bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative characterization of dielectric properties of polymer fibers and polymer composites using electrostatic force microscopy
Authors: Yurchenko Ilya , Jayasekara Anuja S , Cebe Peggy , Staii Cristian 
Published: September 2020

Abstract
We use a new method based on electrostatic force microscopy (EFM) to perform quantitative measurements of the dielectric constants of individual electrospun nanofibers of poly(L-lactic acid) (PLLA), as well as composite fibers of PLLA with embedded multiwall carbon nanotubes (MWCNT-PLLA). The EFM data record the oscillation phase of an atomic force microscope (AFM) cantilever as a function of the AFM tip position. In our experiments the relative dielectric constants ϵ of the sample are measured from the EFM phase shifts vs. the tip-surface separation, according to a simple analytical model describing the tip-surface interactions. We perform a comprehensive study of how the dielectric constant depends on the fiber diameter for both electrospun PLLA and MWCNT/PLLA fiber composites. Our measurements show that EFM can distinguish between dielectric properties of PLLA fibers and fiber composites with different diameters. Dielectric constants of both PLLA and MWCNT-PLLA composite fibers decrease with increasing fiber diameter. In the limit of large fiber diameters (D > 100 nm), we measure dielectric constants in the range: ϵ = 3.4–3.8, similar to the values obtained for unoriented PLLA films: ϵfilm
= 2.4–3.8. Moreover, the dielectric constants of the small diameter MWCNT-PLLA composites are significantly larger than the corresponding values obtained for PLLA fibers. For MWCNT-PLLA nanofiber composites of small diameters (D < 50 nm), ϵ approaches the values measured for neat MWCNT: ϵCN
= 12 ± 2. These results are consistent with a simple fiber structural model that shows higher polarizability of thinner fibers, and composites that contain MWCNTs. The experimental method has a high-resolution for measuring the dielectric constant of soft materials, and is simple to implement on standard atomic force microscopes. This non-invasive technique can be applied to measure the electrical properties of polymers, interphases, and polymer nanocomposites.
Measuring anisotropy of elastic wave velocity with ultrasound imaging and an autofocus method: application to cortical bone
Authors: Renaud Guillaume , Clouzet Pierre , Cassereau Didier , Talmant Maryline 
Published: September 2020

Abstract
This work investigates the feasibility of estimating the parameters of an exact transverse isotropy model in cortical bone. The model describes the anisotropy of the velocity of compressional and shear bulk elastic waves. We propose to achieve this with ultrasound imaging relying on the transmission of unfocused beams and with an autofocus method. The latter is based on the principle that the reconstructed ultrasound image shows optimal quality if the velocity model is correct. The autofocus approach is applied to a composite image of the interface between cortical bone and marrow. It is obtained by incoherent summation of four types of images exploiting four different ray paths in the cortical bone layer, three of them involving mode-converted shear waves. If the parameters of the model are correct, spatial co-localization of the interface appears in the four images. As a result, intensity and sharpness in the composite image are maximal.
The five parameters of the model of transverse isotropy are successfully estimated in a tube made of a bone-mimicking material. The estimates are in good agreement with resonant ultrasound spectroscopy (RUS) measurements. The tube thickness is recovered with an error smaller than 0.3%. In vivo results at the forearm of a volunteer are promising, four parameters could be estimated and are in good agreement with ex vivo RUS measurements. Moreover x-ray peripheral computed tomography corroborates the thickness of the cortical bone layer in the ultrasound image. Weak-anisotropy and exact transverse isotropy models provide very close measurements of the thickness of the tube and the radius bone. Thus, we recommend using the model of weak transverse isotropy for real-time anatomical imaging because more computationally efficient. For material characterization however, the model of exact transverse isotropy is preferred because the elastic anisotropy of cortical bone is moderate, rather than weak.
Frequency-dependent analysis of ultrasound apparent absorption coefficient in multiple scattering porous media: application to cortical bone
Authors: Yousefian Omid , Karbalaeisadegh Yasamin , Muller Marie 
Published: September 2020

