bluuebunny/crossref_metadata_2025 huggingface dataset:
Propagation of singularities for generalized solutions to nonlinear wave equations
Authors: Deguchi Hideo , Oberguggenberger Michael
Published: July 2020

The paper is devoted to regularity theory of generalized solutions to semilinear wave equations with a small nonlinearity. The setting is the one of Colombeau algebras of generalized functions. It is shown that in one space dimension, an initial singularity at the origin propagates along the characteristic lines emanating from the origin, as in the linear case. The proof is based on a fixed point theorem in a suitable ultrametric topology on the subset of Colombeau solutions possessing the required regularity. The paper takes up the initiating research of the 1970s on anomalous singularities in classical solutions to semilinear hyperbolic equations, and shows that the same behavior is attained in the case of non-classical, generalized solutions.
Is There a Governing Role of Osteocytes in Bone Tissue Regeneration?
Authors: Cao Wei , Helder Marco N. , Bravenboer Nathalie , Wu Gang , Jin Jianfeng , ten Bruggenkate Christiaan M. , Klein-Nulend Jenneke , Schulten Engelbert A. J. M.
Published: July 2020

Purpose of Review

Bone regeneration plays an important role in contemporary clinical treatment. Bone tissue engineering should result in successful bone regeneration to restore congenital or acquired bone defects in the human skeleton. Osteocytes are thought to have a governing role in bone remodeling by regulating osteoclast and osteoblast activity, and thus bone loss and formation. In this review, we address the so far largely unknown role osteocytes may play in bone tissue regeneration.

Recent Findings

Osteocytes release biochemical signaling molecules involved in bone remodeling such as prostaglandins, nitric oxide, Wnts, and insulin-like growth factor-1 (IGF-1). Treatment of mesenchymal stem cells in bone tissue engineering with prostaglandins (e.g., PGE2, PGI2, PGF2α), nitric oxide, IGF-1, or Wnts (e.g., Wnt3a) improves osteogenesis.

This review provides an overview of the functions of osteocytes in bone tissue, their interaction with other bone cells, and their role in bone remodeling. We postulate that osteocytes may have a pivotal role in bone regeneration as well, and consequently that the bone regeneration process may be improved effectively and rapidly if osteocytes are optimally used and stimulated.
High-Performance Aqueous Zinc-Ion Batteries Realized by MOF Materials
Authors: Pu Xuechao , Jiang Baozheng , Wang Xianli , Liu Wenbao , Dong Liubing , Kang Feiyu , Xu Chengjun
Published: July 2020

Rechargeable aqueous zinc-ion batteries (ZIBs) have been gaining increasing interest for large-scale energy storage applications due to their high safety, good rate capability, and low cost. However, the further development of ZIBs is impeded by two main challenges: Currently reported cathode materials usually suffer from rapid capacity fading or high toxicity, and meanwhile, unstable zinc stripping/plating on Zn anode seriously shortens the cycling life of ZIBs. In this paper, metal–organic framework (MOF) materials are proposed to simultaneously address these issues and realize high-performance ZIBs with Mn(BTC) MOF cathodes and ZIF-8-coated Zn (ZIF-8@Zn) anodes. Various MOF materials were synthesized, and Mn(BTC) MOF was found to exhibit the best Zn2+-storage ability with a capacity of 112 mAh g−1. Zn2+ storage mechanism of the Mn(BTC) was carefully studied. Besides, ZIF-8@Zn anodes were prepared by coating ZIF-8 MOF material on Zn foils. Unique porous structure of the ZIF-8 coating guided uniform Zn stripping/plating on the surface of Zn anodes. As a result, the ZIF-8@Zn anodes exhibited stable Zn stripping/plating behaviors, with 8 times longer cycle life than bare Zn foils. Based on the above, high-performance aqueous ZIBs were constructed using the Mn(BTC) cathodes and the ZIF-8@Zn anodes, which displayed an excellent long-cycling stability without obvious capacity fading after 900 charge/discharge cycles. This work provides a new opportunity for high-performance energy storage system.
The Making of the Indo-Islamic World
Authors: Wink André
Published: July 2020

In a new accessible narrative, Andre Wink presents his major reinterpretation of the long-term history of India and the Indian Ocean region from the perspective of world history and geography. Situating the history of the Indianized territories of South Asia and Southeast Asia within the wider history of the Islamic world, he argues that the long-term development and transformation of Indo-Islamic history is best understood as the outcome of a major shift in the relationship between the sedentary peasant societies of the river plains, the nomads of the great Saharasian arid zone and the seafaring populations of the Indian Ocean. This revisionist work redraws the Asian past as the outcome of the fusion of these different types of settled and mobile societies, placing geography and environment at the centre of human history.
Die Linke v. Federal Government and Federal Parliament (Counter Daesh)
Authors: Tams Christian J.
Published: July 2020

By a September 17, 2019 Order (Order), the German Federal Constitutional Court (FCC or Court) rejected challenges to Germany's military involvement in anti-Islamic State of Iraq and Syria (ISIS) operations in Syria. This outcome was expected and was as such insignificant. What is significant is the FCC's reasoning. The Court used the Order to clarify the constitutional roles of parliament and the executive in German foreign affairs. And it included an intriguing pronouncement on the scope of Article 51 of the UN Charter, which adds a fresh perspective to the polarized debates about self-defense against nonstate actors.
The State of the Netherlands v. Respondents & Stichting Mothers of Srebrenica
Authors: Boon Kristen
Published: July 2020

