bluuebunny/crossref_metadata_2025 huggingface dataset:
Italo-Mycenaean and other Aegean-influenced pottery in Late Bronze Age Italy: the case for regional production
Authors: Jones Richard E. , Levi Sara T. , Bettelli Marco , Cannavò Valentina
Published: January 2021

Decorated Italo-Mycenaean (IM) pottery, a high-status class found and made over three centuries from the Italian Late Middle Bronze Age onwards, was the subject of a large archaeological and archaeometric enquiry published by the present authors in 2014. The present paper focuses on identifying IM’s centres of production. The results of chemical analysis of IM using mainly ICP-ES make a strong case for regional production, irrespective of findspots in several parts of Italy. This accords well with the relative stylistic individuality of IM observed among the finds of IM across many parts of Italy, suggesting that IM is a powerful archaeological indicator of the way local communities were constructing and negotiating their identities at this crucial time of social and economic change at the end of the Bronze Age. A picture of more dispersed intra-regional production emerges from the combined chemical and petrographic analysis of two other pottery classes displaying Aegean influence: wheel-made Grey ware and decorated Final Bronze Age/Early Iron Age (FBA/EIA) pottery from sites in present-day Apulia and from Broglio di Trebisacce in Calabria. Potters manufacturing the former applied their knowledge of the wheel and kiln firing to handmade impasto shapes which were largely shared by local communities within a region. The results obtained for the latter reflect demands of the new elites of the emerging FBA/EIA in southern Italy to create symbols expressing a new cultural identity: this pottery’s style, especially of Protogeometric, was uniform but its production was localised.
Improving diagnostics of rare genetic diseases with NGS approaches
Authors: Vinkšel Mateja , Writzl Karin , Maver Aleš , Peterlin Borut
Published: January 2021

According to a rough estimate, one in fifteen people worldwide is affected by a rare disease. Rare diseases are therefore common in clinical practice; however, timely diagnosis of rare diseases is still challenging. Introduction of novel methods based on next-generation sequencing (NGS) technology offers a successful diagnosis of genetically heterogeneous disorders, even in case of unclear clinical diagnostic hypothesis. However, the application of novel technology differs among the centres and health systems significantly. Our goal is to discuss the impact of the implementation of NGS in the diagnosis of rare diseases and present advantages along with challenges of diagnostic approach. Systematic implementation of NGS in health systems can significantly improve the access of patients with rare diseases to diagnosis and reduce the dependence of national health systems for cross-border collaboration.
Assessing the efficacy of the Tiger Stamp: a policy tool approach
Authors: Murray Sheridan Kate , Brewitt Peter Kimball
Published: January 2021

International conservation presents a unique challenge for American conservation agencies, demanding unique policy tools. To encourage American citizens to support overseas conservation, the Fish and Wildlife Service, the United States Postal Service, and environmental non-governmental organizations collaborated to create the Save Vanishing Species Stamp, a semipostal stamp featuring a tiger. In doing this, these actors relied on the flagship species approach, wherein a charismatic species attracts attention and support for ecological protection. The “Tiger Stamp” has been on sale since 2011, but its effectiveness as a policy tool is uncertain. In this paper, we discuss the Tiger Stamp and analyze its effectiveness from several angles. The stamp’s impact on species conservation is uncertain and its sales have been lower than those of past semipostal stamps, but this should be understood in the context of nationwide decline in traditional postal activities and the hortatory effect of the stamp beyond its economic effects. We conclude that the stamp is, on balance, a valuable policy tool, and should be continued.
Structures, Chemical Conversions, and Cytotoxicity of Tricholopardins C and D, Two Tricholoma Triterpenoids from the Wild Mushroom Tricholoma pardinum
Authors: Shi Chen , Peng Yue-Ling , He Juan , Li Zheng-Hui , Liu Ji-Kai , Feng Tao
Published: January 2021

Two undescribed Tricholoma triterpenoids, namely tricholopardins C (1) and D (2), were isolated from the wild mushroom Tricholoma pardinum. Their structures with absolute configurations were elucidated by spectroscopic methods, as well as the single crystal X-ray diffraction. Compounds 1 and 2 were further obtained by chemical conversions from the known analogues. Compound 1 showed significant cytotoxicity to MCF-7 and Hela cell lines with IC50 values of 4.7 μM and 9.7 μM, respectively. Its mechanism of inducing MCF-7 cell apoptosis was studied briefly.

