bluuebunny/crossref_metadata_2025 huggingface dataset:
Convergence and quasi-optimal cost of adaptive algorithms for nonlinear operators including iterative linearization and algebraic solver
Authors: Haberl Alexander , Praetorius Dirk , Schimanko Stefan , Vohralík Martin
Published: February 2021

We consider a second-order elliptic boundary value problem with strongly monotone and Lipschitz-continuous nonlinearity. We design and study its adaptive numerical approximation interconnecting a finite element discretization, the Banach–Picard linearization, and a contractive linear algebraic solver. In particular, we identify stopping criteria for the algebraic solver that on the one hand do not request an overly tight tolerance but on the other hand are sufficient for the inexact (perturbed) Banach–Picard linearization to remain contractive. Similarly, we identify suitable stopping criteria for the Banach–Picard iteration that leave an amount of linearization error that is not harmful for the residual a posteriori error estimate to steer reliably the adaptive mesh-refinement. For the resulting algorithm, we prove a contraction of the (doubly) inexact iterates after some amount of steps of mesh-refinement/linearization/algebraic solver, leading to its linear convergence. Moreover, for usual mesh-refinement rules, we also prove that the overall error decays at the optimal rate with respect to the number of elements (degrees of freedom) added with respect to the initial mesh. Finally, we prove that our fully adaptive algorithm drives the overall error down with the same optimal rate also with respect to the overall algorithmic cost expressed as the cumulated sum of the number of mesh elements over all mesh-refinement, linearization, and algebraic solver steps. Numerical experiments support these theoretical findings and illustrate the optimal overall algorithmic cost of the fully adaptive algorithm on several test cases.
Clinical characteristics and immunological abnormalities of Castleman disease complicated with autoimmune diseases
Authors: Sun Dao-Ping , Chen Wen-Ming , Wang Li , Wang Zhen , Liang Jin-Hua , Zhu Hua-Yuan , Fan Lei , Wu Yu-Jie , Xu Wei , Li Jian-Yong
Published: February 2021

Purpose

To explore the clinical features and immunological mechanisms of Castleman disease (CD) complicated with autoimmune diseases (AID).

Methods

We explored the prevalence and clinical manifestations of CD complicated with AID by reviewing clinical, pathological, and laboratory data of 40 CD patients retrospectively, and then explored abnormal immune mechanisms in the co-existence of the two entities by monitoring lymphocyte subsets in peripheral blood.

Results

Paraneoplastic pemphigus, autoimmune hemolytic anemia, Sjogren’s syndrome, myasthenia gravis, and psoriasis were found to be coexisted with CD in 9/40 (22.5%) patients with different sequence of onset. No bias in the clinical and histological type of CD was observed for the occurrence of AID. CD patients with AID were more likely to have skin and/or mucous membrane damage and pulmonary complications, and presented elevated erythrocyte sedimentation rate, hypergammaglobulinemia, and positive autoantibodies than those without AID (p < 0.05). Deregulated cellular and innate immune responses as indicated by decreased CD3+ T cells and increased natural killer cells were observed in peripheral blood of CD patients with AID (p < 0.05). UCD patients with AID were successfully treated with surgery and immunosuppressive therapy. MCD complicated by AID relieved with immunosuppressors, cytotoxic chemotherapy, and rituximab.

Conclusion

Systemic inflammation/immunological abnormalities and organ dysfunction were associated with the occurrence of AID in CD. Impairment of cellular and innate immunity may be a candidate etiology for the coexistence of the two entities.
The links between diabetes mellitus and amyotrophic lateral sclerosis
Authors: Vasta Rosario , D’Ovidio Fabrizio , Logroscino Giancarlo , Chiò Adriano
Published: February 2021

ALS etiology and prognostic factors are mostly unknown. Metabolic diseases and especially diabetes mellitus (DM) have been variously related to ALS. However, pieces of evidence have been variegated and often conflicting so far. This review aims to give an overview of recent contributions focusing on the relationship between DM and ALS. DM seems to reduce the risk of developing ALS if diagnosed at a younger age; conversely, when diagnosed at an older age, DM seems protective against ALS. Such a relationship was not confirmed in Asian countries where DM increases the risk of ALS independently of the age of onset. Interestingly, DM does not affect ALS prognosis, possibly weakening the potential causal relationship between the two diseases. However, since most studies are observational, it is difficult to state the exact nature of such a relationship and several hypotheses have been made. A recent study using Mendelian randomization suggested that DM is indeed protective against ALS in the European population. However, these analyses are not without limits and further evidence is needed. DM is usually the core of a larger metabolic syndrome. Thus, other metabolic changes such as dyslipidemia, body mass index, and cardiovascular diseases should be collectively considered. Finally, hypermetabolism usually found in ALS patients should be considered too since all these metabolic changes could be compensation (or the cause) of the higher energy expenditure.
Leukocyte Telomere Length in Patients with Multiple Sclerosis and Its Association with Clinical Phenotypes
Authors: Hecker Michael , Fitzner Brit , Jäger Kathrin , Bühring Jan , Schwartz Margit , Hartmann Alexander , Walter Michael , Zettl Uwe Klaus
Published: February 2021

