bluuebunny/crossref_metadata_2025_split huggingface dataset:
A classical, non-singular, bouncing universe
Authors: Güngör Özenç , Starkman Glenn D. 
Published: April 2021

Abstract
We present a model for a classical, non-singular bouncing cosmology without violation of the null energy condition (NEC). The field content is General Relativity plus a real scalar field with a canonical kinetic term and only renormalizable, polynomial-type self-interactions for the scalar field in the Jordan frame. The universe begins vacuum-energy dominated and is contracting at t=-∞. We consider a closed universe with a positive spatial curvature, which is responsible for the universe bouncing without any NEC violation. An Rϕ2 coupling between the Ricci scalar and the scalar field drives the scalar field from the initial false vacuum to the true vacuum during the bounce. The model is sub-Planckian throughout its evolution and every dimensionful parameter is below the effective-field-theory scale MP, so we expect no ghost-type or tachyonic instabilities. This model solves the horizon problem and extends co-moving particle geodesics to past infinity, resulting in a geodesically complete universe without singularities. We solve the Friedman equations and the scalar-field equation of motion numerically, and analytically under certain approximations.
Quintessential α-attractor inflation: forecasts for Stage IV galaxy surveys
Authors: Akrami Yashar , Casas Santiago , Deng Senwen , Vardanyan Valeri 
Published: April 2021

Abstract
Single-field models of α-attractor quintessential inflation provide a unified picture of the two periods of early- and late-time cosmic acceleration, where both inflation and dark energy are described by a single scalar degree of freedom rolling down a runaway potential. These theoretically well-motivated models have distinct observational predictions that are in agreement with existing cosmological data. We show that the next generation of large-scale structure surveys, even when no other cosmological data sets are considered, will strongly constrain the parameter space of these models, and test them against the standard cosmological model and more conventional non-quintessential inflation. In particular, we expect 𝒪(10-5-10-4) constraints on the present values of the dark energy equation of state and its time derivative, w0 and wa. We also forecast more than one order of magnitude tighter constraints on the spectral index of primordial curvature perturbations n_s compared to the expectations for the standard model. This demonstrates the powerful synergy between the upcoming large-scale structure probes of inflation and those aiming to measure the tensor-to-scalar ratio r through the observation of B-mode polarization of the cosmic microwave background.
Practical amplification for a single photon qudit encoded in three degrees of freedom
Authors: Zhang Jie , Xu Bao-Wen , Zhou Lan , Zhong Wei , Sheng Yu-Bo 
Published: April 2021

Abstract
A single-photon qudit encoded in more than one degree of freedom (DOF) can effectively enlarge a single photon’s capacity and has great potential for applications in future high-capacity quantum communication fields. During the photon transmission in practical noisy channels, photon qudits may suffer from photon transmission loss, which largely limits their application. In this paper, we propose a practical noiseless linear amplification (NLA) protocol for protecting the single-photon qudit encoded in polarization and double-longitudinal momentum DOFs. This NLA adopts the imperfect entangled state generated from a practical spontaneous parametric down-conversion (SPDC) source as the auxiliary state and can be realized under current experimental conditions. After performing the NLA protocol, the fidelity of the target single-photon qudit can be increased and the encoded information in all DOFs can be well preserved. We show the adoption of the imperfect entangled state generated from SPDC source is superior to that of the imperfect single-photon state from

a

practical heralded single-photon source. Our NLA protocol has application potential in current and future quantum communications.
Steering-induced coherence in decoherence channels
Authors: Xiong Shao-Jie , Zhang Lu-Hong , Liu Jin-Ming , Sun Zhe 
Published: April 2021

