bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear/nonlinear optical parameters along with photon attenuation effectiveness of Dy3+ ions doped zinc-aluminoborosilicate glasses
Authors: Tekin H O , Alomairy Sultan , Al-Buriahi M S , Rammah Y S
Published: April 2021

In this study linear/nonlinear optical and γ-photon attenuation competences of dysprosium oxide (Dy3+ ions) doped zinc-aluminoborosilicate glasses based on (40−x) B2O3—20SiO2 –10Al2O3 –20NaF—10ZnO—xDy2O3, (where x = 0, 0.1, 0.5, 1.0. 1.5, 2.0 and 2.5 mol%) were investigated. Different types of calculation methods along with Monte Carlo simulations were used for determination of linear/nonlinear optical and γ-photon attenuation competences. Both molar refractivity (Rmolar) and molar polarizability (α
molar) decreased as Dy3+ ions concentration increased. The optical transmission (Toptical) of the investigated glasses varied inversely to their reflection loss (Rloss). The obtained values of metallization criterion (Mcriterion) quantity showed that the studied glasses are insulator materials. The results also showed that Dy2.5 sample with the highest amount of Dy2O3 additive has the highest mass attenuation coefficients (μ
m) and effective atomic number (Zeff) values. On the other hand, Half (HVL) and tenth (TVL) value layers were reported as (HVL, TVL)Dy0.0 > (HVL, TVL)Dy0.1 > (HVL, TVL)Dy0.5 > (HVL, TVL)Dy1.0 > (HVL, TVL)Dy1.5 (HVL, TVL)Dy2.0 > (HVL, TVL)Dy2.5. The maximum and minimum values of exposure and energy absorption buildup factors (EBF and EABF) were reported for Dy0.0 and Dy2.5 samples, respectively. It can be concluded that studied glasses are candidate materials for optical fibers and photonic devices. It can be also concluded that Dy2.5 sample is the superior sample in terms of gamma-ray attenuation competences.
A classical, non-singular, bouncing universe
Authors: Güngör Özenç , Starkman Glenn D.
Published: April 2021

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The 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

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.
Eco-Friendly Pharmaceutical Analysis of Rifaximin in Tablets by HPLC-MS and Microbiological Turbidimetry
Authors: Kogawa Ana Carolina , Mendonça Jacqueline Nakau , Lopes Norberto Peporine , Salgado Hérida Regina Nunes
Published: April 2021

Rifaximin, an antimicrobial used for the treatment of various diseases, lacks analytical methods in official compendia for evaluation of the final product. This paper presents an eco-friendly protocol for rifaximin tablets by high performance liquid chromatography coupled with mass spectrometry (HPLC-MS). The method was completely validated according to the International Conference on Harmonization guidelines and developed following the concept of Quality by Design. The separation was achieved using a C18 column, purified water +0.1% glacial acetic acid and ethyl alcohol, 52:48 (v/v), as mobile phase, 0.9 mL min−1 at 290 nm and ambient room temperature. Mass spectral analyses were performed using electrospray ionization (ESI) ion source and ion trap mass analyzer. The method was linear over the concentration range of 5–50 μg mL−1. The sample was subjected to acidic, basic, neutral, oxidative and photolytic degradation. Degradation products did not interfere in the quantification of the rifaximin, so the method can be considered indicative of stability. Degradation products were also evaluated individually by microbiological method using Escherichia coli. The validated method could be used promisingly as green analytical strategies for detection and quantification of rifaximin in tablets.
High Infection Secondary Attack Rates of Severe Acute Respiratory Syndrome Coronavirus 2 in Dutch Households Revealed by Dense Sampling
Authors: Reukers Daphne F M , van Boven Michiel , Meijer Adam , Rots Nynke , Reusken Chantal , Roof Inge , van Gageldonk-Lafeber Arianne B , van der Hoek Wim , van den Hof Susan
Published: April 2021

Background

Indoor environments are considered one of the main settings for transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Households in particular represent a close-contact environment with high probability of transmission between persons of different ages and roles in society.

Methods

Households with a laboratory-confirmed SARS-CoV-2 positive case in the Netherlands (March-May 2020) were included. At least 3 home visits were performed during 4-6 weeks of follow-up, collecting naso- and oropharyngeal swabs, oral fluid, feces and blood samples from all household members for molecular and serological analyses. Symptoms were recorded from 2 weeks before the first visit through to the final visit. Infection secondary attack rates (SAR) were estimated with logistic regression. A transmission model was used to assess household transmission routes.

