bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deep Space Observations of Terrestrial Glitter
Authors: Kostinski Alexander , Marshak Alexander , Várnai Tamás 
Published: January 2021

AbstractDeep 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

AbstractThe 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

AbstractWe 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

AbstractThe 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

AbstractWhistlers 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

AbstractDry 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

AbstractAn 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

AbstractSurface 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

AbstractHow 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.
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

AbstractThe 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

Zusammenfassung
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

AbstractHaptic 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.