The July 2019 decision of the Supreme Court of the Netherlands constitutes the final act of a long litigation arising from the July 1995 genocide in Srebrenica. After Bosnian Serb militias attacked the safe area of Srebrenica, members of the Dutch battalion (Dutchbat), which was responsible for safeguarding the enclave under a UN mandate, permitted between 8,000 and 10,000 men and boys to be taken away by Bosnian Serb forces. Those men and boys were eventually killed by forces commanded by General Ratko Mladić and Radovan Karadžić, president of the autonomous Republika Srpska. This Supreme Court decision and related rulings involve issues of international responsibility for the conduct of peacekeepers—in particular, attribution of conduct to the United Nations and its member states and immunity of international organizations.
Behavioral public strategy
Authors: GEORGE BERT
Published: July 2020

How can we stimulate policymakers to make strategic decisions that enhance public service performance? Traditional strategy theories have not enabled us to answer this question. These theories focus on strategy processes or content in public organizations and networks and directly link these to public service performance. This article defines and elaborates on a conceptual framework that uses theory from behavioral science to unravel how policymakers can make strategic decisions that actually enhance the performance of public organizations and networks. This conceptual framework is labeled ‘behavioral public strategy’ and conceptualizes public strategy as a social process shaped by the individuals, teams and tools underlying it. Behavioral public strategy thus focuses on the micro-foundations of public strategy and how these micro-foundations influence strategic decisions. Moreover, behavioral public strategy links meso- and micro-levels by proposing a bathtub model where the relationship between public strategy and public service performance at the organizational and network levels is explained by the relationship between the micro-foundations of public strategy and the ensuing strategic decisions at the individual and team levels. This article connects three research streams that have been like ‘ships that pass in the night’, namely public strategy, behavioral public policy and behavioral public administration.
Effectiveness and Recommendations for the Use of Dental Masks in the Prevention of COVID-19: A Literature Review
Authors: Arellano-Cotrina Josabet Johana , Marengo-Coronel Nicole , Atoche-Socola Katherine Joselyn , Peña-Soto Claudio , Arriola-Guillén Luis Ernesto
Published: July 2020

The purpose of this investigation was to identify, synthesize, and compare all the current information on the efficacy of dental masks, emphasizing their use, types, and filters to prevent the spread and infection of COVID-19 and other infectious diseases. A bibliographic search of the main scientific databases was carried out using the words “masks, COVID-19, and dentistry.” Articles without language restriction up to May 31, 2020, were obtained. The types of masks, their half-life, method to use, sterilization, and proposed alternatives for dental masks were analyzed. Most of the articles refer to the use of N95 or FFP2 respirators presented as a strategy to extend the life of the masks and limited reuse. Regarding sterilization, most of the articles presented studies using ultraviolet germicidal irradiation as the sterilization method. Regarding respirator mask half-life, we recommend prolonged use, combined with a disposable surgical mask over the respirator mask. Finally, the use of N95 or FFP2 respirators are recommended as part of personal protective equipment for dental use.
Substituting chemical fertilizer nitrogen with organic manure and comparing their nitrogen use efficiency and winter wheat yield
Authors: Yang Y. J. , Lei T. , Du W. , Liang C. L. , Li H. D. , Lv J. L.
Published: July 2020

A 2-year fertilization experiment was conducted to study the effect of different ratios of organic (pig) manure on wheat yield and nitrogen use efficiency (NUE). The four treatments were no nitrogen (N) (CK); 100% chemical fertilizer N (urea; T1); 70% chemical fertilizer N + 30% organic manure N (T2) and 50% chemical fertilizer N + 50% organic manure N (T3), with the same amount of applied nitrogen (120 kg/ha). The results showed the maximum grain yield (3049 kg/ha), crop nitrogen uptake (216 kg/ha), NUE (65.4%) and accumulated nitrate nitrogen (NO3−-N in 0–200 cm, 142 kg/ha) were observed in the T1 among all treatments in the first year. However, the largest grain yield (5074 kg/ha), crop nitrogen uptake (244 kg/ha) and NUE (82.5%) were under T2 treatment in the second year. Furthermore, T2 had the maximum NO3−-N content in 0–100 cm layer (116 kg/ha), especially 0–40 cm layer, and the lowest NO3−-N content in 100–200 cm (58.8 kg/ha). However, 50% organic manure N in T3 increased apparent nitrogen loss by 39.0% compared to that in T2. Therefore, 30% organic manure N application was more conducive for enhancing wheat yield and NUE and promoting environmental safety after 1-year fertilization time.
Online psychological interventions to reduce symptoms of depression, anxiety, and general distress in those with chronic health conditions: a systematic review and meta-analysis of randomized controlled trials
Authors: White V. , Linardon J. , Stone J. E. , Holmes-Truscott E. , Olive L. , Mikocka-Walus A. , Hendrieckx C. , Evans S. , Speight J.
Published: July 2020

Background

Over the past 15 years, there has been substantial growth in web-based psychological interventions. We summarize evidence regarding the efficacy of web-based self-directed psychological interventions on depressive, anxiety and distress symptoms in people living with a chronic health condition.

Method

We searched Medline, PsycINFO, CINAHL, EMBASE databases and Cochrane Database from 1990 to 1 May 2019. English language papers of randomized controlled trials (usual care or waitlist control) of web-based psychological interventions with a primary or secondary aim to reduce anxiety, depression or distress in adults with a chronic health condition were eligible. Results were assessed using narrative synthases and random-effects meta-analyses.