Aging is a significant factor influencing the course of multiple sclerosis (MS). Accelerated telomere attrition is an indicator of premature biological aging and a potential contributor to various chronic diseases, including neurological disorders. However, there is currently a lack of studies focusing on telomere lengths in patients with MS. We measured the average leukocyte telomere length (LTL) in biobanked DNA samples of 40 relapsing-remitting MS patients (RRMS), 20 primary progressive MS patients (PPMS), and 60 healthy controls using a multiplex quantitative polymerase chain reaction method. Changes in LTL over a period of >10 years were evaluated in a subset of 10 patients. Association analyses of baseline LTL with the long-term clinical profiles of the patients were performed using inferential statistical tests and regression models adjusted for age and sex. The cross-sectional analysis revealed that the RRMS group was characterized by a significantly shorter relative LTL, on average, as compared to the PPMS group and controls. Shorter telomeres at baseline were also associated with a higher conversion rate from RRMS to secondary progressive MS (SPMS) in the 10-year follow-up. The LTL decrease over time was similar in RRMS patients and PPMS patients in the longitudinal analysis. Our data suggest a possible contributory role of accelerated telomere shortening in the pathobiology of MS. The interplay between disease-related immune system alterations, immunosenescence, and telomere dynamics deserves further investigation. New insights into the mechanisms of disease might be obtained, e.g., by exploring the distribution of telomere lengths in specific blood cell populations.
Freeze-drying and hot-pressing strategy to embed two-dimensional Ti0.87O2 monolayers in commercial polypropylene films with enhanced dielectric properties
Authors: Tian Wenchao , Yan Fei , Cai Cailing , Wu Zeyi , Zhang Chenchen , Yin Ting , Lao Sijia , Hu Linfeng
Published: February 2021

The dielectric capacitor has been widely used in advanced electronic and electrical power systems due to its capability of ultrafast charging-discharging and ultrahigh power density. Nevertheless, its energy density is still limited by the low dielectric constant(≈ 2.2) of the commercial dielectric polypropylene (PP). The conventional enhancement strategy by embedding inorganic fillers in PP matrix is still difficult and challenging due to that PP hardly dissolves in any inorganic/organic solvent. In this work, we develop a new strategy including freeze-drying, surface functionalization, and hot-pressing to incorporate Ti0.87O2 monolayers in PP film. A series of uniform composited Ti0.87O2@PP film has been successfully fabricated with Ti0.87O2 content range of 0–15 wt%. The maximum dielectric constant of the as-prepared Ti0.87O2@PP film is 3.27 when the Ti0.87O2 content is 9 wt%, which is about 1.5 times higher than that of pure PP. Our study provides a feasible strategy to embed two-dimensional material into commercial PP thin-film with superior dielectric performance for practical application.
Characteristics of CFRP/PU foam and GFRP/PU sandwich beams having initial debond between facesheet and core
Authors: Dhaliwal Gurpinder Singh
Published: February 2021

In the present investigation, we present, the flexural characteristics of carbon fiber reinforced polymer/polyurethane foam and glass fiber reinforced polymer/polyurethane foam sandwich beams having partial debonding between facesheet and core that acts interfacial degradation and hinders the load transfer between facesheets and core. An initial pre-crack between core and face sheet is created by placing a Teflon sheet at the interface on one end of the beams during the manufacturing of sandwich beams. A comparative analysis is carried out to study the effect of using CFRP and Eglass prepregs as face sheet material on such sandwich beams. The flexural behavior of GFRP/PU sandwich beams having initial debond is characterized and analyzed under both three- and four-point loadings. Lastly, the effect of varying the support span length on the flexural response of CFRP/PU sandwich beam having initial debond is also investigated. It was found that the degraded sandwich beams having woven CFRP facesheets have slightly higher stiffness and peak load level as compared to the sandwich beam having cross ply GFRP facesheets. GFRP/PU foam sandwich beam showed higher ductile behavior prior to progressive failure of the sandwich beam. It was observed that the crack tip of the implanted interfacial debond acts as a medium to trigger the interfacial damage followed by the shear failure of the core due to the progression of the initial crack into the core.
An Examination of Empathy and Interpersonal Dominance in BDSM Practitioners
Authors: Jansen Kate L. , Fried Adam L. , Chamberlain Jared
Published: February 2021

Background

Recent research has indicated that participation in BDSM (bondage-discipline, dominance-submission, and/or sadism-masochism) is not associated with psychological distress or psychopathology but that sexual roles may be associated with personality characteristics, specifically interpersonal dominance and empathy.

Aim

The present study examined potential differences between those who identify as dominant, switch, and submissive on interpersonal dominance and empathy.

Methods

Individuals who identified as members of the BDSM community were recruited online via a social networking site.

Main Outcome Measures

Self-reported demographic variables, the Personality Assessment Inventory, Dominance subscale, and the Interpersonal Reactivity Index Empathic Concern subscale.

RESULTS

Participants were well distributed across sexual roles (n = 279; 25.4% dominant, 38% submissive, 36.6% switch), identified as primarily female (59.5%), primarily heterosexual (53.4%), and the most common age group was 25-34 years (27.2%). BDSM role was associated with scores on the Dominance subscale; dominant BDSM practitioners scored significantly higher on the Dominance scale than switches, who in turn scored significantly higher than submissives (dominant mean [M] = 61.44, standard deviation [SD] = 8.26; switch M = 53.99, SD = 11.18, P < .01; submissive M = 49.41, SD = 11.46, P < .01). There were no differences on the measure of empathy between dominant, submissive, and switch BDSM practitioners. On average, individuals who identified as submissives and switches scored in the average range on the Dominance scale compared with the normative sample, and individuals who identified as dominants scored higher but not in the markedly elevated range.

