bluuebunny/crossref_metadata_2025 huggingface dataset:
Detecting clusters in multivariate response regression
Authors: Price Bradley S. , Allenbrand Corban , Sherwood Ben
Published: February 2021

Multivariate regression, which can also be posed as a multitask machine learning problem, is used to better understand multiple outputs based on a given set of inputs. Many methods have been proposed on how to utilize shared information about responses with applications in fields such as economics, genomics, advanced manufacturing, and precision medicine. Interest in these areas coupled with the rise of large data sets (“big data”) has generated interest in how to make the computations more efficient, but also to develop methods that account for the heterogeneity that may exist between responses. One way to exploit this heterogeneity between responses is to use methods that detect groups, also called clusters, of related responses. These methods provide a framework that can increase computational speed and account for complexity of relationships of a large number of responses. With this flexibility, comes additional challenges such as how to identify these clusters of responses, model selection, and the development of more complex algorithms that combine concepts from both the supervised and unsupervised learning literature. We explore current state of the art methods, present a framework to better understand methods that utilize or detect clusters of responses, and provide insights on the computational challenges associated with this framework. Specifically we present a simulation study that discusses the challenges with model selection when detecting clusters of responses of interest. We also comment on extensions and open problems that are of interest to both the research and practitioner communities.

This article is categorized under:

Statistical Learning and Exploratory Methods of the Data Sciences > Clustering and Classification

Statistical Learning and Exploratory Methods of the Data Sciences > Exploratory Data Analysis

Statistical Learning and Exploratory Methods of the Data Sciences > Modeling Methods
Cancer‐associated‐platelet‐inspired nanomedicines for cancer therapy
Authors: Geranpayehvaghei Marzieh , Dabirmanesh Bahareh , Khaledi Mohammad , Atabakhshi‐Kashi Mona , Gao Chao , Taleb Mohammad , Zhang Yinlong , Khajeh Khosro , Nie Guangjun
Published: February 2021

Platelets, with hemostasis and thrombosis activities, are one of the key components in the blood circulation. As a guard, they rapidly respond to any abnormal blood vessel injury signal and release their granules' contents, which induce their adhesion and aggregation on wound site for hemostasis. Recently, increasing evidence has indicated that platelets are critically involved in the growth and metastasis of cancer cells by releasing a variety of cytokines and chemokines to stimulate cancer cell proliferation and various angiogenic regulators to accelerate tumor angiogenesis. Platelets also secrete active transforming growth factor beta (TGF‐β) to promote the epithelial–mesenchymal transition of cancer cells and their extravasation from primary site, and form microthrombus on the surface of cancer cells to protect them from immune attack and high‐speed shear force in the circulation. Therefore, blocking platelet–cancer cell interaction may be an attractive strategy to treat primary tumor and/or prevent cancer metastasis. However, systemic inhibition or depletion of platelets brings risk of severe bleeding complication. Cancer‐associated‐platelets‐targeted nanomedicines and biomimetic nanomedicines coated with platelet membrane can be used for targeted anticancer drug delivery, due to their natural targeting ability to tumor cells and platelets. In the current review, we first summarized the platelet mechanisms of action in physiological condition and their multiple roles in cancer progression and conventional antiplatelet therapeutics. We then highlighted the recent progress on the design and fabrication of cancer‐associated‐platelet‐targeted nanomedicines and platelet membrane coating nanomedicines for cancer therapy. Finally, we discussed opportunities and challenges and offered our thoughts for the future development.

This article is categorized under:

Therapeutic Approaches and Drug Discovery > Emerging Technologies

Biology‐Inspired Nanomaterials > Lipid‐Based Structures
Biohybrid robotics: From the nanoscale to the macroscale
Authors: Mestre Rafael , Patiño Tania , Sánchez Samuel
Published: February 2021

Biohybrid robotics is a field in which biological entities are combined with artificial materials in order to obtain improved performance or features that are difficult to mimic with hand‐made materials. Three main level of integration can be envisioned depending on the complexity of the biological entity, ranging from the nanoscale to the macroscale. At the nanoscale, enzymes that catalyze biocompatible reactions can be used as power sources for self‐propelled nanoparticles of different geometries and compositions, obtaining rather interesting active matter systems that acquire importance in the biomedical field as drug delivery systems. At the microscale, single enzymes are substituted by complete cells, such as bacteria or spermatozoa, whose self‐propelling capabilities can be used to transport cargo and can also be used as drug delivery systems, for in vitro fertilization practices or for biofilm removal. Finally, at the macroscale, the combinations of millions of cells forming tissues can be used to power biorobotic devices or bioactuators by using muscle cells. Both cardiac and skeletal muscle tissue have been part of remarkable examples of untethered biorobots that can crawl or swim due to the contractions of the tissue and current developments aim at the integration of several types of tissue to obtain more realistic biomimetic devices, which could lead to the next generation of hybrid robotics. Tethered bioactuators, however, result in excellent candidates for tissue models for drug screening purposes or the study of muscle myopathies due to their three‐dimensional architecture.