Abstract
We study steering-induced coherence (SIC) in local decoherence channels. Two types of channels are considered in this work, one is the amplitude damping channel under rotating-wave approximation (RWA) and the other the non-RWA channel. Unlike the amplitude damping channel, the system-environment interaction of the non-RWA channel is treated without RWA. We use the hierarchy equation method to calculate the dynamical evolution of SIC and B-side measurement-induced disturbance (MID). For the two channels, SIC decreases with time monotonically or oscillatingly due to the decoherence effect. Moreover, the different behavior of SIC between the two channels are also shown through the numerical results. SIC and MID obviously exhibit more oscillatory behavior in the non-RWA channel compared with the cases in the RWA channel. In some regions of system-environment coupling, the value of SIC (MID) in the non-RWA channel is larger than that in the RWA channel. However, in the strong non-Markovian regions, SIC (MID) drops to zero in the RWA channel, while it does not happen in the non-RWA channels. Additionally, we find that SIC can be generated from the states without entanglement.
Millimeter-wave beam scattering and induced broadening by plasma turbulence in the TCV tokamak
Authors: Chellaï O. , Alberti S. , Furno I. , Goodman T. , Maj O. , Merlo G. , Poli E. , Ricci P. , Riva F. , Weber H. 
Published: April 2021

Abstract
The scattering of millimeter-wave beams from electron density fluctuations and the associated beam broadening are experimentally demonstrated. Using a dedicated setup, instantaneous deflection and (de-)focusing of the beam due to density blobs on the beam path are shown to agree with full-wave simulations. The detected time-averaged wave power transmitted through the turbulent plasma is reproduced by the radiative-transfer model implemented in the WKBeam code, which predicts a ∼50% turbulence-induced broadening of the beam cross-section. The role of core turbulence for the considered geometry is highlighted.
Screen-Printed Resistive Pressure Sensors: Influence of Electrode Geometry on the Performance and on Cross-Sensitivity to Strain and Temperature
Authors: Gräbner Daniel , Tintelott Marcel , Schön Kevin , Lang Walter 
Published: April 2021

Abstract
Fully screen-printed resistive pressure sensors have attracted rising attention in recent years. The possibility to fabricate them on any substrate as well as their low thickness and overall flexibility allow their application on curved surfaces or for material integrated sensing. However, these applications often apply additional loads other than only pressure to the sensors. A major concern is the cross-sensitivity of the sensors to strain. Thus, this work investigates the influence of the electrode geometry used for screen-printed pressure sensors on the device performance and on the cross-sensitivity to strain. It is shown, that the performance as well as the cross-sensitivity to strain are affected by electrode setup and orientation. The pressure sensitivity increases with the number of interdigital electrodes. The cross-sensitivity to temperature is not affected by the electrode setup.
DRIE Si Nanowire Arrays Supported Nano-Carbon Film for Deriving High Specific Energy Supercapacitors On-Chip
Authors: Lu Pai , Chen Xuyuan , Ohlckers Per , Halvorsen Einar , Hoffmann Martin , Müller Lutz 
Published: April 2021

Abstract
Supercapacitor is a promising solution to storage of pulsed energy generated by MEMS energy harvesting systems, relying on its faster charging/discharging capability than secondary battery. To improve the energy density of on-chip supercapacitor which shows potential for integration with MEMS devices, in this paper we first present a successful electrode design for high specific energy pseudo-supercapacitors on the basis of deep reactive ion etched Si nanowire array supported nano-carbon matrix. Widely used pseudo-capacitive manganese oxide active material is facilely deposited into the conductive nano-carbon matrix by a chemical bath deposition. The derived electrode exhibits a remarkable capacitance increase (around 4.5x enhancement) compared with the nano-carbon matrix benefiting from the contribution of pseudo-capacitive manganese oxide. Assembled sandwich prototype on-chip supercapacitors with a symmetric configuration offer a high specific capacitance of 741.6 mF cm−2 when discharged at 1 mA cm−2, and the energy density can attain as high as 51.5 μWh cm−2. The achieved high specific energy makes such on-chip supercapacitors attractive in the field of energy collection when cooperated with micro-or nano-energy generators.
Design and Simulation of a Scalable Hybrid Energy Harvesting Device for Low Frequency Rotations
Authors: Schlögl Matthias , Schneider Michael , Schmid Ulrich 
Published: April 2021

