bluuebunny/crossref_metadata_2025 huggingface dataset:
Humeanism in light of quantum gravity
Authors: Cinti Enrico , Sanchioni Marco
Published: July 2021

Quantum Theory and Humeanism have long been thought to be incompatible due to the irreducibility of the correlations involved in entangled states. In this paper, we reconstruct the tension between Humeanism and entanglement via the concept of causal structure, and provide a philosophical introduction to the ER=EPR conjecture. With these tools, we then show how the concept of causal structure and the ER=EPR conjecture allow us to resolve the conflict between Humeanism and entanglement.
Eco-friendly highly efficient BN/rGO/TiO2 nanocomposite visible-light photocatalyst for phenol mineralization
Authors: Al-Kandari Shekhah , Abdullah Aboubakr M. , Al-Kandari Halema , Nasrallah Gheyath K. , Sharaf Mohammed A. , AlMarzouq Douaa S. , Mohamed Ahmed M. , Younes Nadin , Kafour Nada , Al-Tahtamouni Talal
Published: July 2021

Boron nitride (BN) and reduced graphene oxide (rGO) of different loadings were composited with commercial P25 TiO2 (Ti) through the hydrothermal method. The as-prepared nanocomposites were characterized using various techniques: X-ray photoelectron spectroscopy, X-ray diffraction, thermal gravimetric analysis, Fourier transform infrared and Raman spectroscopies, and transmission and scanning electron microscopies. It was observed that 10% and 0.1% of BN and rGO, respectively, loaded on TiO2 (10BNr0.1GOTi) resulted in the best nanocomposite in terms of phenol degradation under simulated sunlight. A 93.4% degradation of phenol was obtained within 30 min in the presence of H2O2. Finally, to ensure the safe use of BNrGOTi nanoparticles in the aquatic environment, acute zebrafish toxicity (acutoxicity) assays were studied. The 96-h acute toxicity assays using the zebrafish embryo model revealed that the LC50 for the BNrGOTi nanoparticle was 677.8 mg L−1 and the no observed effect concentration (NOEC) was 150 mg L−1. Therefore, based on the LC50 value and according to the Fish and Wildlife Service Acute Toxicity Rating Scale, BNrGOTi is categorized as a “practically not toxic” photocatalyst for water treatment.
Grip strength performance from 9431 participants of the GenoFit study: normative data and associated factors
Authors: Pratt Jedd , De Vito Giuseppe , Narici Marco , Segurado Ricardo , Dolan Jackie , Conroy Judith , Boreham Colin
Published: July 2021

Weak grip strength is a strong predictor of multiple adverse health outcomes and an integral diagnostic component of sarcopenia. However, the limited availability of normative data for certain populations impedes the interpretation of grip performance across adulthood. This study aimed to establish normative data and low grip strength thresholds in a large adult population, and to examine associations between grip strength and clinically relevant health variables. A total of 9431 adults aged between 18 and 92 years participated in this study (mean age: 44.8 ± 13.4 years; 57% females). Grip strength, body composition, and cardiorespiratory (CR) fitness were assessed using hand dynamometry, dual-energy x-ray absorptiometry and physical work capacity tests, respectively. Low grip strength was established according to criteria of the European Working Group on Sarcopenia in Older People. Normative data and t-scores, stratified by sex and age groups, are presented. Grip performance was associated with lean mass, skeletal muscle index (SMI), fat mass, CR fitness, bone mineral density (BMD), android/gynoid ratio, disease prevalence and physical activity levels (all p < 0.001) after controlling for multiple potential confounders. Individuals with weak grip strength had lower lean mass, SMI, CR fitness (all p < 0.001) and BMD (p = 0.001), and higher disease prevalence (p < 0.001), compared to healthy controls, although sex-specific differences were observed. Grip strength has practical screening utility across a range of health domains. The normative data and grip strength thresholds established in this study can guide the clinical interpretation of grip performance and facilitate timely therapeutic strategies targeting sarcopenia.
Above and beyond meat: the role of consumers’ dietary behavior for the purchase of plant-based food substitutes
Authors: Kopplin Cristopher Siegfried , Rausch Theresa Maria
Published: July 2021

Shrinking meat intake levels and simultaneously increasing consumption of plant-based products among consumers suggest that consumers’ dietary behavior implies the purchase of plant-based food substitutes. We contribute to the literature by investigating the most important determinants of consumers’ dietary behavior and attitude towards plant-based food substitutes and whether consumers’ dietary behavior is of relevance for the attitude towards plant-based food substitutes. Data of 1,363 consumers was used for structural equation modeling as well as necessary condition analysis. Consumers’ dietary behavior is found to play only a minor role in attitude formation towards plant-based food substitutes. Dietary behavior is primarily influenced by animal welfare concerns. We did not find environmental concerns, consumers’ perceived effectiveness, and health consciousness to influence dietary behavior. However, as consumers associate a high standard of animal welfare with healthiness and food safety, following a plant-based diet due to animal welfare concerns might be an altruistic pretext for health consciousness as an egoistic motive.
When do service suppliers leave their platform?—The role of friendships
Authors: Rossmannek Oliver
Published: July 2021