Graphical Abstract
Multi-objective genetic algorithm optimization of linear proportional solenoid actuator
Authors: Wang Shi Jie , Weng Zhi Dan , Jin Bo , Cai Hong Xu
Published: January 2021

Linear proportional solenoid (LPS) is widely applied in different linear motion control systems as the electromagnetic actuator since its high reliability and low cost. LPS is difficult to optimize by changing a single variable due to amounts of structural design parameters, and each design parameter has a nonlinear relationship with the static electromagnetic force. This paper aims to improve LPS’s push force and response performance through magnetostatic finite element analysis (FEA) by ANSYS MAXWELL. This study compares FEA 2D model, 3D model and measurement results underrated coil current to verify the accuracy of FEA 2D model. In order to reveal the nonlinear relationship between shape design parameters and electromagnet design objectives, this study compares the influence degree of each variable on each design objective by conventional type LPS 2D FEA model. And for the purpose of improving LPS’s push force and response performance, a multi-objective optimization method has been proposed in this study based on genetic algorithm (GA) and magnetostatic FEA 2D model for optimizing the shape design parameters. All the study results were validated in both static conditions and dynamic conditions. The comparison between manufactured optimal type and conventional type results shows that the static push force in working stroke is improved 30.1%, displacement step response rise time is reduced 5.2% and 43.4%, and force step response rise time is reduced 20.5% and 44.6% with different return spring stiffness. Above all, LPS static and dynamic performance has been improved directly and the validation of proposed optimization method is verified in this paper.
Melanotan Tanning Injection: A Rare Cause of Priapism
Authors: Mallory Chase W. , Lopategui Diana M. , Cordon Billy H.
Published: January 2021

Melanotan II, an injectable melanocortin analog, is illicitly available on the internet to generate a sunless tan through melanocyte induction. It is also used as a sexual stimulant in unlicensed performance enhancement clinics, and has been investigated as a possible treatment agent in erectile dysfunction. We describe in this case report a patient presenting with acute ischemic priapism after subcutaneous injection of melanotan II. The patient was initially managed with cavernosal aspiration and irrigation, and intracavernous injection of phenylephrine without achieving detumescence. After failing initial management, the patient underwent operative management with penoscrotal decompression, a promising alternative technique for the management of refractory ischemic priapism. Priapism after melanotan II injection has only been reported in the literature twice before. This case report highlights a rare presentation of acute ischemic priapism after melanotan II use, managed with surgical decompression. Future therapeutic applications of these agents and updated management guidelines should consider priapism as a possible side effect.

CW. Mallory, DM Lopategui, BH. Cordon. Melanotan Tanning Injection: A Rare Cause of Priapism. Sex Med 2021;9:100298.
Saxo Grammaticus
Authors: Muceniecks André Szczawlinska
Published: January 2021

Denmark of the twelfth to thirteenth centuries was a place of transitions, and this volume analyzes that period through the lens of the 'Gesta Danorum' of Saxo Grammaticus and other sources. The 'Gesta' defends not only hierocratic conceptions but the Danish hegemonic project in the Baltic - which was grounded in the crusade movements. Such movements are presented through complex language and imagery about a glorious past brought to bear on the projects in the thirteenth century while internal tensions strengthen the monarchic and ecclesiastical institutions.
Colonial Memory
Authors: De Mul Sarah , Mul Sarah de
Published: January 2021

Exploring the intersections of memory, gender, and the postcolonial, Colonial Memory explores the phenomenon of colonial memory through the specific genre of women's travel writing. Building on criticism of memory and travel writing, Sarah De Mul seeks to open Dutch literature to postcolonial themes and concepts and to insert the history of the Dutch colonies and its critical recollection into the traditionally Anglophone-dominated field of postcolonial studies.

A vividly conceived and theoretically astute reading of the complicated weavings between the past and present involved in memory work and the process of nostalgic return. Elleke Boehmer, University of Oxford
War of Words
Authors: Kuitenbrouwer Vincent
Published: January 2021

The Boer War gripped the Dutch public during the turn of the nineteenth century, when the Boer Republics, made up of descendants of seventeenth-century settlers from the Netherlands, were fighting the British Empire in South Africa. War of Words examines the ample Dutch propaganda during this time period, which attempted to counterweigh the British coverage of the war. Vincent Kuitenbrouwer offers a highly readable study of the pro-Boer movement in the Netherlands both during the Boer War and far into the twentieth century, while exploring the representation of South Africans in Dutch-language publications and the several persistent stereotypes that colored the Dutch attitude toward the Boers.
This Cannot Happen Here
Authors: Braber Ben
Published: January 2021

