bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Short-Term Low-Temperature Austempering on the Microstructure and Abrasive Wear of Medium-Carbon Low-Alloy Steel
Authors: Luo Quanshun , Mei Haijuan , Kitchen Matthew , Gao Yubi , Bowen Leon
Published: April 2021

Nano-bainitic steels have attracted great attention for good wear resistance. In this research, a medium-carbon low-alloyed steel was austempered at a low temperature close to its martensite-start temperature for various times to obtain mixed microstructure of nano-bainite, martensite and retained austenite. The austempered samples were characterised comprehensively by field-emission SEM and quantitative XRD. Its two-body abrasive wear property was evaluated by sliding on a SiC abrasive disc. The results revealed the formation of initial nano-width carbide-free bainitic ferrite (BF) after austempering by 10 min, whereas the BF size and amount both increased with the austempering time. The austempered samples exhibited wear coefficients lower than the quenched martensitic sample by up to 50%. SEM and TEM observations showed wear mechanisms of micro-cutting and ploughing deformation, including the formation of a nano-laminate top layer and bending deformation in the subsurface multiphase microstructure. The decreased wear loss was attributed to the role of retained austenite in the increased plasticity.

Graphic abstract
Herleitung von Grundvorstellungen als normative Leitlinien – Beschreibung eines theoriebasierten Verfahrensrahmens
Authors: Salle Alexander , Clüver Tomma
Published: April 2021

Grundvorstellungen stellen Richtlinien für die Gestaltung von Lernprozessen sowie für eine strukturierte Erforschung mentaler Repräsentationen bereit. Wie jedoch die Herleitung von Grundvorstellungen vorgenommen werden kann, wird in der Literatur unterschiedlich beschrieben oder nur teilweise expliziert.

Im vorliegenden Beitrag wird ein Verfahrensrahmen für die Herleitung von Grundvorstellungen als normative Leitlinien vorgeschlagen. Dieser umfasst fünf Schritte: (1) Festlegung zentraler Konzepte, zu denen Grundvorstellungen formuliert werden sollen, sowie weiterer Richtlinien für den Herleitungsprozess, (2) sachanalytisch begründete Klassenbildung auf Basis relevanter mathematischer Definitionen, der Begriffsphänomenologie sowie empirischer Ergebnisse, (3) Formulierung konkreter Grundvorstellungen anhand der gebildeten Klassen und Analyse ihrer Beziehungen untereinander, (4) Bestimmung von Grundkenntnissen und Analyse der Beziehungen zu anderen Grundvorstellungen, (5) Klärung der didaktischen Relevanz.

Die Herleitung von Grundvorstellungen mit diesem Verfahrensrahmen wird anhand des Sinus- und Bruchzahlbegriffs exemplifiziert.
A numerical study of vibration-induced instrument reading capability degradation in helicopter pilots
Authors: Tamer Aykut , Zanoni Andrea , Cocco Alessandro , Masarati Pierangelo
Published: April 2021

Rotorcraft suffer from relatively high vibratory levels, due to exposure to significant vibratory load levels originating from rotors. As a result, pilots are typically exposed to vibrations, which have non-negligible consequences. Among those, one important issue is the degradation of instrument reading, which is a result of complex human-machine interaction. Both involuntary acceleration of the eyes as a result of biodynamics and vibration of the instrument panel contribute to a likely reduction in instrument reading capability, affecting flight safety. Therefore, being able to estimate the expected level of degradation in visual performance may give substantial benefits during vehicle design, allowing to make necessary adjustments while there is room for design changes or when retrofitting an existing aircraft to ensure the modifications do not adversely affect visual acuity and instrument reading ability. For this purpose, simulation is a very valuable tool as a proper model helps to understand the aircraft characteristics before conducting flight tests. This work presents the assessment of vibration-induced visual degradation of helicopter pilots under vibration exposure using a modular analysis environment. Core elements of the suggested analysis framework are an aeroelastic model of the helicopter, a model of the seat-cushion subsystem, a detailed multibody model of the human biodynamics, and a simplified model of ocular dynamics. These elements are combined into a comprehensive, fully coupled model. The contribution of each element to instrument reading degradation is examined, after defining an appropriate figure of merit that includes both eye and instrument panel vibration, in application to a numerical model representative of a medium-weight helicopter.
Solvents adjusted pure phase CoCO3 as anodes for high cycle stability
Authors: Liu Liming , Huang Xiaoxiao , Wei Zengyan , Duan Xiaoming , Zhong Bo , Xia Long , Zhang Tao , Wang Huatao , Jia Dechang , Zhou Yu , Zhang Rui
Published: April 2021