This article is categorized under:

Therapeutic Approaches and Drug Discovery > Emerging Technologies

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology
Collective dynein transport of the nucleus by pulling on astral microtubules during Saccharomyces cerevisiae mitosis
Authors: Jain Kunalika , Khetan Neha , Yadav Shivani A. , Palani Saravanan , Athale Chaitanya A.
Published: February 2021

Positioning the nucleus at the bud neck during Saccharomyces cerevisiae mitosis involves pulling forces of cytoplasmic dynein localized in the daughter cell. Although genetic analysis has revealed a complex network positioning the nucleus, quantification of the forces acting on the nucleus and the number of dyneins driving the process has remained difficult. To better understand the collective forces involved in nuclear positioning, we compare a model of dyneins‐driven microtubule (MT) pulling, MT pushing, and cytoplasmic drag to experiments. During S. cerevisiae mitosis, MTs interacting with the cortex nucleated by the daughter spindle pole body (SPB) (SPB‐D) are longer than the mother SPB (SPB‐M), increasing further during spindle elongation in anaphase. Interphasic SPB mobility is effectively diffusive, while the mitotic mobility is directed. By optimizing a computational model of the mobility of the nucleus due to diffusion and MTs pushing at the cell membrane to experiment, we estimate the viscosity governing the drag force on nuclei during positioning. A force balance model of mitotic SPB mobility compared to experimental mobility suggests that even one or two dynein dimers are sufficient to move the nucleus in the bud neck. Using stochastic computer simulations of a budding cell, we find that punctate dynein localization can generate sufficient force to reel in the nucleus to the bud neck. Compared to uniform motor localization, puncta involve fewer motors suggesting a functional role for motor clustering. Stochastic simulations also suggest that a higher number of force generators than predicted by force balance may be required to ensure the robustness of spindle positioning.
Integral and differential approaches to Eringen's nonlocal elasticity models accounting for boundary effects with applications to beams in bending
Authors: Pisano Aurora Angela , Fuschi Paolo , Polizzotto Castrenze
Published: February 2021

The Eringen's fully nonlocal elasticity model is known to lead to ill‐posed boundary‐value problems and to suffer some boundary effects arising from particle interactions impeded by the body's boundary surface. An enhanced model is derived from the original fully nonlocal one by the addition of a regularizing non‐homogeneous local phase which accounts for boundary effects and which leads to a Fredholm integral equation of the second kind, hence to well‐posed boundary‐value problems, without paradoxes, nor other drawbacks. The enhanced integral model applied to a beam in bending proves to be equivalent to a sixth order differential equation with variable coefficients, with extra nonlocality boundary conditions here also derived. Both the integral approach and the differential one lead to a same unique solution of the small‐scale beam problem. An efficient numerical algorithm is presented in which the sixth order differential equation with variable coefficients is reduced to one of the second order, which is addressed by a finite difference method. The proposed theory is applied to a set of engineering beam problems, for each of which the inherent size effects are reported and graphically illustrated. The influence of the length scale parameter upon the beam's response is highlighted by means of a function representing the normalized maximum deflection of the beam as a function of the length scale parameter. It is shown that the enhanced model always predictssoftening size effectsno matter the boundary and loading conditions, and that the related response function generally exhibits awaved pattern with positive slopes first, then negative, as the length scale parameter increases, with a limit asymptotic behavior like an atomic lattice model. A comparison with other theories is also presented together with possible future developments.
Competitive Elections, Status Anxieties, and the Relative Strength of Ethnic versus National Identification in Africa
Authors: Gadjanova Elena
Published: February 2021

Research shows that ethnic identification increases on the eve of competitive elections in Africa, but does it do so at the expense of national solidarities? Do competitive elections exacerbate the negative expressions of strong ethnic attachments-coethnic favoritism, relative status concerns, and social distance to other groups? These questions are important because the latter attitudes and perceptions are linked to a host of ills in democracies. In this paper, I examine how the proximity and competitiveness of national elections influence ingroup favoritism, ethnic groups’ status anxieties, perceived discrimination, and trust in Sub-Saharan Africa. Drawing on six rounds of survey data for seventeen countries over 14 years, I find that national identities diminish in salience relative to ethnic ones as political competition increases, and that this is accompanied by heightened perceptions of ethnically-motivated discrimination, increased status anxieties, and lower levels of both inter-ethnic and generalized trust closer to nationally-competitive elections. Therefore, the electoral cycle strongly influences group anxieties in plural societies where political competition is high, and should be taken into account when designing measures to mitigate ethnic polarization in multi-ethnic states.
Investigating the association between publication performance and the work environment of university research academics: a systematic review
Authors: Aboagye Emmanuel , Jensen Irene , Bergström Gunnar , Brämberg Elisabeth Björk , Pico-Espinosa Oscar Javier , Björklund Christina
Published: February 2021