Platform organizations connect suppliers with customers. A key success factor for these organizations is the maintenance of a stable base of loyal suppliers. Interpersonal relationships (i.e., friendships) seem to be an ideal measure of suppliers’ loyalty, as the literature generally indicates that friendships within organizations decrease turnover intention. However, platforms are not fully comparable to traditional organizations, and the correlation between friendships and suppliers’ turnover intention is more complicated for platforms. To demonstrate that, this study analyzed a unique dataset from the music industry. The sample included 101 techno DJs (i.e., service suppliers) from 61 booking agencies (i.e., service platforms). The findings show that service suppliers’ turnover intention is considerably lower when they maintain friendships with the platform’s employees. However, friendships with other suppliers who use the same platform do not affect turnover intention. Managers of service platforms could use the results and suggestions of this paper to adapt their management practices to better suit their service suppliers.
Anatomical Joint Form Variation in Sacroiliac Joint Disease: Current Concepts and New Perspectives
Authors: Ziegeler Katharina , Hermann Kay Geert A. , Diekhoff Torsten
Published: July 2021

Purpose of Review

The aim of this article is to further the understanding of anatomical variation of the sacroiliac joint (SIJ) within the rheumatological community and point out promising fields of research in the interplay of SIJ anatomy and joint disease.

Recent Findings

Mechanical strain has long been implicated in onset and progression of axial spondyloarthritis (axSpA). Recent investigations found changes in the pattern of degenerative lesions of the SIJ in the normal population in patients with atypical joint forms. Furthermore, atypical SIJ forms are more prevalent in patients with axial spondyloarthritis and mechanical SIJ disease.

Mechanical stress from anatomical joint form variation may have an impact on development and progression of axSpA. Furthermore, mechanically induced bone marrow edema may act as an axSpA mimic on MRI and needs to be more accurately classified.
Work on the cutting edge: metallographic investigation of Late Bronze Age tools in southeastern Lower Austria
Authors: Mödlinger Marianne , Trebsche Peter
Published: July 2021

This paper analyses 20 Late Bronze Age (ca 1080–800 BC) copper alloy objects to discern their manufacture and the skills of local craftsmen. Several tools and jewellery were studied that originated from a bronze workshop located immediately next to the Prigglitz-Gasteil copper ore mining site and several contemporaneous sites in the surrounding area. The samples were studied with optical microscopy (microstructurally), and SEM-EDXS and XRF (chemical analyses). Our analyses are part of a larger study and suggest that the Prigglitz region’s bronze production was not standardized. Particular alloys do not seem to have been chosen for object types or due to their intended use-function. Notably, approximately 20% of the objects contain unalloyed copper inclusions, which are most likely a result of the incomplete mixing of scrap metals and alloys during their production.
Nutrigenetic comparison of two Varroa-resistant honey bee stocks fed pollen and spirulina microalgae
Authors: Ricigliano Vincent A , Ihle Kate E , Williams Steven T
Published: July 2021

We tested the influence of genetic variation on responses to natural and artificial diets in Varroa-resistant Pol-line and Russian honey bee stocks. Newly emerged workers from six colonies per stock were fed pollen, spirulina (blue-green microalgae), and sucrose-only diets in 144 total cages. Diet type had a strong effect on sugar intake, body weight, fat body lipid content, and vitellogenin (vg) expression. Spirulina consumption was approximately half that of pollen, but led to higher head weights, equivalent thorax weights and vg levels, and marginally reduced fat body lipids. Bee stock and colony had a significant impact on nutritional response. Despite equivalent diet intakes, Pol-line bees accumulated higher lipid levels and consumed less sugar overall than Russian bees. Furthermore, pollen-fed bees sourced from Pol-line colonies had significantly higher vg levels. These differences in nutrient and energy allocation may reflect life history-related physiological tradeoffs. Our results suggest that genotype-dependent nutritional responses are present in honey bees, with promising implications for breeding efforts and tailored approaches to diet and health in a changing global climate.
Clinical features of gastroenteritis during a large waterborne Campylobacter outbreak in Askøy, Norway
Authors: Emberland Knut Erik , Wensaas K.-A. , Litleskare S. , Iversen A. , Hanevik K. , Langeland N. , Rortveit G.
Published: July 2021

Purpose

Outbreaks of Campylobacter infection are common, but studies exploring the clinical features of acute illness in the outbreak setting are scarce in existing literature. The main purpose of the present study was to investigate the clinical features of self-reported acute illness in gastroenteritis cases during a large waterborne Campylobacter outbreak in Askøy municipality, Norway, in 2019.

Methods

A web-based self-administered questionnaire, and invitation to participate was sent by the municipality of Askøy as text message to mobile phones using the municipality’s warning system to the inhabitants during the ongoing outbreak.

Results

Out of 3624 participants, 749 (20.7%) were defined as cases, of which 177 (23.6%) reported severe gastroenteritis. The most common symptoms were loose stools (90.7%), abdominal pain (89.3%) and diarrhea (88.9%), whereas 63.8% reported fever, 50.2% joint pain and 14.2% bloody stools. Tiredness, a symptom non-specific to gastroenteritis, was the overall most common symptom (91.2%).