Clinical Implications

The study provides information on the relationship between interpersonal dominance as a personality trait and dominance as a sexual role and has implications for reducing stigma related to these practices.

Strengths and Limitations

The study contributes to the growing literature suggesting that while BDSM roles may correspond with specific personality characteristics, they are not indicative of personalities significantly different than the general population’s. The study also included individuals who identified as switch, a group often excluded from quantitative research in the BDSM community. The sample was, however, recruited exclusively online, and findings may not be applicable to all BDSM practitioners.

CONCLUSION

These findings suggest that there are no differences in empathy between BDSM practitioner roles, and although there are differences in interpersonal dominance, these characteristics are not likely to be prominent in individuals’ everyday interactions.
Charcoal evidence for environmental change ca. 3.5 ka and its influence on ancient people in the West Liao River Basin of northeastern China
Authors: Jia Xin , Wang Shuzhi , Sun Yonggang , Li Yiyin , Jiao Yanjing , Zhao Zhijun , Lee Harry F.
Published: February 2021

Fossil charcoals from archaeological sites provide direct evidence for the relationship between environmental change and ancient peoples’ livelihoods in the past. Our identification of 5811 fossil charcoal fragments from 84 samples suggested temperate deciduous and mixed conifer-broadleaved forests as the dominant vegetation at the Erdaojingzi site in northeastern China ca. 3500 cal yr BP; the major representative taxa were Quercus, Pinus, and Ulmus. Four woody plants probably supplied humans with food resources at the Erdaojingzi site, including Quercus, Ulmus, Amygdalus/Armeniaca, and Ziziphus. The nuts of Quercus were utilized as staple foods because of their rich starch content. The leaves of Ulmus may have been used by humans because of their massive dietary fibre. Amygdalus/Armeniaca and Ziziphus probably provided fruits for humans. Based on the coexistence approach (CA) used on the fossil charcoals, we found that the MAT anomaly was 7.9 ± 5.9°C at ca. 3500 cal yr BP, which is almost the same as the modern one (7.8°C), while the MAP was halved from 772 ± 301 mm at ca. 3500 cal yr BP to 370 mm currently. The wet climate might have facilitated significant development of rain-fed agriculture, promoted the emergence of large settlements, and eventually facilitated the birth of civilization.
Stably inherited transfer of the bacterial symbiont Candidatus Erwinia dacicola from wild olive fruit flies Bactrocera oleae to a laboratory strain
Authors: Livadaras Ioannis , Koidou Venetia , Pitsili Eugenia , Moustaka Julietta , Vontas John , Siden-Kiamos Inga
Published: February 2021

The olive fruit fly, Bactrocera oleae, the most serious pest of olives, requires the endosymbiotic bacteria Candidatus Erwinia dacicola in order to complete its development in unripe green olives. Hence a better understanding of the symbiosis of Ca. E. dacicola and its insect host may lead to new strategies for reduction of B. oleae and thus minimize its economic impact on olive production. Studies of this symbiosis are hampered as the bacterium cannot be grown in vitro and the established B. oleae laboratory populations, raised on artificial diets, are devoid of this bacterium. Here, we sought to develop a method to transfer the bacteria from wild samples to laboratory populations. We tested several strategies. Cohabitation of flies from the field with the laboratory line did not result in a stable transfer of bacteria. We provided the bacteria directly to the egg and also in the food of the larvae but neither approach was successful. However, a robust method for transfer of Ca. E. dacicola from wild larvae or adults to uninfected flies by transplantation to females was established. Single female lines were set up and the bacteria were successfully transmitted for at least three generations. These results open up the possibilities to study the interaction between the symbiont and the host under controlled conditions, in view of both understanding the molecular underpinnings of an exciting, unique in nature symbiotic relationship, as well as developing novel, innovative control approaches.
FURTHER RESULTS ON STOCHASTIC ORDERINGS AND AGING CLASSES IN SYSTEMS WITH AGE REPLACEMENT
Authors: Corujo Josué , Valdés José E.
Published: February 2021

Reliability properties associated with the classic models of systems with age replacement have been a usual topic of research. Most previous works have checked the aging properties of the lifetime of the working units using stochastic comparisons among the systems with age replacement at different times. However, from a practical point of view, it would also be interesting to deduce to which aging classes the lifetime of the system belongs, making use of the aging properties of the lifetime of its working units. The first part of this article deals with this problem. Further along, stochastic orderings are established between the systems with replacement at the same time using several stochastic comparisons among the lifetimes of their working units. In addition, the lifetimes of two systems with age replacement are compared as well. This is performed assuming stochastic orderings between the number of replacement until failure, and the lifetimes of their working units conditioned to be less or equal than the replacement time. Similar comparisons are accomplished considering two systems with age replacement where the replacements occur at a random time. Illustrative examples are presented throughout the paper.
Small Signals: Comprehending the Australian Microlithic as Public Signalling
Authors: Hiscock Peter
Published: February 2021

