bluuebunny/crossref_metadata_2025 huggingface dataset:
Angle-tunable intersubband photoabsorption and enhanced photobleaching in twisted bilayer graphene
Authors: Pogna Eva A. A. , Miao Xianchong , von Dreifus Driele , Alencar Thonimar V. , Moutinho Marcus V. O. , Venezuela Pedro , Manzoni Cristian , Ji Minbiao , Cerullo Giulio , de Paula Ana Maria
Published: January 2021

Van der Waals heterostructures obtained by artificially stacking two-dimensional crystals represent the frontier of material engineering, demonstrating properties superior to those of the starting materials. Fine control of the interlayer twist angle has opened new possibilities for tailoring the optoelectronic properties of these heterostructures. Twisted bilayer graphene with a strong interlayer coupling is a prototype of twisted heterostructure inheriting the intriguing electronic properties of graphene. Understanding the effects of the twist angle on its out-of-equilibrium optical properties is crucial for devising optoelectronic applications. With this aim, we here combine excitation-resolved hot photoluminescence with femtosecond transient absorption microscopy. The hot charge carrier distribution induced by photo-excitation results in peaked absorption bleaching and photo-induced absorption bands, both with pronounced twist angle dependence. Theoretical simulations of the electronic band structure and of the joint density of states enable to assign these bands to the blocking of interband transitions at the van Hove singularities and to photo-activated intersubband transitions. The tens of picoseconds relaxation dynamics of the observed bands is attributed to the angle-dependence of electron and phonon heat capacities of twisted bilayer graphene.
Productive performance of organic crop farms in Finland 2010–2017
Authors: Kuosmanen Natalia , Yli-Heikkilä Maria , Väre Minna , Kuosmanen Timo
Published: January 2021

Increasing organic production is one of the strategic objectives of the Finnish agricultural policy. Despite the positive developments observed during the last decade, reaching the objectives set by the Finnish government remains challenging. The contributions of this study are twofold. Firstly, this study provides new empirical evidence on productive performance of organic crop farming in Finland and explains observed gap between average output of organic and conventional farms. Specifically, we use the most recent available farm-level data and analyze the performance of organic crop farms over the period 2010–2017. Secondly, to estimate the performance gap between the organic and conventional crop farms, we apply one-stage semi-nonparametric regression. This approach alleviates the endogeneity problem of the commonly used two-stage estimation approaches, providing robust estimates without restrictive functional form assumptions. Our results reveal a significant performance gap between organic and conventional farming. However, the difference between productive performance of organic and conventional crop farms has been decreasing over the years. Moreover, a positive trend is revealed in organic production at the end of the study period.
Cosmic Bayes. Datasets and priors in the hunt for dark energy
Authors: Massimi Michela
Published: January 2021

Bayesian methods are ubiquitous in contemporary observational cosmology. They enter into three main tasks: (I) cross-checking datasets for consistency; (II) fixing constraints on cosmological parameters; and (III) model selection. This article explores some epistemic limits of using Bayesian methods. The first limit concerns the degree of informativeness of the Bayesian priors and an ensuing methodological tension between task (I) and task (II). The second limit concerns the choice of wide flat priors and related tension between (II) parameter estimation and (III) model selection. The Dark Energy Survey (DES) and its recent Year 1 results illustrate both these limits concerning the use of Bayesianism.
Correction to: ZFP281 recruits polycomb repressive complex 2 to restrict extraembryonic endoderm potential in safeguarding embryonic stem cell pluripotency
Authors: Huang Xin , Bashkenova Nazym , Yang Jihong , Li Dan , Wang Jianlong
Published: January 2021

In the original publication the labelling in middle and bottom panels of figure 2k is published incorrectly as “Soc17”. The correct labeling is available in this correction as “Sox17”.
Aquaculture-capture fisheries nexus under Covid-19: impacts, diversity, and social-ecological resilience
Authors: Manlosa Aisa O. , Hornidge Anna-Katharina , Schlüter Achim
Published: January 2021

The Covid-19 pandemic is a global shock that is significantly affecting coastal social-ecological systems (SES) in different parts of the world. Its widespread impacts have unravelled vulnerabilities in many aspects of society, including food systems. Our study investigated the impacts of a lockdown associated with the pandemic in the province of Bulacan, in the region of Central Luzon, Philippines, where aquaculture and capture fisheries are important and interconnected sectors. In particular, we focused on impacts related to production and market. We considered people’s coping strategies and the factors that enabled such strategies. Our investigation adopted a case study approach and drew on qualitative data analysed through thematic analysis. The findings revealed differentiated mechanisms through which aquaculture and capture fisheries production were impacted. Both were strongly affected by market disruptions but through slightly different ways. In effect, the lockdown provided the impetus for the uptake and spreading of practices that were previously peripheral, particularly in relation to market exchanges. The study also identified a variety of coping strategies, as well as the importance of social support in the form of food aid, financial assistance, and institutional livelihood assistance. Finally, it discusses the importance of diversity in food sources, the role of local food systems, and governance implications for foregrounding social-ecological resilience in short-term response and long-term recovery.
Altitude Aerosol Measurements in Central France: Seasonality, Sources and Free‐Troposphere/Boundary Layer Segregation
Authors: Farah A. , Freney E. , Canonaco F. , Prévôt A. S. H. , Pichon J‐M. , Abboud M. , Farah W. , Sellegri K.
Published: January 2021