CoCO3 with high theoretical capacity has been considered as a candidate anode for the next generation of lithium-ion batteries (LIBs). However, the electrochemical performance of CoCO3 itself, especially the cyclic stability at high current density, hinders its application. Herein, pure phase CoCO3 particles with different particle and pore sizes were prepared by adjusting the solvents (diethylene glycol, ethylene glycol, and deionized water). Among them, CoCO3 synthesized with diethylene glycol (DG-CC) as the solvent shows the best electrochemical performance owing to the smaller particle size and abundant mesoporous structure to maintain robust structural stability. A high specific capacity of 690.7 mAh/g after 1000 cycles was achieved, and an excellent capacity retention was presented. The capacity was contributed by diverse electrochemical reactions and the impedance of DG-CC under different cycles was further compared. Those results provide an important reference for the structural design and stable cycle performance of pure CoCO3.
Comparison of Machine Learning Algorithms for the Quality Assessment of Wearable ECG Signals Via Lenovo H3 Devices
Authors: Fu Fan , Xiang Wentao , An Yukun , Liu Bin , Chen Xianqing , Zhu Songsheng , Li Jianqing
Published: April 2021

Purpose

Electrocardiogram (ECG) signals collected from wearable devices are easily corrupted with surrounding noise and artefacts, where the signal-to-noise ratio (SNR) of wearable ECG signals is significantly lower than that from hospital ECG machines. To meet the requirements for monitoring heart disease via wearable devices, eliminating useless or poor-quality ECG signals (e.g., lead-falls and low SNRs) can be solved by signal quality assessment algorithms.

Methods

To compensate for the deficiency of the existing ECG quality assessment system, a wearable ECG signal dataset from heart disease patients collected by Lenovo H3 devices was constructed. Then, this paper compares the performance of three machine learning algorithms, i.e., the traditional support vector machine (SVM), least-squares SVM (LS-SVM) and long short-term memory (LSTM) algorithms. Different non-morphological signal quality indices (i.e., the approximate entropy (ApEn), sample entropy (SaEn), fuzzy measure entropy (FMEn), Hurst exponent (HE), kurtosis (K) and power spectral density (PSD) features) extracted from the original ECG signals are fed into the three algorithms as input.

Results

The true positive rate, true negative rate, sensitivity and accuracy are used to evaluate the performance of each method, and the LSTM algorithm achieves the best results on these metrics (97.14%, 86.8%, 97.46% and 95.47%, respectively).

Conclusions

Among the three algorithms, the LSTM-based quality assessment method is the most suitable for the signals collected by the Lenovo H3 devices. The results also show that the combination of statistical features can effectively evaluate the quality of ECG signals.
Protective Effects of Curcumin on the Outcome of Cryopreservation in Human Sperm
Authors: Santonastaso Marianna , Mottola Filomena , Iovine Concetta , Colacurci Nicola , Rocco Lucia
Published: April 2021

Cryopreservation causes decreased sperm fertility potential due to reactive oxygen species (ROS) production and physical-chemical damage, resulting in reduced sperm viability and motility. The addition of antioxidants to freezing media could protect sperm from cryo-damage, counteracting the harmful effects of ROS. The aim of this study was to assess the effects of curcumin supplementation in freezing medium on preventing cryo-damage in human semen. Semen samples collected from fertile men were cryopreserved in freezing medium supplemented with different concentrations of curcumin (2.5, 5, 10, and 20 μM). After freezing-thawing, sperm parameters, DNA fragmentation, intracellular ROS, and glutathione peroxidase 4 (GPX4) gene expression were evaluated. Supplementation with 20 μM curcumin in freezing medium caused increases in progressive and nonprogressive motility and significant reductions in intracellular ROS and DNA fragmentation in frozen-thawed sperm cells. Following cryopreservation,GPX4 mRNA expression was significantly upregulated in thawed semen supplemented with 20 μM curcumin compared to the control. The results showed that curcumin supplementation in freezing medium was protective against human sperm parameters and sperm DNA, counteracting oxidative damage induced by the freeze-thaw process.
Skepticism in Early Modern English Literature
Authors: Sherman Anita Gilman
Published: April 2021

This ambitious account of skepticism's effects on major authors of England's Golden Age shows how key philosophical problems inspired literary innovations in poetry and prose. When figures like Spenser, Shakespeare, Donne, Herbert of Cherbury, Cavendish, Marvell and Milton question theories of language, degrees of knowledge and belief, and dwell on the uncertainties of perception, they forever change English literature, ushering it into a secular mode. While tracing a narrative arc from medieval nominalism to late seventeenth-century taste, the book explores the aesthetic pleasures and political quandaries induced by skeptical doubt. It also incorporates modern philosophical views of skepticism: those of Stanley Cavell, Ludwig Wittgenstein, Roland Barthes, and Hans Blumenberg, among others. The book thus contributes to interdisciplinary studies of philosophy and literature as well as to current debates about skepticism as a secularizing force, fostering civil liberties and religious freedoms.
Impact of empiric antibiotics for methicillin-resistant Staphylococcus aureus (MRSA) infection and associated Clostridioides difficile infection (CDI) risk: Secondary analysis of the CLEAR trial
Authors: Weiland Anastasiia S. , Lu Julia Y. , Chen Caleb S. , Tjoa Thomas , Singh Raveena , McKinnell James A. , Miller Loren G. , Huang Susan S.
Published: April 2021

We performed secondary analyses of a postdischarge decolonization trial of MRSA carriers that reduced MRSA infection and hospitalization by 30%. Hospitalized MRSA infection was associated with 7.9 days of non-MRSA antibiotics and CDI in 3.9%. Preventing MRSA infection and associated hospitalization may reduce antibiotic use and CDI incidence.
A qualitative assessment of the diagnosis and management of ventilator-associated pneumonia among critical care clinicians exploring opportunities for diagnostic stewardship
Authors: Kenaa Blaine , O’Hara Lyndsay M. , Richert Mary Elizabeth , Brown Jessica P. , Shanholtz Carl , Armahizer Michael J. , Leekha Surbhi
Published: April 2021

Background:

Prompt diagnosis and intervention for ventilator-associated pneumonia (VAP) is critical but can lead to overdiagnosis and overtreatment.

