bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-term Impact of Adenotonsillectomy on the Quality of Life of Children with Sleep-disordered breathing
Authors: Caixeta Juliana Alves Sousa , Sampaio Jessica Caixeta Silva , Costa Vanessa Vaz , Silveira Isadora Milhomem Bruno da , Oliveira Carolina Ribeiro Fernandes de , Caixeta Luiz Claudio Alves Sousa , Avelino Melissa Ameloti Gomes
Published: May 2020

Introduction Adenotonsillectomy is the first-line treatment for obstructive sleep apnea secondary to adenotonsillar hypertrophy in children. The physical benefits of this surgery are well known as well as its impact on the quality of life (QoL), mainly according to short-term evaluations. However, the long-term effects of this surgery are still unclear.

Objective To evaluate the long-term impact of adenotonsillectomy on the QoL of children with sleep-disordered breathing (SDB).

Method This was a prospective non-controlled study. Children between 3 and 13 years of age with symptoms of SDB for whom adenotonsillectomy had been indicated were included. Children with comorbities were excluded. Quality of life was evaluated using the obstructive sleep apnea questionnaire (OSA-18), which was completed prior to, 10 days, 6 months, 12 months and, at least, 18 months after the procedure. For statistical analysis, p-values lower than 0.05 were defined as statistically significant.

Results A total of 31 patients were enrolled in the study. The average age was 5.2 years, and 16 patients were male. The OSA-18 scores improved after the procedure in all domains, and this result was maintained until the last evaluation, done 22 ± 3 months after the procedure. Improvement in each domain was not superior to achieved in other domains. No correlation was found between tonsil or adenoid size and OSA-18 scores.

Conclusion This is the largest prospective study that evaluated the long-term effects of the surgery on the QoL of children with SDB using the OSA-18. Our results show adenotonsillectomy has a positive impact in children's QoL.
Turbulent drag reduction in magnetohydrodynamic and quasi-static magnetohydrodynamic turbulence
Authors: Verma Mahendra K. , Alam Shadab , Chatterjee Soumyadeep
Published: May 2020

In hydrodynamic turbulence, the kinetic energy injected at large scales cascades to the inertial range, leading to a constant kinetic energy flux. In contrast, in magnetohydrodynamic (MHD) turbulence, a fraction of kinetic energy is transferred to the magnetic energy. Consequently, for the same kinetic energy injection rate, the kinetic energy flux in MHD turbulence is reduced compared to its hydrodynamic counterpart. This leads to relative weakening of the nonlinear term ⟨|(u·∇)u|⟩, (where u is the velocity field) and turbulent drag, but strengthening of the velocity field in MHD turbulence. We verify the above using shell model simulations of hydrodynamic and MHD turbulence. Quasi-static MHD turbulence too exhibits turbulent drag reduction similar to MHD turbulence.
Electron energy-loss spectroscopic evaluation of depth-dependent swelling of He+ ion-irradiated 4H-SiC correlated with defect type
Authors: Yang Subing , Nakagawa Yuki , Kondo Minako , Shibayama Tamaki
Published: May 2020

Various defects and amorphous transitions are the primary mechanism behind the accumulation of swelling in silicon carbide (SiC). In this study, selected-area He+ ion irradiation was carried out on single-crystal 4H-SiC using fluences of 1 × 1015, 5 × 1016, and 1 × 1017 cm−2 at room temperature. The defect distribution in the samples with varying irradiation fluences was analyzed using transmission electron microscopy (TEM), while the local swelling of regions under varying damage conditions was estimated using electron energy-loss spectroscopy. The results provide the range of swelling in SiC possessing different primary defect types, such as point defects or tiny clusters, black spot defects, and amorphous SiC. A saturation swelling with a value of 2%–3% in the near-surface region, induced by point defects or tiny clusters (invisible in TEM), was observed at room temperature over the fluence range of 1 × 1015 to 1 × 1017 cm−2. This saturation has already reached at a great low dose of about 0.02 dpa. The swelling of the region containing black spot defects ranges from about 3% to 7%. Helium bubbles increase the volume swelling of SiC, while the He+ ion irradiation may also perform a decreasing effect on the volume swelling below a certain irradiation fluence.
Charge transport in metal–organic frameworks for electronics applications
Authors: Calvo James J. , Angel Sydney M. , So Monica C.
Published: May 2020

In recent years, functional electronic nanomaterials have made significant strides from advancements in the interplay of physics, chemistry, materials science, and computational research. However, synthetically tunable electronic materials are a long-standing, but elusive, technological goal. More recently, metal–organic frameworks (MOFs), a class of nanoporous, hybrid inorganic–organic crystalline solids, have garnered attention as a novel class of electronic nanomaterials. The aim of this perspective is to (i) highlight the charge transport behavior of recently discovered (2017–2019) electronic MOFs and (ii) recommend future directions for improvement of intrinsically and extrinsically conductive MOFs for MOF-based electronics.
Numerical method for lightning transient analysis of photovoltaic bracket systems
Authors: Wang Yaowu , Zhang Xiaoqing , Tao Shiqi
Published: May 2020