Results

In total 70 eligible studies across 17 health conditions [most commonly: cancer (k= 20), chronic pain (k= 9), arthritis (k= 6) and multiple sclerosis (k= 5), diabetes (k= 4), fibromyalgia (k= 4)] were identified. Interventions were based on CBT principles in 46 (66%) studies and 42 (60%) included a facilitator. When combining all chronic health conditions, web-based interventions were more efficacious than control conditions in reducing symptoms of depressiong= 0.30 (95% CI 0.22–0.39), anxietyg= 0.19 (95% CI 0.12–0.27), and distressg= 0.36 (95% CI 0.23–0.49).

Conclusion

Evidence regarding effectiveness for specific chronic health conditions was inconsistent. While self-guided online psychological interventions may help to reduce symptoms of anxiety, depression and distress in people with chronic health conditions in general, it is unclear if these interventions are effective for specific health conditions. More high-quality evidence is needed before definite conclusions can be made.
Altered brain structural and functional connectivity in schizotypy
Authors: Wang Yong-ming , Cai Xin-lu , Zhang Rui-ting , Zhang Yi-jing , Zhou Han-yu , Wang Yi , Wang Ya , Huang Jia , Wang Yan-yu , Cheung Eric F. C. , Chan Raymond C. K.
Published: July 2020

Background

Schizotypy refers to schizophrenia-like traits below the clinical threshold in the general population. The pathological development of schizophrenia has been postulated to evolve from the initial coexistence of ‘brain disconnection’ and ‘brain connectivity compensation’ to ‘brain connectivity decompensation’.

Methods

In this study, we examined the brain connectivity changes associated with schizotypy by combining brain white matter structural connectivity, static and dynamic functional connectivity analysis of diffusion tensor imaging data and resting-state functional magnetic resonance imaging data. A total of 87 participants with a high level of schizotypal traits and 122 control participants completed the experiment. Group differences in whole-brain white matter structural connectivity probability, static mean functional connectivity strength, dynamic functional connectivity variability and stability among 264 brain sub-regions of interests were investigated.

Results

We found that individuals with high schizotypy exhibited increased structural connectivity probability within the task control network and within the default mode network; increased variability and decreased stability of functional connectivity within the default mode network and between the auditory network and the subcortical network; and decreased static mean functional connectivity strength mainly associated with the sensorimotor network, the default mode network and the task control network.

Conclusions

These findings highlight the specific changes in brain connectivity associated with schizotypy and indicate that both decompensatory and compensatory changes in structural connectivity within the default mode network and the task control network in the context of whole-brain functional disconnection may be an important neurobiological correlate in individuals with high schizotypy.
Qualities of the environment that support a sense of home and belonging in nursing homes for older people
Authors: Johansson Karin , Borell Lena , Rosenberg Lena
Published: July 2020

The aim of this study was to contribute with knowledge about how a sense of home and belonging is enacted and can be supported in everyday life, with a particular focus on the relationships that connect everyday life and the environment in nursing home contexts. The concepts ‘a sense of home’ and ‘belonging’ were chosen with the ambition to grasp values grounded in experiences and everyday practices, with an openness for various aspects that can support an enjoyable life and comfort for nursing home residents. The study focused on communal areas, e.g. dining room, kitchen, corridors and gardens, that serve as arenas where nursing home residents’ everyday lives expand beyond the private room. Ethnographic methods were applied to identify and explore situations where a sense of home and belonging were enacted in nursing homes that had been acknowledged as good examples of nursing home environments. Through the analytic process, four qualities were identified: (a) a cornerstone for stability and everydayness, (b) the beating heart, (c) spatial dynamics, and (d) magnetic places. Following from the chosen methodology, the findings provide a situated understanding of how communal areas in nursing homes can invite a sense of home and belonging for the residents.
Development of a Method for Data Dimensionality Reduction in Loop Closure Detection: An Incremental Approach
Authors: Moreira Leandro A. S. , Justel Claudia M. , de Oliveira Jauvane C. , Rosa Paulo F. F.
Published: July 2020

This article proposes a method for incremental data dimensionality reduction in loop closure detection for robotic autonomous navigation. The approach uses dominant eigenvector concept for: (a) spectral description of visual datasets and (b) representation in low dimension. Unlike most other papers on data dimensionality reduction (which is done in batch mode), our method combines a sliding window technique and coordinate transformation to achieve dimensionality reduction in incremental data. Experiments in both simulated and real scenarios were performed and the results are suitable.
EFFICIENT ESTIMATION OF INTEGRATED VOLATILITY FUNCTIONALS UNDER GENERAL VOLATILITY DYNAMICS
Authors: Li Jia , Liu Yunxiao
Published: July 2020

We provide an asymptotic theory for the estimation of a general class of smooth nonlinear integrated volatility functionals. Such functionals are broadly useful for measuring financial risk and estimating economic models using high-frequency transaction data. The theory is valid under general volatility dynamics, which accommodates both Itô semimartingales (e.g., jump-diffusions) and long-memory processes (e.g., fractional Brownian motions). We establish the semiparametric efficiency bound under a nonstandard nonergodic setting with infill asymptotics, and show that the proposed estimator attains this efficiency bound. These results on efficient estimation are further extended to a setting with irregularly sampled data.
Bidirectional associations between self-regulation and deviance from adolescence to adulthood
Authors: Billen Eva , Garofalo Carlo , Weller Joshua A. , Kirisci Levent , Reynolds Maureen , Tarter Ralph E. , Bogaerts Stefan
Published: July 2020