The chemical composition of nonrefractory submicron aerosol particles was measured at the Puy‐de‐Dôme (PUY) station (1,465 m a.s.l) during 2015 using a Time‐of‐Flight Aerosol Chemical Speciation Monitor (ToF‐ACSM). These aerosol chemistry measurements are combined with online black carbon (BC) measurements to provide an overview of the submicron aerosol composition. Averaged over the entire year, and normalized to standard temperature and pressure, organic aerosol (OA) dominates the PM1 concentration during all seasons and within all air mass types (2.12 ± 1.73 µgm−3), and is responsible for summertime increases in aerosol concentration. Highest mass concentrations were measured during the summer, when air masses were arriving over mainland Europe and lowest in the winter months (when most air masses were of Atlantic origin). OA source apportionment was performed separately during each season, using the Source Finder (SoFi) interface for the multilinear engine. The PUY site, situated at 1,465 m a.s.l, although mainly sampling in the atmospheric boundary layer, it is sometimes sampling in the lower free troposphere (FT), providing the opportunity to identify the characteristics of FT aerosol. In order to accurately identify these sampling periods, the methodology described in Farah et al. (2018), during the same time period (2015/2016), was applied to the data. During this period, FT air masses are sampled approximately 20% of the time. This work provides, on one hand, a description of long‐term aerosol chemical properties at a remote regional site in central Europe and, on the other hand a characteristic chemical signature of FT aerosols over this region. This data can be used to improve our understanding of the transport and aging properties of aerosols at regional observation sites.
On the Relationship Between the Madden‐Julian Oscillation and the Hadley and Walker Circulations
Authors: Schwendike Juliane , Berry Gareth J. , Fodor Katherine , Reeder Michael J.
Published: January 2021

This study investigates: (i) how the local meridional (Hadley) and zonal (Walker) circulations change in each phase of the Madden‐Julian Oscillation (MJO); and (ii) the effect of enhanced and suppressed MJO‐related convection on the poleward extent of the local Hadley circulations and, thus, the strengths and positions of the subtropical jets. We examine these effects in ERA‐Interim reanalysis by decomposing the vertical mass flux into zonal and meridional components. We show for the first time, that as the envelope of enhanced convection moves eastwards from Africa to the Central Pacific the local Hadley circulation is enhanced. The regional Walker circulation in the Pacific is strengthened when the envelope of active MJO convection is located over the Maritime Continent and weakened when the region of suppressed convection is located there. In regions of anomalous upper‐level divergence the subtropical jet is enhanced. The core of the subtropical jet over Asia shifts eastwards with the progression of the MJO and shifts farther poleward in regions of anomalous upper‐level divergence linked with enhanced convection. The region of either enhanced or suppressed convection over the Maritime Continent strengthens or weakens the local Hadley circulation, producing disturbances in the subtropical jet. These disturbances then force midlatitude Rossby waves that propagate across the Pacific Ocean in both hemispheres.
Deep Space Observations of Terrestrial Glitter
Authors: Kostinski Alexander , Marshak Alexander , Várnai Tamás
Published: January 2021

Deep space climate observatory (DSCOVR) spacecraft drifts about the Lagrangian point ≈1.4–1.6 × 106 km from Earth, where its Earth polychromatic imaging camera (EPIC) observes the sun‐lit face of the Earth every 1 to 2 hours. At any instance, there is a preferred (specular) spot on the globe, where a glint may be observed by EPIC. While monitoring reflectance at these spots (terrestrial glitter), we observe occasional intense glints originating from neither ocean surface nor cloud ice and we argue that mountain lakes high in the Andes are among the causes. We also examine time‐averaged reflectance at the spots and find it exceeding that of neighbors, with the excess monotonically increasing with separation distance. This specular excess is found in all channels and is more pronounced in the latest and best‐calibrated version of EPIC data, thus opening the possibility of testing geometric calibration by monitoring distant glitter.
Leaf Trait Plasticity Alters Competitive Ability and Functioning of Simulated Tropical Trees in Response to Elevated Carbon Dioxide
Authors: Kovenock Marlies , Koven Charles D. , Knox Ryan G. , Fisher Rosie A. , Swann Abigail L. S.
Published: January 2021

The response of tropical ecosystems to elevated carbon dioxide (CO2) remains a critical uncertainty in projections of future climate. Here, we investigate how leaf trait plasticity in response to elevated CO2 alters projections of tropical forest competitive dynamics and functioning. We use vegetation demographic model simulations to quantify how plasticity in leaf mass per area and leaf carbon to nitrogen ratio alter the responses of carbon uptake, evapotranspiration, and competitive ability to a doubling of CO2 in a tropical forest. Observationally constrained leaf trait plasticity in response to CO2 fertilization reduces the degree to which tropical tree carbon uptake is affected by a doubling of CO2 (up to −14.7% as compared to a case with no plasticity; 95% confidence interval [CI95%] −14.4 to −15.0). It also diminishes evapotranspiration (up to −7.0%, CI95% −6.4 to −7.7), and lowers competitive ability in comparison to a tree with no plasticity. Consideration of leaf trait plasticity to elevated CO2 lowers tropical ecosystem carbon uptake and evapotranspirative cooling in the absence of changes in plant‐type abundance. However, “plastic” responses to high CO2 which maintain higher levels of plant productivity, many of which fall outside of the observed range of response, are potentially more competitively advantageous, thus, including changes in plant type abundance may mitigate these decreases in ecosystem functioning. Models that explicitly represent competition between plants with alternative leaf trait plasticity in response to elevated CO2 are needed to capture these influences on tropical forest functioning and large‐scale climate.
Conjugate Ionospheric Perturbation During the 2017 Solar Eclipse
Authors: Zhang Shun‐Rong , Erickson Philip J. , Vierinen Juha , Aa Ercha , Rideout William , Coster Anthea J. , Goncharenko Larisa P.
Published: January 2021