Conclusion

About one in four of the cases reported symptoms consistent with severe gastroenteritis. We found more joint pain and less bloody stools than reported in published studies of laboratory confirmed campylobacteriosis cases. Tiredness was common in the current study, although rarely described in previous literature of acute illness in the outbreak setting.
A safe and easy-to-use ultrasound-guided hydrodissection technique for the carpal tunnel syndrome: a minimally invasive approach
Authors: Mathieu Thomas , Lemmens Els , Stassijns Gaëtane
Published: July 2021

Carpal tunnel syndrome (CTS), compression of the median nerve lying deep under the flexor retinaculum, is the most common entrapment neuropathy of the upper limb. After a failure of conservative treatments, such as non-steroidal anti-inflammatory drugs (NSAIDs) and splinting, interventional techniques are required. Hydrodissection is an injection technique that separates the nerve from the surrounding tissue. Although this technique is gaining ground in modern medicine, the state-of-the-art literature is lacking a clear protocol or approach for hydrodissection for CTS. In this article, we describe a safe, minimally invasive, effective, and easy-to-use ultrasound-guided hydrodissection technique for CTS.
“Even the NGOs Never Talk About Ufiti [Witchcraft]”: a Decolonial and Feminist Cultural Psychological Analysis of Individualized Development Clashing with Communal Ways of Being
Authors: Adolfsson Johanna Sofia , Moss Sigrun Marie
Published: July 2021

Conducting a multi-sited psychology study on how Malawian participants perceive Western-oriented non-governmental organizations’ (NGOs) gendered development approaches, it became apparent that perceptions of ufiti (the Malawian term for what loosely translates as witchcraft in English)—and its gendered inclination—was highly relevant. As in many parts of the world, people in Malawi may relate themselves and their social world in connection to spiritual and supernatural dimensions, manifested in practices and discourses often closely linked to communal norms and values. Many international NGOs in Malawi run individualized development initiatives, often particularly focusing on women and girls’ personal empowerment. When local communal ways of experiencing and knowing are not taken account for in the NGOs’ interventions, this indiviualized approach can spur interpersonal resentment, and in worst-case ufiti assaults. This article explores the link between individualized development incentives and perceptions of ufiti. Using decolonial and feminist cultural psychology as a lens, we ask how the individualized focus of the NGOs plays out in Malawi, and what negative and unintended consequences individualized interventions can lead to. Our results indicate the need for contextually grounded and informed development approaches, to avoid that effort to empower individual women and girls lead to their disempowerment, social disruption, and ufiti accusations and assaults. The article speaks to the need for decolonial and feminist cultural psychological approaches that consider subjective intentional worlds.
Temperature dependence of nanosecond charge recombination in mutant Rhodobacter sphaeroides reaction centers: modelling of the protein dynamics
Authors: Gibasiewicz Krzysztof , Pajzderska Maria , Białek Rafał , Jones Michael R.
Published: July 2021

We investigated the influence of a range of factors—temperature, redox midpoint potential of an electron carrier, and protein dynamics—on nanosecond electron transfer within a protein. The model reaction was back electron transfer from a bacteriopheophytin anion, HA−, to an oxidized primary electron donor, P+, in a wild type Rhodobacter sphaeroides reaction center (RC) with a permanently reduced secondary electron acceptor (quinone, QA−). Also used were two modified RCs with single amino acid mutations near the monomeric bacteriochlorophyll, BA, located between P and HA. Both mutant RCs showed significant slowing down of this back electron transfer reaction with decreasing temperature, similar to that observed with the wild type RC, but contrasting with a number of single point mutant RCs studied previously. The observed similarities and differences are explained in the framework of a (P+BA− ↔ P+HA−) equilibrium model with an important role played by protein relaxation. The major cause of the observed temperature dependence, both in the wild type RC and in the mutant proteins, is a limitation in access to the thermally activated pathway of charge recombination via the state P+BA− at low temperatures. The data indicate that in all RCs both charge recombination pathways, the thermally activated one and a direct one without involvement of the P+BA− state, are controlled by the protein dynamics. It is concluded that the modifications of the protein environment affect the overall back electron transfer kinetics primarily by changing the redox potential of BA and not by changing the protein relaxation dynamics.
Escalated dose donor lymphocyte infusion treatment in patients with primary immune deficiencies after HSCT with reduced-intensity conditioning regimen
Authors: Ali Tahani , Behfar Maryam , Mohseni Rashin , Salajegheh Pourya , Kheder Maged , Abou-Fakher Faihaa , Nikfetrat Zeynab , Jafari Fahimeh , Naji Parisa , Hamidieh Amir Ali
Published: July 2021

Objective/Background:

Mixed chimerism is a major concern after allogenic hematopoietic stem cell transplantation (HSCT) using a reduced-intensity conditioning (RIC) regimen in primary immunodeficiencies (PIDs). A donor lymphocyte infusion (DLI) escalating dose regimen has been developed with the aim of reducing toxicity while preserving efficacy. However, the graft-versus-host disease (GvHD) development remains the most common and adverse effect of DLI and continues to be a limiting factor in its application, especially nonmalignant diseases such as PIDs. We prospectively evaluated PID patients after HSCT using RIC in Children s Medical Center, who were candidates for an escalating dose of DLI for MC from 2016 to 2018.

Methods:

With the median follow-up of 16.4 months, 12 patients (nine males and three females) with a median age of 3.72 years received DLI. The median number of DLI was 3.2 (range, 1–5), the maximum and total dose of DLIs administered per patient were 3.6 × 107 (range, 1–5) cells/kg CD3+ and 9.3 × 107 (range, 1–15) cells/kg CD3+ cells, respectively.

Results:

Median donor chimerism at baseline before the DLIs was 41% (range, 11–73%), patients received DLIs at a median of 105 (range, 37–230) days and 52 (range, 3–168) days after the HSCT and onset of the MC, respectively. At the final assessment, six (54.5%) patients improved after DLIs at a median of 47.3 days.