Signalling is a critical capacity in modern human cultures but it has often been difficult to identify and understand on lithic artefacts from pre-literate contexts. Often archaeologists have minimized the signalling role of lithic tools by arguing for strong form-function relationships that constrained signalling or else imposed ethnographic information on the archaeological patterns with the assumption they assist in defining the signalling carried out in prehistory. In this paper I present a case study for which it can be shown that function does not correlate with form and that the technology fell out of use 1000–1500 years ago. This means that neither presumptions of continuity in social practice nor reference to tool use provide strong explanations for the size, shape standardization and regional differentiation of Australian microliths. Sender-receiver signalling theory is harnessed to motivate a new synthesis of these microliths, and I demonstrate that not only were these artefacts probably key objects used in public signalling but also that sender-receiver frameworks enable us to infer details about the operation of the signalling system.
Material Scientists: Learning the Importance of Colour and Brightness from Lithic Practitioners
Authors: Weedman Arthur Kathryn
Published: February 2021

In this paper, I present Ethiopia's Boreda lithic practitioners’ perception of knapping stone as a living vital being and how it informs their selection of colourful stones and transmission of knowledge to apprentices. In particular, lithic practitioners select stones which are perceived to exhibit evidence of their vitality in the form of light and choose particular colours of stone for their association with transformation and community identity. Furthermore, elders use these attributes of stone to assist apprentices in learning to identify good-quality parent material, ensuring longevity of a tool's life.
Optimising image-guidance frequency for patients treated with volumetric-modulated arc therapy for pelvic cancer
Authors: Wongke Thunyarat , Nobnop Wannapha , Tharavichitkul Ekkasit
Published: February 2021

Aim:

To determine the feasibility of non-daily image-guided radiotherapy (RT) with volumetric-modulated arc therapy for pelvic cancer.

Methods:

Daily cone beam computed tomography (CBCT) images data of 21 patients (542 fractions) with pelvic cancer were used to simulate 5 non-daily imaging (DL) protocols (Alternate day: AD, First 5 + Weekly: FF+WL, Weekly: WL, First 5 fractions: FF and Alternate week: AW protocol). The residual errors in the lateral (X), longitudinal (Y), and vertical (Z) directions and 3D vector shifts of each non-DL protocol were explored. The planning target volume (PTV) margins were calculated using the van Herk’s formula according to population systematic and random error. Finally, the average time of each process from the start to stop of the treatment was used to calculate the number of patients treated per day to assess the treatment delivery capacity for different imaging protocols.

Results:

The 3D vector shift for the FF+WL protocol produced the greatest proportion of residual error ≤ 0·5 cm and showed the smallest random error in all three directions. However, the FF protocol produced the greatest proportion of residual error > 0·5 cm and revealed the largest magnitudes of systematic error in all three directions. Only the AD protocol can explore the PTV margin of less than 0·5 cm in all three directions. The AW protocol showed the maximum capacity of the treatment delivery, showed the highest number of patients treated per day. In contrast, the AW protocol also affects the treatment accuracy, showed the large residual error and PTV margin.

Findings:

Reducing the frequency of image-guided RT results in a high residual error. Non-daily image-guided RT strategies for pelvic irradiation should be applied for margins more than 0·5 cm. The number of patients treated per day, residual error and PTV margin are information to determine non-daily protocol applications that balance treatment delivery capacity and treatment accuracy.
THE SHAKESPEARE CONNECTION: BEETHOVEN'S STRING QUARTET OP. 18 NO. 1 AND THE VIENNA HAUSTHEATER
Authors: VAN DER ZANDEN JOS
Published: February 2021

The ‘Amenda anecdote’ from 1856 associates the second movement of Beethoven's String Quartet Op. 18 No. 1 (Adagio affettuoso ed appassionato) with the vault scene of Shakespeare's Romeo and Juliet. Sketchbook jottings by Beethoven from 1799, in French, confirm that such a link really existed. The question of what incited him to represent in his music elements of Shakepeare has not been settled to any satisfaction. It seems unlikely that Beethoven read a French version of the play. Nor can a public theatrical or operatic staging have been the stimulus, for the original vault scene was not allowed to be performed by the authorities. This study approaches the Shakespeare connection from the perspective of a cultural practice that has received limited attention in the literature, that of Viennese Haustheater. A performance of the vault scene in this context, it is argued, informed Beethoven's quartet movement. The most crucial piece of evidence are the memoirs of Caroline Pichler, which mention a tableau given at her parents’ house at the end of eighteenth century. One of the claims of the study is that Beethoven's Shakespeare connection was a one-time digression from normal practice, and that it is thus hazardous to draw this particular event into a wider hermeneutic debate.
The Benefits of Continuous Local Regression for Quantifying Global Warming
Authors: Clarke David C. , Richardson Mark
Published: February 2021