Abstract
In this paper a design concept and a finite element analysis of a combined electromagnetic/piezoelectric scalable hybrid energy harvesting device is presented, which converts mechanical energy from low frequency rotations into electrical energy. The electromagnetic (EM) transducer comprises an electric coil and a permanent magnet which is moved by the changing gravitation force vector caused by the rotational movement. The piezoelectric (PE) transducer is based on a vibrational energy harvester excited through magnetic plugging, which is induced by the movement of the permanent magnet of the EM harvester. As the magnetic plugging mechanism acts as a frequency-up conversion the device can be used in a wide range of rotational frequencies. The performance of both transducers is evaluated by finite element simulations to estimate the output power.
Influence of eccentric nanoindentation on top surface of silicon micropillar arrays
Authors: Puranto Prabowo , Zhang Qiang , Nyang’au Wilson O , Langfahl-Klabes Jannick , Thiesler Jan , Zackaria Mutaib , Li Zhi , Wasisto Hutomo S , Peiner Erwin , Brand Uwe 
Published: April 2021

Abstract
In this paper we present an investigation of the influence of nanoindentation location on the top surface of silicon micro-pillar. This silicon micro-pillar array which will be employed as a micro force sensor array based on three-dimension silicon (3D Si) structures, is fabricated by near UV nanoimprint lithography (NIL) technique and etched by Cryogenic Inductively Coupled Plasma (ICP) sequentially. To determine its mechanical properties, those micropillars are measured by instrument indentation testing (IIT) to obtain its hardness and reduced modulus. For the measurement, a Berkovich diamond indenter is utilized to penetrate a single and also multiple point indentations on a micro-pillar surface. Afterwards, these results are compared to the indentation at the central point of the tested pillar and Si bulk as its reference to examine the influence of different probing locations on the measured reduced modulus and hardness.
Electrical and Microstructural Characterization of TiO2 Thin Films for Flexoelectric Devices
Authors: Maier Franz Josef , Schneider Michael , Schrattenholzer Jürgen , Schmid Ulrich 
Published: April 2021

Abstract
This work investigates the flexoelectric potential of titanium oxide thin films regarding their microstructural and electrical properties to be integrated into nanoscaled resonators. Flexoelectricity is an electromechanical effect that can result in deformation of a material due to a polarization gradient and can outperform piezoelectric effects at the nanoscale. The flexoelectric constant is linearly dependent on the permittivity and therefore we determined TiO2 as a suitable flexoelectric material because of its high permittivity, its CMOS compatability and its linearity with respect to polarization. TiO2 capacitors with various electrode materials are evaluated in order to achieve the c-axis oriented (110) rutile growth, thus to exploit the highest permittivity. The permittivity ranges from 65 to 95, with TiO2 on IrO2 electrodes representing the highest value achieved in this study. As expected, the IrO2/TiO2/IrO2 capacitors show an almost constant impedance up to 200 kHz and have leakage current density values of ∼10−3 A/cm2 at 0.5 MV/cm at room temperature.
Force/Displacement MEMS Based on Electromagnetic Field Principle for Tiny Insects Monitoring
Authors: Hricko Jaroslav , Hartansky Rene , Andok Robert , Nemec Pavol , Tsai Hung-Yin 
Published: April 2021

Abstract
The novel electromagnetic field principle of a wireless measurement of the small displacement (forces) enables its utilization in a wide range of applications. This paper describes the design and fabrication of the physical model of a one-axis force sensor, but together shows possible applications of the proposed wireless electromagnetic field principle for the compact compliant mechanisms or for tiny insects monitoring.
Modeling the self-penetration process of a bio-inspired probe in granular soils
Authors: Chen Yuyan , Khosravi Ali , Martinez Alejandro , DeJong Jason 
Published: April 2021