Conclusion:

PID patients may benefit from DLI with an escalating dose regimen, but the GvHD development remains a concern during the DLI, and the optimum dose and frequency must be standardized.
African Studies Keyword: Democracy
Authors: Cheeseman Nic , Sishuwa Sishuwa
Published: July 2021

Democracy is one of the most contested words in the English language. In Africa, these complexities are compounded by the question of whether democracy is a colonial imposition. Cheeseman and Sishuwa provide a historiography of debates around democracy, track how these narratives have developed over time, and argue that there is widespread public support for a form of what they call “consensual democracy.” This is not to say that democracy is universally loved, but despite the controversy it remains one of the most compelling ideals in political life, even in countries in which it is has yet to be realized.
Nostalgia of a Frustrated Ottoman Subject: Reading Osman Agha of Timișoara's Memoirs as Self-Narrative
Authors: Aksoy Sheridan R. Aslıhan
Published: July 2021

Ego-documents let us hear the voices of those who have been little heard in historiography. Such documents, especially when narrative in nature, provide insight into historical events and periods by illustrating how individuals—in correspondence with their own (in)actions, (in)decisions, and (mis)convictions as well as emotions, fears, aspirations, and frustrations—experienced and perceived these historical phenomena from a contemporary personal viewpoint. Since the revival of narrative historiography in the 1980s, partly in response to the Annales school, such documents have been increasingly recognized and employed as important historical sources. Nonetheless, the terminology for designating the generic nature and encompassing the diversity of such sources, as well as the methodology for historicizing them, remain under debate.
Vertical and Horizontal Agency Problems in Private Firms: Ownership Structure and Operating Performance
Authors: Gogineni Sridhar , Linn Scott C. , Yadav Pradeep K.
Published: July 2021

We investigate how ownership structure influences operating performance and implied agency costs. Our sample includes over 42,000 U.K. private and public firms. We document several new results of considerable economic significance relating to i) horizontal agency costs arising from unequal ownership within private firms, ii) amplification of agency costs from joint presence within the same firm of horizontal agency problems and vertical agency problems arising from separation of ownership and control, iii) mitigation in agency costs wrought by a second large shareholder, iv) impact of complex ownership structures, and v) agency cost differences between public firms and comparable private firms.
Phonological contrasts and gradient effects in ongoing lenition in the Spanish of Gran Canaria
Authors: Broś Karolina , Żygis Marzena , Sikorski Adam , Wołłejko Jan
Published: July 2021

This study explores ongoing lenition of postvocalic /p t k b d g/ in the Spanish of Gran Canaria. Duration, intensity and harmonics-to-noise ratio of 16,454 sounds produced by 44 native speakers were measured, with the latter phonetic parameter used for the first time to investigate lenition. The results show a path of gradual sound shortening and opening from voiceless stops to open approximants, as well as systematic use of six different variants depending on the underlying representation and phonological context: two types of [p t k], two types of [b d g] and two types of [β˕ ð˕ ɣ˕]. We interpret this as continuity lenition that leads to the flattening of the intensity contour and harmonicity of the target segment with respect to the flanking sounds. We argue that a phonological analysis of this process that accounts for its non-neutralising character requires the use of a scalar [aperture] feature.
The dynamical landscape: phonological acquisition and the phonology–phonetics link
Authors: Łukaszewicz Beata
Published: July 2021

During acquisition children internalise adult-based phonological patterns and alternately adopt and discard child-specific patterns reflecting their unskilled production. The child-specific patterns are often assumed to be low-level phonetic effects, and so, in a classical modular feedforward grammar, they should not interfere with the higher-level adult-based phonology. This paper reports an interaction in which the application of a categorical adult-based process (Voice Assimilation) is conditioned by a gradient child-specific process (fricative devoicing). Acoustic analyses of longitudinal data from a Polish-speaking child reveal variable Voice Assimilation effects in target voiced fricative–stop/stop–fricative clusters (voicing and devoicing), correlated with the extent of voicing in fricatives in non-assimilatory contexts. I analyse this phonology–phonetics trade-off by appealing to symbol-like dynamical representations, expressed in the language of non-linear mathematics. Such representations offer a non-derivational link between the qualitative and quantitative aspects of speech. Variability ensues as a natural consequence of grammar change.
Prenatal maternal stress during the COVID-19 pandemic and infant regulatory capacity at 3 months: A longitudinal study
Authors: Provenzi Livio , Grumi Serena , Altieri Lilia , Bensi Giulia , Bertazzoli Emanuela , Biasucci Giacomo , Cavallini Anna , Decembrino Lidia , Falcone Rossana , Freddi Anna , Gardella Barbara , Giacchero Roberta , Giorda Roberto , Grossi Elena , Guerini Paola , Magnani Maria Luisa , Martelli Paola , Motta Mario , Nacinovich Renata , Pantaleo Dario , Pisoni Camilla , Prefumo Federico , Riva Laura , Scelsa Barbara , Spartà Maria V. , Spinillo Arsenio , Vergani Patrizia , Orcesi Simona , Borgatti Renato ,   MOM-COPE Study Group
Published: July 2021