Results

A total of 55 households with 187 household contacts were included. In 17 households no transmission took place; in 11 households all persons were infected. Estimated infection SARs were high, ranging from 35% (95% confidence interval [CI], 24%-46%) in children to 51% (95% CI, 39%-63%) in adults. Estimated transmission rates in the household were high, with reduced susceptibility of children compared with adolescents and adults (0.67; 95% CI, .40-1.1).

Conclusion

Estimated infection SARs were higher than reported in earlier household studies, presumably owing to our dense sampling protocol. Children were shown to be less susceptible than adults, but the estimated infection SAR in children was still high. Our results reinforce the role of households as one of the main multipliers of SARS-CoV-2 infection in the population.
A Virtual Network Embedding Algorithm Based On Double-Layer Reinforcement Learning
Authors: Li Meng , Lu MeiLian
Published: April 2021

Virtual network embedding (VNE) algorithms dominate the effectiveness of resource sharing in network virtualization. Heuristic embedding algorithms generally make embedding decisions by artificially specified strategies, in which the node importance is measured by simply summing or multiplying several node attributes. However, the contributions of different attributes may be combined through complex functional relationships. The reinforcement learning-based VNE algorithms can optimize node embedding. However, the existing algorithms only consider the local node attributes, and only simple shortest path-based embedding policy is adopted for link embedding, resulting limited embedding effects. To overcome the above defects, we propose a double-layer reinforcement learning-based VNE algorithm (DRL-VNE). In DRL-VNE, both the global and local node attributes are extracted to represent the status of network nodes, then a policy network is constructed to optimize node embedding, and the other policy network is designed to optimize link embedding. The performance of DRL-VNE is evaluated under different network scenarios and is compared with that of heuristic and machine learning-based VNE algorithms. Simulation results show that in hierarchical network scenario, the request acceptance ratio and the resource utilization of DRL-VNE are respectively improved by 14% and by 27% compared with the best performance comparison algorithm.
Austropuccinia psidii, causing myrtle rust, has a gigabase-sized genome shaped by transposable elements
Authors: Tobias Peri A , Schwessinger Benjamin , Deng Cecilia H , Wu Chen , Dong Chongmei , Sperschneider Jana , Jones Ashley , Luo Zhenyan , Zhang Peng , Sandhu Karanjeet , Smith Grant R , Tibbits Josquin , Chagné David , Park Robert F
Published: April 2021

Austropuccinia psidii, originating in South America, is a globally invasive fungal plant pathogen that causes rust disease on Myrtaceae. Several biotypes are recognized, with the most widely distributed pandemic biotype spreading throughout the Asia-Pacific and Oceania regions over the last decade. Austropuccinia psidii has a broad host range with more than 480 myrtaceous species. Since first detected in Australia in 2010, the pathogen has caused the near extinction of at least three species and negatively affected commercial production of several Myrtaceae. To enable molecular and evolutionary studies into A. psidii pathogenicity, we assembled a highly contiguous genome for the pandemic biotype. With an estimated haploid genome size of just over 1 Gb (gigabases), it is the largest assembled fungal genome to date. The genome has undergone massive expansion via distinct transposable element (TE) bursts. Over 90% of the genome is covered by TEs predominantly belonging to the Gypsy superfamily. These TE bursts have likely been followed by deamination events of methylated cytosines to silence the repetitive elements. This in turn led to the depletion of CpG sites in TEs and a very low overall GC content of 33.8%. Compared to other Pucciniales, the intergenic distances are increased by an order of magnitude indicating a general insertion of TEs between genes. Overall, we show how TEs shaped the genome evolution of A. psidii and provide a greatly needed resource for strategic approaches to combat disease spread.
A mixed-methods study of American Millennials’ views about celebrity endorsement of foods and beverages
Authors: Zhou Mi , Kraak Vivica
Published: April 2021