The purpose of this review was to investigate the association between publication performance and the organizational and psychosocial work environment of academics in a university setting. In 2018 we conducted database searches in Web of Science, Medline and other key journals (hand-searched) from 1990 to 2017 based on population, exposure and outcome framework. We examined reference lists, and after a title and abstract scan and full-text reading we identified studies that were original research and fulfilled our inclusion criteria. Articles were evaluated as having a low, moderate or high risk of bias using a quality assessment form. From the studies (n= 32) identified and synthesized, work-environment characteristics could explain the quality and quantity aspects of publication performance of academics. Management practices, leadership and psychosocial characteristics are influential factors that affect academics’ publication productivity. Most of the reviewed studies were judged to be of moderate quality because of issues of bias, related to the measuring of publication outcome. The findings in the studies reviewed suggest that highly productive research academics and departments significantly tend to be influenced by the organizational and psychosocial characteristics of their working environment. The practical relevance of this review is that it highlights where academics’ performance needs support and how the work environment can be improved to bolster publication productivity.
The imaginary carrot: no correlation between raising funds and research productivity in geosciences
Authors: Mariethoz Gregoire , Herman Frédéric , Dreiss Amelie
Published: February 2021

The ability of researchers to raise funding is central to academic achievement. However, whether success in obtaining research funds correlates with the productivity, quality or impact of a researcher is debated. Here we analyse 10 years of grant funding by the Swiss National Science Foundation in Earth and Environmental Sciences, and compare it to the publication record of the researchers who were awarded the funds. No significant statistical correlation can be established between the publication or citation record of a researcher and the amount of money this researcher obtains in grant funding. These results imply that researchers successful in raising funds are not necessarily in a position to be more productive or produce more impactful publications. Those results should be considered for deciding whether to use grant funding as a criterion for career advancement procedures.
Multilingual author matching across different academic databases: a case study on KAKEN, DBLP, and PubMed
Authors: Chikazawa Yuto , Katsurai Marie , Ohmukai Ikki
Published: February 2021

Researchers often use their native languages to present and exchange ideas. To construct an individual author’s complete profile, a list of their English and non-English academic publications must be constructed. This paper presents a practical approach for multilingual author matching across different academic databases. Our approach automatically links the academic records of a target database to a researcher identifier of a source database. First, we extracted a comprehensive set of records in the target database, whose author names were identical to the researcher names in the source database. Then, we calculated multiple author similarity measures, which can be adopted in certain entity pairs from different language databases. Finally, we aggregated the measures to output an improved score that indicates the likelihood of each record as being the researcher’s work. Our method was found to be easy to implement, and its performance was evaluated in real database management settings. Experiments were conducted using DBLP and PubMed as the target English databases. As the Japanese database, KAKEN was the source for identifying researcher information. The results demonstrated each similarity measure’s performance, from which we observed that the score aggregation achieved stable performance. Our method can lessen human efforts to associate various scholarly contributions.
Graphene transfer methods: A review
Authors: Ullah Sami , Yang Xiaoqin , Ta Huy Q. , Hasan Maria , Bachmatiuk Alicja , Tokarska Klaudia , Trzebicka Barbara , Fu Lei , Rummeli Mark H.
Published: February 2021

Graphene is a material with unique properties that can be exploited in electronics, catalysis, energy, and bio-related fields. Although, for maximal utilization of this material, high-quality graphene is required at both the growth process and after transfer of the graphene film to the application-compatible substrate. Chemical vapor deposition (CVD) is an important method for growing high-quality graphene on non-technological substrates (as, metal substrates, e.g., copper foil). Thus, there are also considerable efforts toward the efficient and non-damaging transfer of quality of graphene on to technologically relevant materials and systems. In this review article, a range of graphene current transfer techniques are reviewed from the standpoint of their impact on contamination control and structural integrity preservation of the as-produced graphene. In addition, their scalability, cost- and time-effectiveness are discussed. We summarize with a perspective on the transfer challenges, alternative options and future developments toward graphene technology.
Dense ceramics with complex shape fabricated by 3D printing: A review
Authors: Chen Zhe , Sun Xiaohong , Shang Yunpeng , Xiong Kunzhou , Xu Zhongkai , Guo Ruisong , Cai Shu , Zheng Chunming
Published: February 2021

Three-dimensional (3D) printing technology is becoming a promising method for fabricating highly complex ceramics owing to the arbitrary design and the infinite combination of materials. Insufficient density is one of the main problems with 3D printed ceramics, but concentrated descriptions of making dense ceramics are scarce. This review specifically introduces the principles of the four 3D printing technologies and focuses on the parameters of each technology that affect the densification of 3D printed ceramics, such as the performance of raw materials and the interaction between energy and materials. The technical challenges and suggestions about how to achieve higher ceramic density are presented subsequently. The goal of the presented work is to comprehend the roles of critical parameters in the subsequent 3D printing process to prepare dense ceramics that can meet the practical applications.
The Pohozaev-Schoen identity on asymptotically Euclidean manifolds: Conservation laws and their applications
Authors: Avalos R. , Freitas A.
Published: February 2021

The aim of this paper is to present a version of the generalized Pohozaev-Schoen identity in the context of asymptotically Euclidean manifolds. Since these kind of geometric identities have proven to be a very powerful tool when analysing different geometric problems for compact manifolds, we will present a variety of applications within this new context. Among these applications, we will show some rigidity results for asymptotically Euclidean Ricci-solitons and Codazzi-solitons. Also, we will present an almost-Schur type inequality valid in this non-compact setting which does not need restrictions on the Ricci curvature. Finally, we will show how some rigidity results related with static potentials also follow from these type of conservation principles.
Polyhomogénéité des métriques compatibles avec une structure de Lie à l'infini le long du flot de Ricci
Authors: Ammar Mahdi
Published: February 2021