Objectives:

We investigated healthcare provider (HCP) perceptions and challenges associated with VAP diagnosis, and we sought to identify opportunities for diagnostic stewardship.

Methods:

We conducted a qualitative study of 30 HCPs at a tertiary-care hospital. Participants included attending physicians, residents and fellows (trainees), advanced practice providers (APPs), and pharmacists. Interviews were composed of open-ended questions in 4 sections: (1) clinical suspicion and thresholds for respiratory culture ordering, (2) preferences for respiratory sample collection, (3) culture report interpretation, and (4) VAP diagnosis and treatment. Interviews transcripts were analyzed using Nvivo 12 software, and responses were organized into themes.

Results:

Overall, 10 attending physicians (75%) and 16 trainees (75%) trainees and APPs believed they were overdiagnosing VAP; this response was frequent among HCPs in practice 5–10 years (91%, n = 12). Increased identification of bacteria as a result of frequent respiratory culturing, misinterpretation of culture data, and fear of missing diagnosis were recognized as drivers of overdiagnosis and overtreatment. Although most HCPs rely on clinical and radiographic changes to initiate work-up, the fear of missing a diagnosis leads to sending cultures even in the absence of those changes.

Conclusions:

HCPs believe that VAP overdiagnosis and overtreatment are common due to fear of missing diagnosis, overculturing, and difficulty distinguishing colonization from infection. Although we identified opportunities for diagnostic stewardship, interventions influencing the ordering of cultures and starting antimicrobials will need to account for strongly held beliefs and ICU practices.
Interfacility transfer communication of multidrug-resistant organism colonization or infection status: Practices and barriers in the acute-care setting
Authors: Ellingson Katherine D. , Noble Brie N. , Buser Genevieve L. , Snyder Graham M. , McGregor Jessina C. , Rock Clare , Chopra Teena , Mody Lona , Furuno Jon P. ,   SHEA Research Committee
Published: April 2021

Objective:

To describe interfacility transfer communication (IFTC) methods for notification of multidrug-resistant organism (MDRO) status in a diverse sample of acute-care hospitals.

Design:

Cross-sectional survey.

Participants:

Hospitals within the Society for Healthcare Epidemiology of America (SHEA) Research Network (SRN).

Methods:

SRN members completed an electronic survey on protocols and methods for IFTC. We assessed differences in IFTC frequency, barriers, and perceived benefit by presence of an IFTC protocol.

Results:

Among 136 hospital representatives who were sent the survey, 54 (40%) responded, of whom 72% reported having an IFTC protocol in place. The presence of a protocol did not differ significantly by hospital size, academic affiliation, or international status. Of those with IFTC protocols, 44% reported consistent notification of MDRO status (>75% of the time) to receiving facilities, as opposed to 13% from those with no IFTC protocol (P = .04). Respondents from hospitals with IFTC protocols reported significantly fewer barriers to communication compared to those without (2.8 vs 4.3; P = .03). Overall, however, most respondents (56%) reported a lack of standardization in communication. Presence of an IFTC protocol did not affect whether respondents perceived IFTC protocols as having a significant impact on infection prevention or antimicrobial stewardship.

Conclusions:

Most respondents reported having an IFTC protocol, which was associated with reduced communication barriers at transfer. Standardization of protocols and clarity about expectations for sending and receipt of information related to MDRO status may facilitate IFTC and promote appropriate and timely infection prevention practices.
Mineral and natural films change the physical–chemical properties of grapes and modulate oviposition behaviour of Ceratitis capitata Wiedemann (Diptera: Tephritidae)
Authors: da Costa D. R. , Leite S. A. , Moreira A. A. , Perez-Maluf R. , Novaes Q. S. , dos Santos M.P. , dos Santos M. M. , Joachim-Bravo I. S. , Castellani M. A.
Published: April 2021

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), is one of the main pests of fruit, worldwide, and the use of population suppression method with low environmental impact is an increasingly strong requirement of the consumer market. The aim of this study was to evaluate the effect of mineral and natural films on the physical–chemical properties of grapes (Vitis vinifera L.), cultivar Itália, and oviposition behaviour of C. capitata. Fruits were immersed in suspensions (100 and 200 g L−1) of mineral (kaolin Surround®WP, kaolin 607, kaolin 608, kaolin 611 and talc) and natural films (chitosan, cassava starch, potato starch and guar gum 5.0 g L−1) and distilled water (control). After drying, fruits were exposed to C. capitata pairs of males and females for 24 h in choice and non-choice tests; the number of punctures with and without eggs, eggs per fruit and behavioural response of fly to treated and untreated fruits were recorded. Results obtained in this study are promising, given the scientific evidence that films of mineral particles such as kaolin (Surround®, 607, 608 and 611) changed the firmness, luminosity, chroma and hue angle of grapes and reduced the oviposition of C. capitata. In addition, our results also showed that natural polymers do not deter C. capitata females, but rather seem to stimulate oviposition.
Finance in the New U.S. Economy: Local Finance and Service Job Growth in the Post-industrial Economy
Authors: Berger Elizabeth A.
Published: April 2021