Change in global mean surface temperature (ΔGMST), based on a blend of land air and ocean water temperatures, is a widely cited climate change indicator that informs the Paris Agreement goal to limit global warming since preindustrial to “well below” 2°C. Assessment of current ΔGMST enables determination of remaining target‐consistent warming and therefore a relevant remaining carbon budget. In recent IPCC reports, ΔGMST was estimated via linear regression or differences between decade‐plus period means. We propose nonlinear continuous local regression (LOESS) using ±20 year windows to derive ΔGMST across all periods of interest. Using the three observational GMST data sets with almost complete interpolated spatial coverage since the 1950s, we evaluate 1850–1900 to 2019 ΔGMST as 1.14°C with a likely (17%–83%) range of 1.05°C–1.25°C, based on combined statistical and observational uncertainty, compared with linear regression of 1.05°C over 1880–2019. Performance tests in observational data sets and two model large ensembles demonstrate that LOESS, like period mean differences, is unbiased. However, LOESS also provides a statistical uncertainty estimate and gives warming through 2019, rather than the 1850–1900 to 2010–2019 period mean difference centered at the end of 2014. We derive historical global near‐surface air temperature change (ΔGSAT), using a subset of CMIP6 climate models to estimate the adjustment required to account for the difference between ocean water and ocean air temperatures. We find ΔGSAT of 1.21°C (1.11°C–1.32°C) and calculate remaining carbon budgets. We argue that continuous nonlinear trend estimation offers substantial advantages for assessment of long‐term observational ΔGMST.
Will Individual Actions Do the Trick? Comparing Climate Change Mitigation Through Geoengineering Versus Reduced Vehicle Emissions
Authors: Murray Emily G. , DiGiorgio Andrea L.
Published: February 2021

Geoengineering is the focus of a large debate over potential solutions to climate change. However, in the midst of geoengineering and other large‐scale proposals, such as reducing emissions at an industrial level, the role of individual actions to reduce emissions is often overlooked. Given the current and fast‐paced changes we have seen as emissions are reduced by COVID‐19 social distancing strategies, it is time to re‐examine the impact that individual actions can have. This paper considers how one individual action (reducing carbon dioxide emissions from gasoline‐fueled private vehicles), when adopted at a global scale, may have an effect that is comparable to the effects of geoengineering. This paper also argues that the role of geoengineering as a safeguard against climate change may be encouraging complacency and reducing motivation for individual action.
Lithosphere Destabilization and Small‐Scale Convection Constrained From Geophysical Data and Analogical Models
Authors: Adam C. , Vidal V. , Pandit B. , Davaille A. , Kempton P. D.
Published: February 2021

The destabilization of oceanic lithosphere by small scale convection at its base is important for providing a holistic picture of mantle/lithosphere coupling. We use three highly resolved tomography models to characterize the base of the oceanic lithosphere in the Pacific Ocean. Regions associated with abnormally thick lithosphere are associated with seafloor older than 100 Ma and are elongated parallel to the direction of present‐day Pacific plate motion. They are correlated with bathymetric lows and negative geoid anomalies (for l = 10–39 and l = 14–39), which can be accounted for by dynamic topography. They do not correlate with volcanic features. We interpret these regions of thickened lithosphere as evidence for sites of lithospheric instabilities where denser lithosphere detaches and sinks into the underlying mantle. To understand the phenomena at the origin of these lithospheric “drips,” we performed laboratory experiments. Fluids with different properties are heated from one side to generate a large‐scale convection and cooled from the top. This configuration results in the generation of small‐scale convection at the base of the upper cold thermal boundary layer. The experimental results show the existence of two possible structures: instabilities organized into longitudinal rolls, aligned in the direction of the large‐scale motion and 3D, time‐dependent cold plumes that drip from the base of the lithosphere and are sheared away by the large‐scale flow. The 3D plume morphology is similar to what we observe in tomography models. This provides insights into the phenomenology at the origin of the lithospheric drips observed in the geophysical data.
Upper Mantle Anisotropic Shear Velocity Structure at the Equatorial Mid‐Atlantic Ridge Constrained by Rayleigh Wave Group Velocity Analysis From the PI‐LAB Experiment
Authors: Saikia Utpal , Rychert Catherine , Harmon Nicholas , Kendall J. M.
Published: February 2021

The evolution of ocean lithosphere and asthenosphere are fundamental to plate tectonics, yet high resolution imaging is rare. We present shear wave velocity and azimuthal anisotropy models for the upper mantle from Rayleigh wave group velocities from local earthquake and ambient noise at 15–40‐s period recorded by the Passive Imaging of the Lithosphere Asthenosphere Boundary experiment at the equatorial Mid‐Atlantic Ridge covering 0–80‐Myr‐old seafloor. We find slow velocities along the ridge, with faster velocities beneath older seafloor. We image a fast lid (25–30‐km thick) beneath the ridge that increases to 50–60 km beneath older seafloor. Punctuated, ∼100 km wide low velocity anomalies exist off‐axis. There are multiple layers of azimuthal anisotropy, including (i) a lithosphere (20–40 km depth) characterized by strong anisotropy (4.0%–7.0 %) with fast‐axes that rotate from ridge subparallel toward the absolute plate motion/spreading direction at distances >60 km from the ridge, and (ii) weak anisotropy (1.0%–2.0%) at >40 km depth. Our results are consistent with conductive cooling of lithosphere, although with some complexities. Thickened lithosphere beneath the ridge supports lateral conductive cooling beneath slow‐spreading centers. Undulations in lithospheric thickness and slow asthenospheric velocities are consistent with small scale convection and/or partial melt. Lithospheric anisotropy can be explained by vertical flow and a contribution from either fluid or mineral filled cracks organized melt beneath the ridge and plate motion induced strain off axis. Deep azimuthal anisotropy is suggestive of upwelling beneath the ridge and three‐dimensional flow possibly caused by small scale convection off‐axis.
Mapping and Modeling Sources of Natural Remanent Magnetization in the Microcline–Sillimanite Gneiss, Northwest Adirondack Mountains: Implications for Crustal Magnetism
Authors: Pastore Z. , McEnroe S. A. , Church N. S. , Oda H.
Published: February 2021