The COVID-19 pandemic is a global traumatic experience for citizens, especially during sensitive time windows of heightened plasticity such as pregnancy and neonatal life. Pandemic-related stress experienced by mothers during pregnancy may act as an early risk factor for infants’ regulatory capacity development by altering maternal psychosocial well-being (e.g., increased anxiety, reduced social support) and caregiving environment (e.g., greater parenting stress, impaired mother–infant bonding). The aim of the present longitudinal study was to assess the consequences of pandemic-related prenatal stress on infants’ regulatory capacity. A sample of 163 mother–infant dyads was enrolled at eight maternity units in northern Italy. They provided complete data about prenatal stress, perceived social support, postnatal anxiety symptoms, parenting stress, mother–infant bonding, and infants’ regulatory capacity at 3 months of age. Women who experienced emotional stress and received partial social support during pregnancy reported higher anxious symptoms. Moreover, maternal postnatal anxiety was indirectly linked to the infants’ regulatory capacity at 3 months, mediated by parenting stress and mother–infant bonding. Dedicated preventive interventions should be delivered to mothers and should be focused on protecting the mother–infant dyad from the detrimental effects of pandemic-related stress during the COVID-19 healthcare emergency.
Prevalence of childhood anaemia in Brazil: still a serious health problem: a systematic review and meta-analysis
Authors: Nogueira-de-Almeida Carlos Alberto , Ued Fábio da Veiga , Del Ciampo Luiz Antonio , Martinez Edson Zangiacomi , Ferraz Ivan Savioli , Contini Andrea Aparecida , Cruz Franciele Carolina Soares da , Silva Raquel Farias Barreto , Nogueira-de-Almeida Maria Eduarda , Lamounier Joel Alves
Published: July 2021

Objective:

To estimate the prevalence of anaemia in Brazilian children up to 83·9 months old.

Design:

Systematic review and meta-analysis, using databases PubMed, Scopus, SciELO, Lilacs, Google Scholar, Periódicos Capes, Arca, Biblioteca Virtual em Saúde, Microsoft Academic Search and Cochrane Library using search terms: anaemia, prevalence, child and Brazil. PROSPERO Registration number: CRD42020208818.

Setting:

Cross-sectional, cohort, case–control and intervention studies published between 2007 and 2020 were searched, excluding those who assessed children with an illness or chronic condition. The main outcome was anaemia prevalence. Random effects models based on the inverse variance method were used to estimate pooled prevalence measures. Sensitivity analyses removed studies with high contribution to overall heterogeneity.

Participants:

From 6790 first screened, 134 eligible studies were included, totalling 46 978 children aged zero to 83·9 months analysed, with adequate regions representativeness.

Results:

Pooled prevalence of anaemia was 33 % (95 % CI 30, 35). Sensitivity analyses showed that withdrawal of studies that contributed to high heterogeneity did not influence national average prevalence.

Conclusions:

Childhood anaemia is still a serious public health problem in Brazil, exposing 33 % of Brazilian children to the anaemia repercussions. The main limitation of the study is the estimation of national prevalence based on local surveys, but a large number of studies were included, with representation in all regions of the country, giving strength to the results. In Brazil, more public policies are needed to promote supplementation, fortification and access to healthy eating to reduce the high level of anaemia among children.
A MATHEMATICAL COMMITMENT WITHOUT COMPUTATIONAL STRENGTH
Authors: FREUND ANTON
Published: July 2021

We present a new manifestation of Gödel’s second incompleteness theorem and discuss its foundational significance, in particular with respect to Hilbert’s program. Specifically, we consider a proper extension of Peano arithmetic (
$\mathbf {PA}$
) by a mathematically meaningful axiom scheme that consists of
$\Sigma ^0_2$
-sentences. These sentences assert that each computably enumerable (
$\Sigma ^0_1$
-definable without parameters) property of finite binary trees has a finite basis. Since this fact entails the existence of polynomial time algorithms, it is relevant for computer science. On a technical level, our axiom scheme is a variant of an independence result due to Harvey Friedman. At the same time, the meta-mathematical properties of our axiom scheme distinguish it from most known independence results: Due to its logical complexity, our axiom scheme does not add computational strength. The only known method to establish its independence relies on Gödel’s second incompleteness theorem. In contrast, Gödel’s theorem is not needed for typical examples of
$\Pi ^0_2$
-independence (such as the Paris–Harrington principle), since computational strength provides an extensional invariant on the level of
$\Pi ^0_2$
-sentences.
Close Observation of Hydraulic Fracturing at EGS Collab Experiment 1: Fracture Trajectory, Microseismic Interpretations, and the Role of Natural Fractures
Authors: Fu Pengcheng , Schoenball Martin , Ajo‐Franklin Jonathan B. , Chai Chengping , Maceira Monica , Morris Joseph P. , Wu Hui , Knox Hunter , Schwering Paul C. , White Mark D. , Burghardt Jeffrey A. , Strickland Christopher E. , Johnson Timothy C. , Vermeul Vince R. , Sprinkle Parker , Roberts Benjamin , Ulrich Craig , Guglielmi Yves , Cook Paul J. , Dobson Patrick F. , Wood Todd , Frash Luke P. , Huang Lianjie , Ingraham Mathew D. , Pope Joseph S. , Smith Megan M. , Neupane Ghanashyam , Doe Thomas W. , Roggenthen William M. , Horne Roland , Singh Ankush , Zoback Mark D. , Wang Herb , Condon Kate , Ghassemi Ahmad , Chen Hao , McClure Mark W. , Vandine George , Blankenship Douglas , Kneafsey Timothy J. ,   EGS Collab Team
Published: July 2021