Self-regulation is considered a major predictor of crime and deviant behavior. However, longitudinal research investigating these associations, frequently looked only at the effect of self-regulation on deviant behavior, but not the other way around. The current study argued that deviance may contribute to later problems in self-regulation, and examined bidirectional associations, comparing a unidirectional and bidirectional model of associations between these variables. A Random Intercept Cross-Lagged Panel Model and eight data waves from 772 participants, aged 10–12 years to 30 years were used. Results showed that a bidirectional model fit the data better than a unidirectional model. The final model revealed an influence of deviance on self-regulation mainly in adolescence, whereas self-regulation influenced deviance only over two time points in adulthood. The results suggest that, in adolescence, problems in self-regulation may follow, rather than precede deviant behavior. Thus, decreasing deviant behavior or intervening in the aftermaths of deviant behavior in adolescence might have a positive effect on self-regulation in young adulthood, lowering the chance of adult deviant behavior. The current study shows that the long-presumed directionality of self-regulation to deviance can lead to bias, and more rigorous longitudinal research is needed in order to further inform theory and practice.
Prehospital Intervals and In-Hospital Trauma Mortality: A Retrospective Study from a Level I Trauma Center
Authors: Al-Thani Hassan , Mekkodathil Ahammed , Hertelendy Attila J. , Frazier Tim , Ciottone Gregory R. , El-Menyar Ayman
Published: July 2020

Background:

The increase in mortality and total prehospital time (TPT) seen in Qatar appear to be realistic. However, existing reports on the influence of TPT on mortality in trauma patients are conflicting. This study aimed to explore the impact of prehospital time on the in-hospital outcomes.

Methods:

A retrospective analysis of data on patients transferred alive by Emergency Medical Services (EMS) and admitted to Hamad Trauma Center (HTC) of Hamad General Hospital (HGH; Doha, Qatar) from June 2017 through May 2018 was conducted. This study was centered on the National Trauma Registry database. Patients were categorized based on the trauma triage activation and prehospital intervals, and comparative analysis was performed.

Results:

A total of 1,455 patients were included, of which nearly one-quarter of patients required urgent and life-saving care at a trauma center (T1 activations). The overall TPT was 70 minutes and the on-scene time (OST) was 24 minutes. When compared to T2 activations, T1 patients were more likely to have been involved in road traffic injuries (RTIs); experienced head and chest injuries; presented with higher Injury Severity Score (ISS: median = 22); and had prolonged OST (27 minutes) and reduced TPT (65 minutes; P = .001). Prolonged OST was found to be associated with higher mortality in T1 patients, whereas TPT was not associated.

Conclusions:

In-hospital mortality was independent of TPT but associated with longer OST in severely injured patients. The survival benefit may extend beyond the golden hour and may depend on the injury characteristics, prehospital, and in-hospital settings.
Associations between healthy Japanese dietary patterns and depression in Japanese women
Authors: Konishi Kanae
Published: July 2020

Objective:

Higher quality dietary patterns such as healthy/prudent and Mediterranean dietary patterns have been protectively associated with depression. This study examined whether healthy Japanese dietary patterns, which differ from dietary patterns derived from Western areas, are associated with depressive symptoms among Japanese women.

Design:

A cross-sectional study (the Nagano Nutrition and Health Study). Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale. Dietary patterns were derived with a principal component analysis of the consumption of fifty-six food and beverage items, which were assessed by a validated brief diet history questionnaire.

Setting:

Nagano, Japan.

Participants:

Japanese women (n 1337) aged 20–72 years.

Results:

We identified three dietary patterns: ‘healthy Japanese’, ‘sweets-fat’ and ‘seafood–alcohol’. The highest quality dietary pattern was ‘healthy Japanese’. It is characterised by a high intake of vegetables, mushrooms, seaweed, soyabean products, potatoes, fish/shellfish and fruit. The age- and multivariate-adjusted OR (95 % CI) of depressive symptoms for the highest quartiles of the ‘healthy Japanese’ pattern score were 0·58 (95 % CI 0·41, 0·82) and 0·69 (95 % CI 0·45, 1·06), respectively. Meanwhile, no associations were observed for ‘sweets-fat’ and ‘seafood–alcohol’ patterns.

Conclusions:

The ‘healthy Japanese’ pattern may be inversely associated with depressive symptoms with an exposure-response association. The specific Japanese food groups in the ‘healthy Japanese’ pattern included mushrooms, seaweed, soyabean products and potatoes, as well as vegetables, fish/shellfish and fruit. These seem to create an anti-inflammation-prone dietary pattern, and this factor might be associated with better mental health.
World Music Without Profit
Authors: GALLOPE MICHAEL
Published: July 2020

This article explores political and aesthetic dimensions of the ‘bubu music’ made by Sierra Leonean émigré Janka Nabay while living in the United States from 2010 to 2017. It narrates Nabay's story while tracing granular flows of creative labour, collaboration, and negotiations of cultural and economic capital at some level of ethnographic detail. The central sections of the article excavate the complex and often non-linear labour that went into the production of his band's music, and gives readers a sense of the way Nabay himself intellectually framed this process. It ultimately argues that Nabay was a resilient but often-dehumanized subject who exemplified the cultural and economic cross-currents of ‘World Music 2.0’ in ways that set privileged Western values of artistic autonomy into vivid relief. As an economically precarious subject split between indigenous nationalism and Western forms of cultural capital, Nabay lived a life of profound contradictions, by turns dissenting and exuberant.
The Gendered Impacts of COVID-19 amid Agrarian Distress: Opportunities for Comprehensive Policy Response in Agrarian South Asia
Authors: Nichols Carly E. , Jalali Falak , Ali Syed Shoaib , Gupta Divya , Shrestha Suchita , Fischer Harry
Published: July 2020