Distinct crustal remanent magnetic anomalies are a strong indicator of rocks with stable natural remanent magnetization (NRM) carriers. The latter are able to store information on the history of a rock over long geological periods, and can therefore be used for a variety of applications in the field of paleomagnetism and rock magnetism. Typically, paleomagnetic and rock‐magnetic studies rely on rocks bulk magnetic properties. With the advent of high‐resolution magnetometric scanning techniques, it is now possible to map magnetic sources at the mineral scale, identify the different magnetic carriers, and analyze the effect of geometry, microstructures, and composition on their magnetic response. We investigate the stability of discrete remanent magnetization sources of a microcline–sillimanite gneiss sample from Russell Belt with a strong NRM, by scanning the sample before, and after alternating field demagnetization to 100 mT. We quantified changes in the magnetization intensity and direction by inverting the magnetic scan data. Here, we confirm that the exsolved titanohematite with ilmenite lamellae is the major source of magnetization, and the coexisting multidomain hematite grains contribute little to the NRM, or the magnetic anomalies. The microstructures in the titanohematite control local magnetic properties at the mineral scale. Magnetic modeling results suggest a consistent average magnetization direction before and after demagnetization at both the grain and thin section scale, with a decrease in the magnetization intensity of ≈30%. Results are consistent with previous bulk magnetic measurements and the likelihood to use high‐resolution magnetometric techniques in future magnetic studies is high.
No Yangtze River Prior to the Late Miocene: Evidence From Detrital Muscovite and K‐Feldspar40Ar/39Ar Geochronology
Authors: Sun Xilin , Tian Yuntao , Kuiper K.F. , Li Chang’an , Zhang Zengjie , Wijbrans J.R.
Published: February 2021

The Yangtze River is the largest river in Asia and its age and evolution has been the subject of debate for more than one century. Here, we applied a combination of detrital muscovite and K‐feldspar40Ar/39Ar dating on a set of samples from late Cenozoic Nanjing fluvial gravel sediments (overlain by basalt with ages of ∼22.9 and ∼10.3 Ma) distributed along the lower Yangtze River to trace the late Cenozoic Yangtze drainage. It is found that the characteristic Cenozoic muscovite and K‐feldspar age signals of the upper Yangtze are absent in the gravel sediments, indicating that the upper Yangtze did not supply sediment to the lower Yangtze before at least late Miocene time. These results do not support a prelate Miocene birth of the Yangtze River, but favor an alternative model highlighting later integration of the upper Yangtze into the mid‐lower reaches to form the current Yangtze drainage system.
Use of Neural Networks for Stable, Accurate and Physically Consistent Parameterization of Subgrid Atmospheric Processes With Good Performance at Reduced Precision
Authors: Yuval Janni , O'Gorman Paul A. , Hill Chris N.
Published: February 2021

A promising approach to improve climate‐model simulations is to replace traditional subgrid parameterizations based on simplified physical models by machine learning algorithms that are data‐driven. However, neural networks (NNs) often lead to instabilities and climate drift when coupled to an atmospheric model. Here, we learn an NN parameterization from a high‐resolution atmospheric simulation in an idealized domain by accurately calculating subgrid terms through coarse graining. The NN parameterization has a structure that ensures physical constraints are respected, such as by predicting subgrid fluxes instead of tendencies. The NN parameterization leads to stable simulations that replicate the climate of the high‐resolution simulation with similar accuracy to a successful random‐forest parameterization while needing far less memory. We find that the simulations are stable for different horizontal resolutions and a variety of NN architectures, and that an NN with substantially reduced numerical precision could decrease computational costs without affecting the quality of simulations.
Metocean Modulators of the First Recorded South Atlantic Hurricane: Catarina
Authors: Lauton Gustavo , Marta‐Almeida Martinho , S. Dorfschäfer Geoff , A. D. Lentini Carlos
Published: February 2021

In March 2004, the first‐ever documented South Atlantic Hurricane, Catarina, made landfall in southern Brazil. Here, we apply the genesis potential index (GPI) to give a quantitative diagnostic of the contribution of the environmental factors known to be linked to tropical cyclogenesis on Catarina's modulation. The results indicate two regions of large positive GPI anomalies: where Catarina (1) developed subtropical cyclone structure and underwent tropical transition, and (2) acquired hurricane status. We also examine the ocean's potential to sustain tropical cyclone intensification through the ocean heat content (OHC). Although some areas of positive OHC anomalies may have indicated conditions favorable to cyclogenesis, it was not sufficient to explain the main stages of Catarina's development. On the other hand, the GPI in March 2004 was the highest among March of all years (1990–2019), suggesting that this may be a valid index for obtaining a threshold for tropical cyclogenesis in south/southeastern Brazil.
Orographic Effect on Extreme Precipitation Statistics Peaks at Hourly Time Scales
Authors: Marra Francesco , Armon Moshe , Borga Marco , Morin Efrat
Published: February 2021