We report new findings of total electron content (TEC) perturbations in the southern hemisphere at conjugate locations to the northern eclipse on August 21, 2017. We identified a persistent conjugate TEC depletion by 10%–15% during the eclipse time, elongating along magnetic latitudes with at least ∼5° latitudinal width. As the Moon's shadow swept southward, this conjugate depletion moved northward and became most pronounced at lower magnetic latitudes (>−20°N). This depletion was coincident with a weakening of the southern crest of the equatorial ionization anomaly (EIA), while the northern EIA crest stayed almost undisturbed or was slightly enhanced. We suggest these conjugate perturbations were associated with dramatic eclipse initiated plasma pressure reductions in the flux tubes, with a large portion of shorter tubes located at low latitudes underneath the Moon's shadow. These short L‐shell tubes intersect with the F region ionosphere at low and equatorial latitudes. The plasma pressure gradient was markedly skewed northward in the flux tubes at low and equatorial latitudes, as was the neutral pressure. These effects caused a general northward motion tendency for plasma within the flux tubes, and inhibited normal southward diffusion of equatorial fountain plasma into the southern EIA region. We also identified posteclipse ionospheric disturbances likely associated with the global propagation of eclipse‐induced traveling atmospheric disturbances in alignment with the Moon's shadow moving direction.
Effects of the Space Plasma Density Oscillation on the Interspacecraft Laser Ranging for TianQin Gravitational Wave Observatory
Authors: Lu Ling‐Feng , Su Wei , Zhang Xuefeng , He Zhao‐Guo , Duan Hui‐Zong , Jiang Yuan‐Ze , Yeh Hsien‐Chi
Published: January 2021

The TianQin space gravitational waves (GW) observatory will contain three geocentric and circularly orbiting spacecraft with an orbital radius of 105 km, to detect the GW in the milli‐hertz frequency band. Each spacecraft pair will establish a 1.7 × 105 km‐long laser interferometer immersed in the solar wind and the magnetospheric plasmas to measure the phase deviations induced by the GW. GW detection requires a high‐precision measurement of the laser phase. The cumulative effects of the long distance and the periodic oscillations of the plasma density may induce an additional phase noise. This study aims to model the plasma induced phase deviation of the interspacecraft laser signals, using a realistic orbit simulator and the Space Weather Modeling Framework model. Preliminary results show that the plasma density oscillation can induce the phase deviations close to 2 × 10−6 rad/Hz1/2 or 0.3 pm/Hz1/2 in the milli‐hertz frequency band and it is within the error budget assigned to the displacement noise of the interferometry. The amplitude spectrum density of phases along three arms become more separated when the orbital plane is parallel to the Sun‐Earth line or during a magnetic storm. Finally, the dependence of the phase deviations on the orbital radius is examined.
A Theory of Interaction Between Relativistic Electrons and Magnetospherically Reflected Whistlers
Authors: Shklyar David R.
Published: January 2021

Whistlers that originate from lightning strokes are among the prevalent wave phenomena in the magnetosphere, which makes their interactions with magnetospheric plasma particles of particular importance. We develop a theory that takes into account the main features of this interaction, namely, the space‐time boundedness of wave packets representing magnetospherically reflected whistlers, and the variation of frequency, wave normal vector, and amplitude inside wave packets. We take into account the inhomogeneity of the ambient plasma and the geomagnetic field, as well as relativistic effects in particle dynamics. A particular emphasis is placed on energy exchange between resonant particles as an intrinsic component part of wave‐particle interaction in plasma.
Modeling Optical Properties of Non‐Cubical Sea‐Salt Particles
Authors: Kanngießer Franz , Kahnert Michael
Published: January 2021

Dry sodium chloride forms cubic crystals, while marine aerosol particles often display more or less irregular deviations from this ideal form. In this study, three non‐ideal cuboidal and octahedral model geometries are investigated. Superellipsoids are tested as a model to simulate the linear backscatter depolarization ratio and the extinction‐to‐backscatter ratio. Gaussian random cubes as well as convex polyhedra are investigated as possible model candidates to quantify the error introduced by simplified model geometries, such as superellipsoids. Uncertainties in the real and imaginary part of the refractive index are studied, and their effect on the optical properties is compared to that caused by morphological variations. Optical calculations were performed at a wavelength of 532 nm using the discrete dipole approximation and the T‐matrix method. The considered size range is representative for marine aerosol generated at low to moderate wind speeds. It is found that cuboidal superellipsoids predict depolarization and extinction‐to‐backscatter ratios that are consistent with observations. On the other hand, octahedral superellipsoids strongly overestimate the depolarization ratio. Gaussian random surface perturbations result in a positive shift of the depolarization ratio compared to cuboidal superellipsoids. By contrast, convex polyhedra yield results that more or less randomly scatter about those of regular cubes. Thus, convex polyhedra are a promising candidate for modeling random errors, while Gaussian random cubes are not. Uncertainties in the refractive index result in perturbations of the depolarization and extinction‐to‐backscatter ratio that are of comparable magnitude as those caused by perturbations of the geometry.
Lidar Observations and Numerical Simulations of an Atmospheric Hydraulic Jump and Mountain Waves
Authors: Peña A. , Santos P.
Published: January 2021