Despite the wide application of hydraulic fracturing in enhanced geothermal system (EGS) development and unconventional hydrocarbon production, our understanding of the many factors affecting the propagation of hydraulic fractures has relied on circumstantial evidence. This is partly due to the scarcity of direct observations in the subsurface. The EGS Collab project attempts to address these issues in the context of EGS research by performing intermediate‐scale (∼10 m) hydraulic stimulation experiments in a thoroughly characterized and heavily instrumented underground testbed. This paper analyzes the data collected from the first suite of hydraulic fracturing tests in this testbed, consisting of seven stimulation episodes. High‐quality microseismic data delineate five planar features very clearly. Combining fracture‐wellbore intersection observations from distributed temperature sensing (DTS) and visual observations from an open‐hole well, as well as prior in‐situ stress measurements, we conclude with high certainty that the four larger planes were hydraulic fractures. The growth of the hydraulic fractures was temporarily halted by a prominent, open natural fracture in the testbed but they eventually crossed and slightly reoriented under continued stimulation. Mineral‐filled (i.e., healed) natural fractures, though prevalent in the testbed, did not have perceivable effects on hydraulic fracture propagation. The high‐quality, mutually corroborating data sets allowed conclusions to be drawn with high confidence and attests to the advantage of intermediate‐scale experiments in subsurface research.
Earthquake Source Mechanisms and Stress Field Variations Associated With Wastewater‐Induced Seismicity in Southern Kansas, USA
Authors: Amemoutou Amandine , Martínez‐Garzón Patricia , Kwiatek Grzegorz , Rubinstein Justin L. , Bohnhoff Marco
Published: July 2021

The strong increase of seismicity rates in the contiguous USA over the last 10 years is linked to the injection of huge amounts of wastewater from oil and gas production in unconventional hydrocarbon reservoirs. We calculated 549 moment tensors of induced earthquakes (MW ≤ 4.9) in southern Kansas to study their source mechanisms and their relation to injection activity. Seventeen percent of the events analyzed contained significant volumetric (ISO%) components, and these events mostly occurred near the two largest local earthquakes during the 4 months of largest active wastewater disposal. Mapping the local stress field, we determined that most of the region lies within a transtensional stress regime, with a maximum horizontal stress σHmax trending N75°E. In the epicentral area of the MW 4.9 Milan earthquake, the σHmax trend is rotated to about S80°E. Locally, two areas display a change in the stress field orientation with depth, from transtensional above 5.5 km depth to strike slip deeper in the basement. Relating the resolved fault geometries to the obtained local stress field orientation, we find that most of the activated fault planes were optimally oriented to the current stress field and thus small stress perturbations caused by the water injection could lead to failure.
Modeling Volcanic Debris Clouds
Authors: Derouin Sarah
Published: July 2021

How does a large volcanic cloud get into the stratosphere? Scientists model how volcanic debris injected into the lower stratosphere can be lofted high into the middle stratosphere.
Long‐Term 15N Balance After Single‐Dose Input of 15N‐Labeled NH4+ and NO3− in a Subtropical Forest Under Reducing N Deposition
Authors: Xie Danni , Duan Lei , Si Gaoyue , Liu Wenjing , Zhang Ting , Mulder Jan
Published: July 2021

Nitrogen (N) deposition in Europe and North America decreased in the 1990s, whereas N deposition in China began to decline in the early 2010s. The response of temperate forests to decreasing N deposition implied a delay recovery, but it remains unknown whether recovery in subtropical forests follows a similar trend. Therefore, the effects of decreased N deposition on N leaching were simulated in an N‐saturated forest in southwest China following ten years of N application 4.00 g N m−2 yr−1. The addition of N (NH4+ or NO3−) was stopped in 2014. In 2017, a single in‐situ 15N addition as NH4+ or NO3− was performed to trace the fate of N under reducing N deposition. Combining the monitoring results of the N fluxes and 15N fates, both the actual N leaching and contribution of a “new” N input to N leaching were significantly reduced in response to decreasing the N input. The termination of N addition resulted in immediate decreases in the N mineralization and immobilization rates, which were even lower than those in the control plots with moderate (naturally occurring) deposition reduction. The ratio of N leaching from mineralization was also reduced, implying the critical role of N mineralization in the recovery from N saturation. Because the forest was still N‐saturated, decreasing N deposition slightly reduced the N leaching to the gross N input ratio (including both N deposition and N mineralization). The significant decrease in the ratio and thus leaching recovery may occur due to a significant N deposition reduction.
Chinese Regulations Are Working—Why Is Surface Ozone Over Industrialized Areas Still High? Applying Lessons From Northeast US Air Quality Evolution
Authors: Chen Xiaokang , Jiang Zhe , Shen Yanan , Li Rui , Fu Yunfei , Liu Jane , Han Han , Liao Hong , Cheng Xugeng , Jones Dylan B. A. , Worden Helen , Abad Gonzalo González
Published: July 2021

Observational data indicate increasing trends of surface ozone (O3) in China, despite emission controls that have resulted in reductions of precursor emissions. Here, we explore the cause of this contradiction, through analysis of surface observations (2014–2019) in China and historical observation record in the United States (US, 1990–2019). Our observation‐based analysis indicates that the reductions of nitrogen oxides (NOx) emissions led to increase of surface O3 in North China Plain (NCP) and Yangtze River Delta (YRD) of around 8 ppb. However, NOx controls resulted in shift of O3 chemical regimes over NCP and YRD, with turning points between NOx‐ and volatile organic compound (VOC)‐limited regimes around 2019, while model simulations suggest transitional or NOx‐limited regimes over the rest of China. The impacts of high fine particles (PM2.5) on O3 formation has declined because of the reduction of PM2.5 concentrations. Stricter NOx controls can mitigate O3 pollutions over industrialized areas in China.
Anthropogenic Impacts on Tropospheric Reactive Chlorine Since the Preindustrial
Authors: Zhai Shuting , Wang Xuan , McConnell Joseph R. , Geng Lei , Cole‐Dai Jihong , Sigl Michael , Chellman Nathan , Sherwen Tomás , Pound Ryan , Fujita Koji , Hattori Shohei , Moch Jonathan M. , Zhu Lei , Evans Mat , Legrand Michel , Liu Pengfei , Pasteris Daniel , Chan Yuk‐Chun , Murray Lee T. , Alexander Becky
Published: July 2021