A calculating method is proposed for lightning transient analysis in photovoltaic bracket systems. The circuit parameters are evaluated for the conducting branches and grounding electrodes. On the ground of the circuit parameters, the equivalent circuit model is set up for photovoltaic bracket systems. The transient calculation is made by the circuit model and the potential and current responses are obtained in photovoltaic bracket systems. The laboratory-experiment is performed on a reduced-scale photovoltaic bracket system. The results obtained from the measurement are compared with those from the transient calculation to confirm the validity of the circuit model. Then, the probability density function of lightning current is further introduced into the statistical analysis of lightning transients. By means of the transient calculations made in a large interval of lightning current amplitudes, the statistical values of the nodal potential and branch current amplitudes are calculated by probability weights. A numerical example is also given for examining the difference between the statistical and non-statistical values. The proposed method can take account of the actual randomness of lightning discharge and afford a sound basis for lightning protection design of photovoltaic bracket systems.
2D simulation of a copper cathode spot jet considering the charge composition in vacuum arc
Authors: Sun Qiang , Yang Wei , Zhou Qianhong
Published: May 2020

Plasma in the vacuum arc is usually generated by numerous cathode spots on the cathode surface, each of which produces a supersonic plasma jet. This work studies the physical mechanisms of supersonic ion flow in a cathode spot jet of vacuum arc by using a two-dimension magneto-hydro-dynamic numerical model that considers ionization and recombination processes. Simulation results are presented for different currents of the copper cathode spot (I = 3, 4, and 5 A). The results indicate that in the cathode spot region, there are huge electron and ion pressure gradients (1013–1014 Pa/m) in both axial and radial directions, resulting in the rapid expansion of the plasma jet in all directions. The expansion of the plasma jet decreases the ion density rapidly from 1026 m−3 to 1022 m−3, and the ions reach supersonic speed within 0.4 μm from the cathode spot. Moreover, within 0.2 μm from the cathode spot, vaporized copper atoms quickly become completely ionized because of high electron temperature and electron density. Beyond a certain distance from the cathode spot, the recombination and ionization rates of the ions will be insufficient to alter the ion charge state. In most of the region, the average charge state varies from 1.84 to 2.05. Finally, the plasma parameters of the cathode spot jet predicted by the proposed numerical model are consistent with the experimental and theoretical results.
Time-resolved ultrafast transient polarization spectroscopy to investigate nonlinear processes and dynamics in electronically excited molecules on the femtosecond time scale
Authors: Thurston Richard , Brister Matthew M. , Belkacem Ali , Weber Thorsten , Shivaram Niranjan , Slaughter Daniel S.
Published: May 2020

We report a novel experimental technique to investigate ultrafast dynamics in photoexcited molecules by probing the 3rd-order nonlinear optical susceptibility. A non-collinear 3-pulse scheme is developed to probe the ultrafast dynamics of excited electronic states using the optical Kerr effect. Optical homodyne and optical heterodyne detections are demonstrated to measure the 3rd-order nonlinear optical response for the S1 excited state of liquid nitrobenzene, which is populated by 2-photon absorption of a 780 nm 40 fs excitation pulse.
Demonstration of efficient beam-wave interaction for a MW-level 48 GHz gyroklystron amplifier
Authors: Nix L. J. R. , Zhang L. , He W. , Donaldson C. R. , Ronald K. , Cross A. W. , Whyte C. G.
Published: May 2020

The development of high-frequency RF linear accelerators (linacs) requires the consideration of several technological challenges, such as electron bunch linearization. Presented in this paper is the design of the interaction circuit for a 48 GHz MW-level three-cavity gyroklystron amplifier, appropriate for application as a millimeter wave power source in a fourth harmonic linearizing system for an X-band linac. The output cavity is operated at the cylindrical TE0,2,1 mode, while the input and buncher cavities are operated at the TE0,1,1 mode. The interaction circuit has been designed using a combination of analytical calculations and particle-in-cell simulations. The optimized gyroklystron is shown, through simulation, to deliver an output power of up to 2.3 MW with a gain of 36 dB and an efficiency of 44% at 48 GHz, when driven by a 140 kV, 37 A electron beam.
Updates to water’s equation of state hold the key to describing its anomalous behaviors
Authors: Bandari Anashe
Published: May 2020

Water’s anomalies are crucial for many organisms’ survival, but their origin has long been a topic of research.
Molybdenum lowers negative thermal expansion of zirconium vanadate to room temperature
Authors: Liebendorfer Adam
Published: May 2020

Partial substitution of molybdenum for vanadium atoms allows phenomenon of thermal contraction in zirconium vanadate at temperatures below ambient temperature.
A multi-functional cloaking technology with enhanced transmission in the giga-Hz regime
Authors: Chen Peiqi , Nie Qiuyue , Zhang Zhonglin , Li Bowen , Lin Shu , Qu Binnan
Published: May 2020

In the giga-Hz (GHz) regime, not only does an advanced electromagnetic platform need a stealth function to shield itself from radar detection, similar to the “invisible” cloak in the visible light regime, but also an enhanced transmission function to communicate with others. To satisfy the seemingly contradictory requirements, we here propose a multi-functional mode of plasma cloaking, invisible to radar detection but signal-enhanced in communication bands. Such a synergistic effect is achieved by combining a “detour” layer of cloaking and an enhancement layer of communication. Thus, with such a design we can successfully apply an ideal “cloak” to the low frequency detecting regime (in the P-band) and improve signal transmission capabilities in a higher frequency communication regime (in the L-band) at the same time. Furthermore, the tunability and limitations of the multi-functional system are discussed, and the principles of designing inner and outer plasma layers are acquired.
Acceleration scheme for particle transport in kinetic Monte Carlo methods
Authors: Kaiser Waldemar , Gößwein Manuel , Gagliardi Alessio
Published: May 2020