An atmospheric hydraulic jump was observed over the Alaiz mountain range and Elorz valley near Pamplona, Spain from radial velocity retrievals performed with two scanning lidars during October 5 and 6, 2018. The jump occurred on the lee side of the mountain close to its base and the jump location was observed more than 2 km further downstream of the mountain base inside the valley. Here, we simulate the two days using the multi‐scale modeling capabilities of the Weather Research and Forecasting model. We find that the model is able to reproduce the hydraulic jump in high detail matching qualitatively well the timing and main features observed by both the scanning lidars and meteorological instruments on masts deployed throughout the area. The simulation results show that the jump starts at the beginning of the evening, right after the atmospheric conditions over the top of the Alaiz mountain become stable and the flow at the mountain top experiences a transition from subcritical to supercritical. The simulations also show that the jump lasts about 10 h until it moves close to the mountain top; then lee‐wave activity dominates and lasts until late in the morning. The flow at the mountain top is only supercritical during the periods where the jump and the lee waves take place. The jump and lee‐wave regimes can be distinguished from the simulation results by analyzing the ratio of the depth‐average Brunt‐Väisälä frequency to the depth‐average mean wind speed both upstream and downstream of the mountain top.
Bulk, Spectral and Deep Water Approximations for Stokes Drift: Implications for Coupled Ocean Circulation and Surface Wave Models
Authors: Liu Guoqiang , Kumar Nirnimesh , Harcourt Ramsey , Perrie William
Published: January 2021

Surface waves modify upper ocean dynamics through Stokes drift related processes. Stokes drift estimated from a discrete wave spectrum is compared to Stokes drift approximations as a monochromatic profile based on bulk surface wave parameters, and to two additional superexponential functional forms. The impact of these different methods on ocean processes is examined in two test‐bed cases of a wave‐current coupled system: (1) a wind‐free shallow water inlet test case and (2) an idealized deep water hurricane case with high varying winds. In case (1), tidal currents and bathymetry can modify the waves and significantly affect Stokes drift computed from the wave spectrum. In case (2), rapid variation in atmospheric stress at high wind speed generates large departures from fully developed equilibrium seas. In both cases, large deviations in ocean current response are produced when the Stokes drift is approximated monochromatically from bulk wave parameters, rather than from integration over the wave spectra. Deep water simulations using the two superexponential approximations are in better agreement with those estimated from wave spectra than are those using the monochromatic, exponential profile based on bulk wave parameters. In order to represent the impact of Stokes drift at resolved scales, we recommend that for studies of nearshore processes and deep water events, like wave‐current interactions under storms, the Stokes drift should be calculated from full wave spectra. For long simulations of open ocean dynamics, methods using superexponential profiles to represent equilibrium wind seas might be sufficient, but appear to be marginally more computationally efficient.
Pool‐Riffle Adjustment Due to Changes in Flow and Sediment Supply
Authors: Hassan Marwan A. , Radić Valentina , Buckrell Emma , Chartrand Shawn M. , McDowell Conor
Published: January 2021

How do gravel bed pool‐riffle streams adjust to changing upstream water and bedload sediment supplies, and what analysis techniques can help to effectively identify how change occurs? Here, we use a mixture of field and experimental data to examine these problems and apply a suite of traditional and novel analysis approaches to highlight dynamics which might otherwise go undetected. Eleven years of monitoring channel morphology in a small forested watershed indicate that pool‐riffles persist through large changes in upstream water and bedload supply and that bed architecture relief is correlated to flow magnitude. A flume experiment consisting of eight runs was conducted to examine the field case in more detail. The experimental design splits the eight runs into four runs of relatively high water and sediment supply and four of relatively low water supply, with no upstream sediment supply. Experimental results corroborate the field‐based measurements of pool‐riffle persistence, which is due to a coupling between downstream width variations, and spatial patterns of flow velocity and bedload transport. More specifically, measurements made during the flume experiments along a prominent pool‐riffle pair indicate that temporal and spatial changes to topography, flow hydraulics, and bed surface sediment texture are more rich and nuanced than existing generalizations offer. For example, clustering analysis completed using self‐organizing maps indicates that sediment sorting between pools and riffles is not simply a binary type response of finer versus coarser described by some characteristic grain size.
Mn–DNA coordination of nanoparticles for efficient chemodynamic therapy
Authors: Lin Li , Yu Jiantao , Lu Hongwei , Wei Zixiang , Chao Zhicong , Wang Zhongling , Wu Weitao , Jiang Hengfeng , Tian Leilei
Published: January 2021

Manganese ions were efficiently delivered by long single strand DNA ligands and caused the apoptosis of cancer cells by the Fenton-like reaction.
Structurally reconstituted calcium manganate nanoparticles as a high-performance cathode for aqueous Zn-ion batteries
Authors: Zeng Siqi , Xu Wei , Zheng Dezhou , Zhang Haozhe , Wang Fuxin , Liu Xiaoqing , Lu Xihong
Published: January 2021