This sweeping work is the first comprehensive English-language study of Jewish resistance in the Netherlands during World War II. Adopting a comparative approach, Ben Braber explores the situation of Jews in the Netherlands against the backdrop of their experiences in other Western European countries. Charting the occurrences of Jewish resistance, he pays particular attention to the ways in which the integration of Jews into Dutch society influenced their responses to German persecution. Braber's incisive analyses shed new light on Dutch and Jewish history, pointing the way toward future paths of inquiry.
Lard, Lice and Longevity
Authors: Futselaar Ralf , Ying-Hui Hsieh
Published: January 2021

Lard, Lice and Longevity reconstructs economic policies implemented in Denmark and the Netherlands during the German occupation. It clearly shows that the experiences of both these countries during World War I, and during the 1930s equipped them to introduce extensive and intrusive economic controls to ward off a subsistence crisis.

In spite of the strong similarities between the two countries in terms of policies and economic order, there remains a glaring difference between the two. Throughout the occupation years, the Netherlands suffered a markedly higher level of child mortality than before or after the war, caused by an upsurge of infectious diseases. Child health in Denmark, on the other hand, declined during the occupation years, and infectious diseases rose only marginally there. In spite of similar policies, hence, the outcome in terms of the biological standard of living was dissimilar.

By closely investigating the impact of various policies on everyday life, and the amounts of goods available to different groups of consumers, this study identifies the causes of this remarkable divergence.
Conflicting Approaches to the U.S. Common Law of Foreign Official Immunity
Authors: Bradley Curtis A.
Published: January 2021

For more than a decade, U.S. courts have struggled to develop a common law immunity regime to govern suits brought against foreign government officials, and they are now divided on a number of issues, including the extent to which they should defer to the executive branch and whether to recognize a jus cogens exception. This Editorial Comment considers a more conceptual division in the courts, between an “effect-of-judgment” approach that would confer immunity only when the judgment that the plaintiff is seeking would be directly enforceable against the foreign state, and a broader “nature-of-act” approach that would confer immunity whenever the plaintiff's case is challenging conduct carried out on behalf of the state. The Comment argues in favor of the nature-of-act approach and explains why analogies in this context to domestic civil rights litigation are misplaced.
Rethinking Derogations from Human Rights Treaties
Authors: Helfer Laurence R.
Published: January 2021

Numerous governments have responded to the COVID-19 pandemic by declaring states of emergency and restricting individual liberties protected by international law. However, many more states have adopted emergency measures than have formally derogated from human rights conventions. This Editorial Comment critically evaluates the existing system of human rights treaty derogations. It analyzes the system's problems, identifies recent developments that have exacerbated these problems, and proposes a range of reforms in five areas—embeddedness, engagement, information, timing, and scope.
The BEAMISH hot water drill system and its use on the Rutford Ice Stream, Antarctica
Authors: Anker Paul G. D. , Makinson Keith , Nicholls Keith W. , Smith Andrew M.
Published: January 2021

During the 2018/19 Antarctic field season, the British Antarctic Survey (BAS) Basal conditions on Rutford Ice Stream: BEd Access, Monitoring and Ice Sheet History’ (BEAMISH) project drilled three holes through the Rutford Ice Stream, West Antarctica. At up to 2154 m, these are the deepest hot water drilled subglacial access holes yet created, enabling the recovery of sediment from the subglacial environment, and instrumenting the ice stream and its bed. The BEAMISH hot-water drill system was built on extensive experience with the BAS ice shelf hot-water drill and utilises many identical components. With up to 1 MW of heating power available, the hot water drill produces 140 L min−1of water at 85°C to create a 300 mm diameter access hole to the base of the ice stream. New systems and processes were developed for BEAMISH to aid critical aspects of deep access drilling, most notably the creation of cavities interlinking boreholes at 230 m below the surface and enabling water recirculation throughout the deep drilling operations. The modular design of the BEAMISH drill offers many benefits in its adaptability, redundancy, and minimal logistical footprint. These design features can easily accommodate the modifications needed for future deep, clean access hole creation in the exploration of subglacial environments.
Providing to belong: masculinities, hustling and economic uncertainty in Nairobi ‘ghettos’
Authors: van Stapele Naomi
Published: January 2021