Abstract
Soil penetration is an energy-intensive process that is common in both nature and civil infrastructure applications. Many human construction activities involve soil penetration that is typically accomplished through impact-driving, pushing against a reaction mass, excavating, or vibrating using large equipment. This paper presents a numerical investigation into the self-penetration process of a probe that uses an ‘anchor–tip’ burrowing strategy with the goal of extending the mechanics-based understanding of burrower–soil interactions at the physical dimensions and stress levels relevant for civil infrastructure applications. Self-penetration is defined here as the ability of a probe to generate enough anchorage forces to overcome the soil penetration resistance and advance the probe tip to greater depths. 3D Discrete element modeling simulations are employed to understand the self-penetration process of an idealized probe in noncohesive soil along with the interactions between the probe’s anchor and tip. The results indicate that self-penetration conditions improve with simulated soil depth, and favorable probe configurations for self-penetration include shorter anchor–tip distances, anchors with greater length and expansion magnitudes, and anchors with a greater friction coefficient. The results shed light on the scaling of burrowing forces across a range of soil depths relevant to civil infrastructure applications and provide design guidance for future self-penetrating probes.
Quantized dynamics in closed quantum systems
Authors: Ziegler K 
Published: April 2021

Abstract
We propose an approach to process data from interferometric measurements on a closed quantum system at random times. For this purpose a time correlation matrix is introduced which enables us to extract dynamical properties of the quantum system. After defining a generalized expectation value we obtain a distribution of time scales, an average transition time and a correlation time. A classical limit exists which is separated from the quantum fluctuations. The latter are characterized by resonances associated with poles of the generalized expectation value. Its analytic behavior is studied and some generic properties are linked to a quantized Berry phase.
Colorimetric quantification of aqueous hydrogen peroxide in the DC plasma-liquid system
Authors: YU Renze , LIU Zhaoyuan , LIN Jiao , HE Xinyi , LIU Linsheng , XIONG Qing , CHEN Qiang , OSTRIKOV Kostya (Ken) 
Published: April 2021

Abstract
The quantification of hydrogen peroxide (H2O2) generated in the plasma-liquid interactions is of great importance, since the H2O2 species is vital for the applications of the plasma-liquid system. Herein, we report on in situ quantification of the aqueous H2O2 (H2O2aq) using a colorimetric method for the DC plasma-liquid systems with liquid as either a cathode or an anode. The results show that the H2O2aq yield is 8–12 times larger when the liquid acts as a cathode than when the liquid acts as an anode. The conversion rate of the gaseous OH radicals to H2O2aq is 4–6 times greater in the former case. However, the concentrations of dissolved OH radicals for both liquid as cathode and anode are of the same order of tens of nM.
Quantum random access memory via quantum walk
Authors: Asaka Ryo , Sakai Kazumitsu , Yahagi Ryoko 
Published: April 2021

Abstract
A novel concept of quantum random access memory (qRAM) employing a quantum walk is provided. Our qRAM relies on a bucket brigade scheme to access the memory cells. Introducing a bucket with chirality left and right as a quantum walker, and considering its quantum motion on a full binary tree, we can efficiently deliver the bucket to the designated memory cells, and fill the bucket with the desired information in the form of quantum superposition states. Our procedure has several advantages. First, we do not need to place any quantum devices at the nodes of the binary tree, and hence in our qRAM architecture, the cost to maintain the coherence can be significantly reduced. Second, our scheme is fully parallelized. Consequently, only O(n) steps are required to access and retrieve O(2
n
) data in the form of quantum superposition states. Finally, the simplicity of our procedure may allow the design of qRAM with simpler structures.
Reference frame independent twin field quantum key distribution with source flaws
Authors: Sekga Comfort , Mafu Mhlambululi 
Published: April 2021

Abstract
The trade-off between distance and secret key generation rate remains one of the major challenges in the practical implementation of quantum key distribution (QKD). As a solution, a twin field QKD protocol was proposed by Lucamarini et al (2018) to address this challenge. In this protocol, the achievable secret key rate scales with the square root of channel transmittance and can surpass the secret key capacity for repeaterless QKD. However, the protocol exploits phase to encode information which presents the problem of active stabilization of interferometers. We propose a reference frame independent twin field quantum key distribution (RFITF QKD), which does not require the reference frames’ alignment. Thus, this reduces the complexity of practical QKD systems in achieving active stabilization of phase. Moreover, we employ the loss-tolerant method proposed by Tamaki et al (2014) which allows us to prove the security of the protocol by considering imperfections in the state preparation. Our simulation results show that our proposed protocol can extract a secure key over a transmission distance of l = 505 km, l = 516 km and l = 530 km for deviation of 8.42°, 7.28° and 5.15°, respectively from the desired phase encoding angle. These results demonstrate that despite the state preparation flaws, the key rates achieved are still comparable to the perfect encoding scenario. When our proposed protocol is implemented with an imperfect source, it achieves a transmission distance beyond the secret key capacity bound for repeaterless QKD.
Genetic divergence, admixture and subspecific boundaries in a peripheral population of the great tit, Parus major (Aves: Paridae)
Authors: Javaheri Tehrani Sahar , Kvist Laura , Mirshamsi Omid , Ghasempouri Seyed Mahmoud , Aliabadian Mansour 
Published: April 2021