Kinetic Monte Carlo (kMC) simulations are frequently used to study (electro-)chemical processes within science and engineering. kMC methods provide insight into the interplay of stochastic processes and can link atomistic material properties with macroscopic characteristics. Significant problems concerning the computational demand arise if processes with large time disparities are competing. Acceleration algorithms are required to make slow processes accessible. Especially, the accelerated superbasin kMC (AS-kMC) scheme has been frequently applied within chemical reaction networks. For larger systems, the computational overhead of the AS-kMC is significant as the computation of the superbasins is done during runtime and comes with the need for large databases. Here, we propose a novel acceleration scheme for diffusion and transport processes within kMC simulations. Critical superbasins are detected during the system initialization. Scaling factors for the critical rates within the superbasins, as well as a lower bound for the number of sightings, are derived. Our algorithm exceeds the AS-kMC in the required simulation time, which we demonstrate with a 1D-chain example. In addition, we apply the acceleration scheme to study the time-of-flight (TOF) of charge carriers within organic semiconductors. In this material class, time disparities arise due to a significant spread of transition rates. The acceleration scheme allows a significant acceleration up to a factor of 65 while keeping the error of the TOF values negligible. The computational overhead is negligible, as all superbasins only need to be computed once.
Photonic integrated multiwavelength laser arrays: Recent progress and perspectives
Authors: Lee San-Liang , Lu Tien-Chang , Hung Yung-Jr , Chen Lih-Ren , Huang Zhen-Ting
Published: May 2020

With the significant technology advancement in photonic integration and the demands of compact light sources of multiple wavelengths, multiwavelength laser arrays (MWLAs) can play important roles in high-capacity optical signal transmission, photonic switching, and optical sensing. Manufacturing with semiconductor foundries and the integration with electronic integrated circuits bring not only advanced technologies but also new concepts for realizing MWLAs. This paper will first overview the existing technology development and then discuss the challenges and possible solutions for enabling photonic-integrated MWLAs. The overview will cover monolithically and hybrid-integrated MWLAs. The wavelength registration for both in-plane and vertical-cavity MWLAs will be discussed and compared.
Expansion dynamics and compression layer in collinear double-pulse laser produced plasmas in a vacuum
Authors: Cao Shiquan , Su Maogen , Liu Jinzhu , Min Qi , Sun Duixiong , He Siqi , Ma Pengpeng , Wang Kaiping , Dong Chenzhong
Published: May 2020

Collinear double-pulse (DP) laser-produced plasmas (LPP) of Al in a vacuum under a nanosecond–picosecond configuration were investigated. Combining fast imaging and laser interferometry, expansion profiles and electron density distributions of single pulse (SP) and nanosecond–picosecond collinear DP-LPP with inter-pulse time intervals of 20, 30, and 50 ns were obtained and their evolution characteristics were analyzed. A compression layer was observed during plasma expansion; both its shape and density distribution were controllable by varying the inter-pulse time interval. A special crescent-shaped compression layer was obtained, indicating that a special state of plasma had been prepared by collinear DP-LPP. The results of this study are helpful to a further understanding of expansion and evolution characteristics of collinear DP-LPP and provide an experimental basis for the development of a related theoretical model.
Extreme measurements with Photonic Doppler Velocimetry (PDV)
Authors: Dolan D. H.
Published: May 2020

Photonic Doppler Velocimetry (PDV) is a fiber-based diagnostic for the extreme conditions created by high-speed impact, explosive detonation, electrical pulsed power, and intense laser ablation. PDV is a conceptually simple application of the optical Doppler effect, but measurements above 1 km/s only became practical at the beginning of the twenty-first century. This review discusses the evolution of PDV, its operational details, practical analysis, and outstanding challenges.
Discrete-vortex analysis of high Reynolds number flow past a rotating cylinder
Authors: Chen Wei , Rheem Chang-Kyu , Zheng Yuanzhou , Incecik Atilla , Lin Yongshui , Li Zhixiong
Published: May 2020