Le long du flot de Ricci, on étudie la polyhomogénéité des métriques pour des variétés riemanniennes non-compactes ayant « une structure de Lie fibrée à l'infini », c'est-à-dire une classe de structures de Lie à l'infini qui induit dans un sens précis des structures de fibrés sur les bords d'une certaine compactification par une variété à coins. Lorsque cette compactification est une variété à bord, cette classe de métriques contient notamment les b-métriques de Melrose, les métriques à bord fibré de Mazzeo-Melrose et les métriques edge de Mazzeo. On montre alors que la polyhomogénéité à l'infini des métriques compatibles avec une structure de Lie fibrée à l'infini est préservée localement par le flot de Ricci-DeTurck. Si la métrique initiale est asymptotiquement Einstein, on obtient la polyhomogénéité des métriques tant que le flot existe. De plus, si la métrique initiale est « lisse jusqu'au bord », alors il en sera de même pour les solutions du flot de Ricci normalisé et du flot de Ricci-DeTurck.
Global semiclassical limit from Hartree to Vlasov equation for concentrated initial data
Authors: Lafleche Laurent
Published: February 2021

We prove a quantitative and
global in time
semiclassical limit from the Hartree to the Vlasov equation in the case of a singular interaction potential in dimension

d \geq 3

, including the case of a Coulomb singularity in dimension

d = 3

. This result holds for initial data concentrated enough in the sense that some space moments are initially sufficiently small. As an intermediate result, we also obtain quantitative bounds on the space and velocity moments of even order and the asymptotic behavior of the spatial density due to dispersion effects, uniform in the Planck constant

ħ

.
The influence of Einstein's effective viscosity on sedimentation at very small particle volume fraction
Authors: Höfer Richard M. , Schubert Richard
Published: February 2021

We investigate the sedimentation of identical inertialess spherical particles in a Stokes fluid in the limit of many small particles. It is known that the presence of the particles leads to an increase of the effective viscosity of the suspension. By Einstein's formula this effect is of the order of the particle volume fraction

ϕ

. The disturbance of the fluid flow responsible for this increase of viscosity is very singular (like

\left|x\right|^{−2}

). Nevertheless, for well-prepared initial configurations and

\phi \rightarrow 0

, we show that the microscopic dynamics is approximated to order

\phi ^{2}|\mathrm{\log }⁡\phi |

by a macroscopic coupled transport-Stokes system with an effective viscosity according to Einstein's formula. We provide quantitative estimates both for convergence of the densities in the

p

-Wasserstein distance for all

p

and for the fluid velocity in Lebesgue spaces in terms of the

p

-Wasserstein distance of the initial data. Our proof is based on approximations through the method of reflections and on a generalization of a classical result on convergence to mean-field limits in the infinite Wasserstein metric by Hauray.
Vanishing viscosity limit of the 3D incompressible Oldroyd-B model
Authors: Zi Ruizhao
Published: February 2021

Consider the vanishing viscosity limit of the 3D incompressible Oldroyd-B model. It is shown that this set of equations admits a unique global solution with small analytic data uniformly in the coupling parameter

ω

close to

1

that corresponds to the inviscid case. We justify the limit from the Oldroyd-B model to the inviscid case

\omega = 1

for all time. Moreover, if the nonlinear term

g_{\alpha }(\tau ,\mathrm{∇}u)

is ignored, similar results hold without resorting to the analytic regularity.
Maternal awareness to the timing of allergenic food introduction in Saudi infants
Authors: Almutairi Ahmed M. , Aldayel Abdulaziz A. , Aldayel Abdulrahman S. , Alhussain Hamad A. , Alwehaibi Sultan A. , Almutairi Talal A.
Published: February 2021

Background:

Current guidelines recommend the introduction of allergenic foods as early as 4–6 months of age to decrease the risk of food allergy. However, caregivers' knowledge about such practices and adherence to them is ambiguous.

Objectives:

The purpose of this study was to evaluate the timing of introduction of potentially allergenic foods into children's diet and the level of maternal awareness about and degree of compliance with current recommendations.

Materials and methods:

We conducted a cross-sectional study from May 2019 to January 2020 at Imam Mohammad Ibn Saud Islamic University Medical Center, Riyadh, Saudi Arabia. Data were collected through questionnaire-based surveys, and a total of 405 mothers were enrolled in the study. The eligibility criteria included mothers of children between the ages of 12 and 36 months.

Results:

Most mothers in this study had initiated allergenic foods, and the average time of introduction was 9.84 ± 3.16 months for eggs, 14.6 ± 5.78 months for peanuts, and 13.6 ± 5.37 months for fish. Around one-quarter (n = 102, 25.2%) of the children were identified as being in the high-risk group. Most mothers did not know or disagreed that the timing of introducing allergenic foods might help in preventing food allergy, but there was no difference between the risk groups (33.8% and 26.2%, respectively). Moreover, only 18.6% and 13.2% of the high- and low-risk groups, respectively, received correct information from their health care providers (P = .004). Mothers with only one child were less likely to start eggs at an early age (odds ratio [OR] = 0.5 and P = .005). Furthermore, children at a high risk of food allergy were two times more likely to start eggs at an earlier age (OR = 2.12 and P = .003).