Abstract
The effect of matrix viscoelastic absorption on frequency-dependent attenuation in porous structures mimicking simplified cortical bone is addressed in this numerical study. An apparent absorption is defined to quantify the difference between total attenuation (resulting from both absorption and scattering) and attenuation exclusively due to scattering. A power-law model is then used to describe the frequency-dependent apparent absorption as a function of pore diameter and density. The frequency response of the porous structures to a Gaussian pulse is studied to determine the frequency range over which the system can be considered linear. The results show that for low scattering regimes (normalized frequency

<

0.80), the system and its apparent absorption can be considered linear. Hence, the total attenuation coefficient results from the summation of scattering and absorption coefficients. However, for highly scattering regimes, the system can no longer be considered linear, as the apparent absorption vs. frequency deviates from a linear trend. As the pore density increases, the apparent absorption coefficient increases as well.
Multidimensional modeling of non-equilibrium plasma generated by a radio-frequency corona discharge
Authors: Cruccolini Valentino , Scarcelli Riccardo , Battistoni Michele , Grimaldi Carlo Nazareno , Dal Re Massimo Augusto , Breden Douglas , Raja Laxminarayan L 
Published: September 2020

Abstract
Low-temperature plasma (LTP) ignition concepts rely on the production of radical and charged species to speed up the onset of combustion in spark-ignition engines. These features are responsible for the superior performance of LTP igniters under extremely dilute combustion operation that is not achievable by conventional spark igniters. Additionally, LTP discharges extend the lifetime of the igniters, due to the avoidance of spark processes. For these reasons, the engine research community and the automotive industry have shown growing interest in this technology in the recent years. As of today, computational fluid-dynamics (CFD) codes typically used by the multi-dimensional engine modeling community do not have reliable models to describe LTP ignition processes. One key missing piece of information is the physical and chemical properties of the plasma and their effect on combustion ignition. Most non-equilibrium plasma simulations reported in literature are based on simplified, canonical geometries, with simple discharge excitation schemes. In this paper we conduct multi-dimensional modeling of the non-equilibrium plasma generated by an application-relevant radio-frequency (RF) corona discharge in air. Three test cases are simulated, characterized by different environmental pressure levels and peak electrode voltage values at room temperature. Streamer penetration, electron number density, atomic oxygen production, and bulk gas temperature distribution in the first 10 sinusoidal pulses are presented and discussed. This model can be used as a key tool for an in-depth understanding of RF-corona discharge for automotive applications and provides the basis for future implementations of dedicated LTP ignition models in CFD codes.
An optoelectronic notch (‘dip’) phenomenon in the heterodyne photocarrier radiometry frequency response of Si wafers: a route to quantitative trap-state dynamic processes in semiconductors
Authors: Song Yaqin , Mandelis Andreas , Melnikov Alexander , Sun Qiming 
Published: September 2020

Abstract
An anomaly was observed in the heterodyne photocarrier radiometry (HePCR) frequency response of Si wafers in the form of a signal amplitude depression (‘dip’) accompanied by a 180° phase transition. This phenomenon resembles an electronic notch filter and was investigated experimentally and theoretically by invoking free-carrier-density-wave (CDW) kinetics in generic semiconductor systems. Both homodyne PCR and HePCR signals were obtained from n- and p-type wafers of different resistivities. Dynamic nonlinear rate-equation models with two bandgap carrier traps were introduced and analytical zeroth and first-order CDW solutions were obtained in the frequency domain. The experimental frequency responses of the HePCR optoelectronic notch phenomenon were found to be in very good agreement with the theory. Characteristic CDW recombination and trap capture and emission characteristic times were obtained and studied as functions of the illuminating laser intensity. The present newly observed HePCR notch phenomenon has revealed a new mechanism of nonlinear contributions due to trap-state-related CDW dynamics in semiconductors superposed on the well-known nonlinear electron-hole recombination interactions that give rise to non-zero HePCR signals. The implications of this notch phenomenon are discussed in terms of its importance in providing physical insights into photocarrier dynamic interactions with traps, leading to identification of active CDW trap-state numbers and precision measurements of their kinetic parameters, carrier capture and emission coefficients, and quantitative trap densities that determine the optoelectronic quality of semiconductors.
Stable two-dimensional soliton complexes in Bose–Einstein condensates with helicoidal spin–orbit coupling
Authors: Kartashov Y V , Sherman E Ya , Malomed B A , Konotop V V 
Published: September 2020