Hustling as a concept has travelled through the global soundscapes of impoverished, neglected, racialized and otherwise marginalized urban settings. The widespread rearticulation of the term ‘hustling’ in a broad range of urban languages reveals that its use in particular forms of Black Atlantic music cultures speaks to shared experiences worldwide. Simultaneously, it shows the flexibility of this term to acquire new and unfolding meanings. This article focuses on the modes in which poor young men in Nairobi (re)deploy, translate and practise hustling to fit immediate circumstances and imagine possible futures, and on the meanings these men produce in the process. I argue that interrogating hustling as a practice provides insights into gendered experiences of urban life worlds in the underserved and highly policed areas of Nairobi, which may tentatively resonate with young men in comparable positions worldwide. I specifically examine how positions of (junior) manhood are configured by localized hustling practices to elucidate how navigating fear and hope, while facing extreme uncertainty, simultaneously defines and undermines their sense of manhood.
‘We are taught to act’: hustling on the move in Kampala and Nairobi
Authors: Monteith William , Mirembe George
Published: January 2021

This article explores the question of what happens when highly socialized and contingent forms of provisioning go wrong, and young men are forced to start again in unfamiliar urban contexts. The decline of George Mirembe's moneylending business in Kampala pre-empted his departure from the country and his arrival in Nairobi in search of new socio-economic opportunities. Lacking the documents and language skills necessary to enter formal sectors of the economy, George claimed asylum as a sexual refugee while working as a smuggler and a voice actor in the shadow film industry. His activities illustrate the advantages and limitations of the hustle as a framework for understanding the activities of transnational ‘others’ in African cities. I argue that translational practices of acting and storytelling have become a generalized tactic of survival among migrants in urban East Africa. Such practices are illustrative of a form of ‘uprooted hustle’ – or hustling on the move – that is oriented towards individual survival and exit rather than place-based transformation.
Burying “Zik of Africa”: The Politics of Death and Cultural Crisis
Authors: Adebanwi Wale
Published: January 2021

This article uses the death and burial of one of the most important political leaders in twentieth-century Africa, and Nigeria's first and only ceremonial president, Rt. Hon. (Dr.) Nnamdi Azikiwe, to reflect on how and why the deaths and burials of significant persons in Africa represent occasions for the (re)production and management of cultural crises. It argues that the extant literature on the death of consequential persons in Africa either understates or overlooks the generalizability of the “essential contestability” of the material and immaterial relations of the past, present, and future provoked by such deaths. This is particularly visible when these relations are disturbed or challenged by the absence of the person and the process of their burial or reburial.
Toward a Comparative History of Racial Thought in Africa: Historicism, Barbarism, Autochthony
Authors: Glassman Jonathon
Published: January 2021

Using material from the history of African thought, this essay proposes a strategy for writing a comparative history of race that ranges beyond a consideration of white supremacy and its anti-racist inflections. Studies of race outside the global north have often been hobbled by rigid modernist assumptions that over-privilege the determining influence of Western discourses at the expense of local intellectual inheritances. This essay, in contrast, proposes a focus on locally inherited discourses of difference that have shown signs of becoming racialized, at times through entanglement with Western ideas. It pays particular attention to discourses that arranged “human kinds” along a progression from barbarian to civilized, suggesting the presence of African historicisms that in modern times have converged with the stadial ideas that played a major role in Western racial thought.
Parsing preferences and individual differences in nonnative sentence processing: Evidence from eye movements
Authors: Cheng Yesi , Rothman Jason , Cunnings Ian
Published: January 2021

Using both offline and online measures, the present study investigates attachment resolution in relative clauses in English natives (L1) and nonnatives (L2). We test how relative clause resolution interacts with linguistic factors and participant-level individual differences. Previous L1 English studies have demonstrated a low attachment preference and also an “ambiguity advantage” suggesting that L1ers may not have as strong a low attachment preference as is sometimes claimed. We employ a similar design to examine this effect in L1 and L2 comprehension. Offline results indicate that both groups exhibit a low attachment preference, positively correlated with reading span scores and with proficiency in the L2 group. Online results also suggest a low attachment preference in both groups. However, our data show that individual differences influence online attachment resolution for both native and nonnatives; higher lexical processing efficiency correlates with quicker resolution of linguistic conflicts. We argue that the current findings suggest that attachment resolution during L1 and L2 processing share the same processing mechanisms and are modulated by similar individual differences.
The Spectre of the Present: Time, Presentism and the Writing of Contemporary History
Authors: Colla Marcus
Published: January 2021

Presentism used to be so simple. In the old vernacular it referred to a tendency to view the past from the perspective of the present (or, at its most extreme, maybe even use the past to illuminate the present). Historians disagreed furiously on the intellectual virtues of orienting their views of the past to the needs of the current day. But the content of the term itself was rarely disputed.
Světlana: Partisans and Power in Post-War Czechoslovakia
Authors: Markham Mira
Published: January 2021