More than one-third of American Millennial adults have obesity, and a significant amount of their household budget is spent on purchasing energy-dense and nutrient-poor food and beverage products. Consumers’ brand awareness and purchasing behaviors are influenced by celebrity credibility measured by trustworthiness, expertise and attractiveness; and celebrity ‘fit’ between products, brands and consumer’ self-image. This empirical mixed-methods study combined Q methodology with questionnaires to explore the shared and distinct viewpoints of demographically diverse Millennial adults about celebrity endorsement of food and beverage products or marketing campaigns in the United States (USA). Millennials (n = 40; aged 26–39 years) sorted photo images (n = 48) of US celebrities associated with branded food and beverage product endorsements on a 9-point normal distribution scale from ‘most trusted’ (+4) to ‘most distrusted’ (−4). Participants also completed a 4-item post Q-sort questionnaire to interpret their thoughts during the card sorting process, and a 3-item questionnaire to examine their views about celebrity credibility, ‘fit’ and multiple brand and product endorsements. Three distinct viewpoints were identified that included: (i) healthy lifestyle champions who trusted celebrities associated with healthy products or campaigns; (ii) female role-model admirers who trusted female celebrities associated with positive social impacts and (ii) African-American celebrity fans who trusted African-American celebrities who endorsed any brand or products. Qualitative analysis of the questionnaire identified the potential negative influence of celebrity endorsement for unhealthy products on Millennials’ dietary behaviors. Businesses and organizations should carefully select credible celebrities trusted by Millennials to encourage food and beverage products associated with a healthy diet.
Reflection on modern methods: shared-parameter models for longitudinal studies with missing data
Authors: Griswold Michael E , Talluri Rajesh , Zhu Xiaoqian , Su Dan , Tingle Jonathan , Gottesman Rebecca F , Deal Jennifer , Rawlings Andreea M , Mosley Thomas H , Windham B Gwen , Bandeen-Roche Karen
Published: April 2021

A primary goal of longitudinal studies is to examine trends over time. Reported results from these studies often depend on strong, unverifiable assumptions about the missing data. Whereas the risk of substantial bias from missing data is widely known, analyses exploring missing-data influences are commonly done either ad hoc or not at all. This article outlines one of the three primary recognized approaches for examining missing-data effects that could be more widely used, i.e. the shared-parameter model (SPM), and explains its purpose, use, limitations and extensions. We additionally provide synthetic data and reproducible research code for running SPMs in SAS, Stata and R programming languages to facilitate their use in practice and for teaching purposes in epidemiology, biostatistics, data science and related fields. Our goals are to increase understanding and use of these methods by providing introductions to the concepts and access to helpful tools.
The maximum likelihood ensemble filter for computational flame and fluid dynamics
Authors: Wang Yijun , Guzik Stephen , Zupanski Milija , Gao Xinfeng
Published: April 2021

The numerical solution of partial differential equations that govern fluid dynamics with turbulence and combustion is challenging due to the multiscale nature of the dynamical system and the need to resolve small-scale physical features. In addition, the uncertainties in the dynamical system, including those in the physical models and parameters, initial and boundary conditions and numerical methods, impact the computational fluid dynamics (CFD) prediction of turbulence and chemical reactions. To improve the CFD prediction, this study focuses on the development and application of a maximum likelihood ensemble filter (MLEF), an ensemble-based data assimilation (DA), for flows featuring combustion and/or turbulence. MLEF finds the optimal analysis and its uncertainty by maximizing the posterior probability density function. The novelty of the study lies in the combination of advanced DA and CFD methods for a new comprehensive application to predict engineering fluid dynamics. The study combines important aspects, including an ensemble-based DA with analysis and uncertainty estimation, an augmented control vector that simultaneously adjusts initial conditions and model empirical parameters and an application of DA to CFD modeling of combustion and flows with complex geometry. The DA performance is validated by a turbulent Couette flow. The new CFD–DA system is then applied to solve the time-evolving shear-layer mixing with methane-air combustion and the turbulent flow over a bluff-body geometry. Results demonstrate the improvement of estimates of model parameters and the uncertainty reduction in initial conditions (ICs) for CFD modeling of flames and flows by the MLEF method.
A dual self-monitored reconstruction scheme on theTV-regularized inverse conductivity problem
Authors: Markaki Vanessa , Kourounis Drosos , Charalambopoulos Antonios
Published: April 2021