Flow past a rotating cylinder is investigated using a two-dimensional discrete vortex simulation method in this study. The simplified Navier–Stokes equation is solved based on the relationship between the surface pressure gradient and the generated surface vortex strength. The Reynolds number based on the cylinder diameter and flow velocity is 105. The non-dimensional rotation rate, α (the ratio of the cylinder surface velocity and flow velocity), is varied between 0 and 19, and four different wake formations (vortex shedding, weak vortex shedding, wake, and rotating wake formations) have been derived by the imposed rotation. The relationship between the hydrodynamics and wake formation is illustrated. Under vortex shedding and weak vortex shedding formations, periodical hydrodynamics is induced. Under wake formation, no gap between the positive-vorticity and negative-vorticity layers results in the steady hydrodynamics. The separation of the rotating wake induces the huge fluctuation of hydrodynamics under rotating wake formation. These are significant for a flow control technique and for the design of ocean and civil engineering structures. With the increasing rotation rate, the variation of mean hydrodynamics has been discussed and the maximum mean hydrodynamics is considered to be decided by the rotation rate. According to these wake formations, the vortex shedding, weak vortex shedding, wake, and rotating wake areas are identified. Combining the initial, increasing, and equivalent areas for mean hydrodynamics, two different area-divisions have been conducted for mean hydrodynamics and the relationship between the two area-divisions has been illustrated. Finally, the disappearance of vortex shedding and variation of the Strouhal number have been discussed in detail. The critical value for the disappearance of vortex shedding is α ≈ 3.5, and the Strouhal number remains steady initially and then decreases.
Skyrmion fluctuations at a first-order phase transition boundary
Authors: Esposito V. , Zheng X. Y. , Seaberg M. H. , Montoya S. A. , Holladay B. , Reid A. H. , Streubel R. , Lee J. C. T. , Shen L. , Koralek J. D. , Coslovich G. , Walter P. , Zohar S. , Thampy V. , Lin M. F. , Hart P. , Nakahara K. , Fischer P. , Colocho W. , Lutman A. , Decker F.-J. , Sinha S. K. , Fullerton E. E. , Kevan S. D. , Roy S. , Dunne M. , Turner J. J.
Published: May 2020

Magnetic skyrmions are topologically protected spin textures with promising prospects for applications in data storage. They can form a lattice state due to competing magnetic interactions and are commonly found in a small region of the temperature—magnetic field phase diagram. Recent work has demonstrated that these magnetic quasi-particles fluctuate at the μeV energy scale. Here, we use a coherent x-ray correlation method at an x-ray free-electron laser to investigate these fluctuations in a magnetic phase coexistence region near a first-order transition boundary where fluctuations are not expected to play a major role. Surprisingly, we find that the relaxation of the intermediate scattering function at this transition differs significantly compared to that deep in the skyrmion lattice phase. The observation of a compressed exponential behavior suggests solid-like dynamics, often associated with jamming. We assign this behavior to disorder and the phase coexistence observed in a narrow field-window near the transition, which can cause fluctuations that lead to glassy behavior.
Embedded model discrepancy: A case study of Zika modeling
Authors: Morrison Rebecca E. , Cunha Americo
Published: May 2020

Mathematical models of epidemiological systems enable investigation of and predictions about potential disease outbreaks. However, commonly used models are often highly simplified representations of incredibly complex systems. Because of these simplifications, the model output, of, say, new cases of a disease over time or when an epidemic will occur, may be inconsistent with the available data. In this case, we must improve the model, especially if we plan to make decisions based on it that could affect human health and safety, but direct improvements are often beyond our reach. In this work, we explore this problem through a case study of the Zika outbreak in Brazil in 2016. We propose an embedded discrepancy operator—a modification to the model equations that requires modest information about the system and is calibrated by all relevant data. We show that the new enriched model demonstrates greatly increased consistency with real data. Moreover, the method is general enough to easily apply to many other mathematical models in epidemiology.
Influence of temperature on the soldering process of CLCC-3 package components using AuSn20 solder
Authors: Zhao Zhihuan , Gong Guanghao , Jiang Mingming , Chen Chuanzhong , Li Peng , Song Weihai , Zhao Zhibin , Zhang Li , Yu Huijun
Published: May 2020

In this study, a CLCC-3 shell and a cover were connected via soldering with AuSn20 as the solder. An Au–Sn eutectic reaction occurred during the sealing process. At high soldering temperatures, only the eutectic ζ′-Au5Sn and δ-AuSn phases remained. At the interface between the solder and the Au/Ni coating, Ni entered Au5Sn and AuSn to form (Au,Ni)5Sn and (Au,Ni)Sn and Au entered the lattice of the Ni3Sn2 phase to form the ternary compound (Ni,Au)3Sn2. The experimental results demonstrated that at a soldering heating plate temperature of 320 °C, the structure of the soldering area was compact and there were no holes in the soldering area. Under these conditions, the macroscopic appearance of the product improved, the solder was sufficiently melted, and the cover plate was well infiltrated, which resulted in the formation of a good, dense connection with the base plate.
The complex structural mechanisms behind strain curves in bismuth sodium titanate–barium titanate
Authors: Lee Kai-Yang , Shi Xi , Kumar Nitish , Hoffman Mark , Etter Martin , Winter Jens , Lemos da Silva Lucas , Seifert Daniela , Hinterstein Manuel
Published: May 2020