COVID-19 and its associated disease control measures have greatly altered everyday life. The burden of these challenges has fallen disproportionately on women. Drawing on qualitative inquiry in agrarian north India and Nepal, this research note analyzes how South Asian COVID-19 lockdowns have affected women's labor responsibilities in sometimes surprising ways. We find increased responsibilities for caregiving within the household, substantial stress in responding to food insecurity, and growing expectations to fulfill public roles in disease response measures. However, we also find that the return of male migrants and youth has, in some cases, reduced women's farming responsibilities and created opportunities for household togetherness at a time of great uncertainty. We conclude that more research is needed to examine the nuanced aspects of COVID-19's gendered labor impacts to create comprehensive policy responses to address the multiple and sometimes conflicting effects the lockdown has had on agrarian women's informal labor and well-being.
Cosmopolitan constitutionalism: The case of the European Convention
Authors: SOMEK ALEXANDER
Published: July 2020

Owing to the vagaries of the ‘constitutionalization’ of the European Union, legal scholarship has disregarded the momentous constitutional transformation brought about by the European Convention System. This is regrettable, not least because the Convention has reconfigured national constitutional authority in a cosmopolitan context. The emerging cosmopolitan constitutionalism is based upon three ideas: first, the exercise of state authority must also be legitimate from the perspective of those who are not citizens; second, a constitution must embrace fundamental rights and the representation of insiders in order to facilitate the representation of all, including outsiders; third, the authority of the constitution doesn’t just depend on endorsement by an independent people but also on recognition by other peoples who pursue the same type of political project. At the same time, any cosmopolitan constitutional system needs to leave space for particularity. It is therefore not accidental that the idea of a ‘margin of appreciation’ is of pivotal significance.
PAD screening: why? whom? when? how? – a systematic review
Authors: Kieback Arne G. , Gähwiler Roman , Thalhammer Christoph
Published: July 2020

Summary: An estimated 237 million people suffer from peripheral arterial disease (PAD), which is associated with high morbidity and mortality, and prevalence is still increasing. Currently, we do not have any randomized trials that compare screening to no screening specifically for PAD in the general population. Presently, PAD screening is not generally established. This systematic review gives an overview of relevant literature and guidelines. Screening usually focuses on ankle-brachial index (ABI)-measurement, which enables detection of asymptomatic and symptomatic PAD, but has limitations in diabetics. There are no sufficient data on PAD screening. Guideline recommendations are heterogeneous. While some advocate no screening until better data are available, most recommend selective screening despite insufficient data on morbidity and mortality reduction in consequence of screening. We support the only evidence-based screening strategy for PAD: combined screening for abdominal aortic aneurysm (AAA), PAD and arterial hypertension in men aged 65–74 according to the VIVA study. We additionally suggest a new simple three-step screening strategy for symptomatic PAD in all individuals aged 40 and older, who see a general practitioner: Asking one question (“Do you have pain or cramps in the legs during normal walking?”) followed by physical examination (normal lower extremity pulse status?) in those, whose answer is “yes”, and ABI measurement unless all pulses are normal.
Spatial and Temporal Variations of Arctic Sea Ice From 2002 to 2017
Authors: Wang Zongliang , Li Zhen , Zeng Jiangyuan , Liang Shuang , Zhang Ping , Tang Fuquan , Chen Siyuan , Ma Xiongwei
Published: July 2020

The variation of polar sea ice is an indicator of polar environmental change, which plays an important role in the study of regional and global climate change. In this paper, the latest sea ice data sets from the European Space Agency Climate Change Initiative were firstly combined to comprehensively analyze the spatial and temporal variation of Arctic sea ice concentration (SIC) and sea ice thickness (SIT) from 2002 to 2017. The results show that during this period, the SIC of the Kara Sea and the Barents Sea decreases the most significantly, reaching −1.11%·year−1. The Arctic annual average sea ice extent (SIE) and sea ice area (SIA) exhibit noticeable decreasing trends, reaching −0.0592 × 106 km·year−1 and −0.0628 × 106 km·year−1, respectively. Both of Arctic SIE and SIA vary seasonally, and they reach the minimum values of 4.97 × 106 km2 and 3.96 × 106 km2 in September and the maximum values of 14.58 × 106 km2 and 13.35 × 106 km2 in March, respectively. Moreover, the Arctic SIE and SIA anomaly series from 2002 to 2017 were analyzed based on the linear regression method. It is found the most noticeable decreasing trends of the Arctic SIE and SIA are from July to October. The maximum variation of the SIE is −1.06 × 106 km2(10a)−1, and the maximum variation of the SIA is −1.09 × 106 km2(10a)−1. The Arctic SIE and SIA present the smallest decreasing trends from April to May, which are −0.19 × 106 km2(10a)−1 and −0.2 × 106 km2(10a)−1, respectively. The Arctic SIT also displays a pronounced decreasing trend with −0.015 m·year−1 in autumn and −0.018 m·year−1 in winter. The annual average SIT reaches a minimum of 1.28 m in 2013 and a maximum of 1.66 m in 2005. Particularly, the SIT of the Hudson Bay decreases the most significantly, reaching −0.051 m·year−1. Finally, the Arctic average SIT was tested by the Mann‐Kendall method. It is found that the SIT has a sudden change in 2007, from a slight increase in 2003–2007 to a significant decrease in 2007–2017. Overall, the decreasing trend of the Arctic sea ice (both SIC and SIT) is significant in the past decade. These findings can contribute to future research on polar regions and global climate change.
How Accurately Can Satellite Products (TMPA and IMERG) Detect Precipitation Patterns, Extremities, and Drought Across the Nepalese Himalaya?
Authors: Sharma Shankar , Khadka Nitesh , Hamal Kalpana , Shrestha Dibas , Talchabhadel Rocky , Chen Yingying
Published: July 2020