I examine whether local bank finance facilitated the transition to a service-based economy in the U.S. I identify a causal role for local finance in service job creation. I use county-level changes to alcohol laws as demand shocks to service employers across a subsample of U.S. counties. Counties with more local finance experience more service job creation. This leads to labor market transitions that reflect shifts in the broader economy. Information asymmetry and collateral constraints connect local finance to service sector employment. The findings identify a unique role for local finance in the evolution to a postindustrial service-based economy.
What can be learned from litigation in otology? A review of clinical negligence claims in England 2013–2018
Authors: McClenaghan F , Ho C , Machin J T , Briggs T W R , Marshall A , Navaratnam A V
Published: April 2021

Background

Litigation in the National Health Service continues to rise with a 9.4 per cent increase in clinical negligence claims from the period 2018 and 2019 to the period 2019 and 2020. The cost of these claims now accounts for 1.8 per cent of the National Health Service 2019 to 2020 budget. This study aimed to identify the characteristics of clinical negligence claims in the subspecialty of otology.

Methods

This study was a retrospective review of all clinical negligence claims in otology in England held by National Health Service Resolution between April 2013 and April 2018.

Results

There were 171 claims in otology, 24 per cent of all otolaryngology claims, with a potential cost of £24.5 million. Over half of these were associated with hearing loss. Stapedectomy was the highest mean cost per claim operation at £769 438. The most common reasons for litigation were failure or delay in treatment (23 per cent), failure or delay in diagnosis (20 per cent), intra-operative complications (15 per cent) and inadequate consent (13 per cent).

Conclusion

There is a risk of high-cost claims in otology, especially with objective injuries such as hearing loss and facial nerve injury.
Fully distributed actor-critic architecture for multitask deep reinforcement learning
Authors: Valcarcel Macua Sergio , Davies Ian , Tukiainen Aleksi , de Cote Enrique Munoz
Published: April 2021

We propose a fully distributed actor-critic architecture, named diffusion-distributed-actor-criticDiff-DAC, with application to multitask reinforcement learning (MRL). During the learning process, agents communicate their value and policy parameters to their neighbours, diffusing the information across a network of agents with no need for a central station. Each agent can only access data from its local task, but aims to learn a common policy that performs well for the whole set of tasks. The architecture is scalable, since the computational and communication cost per agent depends on the number of neighbours rather than the overall number of agents. We derive Diff-DAC from duality theory and provide novel insights into the actor-critic framework, showing that it is actually an instance of the dual-ascent method. We prove almost sure convergence of Diff-DAC to a common policy under general assumptions that hold even for deep neural network approximations. For more restrictive assumptions, we also prove that this common policy is a stationary point of an approximation of the original problem. Numerical results on multitask extensions of common continuous control benchmarks demonstrate that Diff-DAC stabilises learning and has a regularising effect that induces higher performance and better generalisation properties than previous architectures.
Tahiti Petrel Pseudobulweria rostrata population decline at a nickel-mining site: a critical need for adapted conservation strategies
Authors: PAGENAUD ANGÉLIQUE , BOURGEOIS KAREN , DROMZÉE SYLVAIN , THIBAULT MARTIN , CHAGNEAU GUILLAUME , BARRÉ NICOLAS , BOUYÉ ÉLODIE , CHARTENDRAULT VINCENT , DELELIS NICOLAS , DIJOUX JULIEN , PATROIS MAGALIE , SPAGGIARI JÉRÔME , VIDAL ÉRIC
Published: April 2021

New Caledonia hosts a large part of the world’s breeding population of the Tahiti Petrel Pseudobulweria rostrata. This rare, cryptic and little-studied seabird nests locally in the mountains up to 1,200 m in altitude, particularly in ultramafic (i.e. nickel-rich) areas where mining activity is a major threat. The considerable development of mining activities in New Caledonia over the past decade raises concerns about its potential impacts on breeding populations through both direct habitat destruction and side effects such as pollution or repeated disturbances. This context calls for a dedicated assessment of the persistence of local populations to guide the design of an adapted conservation strategy and potential restoration programmes. We investigated the impact of mining activities on a Tahiti Petrel population when surveyed pre-mining (2004–2007) and following a period of full mining (2017–2018). The vocal activity was assessed at a total of 114 night-call count stations spread over the Koniambo massif. Areas with ground-originated vocal activity were then searched during daytime for nesting evidence. Finally, georeferenced aerial photos were used to estimate habitat degradation as the percentage of bare soil cover (PBSC) within a 400-m radius around each call count station. Our study revealed a dramatic decline in the Tahiti Petrel vocal activity and a desertion of breeding habitats during the full-mining period compared to the pre-mining period. In light of these results, we recommend designing safe breeding areas and combining restoration methods including social attraction, predation control and artificial burrows at mining sites.
Balloon dilatation versus surgical valvotomy for congenital aortic stenosis: a propensity score matched study
Authors: Auld Benjamin C. , Donald Julia S. , Lwin Naychi , Betts Kim , Alphonso Nelson O. , Venugopal Prem S. , Justo Robert N. , Ward Cameron J. , Konstantinov Igor E. , Karl Tom R. , Anderson Benjamin W.
Published: April 2021

Background:

Balloon valvuloplasty and surgical aortic valvotomy have been the treatment mainstays for congenital aortic stenosis in children. Choice of intervention often differs depending upon centre bias with limited relevant, comparative literature.