Conclusion:

In this study, the allergenic food feeding practices being followed for infants and young children were found to be suboptimal. Parental education level and the number of siblings were identified as potential barriers to the implementation of and adherence to recent guidelines. There is a need for corrective measures to ensure safe and appropriate feeding practices in the Saudi community.
In Their Own Best Interest. Is There a Paternalistic Case for Welfare Conditionality?
Authors: MOLANDER ANDERS , TORSVIK GAUTE
Published: February 2021

This paper examines paternalism as a justification for welfare reforms making benefits conditional on participation in activation programs. We clarify different types of what we denote ‘throffer paternalism’ – a paternalism conjoining an offer with a threat – and ask whether there is a good case for any of them. We argue that hard but non-perfectionistic paternalism provides the most promising defense for mandatory activation but conclude that it does not give a convincing justification for this type of welfare policy.
‘PARALLEL PROPORTIONS’ IN J. S. BACH'S MUSIC
Authors: MELAMED DANIEL R.
Published: February 2021

Recent studies propose that J. S. Bach established ‘parallel proportions’ in his music – ratios of the lengths of movements or of pieces in a collection intended to reflect the perfection of divine creation. Before we assign meaning to the number of bars in a work, we need to understand the mathematical and musical basis of the claim.

First we need to decide what a ‘bar’ is and what constitutes a ‘movement’. We have explicit evidence from Bach on these points for Bach's 1733 Dresden Missa, and his own tallies do not agree with those in the theory. There are many ways to count, and the numbers of movements or bars are analytical results dependent on choices by the analyst, not objective data.

Next, chance turns out to play an enormous role in ‘parallel proportions’. Under certain constraints almost any set of random numbers that adds up to an even total can be partitioned to show a proportion, with likelihoods better than ninety-five per cent in sets that resemble the Missa. These relationships are properties of numbers, not musical works. We thus need to ask whether any apparent proportion is the result of Bach's design or is simply a statistically inevitable result, and the answer is clearly the latter. For pieces or sets with fewer movements the odds are less overwhelming, but the subjective nature of counting and the possibility of silently choosing from among many possibilities make even these results questionable.

Theories about the number of bars in Bach's music and possible meanings are interpretative, not factual, and thus resistant to absolute disproof. But a mathematical result of the kind claimed for ‘parallel proportions’ is essentially assured even for random sets of numbers, and that makes it all but impossible to label such relationships as intentional and meaningful.
THE EARLY HISTORY OF THE CELLO IN NAPLES: GIOVANNI BONONCINI, ROCCO GRECO AND GAETANO FRANCONE IN A FORGOTTEN MANUSCRIPT COLLECTION
Authors: OLIVIERI GUIDO
Published: February 2021

The analysis of a forgotten source sheds light on the early history of the cello in seventeenth-century Naples. The manuscript MS 2-D-13, held in the library of the Montecassino Abbey, dates from around 1699 and contains two unknown cello sonatas by Giovanni Bononcini, together with passacaglias, sonatas for two ‘violas’ and elaborations over antiphons by Gaetano Francone and Rocco Greco, two prominent string performers and teachers in Naples. A study of this remarkable source helps to clarify the nomenclature of the bass violins in use in the city and offers new evidence on the practice of continuo realization at the cello, as well as on the connections with partimento practice. This collection is thus of critical importance for a discussion of the technical achievements and developments of the cello repertory in Naples before the emergence of the celebrated generation of Neapolitan cello virtuosi in the early years of the eighteenth century.
‘THE FAMOUS VIDAL’: NEW LIGHT ON THE LIFE AND WORKS OF A GUITARIST IN LATE EIGHTEENTH-CENTURY FRANCE
Authors: MARTÍN GIL DAMIÁN
Published: February 2021

During the second half of the eighteenth century the Spanish guitar reached a level of popularity in France not equalled elsewhere. Among the various composers who contributed to the vogue for the instrument in this country, sources of the period refer to a certain Mr Vidal, a guitarist of Spanish origins who was regarded as one of the most important masters of the guitar in Europe. Despite multiple references to his musical activities no extensive study has yet been made, which leaves this figure only partially studied. In order to address this lacuna, this article reconstructs the life of this guitarist, placing his music in the environment in which he lived in order to obtain a clearer picture of the situation of the guitar and the role of Vidal as a composer, guitarist, publisher and teacher.
Intraseasonal Variations in Atmospheric and Oceanic Excitation of Length‐of‐Day
Authors: Yu Nan , Ray Jim , Li Jiancheng , Chen Gang , Chao Nengfang , Chen Wei
Published: February 2021