In this work, the lead-free composition (1-x)Bi0.5Na0.5TiO3–xBaTiO3 (BNT–BT) with x = 0.12 was investigated using in situ Synchrotron x-ray powder diffraction. With the applied electric field, the pseudo-cubic relaxor phase reversibly transforms to a ferroelectric state. The reversibility is still preserved after 104 bipolar electric field cycles. A Rietveld refinement with a structure, strain, and texture analysis using a model based on the atomic scale was applied for four frequencies from 10−4 to 101 Hz. The analysis allowed us to separately determine the two coexisting phases, their electric field dependent evolution, and the underlying strain mechanisms. For all the applied frequencies, we showed that domain switching is the only strain mechanism appearing in the tetragonal phase and the lattice strain is the only mechanism in the rhombohedral phase. The coercive field of the tetragonal phase (4 kV/mm) is found to be higher than that of the rhombohedral phase (3 kV/mm). This divergence has not been observed in previously investigated lead-containing materials and cannot be detected solely using macroscopic strain and polarization experiments. Moreover, the domain strain abruptly starts to occur only after a threshold field value and exhibits high hysteresis. The lattice strain, on the other hand, starts nearly from the beginning and increases more linearly during the bipolar field cycle. It could, therefore, be demonstrated that complex structural mechanisms underlie the apparent clear and continuous macroscopic strain curve. These findings are crucial for all actuator materials undergoing a relaxor to ferroelectric phase transformation and provide approaches and strategies to optimize lead-free materials for tailored applications.
Influence of upstream disturbances on the primary and secondary instabilities in a supersonic separated flow over a backward-facing step
Authors: Hu Weibo , Hickel Stefan , van Oudheusden Bas
Published: May 2020

The development of primary and secondary instabilities is investigated numerically for a supersonic transitional flow over a backward-facing step at Ma = 1.7 and Reδ0=13 718. Oblique Tollmien–Schlichting (T–S) waves with properties according to linear stability theory (LST) are introduced at the domain inlet with zero, low, or high amplitude (cases ZA, LA, and HA). A well-resolved large eddy simulation (LES) is carried out for the three cases to characterize the transition process from laminar to turbulent flow. The results for the HA case show a rapid transition due to the high initial disturbance level such that the non-linear interactions already occur upstream of the step, before the Kelvin–Helmholtz (K–H) instability could get involved. In contrast, cases ZA and LA share a similar transition road map in which transition occurs in the separated shear flow behind the step. Case LA is analyzed in detail based on the results from LST and LES to scrutinize the evolution of T–S, K–H, and secondary instabilities, as well as their interactions. Upstream of the step, the linear growth of the oblique T–S waves is the prevailing instability. Both T–S and K–H modes act as the primary mode within a short distance behind the step and undergo a quasi-linear growth with a weak coupling. Upon pairing of the large K–H vortices, subharmonic waves are produced, and secondary instabilities begin to dominate the transition. Simultaneously, the growth of T–S waves is retarded by the slow resonance between subharmonic K–H and secondary instabilities. The vortex breakdown and reattachment downstream further contribute to the development of the turbulent boundary layer.
Single-spin scanning magnetic microscopy with radial basis function reconstruction algorithm
Authors: Wang Cheng-Jie , Li Rui , Ding Bei , Wang Pengfei , Wang Wenhong , Wang Mengqi , Guo Maosen , Duan Chang-Kui , Shi Fazhan , Du Jiangfeng
Published: May 2020

Exotic magnetic structures, such as magnetic skyrmions and domain walls, are becoming more important in nitrogen-vacancy center scanning magnetometry. However, a systematic imaging approach to mapping stray fields with fluctuations of several milliteslas generated by such structures is not yet available. Here, we present a scheme to image a millitesla magnetic field by tracking the magnetic resonance frequency, which can record multiple contour lines for a magnetic field. The radial basis function algorithm is employed to reconstruct the magnetic field from the contour lines. Simulations with shot noise quantitatively confirm the high quality of the reconstruction algorithm. The method was validated by imaging the stray field of a frustrated magnet. Our scheme had a maximum detectable magnetic field gradient of 0.86 mT per pixel, which enables the efficient imaging of millitesla magnetic fields.
Water above the spinodal
Authors: Duška Michal
Published: May 2020

The liquid spinodal has long been discussed alongside the elusive liquid–liquid critical point hidden behind the limit of homogeneous nucleation. This has inspired numerous scenarios that attempt to explain water anomalies. Despite recent breakthrough experiments doubting several of those scenarios, we lacked a tool to localize the spinodal and the liquid–liquid critical point. We constructed a unique equation of state combining Speedy’s well known expansion and the liquid–liquid critical point to remove that deficit and to review these explanations. For the first time, the proposed equation of state independently depicts the spinodal in the presence of the liquid–liquid critical point and demonstrates that the explanation for water anomalies based on the reentrance of the spinodal is not valid; this feature (reentrance of the spinodal) was predicted because the density surface is curved by the presence of the second critical point. However, the critical point alone is not sufficient to explain the shape of the density surface of water. In the new equation, hydrogen bond cooperativity is important to force the critical point to exist outside of zero temperature. Together with the recent discovery of a compressibility maximum behind the homogeneous nucleation limit at positive pressure, the findings argue in favor of excluding all explanations for water anomalies except for the existence of the liquid–liquid critical point at positive pressure. Finally, an extensive study of heat capacity demonstrated profound disagreement between the two major experimental heat capacity datasets and identified the more accurate dataset.
Zn-induced layer exchange of p- and n-type nanocrystalline SiGe layers for flexible thermoelectrics
Authors: Tsuji M. , Kusano K. , Suemasu T. , Toko K.
Published: May 2020