Objectives:

This study aims to provide an unbiased, contemporary matched comparison of these balloon and surgical approaches.

Methods:

Retrospective analysis of patients with congenital aortic valve stenosis who underwent balloon valvuloplasty (Queensland Children’s Hospital, Brisbane) or surgical valvotomy (Royal Children’s Hospital, Melbourne) between 2005 and 2016. Patients were excluded if pre-intervention assessment indicated ineligibility to either group. Propensity score matching was performed based on age, weight, and valve morphology.

Results:

Sixty-five balloon patients and seventy-seven surgical patients were included. Overall, the groups were well matched with 18 neonates/25 infants in the balloon group and 17 neonates/28 infants in the surgical group. Median age at balloon was 92 days (range 2 days – 18.8 years) compared to 167 days (range 0 days – 18.1 years) for surgery (rank-sum p = 0.08). Mean follow-up was 5.3 years. There was one late balloon death and two early surgical deaths due to left ventricular failure. There was no significant difference in freedom from reintervention at latest follow-up (69% in the balloon group and 70% in the surgical group, p = 1.0).

Conclusions:

Contemporary analysis of balloon aortic valvuloplasty and surgical aortic valvotomy shows no difference in overall reintervention rates in the medium term. Balloon valvuloplasty performs well across all age groups, achieving delay or avoidance of surgical intervention.
IS IT REALLY ABOUT BEING BRITISH?
Authors: Dabbagh Hossein
Published: April 2021

In this short piece, I argue in favour of the practice of imagining ‘others’ in a global way and taking universal moral thinking seriously. We are in need of a sense of global identity which can then create global moral thinking. In this way, we can start to see and treat global challenges, such as the environment, social justice, poverty, racism and Covid-19, more effectively.
An Energetic View on the Geographical Dependence of the Fast Aerosol Radiative Effects on Precipitation
Authors: Dagan Guy , Stier Philip , Watson‐Parris Duncan
Published: April 2021

By interacting with radiation, aerosols perturb the Earth’s energy budget and thus the global precipitation amount. It was previously shown that aerosol‐radiation interactions lead to a reduction in the global‐mean precipitation amount. We have further demonstrated in aqua‐planet simulations that the local response to absorbing aerosols differs between the tropics and the extra‐tropics. In this study we incorporate an energy budget perspective to further examine the latitudinal‐dependence of the effect of aerosol‐radiation interaction on precipitation in idealized global simulations. We demonstrate that the transition between a positive local precipitation response in the tropics and a negative local precipitation response in the extra‐tropics occurs at relatively low latitudes (∼10°), indicating a transition between the deep‐tropics (in which the Coriolis force is low, hence direct thermally driven circulation, and associated divergence/convergence of energy/moisture, can form as a result of the diabatic‐heating) and their surroundings. In addition, we gradually increase the level of complexity of the simulations and demonstrate that, in the case of absorbing aerosols, the effect of land is to counteract some of the response both inside and outside the deep‐tropics due to the reduction in surface latent‐heat flux that opposes the diabatic‐heating. The effect of scattering aerosols is also examined and demonstrates a decrease in precipitation over land in both the tropics and extra‐tropics and no effect over the ocean. Finally, we examine these results in a more realistic set‐up and demonstrate that, although the physical mechanisms still operate, they are not significant enough to be discerned from the model’s natural‐variability.
Space‐Borne Estimation of Volcanic Sulfate Aerosol Lifetime
Authors: Li Chi , Cohen Ronald C.
Published: April 2021

Aerosols are an important component of the climate system affecting visibility, clouds, and climate. They are also transported over short and long distances with consequences for continental‐scale nutrient availability. Processes that remove aerosols from the atmosphere are difficult to evaluate with observations in isolation from aerosol sources. As a result, a quantitative assessment of uncertainties in our understanding of aerosols is limited and narrowing of those uncertainties is difficult to demonstrate. In this study, we use satellite observations of sulfur dioxide (SO2) and aerosols downwind of the Kīlauea volcano during May–September 2008. We derive the SO2 emission rate, the loss rate of SO2 that is indicative of the production rate of sulfate aerosols, and the subsequent removal rate of the formed sulfate. The result is the first determination of volcanic sulfate aerosol lifetime, 40–64 h, directly from satellite observations. The derived sulfate lifetime is significantly lower than the global average (3–5.5 days) and reflects the rapid wet scavenging of this plume.
Joint Inversion for Surface Accumulation Rate and Geothermal Heat Flow From Ice‐Penetrating Radar Observations at Dome A, East Antarctica. Part II: Ice Sheet State and Geophysical Analysis
Authors: Wolovick M. J. , Moore J. C. , Zhao L.
Published: April 2021