Like the seasonal and interannual variations in length‐of‐day (LOD), variations on intraseasonal timescales (periods shorter than 183 days) are also predominantly caused by changes in the angular momentum of the zonal winds. But the smaller intraseasonal LOD excitations from atmospheric surface pressure, oceanic currents, and the ocean bottom pressure are less clear. Here sliding window average filtering is applied to isolate intraseasonal signals from both geodetically observed LOD excitation (shorten to geodetic excitation for convenience) and atmospheric and oceanic LOD excitations. Based on careful comparison between these two‐excitation series, we find that during 1993–2018, atmospheric winds reduce the RMS of observed intraseasonal LOD series from 276.1 to 55.6 μs with a correlation coefficient of 0.9795. Including the effect of surface pressure changes with that of the winds reduced the RMS from 55.6 to 43.3 μs, and increased the correlation coefficient with the observations from 0.9795 to 0.9884. Additionally, including the effects of changes in oceanic currents and bottom pressure further reduced the RMS from 43.3 to 33.9 μs, and further increased the correlation coefficient from 0.9884 to 0.9931. Thus, although the impact of oceans is relatively minor, closer agreement with the observations in the intraseasonal frequency band is obtained when the effects of oceanic processes are added to that of atmospheric. The RMS values and correlation coefficients of ESMGFZ and MPIOM residual series are better than NCEP and ECCO in every component, indicating that NCEP model set is generally poorer than ESMGFZ in the intraseasonal band.
Solar or Diesel: A Comparison of Costs for Groundwater‐Fed Irrigation in Sub‐Saharan Africa Under Two Energy Solutions
Authors: Xie Hua , Ringler Claudia , Mondal Md. Alam Hossain
Published: February 2021

Sub‐Saharan Africa has long been beset with food insecurity and energy poverty. Expanding irrigated agriculture can help boost food production in the region, but this requires energy for accessing water, especially in groundwater‐fed irrigation. This paper compared economic performance of groundwater pumping for irrigation under two energy solutions: solar photovoltaic (PV) and diesel fuel. We estimated the life‐cycle costs of the power units of two pumping systems for a range of crop and irrigation method scenarios and mapped their relative cost‐effectiveness over cropland in sub‐Saharan Africa. As a renewable and clean energy source, solar energy has attracted much attention and there is keen interest in investing in solar PV to support the development of irrigated agriculture. Results of this study provide insights into the prospects of promoting solar irrigation in sub‐Saharan Africa.
Potential Influences of Volcanic Eruptions on Future Global Land Monsoon Precipitation Changes
Authors: Man Wenmin , Zuo Meng , Zhou Tianjun , Fasullo John T. , Bethke Ingo , Chen Xiaolong , Zou Liwei , Wu Bo
Published: February 2021

The global monsoon system is of exceptional socioeconomic importance owing to its impacts on two‐thirds of the globe’s population. Major volcanic eruptions strongly influence global land monsoon (GLM) precipitation change. By using 60 plausible eruption scenarios sampled from reconstructed volcanic proxies over the past 2,500 years, 21st century volcanic influences on GLM precipitation projections are examined with an Earth system model under a moderate emission scenario. The decadal‐scale ensemble spread with realistic eruptions (VOLC) increases by 17.5% and 20.1% compared to no‐volcanic (NO‐VOLC) and constant background‐volcanic (VOLC‐CONST) scenarios, respectively. Compared with NO‐VOLC, the centennial mean VOLC GLM precipitation shows a 10% overall reduction and regionally, Asia is the most impacted. Changes in atmospheric circulation in the aftermath of large volcanic eruptions match the global warming response patterns well with opposite sign, with the North American monsoon precipitation enhanced following large volcanic eruptions, which is in sharp contrast to the robust decrease in Asian monsoon rainfall. Volcanic activity could delay the time of emergence of anthropogenic influence by five years on average over about 60% of the GLM area. Our results demonstrate the importance of statistical representation of potential volcanism for the projections of future monsoon variability. Quantifying volcanic impacts on regional climate projections and their socioeconomic influences on infrastructure planning, food security, and disaster management should be a priority of future work.
Comparing Patterns of Hurricane Washover into Built and Unbuilt Environments
Authors: Lazarus Eli D. , Goldstein Evan B. , Taylor Luke A. , Williams Hannah E.
Published: February 2021

Extreme geohazard events can change landscape morphology by redistributing huge volumes of sediment. Event‐driven sediment deposition is typically studied in unbuilt settings – despite the ubiquity of occurrence and high economic cost of these geohazard impacts in built environments. Moreover, sedimentary consequences of extreme events in built settings tend to go unrecorded because they are rapidly cleared, at significant expense, from streets and roads to facilitate emergency response. Reducing disaster costs requires an ability to predict disaster impacts, which itself requires comprehensive measurement and study of the physical consequences of geohazard events. Here, using a database of poststorm aerial imagery, we measure plan‐view geometric characteristics of sandy washover deposits in built and unbuilt settings following five different hurricane strikes along the Atlantic and Gulf Coasts of the US since 2011. We identify systematic similarities and differences between washover morphology in built and unbuilt environments, which we further explore with a simplified numerical model. Our findings suggest that spatial characteristics of the built environment (termed “fabric”) – specifically, the built fraction of the depositional zone – exerts a fundamental control on the form of large deposits. Accounting for the influence of built fabric on the morphodynamics of flow‐driven geohazards is a tractable step toward improved forecasts of hazard impacts and disaster risk reduction.
Assessing the Impact of Wildfires on the Use of Black Carbon as an Indicator of Traffic Exposures in Environmental Epidemiology Studies
Authors: Martenies S. E. , Hoskovec L. , Wilson A. , Allshouse W. B. , Adgate J. L. , Dabelea D. , Jathar S. , Magzamen S.
Published: February 2021

