Published: September 2020

The growing relevance of research in English as a lingua franca (ELF) for ELT has led to a need to rethink the way we approach English in the language classroom and to reassess how we configure knowledge about language in teacher education. This article reports on a joint project initiated in 2017 at King’s College London (UK) and the University of Malaga (Spain), exploring the value of perceptions towards language and ELF among language teachers. Our goal was to promote reflective attitudes towards linguistic diversity, language change and the potential impact of ELF on developments in ELT. We present here the results of an online survey that participants took after only two sessions into their training. Our findings link ELT practitioners’ teaching priorities to an ELF orientation because there was a higher number of participants who aligned with statements about pedagogic approaches where successful communication is emphasized above accuracy (42/72), and statements that favour fostering experimentation with linguistic forms (53/72) and promoting students’ L1 sociocultural identity (54/72).
Development and validation of a questionnaire to assess Unaccompanied Migrant Minors’ needs (AEGIS-Q)
Authors: Di Pietro Maria Luisa , Zaçe Drieda , Sisti Leuconoe Grazia , Frisicale Emanuela Maria , Corsaro Alice , Gentili Andrea , Giraldi Luca , Bruno Stefania , Boccia Stefania
Published: September 2020

Background

While many studies focus on specific aspects of Unaccompanied Migrant Minors’ (UMMs) health, especially mental well-being, there is a lack of tools comprehensively assessing their needs. To fill this gap, we developed and validated a questionnaire to thoroughly assess unAccompaniEd miGrant mInorS’ physical, psychological, legal, spiritual, social and educational needs (AEGIS-Q).

Methods

This work consisted of three stages. The first one involved an extensive literature review. Given the results of the review, a first draft of the questionnaire was developed and submitted to a panel of experts for validation (Delphi method-second stage). During the third stage, the final version of the questionnaire was pilot-tested in a sample of 18 UMMs.

Results

The questionnaire, drafted based on the results of the review, consisted of sections covering personal data, migration profile, physical health needs and access to healthcare, psychological needs, legal needs, spiritual needs and educational and social needs of UMMs. After two Delphi rounds, the final version of the questionnaire, consisting of 83 questions, was structured. The pilot study had a response rate of 89–100%. We found substantial reliability for most of the sections in the questionnaire, including physical health (α=0.652), legal (α=0.781), and educational and social (α=0.614) needs. The questions regarding psychological needs had very high reliability (α=0.860).

Conclusions

The questionnaire offers a useful sharable tool to assess and monitor UMMs’ needs, helping the reception system to better know and meet their needs and implement the taking in charge.