Dome A is the summit of the East Antarctic Ice Sheet, underlain by the rugged Gamburtsev Subglacial Mountains. The rugged basal topography produces a complex hydrological system featuring basal melt, water transport and storage, and freeze‐on. In a companion study, we used an inverse model to infer the spatial distributions of geothermal heat flow (GHF) and accumulation rate that best fit a variety of observational constraints. Here, we present and analyze the best‐fit state of the ice sheet in detail. Our modeled result agrees well with the observed water bodies and freeze‐on structures, while also predicting a significant amount of unobserved water and suggesting a change in stratigraphic interpretation that reduces the volume of the freeze‐on units. Our modeled stratigraphy agrees well with observations, and we predict that there will be two distinct patches of ice up to 1.5 Ma suitable for ice coring underneath the divide. Past divide migration could have interrupted stratigraphic continuity at the old ice patches, but various indirect lines of evidence suggest that the divide has been stable for about the last one and a half glacial cycles, which is an encouraging but not definitive sign for stability in the longer term. Finally, our GHF estimate is higher than previous estimates for this region, but consistent with possible heterogeneity in crustal heat production.
Selecting Indicators and Optimizing Decision Rules for Long‐Term Water Resources Planning
Authors: Murgatroyd A. , Hall J. W.
Published: April 2021

Decision rules provide an intuitive framework for water resources planning. Having adopted a rule‐based plan, decision makers can monitor critical variables to trigger timely adaptation actions when the variables pass their predetermined thresholds. However, establishing a strategy that is comprised of a set of decision rules raises methodological challenges: (i) to identify observable indicators that provide reliable information about current and future change, (ii) to choose suitable statistics to characterize nonstationary time series that are germane to system performance, and (iii) to optimize threshold levels that trigger interventions. We propose a methodology that addresses these methodological challenges whilst explicitly balancing expected risks of water shortages with the costs of intervention in the water supply system. The four‐step framework uses a multiobjective evolutionary algorithm to search for and to identify the combinations of indicator‐informed decision rules that govern if, when, and what supply options should be included in the water resource system. The rule‐based strategies are dynamically tested against an extensive ensemble of future climate and demand scenarios to examine the trade‐offs between strategy cost and level of service. The framework is applied to the London water system (England) using regional climate simulations to identify strategic rules for a 60‐year planning period. The results demonstrate the utility of the framework, identifying observable indicators and decision thresholds that are used in optimal rule‐based planning strategies. In key areas of the solution space, rule‐based strategies reduce expected restriction costs on average by 13.1%, and as much as 24.1%, for a given intervention cost.
PiAutoStage: An Open‐Source 3D Printed Tool for the Automatic Collection of High‐Resolution Microscope Imagery
Authors: Steiner R. Alex , Rooney Tyrone O.
Published: April 2021

We have created an open‐source 3D printable microscope automatic stage and integrated camera system capable of providing a means for imaging microscope slides—the PiAutoStage. The PiAutoStage was developed to interface with the high‐quality optics of existing microscopes by creating an adaptable system that can be used in conjunction with a range of microscope configurations. The PiAutoStage automatically captures the entire area of a microscope slide in a series of overlapping high‐resolution images, which can then be stitched into a single panoramic image. We have demonstrated the utility of the PiAutoStage when attached to a transmitted light microscope by creating high‐fidelity image stacks of rock specimens in plane polarized and cross‐polarized light. We have shown that the PiAutoStage is compatible with microscopes that do not currently have a camera attachment by using two different optical trains within the same microscope: one set of imagery collected through the photography tube of a trinocular microscope, and a second set through a camera mounted to an ocular. We furthermore establish the broad adaptability of the PiAutoStage system by attaching it to a reflected light stereo dissection microscope to capture images of microfossils. We discuss strategies for the online delivery of these large‐sized images in a data efficient manner through the application of tiled imagery and open‐source Java‐based web viewers. The low cost of the PiAutoStage system, combined with the data‐efficient mechanisms of online delivery make this system an important tool in promoting the universal accessibility of high‐resolution microscope imagery.
Statistical Study of Foreshock Transients in the Midtail Foreshock
Authors: Liu Terry Z. , Zhang Hui , Wang Chih‐Ping , Angelopoulos Vassilis , Vu Andrew , Wang Xueyi , Lin Yu
Published: April 2021