Epidemiological studies frequently use black carbon (BC) as a proxy for traffic‐related air pollution (TRAP). However, wildfire smoke (WFS) represents an important source of BC not often considered when using BC as a proxy for TRAP. Here, we examined the potential for WFS to bias TRAP exposure assessments based on BC measurements. Weekly integrated BC samples were collected across the Denver, CO region from May to November 2018. We collected 609 filters during our sampling campaigns, 35% of which were WFS‐impacted. For each filter we calculated an average BC concentration. We assessed three GIS‐based indicators of TRAP for each sampling location: annual average daily traffic within a 300 m buffer, the minimum distance to a highway, and the sum of the lengths of roadways within 300 m. Median BC concentrations were 9% higher for WFS‐impacted filters (median = 1.14 μg/m3, IQR = 0.23 μg/m3) than nonimpacted filters (median = 1.04 μg/m3, IQR = 0.48 μg/m3). During WFS events, BC concentrations were elevated and expected spatial gradients in BC were reduced. We conducted a simulation study to estimate TRAP exposure misclassification as the result of regional WFS. Our results suggest that linear health effect estimates were biased away from the null when WFS was present. Thus, exposure assessments relying on BC as a proxy for TRAP may be biased by wildfire events. Alternative metrics that account for the influence of “brown” carbon associated with biomass burning may better isolate the effects of traffic emissions from those of other black carbon sources.
Real‐Time Earthquake Early Warning With Deep Learning: Application to the 2016 M 6.0 Central Apennines, Italy Earthquake
Authors: Zhang Xiong , Zhang Miao , Tian Xiao
Published: February 2021

Earthquake early warning (EEW) systems are required to report earthquake locations and magnitudes as quickly as possible before the damaging S wave arrival to mitigate seismic hazards. Deep learning techniques provide potential for extracting earthquake source information from full seismic waveforms instead of seismic phase picks. We developed a novel deep learning EEW system that utilizes fully convolutional networks to simultaneously detect earthquakes and estimate their source parameters from continuous seismic waveform streams. The system determines earthquake location and magnitude as soon as very few stations receive earthquake signals and evolutionarily improves the solutions by receiving continuous data. We apply the system to the 2016 M 6.0 Central Apennines, Italy Earthquake and its first‐week aftershocks. Earthquake locations and magnitudes can be reliably determined as early as 4 s after the earliest P phase, with mean error ranges of 8.5–4.7 km and 0.33–0.27, respectively.
Classifying Oceanographic Structures in the Amundsen Sea, Antarctica
Authors: Boehme Lars , Rosso Isabella
Published: February 2021

The remote and often ice‐covered Amundsen Sea Embayment in Antarctica is important for transporting relatively warm modified Circumpolar Deep Water (mCDW) to the Western Antarctic Ice Sheet, potentially accelerating its thinning and contribution to sea level rise. To investigate potential pathways and variability of mCDW, 3809 CTD profiles (instrumented seal and ship‐based data) are classified using a machine learning approach (Profile Classification Model). Five vertical regimes are identified, and areas of larger variability highlighted. Three spatial regimes are captured: Off‐Shelf, Eastern and Central Troughs. The on‐shelf profiles further show a separation between cold and warm modes. The variability is higher north of Burke Island and at the southern end of the Eastern Trough, which reflects the convergence of different mCDW pathways between the Eastern and the Central Trough. Finally, a clear but variable clockwise circulation is identified in Pine Island Bay.
Atmospheric River Precipitation Contributed to Rapid Increases in Surface Height of the West Antarctic Ice Sheet in 2019
Authors: Adusumilli Susheel , A. Fish Meredith , Fricker Helen Amanda , Medley Brooke
Published: February 2021

Estimating the relative contributions of the atmospheric and dynamic components of ice‐sheet mass balance is critical for improving projections of future sea level rise. Existing estimates of changes in Antarctic ice‐sheet height, which can be used to infer changes in mass, are only accurate at multiyear time scales. However, NASA's Ice, Cloud, and land Elevation Satellite‐2 (ICESat‐2) laser altimetry mission now allows us to accurately measure changes in ice‐sheet height at subannual time scales. Here, we use ICESat‐2 data to estimate height changes over Antarctica between April 2019 and June 2020. These data show widespread increases in surface height over West Antarctica during the 2019 austral winter. Using climate reanalysis data, we show that 41% of increases in height during winter were from snow accumulation via extreme precipitation events—63% of these events were associated with landfalling atmospheric rivers (ARs) which occurred only 5.1% of the time.
Periodic Rising and Falling Tone ECH Waves From Van Allen Probes Observations
Authors: Shen Xiao‐Chen , Li Wen , Ma Qianli
Published: February 2021