Tropospheric reactive gaseous chlorine (Cly) impacts the atmosphere's oxidation capacity with implications for chemically reduced gases such as methane. Here we use Greenland ice‐core records of chlorine, sodium, and acidity, and global model simulations to show how tropospheric Cly has been impacted by anthropogenic emissions since the 1940s. We show that anthropogenic contribution of nonsea‐salt chlorine significantly influenced total chlorine and its trends after the 1940s. The modeled regional 170% Cly increase from preindustrial to the 1970s was driven by acid displacement from sea‐salt‐aerosol, direct emission of hydrochloric acid (HCl) from combustion, and chemical reactions driven by anthropogenic nitrogen oxide (NOx) emissions. Since the 1970s, the modeled 6% Cly decrease was caused mainly by reduced anthropogenic HCl emissions from air pollution mitigation policies. Our findings suggest that anthropogenic emissions of acidic gases and their emission control strategies have substantial impacts on Cly with implications for tropospheric oxidants, methane, and mercury.
On Contributions of Multiscale Dynamic Processes to the Steric Height in the Northeastern South China Sea as Revealed by Moored Observations
Authors: Miao Mingfang , Zhang Zhiwei , Qiu Bo , Liu Zhiyu , Zhang Xincheng , Zhou Chun , Guan Shoude , Huang Xiaodong , Zhao Wei , Tian Jiwei
Published: July 2021

Based on 2‐year moored measurements in the northeastern South China Sea, contributions of multiscale dynamic processes to steric height (SH) at 60 m are quantified. It shows that on average, root‐mean‐squared (RMS) SHs of mesoscales, submesoscales, diurnal and semidiurnal internal tides (ITs), and supertidal internal gravity waves (IGWs) are 7.56, 1.01, 1.19, 2.84, and 1.46 cm, respectively, with their respective relative contributions of 53.8%, 7.2%, 8.5%, 20.2%, and 10.4%. The SHs of ITs and supertidal IGWs are dominated by stationary and nonstationary components, respectively. Seasonally, mesoscales and submesoscales show larger RMS SHs in winter than summer but the opposite occurs for ITs and supertidal IGWs. Although the RMS SH of submesoscales exceeds nonstationary ITs in winter, it is much smaller than the sum of nonstationary ITs and supertidal IGWs. Therefore, to detect submesoscales using SWOT data, approaches to remove the SHs of nonstationary ITs and supertidal IGWs are called for.
X‐Discontinuity Beneath the Indian Shield—Evidence for Remnant Tethyan Oceanic Lithosphere in the Mantle
Authors: Srinu Uppala , Kumar Prakash , Haldar C. , Kumar M. Ravi , Srinagesh D. , Illa Bhaskar
Published: July 2021

Beneath the continents and island arcs, a seismic discontinuity is often detected around 300 km depth, referred to as the X‐discontinuity. Various mineralogical and petrological mechanisms have been put forth to explain its occurrence. Because of the large depth variability, it is challenging to explain its origin invoking a single mineralogical phase transition. In order to investigate this discontinuity beneath India, we analyzed 10,216 P wave receiver functions at seismological stations deployed on the Indian shield and the Himalayas. We detect the X‐discontinuity as a sporadic and thin feature, in the depth range of 246–335 km, with a sharp shear velocity jump of 2.5%–3.6%. It neither bears a clear tectonic affinity nor has any correlation with the transition zone discontinuities. Interpreting its origin due to a single mineralogical change warrants a large spatial variation in the mantle temperature. Therefore, we suggest that the observed widespread X‐discontinuity beneath the Indian shield owes its origin to two mechanisms, that is, Orthoenstatite to high pressure Clinoenstatite transformation which shifts to lower pressures (∼2 GPa) due to the presence of water (0.13 wt% H2O) in MgSiO3 and coesite‐stishovite transition occurring at 8–11 GPa due to excess silica in an eclogitic component derived from the Tethys oceanic lithosphere subducted during lower Eocene. The identification of such a discontinuity could allow tracking of subducted material within the upper mantle providing a measure of mantle geochemical heterogeneity.
Assessing Margin‐Wide Rupture Behaviors Along the Cascadia Megathrust With 3‐D Dynamic Rupture Simulations
Authors: Ramos Marlon D. , Huang Yihe , Ulrich Thomas , Li Duo , Gabriel Alice‐Agnes , Thomas Amanda M.
Published: July 2021