After the renewal of national independence in 1945 former anti-fascist partisans were among the Czechoslovak Communist Party's most reliable and radical allies. Nevertheless, following the communist coup of 1948, a group of partisans in the rural region of Moravian Wallachia began to mobilise wartime networks and tactics against the consolidating party dictatorship, establishing the Světlana resistance network. Simultaneously, state authorities also drew on partisan practices to reconstitute opposition and resistance in this region as evidence of an international conspiracy that could be understood and prosecuted within the framework of official ideology and propaganda. This article analyses the case of Světlana to examine the politics of people's democracy in Czechoslovakia and explore local dynamics of resistance and repression during the early years of the communist regime.
The first evidence of intersexuality in Atka mackerel Pleurogrammus monopterygius (Hexagrammidae)
Authors: Zhukova Kristina , Golovatyuk Galina Yu.
Published: January 2021

Histological examination of Atka mackerel ovotestes reveals the possibility of intersexuality. Individuals with bisexual gonads have been caught in the North Pacific near the south-east coast of the Kamchatka peninsula. While intersex appeared to be normal females with developing ovaries, histological analysis showed the presence of both female and male tissue in the same gonad. Specifically, primary growth, cortical alveolar and primary vitellogenic oocytes were located among spermatogonia cysts. The prevalence of intersexuality in the population was less than 0.1%.
Optimization of ultraviolet irradiation of Clarias gariepinus (Burchell, 1822) eggs for androgen production
Authors: Okomoda Victor Tosin , Nursyaza Haziqah Jumahat , Samuel Ijabo Oga , Hassan Anuar , Oladimeji Abraham Sunday , Abol-Munafi Ambok Bolong , Alabi Korede Isaiah , Ikhwanuddin Mhd
Published: January 2021

The optimum distance and duration of ultraviolet (UV) irradiation for the complete inactivation of African catfish Clarias gariepinus egg nucleus was investigated in this study. The UV light was suspended above the unfertilized eggs at four distances (5, 10, 20 and 30 cm) and for five durations (1, 2, 3, 4 and 5 min). Then, the irradiated eggs were activated with sperm from diploid C. gariepinus and cold shocked at 5°C for 5 min just moments before cell cleavage. Ploidy analysis was performed using karyotype chromosome counting. The results obtained suggested that the further the distance, the better the hatchability rate, however prolonged duration seemed to significantly reduced hatchability. All treatments with surviving progenies at the end of the study showed evidence of successfully diploid gynogen (2n = 56) induction at different percentages. However, the optimal protocol that gave a moderately high hatchability/survival rate and completely induced gynogens was exposure of the eggs to UV irradiation at 20 cm for 1 min. It was concluded that the distance and duration of UV irradiation affects gynogenetic induction in African catfish C. gariepinus.
Induced reproduction and early development in dourado,Salminus franciscanusLima & Britski, 2007 (Pisces: Characiformes)
Authors: Paschoalini Alessandro Loureiro , Eloi Mariana Rodrigues , dos Santos José Enemir , dos Santos José Cláudio Epaminondas , Rizzo Elizete , Bazzoli Nilo
Published: January 2021

Our study aimed to establish the response ofSalminus franciscanusto hypophysation and describe the main morphological events of its embryonic process. Wild fish were captured in São Francisco River and selected broodstock (females: 66.4 ± 11.1 cm and 4.04 ± 2.32 kg; males: 58.3 ± 10.2 cm and 3.62 ± 1.12 kg) were kept at 26.1 ± 0.6°C for induction of final maturation/gamete release via the hypophysation technique. In females, two doses (0.8 and 5.6 mg/kg body weight) of crude pituitary extract of common carp (Cyprinus carpio) were administered with a 14 h interval. For males, a single dose (2.7 mg/kg body weight) of crude pituitary extract was applied at the same time as the females’ second dose. Oocytes and sperm were manually stripped 8 h after a females’ second hormonal dose. Fertilization was carried out using the dry method. Eggs were kept in funnel-type 60 L incubators at 24.3 ± 0.3°C and were analyzed and photographed every 10 min. After hormonal induction, 60% of females and 100% of males reacted positively and no broodstock mortality was recorded. The females released an average of 385.2 ± 78.4 g of oocytes and the fertilization rate observed was 50.4 ± 12.3%. The blastopore closure occurred at 7.5 h, somite formation at 12 h and hatching at 20 h post-fertilization. In general, the results of this study improve the understanding of the reproductive biology of dourado and confirm its potential for fish farming in the neotropical region.
Of Ebbs and Flows: Understanding the Legal Consequences of Granting Personhood to Natural Entities in India
Authors: Jolly Stellina , Menon K.S. Roshan
Published: January 2021