Electron cyclotron harmonic (ECH) waves are known to precipitate plasma sheet electrons into the upper atmosphere and generate diffuse aurorae. In this study, we report quasiperiodic rising (3 events) and falling tone (22 events) ECH waves observed by Van Allen Probes and evaluate their properties. These rising and falling tone ECH waves prefer to occur during quiet geomagnetic conditions over the dusk to midnight sector in relatively high‐density (10–80 cm−3) regions. Their repetition periods increase with increasing L shell at L < 6, ranging from ∼60 to 110 s. The wave element duration varies from 10 to 130 s peaking at ∼40 s and the chirping rate peaks at ∼50 (∼−50) Hz/s for rising (falling) tones. Our findings reveal intriguing features of the ECH wave properties, which provide new insights into their generation and potential effects on electron precipitation.
Arctic Ozone Depletion in 2019/20: Roles of Chemistry, Dynamics and the Montreal Protocol
Authors: Feng Wuhu , Dhomse Sandip S. , Arosio Carlo , Weber Mark , Burrows John P. , Santee Michelle L. , Chipperfield Martyn P.
Published: February 2021

We use a three‐dimensional chemical transport model and satellite observations to investigate Arctic ozone depletion in winter/spring 2019/20 and compare with earlier years. Persistently, low temperatures caused extensive chlorine activation through to March. March‐mean polar‐cap‐mean modeled chemical column ozone loss reached 78 DU (local maximum loss of ∼108 DU in the vortex), similar to that in 2011. However, weak dynamical replenishment of only 59 DU from December to March was key to producing very low (<220 DU) column ozone values. The only other winter to exhibit such weak transport in the past 20 years was 2010/11, so this process is fundamental to causing such low ozone values. A model simulation with peak observed stratospheric total chlorine and bromine loading (from the mid‐1990s) shows that gradual recovery of the ozone layer over the past 2 decades ameliorated the polar cap ozone depletion in March 2020 by ∼20 DU.
Projecting Global Mean Sea‐Level Change Using CMIP6 Models
Authors: Hermans Tim H. J. , Gregory Jonathan M. , Palmer Matthew D. , Ringer Mark A. , Katsman Caroline A. , Slangen Aimée B. A.
Published: February 2021

The effective climate sensitivity (EffCS) of models in the Coupled Model Intercomparison Project 6 (CMIP6) has increased relative to CMIP5. We explore the implications of this for global mean sea‐level (GMSL) change projections in 2100 for three emissions scenarios. CMIP6 projections of global surface air temperature are substantially higher than in CMIP5, but projections of global mean thermal expansion are not. Using these projections as input to construct projections of GMSL change with IPCC AR5 methods, the 95th percentile of GMSL change at 2100 only increases by 3–7 cm. Projected rates of GMSL rise around 2100 increase more strongly, though, implying more pronounced differences beyond 2100 and greater committed sea‐level rise. Intermodel differences in GMSL projections indicate that EffCS‐based model selection may substantially alter the ensemble projections. GMSL change in 2100 is accurately predicted by time‐integrated temperature change, and thus requires reducing emissions early to be mitigated.
F Region Electric Field Effects on the Intermediate Layer Dynamics During the Evening Prereversal Enhancement at Equatorial Region Over Brazil
Authors: Santos A. M. , Batista I. S. , Brum C. G. M. , Sobral J.H.A. , Abdu M. A. , Souza J. R.
Published: February 2021

Using ionograms from the Brazilian equatorial site of São Luís (SL, 2° S; 44° W, I = −3.8°), the relationship between the uplift of the intermediate layers (ILs) at sunset and the prereversal enhancement of the zonal electric field (PRE) is investigated. The ILs were studied during the solar maximum (2003) and minimum activity (2009) periods. The presence of the ILs during the PRE occurrence time was very low during both years. In 2003, six ILs’ events were observed, being four of them in the summer solstice and one in the March equinox. In 2009, only a single event was registered and occurred during the December month. The results show that depending on the height at which the ILs are located, their upward movement at sunset can be in some way related to the normal F layer rise at sunset due to the PRE. The initial altitude at which such ascending ILs were observed was higher than their normal height near sunset. Additionally, the eastward prompt penetration electric fields (PPEFs) during weak magnetic storms can also contribute to the IL’s rise. An interesting case of uplift of a sporadic‐E layer from ∼120 to 290 km probably due to the PPEF is also investigated.
Modeling of the Lower Ionosphere During Solar X‐Ray Flares of Different Classes
Authors: Bekker S. Z. , Ryakhovsky I. A. , Korsunskaya J. A.
Published: February 2021

This study presents the results obtained from modeling the lower ionosphere response to C‐, M‐ and X‐class solar X‐ray flares. This model is based on a 5‐component scheme for the ionization‐recombination cycle of the ionospheric D‐region. Input parameters for the plasma‐chemical model under different heliogeophysical conditions corresponding to selected X‐ray flares were determined by using data received from the AURA, SDO, and GOES satellites. Verification of the obtained results was carried out with use of ground‐based radiophysical measurements taken at the geophysical observatory Mikhnevo. The results obtained from a comparison of the calculated and experimental radio wave amplitude variations along six European very low frequency (VLF) paths show that the average normalized root mean square error is ∼7%, 14%, and 18% for C‐, M‐, and X‐class flares, respectively. Qualitative and quantitative analysis of the verification results for the VLF signal amplitude show good predictive capability of the model built for describing weak and moderate ionospheric disturbances.