Abstract
We show that attractive two-dimensional (2D) spinor Bose–Einstein condensates with helicoidal spatially periodic spin–orbit coupling (SOC) support a rich variety of stable fundamental solitons and bound soliton complexes. Such states exist with chemical potentials belonging to the semi-infinite gap in the band spectrum created by the periodically modulated SOC. All these states exist above a certain threshold value of the norm. The chemical potential of fundamental solitons attains the bottom of the lowest band, whose locus is a ring in the space of Bloch momenta, and the radius of the non-monotonous function of the SOC strength. The chemical potential of soliton complexes does not attain the band edge. The complexes are bound states of several out-of-phase fundamental solitons whose centers are placed at local maxima of the SOC-modulation phase. In this sense, the impact of the helicoidal SOC landscape on the solitons is similar to that of a periodic 2D potential. In particular, it can compensate repulsive forces between out-of-phase solitons, making their bound states stable. Extended stability domains are found for complexes built of two and four solitons (dipoles and quadrupoles, respectively). They are typically stable below a critical value of the chemical potential.
Electromagnetic trap for polar particles
Authors: Przybylska Maria , Maciejewski Andrzej J , Yaremko Yurij 
Published: September 2020

Abstract
A novel design for an electromagnetic trap is proposed for confinement of neutral particles having a permanent electric dipole moment. The device uses a combination of a sextupole electric and quadrupole magnetic fields superimposed with a strong constant electric field perfectly aligned along the z-axis. We use the extended dipole model to study the dynamics of particle in this position dependent electromagnetic field. The motion of the centre of mass of the dipole is nonlinearly coupled with its rotation. We find three families of particular solutions for which the orbits are periodic or quasiperiodic. They correspond to the particular cases when the whole energy is accumulated in either translational or rotational degrees of freedom. Stability analysis of chosen particular solutions provides trapping conditions. We present several numerical simulations which illustrate trapping and confinement of an electric dipole in the proposed trap. These simulations were performed for three kinds of polar particles and various fields selections. We hope that the proposed model allows experimental physicists to apply a wide variety of non-destructive methods for manipulation, detection and analysis of trapped particles.
An analytical velocity field of spiral tips in reaction–diffusion systems
Authors: Pan De-Bei , Li Bing-Wei , Pan Jun-Ting , Li Qi-Hao , Zhang Hong 
Published: September 2020

Abstract
Spiral waves are ubiquitous in diverse physical, chemical, and biological systems. The tip (phase singularity) of a spiral wave is considered to represent its organizing center. Here, we derive an analytical velocity field of spiral tips based on the variables of a general two-variable reaction–diffusion (RD) equation. From this velocity field, we can predict the velocities of spiral tips at time t as long as the values of the variables are given at that time. Numerical simulations with two-variable RD models are in quantitative agreement with the analytical results. Furthermore, we also demonstrate the velocity field of spiral tips in the Luo–Rudy model for cardiac excitation.
Retraction: Environmental Indicators through Artificial Neural Networks (Journal of Physics: Conference Series
1432 012049)
Authors: Silva Jesús , Naveda Alexa Senior , Palma Hugo Hernández , Núñez William Niebles , Rodríguez Luis Jiménez 
Published: September 2020

