bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physical Human–Robot Cooperation Based on Robust Motion Intention Estimation
Authors: Alevizos Konstantinos I. , Bechlioulis Charalampos P. , Kyriakopoulos Kostas J. 
Published: September 2020

SUMMARYCooperative transportation by human and robotic coworkers constitutes a challenging research field that could lead to promising technological achievements. Toward this direction, the present work demonstrates that, under a leader–follower architecture, where the human determines the object’s desired trajectory, complex cooperative object manipulation with minimal human effort may be achieved. More specifically, the robot estimates the object’s desired motion via a prescribed performance estimation law that drives the estimation error to an arbitrarily small residual set. Subsequently, the motion intention estimation is utilized in the object dynamics to determine the interaction force between the human and the object. Human effort reduction is then achieved via an impedance control scheme that employs the aforementioned estimations. The feedback relies exclusively on the robot’s force/torque, position as well as velocity measurements at its end effector, without incorporating any other information on the task. Moreover, an adaptive control scheme is adopted to relax the need for exact knowledge of the object dynamics. Finally, an extension for multiple robotic coworkers is studied and verified via simulation, while extensive experimental results for the single robot case clarify the proposed method and corroborate its efficiency.
Brazil in Antarctica: 40 years of science
Authors: Câmara Paulo E.A.S. , Barros-Platiau Ana F. , Andrade Israel De Oliveira , Hillebrand Giovanni R.L. 
Published: September 2020

AbstractIn 2021, Brazilian scientific research in Antarctica will reach its 40 anniversary, and in that period it has experienced good and bad times. How has Brazilian scientific research evolved since its first scientific mission to Antarctica? What were the conditions that enabled this research? How will Brazilian researchers work in the brand-new scientific station? Using an interdisciplinary approach, this article identifies tipping points and the national policy network that led to unstable funding policies. This article highlights four phases of Brazilian Antarctic science and states that there is a clear disconnect between the geopolitical and scientific priorities on one side and the political priorities, including the executive and the legislative powers, on the other.
Energy taxation, subsidy removal and poverty in Mexico
Authors: Labeaga José M. , Labandeira Xavier , López-Otero Xiral 
Published: September 2020

AbstractEquity and efficiency are crucial issues behind any tax reform, but they are particularly relevant in countries with high inequality and large shares of poverty. This paper provides a comprehensive socio-economic empirical assessment of Mexico's proposed (and partially implemented) tax reforms in the energy domain, and of a hypothetical partial removal of existing electricity subsidies. Using a rich household income and expenditure survey within the context of a demand system adjustment of non-durable goods, the article provides the public-revenue, environmental and distributional impacts from the simulation of different combinations of energy taxation, subsidy-removal and distributive offsets. The paper also provides detailed ex-ante evidence on the effects of compensatory devices that may contribute to the successful implementation of energy reform packages and significant poverty alleviation in Mexico.
Implications of Anomalous Crustal Provinces for Venus' Resurfacing History
Authors: Karlsson R. V. M. K. , Cheng K. W. , Crameri F. , Rolf T. , Uppalapati S. , Werner S. C. 
Published: September 2020

AbstractCurrent Venus tectonics suggests a stagnant lid mode of mantle convection. However, the planet is debated to enter an episodic regime after long quiescent periods, driven by resurfacing due to rapid subduction and global crustal recycling. Tessera regions that cover approximately 10% of Venus' surface appear to be strongly deformed, which suggests that they have survived at least the latest resurfacing event, although the composition and age of the tesserae are unknown. Based on mantle convection modeling, we studied the effects of anomalous crustal provinces (ACPs) on mantle dynamics and postoverturn lithospheric survival. As a hypothesis, we assume ACPs to be thick, compositionally anomalous, and rheologically strong units, similar to terrestrial cratons. We model Venus with a varying number of preimposed ACP units and differing lithospheric yield stress in 2‐D and 3‐D spherical geometry. The impact of ACPs on mantle dynamics and the survival of lithosphere is investigated by examining the thermal evolution, crustal thickness, and surface age distribution. We find that the number and timing of overturns are highly dependent on the yield stress and, to some degree, on the number and size of the preimposed ACPs. ACPs in particular affect the wavelength of convection and may foster the survival of lithosphere even of those portions not being part of an ACP. However, ACPs do not seem to be a good analog for tessera regions due to their exaggerated age and (likely) thickness, but—with appropriate density contrast—may be more useful representatives of Venus' highland plateaus.
Wintertime Impacts of the 2019 Super IOD on East Asia
Authors: Doi Takeshi , Behera Swadhin K. , Yamagata Toshio 
Published: September 2020