This study aims to assess the accuracy of two satellite‐based precipitation products (SBPPs), that is, Tropical Rainfall Measurement Mission (TRMM)‐based Multi‐satellite Precipitation Analysis (TMPA) and its upgraded version Integrated Multi‐Satellite Retrievals for Global Precipitation Measurement (IMERG), in capturing spatial and temporal variation of precipitation and their application for extreme events (high‐intensity precipitation and drought). They were evaluated against 142‐gauge stations from Nepal during 2001–2018. The results show that, in general, both SBPPs show the overall characteristics of precipitation patterns, although underestimated the mean annual precipitation during the study period. It was also noted that IMERG product yields better performance to detect precipitation events (probability of detection) and no‐precipitation events (false alarm ratio) than TMPA. Based on four different extreme precipitation indices: heavy precipitation events (R10mm), extreme precipitation events (R25mm), five consecutive dry days (CDD), and five consecutive wet days (CWD), it was observed that the SBPPs underestimated the frequency of R25mm and CDD spells while overestimated R10mm and CWD spells. Additionally, both SBPPs exhibited considerable capabilities in capturing the drought events during the study period. Overall, the drought event, bias, and frequency show that the IMERG product has slightly better capabilities to capture drought than the TMPA product. In general, IMERG was found to be superior at a daily timescale, while TMPA shows consistent performance on a monthly scale during the study period. Furthermore, there is still space for further improvement of IMERG rainfall retrieval algorithms.
Earth Observations Informing Cities’ Operations and Planning
Authors: Hurwitz Margaret , Braneon Christian , Kirschbaum Dalia , Mandarino Felipe , Mansour Raed
Published: July 2020

Rio de Janeiro, Brazil, and Chicago, Ill., are using NASA Earth observations to map, monitor, and forecast water and air quality, urban heat island effects, landslide risks, and more.
Interaction of the Indian and Asian Plates Under the Pamir and Hindu‐Kush Regions: Insights From 3‐D Shear Wave Velocity and Anisotropic Structures
Authors: Liang Yanling , Li Lun , Liao Jie , Gao Rui
Published: July 2020

The Pamir‐Hindu‐Kush region is widely cited as a best place to study opposing continental subduction on Earth. Yet, subducting slab morphology of the Indian and Asian plates under this region remains elusive. Here we report new shear wave velocity and radial anisotropy models from Rayleigh and Love wave tomography to constrain the geometry of these two slabs. Together with previous tomographic studies, we show that the Indian slab exhibits along‐strike variation with subhorizontally underthrusting into the Pamir and high‐angle subduction under the Hindu‐Kush. We speculate that the Indian slab was probably detached and sank into the mantle transition zone under the Pamir, while break‐off process is ongoing under the Hindu‐Kush. The Asian lithospheric mantle and lower crust are inferred to be subducting southward into the North Pamir. Two opposing subducting slabs could have interacted under the Pamir, resulting in thickening crust, horizontally stretched midcrustal flow, and horizontal mantle flow. These dynamic processes could explain surface geologic observations and potentially constrain the causes of intermediate‐depth seismicity.
Evidence for Synchronization in the Global Earthquake Catalog
Authors: Bendick R. , Mencin D.
Published: July 2020

Phase alignment (synchronization) is a generalized property of interacting oscillators. If such interactions apply to earthquakes, they should manifest as time‐dependent variations in earthquake productivity organized according to a characteristic elastic loading period. Defining this period as renewal interval, the time required to accumulate the elastic potential energy released in a rupture, gives a consistent scaling property that can be used to search for temporal organization. We test for the expected structure in earthquake productivity using three different statistical tools optimized for different temporal sensitivities: Schuster spectra for events with short renewal intervals (0–25 years), Fourier power spectra for events with short and intermediate renewal intervals (0–100 years), and topological data analysis (TDA) for events with long renewal intervals (>100 years). All three indicate that earthquakes are organized in time according to renewal interval. Accounting for such unsteady temporal organization may improve forecasting skill by providing time‐dependent event probabilities.
Observed Evidence for Steep Rise in the Extreme Flow of Western Himalayan Rivers
Authors: Chug Divyansh , Pathak Amey , Indu J. , Jain Sharad K. , Jain Sanjay K. , Dimri A. P. , Niyogi Dev , Ghosh Subimal
Published: July 2020