Recently in Charalambopoulos et al. (2020), we presented a methodology aiming at reconstructing bounded total variation ($TV$) conductivities via a technique simulating the so-called half-quadratic minimization approach, encountered in Aubert & Kornprobst (2002, Mathematical Problems in Image Processing. New York, NY: Springer). The method belongs to a duality framework, in which the auxiliary function $\omega (x)$ was introduced, offering a tool for smoothing the members of the admissible set of conductivity profiles. The dual variable $\omega (x)$, in that approach, after every external update, served in the formation of an intermediate optimization scheme, concerning exclusively the sought conductivity $\alpha (x)$. In this work, we develop a novel investigation stemming from the previous approach, having though two different fundamental components. First, we do not detour herein the $BV$-assumption on the conductivity profile, which means that the functional under optimization contains the $TV$ of $\alpha (x)$ itself. Secondly, the auxiliary dual variable $\omega (x)$ and the conductivity $\alpha (x)$ acquire an equivalent role and concurrently, a parallel pacing in the minimization process. A common characteristic between these two approaches is that the function $\omega (x)$ is an indicator of the conductivity’s ‘jump’ set. A fortiori, this crucial property has been ameliorated herein, since the reciprocal role of the elements of the pair $(\alpha ,\omega )$ offers a self-monitoring structure very efficient to the minimization descent.
Cell culture selections reveal favourable drug resistance profiles for doravirine and islatravir
Authors: Brenner Bluma G , Oliveira Maureen , Ibanescu Ruxandra-Ilinca , Routy Jean-Pierre , Thomas Réjean
Published: April 2021

Background

The newer generation NNRTIs, including doravirine and rilpivirine, were designed to show high potency and overcome K103N, Y181C and G190A resistance.

Objectives

To assess emergent resistance to doravirine and rilpivirine, alone and paired with lamivudine or islatravir through in vitro drug selections.

Methods

Subtype B (n = 3), non-B subtype (n = 3), and pNL4.3 viral isolates were passaged in cord blood mononuclear cells with progressively increasing concentrations of drug(s). Genotypic analysis compared the acquisition and accumulation of drug resistance mutations at weeks 8 and 24 following drug pressure. Cell-based phenotypic assays assessed cross-resistance patterns to NNRTIs by acquired resistance mutations.

Results

Doravirine pressure resulted in the acquisition of V108I (6/7) and V106A/I/M (5/7) mutations at weeks 8, followed by F227L (4/7), Y318F (4/7), M230L (2/7) or L234I (2/7) by weeks 24. In contrast, rilpivirine resulted in E138K (5/7) followed by L100I (3/7), K101E (1/7), or M230L (1/7). Doravirine resistance pathways retained susceptibility to rilpivirine, whereas rilpivirine resistance conferred intermediate resistance (12–152-fold) to doravirine. Dual selections with islatravir or lamivudine delayed and diminished emergent resistance to doravirine, resulting in V108I (9/15) with fewer or no other changes at weeks 24. There was a lesser delay in emergent resistance to rilpivirine when combined with islatravir or lamivudine. The M184V mutation did not arise in dual selections with islatravir or lamivudine.

Conclusions

Doravirine showed a more robust resistance profile compared with other NNRTIs. The long intracellular half-life of islatravir and delayed acquisition of resistance in dual selections provide an opportunity for long-acting treatment options.
Stroke risk prediction using machine learning: a prospective cohort study of 0.5 million Chinese adults
Authors: Chun Matthew , Clarke Robert , Cairns Benjamin J , Clifton David , Bennett Derrick , Chen Yiping , Guo Yu , Pei Pei , Lv Jun , Yu Canqing , Yang Ling , Li Liming , Chen Zhengming , Zhu Tingting ,   the China Kadoorie Biobank Collaborative Group
Published: April 2021

Objective

To compare Cox models, machine learning (ML), and ensemble models combining both approaches, for prediction of stroke risk in a prospective study of Chinese adults.

Materials and Methods

We evaluated models for stroke risk at varying intervals of follow-up (<9 years, 0–3 years, 3–6 years, 6–9 years) in 503 842 adults without prior history of stroke recruited from 10 areas in China in 2004–2008. Inputs included sociodemographic factors, diet, medical history, physical activity, and physical measurements. We compared discrimination and calibration of Cox regression, logistic regression, support vector machines, random survival forests, gradient boosted trees (GBT), and multilayer perceptrons, benchmarking performance against the 2017 Framingham Stroke Risk Profile. We then developed an ensemble approach to identify individuals at high risk of stroke (>10% predicted 9-yr stroke risk) by selectively applying either a GBT or Cox model based on individual-level characteristics.

Results

For 9-yr stroke risk prediction, GBT provided the best discrimination (AUROC: 0.833 in men, 0.836 in women) and calibration, with consistent results in each interval of follow-up. The ensemble approach yielded incrementally higher accuracy (men: 76%, women: 80%), specificity (men: 76%, women: 81%), and positive predictive value (men: 26%, women: 24%) compared to any of the single-model approaches.