In the dayside foreshock, many foreshock transients have been observed and simulated. Because of their strong dynamic pressure perturbations, foreshock transients can disturb the local bow shock, magnetosheath, magnetopause, and thus the magnetosphere‐ionosphere system. They can also accelerate particles contributing to shock acceleration. Recent observations and simulations showed that foreshock transients also exist in the midtail foreshock, which can continuously disturb the nightside bow shock, magnetosheath, and magnetopause while propagating tailward for tens of minutes. To further understand the characteristics of midtail foreshock transients, we studied them statistically using Acceleration Reconnection Turbulence & Electrodynamics of Moon’s Interaction with the Sun observations. We selected 111 events that have dynamic pressure decrease along the local bow shock normal by more than 50%. We show that the dynamic pressure decrease is contributed by both density decrease and speed decrease. Around 90% of the events have electron temperature increase by more than 10% with a temperature change ratio proportional to the solar wind speed. Midtail foreshock transients more likely occur at the dawnside than the duskside. They are more significant closer to the bow shock and rather stable along the tailward direction. They have similar formation conditions compared to the dayside foreshock transients, except the ones related to the bow shock geometry. Our study indicates that the characteristics of foreshock transients based on dayside observations need to be generalized. Our study also implies that foreshock transients can exist for tens of minutes (even longer for larger planar shocks), continuously disturbing the local shock and accelerating/heating particles.
On the origin and evolution of SARS-CoV-2
Authors: Singh Devika , Yi Soojin V.
Published: April 2021

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the ongoing global outbreak of a coronavirus disease (herein referred to as COVID-19). Other viruses in the same phylogenetic group have been responsible for previous regional outbreaks, including SARS and MERS. SARS-CoV-2 has a zoonotic origin, similar to the causative viruses of these previous outbreaks. The repetitive introduction of animal viruses into human populations resulting in disease outbreaks suggests that similar future epidemics are inevitable. Therefore, understanding the molecular origin and ongoing evolution of SARS-CoV-2 will provide critical insights for preparing for and preventing future outbreaks. A key feature of SARS-CoV-2 is its propensity for genetic recombination across host species boundaries. Consequently, the genome of SARS-CoV-2 harbors signatures of multiple recombination events, likely encompassing multiple species and broad geographic regions. Other regions of the SARS-CoV-2 genome show the impact of purifying selection. The spike (S) protein of SARS-CoV-2, which enables the virus to enter host cells, exhibits signatures of both purifying selection and ancestral recombination events, leading to an effective S protein capable of infecting human and many other mammalian cells. The global spread and explosive growth of the SARS-CoV-2 population (within human hosts) has contributed additional mutational variability into this genome, increasing opportunities for future recombination.
Brain cells derived from Alzheimer’s disease patients have multiple specific innate abnormalities in energy metabolism
Authors: Ryu Woo-In , Bormann Mariana K. , Shen Minqi , Kim Dohoon , Forester Brent , Park Yeongwon , So Jisun , Seo Hyemyung , Sonntag Kai-C. , Cohen Bruce M.
Published: April 2021

Altered energy metabolism has been implicated both in aging and the pathogenesis of late-onset Alzheimer’s disease (LOAD). However, it is unclear which anomalies are acquired phenotypes and which are inherent and predispose to disease. We report that neural progenitor cells and astrocytes differentiated from LOAD patient-derived induced pluripotent stem cells exhibit multiple inter-related bioenergetic alterations including: changes in energy production by mitochondrial respiration versus glycolysis, as a consequence of alterations in bioenergetic substrate processing and transfer of reducing agents, reduced levels of NAD/NADH, diminished glucose uptake and response rates to insulin (INS)/IGF-1 signaling, decreased INS receptor and glucose transporter 1 densities, and changes in the metabolic transcriptome. Our data confirm that LOAD is a “multi-hit” disorder and provide evidence for innate inefficient cellular energy management in LOAD that likely predisposes to neurodegenerative disease with age. These processes may guide the development and testing of diagnostic procedures or therapeutic agents.
Incerto-thalamic modulation of fear via GABA and dopamine
Authors: Venkataraman Archana , Hunter Sarah C. , Dhinojwala Maria , Ghebrezadik Diana , Guo JiDong , Inoue Kiyoshi , Young Larry J. , Dias Brian George
Published: April 2021

Fear generalization and deficits in extinction learning are debilitating dimensions of Post-Traumatic Stress Disorder (PTSD). Most understanding of the neurobiology underlying these dimensions comes from studies of cortical and limbic brain regions. While thalamic and subthalamic regions have been implicated in modulating fear, the potential for incerto-thalamic pathways to suppress fear generalization and rescue deficits in extinction recall remains unexplored. We first used patch-clamp electrophysiology to examine functional connections between the subthalamic zona incerta and thalamic reuniens (RE). Optogenetic stimulation of GABAergic ZI → RE cell terminals in vitro induced inhibitory post-synaptic currents (IPSCs) in the RE. We then combined high-intensity discriminative auditory fear conditioning with cell-type-specific and projection-specific optogenetics in mice to assess functional roles of GABAergic ZI → RE cell projections in modulating fear generalization and extinction recall. In addition, we used a similar approach to test the possibility of fear generalization and extinction recall being modulated by a smaller subset of GABAergic ZI → RE cells, the A13 dopaminergic cell population. Optogenetic stimulation of GABAergic ZI → RE cell terminals attenuated fear generalization and enhanced extinction recall. In contrast, optogenetic stimulation of dopaminergic ZI → RE cell terminals had no effect on fear generalization but enhanced extinction recall in a dopamine receptor D1-dependent manner. Our findings shed new light on the neuroanatomy and neurochemistry of ZI-located cells that contribute to adaptive fear by increasing the precision and extinction of learned associations. In so doing, these data reveal novel neuroanatomical substrates that could be therapeutically targeted for treatment of PTSD.
Precision radiogenomics: fusion biopsies to target tumour habitats in vivo
Authors: Crispin-Ortuzar Mireia , Sala Evis
Published: April 2021