AbstractMany parts of East Asia, including Japan, experienced extremely warm conditions during the 2019–2020 winter. These were successfully predicted in October of 2019 by the 108‐member ensemble seasonal prediction system based on the SINTEX‐F climate model. By analyzing covariability of intermember anomalies defined as deviations from the ensemble mean, we have found that the active convection over the western pole of the Indian Ocean Dipole (IOD) caused these unusual conditions over East Asia by generating the meander of the subtropical jet.
Variations of Earthquake Properties Before, During, and After the 2019 M7.1 Ridgecrest, CA, Earthquake
Authors: Cheng Yifang , Ben‐Zion Yehuda 
Published: September 2020

AbstractWe attempt to clarify processes associated with the 2019 Ridgecrest earthquake sequence by analyzing space‐time variations of seismicity, potency values, and focal mechanisms of earthquakes leading to and during the sequence. Over the 20 years before the Mw7.1 mainshock, the percentage of normal faulting events decreased gradually from 25% to below 10%, indicating a long‐term increase of shear stress. The Mw6.4 and Mw7.1 ruptures terminated at areas with strong changes of seismic velocity or intersections with other faults producing arresting barriers. The aftershocks are characterized by highly diverse focal mechanisms and produced volumetric brittle deformation concentrated in a 5–10 km wide zone around the main ruptures. Early aftershocks of the Mw7.1 event extended over a wide area below typical seismogenic depth, consistent with a transient deepening of the brittle‐ductile transition. The Ridgecrest earthquake sequence produced considerable rock damage in the surrounding crust including below the nominal seismogenic zone.
Particle‐in‐Cell Simulation of Rising‐Tone Magnetosonic Waves
Authors: Sun Jicheng , Chen Lunjin , Wang Xueyi , Boardsen Scott , Lin Yu , Xia Zhiyang 
Published: September 2020

AbstractRecent observations have reported that magnetosonic waves can exhibit rising‐tone structures in the frequency‐time spectrogram. However, the generation mechanism has not been identified yet. In this paper, we investigate the generation of rising‐tone magnetosonic waves in the terrestrial magnetosphere using 1‐D particle‐in‐cell (PIC) simulations, in which the plasma consists of three components: cool electrons, cool protons and ring distribution protons. We find that the magnetosonic waves excited by the ring distribution protons can form a rising‐tone structure with frequency of the structure ranging from about 0.5Ωlh to nearly Ωlh, where Ωlh is the lower hybrid frequency. It is further demonstrated that the rising frequency of magnetosonic waves can be accounted for by the scattering of ring distribution protons. Moreover, the rising‐tone timescale obtained by PIC simulation is compared with the satellite observation. Our findings provide some new insights to understand the nonlinear evolution of plasma waves in the Earth's magnetosphere.
Analysis of Acoustic Observations of Double‐Diffusive Finestructure in the Arctic Ocean
Authors: Shibley Nicole C. , Timmermans Mary‐Louise , Stranne Christian 
Published: September 2020

AbstractDouble‐diffusive convection may occur if both temperature and salinity increase with depth, as in the Arctic Ocean. The process is identifiable by a staircase structure, with mixed layers separated by high‐gradient interfaces in temperature and salinity. These staircases, which persist if turbulence levels are weak, are widely present in the Arctic Ocean and responsible for transporting heat toward the overlying sea ice. Acoustic observations (reflection coefficients) from a broadband echo sounder are analyzed here to track the detailed evolution of interfaces in the Arctic's double‐diffusive staircase. We infer interface thicknesses from reflection coefficient profiles and find that thicknesses appear to be related to water column displacements. Further, we relate reflection coefficients to interface stratification and interpret stratification changes in the context of turbulence acting to thicken interfaces. The high‐resolution capabilities of the echo sounder allow for insights into how double‐diffusive heat fluxes and inferred mixing levels may vary in space/time.
Resonant Whistler‐Electron Interactions: MMS Observations Versus Test‐Particle Simulation
Authors: Behar E. , Sahraoui F. , Berčič L. 
Published: September 2020