This work demonstrates a kind of Ca-deficient Ca0.96Mn3.04O4 nanoparticle framework derived from α-MnO2-like CaMn2O4via structural reconstruction strategy as promising cathode materials for aqueous Zn-ion batteries.
Exfoliated conjugated porous polymer nanosheets for highly efficient photocatalytic hydrogen evolution
Authors: Cheng Jing-Zhao , Tan Zhi-Rong , Xing Yu-Qin , Shen Zhao-Qi , Zhang Yu-Jie , Liu Li-Lin , Yang Kai , Chen Long , Liu Shi-Yong
Published: January 2021

A common strategy is developed to exfoliate bulk CPPs into nanosheets for highly efficient PHP performance.
High-efficiency and thermal/moisture stable CsPbI2.84Br0.16 inorganic perovskite solar cells enabled by a multifunctional cesium trimethylacetate organic additive
Authors: Zhao Hang , Fu Yao , Li Zhenzhen , Yang Shujie , Xu Baomin , Liu Xiaolong , Xu Jia , Liu Shengzhong (Frank) , Yao Jianxi
Published: January 2021

A cesium trimethylacetate (CsTa) organic cesium salt with large steric hindrance radius and strong binding force to Pb2+ show the positive effects on inorganic CsPbI2.84Br0.16 perovskite stability.
Rational catalyst design for oxygen evolution under acidic conditions: strategies toward enhanced electrocatalytic performance
Authors: Zhang Yu , Zhu Xiaojuan , Zhang Guanglu , Shi Peidong , Wang An-Liang
Published: January 2021

Several catalyst design strategies for enhanced OER performance under acidic conditions were summarized, which could provide guidance for the synthesis of more efficient OER electrocatalysts.
Biomimetic magnetofluorescent ferritin nanoclusters for magnetic resonance and fluorescence-dual modal imaging and targeted tumor therapy
Authors: Song Rongguang , Ruan Miaoliang , Dai Jian , Xue Wei
Published: January 2021

Multiple imaging by combining magnetic resonance (MR) and fluorescence imaging into a single nanosystem displays distinctive merits, which is desirable for precise in vivo imaging.
Multi-optical signal channel gold nanoclusters and their application in heavy metal ions sensing arrays
Authors: Gui Yunyun , Wang Yihe , He Chiyang , Tan Zhouqing , Gao Lingfeng , Li Wei , Bi Huiting
Published: January 2021

Novel multi-optical signal channel gold nanoclusters (MS-AuNCs) with CL and FL properties were designed and prepared by a one-pot method. Then the CL and FL spectra of MS-AuNCs were applied to the sensing array for heavy metal ion differentiation.
Analysis of armature winding open‐phase fault in multi‐phase annular brushless exciter at nuclear power plant
Authors: Chen Jianlin , Hao Liangliang , Wang Xiaoming , Guo Lixiong , Xiong Xin , Wei Yubang , Li Wenwu , Yang Deguang
Published: January 2021

The multi‐phase annular brushless exciter (MPABE) of nuclear power plants has suffered numerous armature winding open‐phase faults (AWOPF) in the field operation. In order to achieve reliable protection of the MPABE, its AWOPF is systematically studied through theoretical analysis, simulation calculation and model machine experiments. First, proceeding from the armature current waveform in normal operation and the influence of the AWOPF on it, the armature reaction magnetomotive force (MMF) is analysed deeply. Then, the theoretical analysis about the harmonic electromotive force (EMF) induced by armature reaction MMF on the field winding is presented, obtaining the harmonic characteristics of field current: the even‐order field harmonic currents increase obviously under the AWOPF. Finally, correlate experiments and simulations were performed on a customized experimental prototype. The experimental and simulation results are consistent and verify the conclusion of the theoretical analysis, which can serve as a theoretical basis for the monitoring and diagnosis method of the AWOPF in the MPABE.
Optical-to-NIR magnitude measurements of the Starlink LEO Darksat satellite and effectiveness of the darkening treatment
Authors: Tregloan-Reed J. , Otarola A. , Unda-Sanzana E. , Haeussler B. , Gaete F. , Colque J. P. , González-Fernández C. , Anais J. , Molina V. , González R. , Ortiz E. , Mieske S. , Brillant S. , Anderson J. P.
Published: January 2021

Aims. We aim to measure the Sloan r′, Sloan i′, J, and Ks magnitudes of Starlink’s STARLINK-1130 (Darksat) and STARLINK-1113 low Earth orbit (LEO) communication satellites and determine the effectiveness of the Darksat darkening treatment from the optical to the near-infrared (NIR).

Methods. Four observations of Starlink’s LEO communication satellites, Darksat and STARLINK-1113, were conducted on two nights with two telescopes. The Chakana 0.6 m telescope at the Ckoirama observatory (Chile) observed both satellites on 5 Mar. 2020 (UTC) and 7 Mar. 2020 (UTC) using a Sloan r′ and Sloan i′ filter, respectively. The ESO VISTA 4.1 m telescope with the VIRCAM instrument observed both satellites on 5 Mar. 2020 (UTC) and 7 Mar. 2020 (UTC) in the NIR J-band and Ks-band, respectively.