Discussion and Conclusion

Among several approaches, an ensemble model combining both GBT and Cox models achieved the best performance for identifying individuals at high risk of stroke in a contemporary study of Chinese adults. The results highlight the potential value of expanding the use of ML in clinical practice.
14 Use of Airway Pressure Relief Ventilation (APRV) in Burn Patients With and Without Inhalation Injury
Authors: Foster Kevin N , Buchanan Dylon , Durr Timothy , Richey Karen J
Published: April 2021

Introduction

Burn patients often require ventilator management because of large % TBSA injury, the presence of inhalation injury, and/or other factors. Airway pressure relief ventilation (APRV) offers several advantages over conventional ventilation modes including improved alveolar recruitment, better oxygenation and hemodynamics, preservation of spontaneous breathing, and possibly less ventilator-induced lung injury. This study reviews the use of APRV as the primary ventilator mode in burn patients with and without inhalation injury.

Methods

A retrospective chart review of patients admitted to the burn center and requiring APRV ventilation over a ten-year period was performed. Data collected included demographic data, burn injury data, ventilator settings, arterial blood gas data, and development of ventilator-associated pneumonia (VAP).

Results

There were 411 patients identified over the ten-year period. Mean age was 46 years, and mean % TBSA burned was 33. Seventy-three percent were male. One-half (51%) of patients had an inhalation injury. Mean hospital length of stay was 32 days with 22 mean ventilator days. Average number of surgeries was 4.4 per patient. Mean high pressure (P high) was 23 mm Hg. Mean FiO2 was 88% on post-injury day (PID) 1, 65% on day PID 2, and 45% thereafter. Mean P/F ratio was 333. Mean pH was 7.40, mean pCO2 was 40 mmHg, and mean HCO3 was 25 mm Hg. Forty-six percent of patients met criteria for diagnosis of VAP.

Conclusions

These data demonstrate that burn patients requiring mechanical ventilation can be safely and effectively managed with APRV. Oxygenation, carbon dioxide removal, normal acid-base status, and excellent P/F ratios were maintained with relatively low ventilator settings such as peak airway pressure and FiO2. Patients were able to breathe spontaneously when able and were easily liberated form the ventilator at the appropriate time.
19 Nebulized Tobramycin is Associated with Decreased Pneumonia After Inhalation Injury
Authors: Chin Theresa L , Frerk Rita , Joe Victor C , Bernal Nicole O
Published: April 2021

Introduction

Management of inhalation injury is largely supportive and consists primarily of mechanical ventilation, bronchodilators, muscarinic receptor antagonists, and inhaled mucolytics and anticoagulants. Patients with inhalation injury are at high risk for pneumonia. Nebulized tobramycin is well supported in the use of chronic lung infections in patients with cystic fibrosis (CF). We hypothesize that after inhalation injury patients empirically treated with nebulized tobramycin (NT) have decreased incidence of pneumonia.

Methods

A protocol for a standardized 7-day course of nebulized treatments with bronchodilators, inhaled mucolytics combined with inhaled anticoagulants and Nebulized tobramycin was developed. Starting in May 2013, all patients that had a clinical diagnosis of inhalation documented by the attending physician were started on the 7-day treatment course. Patients with inhalation injury from 2009–2019 were retrospectively reviewed for treatment of inhalation injury. Univariate analysis and multiple logistic regression were performed using Stata.

Results

Of 90 patients with inhalation injury, median age was 52 (IQR:31–60) with 27% (n=23) women and median TBSA of 10%(IQR:0.7–35%). The median length of stay was 21 days (IQR:6–47). Median ventilator days were lower in patients treated with NT (8.5, IQR:4–21) compared to patients that did not receive NT (10, IQR:3–23) but was not significant (p=0.85). However, of those that received NT, the presence of pneumonia was significantly lower compared to patients not treated with NT (p=0.032). (Table 1) Patients who were not treated with NT developed pneumonia earlier (day 5, IQR:3–7) than patients treated with NT (day 10, IQR 6–16, p=0.02) After adjusting for grade of inhalation injury, patients who did not receive NT were 2.7 times as likely to get pneumonia compared to patients who received NT (p=0.037).

Conclusions

NT is a prophylactic strategy for pneumonia in patients with CF, well documented to be safe. It allows for concentrated antibacterial coverage localized to the area of infection without significant systemic absorption. After seeing ~60% incidence of pneumonia in inhalation patients, we developed a strategy that avoided systemic prophylactic treatment. Initial data shows empiric administration of NT in patients with inhalation injury may abrogate the development pneumonia. Additional research and clinical trials are needed to better understand the role of inhaled tobramycin in the management of inhalation injury.