A study of the rights regime for environmental protection in India indicates that such protections overlap with constitutional rights guaranteed primarily to citizens or persons under the law. Contemporary jurisprudence has aggressively developed this intersectionality, declaring natural entities to be living persons with fundamental rights analogous to those of human beings. This article explores the role played by two judgments delivered by the Uttarakhand High Court –Mohammed Salimv.State of UttarakhandandLalit Miglaniv.State of Uttarakhand– in the establishment of an effective framework for environmental protection. This is effectuated in both cases by assigning legal personality to rivers and articulating a conceptual shift from the human-centric approach. Accounting for the socio-cultural and spiritual relationships that have received legal protection, this article critically analyzes the judgments, their rationale and contributions to environmental protection. As the judgments articulate a paradigm shift in environmental protection, their effectiveness is best assessed through analyzing the frameworks created for their implementation. While the pronouncement of the Indian courts on the legal personality of rivers is an encouraging paradigm shift in environmental commitment, establishing the rights of nature was undertaken without due attention to the complexities that characterize the Indian socio-politico-religious context and to the legal consequences of bestowing vaguely contoured rights upon natural entities.
Sensitivity of 21st Century Ocean Carbon Export Flux Projections to the Choice of Export Depth Horizon
Authors: Palevsky Hilary I. , Doney Scott C.
Published: January 2021

Global Earth system model simulations of ocean carbon export flux are commonly interpreted only at a fixed depth horizon of 100 m, despite the fact that the maximum annual mixed layer depth (MLDmax) is a more appropriate depth horizon to evaluate export‐driven carbon sequestration. We compare particulate organic carbon (POC) flux and export efficiency (e‐ratio) evaluated at both the MLDmax and 100‐m depth horizons, simulated for the 21st century (2005–2100) under the RCP8.5 climate change scenario with the Biogeochemical Elemental Cycle model embedded in the Community Earth System Model (CESM1‐BEC). These two depth horizon choices produce differing baseline global rates and spatial patterns of POC flux and e‐ratio, with the greatest discrepancies found in regions with deep winter mixing. Over the 21st century, enhanced stratification reduces the depth of MLDmax, with the most pronounced reductions in regions that currently experience the deepest winter mixing. Simulated global mean decreases in POC flux and in e‐ratio over the 21st century are similar for both depth horizons (8%–9% for POC flux and 4%–6% for e‐ratio), yet the spatial patterns of change are quite different. The model simulates less pronounced decreases and even increases in POC flux and e‐ratio in deep winter mixing regions when evaluated at MLDmax, since enhanced stratification over the 21st century shoals the depth of this horizon. The differing spatial patterns of change across these two depth horizons demonstrate the importance of including multiple export depth horizons in observational and modeling efforts to monitor and predict potential future changes to export.
Periodicity Analysis of Earthquake Occurrence and Hypocenter Depth Near Parkfield, California, 1994–2002 Versus 2006–2014
Authors: Dutilleul Pierre , Johnson Christopher W. , Bürgmann Roland
Published: January 2021

In central California, periodic earthquake occurrence suggests a relationship with annual hydrological, atmospheric, thermal, and tidal loadings. In catalogs of declustered earthquakes within 100 km from Parkfield, CA, we study a semiannual periodicity for the monthly number of ≤7.2‐km‐deep earthquakes and the monthly median hypocenter depth over 1994–2002 and 2006–2014. Peak‐trough months in fitted periodic components differ between time spans and event populations. Deeper earthquakes present no semiannual and a weak annual periodicity. Although modeled pore pressure shows a Spring peak, when added to the elastic Coulomb stress from surface hydrospheric loads, it fails to predict a 6‐month periodicity for 2006–2014. In 1994–2002, the pore‐pressure amplitude appears to be of same order as the elastic stress and may have had a stronger effect. In 2006–2014, we did not find load model parameters explaining the observed pattern or apparent changes following the 2003 San Simeon and 2004 Parkfield earthquakes.
Hazard From Endogenous Gas Emissions and Phreatic Explosions in Rome City (Italy)
Authors: Carapezza Maria Luisa , Barberi Franco , Tarchini Luca , Ranaldi Massimo
Published: January 2021