AbstractWe present a novel technique to analyze VDF, which allows to capture their fine structure including wave‐particles resonances. By applying the technique to magnetospheric multiscale (MMS) data, the simultaneous observation of characteristic three‐dimensional (3‐D) signatures in the electron velocity distribution function (VDF) and intense quasi‐monochromatic waves in the terrestrial magnetosheath is investigated. The intense wave packets are characterized and modeled analytically as quasi‐parallel circularly polarized whistler waves and applied to a test‐particle simulation in view of gaining insight into the signature of the wave‐particle resonances in velocity space. Both the Landau and the cyclotron resonances were evidenced in the test‐particle simulations. The location and general shape of the test‐particle signatures do account for the observations, but the finer details, such as the symmetry of the observed signatures, are not matched, indicating either the limits of the test‐particle approach or a more fundamental physical mechanism not yet grasped. Finally, it is shown that the energization of the electrons in this precise resonance case cannot be diagnosed using the moments of the distribution function, as done with the classical E · J “dissipation” estimate.
Lower‐Band “Monochromatic” Chorus Riser Subelement/Wave Packet Observations
Authors: Tsurutani Bruce T. , Chen Rui , Gao Xinliang , Lu Quanming , Pickett Jolene S. , Lakhina Gurbax S. , Sen Abhijit , Hajra Rajkumar , Park Sang A , Falkowski Barbara J. 
Published: September 2020

AbstractThree lower‐band (f < 0.5 fce) chorus riser elements detected in the dayside generation region were studied in detail using the Van Allen Probe data. Two subelements/wave packets within each riser were examined for their wave “frequency” constancy within seven consecutive wave cycles. The seven wave cycles contained the maximum amplitudes of the subelements/packets. Maximum variance B1 zero crossings were used for the identification of wave cycle start and stop times. It is found that the frequency is constant to within ~3% (one standard deviation), with no evidence of upward frequency sweeping over the seven cycles. Continuous wavelet power spectra for the duration of the seven cycles confirm this conclusion. The implication is that a chorus riser element is composed of coherent approximately “monochromatic” steps instead of a gradual sweep in frequency over the whole element. There was no upward frequency stepping where the wave amplitude was the largest, contrary to the sideband theory prediction. It is shown that a chorus riser involves instability of cyclotron resonant energetic electrons from ~6 to ~40 keV at L = 5.8, that is, essentially the whole substorm electron energy spectrum. The above findings may have important consequences for possible wave generation mechanisms. Some new ideas for mechanisms are suggested in conclusion.
Automatic Detection and Location of Seismic Events From Time‐Delay Projection Mapping and Neural Network Classification
Authors: Mosher Stephen G. , Audet P. 
Published: September 2020

AbstractThe past several decades have seen an exponential increase in the volume of available seismic data, and with it has come the need to develop fast, automatic earthquake detection, and location algorithms. Some of the most recent and promising tools come from the field of machine learning. In this study, we combine a recent seismic detection and location method with neural network classification and analyze 4 months of continuous data recorded by a network of 76 stations in northern California. While these approaches have been used separately, our implementation is unique in that it is not constrained by source templates and avoids user‐defined detection thresholds. In particular, we partition our data set into 234,240, 3‐min long time windows with 75% overlap. For each time window, we create a 3D image that captures information about the coherence of the seismic wavefield. We then devise four features as input and train a neural network classifier to predict which time windows in the data set are likely to contain regional seismic events. These features include the second and fourth Hu image moments computed from 2D cross sections of our 3D images and statistical p values that quantify the probability of observing network‐wide power‐spectral density values at 0.2 and 0.5 s. Our neural network model predicts that 2,522 time windows contain seismic events, from which we locate 1,192 unique events.
The Effects of Degassing on Magmatic Gas Waves and Long Period Eruptive Precursors at Silicic Volcanoes
Authors: Jordan Jacob S. , Bercovici David , Liao Yang , Michaut Chloé 
Published: September 2020