Abstract
Secondary contact zones have been formed between several pairs of avian species and subspecies in northern and north-eastern Iran during the post-Pleistocene and Holocene periods. Three subspecies groups out of the four in the great tit (Parus major), major, bokharensis and cinereus, are believed to have come into local or regional secondary contact in north-eastern Iran. Parus major intermedius is also known from this region and has long been suggested to have a hybrid origin from hybridization between the yellow western (major) subspecies group and the grey-coloured eastern (bokharensis or cinereus) subspecies group based on its intermediate plumage coloration. Here, we investigated the evidence of intergradation between subspecies groups and the evolutionary origin of P. m. intermedius using mitochondrial DNA sequences and microsatellites, and approximate Bayesian computation to test competing scenarios for the demographic history of the populations. Our analyses indicate a divergence origin for intermedius that resulted from expansion of the major subspecies group. Low mitochondrial diversity and high genetic differentiation in comparison with central populations suggest that intermedius is a peripheral population. Microsatellite data show no signs of nuclear admixture between the bokharensis and major subspecies groups. However, one phenotypically intermedius specimen had bokharensis mtDNA and major nuclear DNA in the assumed hybrid zone (Lotf Abad), supporting past introgression.
Overcoming Penal Boundaries: Exploring The Evolution of Retributive Time Through Parole Decision-Making
Authors: Dagan Netanel 
Published: April 2021

AbstractThe relations between sentencing and post-sentencing stages (e.g., the implementation of prison, parole or community-based sanctions) are often perceived through temporal, spatial and normative binaries. The static time of retributive calibration—as fully known at sentencing time—stands at the heart of this separation. Through qualitative findings drawn from parole-board chairpersons in Israel, the paper argues that retributive punishment may evolve with time. As the findings suggest, parole decision-makers often go beyond risk and rehabilitation and reframe, reinterpret and renegotiate the dimensions of the deserved punishment. Three temporally dynamic themes of retributive discourses were described: (1) unexpected suffering review; (2) moral character revaluation; and (3) diminished censure reassessment. The findings challenge both the static conceptualization of retributive time and the instrumental view of parole decision-making. More generally, the findings question the assumed strict boundaries between sentencing and post-sentencing stages and call for future scholarly engagement with the evolution of punishment over time.
How Power Dynamics and Relationships Interact with Assessment of Competence: Exploring the Experiences of Student Social Workers Who Failed a Practice Placement
Authors: Roulston Audrey , Cleak Helen , Nelson Robby , Hayes David 
Published: April 2021

Abstract
Students have identified practice placements (or practice learning) as the single most important factor of social work education, but it is usually where issues of professional suitability become apparent. Whilst most students successfully complete their placements, a number experience difficulty and a minority ultimately fail. Protecting the profession from students not deemed suitable for professional practice requires a rigorous gatekeeping function and fair standards. On receipt of written consent, we interviewed eleven social work students who failed placement, and accessed progress reports written by Practice Teachers/Practice Educators. Participants included nine females, mean age of 33 years, seven failed their final placement and eight had registered with university disability services. Professionally transcribed interviews were analysed using an adapted version of Braun and Clarke’s method. Identified themes included the impact of personal issues; importance of working relationships; use and misuse of power; assessment and decision-making processes and developing insight and useful feedback. Students valued the opportunity to reflect on their experience and provided clear recommendations for improving how Practice Teachers, on-site supervisors, Tutors and peers can provide a supportive learning experience for students who require additional support during placement, and how to communicate concerns regarding competence more effectively.