Orographic impact on extreme subdaily precipitation is critical for risk management but remains insufficiently understood due to complicated atmosphere‐orography interactions and large uncertainties. We investigate the problem adopting a framework able to reduce uncertainties and isolate the systematic interaction of Mediterranean cyclones with a regular orographic barrier. The average decrease with elevation reported for hourly extremes is found enhanced at subhourly durations. Tail heaviness of 10‐min intensities is negligibly affected by orography, suggesting self‐similarity of the distributions at the convective scale. Orography decreases the tail heaviness at longer durations, with a maximum impact around hourly scales. These observations are explained by an orographically induced redistribution of precipitation toward stratiform‐like processes, and by the succession of convective cores in multihour extremes. Our results imply a breaking of scale‐invariance at subhourly durations, with important implications for natural hazards management in mountainous areas.
Widespread Tissintite in Strongly Shock‐Lithified Lunar Regolith Breccias
Authors: Zhang Ai‐Cheng , Jiang Qin‐Ting , Tomioka Naotaka , Guo Yan‐Jun , Chen Jia‐Ni , Li Yang , Sakamoto Naoya , Yurimoto Hisayoshi
Published: February 2021

Shock‐lithification is a fundamental process of making rocks from fine‐grained and porous regoliths on the surface of the Moon. Previous investigations have constrained potential shock pressures during shock‐lithification based on experimental and numerical simulations. However, pressure and temperature conditions during shock‐lithification have not been directly inferred from natural lunar breccias. Here, we report the discovery of widespread tissintite in strongly shock‐lithified lunar meteorites, accompanied occasionally by Si‐rich corundum and coesite. The coexistence of tissintite and coesite and the absence of stishovite in molten regions indicate a shock pressure of 4–8 GPa, which might be the pressure boundary between weak and strong shock‐lithification. Meanwhile, the presence of Si‐rich corundum imposes a temperature constraint of ∼2,300 K for the intergranular melts. This temperature constraint has profound significance for interpreting the behaviors of volatile and moderately volatile elements and remanent magnetization records during strongly shock‐lithification of lunar breccias.
Second‐Harmonic Generation of Electromagnetic Emissions in a Magnetized Plasma: Kinetic Theory Approach
Authors: Yu Xiongdong , Yuan Zhigang , Xue Zuxiang
Published: February 2021

Second harmonics have been observed in various magnetospheric waves. Although particle simulations are able to produce the similar features as reported in satellite observations, the exact physical mechanism for the generation of second harmonics remains uncovered yet. In this letter, we first give wave equations describing the fundamental and second harmonics via multiscale analysis. Then, we apply a kinetic theory approach to obtain the conductivity tensor, nonlinear current density, and the necessary conditions for the second harmonic generation of electromagnetic emissions in a magnetized plasma. To verify our theoretical results, we also perform hybrid simulations to study the second harmonic generation of electromagnetic ion cyclotron waves for three cases in which the second harmonic deviates from the inherent modes by different degrees. Our results suggest the important role of the linear dispersion relation in the second‐harmonic generation.
A Large‐Scale Analysis of Pockets of Open Cells and Their Radiative Impact
Authors: Watson‐Parris D. , Sutherland S. A. , Christensen M. W. , Eastman R. , Stier P.
Published: February 2021

Pockets of open cells sometimes form within closed‐cell stratocumulus cloud decks but little is known about their statistical properties or prevalence. A convolutional neural network was used to detect occurrences of pockets of open cells (POCs). Trained on a small hand‐logged data set and applied to 13 years of satellite imagery the neural network is able to classify 8,491 POCs. This extensive database allows the first robust analysis of the spatial and temporal prevalence of these phenomena, as well as a detailed analysis of their micro‐physical properties. We find a large (30%) increase in cloud effective radius inside POCs as compared to their surroundings and similarly large (20%) decrease in cloud fraction. This also allows their global radiative effect to be determined. Using simple radiative approximations we find that the instantaneous global annual mean top‐of‐atmosphere perturbation by all POCs is only 0.01 W/m2.
e‐POP Observations of Suprathermal Electron Bursts in the Ionospheric Alfvén Resonator
Authors: Wu J. , Knudsen D. J. , Shen Y. , Gillies D. M.
Published: February 2021

Utilizing the suprathermal electron imager onboard the e‐POP satellite, we performed a statistical study of groups of repetitive suprathermal electron bursts (STEBs) with 52 events (each with ≥3 STEBs) during 21 e‐POP orbits. The STEBs are observed on both the day side and night side, and within a wide range of geomagnetic latitudes, from 64° to 78°. We interpret these data as temporally varying signatures; we suggest the repetition is due to the ionospheric Alfvén resonator (IAR), since the statistical time separation of adjacent STEBs in the satellite frame is 0.5–1.5 s, which is consistent with the characteristic period of the IAR. Furthermore, the STEBs are associated with low‐frequency magnetic field perturbations. The statistical occurrence of repetitive STEBs shows a preference toward postnoon and midnight sectors at high magnetic latitudes. We also present one example event of four successive STEBs associated with auroral rays in conjugate imagery. The repetition period of STEBs is similar to the oscillation period of magnetic fields observed by Enhanced Polar Outflow Probe (e‐POP). One of the STEBs in an example event exhibits “normal” dispersion (high energy particles with field‐aligned pitch angle arriving first) and the adjacent STEB exhibits “inverse” dispersion (low energy particles with broad pitch angles arriving first). With a test particle simulation, we propose one possible explanation of inverse dispersion in terms of a suprathermal electron population and a downward‐propagating parallel electric field.
Conjugate Properties of Magnetospheric Pc5 Waves: Antarctica‐Greenland Comparison
Authors: Pilipenko Vyacheslav A. , Martines‐Bedenko Valery A. , Coyle Shane , Fedorov Evgeny N. , Hartinger Michael D. , Engebretson Mark J. , Edwards Thom R.
Published: February 2021