High-grade serous ovarian cancer lesions display a high degree of heterogeneity on CT scans. We have recently shown that regions with distinct imaging profiles can be accurately biopsied in vivo using a technique based on the fusion of CT and ultrasound scans.
Matrix stiffness changes affect astrocyte phenotype in an in vitro injury model
Authors: Hu Yan , Huang Guoyou , Tian Jin , Qiu Jinbin , Jia Yuanbo , Feng Dayun , Wei Zhao , Li Sidi , Xu Feng
Published: April 2021

Injury to the central nervous system (CNS) usually leads to the activation of astrocytes, followed by glial scar formation. The formation of glial scars from active astrocytes in vivo has been found to be dependent on the cell microenvironment. However, how astrocytes respond to different microenvironmental cues during scar formation, such as changes in matrix stiffness, remains elusive. In this work, we established an in vitro model to assess the responses of astrocytes to matrix stiffness changes that may be related to pathophysiology. The investigated hydrogel backbones are composed of collagen type I and alginate. The stiffness of these hybrid hydrogels can be dynamically changed by association or dissociation of alginate chains through adding crosslinkers of calcium chloride or a decrosslinker of sodium citrate, respectively. We found that astrocytes obtain different phenotypes when cultured in hydrogels of different stiffnesses. The obtained phenotypes can be switched in situ when changing matrix stiffness in the presence of cells. Specifically, matrix stiffening reverts astrogliosis, whereas matrix softening initiates astrocytic activation in 3D. Moreover, the effect of matrix stiffness on astrocytic activation is mediated by Yes-associated protein (YAP), where YAP inhibition enhances the upregulation of GFAP and contributes to astrogliosis. To investigate the underlying mechanism of matrix stiffness-dependent GFAP expression, we also developed a mathematical model to describe the time-dependent dynamics of biomolecules involved in the matrix stiffness mechanotransduction process of astrocytes. The modeling results further indicate that the effect of matrix stiffness on cell fate and behavior may be related to changes in the cytoskeleton and subsequent activity of YAP. The results from this study will guide researchers to re-examine the role of matrix stiffness in reactive astrogliosis in vivo and inspire the development of a novel therapeutic approach for controlling glial scar formation following injury, enabling axonal regrowth and improving functional recovery by exploiting the benefits of mechanobiology studies.
Hollow medium-entropy alloy nanolattices with ultrahigh energy absorption and resilience
Authors: Surjadi James Utama , Feng Xiaobin , Fan Rong , Lin Weitong , Li Xiaocui , Lu Yang
Published: April 2021

Hollow micro/nanolattices have emerged in recent years as a premium solution compared to conventional foams or aerogels for mechanically robust lightweight structures. However, existing hollow metallic micro/nanolattices often cannot exhibit high toughness due to the intrinsic brittleness from localized strut fractures, limiting their broad applications. Here, we report the development of hollow CoCrNi medium-entropy alloy (MEA) nanolattices, which exhibit high specific energy absorption (up to 25 J g−1) and resilience (over 90% recoverability) by leveraging size-induced ductility and rationally engineered MEA microstructural defects. This strategy provides a pathway for the development of ultralight, damage-resistant metallic metamaterials for a myriad of structural and functional applications.
High-yield, wafer-scale fabrication of ultralow-loss, dispersion-engineered silicon nitride photonic circuits
Authors: Liu Junqiu , Huang Guanhao , Wang Rui Ning , He Jijun , Raja Arslan S. , Liu Tianyi , Engelsen Nils J. , Kippenberg Tobias J.
Published: April 2021

Low-loss photonic integrated circuits and microresonators have enabled a wide range of applications, such as narrow-linewidth lasers and chip-scale frequency combs. To translate these into a widespread technology, attaining ultralow optical losses with established foundry manufacturing is critical. Recent advances in integrated Si3N4 photonics have shown that ultralow-loss, dispersion-engineered microresonators with quality factors Q > 10 × 106 can be attained at die-level throughput. Yet, current fabrication techniques do not have sufficiently high yield and performance for existing and emerging applications, such as integrated travelling-wave parametric amplifiers that require meter-long photonic circuits. Here we demonstrate a fabrication technology that meets all requirements on wafer-level yield, performance and length scale. Photonic microresonators with a mean Q factor exceeding 30 × 106, corresponding to 1.0 dB m−1 optical loss, are obtained over full 4-inch wafers, as determined from a statistical analysis of tens of thousands of optical resonances, and confirmed via cavity ringdown with 19 ns photon storage time. The process operates over large areas with high yield, enabling 1-meter-long spiral waveguides with 2.4 dB m−1 loss in dies of only 5 × 5 mm2 size. Using a response measurement self-calibrated via the Kerr nonlinearity, we reveal that the intrinsic absorption-limited Q factor of our Si3N4 microresonators can exceed 2 × 108. This absorption loss is sufficiently low such that the Kerr nonlinearity dominates the microresonator’s response even in the audio frequency band. Transferring this Si3N4 technology to commercial foundries can significantly improve the performance and capabilities of integrated photonics.