Published 15 September 2020
This article, and others within this volume, has been retracted by IOP Publishing following clear evidence of plagiarism and citation manipulation.
This work was originally published in Spanish (1) and has been translated and published without permission or acknowledgement to the original authors. IOP Publishing Limited has discovered other papers within this volume that have been subjected to the same treatment. This is scientific misconduct.
Misconduct investigations are ongoing at the author’s institutions. IOP Publishing Limited will update this notice if required once those investigations have concluded. To date, there is no evidence to suggest anyone other than Amelec Viloria / Jesus Silva was directly culpable for the actions that led to retraction.
IOP Publishing Limited request any citations to this article be redirected to the original work (1).
Anyone with any information regarding these papers is requested to contact conferenceseries@ioppublishing.org.
Retraction: Natural Language Explanation Model for Decision Trees (Journal of Physics: Conference Series
1432 012074)
Authors: Silva Jesús , Palma Hugo Hernández , Núñez William Niebles , Ruiz-Lazaro Alex , Varela Noel 
Published: September 2020

Published 15 September 2020
This article, and others within this volume, has been retracted by IOP Publishing following clear evidence of plagiarism and citation manipulation.
This work was originally published in Spanish (1) and has been translated and published without permission or acknowledgement to the original authors. IOP Publishing Limited has discovered other papers within this volume that have been subjected to the same treatment. This is scientific misconduct.
Misconduct investigations are ongoing at the author’s institutions. IOP Publishing Limited will update this notice if required once those investigations have concluded. To date, there is no evidence to suggest anyone other than Amelec Viloria / Jesus Silva was directly culpable for the actions that led to retraction.
IOP Publishing Limited request any citations to this article be redirected to the original work (1).
Anyone with any information regarding these papers is requested to contact conferenceseries@ioppublishing.org.
Retraction: Neural Networks for the Web Services Classification (Journal of Physics: Conference Series
1432 012076)
Authors: Silva Jesús , Naveda Alexa Senior , Movilla José Solórzano , Núñez William Niebles , Palma Hugo Hernández 
Published: September 2020

Published 15 September 2020
This article, and others within this volume, has been retracted by IOP Publishing following clear evidence of plagiarism and citation manipulation.
This work was originally published in Spanish (1) and has been translated and published without permission or acknowledgement to the original authors. IOP Publishing Limited has discovered other papers within this volume that have been subjected to the same treatment. This is scientific misconduct.
Misconduct investigations are ongoing at the author’s institutions. IOP Publishing Limited will update this notice if required once those investigations have concluded. To date, there is no evidence to suggest anyone other than Amelec Viloria / Jesus Silva was directly culpable for the actions that led to retraction.
IOP Publishing Limited request any citations to this article be redirected to the original work (1).
Anyone with any information regarding these papers is requested to contact conferenceseries@ioppublishing.org.
Nuclear Astrophysics in underground laboratories: the LUNA experiment
Authors: Caciolli Antonio 
Published: September 2020

Abstract
One of the main ingredients of nuclear astrophysics is the knowledge of the thermonuclear reactions responsible for powering the stellar engine and for the synthesis of the chemical elements. At astrophysical energies the cross section of nuclear processes is extremely reduced by the effect of the Coulomb barrier. The low value of cross sections for charged particles prevents their measurement at stellar energies on Earth surface and often extrapolations are needed. The Laboratory for Underground Nuclear Astrophysics (LUNA) is placed under the Gran Sasso mountain and thanks to the cosmic-ray background reduction provided by its position can investigate cross sections at energies close to the Gamow peak in stellar scenarios. Many crucial reactions involved in hydrogen burning have been measured directly at astrophysical energies with both the LUNA-50kV and the LUNA-400kV accelerators, and this intense work will continue with the installation of a MV machine able to explore helium and carbon burnings. Based on this progress, currently there are efforts in several countries to construct new underground accelerators. In this talk, the typical techniques adopted in underground nuclear astrophysics will be described and the most relevant results achieved by LUNA will be reviewed. The exciting science that can be probed with the new facilities will be highlighted.
Search for second order response of nuclei to isospin probes and their connection to double beta decay
Authors: Cappuzzello F. 
Published: September 2020