AbstractCyclical ground deformation, associated seismicity, and elevated degassing are important precursors to explosive eruptions at silicic volcanoes. Regular intervals for elevated activity (6–30 hr) have been observed at volcanoes such as Mount Pinatubo in the Philippines and Soufrière Hills in Montserrat. Here, we explore a hypothesis originally proposed by Michaut et al. (2013, https://doi.org/10.1038/ngeo1928) where porosity waves containing magmatic gas are responsible for the observed periodic behavior. We use two‐phase theory to construct a model where volatile‐rich, bubbly, viscous magma rises and decompresses. We conduct numerical experiments where magma gas waves with various frequencies are imposed at the base of the model volcanic conduit. We numerically verify the results of Michaut et al. (2013, https://doi.org/10.1038/ngeo1928) and then expand on the model by allowing magma viscosity to vary as a function of dissolved water and crystal content. Numerical experiments show that gas exsolution tends to damp the growth of porosity waves during decompression. The instability and resultant growth or decay of gas wave amplitude depends strongly on the gas density gradient and the ratio of the characteristic magma extraction rate to the characteristic magma degassing rate (Damköhler number, Da). We find that slow degassing can lead to a previously unrecognized filtering effect, where low‐frequency gas waves may grow in amplitude. These waves may set the periodicity of the eruptive precursors, such as those observed at Soufrière Hills Volcano. We demonstrate that degassed, crystal‐rich magma is susceptible to the growth of gas waves which may result in the periodic behavior.
Characterization of the intergenerational impact of in utero and postnatal oxycodone exposure
Authors: Odegaard Katherine E. , Schaal Victoria L. , Clark Alexander R. , Koul Sneh , Gowen Austin , Sankarasubramani Jagadesan , Xiao Peng , Guda Chittibabu , Lisco Steven J. , Yelamanchili Sowmya V. , Pendyala Gurudutt 
Published: September 2020

AbstractPrescription opioid abuse during and after pregnancy is a rising public health concern. While earlier studies have documented that offspring exposed to opioids in utero have impaired neurodevelopment, a significant knowledge gap remains in comparing the overall development between offspring exposed in utero and postnatally. Adding a layer of complexity is the role of heredity in the overall development of these exposed offspring. To fill in these important knowledge gaps, the current study uses a preclinical rat model mimicking oxycodone (oxy) exposure in utero (IUO) and postnatally (PNO) to investigate comparative and intergenerational effects in the two different treatment groups. While significant phenotypic attributes were observed with the two treatments and across the two generations, RNA sequencing revealed alterations in the expression of key synaptic genes in the two exposed groups in both generations. RNA sequencing and post validation of genes using RT-PCR highlighted the differential expression of several neuropeptides associated with the hypocretin system, a system recently implicated in addiction. Further, behavior studies revealed anxiety-like behaviors and social deficits that persisted even in the subsequent generations in the two treatment groups. To summarize, our study for the first time reveals a new line of investigation on the potential risks associated with oxy use during and after pregnancy, specifically the disruption of neurodevelopment and intergenerational impact on behavior.
Stem/progenitor cell-based transplantation for retinal degeneration: a review of clinical trials
Authors: Wang Yiqi , Tang Zhimin , Gu Ping 
Published: September 2020