Results. The calibration, image processing, and analysis of the Darksat images give r ≈ 5.6 mag, i ≈ 5.0 mag, J ≈ 4.2 mag, and Ks ≈ 4.0 mag when scaled to a range of 550 km (airmass = 1) and corrected for the solar incidence and observer phase angles. In comparison, the STARLINK-1113 images give r ≈ 4.9 mag, i ≈ 4.4 mag, J ≈ 3.8 mag, and Ks ≈ 3.6 mag when corrected for range, solar incidence, and observer phase angles. The data and results presented in this work show that the special darkening coating used by Starlink for Darksat has darkened the Sloan r′ magnitude by 50%, Sloan i′ magnitude by 42%, NIR J magnitude by 32%, and NIR Ks magnitude by 28%.

Conclusions. The results show that both satellites increase in reflective brightness with increasing wavelength and that the effectiveness of the darkening treatment is reduced at longer wavelengths. This shows that the mitigation strategies being developed by Starlink and other LEO satellite operators need to take into account other wavelengths, not just the optical. This work highlights the continued importance of obtaining multi-wavelength observations of many different LEO satellites in order to characterise their reflective properties and to aid the community in developing impact simulations and developing mitigation tools.
Implementierung und formative Evaluation eines Gesundheitslotsen zur Beratung von Gesundheitsgästen in einem Kurort
Authors: Lukasczik Matthias , Wolf Hans-Dieter , Römling Lisa , Schenk Jana , Heusinger Hanna , Oette Frank , Thormann Sylvie , Wagner Matthias , Vogel Heiner
Published: January 2021

Ziel Konzeption, Umsetzung und formative Evaluation des Einsatzes eines Gesundheitslotsen für Gesundheitsgäste in einem Kurort.

Methodik Es wurde eine Bestandserhebung von örtlichen Gesundheitsanbietern durchgeführt und eine Datenbank erstellt. Zudem wurde eine nationale und internationale Literaturrecherche zum Konzept durchgeführt. Gesundheitsgäste wurden zu Erwartungen an einen Gesundheitslotsen und zum Informationsbedarf befragt. Im Zuge der Implementierung erfolgten eine fortlaufende schriftliche Beratungsdokumentation sowie eine Befragung von Kooperationspartnern zur Bewertung des Gesundheitslotsen als Schnittstelle innerhalb der lokalen Angebotsstruktur.

Ergebnisse Die Literaturrecherche ergab keine Hinweise auf vergleichbare Konzepte. Die erstellte Anbieterdatenbank wurde als Instrument zu Beratungen sowie zur Bewertung der örtlichen Angebotsstruktur genutzt. Die Vorab-Befragung von Gesundheitsgästen ergab, dass diese v. a. Wert auf eine neutrale und objektive Beratung legen. Die Beratungsdokumentation zeigte, dass 53% der Gäste, die eine Beratung in Anspruch genommen haben, älter als 65 Jahre sind. Der Aufenthalt wurde mehrheitlich als privat finanzierter Urlaub, ambulante Vorsorgeleistung oder stationäre Rehabilitation umgesetzt. Fragen zu Institutionen mit medizinischer Infrastruktur standen in den Beratungen im Vordergrund. Das ursprüngliche Tätigkeitsfeld des Gesundheitslotsen wurde im Laufe der Implementierung in Richtung eines stärkeren Fokus auf die Einbindung in den Positionierungsprozess im Gesundheitstourismus modifiziert. Die befragten Projektpartner bewerteten diese Neupositionierung positiv.

Schlussfolgerung Im Studienkontext konnte das Konzept erfolgreich umgesetzt werden. Die Neuausrichtung des Aufgabenprofils führte zu einer verbesserten strukturellen Verankerung des Gesundheitslotsen vor Ort. Durch die Erstellung eines Handlungsleitfadens soll die Dissemination des Konzepts gefördert werden.
Adoption of Robotic-Arm-Assisted Total Knee Arthroplasty Is Associated with Decreased Use of Articular Constraint and Manipulation under Anesthesia Compared to a Manual Approach
Authors: Zhang Jenny , Matzko Chelsea N. , Sawires Andrew , Ehiorobo Joseph O. , Mont Michael A. , Hepinstall Matthew S.
Published: January 2021

Haptic robotic-arm-assisted total knee arthroplasty (RATKA) seeks to leverage three-dimensional planning, intraoperative assessment of ligament laxity, and guided bone preparation to establish and achieve patient-specific targets for implant position. We sought to compare (1) operative details, (2) knee alignment, (3) recovery of knee function, and (4) complications during adoption of this technique to our experience with manual TKA. We compared 120 RATKAs performed between December 2016 and July 2018 to 120 consecutive manual TKAs performed between May 2015 and January 2017. Operative details, lengths of stay (LOS), and discharge dispositions were collected. Tibiofemoral angles, Knee Society Scores (KSS), and ranges of motion were assessed until 3 months postoperatively. Manipulations under anesthesia, complications, and reoperations were tabulated. Mean operative times were 22 minutes longer in RATKA (p < 0.001) for this early cohort, but decreased by 27 minutes (p < 0.001) from the first 25 RATKA cases to the last 25 RATKA cases. Less articular constraint was used to achieve stability in RATKA (93 vs. 55% cruciate-retaining, p < 0.001; 3 vs. 35% posterior stabilized (PS), p < 0.001; and 4 vs. 10% varus-valgus constrained, p_ = _0.127). RATKA had lower LOS (2.7 vs. 3.4 days, p < 0.001). Discharge dispositions, tibiofemoral angles, KSS, and knee flexion angles did not differ, but manipulations were less common in RATKAs (4 vs. 17%, p = 0.013). We observed less use of constraint, shorter LOS, and fewer manipulations under anesthesia in RATKA, with no increase in complications. Operative times were longer, particularly early in the learning curve, but improved with experience. All measured patient-centered outcomes were equivalent or favored the newer technique, suggesting that RATKA with patient-specific alignment targets does not compromise initial quality. Observed differences may relate to improved ligament balance or diminished need for ligament release.
Urology during COVID-19 Pandemic Crisis: A Systematic Review
Authors: Thapa Bikash Bikram , Shrestha Dhan , Bista Sanjeeb , Thapa Suresh , Niranjan Vikram
Published: January 2021