From California to British Columbia, the Pacific Northwest coast bears an omnipresent earthquake and tsunami hazard from the Cascadia subduction zone. Multiple lines of evidence suggests that magnitude eight and greater megathrust earthquakes have occurred ‐ the most recent being 321 years ago (i.e., 1700 A.D.). Outstanding questions for the next great megathrust event include where it will initiate, what conditions are favorable for rupture to span the convergent margin, and how much slip may be expected. We develop the first 3‐D fully dynamic rupture simulations for the Cascadia subduction zone that are driven by fault stress, strength and friction to address these questions. The initial dynamic stress drop distribution in our simulations is constrained by geodetic coupling models, with segment locations taken from geologic analyses. We document the sensitivity of nucleation location and stress drop to the final seismic moment and coseismic subsidence amplitudes. We find that the final earthquake size strongly depends on the amount of slip deficit in the central Cascadia region, which is inferred to be creeping interseismically, for a given initiation location in southern or northern Cascadia. Several simulations are also presented here that can closely approximate recorded coastal subsidence from the 1700 A.D. event without invoking localized high‐stress asperities along the down‐dip locked region of the megathrust. These results can be used to inform earthquake and tsunami hazards for not only Cascadia, but other subduction zones that have limited seismic observations but a wealth of geodetic inference.
Uplift and Seismicity Driven by Magmatic Inflation at Sierra Negra Volcano, Galápagos Islands
Authors: Bell Andrew Forbes , Hernandez Stephen , La Femina Peter Christopher , Ruiz Mario Calixto
Published: July 2021

Although episodes of surface uplift and elevated seismicity precede many volcanic eruptions, their temporal evolution is often complex, and apparently in contradiction to simple trends predicted by mechanical deformation models. Here, we use continuous global positioning system and seismic data recorded at Sierra Negra volcano, Galápagos Islands, to show how the edifice responded to stress changes driven by magma accumulation in a shallow sill. The rate of uplift varied during the 13 years and 6.5 m of inflation before the 2018 eruption. The number of earthquakes per unit of uplift increased exponentially with total uplift as the differential stress increased. Accordingly, the temporal seismicity rate varied in time as a function of both the total uplift and the uplift rate. The Gutenberg‐Richter b‐value decreased as a function of total uplift. In the final six months before the eruption, a sequence of large (M > 4) earthquakes regulated the state of stress on the fault, each being followed by 2–3 days of postseismic quiescence, and retarding the increase in seismicity rate. These earthquakes did not affect the overall uplift rate. Subsidence of 8.5 m accompanied the 2‐month eruption. On resumption of uplift, the number of earthquakes per unit of uplift was very low, and the b‐value high, reflecting the relaxed stress state of the fault system. These observations show that crustal deformation becomes increasingly brittle at higher stress states, and supports theoretical models based on elastic‐brittle mechanics. They suggest that joint interpretation of deformation and seismicity is key for forecasting future eruptions in similar volcanic settings.
GPS Imaging of Global Vertical Land Motion for Studies of Sea Level Rise
Authors: Hammond William C. , Blewitt Geoffrey , Kreemer Corné , Nerem R. Steven
Published: July 2021

We estimate the rates and patterns of vertical land motion (VLM) on all locations on Earth's land surface using GPS Imaging. The solution is based on a large database of uniformly processed GPS data from solutions that are aligned to the International Terrestrial Reference Frame. We provide global maps and estimates of VLM at all tide gauges of the Permanent Service for Mean Sea Level to better constrain the difference between geocentric and relative sea level rise. To enable critical assessment of the VLM estimate, the temporal and spatial contributions to rate uncertainty and variability are generated and included for every gauge. Seasonality and trends of uplift are assessed and found to be strongly correlated with observations from gravity data suggesting that loading from the terrestrial hydrosphere is a dominant driver of non‐glacial isostatic adjustment (non‐GIA) VLM. Although stations are dominantly concentrated at subsiding parts of continents, GPS Imaging geographically balances VLM signals, correcting for bias associated with network distribution. This allows us to make a global assessment of the budget of uplift and subsidence attributable to GIA and non‐GIA sources. We show that the surface motion of the continents is on average upward, implying that the unobserved areas (composed of the ocean basins and ice‐covered areas) move on average downward with respect to Earth center. However, after correcting for the GIA the reverse is true, and observed areas subside on average implying that the unobserved areas undergo net non‐GIA‐related uplift.
Position, Magnitude, and Size of Warm‐Pool El Niño: Variability, Seasonal Predictability, and Climate Impacts
Authors: Cheung Paxson K. Y. , Leung Marco Y. T. , Zhou Wen
Published: July 2021

This study surveys the variability and predictability of the position, magnitude, and size of warm‐pool El Niño (WP El Niño), as well as its impacts on the climate. A new detection method for WP El Niño that is flexible regarding its position, magnitude, and size is developed. Thirteen WP El Niño events are found from 1950 to 2018 using this detector. These events have a mean (standard deviation) center position of 31.7 (12.4)° longitude, a mean peak sea surface temperature anomaly (SSTA) of 1.87 (0.62) K, and a zonal size parameter of 19.99 (5.13)° longitude. Also, stronger WP El Niño events tend to be larger and take place farther east. Based on these distributions, a set of model experiments is conducted to evaluate climate sensitivity to these three features. The wintertime North American temperature dipole due to WP El Niño is chosen as an example. Its bearing is linearly controlled by the position of the SSTA field of WP El Niño, and this control is stronger when the SSTA field is stronger or smaller. Predictability of position, magnitude, and size of WP El Niño on seasonal scale by the North American Multi‐Model Ensemble is examined. With a 2‐month lead‐time, the position and magnitude of WP El Niño are predicted accurately, but size tends to be large‐biased. Increasing the lead‐time generally leads to more eastward bias, cold bias, and large bias. Precision of the predictions is also reduced with lead‐time.