AbstractRetinal degeneration (RD) is one of the dominant causes of irreversible vision impairment and blindness worldwide. However, the current effective therapeutics for RD in the ophthalmologic clinic are unclear and controversial. In recent years, extensively investigated stem/progenitor cells—including retinal progenitor cells (RPCs), embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and mesenchymal stromal cells (MSCs)—with proliferation and multidirectional differentiation potential have presented opportunities to revolutionise the ultimate clinical management of RD. Herein, we provide a comprehensive overview on the progression of clinical trials for RD treatment using four types of stem/progenitor cell-based transplantation to replace degenerative retinal cells and/or to supplement trophic factors from the aspects of safety, effectiveness and their respective advantages and disadvantages. In addition, we also discuss the emerging role of stem cells in the secretion of multifunctional nanoscale exosomes by which stem cells could be further exploited as a potential RD therapy. This review will facilitate the understanding of scientists and clinicians of the enormous promise of stem/progenitor cell-based transplantation for RD treatment, and provide incentive for superior employment of such strategies that may be suitable for treatment of other diseases, such as stroke and ischaemia–reperfusion injury.
USP29 enhances chemotherapy-induced stemness in non-small cell lung cancer via stabilizing Snail1 in response to oxidative stress
Authors: Wu Yueguang , Zhang Yingqiu , Wang Duchuang , Zhang Yang , Zhang Jinrui , Zhang Yayun , Xu Lu , Wang Taishu , Wang Shanshan , Zhang Qingqing , Liu Fang , Zaky Mohamed Y. , Li Qiong , Sun Qianhui , Guo Dong , Liu Shuyan , Zou Lijuan , Yang Qingkai , Liu Han 
Published: September 2020

AbstractChemotherapy remains an essential part of diverse treatment regimens against human malignancies. However, recent progressions have revealed a paradoxical role of chemotherapies to induce the cancer stem cell-like features that facilitate chemoresistance and tumor dissemination, with the underlying mechanisms underinvestigated. The zinc-finger transcription factor Snail1 is a central regulator during the epithelial-mesenchymal transition process and is closely implicated in cancer progression. Snail1 expression is strictly regulated at multiple layers, with its stability governed by post-translational ubiquitylation that is counterbalanced by the activities of diverse E3 ligases and deubiquitylases. Here we identify the deubiquitylase USP29 as a novel stabilizer of Snail1, which potently restricts its ubiquitylation in a catalytic activity-dependent manner. Bioinformatic analysis reveals a reverse correlation between USP29 expression and prognosis in lung adenocarcinoma patients. USP29 is unique among Snail1 deubiquitylases through exhibiting chemotherapy-induced upregulation. Mechanistically, oxidative stresses incurred by chemotherapy stimulate transcriptional activation of USP29. USP29 upregulation enhances the cancer stem cell-like characteristics in lung adenocarcinoma cells to promote tumorigenesis in athymic nude mice. Our findings uncover a novel mechanism by which chemotherapy induces cancer stemness and suggest USP29 as a potential therapeutic target to impede the development of chemoresistance and metastasis in lung adenocarcinoma.
A lysozyme with altered substrate specificity facilitates prey cell exit by the periplasmic predator Bdellovibrio bacteriovorus
Authors: Harding Christopher J. , Huwiler Simona G. , Somers Hannah , Lambert Carey , Ray Luke J. , Till Rob , Taylor Georgina , Moynihan Patrick J. , Sockett R. Elizabeth , Lovering Andrew L. 
Published: September 2020

AbstractLysozymes are among the best-characterized enzymes, acting upon the cell wall substrate peptidoglycan. Here, examining the invasive bacterial periplasmic predator Bdellovibrio bacteriovorus, we report a diversified lysozyme, DslA, which acts, unusually, upon (GlcNAc-) deacetylated peptidoglycan. B. bacteriovorus are known to deacetylate the peptidoglycan of the prey bacterium, generating an important chemical difference between prey and self walls and implying usage of a putative deacetyl-specific “exit enzyme”. DslA performs this role, and ΔDslA strains exhibit a delay in leaving from prey. The structure of DslA reveals a modified lysozyme superfamily fold, with several adaptations. Biochemical assays confirm DslA specificity for deacetylated cell wall, and usage of two glutamate residues for catalysis. Exogenous DslA, added ex vivo, is able to prematurely liberate B. bacteriovorus from prey, part-way through the predatory lifecycle. We define a mechanism for specificity that invokes steric selection, and use the resultant motif to identify wider DslA homologues.