Background Coronavirus disease 2019 (COVID-19) has evolved as a pandemic of unimaginable magnitude. The health care system is facing a tremendous challenge to provide ethical and quality care. The transformation of the patient-based care to population-based care during the COVID-19 pandemic has raised ethical dilemma among urologists. Our objective is to explore the consensus in modified standard urology care, that can be adopted and applied during COVID-19 and similar pandemic.

Methods We adopted an exploratory study design using secondary data. The data were extracted from a web-based medical library using keywords “COVID-19,” “severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2),” and “urology.” We identify and extrapolate (screening, eligibility, and inclusion) the data using PRISMA protocol, and summarize pandemic standard urology care under four main themes: (1) general urology care, (2) choice of surgical modality, (3) triage, and (4) urology training.

Result We identified 63 academic papers related to our research question. The majority are expert opinions and perspectives on urology care. The common consensus is triage-based urology care and surgeries. Life or organ threatening conditions need immediate attention. Universal protective measures (personal protective equipment, safe operative environment) and protocol-based patient care are necessary to prevent and control SARS-CoV-2 infection. Conservation of the resources and its rational distribution provide an ethical basis for population-based health care during a pandemic. Informed decision making serves best to patients, families, and society during the public health crisis.

Conclusion COVID-19 pandemic tends to transform standard urology practice into crisis standard population-based care. The consensus in crisis is drawn from evolving pieces of medical evidence and public health ethics. The provision of urology care during a pandemic is based on the availability of resources; severity of the disease, consequences of deferment of service, and dynamics of the pandemic.
2.12 Asymmetric Catalysis of Radical Reactions
Authors: Subramaniann H. , Sibi M. P.
Published: January 2021

Synthetic methodologies based on radical chemistry are efficient and powerful tools for the construction of carbon–carbon and carbon–heteroatom bonds. This chapter highlights the significance of asymmetric catalysis in free-radical reactions. Several asymmetric catalytic principles, ranging from early chiral Lewis acid and organocatalytic activation to recent photoredox and transition-metal-based asymmetric catalytic systems, are discussed.
Chinese description generation of dual attention images based on multi-modal fusion
Authors: Lv Xiyun
Published: January 2021

In view of the lack of attention to image features in most of the current research on image Chinese description generation, the low quality of image details, and the low accuracy of generated language description, a multi-modal fusion dual attention image description generation model is proposed. The model uses the pre-trained VGG19 network to extract image features, LSTM extracts key information features of text, and combines image features and text features through attention stitching to obtain the attention weight of each spatial position of the image, and then input it into the LSTM language model Generate descriptive sentences. In the AI Challenger 2017 test set, the BLEU-1 and CIDEr scores of this algorithm can reach 71.2 and 106.1 respectively, which are better than baseline models based on a single attention structure, such as NIC, and perform manual observation and comparison of the effects of several models. The model can generate natural language descriptions that can better represent the details of the picture.
An Improved Quasi-Resonant Controller for Grid-Connected Inverter with LCL Filter
Authors: Huang Yuhe , Zheng Shousen , Qi Xinmei , He Laipei
Published: January 2021

Aiming at the problem of insufficient response speed of traditional quasi-resonant controllers in the application of grid-connected inverters with LCL filter, a novel hybrid controller which combines a quasi-proportional resonant controller and an integrator is proposed in this paper. Base on this controller, the stability, the parameter design and the digital time delay compensation of the system are analyzed and designed in detail. Finally, its effectiveness is experimentally verified at Matlab/Simulink. By comparing with the traditional control method, it leads to a conclusion that the novel hybrid controller can maintain the control accuracy while allowing the system have good dynamic performance.
The SEIR model of COVID-19 forecasting rates of infections in New York City
Authors: Zha Jiajing , Liu Xiangdong , Sui Minggang
Published: January 2021

We used SEIR mathematical models to simulate the spread of COVID-19 in New York City, selecting a period of time to estimate the total number of infections and to predict the date of the highest number of infections. We found that the cumulative number of people infected or infected and the proportion of those infected increased with the increase in infectivity; The peak of infectious diseases is brought forward with the decrease of infectiousness; The number of people, Ir
+ Iu
(prevalence), and the estimated peak of the disease occurred on April 25. At R_0, the regeneration number is much higher than 1, which is proportional to the infection rate. Since the infectiousness of unreported cases is not known, we can predict the outbreak under three different scenarios and get reasonable results.
Studies on the evaluation of college classroom teaching quality based on SVM multiclass classification algorithm
Authors: Wu Xinghui , Zhou Yuping , Xing Haihua
Published: January 2021