An electric circuit analogy for magnetosphere‐ionosphere current systems has two extremes for their driver: a current generator and voltage generator. In the case of a magnetospheric current generator the ground magnetic effect must be nearly the same under low‐conductivity or high‐conductivity ionospheres, whereas in the case of a voltage generator the magnetic response must be larger under a high‐conductivity ionosphere. Theoretical consideration of the field‐aligned current generation by a magnetospheric driver within the framework of the magnetosphere “plasma box” model with asymmetric ionospheres showed that excitation of resonant Alfvenic oscillations should correspond rather to a current generator regime. The asymmetry of Pc5 waves (frequencies about several mHz) recorded at conjugate magnetometers in Greenland and Antarctica has been analyzed from the viewpoint of the voltage/current generator dichotomy. We have selected Pc5 events under contrasting ionospheric conditions, during summer and winter. For resonant frequencies, we have plotted the latitudinal profiles of spectral power and compared the amplitudes of spatial maxima in opposite hemispheres. Along the same profile, latitudinal dependences of the ionospheric height‐integrated conductivities have been reconstructed with the use of the OVATION‐prime (OP) and solar illumination models. During both winter and summer events, the amplitudes of the spectral power peak in Greenland and Antarctica have been found to be about the same, though the OP model predicts a contrast between ionospheric conductivities of 5–10 times. Thus, the interhemispheric properties of Pc5 waves correspond to the current generator regime, as predicted by the magnetospheric plasma box model.
The Influence of Magnetic Field Topology and Orientation on the Distribution of Thermal Electrons in the Martian Magnetotail
Authors: Nauth Murti , Fowler Christopher M. , Andersson Laila , DiBraccio Gina A. , Xu Shaosui , Weber Tristan , Mitchell David
Published: February 2021

Thermal (<1 eV) electron density measurements, derived from the Mars Atmosphere and Volatile Evolution's (MAVEN) Langmuir Probe and Waves (LPW) instrument, are analyzed to produce the first statistical study of the thermal electron population in the Martian magnetotail. Coincident measurements of the local magnetic field are used to demonstrate that close to Mars, the thermal electron population is most likely to be observed at a cylindrical distance of ∼1.1 Mars radii (RM) from the central tail region during times when the magnetic field flares inward toward the central tail, compared to ∼1.3 RM during times when the magnetic field flares outward away from the central tail. Similar patterns are observed further down the magnetotail with greater variability. Thermal electron densities are highly variable throughout the magnetotail; average densities are typically ∼20–50 cm−3 within the optical shadow of Mars and can peak at ∼100 cm−3 just outside of the optical shadow. Standard deviations of 100% are observed for average densities measured throughout the tail. Analysis of the local magnetic field topology suggests that thermal electrons observed within the optical shadow of Mars are likely sourced from the nightside ionosphere, whereas electrons observed just outside of the optical shadow are likely sourced from the dayside ionosphere. Finally, thermal electrons within the optical shadow of Mars are up to 20% more likely to be observed when the strongest crustal magnetic fields point sunward than when they point tailward.
Radar Observations of Flows Leading to Substorm Onset Over Alaska
Authors: Lyons Larry R. , Liu Jiang , Nishimura Yukitoshi , Reimer Ashton S. , Bristow William A. , Hampton Don L. , Shi Xueling , Varney Roger H. , Donovan Eric F.
Published: February 2021

About 40 years after the discovery of the substorm, auroral observations were used to propose that substorm onset was triggered in the inner plasmas sheet (equatorward portion of the auroral oval) by an intrusion of the low entropy plasma by plasma sheet flow channels. Longitudinal localization makes such flow channels difficult to observe with sparse spacecraft, but they can be seen in the ionosphere via the broader, two‐dimensional coverage by ground‐based radars. We have analyzed all eight substorm auroral onset events with appropriate auroral and Poker Flat radar viewing during a radar campaign. These, together with five previously analyzed events provide evidence that intruding flow channels play an important role in substorm onsets. That the flux tube integrated entropy of this new plasma must be lower than that of the surrounding plasma implies that the change in the entropy distribution within the plasma sheet gives rises to the substorm onset instability that is seen via the growing auroral and electromagnetic waves seen with substorm auroral onset. Our analysis also adds to previous evidence that the flow channels leading to onset move into the plasma sheet/auroral oval from the open polar cap region of the magnetotail lobes/polar caps, that these flow channels move across the polar cap following their origin near the dayside boundary of the polar cap, and that substantial ground magnetic depressions associated with substorm do not occur with substorm onset but instead occur a few to several minutes later in association with expansion phase streamers.