We present the first observational evidence of changing patterns of extreme streamflows at multiple locations across Western Himalayan (WH) rivers. We find that the frequency of extreme flow events during the period 1980–2003 has doubled with a statistically significant increasing trend in annual maximum streamflow. We postulate that this streamflow change is due to the increased precipitation extremes occurring during both the summer monsoon and the winter seasons. We further found a stepwise increase of “chi‐gradient” in Bhagirathi and Sutlej Rivers, indicative of a landscape that facilitates rapid flow of water generating severe floods downstream. Our results highlight the severity of hydroclimatic changes underway in the WH region and the critical need for a hydro‐infrastructure for flood forecasting to benefit more than 17 million inhabitants and for ecosystem services to mitigate increasing flood hazards.
Where Are White Roofs More Effective in Cooling the Surface?
Authors: Wang Linying , Huang Maoyi , Li Dan
Published: July 2020

By reflecting more sunlight, white (cool) roofs experience lower surface temperatures and produce less heating of the surrounding air. The effectiveness of cool roofs, quantified by the surface temperature difference between cool and regular roofs (ΔTs), is known to vary spatially. A common perception is that ΔTs is controlled by solar radiation that reaches the roof surface. Here we use an Earth System Model and a surface energy balance model to show that the spatial variability of ΔTs, when normalized by the albedo difference between cool and regular roofs Δα, is also controlled by an energy distribution factor that encodes the efficiencies of surface energy balance components in dissipating heat. Our results suggest that painting the roof white is more effective when the roof has less water‐holding capacity and smaller thermal admittance and is located in places with more solar radiation, less precipitation, and lower wind speed.
Observation of a New Long‐Period (16‐s) Persistent Tremor Originating in the Gulf of Guinea
Authors: Xia Yingjie , Chen Xiaofei
Published: July 2020

A new persistent microseismic tremor, with a narrowband period centered near 16 s, was discovered in the primary microseism spectral peak by analyzing seismic waveforms recorded by African, European, and American seismometers. This tremor may generate coherent arrivals in noise cross‐correlation functions (NCFs), which could potentially bias ambient noise tomography. Using an envelope‐stacking method, we discovered that the 16‐s tremor source is in the coastal region of the Gulf of Guinea and is probably isolated from the previously reported 26‐s tremor source. The nature of the newly identified 16‐s tremor, like the 26‐ and 27‐s tremors, is similar to a volcanic tremor radiated by the Mayotte volcanic system, thereby suggesting that the excitation of all the Gulf of Guinea tremors may be related to volcanic activities. Thus, this study implies that there may still be active volcanoes in the gulf.
Overpressured Underthrust Sediment in the Nankai Trough Forearc Inferred From Transdimensional Inversion of High‐Frequency Teleseismic Waveforms
Authors: Akuhara Takeshi , Tsuji Takeshi , Tonegawa Takashi
Published: July 2020

Active‐source seismic surveys have resolved the fine‐scale P‐wave velocity (Vp) of the subsurface structure in subduction forearcs. In contrast, the S‐wave velocity (Vs) structure is poorly resolved despite its usefulness in understanding rock properties. This study estimates Vp and Vs structures of the Nankai Trough forearc, by applying transdimensional inversion to high‐frequency teleseismic waveforms. As a result, a thin (∼1 km) low‐velocity zone (LVZ) is evident at ∼6 km depth beneath the sea level, which is located ~3 km seaward from the outer ridge. Based on its high Vp/Vs ratio (∼2.5) and comparison to an existing seismic reflection profile, we conclude that this LVZ reflects a high pore pressure zone at the upper portion of the underthrust sediment. We infer that this overpressured underthrust sediment hosts slow earthquake activities and that accompanied strain release helps impede coseismic rupture propagation further updip.
Simulation of Deep Cycle Turbulence by a Global Ocean General Circulation Model
Authors: Pei Suyang , Shinoda Toshiaki , Wang Wanqiu , Lien Ren‐Chieh
Published: July 2020

Deep cycle turbulence (DCT) is a diurnally oscillating turbulence that penetrates into a stratified shear layer below the surface mixed layer, which is often observed in the eastern Pacific and Atlantic above the Equatorial Undercurrent (EUC). Here we present the simulation of DCT by a global ocean general circulation model (OGCM) for the first time. As the k‐ε vertical mixing scheme is used in the OGCM, the simulation of observed DCT structure based on in situ microstructure measurements can be explicitly demonstrated. The simulated DCT is found in all equatorial ocean basins, and its characteristics agree very well with observations. Zonal and meridional variations of DCT in the entire equatorial Pacific and Atlantic are described through constructing the composite diurnal cycle. In the central Pacific where the maximum shear associated with EUC is deep, the separation of DCT from the surface mixed layer is much more prominent than other areas.
Nearshore Zone Dynamics Determine Pathway of Organic Carbon From Eroding Permafrost Coasts
Authors: Jong Dirk , Bröder Lisa , Tanski George , Fritz Michael , Lantuit Hugues , Tesi Tommaso , Haghipour Negar , Eglinton Timothy I. , Vonk Jorien E.
Published: July 2020