Abstract
In order to get quantitative information on neutrino absolute mass scale from the possible measurement of the 0νββ decay half-lives, the knowledge of the Nuclear Matrix Elements (NME) involved in such transitions is mandatory. NMEs are not observables and can only be accessed by theory. However, the many-body nature of the nuclear state involved in the decay, makes this task possible only at approximate level. In this perspective, several experimental approaches have been proposed in the years in order to provide useful information to better constrain the theory. Here a short overview of the role of charge exchange reactions in this scenario is given, with particular emphasis on second order processes, known as Double Charge Exchange (DCE) reactions.
Results on quantum phase transitions within the semimicroscopic algebraic cluster model and extension to deformed clusters
Authors: Lohr-Robles D S , López-Moreno E , Hess P O 
Published: September 2020

Abstract
The properties of quantum phase transitions in the semimicroscopic algebraic cluster model are investigated. The order of the quantum phase transition is shown to depend on the path taken in the parameter space and a novel procedure to obtain the Maxwell set separatrix is discussed. The first steps toward a description of systems of deformed cluster and heavy nuclei are presented.
Agricultural decision making and climate uncertainty in developing countries
Authors: Waldman Kurt B , Todd Peter M , Omar Shahera , Blekking Jordan P , Giroux Stacey A , Attari Shahzeen Z , Baylis Kathy , Evans Tom P 
Published: September 2020

Abstract
In situations of uncertainty, people often make decisions with heuristic shortcuts or decision rules, rather than using computational or logical methods such as optimizing their behavior based on specific goals. The high level of uncertainty and complexity involved in adapting to climate change suggests that heuristics would be commonly used in this context rather than more structured decision methods. Through a systematic review of 137 articles, from 2007–2017 we explore the behavioral and cognitive assumptions used to examine agricultural decision-making related to climate change among farmers in developing countries. We find a strong orientation toward modeling behavior and decision making as a rational utility-maximizing process, despite decades of research demonstrating the prevalence of simpler heuristic choice when facing uncertainty and real-world constraints. Behavioral and cognitive approaches can increase our ability to predict or explain decisions being made in this realm, particularly in terms of how we understand decision making around information processing and risk assessment. In the following review, we highlight articles that have contributed to developing a more realistic decision-making framework for studying this problem on the ground. While there is a burgeoning literature using psychological insights to examine decision making under climate uncertainty, few studies consider the prevalence of simple heuristics, the presence of cognitive biases, and the salience of climate relative to other risk factors.
Observed changes in flood hazard in Africa
Authors: Tramblay Yves , Villarini Gabriele , Zhang Wei 
Published: September 2020

Abstract
Floods represent a major natural hazard in Africa, causing over 27 000 fatalities during the period 1950–2019. Despite its relevance, little is known about changes in flood hazard across this continent due to the lack of long-term high-quality streamflow records. Here we use a newly assembled discharge dataset of African rivers, and provide a long-term comprehensive view of flood hazard across this continent. We show that the annual maximum peak discharge does not exhibit a monotonic pattern, but overall decreasing trends prior to 1980 and increasing trends afterwards, especially in western and southern Africa. Our results indicate that these differing trends can be ascribed to changes in extreme precipitation around 1980. Moreover, these changes in intense precipitation pre/post 1980 are due to increased thunderstorm activity associated with enhanced convective available potential energy and zonal vertical shear driven by cooling temperature trends over western Africa. The changes in flood hazard in southern Africa can be tied to changes in Namibia low-level jet. Therefore, the observed increase in flooding since 1980 suggests that it would be beneficial to improve the monitoring, modeling and communication of flood hazard to reduce the socio-economic impacts of these events.