In order to improve the evaluation accuracy and efficiency of the quality of classroom teaching in colleges and universities, combined with the teaching process and evaluation system of colleges and universities, a multi-class classification algorithm is proposed, namely, the Distance binary tree support vector machine based on Euclidean distance (DBT-SVM) algorithm, and the algorithm is used to predict the quality evaluation of classroom teaching in colleges and universities. The algorithm uses the Euclidean distance of the center of the two nearest sample classes to influence the classification, so that the first isolated classes can be separated first. Experimentally, the algorithm can improve the efficiency and accuracy of classification and solve the problem of multi-class classification.
A New Way to Evaluate Products with Reviews: A Case Study of A Hair Dryer on Amazon Platform
Authors: Jin Xiting , Liu Xiangdong , Xiangsheng Zhan
Published: January 2021

The era of big data is coming. How to make effective use of users’ feedback information data is the key to success in various online industries. In order to help target enterprise enter the market, we build a comprehensive rating evaluation model that can evaluate the sales status, future development and contain comprehensive indicators. We firstly study the one-dimensional index. We adopt the method of correlation analysis to find the ripple effect of star rating. Then we use SPSS to draw scatter plots to analysis correlation between specific quality description and star rating level. We found through the research that “star rating”, “comment validity”, “positive and negative indicator in comments” and “member effect” are all informative for target enterprise to track, and will determine the market development of the product to a certain extent. We take advantage of the machine learning to turn the information in the text into quantifiable metrics and get polarity and subjectivity. Use NLTK for sentiment analysis of each comment to get negative, positive, neutral and compound value. Then use AHP to assign weight to the indicators wisely. With the comprehensive rating evaluation model that we build, we calculate the comprehensive rating value of all products in this industry and take the median as the benchmark value, then the products with the comprehensive rating value higher than the benchmark value can be regarded as successful products. We provide an accurate assessment. In order to effectively evaluate and predict the future sales trend of new products after their launch and effectively measure the increase and decrease of product market reputation, we establish a time-based measurement and prediction model based on Grey model theory. We can use the model to make comprehensive evaluation and effective prediction of the target company’s products. After inspection, our model can be effectively applied to different sales fields, which has great practical significance.
Analysis of Massive MIMO&NOMA of 5G and Future Prospects
Authors: Liu Yincheng
Published: January 2021

Since the 1970s, mobile communication has evolved from analog voice communication to a technology that can provide high-quality mobile broadband services today. The data rate of end users has reached several megabits per second, and the user experience has been continuously improved. In addition, with the increase of new mobile devices, the continuous growth of communication services and the continuous increase of network traffic, the existing wireless technology can no longer meet the needs of future communications. The 5th generation mobile communication system (5G) came into being, and its technological development is still in the exploratory stage. This article discusses the key technologies of 5G, massive MIMO (Multiple input multiple output) and NOMA (Non-orthogonal multiple access), briefly introduces their principles, and analyzes the advantages and potential research directions. Finally, this article looks forward to the development trend of 5G technology.
HelpCloud: Hierarchy Health Evaluation for Private Cloud
Authors: Liu Yiming , Xu Peng , Lin Yajian , Yu Qihang
Published: January 2021

Although the private cloud technology is developing rapidly, the operation and maintenance of private cloud are still too complicated for many non-IT enterprises. System health evaluation for private clouds is beneficial to reduce operation and maintenance complexity and workload. This paper aims to provide an easy-to-use method to evaluate a private cloud's system health. Firstly, we propose the Private Cloud Management Object Model (PCMOM). PCMOM uses a hierarchical architecture to organize a variety of entities in the private cloud. Secondly, based on PCMOM, Hierarchy health evaluation for the private Cloud (HelpCloud) Model is generated using the Analytic Hierarchy Process and D-S evidence theory. In the end, a set of tests verified the effectiveness of the HelpCloud model. Moreover, the management portal for the private cloud which integrates the HelpCloud model is designed and implemented. After several enterprises' trials, these enterprises recognized that using the HelpCloud model could simplify the private cloud's operation and maintenance.
Research on Dynamic Content Control Method in Virtual Projection
Authors: Xiu Yulin , Zhang Yue
Published: January 2021

With the rapid development of virtual projection technology, it has been widely used in art, stage design, cultural communication and other industries due to its unique characteristics of combining virtual with reality and its advantages of strong interactive immersion. In traditional stage design, the projection position and coordinates of virtual projection are fixed in advance, and actors must remember the projected coordinates of virtual image during performance, so as to accurately match the projection. This imposes great limitations on the performance of actors, and due to the complexity of the stage, it is difficult to achieve good interaction effects. Starting from the novel "dynamic" control technology in the virtual projection, this topic studies the intelligent control method of dynamic content in the projection. In the video projection process, FBX model is loaded dynamically, and the animation on the model is loaded and called dynamically.
The Independent Set Polynomials of a class of Graphs
Authors: Liu Man , Cai Jin , Zhuo-mo AN , Tian Shuang-liang
Published: January 2021

In this paper, a special graph is defined. According to the structural characteristics of the special graph

C

1
,
d

1
,
n

, the independent set polynomial of a special graph

I

(

C

1
,
d

1
,
n

;
x

)

is derived by using the properties and lemma of independent set polynomial of simple graph. The Merrifield-Simmons index of this kind of special graph

C

1
,
d

1
,
n

can be obtained.