Fermi-level control in a polycrystalline SiGe layer is challenging, especially under a low thermal budget owing to the low activation rate of impurities and defect-induced acceptors. Here, we demonstrate the low-temperature (120–350 °C) synthesis of nanocrystalline p- and n-type Si1−xGex (x: 0–1) layers using the layer exchange technique with a Zn catalyst. Pure Zn formed p-type SiGe layers (hole concentration: 1020 cm−3 for x ≥ 0.8) due to the shallow acceptor level of Zn in Ge. Conversely, As-doped Zn allowed us to synthesize n-type SiGe layers (electron concentration: 1019 cm−3 for x ≤ 0.3) at the lowest ever temperature of 350 °C, owing to the self-organized As doping to SiGe during layer exchange. The resulting p-type Si0.2Ge0.8 and n-type Si0.85Ge0.15 layers exhibited the largest ever power factors (280 μW/mK2 for the p-type and 15 μW/mK2 for the n-type), for SiGe fabricated on a flexible plastic sheet. The low-temperature synthesis technology, for both p- and n-type SiGe layers, opens up the possibility of developing human-friendly, highly reliable, flexible devices including thermoelectric sheets.
A 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HAT-CN) transport layer with high electron mobility for thick organic light-emitting diodes
Authors: Yamaguchi Kenta , Esaki Yu , Matsushima Toshinori , Adachi Chihaya
Published: May 2020

In our previous paper [T. Matsushima et al., Nature 572, 502 (2019)], current densities of organic light-emitting diodes (OLEDs) did not decrease significantly when the thicknesses of a 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HAT-CN) transport layer were increased from tens of nanometers to 1 μm. To make this mechanism clear, we carried out several experiments in terms of electron transfer with other organic layers and electron mobility of HAT-CN. Finally, we found that the vacuum-evaporated HAT-CN layers have very high electron mobility and, therefore, using a HAT-CN transport layer can suppress the decrease in current density even in thick OLEDs. The electron mobility of vacuum-deposited HAT-CN layers, which was measured using analysis with a space-charge-limited current model, was 0.1–1 cm2 V−1 s−1. This electron mobility is much higher than those of conventional organic transport layers used in OLEDs (<10−3 cm2 V−1 s−1) even though the HAT-CN layers are amorphous-like. We attributed one of the reasons for this extraordinarily high mobility to be a better overlap of π orbitals in the substrate normal, which is associated with horizontally oriented HAT-CN molecules on a substrate.
An interface-controlled Mott memristor in
α
-RuCl3
Authors: Frick Jordan R. , Sridhar Samanvitha , O'Donnell Shaun , Maggard Paul A. , Dougherty Daniel B.
Published: May 2020

Memristor devices have history-dependent charge transport properties that are ideal for neuromorphic computing applications. We reveal a memristor material and mechanism in the layered Mott insulator α-RuCl3. The pinched hysteresis loops and S-shaped negative differential resistance in bulk crystals verify memristor behavior and are attributed to a nonlinear coupling between charge injection over a Schottky barrier at the electrical contacts and concurrent Joule heating. Direct simulations of this coupling can reproduce the device characteristics.
Tracing culture in children’s thinking: a socioecological framework in understanding nature (Rastreando la cultura en el pensamiento infantil: una socioecología para comprender la naturaleza)
Authors: Taverna Andrea S. , Medin Douglas L. , Waxman Sandra R.
Published: May 2020

There is considerable agreement that cognitive development is shaped by culture. Less clear, however, is the mechanism by which culture exerts its influence as cognition unfolds. Prior work has primarily focused on culture as a species-specific medium of cognitive development or as an explicative factor of cognitive capacities. Here we describe a more recent alternative, the culture-as-ecosystem approach. In this view, concepts are embedded within epistemological orientations providing pervasive, widely distributed framework theories that organize people’s knowledge, learning and behaviour. To illustrate the promise of this approach, we review new evidence about how the Wichi, an indigenous population from the Chaco region in North Argentina, reason about hunhat lheley (inhabitants of the earth). By adopting the culture-as-ecosystem approach, we identified a distinct socioecological framework, undocumented elsewhere. This framework, evidenced in young children and adults, is well aligned with Wichi epistemology. We hope that highlighting the theoretical promise and empirical power of the culture-as-ecosystem approach will offer new insights into the intriguing interface between culture and cognition in development.
‘Ramseyfying’ Probabilistic Comparativism
Authors: Elliott Edward
Published: May 2020

Comparativism is the view that comparative confidences (e.g., being more confident thatPthan thatQ) are more fundamental than degrees of belief (e.g., believing thatPwith some strengthx). I outline the basis for a new, nonprobabilistic version of comparativism inspired by a suggestion made by Frank Ramsey in “Probability and Partial Belief.” I show how, and to what extent, ‘Ramseyan comparativism’ might be used to weaken the (unrealistically strong) probabilistic coherence conditions that comparativism traditionally relies on.
Coaxial Multi-Wavelength Generation in YVO4 Crystal with Stimulated Raman Scattering Excited by a Picosecond-Pulsed 1064 Laser*
Authors: Hao Jing-Jie , Tu Wei , Zong Nan , Shen Yu , Zhang Shen-Jin , Bo Yong , Peng Qin-Jun , Xu Zu-Yan
Published: May 2020