A gas blowout during an unauthorized well drilling occurred on June 9, 2020 at the Rome‐Ciampino boundary at the periphery of Colli Albani quiescent volcano. This zone hosts a shallow confined gas‐pressured aquifer, which recently produced further three gas blowouts. Dangerous atmospheric CO2 and H2S concentrations killed some birds, and 12 families were evacuated. The helium isotopic composition indicates that the gas has a magmatic origin. It rises toward the surface along leaky faults, pressurizing the shallow confined aquifer and creating a permanent gas blowout hazard. Colli Albani volcano is characterized by anomalous uplift, release of magmatic gas, and episodic seismic crises. Should a volcanic unrest occur, gas hazard would increase in this densely inhabited zone of Rome city, as the input of magmatic gas into the confined aquifer might create overpressure conditions leading to a harmful phreatic explosion, or increase the emission of hazardous gas through newly created fractures.
Cancellation of the Precessional Cycle in δ18O Records During the Early Pleistocene
Authors: Morée Anne L. , Sun Tianyi , Bretones Anaïs , Straume Eivind O. , Nisancioglu Kerim , Gebbie Geoffrey
Published: January 2021

The dominant pacing of glacial‐interglacial cycles in deep‐ocean δ18O records changed substantially during the Mid‐Pleistocene Transition. The precessional cycle (∼23 ky) is absent during the Early Pleistocene, which we show can be explained by cancellation of the hemispherically antiphased precessional cycle in the Early Pleistocene interior ocean. Such cancellation develops due to mixing of North Atlantic and Southern Ocean δ18O signals at depth, and shows characteristic spatial patterns. We explore the cancellation potential for different North Atlantic and Southern Ocean deep‐water source δ18O values using a tracer transport ocean model. Cancellation of precession occurs for all signal strengths and is widespread for a signal strength typical for the Early Pleistocene. Early Pleistocene precessional power is therefore likely incompletely archived in deep‐sea δ18O records, concealing the true periodicity of the glacial cycles in the two hemispheres.
Radial Evolution of a CIR: Observations From a Nearly Radially Aligned Event Between Parker Solar Probe and STEREO‐A
Authors: Allen R. C. , Ho G. C. , Mason G. M. , Li G. , Jian L. K. , Vines S. K. , Schwadron N. A. , Joyce C. J. , Bale S. D. , Bonnell J. W. , Case A. W. , Christian E. R. , Cohen C. M. S. , Desai M. I. , Filwett R. , Goetz K. , Harvey P. R. , Hill M. E. , Kasper J. C. , Korreck K. E. , Lario D. , Larson D. , Livi R. , MacDowall R. J. , Malaspina D. M. , McComas D. J. , McNutt R. , Mitchell D. G. , Paulson K. W. , Pulupa M. , Raouafi N. , Stevens M. L. , Whittlesey P. L. , Wiedenbeck M.
Published: January 2021

The addition of Parker Solar Probe (PSP) to the Heliophysics System Observatory has allowed for the unprecedented ability to study Corotating Interaction Regions (CIRs) at multiple radial distances without significant temporal/longitudinal variations. On September 19, 2019, PSP observed a CIR at ∼0.5 au when it was nearly radially aligned with the Solar Terrestrial Relations Observatory‐Ahead (STEREO‐A) spacecraft at ∼1 au, allowing for an unambiguous assessment of the radial evolution of a single CIR. Bulk plasma and magnetic field signatures of the CIR evolve in a fashion characteristic to previous observations; however, the suprathermal ions are enhanced over a larger longitudinal range at PSP than at STEREO‐A, although at much lower intensities. The longitudinal spread appears to be largely a consequence of magnetic field line topology at CIRs between the compressed slow solar wind upstream and high‐speed stream following the CIR, underscoring the importance of the large‐scale topology of these structures.
The Global Distribution of Craters With Alluvial Fans and Deltas on Mars
Authors: Wilson Sharon A. , Morgan Alexander M. , Howard Alan D. , Grant John A.
Published: January 2021

We present an inventory of alluvial fans and deltas within martian impact craters based on a systematic global survey of Context Camera images. Our database includes 314 fan‐hosting craters, with a total of 890 alluvial fans and 114 deltas. Alluvial fans and deltas are more widespread than previously reported (∼40°N to 54°S) and are strongly banded with respect to latitude. Most craters with alluvial fans occur at higher elevations (10°S–30°S) and along the dichotomy boundary (0°–10°N). Deltas occur at lower elevations (0°–40°N) where access to groundwater may have enabled the formation of lakes, and to a lesser extent in the highlands (0°–30°S). Alluvial fans in southern mid‐latitude craters preferentially formed along the northern and southern walls, which may reflect climatic control through solar insolation. The widespread distribution within the observed latitude bands and the similar Hesperian to Amazonian age of alluvial fan‐hosting craters is consistent with late‐stage synoptic precipitation.
Seeing Through the Atmosphere of Venus: What Is on the Surface?
Authors: Cloutis Edward A.
Published: January 2021