Collapse of permafrost coasts delivers large quantities of particulate organic carbon (POC) to Arctic coastal areas. With rapidly changing environmental conditions, sediment and organic carbon (OC) mobilization and transport pathways are also changing. Here, we assess the sources and sinks of POC in the highly dynamic nearshore zone of Herschel Island‐Qikiqtaruk (Yukon, Canada). Our results show that POC concentrations sharply decrease, from 15.9 to 0.3 mg L−1, within the first 100–300 m offshore. Simultaneously, radiocarbon ages of POC drop from 16,400 to 3,600 14C years, indicating rapid settling of old permafrost POC to underlying sediments. This suggests that permafrost OC is, apart from a very narrow resuspension zone (<5 m water depth), predominantly deposited in nearshore sediments. While long‐term storage of permafrost OC in marine sediments potentially limits biodegradation and its subsequent release as greenhouse gas, resuspension of fine‐grained, OC‐rich sediments in the nearshore zone potentially enhances OC turnover.
On Representative Elementary Volumes of Grayscale Micro‐CT Images of Porous Media
Authors: Singh Ankita , Regenauer‐Lieb Klaus , Walsh Stuart D. C. , Armstrong Ryan T. , van Griethuysen Joost J. M. , Mostaghimi Peyman
Published: July 2020

The concept of linking pore‐scale data to continuum‐scale characteristics of porous media relies on the existence of a representative elementary volume (REV). The current techniques for estimating REVs require access to segmented micro‐computed tomographic (micro‐CT) images and computations of petrophysical properties which are computationally intensive and time‐consuming. Herein, a texture characterization method called the Gray‐Level Size Zone Matrix (GLSZM) is applied directly to raw grayscale micro‐CT images. GLSZM representations of 3D micro‐CT images capture information regarding the connectivity of gray‐level intensities, termed as “size‐zones.” Statistical descriptors of pore space are calculated based on GLSZM to understand the connectivity of low gray‐level intensities. These GLSZM statistics capture microstructural fluctuations and offer insights into the impact of grayscale heterogeneity on REV size. This approach allows REV sizes to be estimated directly using grayscale micro‐CT images, in a reproducible, less time‐consuming and computationally efficient manner.
Direct Observation of Shock‐Induced Disordering of Enstatite Below the Melting Temperature
Authors: Hernandez J.‐A. , Morard G. , Guarguaglini M. , Alonso‐Mori R. , Benuzzi‐Mounaix A. , Bolis R. , Fiquet G. , Galtier E. , Gleason A. E. , Glenzer S. , Guyot F. , Ko B. , Lee H. J. , Mao W. L. , Nagler B. , Ozaki N. , Schuster A. K. , Shim S. H. , Vinci T. , Ravasio A.
Published: July 2020

We report in situ structural measurements of shock‐compressed single crystal orthoenstatite up to 337 ± 55 GPa on the Hugoniot, obtained by coupling ultrafast X‐ray diffraction to laser‐driven shock compression. Shock compression induces a disordering of the crystalline structure evidenced by the appearance of a diffuse X‐ray diffraction signal at nanosecond timescales at 80 ± 13 GPa on the Hugoniot, well below the equilibrium melting pressure (>170 GPa). The formation of bridgmanite and post‐perovskite have been indirectly reported in microsecond‐scale plate‐impact experiments. Therefore, we interpret the high‐pressure disordered state we observed at nanosecond scale as an intermediate structure from which bridgmanite and post‐perovskite crystallize at longer timescales. This evidence of a disordered structure of MgSiO3 on the Hugoniot indicates that the degree of polymerization of silicates is a key parameter to constrain the actual thermodynamics of shocks in natural environments.
A Dynamical Framework for Interpreting Ancient Sea Surface Temperatures
Authors: Judd Emily J. , Bhattacharya Tripti , Ivany Linda C.
Published: July 2020

Efforts to estimate past global mean temperature and latitudinal gradients must contend with spatial heterogeneity in sea surface temperatures (SSTs). Here, we use modern SSTs to show that the environments from which most paleoclimatic data are drawn, shallow epeiric seas and continental margins, are systematically offset from zonal mean temperatures. Epeiric seas are warmer and more seasonal than open‐ocean values from the same latitudes, while continental margins exhibit consistent and predictable deviations related to gyre circulation. Warm temperatures inferred from Paleozoic proxy data may largely reflect that these data derive almost entirely from epeiric seas. Moreover, pseudoproxy analysis using Paleogene sampling localities demonstrates how undersampling of the full range of dynamical environments associated with gyre circulation can generate spurious estimates of latitudinal temperature gradients. Recognition of these global patterns permits a predictive framework within which to more robustly interpret proxy data, improve Earth system models, and reconstruct ancient dynamic regimes.
Record‐Low Arctic Stratospheric Ozone in 2020: MLS Observations of Chemical Processes and Comparisons With Previous Extreme Winters
Authors: Manney Gloria L. , Livesey Nathaniel J. , Santee Michelle L. , Froidevaux Lucien , Lambert Alyn , Lawrence Zachary D. , Millán Luis F. , Neu Jessica L. , Read William G. , Schwartz Michael J. , Fuller Ryan A.
Published: July 2020

Aura Microwave Limb Sounder (MLS) measurements show that chemical processing was critical to the observed record‐low Arctic stratospheric ozone in spring 2020. The 16‐year MLS record indicates more polar denitrification and dehydration in 2019/2020 than in any Arctic winter except 2015/2016. Chlorine activation and ozone depletion began earlier than in any previously observed winter, with evidence of chemical ozone loss starting in November. Active chlorine then persisted as late into spring as it did in 2011. Empirical estimates suggest maximum chemical ozone losses near 2.8 ppmv by late March in both 2011 and 2020. However, peak chlorine activation, and thus peak ozone loss, occurred at lower altitudes in 2020 than in 2011, leading to the lowest Arctic ozone values ever observed at potential temperature levels from ∼400–480 K, with similar ozone values to those in 2011 at higher levels.