The multiwavelength characteristics of stimulated Raman scattering (SRS) in YVO
4
crystal excited by a picosecond laser at 1064nm are investigated theoretically and experimentally. Laser output with seven wavelengths is achieved coaxially and synchronously at 894, 972, 1175, 1312, 1486, 1713 and 2022nm in a YVO
4
crystal. The maximum total Raman output energy is as high as 2.77 mJ under the pump energy of 7.75 mJ. A maximum total Raman conversion efficiency of 47.8% is obtained when the pump energy is 6.54 mJ. This is the highest order of Stokes components and the highest output energy generated by YVO
4
reported up to date. This work expands the Raman spectrum of YVO
4
crystal to the near-IR regime, with seven wavelengths covered at the same time, paving the way for new wavelength generation in the near-IR regime and its multiwavelength application.
Metal to Orthogonal Metal Transition*
Authors: Chen Chuang , Xu Xiao Yan , Qi Yang , Meng Zi Yang
Published: May 2020

Orthogonal metal is a new quantum metallic state that conducts electricity but acquires no Fermi surface (FS) or quasiparticles, and hence orthogonal to the established paradigm of Landau’s Fermi-liquid (FL). Such a state may hold the key of understanding the perplexing experimental observations of quantum metals that are beyond FL, i.e., dubbed non-Fermi-liquid (nFL), ranging from the Cu- and Fe-based oxides, heavy fermion compounds to the recently discovered twisted graphene heterostructures. However, to fully understand such an exotic state of matter, at least theoretically, one would like to construct a lattice model and to solve it with unbiased quantum many-body machinery. Here we achieve this goal by designing a 2D lattice model comprised of fermionic and bosonic matter fields coupled with dynamic ℤ2 gauge fields, and obtain its exact properties with sign-free quantum Monte Carlo simulations. We find that as the bosonic matter fields become disordered, with the help of deconfinement of the ℤ2 gauge fields, the system reacts with changing its nature from the conventional normal metal with an FS to an orthogonal metal of nFL without FS and quasiparticles and yet still responds to magnetic probe like an FL. Such a quantum phase transition from a normal metal to an orthogonal metal, with its electronic and magnetic spectral properties revealed, is calling for the establishment of new paradigm of quantum metals and their transition with conventional ones.
Advances in traceable calibration of cylinder pressure transducers
Authors: Salminen J , Saxholm S , Hämäläinen J , Högström R
Published: May 2020

Accurate and reliable dynamic pressure measurements are needed for optimizing performance in modern combustion engines, manufacturing processes and aerospace applications. Besides fast pressure transients, these applications subject dynamic pressure transducers to elevated temperatures. Both of these quantities effect the sensitivity of transducers. Therefore, transducers should be calibrated at conditions that corresponds to the operating environment.

To answer these needs, the National Metrology Institute VTT MIKES has developed its drop weight dynamic pressure primary standard further. Developments include improved control and measurement of the falling weight, extension of the pressure range to combustion engine pressures down to 3 MPa and a heating option for dynamic pressure transducers under calibration. These advances enable traceable calibration of cylinder pressure transducers at conditions relevant to engine applications. The overall uncertainty (k = 2) of calibration is estimated to be around 1.7%. The performance was demonstrated by calibrating a piezoelectric pressure transducer in the pressure and temperature range from 7 MPa to 30 MPa in 20 °C, 120 °C and 180 °C, respectively. As a result, traceable calibrations of dynamic pressure transducers can be performed at conditions relevant for engine applications. This improves the reliability and accuracy of in-cylinder pressure measurements.
Satellite-derived foresummer drought sensitivity of plant productivity in Rocky Mountain headwater catchments: spatial heterogeneity and geological-geomorphological control
Authors: Wainwright Haruko M , Steefel Christoph , Trutner Sarah D , Henderson Amanda N , Nikolopoulos Efthymios I , Wilmer Chelsea F , Chadwick K Dana , Falco Nicola , Schaettle Karl Bernard , Brown James Bentley , Steltzer Heidi , Williams Kenneth H , Hubbard Susan S , Enquist Brian J
Published: May 2020

Long-term plot-scale studies have found water limitation to be a key factor driving ecosystem productivity in the Rocky Mountains. Specifically, the intensity of early summer (the ‘foresummer’ period from May to June) drought conditions appears to impose critical controls on peak ecosystem productivity. This study aims to (1) assess the importance of early snowmelt and foresummer drought in controlling peak plant productivity, based on the historical Landsat normalized-difference vegetation index (NDVI) and climate data; (2) map the spatial heterogeneity of foresummer drought sensitivity; and (3) identify the environmental controls (e.g. geomorphology, elevation, geology, plant types) on drought sensitivity. Our domain (15 × 15 km) includes four drainages within the East Water watershed near Gothic, Colorado, USA. We define foresummer drought sensitivity based on the regression slopes of the annual peak NDVI against the June Palmer Drought Severity Index between 1992 and 2010. Results show that foresummer drought sensitivity is spatially heterogeneous, and primarily dependent on the plant type and elevation. In support of the plot-based studies, we find that years with earlier snowmelt and drier foresummer conditions lead to lower peak NDVI; particularly in the low-elevation regions. Using random forest analysis, we identify additional key controls related to surface energy exchanges (i.e. potential net radiation), hydrological processes (i.e. microtopography and slope), and underlying geology. This remote-sensing-based approach for quantifying foresummer drought sensitivity can be used to identify the regions that are vulnerable or resilient to climate perturbations, as well as to inform future sampling, characterization, and modeling studies.
An electric concentrator and thermal cloaking device
Authors: Raza Muhammad
Published: May 2020

The concentration and cloaking phenomena of physical fields in Metamaterials has captured the attention of the researchers due to their simplified approaches. However most of the work conducted is focussed on controlling single physical field. Transformation optics has paved the way for developing intelligent bifunctional devices. Bifunctional devices are such controlled devices which execute two different physical functions simultaneously and independently. In this work we have applied the transformation optics theory to design a multilayered two dimensional spherical bifunctional device which behaves like an electric concentrator and thermal invisibility cloak simultaneously. Moreover, we have also observed the normalized behavior of the proposed device. The simulation performance confirms the feasibility of our suggested model.
Rainfall control on Amazon sediment flux: synthesis from 20 years of monitoring
Authors: Armijos E , Crave A , Espinoza J C , Filizola N , Espinoza-Villar R , Ayes  , Fonseca P , Fraizy P , Gutierrez O , Vauchel P , Camenen B , Martiınez J M , Dos Santos A , Santini W , Cochonneau G , Guyot J L
Published: May 2020

The biodiversity and productivity of the Amazon floodplain depend on nutrients and organic matter transported with suspended sediments. Nevertheless, there are still fundamental unknowns about how hydrological and rainfall variability influence sediment flux in the Amazon River. To address this gap, we analyzed 3069 sediment samples collected every 10 days during 1995–2014 at five gauging stations located in the main rivers. We have two distinct fractions of suspended sediments, fine (clay and silt) and coarse (sand), which followed contrasting seasonal and long-term patterns. By taking these dynamics into account, it was estimated, for first time, in the Amazon plain, that the suspended sediment flux separately measured approximately 60% fine and 40% coarse sediment. We find that the fine suspended sediments flux is linked to rainfall and higher coarse suspended sediment flux is related with discharge. Additionally this work presents the time lag between rainfall and discharge, which is related to the upstream area of the gauging. This result is an important contribution to knowledge of biological and geomorphological issues in Amazon basin.
Codex
Authors: Brown Michelle P.
Published: May 2020

The codex occupies an iconic role in Western culture. Usually narrowly applied to the folded book form of the age of print, it owes its origins and development to pre-print manuscript culture. As early as the 1st century ce, the Roman poet Martial was recommending that his readers buy the new codex form. But then, as now, publishers were slow to retool, and the ancient scroll technology continued until the 4th century, when the codex, initially the preserve of the underclasses (notably the early Christians, who valued it for its portability and cross-referencing suitability), achieved popularity as the focus of Christianity, a religion of the book. Wax tablets—the less formal medium of the day—continued in use for drafting of text and image and for informal purposes into the early 20th century. From the 5th century onward the use of decoration and paratextual features such as punctuation served to help navigate and articulate the text and images, illustrated the narrative, or explored the multivalent meaning of text through image.

Both men and women, religious and secular, wealthy or poor, figured in the production of medieval books, as authors, makers, and users. Documentary evidence and that detected within the books themselves gives a picture of the ways in which literary works were composed, captured in writing, published, disseminated, and accessed. Each manuscript is unique, but together they provide a portal into a thousand years of thought.
Philology
Authors: Lönnroth Harry
Published: May 2020

Philology—from the Greek words philologi’ā < philos “friend” and logos “word”—is a multi-faceted field of scholarship within the humanities which in its widest sense focuses on questions of time, history, and literature—with language as the common denominator. Philology is both an academic discipline—there is classical philology, Romance philology, Scandinavian philology, etc.—and a scholarly perspective on language, literature, and culture. The roots of philology go back all the way to the Library of Alexandria, Egypt, where philology began to evolve into a field of scholarship around 300 bce. In Alexandria, the foundations of philology were laid for centuries to come, for example as regards one of its major branches, textual criticism. A characteristic feature of philology past and present is that it focuses on texts in time from an interdisciplinary point of view, which is why philology as an umbrella term is relevant for many fields of scholarship in the 21st century. According to a traditional definition, a philologist is interested in the relationship between language and culture, and by means of language, he or she aims to understand the characteristics of the culture the language reflects. From this point of view, language is mainly a medium. In the analysis of (mostly very old) texts, a philologist often crosses disciplinary borders of different kinds—anthropology, archaeology, ethnology, folkloristics, history, etc.—and makes use of other special fields within manuscript studies, such as codicology (the archaeology of the book), diplomatics (the analysis of documents), paleography (the study of handwriting), philigranology (watermarks), and sphragistics (seals). For a philologist, texts and their languages and contents bear witness to past times, and the philologist’s perspective is often a wide one. The expertise of a philologist is the ability to analyze texts in their cultural-historical contexts, not only from a linguistic perspective (which is a prerequisite for a deep understanding of a text), but also from a cultural and historical perspective, and to explain the role of a text in its cultural-historical setting. In the course of history, philologists have made several contributions to our knowledge of ancient and medieval texts and writing, for example. In the 2010s, the focus in philology is for example on the so-called New Philology or Material Philology and digital philology, but the core of philology remains the same: philology is the art of reading slowly.