The exploration of the surface geology of Venus has been hampered by its inhospitable conditions and thick and opaque atmosphere. Fundamental properties, such as crustal composition and heterogeneity remain poorly constrained. Multiple analytical techniques are required to better understand its geology. A spectroscopy‐based laboratory study of the emissivity properties of Venus‐relevant igneous rocks, measured at 440°C by Dyar, Helbert, Maturilli, et al. (2020; https://doi.org/10.1029/2020GL090497) shows that the use of multiple atmospheric windows in the 1‐µm region can provide strong constraints on the FeO content of Venus‐relevant igneous rocks, and by extension, the type of igneous rock. These results will help improve our ability to map the surface geology of Venus remotely.
Biological Cohesion as the Architect of Bed Movement Under Wave Action
Authors: Chen Xindi , Zhang Changkuan , H. Townend Ian , Paterson David M. , Gong Zheng , Jiang Qin , Feng Qian , Yu Xiping
Published: January 2021

Cohesive extracellular polymeric substances (EPS) generated by microorganisms abundant on Earth are regarded as bed “stabilizers” increasing the erosion threshold in sedimentary systems. However, most observations of this phenomenon have been taken under steady flow conditions. In contrast, we present how EPS affect the bed movement under wave action, showing a destabilization of the system. We demonstrate a complex behavior of the biosedimentary deposits, which encompasses liquefaction, mass motion, varying bed formations and erosion, depending on the amount of EPS present. Small quantities of EPS induce higher mobility of the sediments, liquefying an otherwise stable bed. Bed with larger quantities of EPS undergoes a synchronized mechanical oscillation. Our analysis clarifies how biological cohesion can potentially put coastal wetlands at risk by increasing their vulnerability to waves. These findings lead to a revised understanding of the different roles played by microbial life, and their importance as mediators of seabed mobility.
Postseismic Deformation due to the 2012 Mw 7.8 Haida Gwaii and 2013 Mw 7.5 Craig Earthquakes and its Implications for Regional Rheological Structure
Authors: Tian Zhen , Freymueller Jeffrey T. , Yang Zhiqiang
Published: January 2021

Observations of ∼7 years of postseismic deformation following the 2012 M
w 7.8 Haida Gwaii and 2013 M
w 7.5 Craig earthquakes in western British Columbia and southeastern Alaska provides insight into the regional rheologic structure and seismological hazards. A stress‐driven afterslip‐only model cannot alone explain rates or spatial patterns of the far field and later stage postseismic deformation measured by Global Positioning System (GPS). We thus develop an integrated model that fits the observations by combining afterslip on the deeper extension of the faults and distributed viscous flow in the asthenosphere. The best‐fit integrated model has a 60‐km thick lithosphere overlying a Burgers body asthenosphere with a Maxwell viscosity of 2 × 1019 Pa s (0.8–3 × 1019 Pa s at 95% confidence), with a Kelvin viscosity assumed equal to 10% of that value. These values are in good agreement with rheological models derived from glacial isostatic adjustment data. The early, near‐field postseismic deformation from both events is dominated by their corresponding afterslip, however, throughout the Craig postseismic period, the dominant mechanism in the far field is viscoelastic relaxation. For the intermediate region between the two earthquakes, both events contribute to the observed postseismic displacements. Because there was no obvious afterslip following the Haida Gwaii event or known large historical earthquakes on the southernmost part of the QCF, this region continues to have great potential to suffer a large earthquake in the future.
Mantle Heterogeneity and Melting Processes in the South China Sea: Thermal and Melting Models Constrained by Oceanic Crustal Thickness and Basalt Geochemistry
Authors: Zhang Xubo , Lin Jian , Behn Mark D.
Published: January 2021

We simulate mantle flow, thermal structure, and melting processes beneath the ridge axis of the South China Sea (SCS), combining the nominally anhydrous melting and fractional crystallization model, to study mantle heterogeneity and basin evolution. The model results are constrained by seismically determined crustal thickness and major element composition of fossil ridge axis basalts. The effects of half‐spreading rate, mantle potential temperature, mantle source composition, and the pattern of melt migration on the crustal thickness and magma chemical composition are systematically investigated. For the SCS, the east and southwest (SW) subbasins have comparable crustal thickness, but the east subbasin has higher FeO and Na2O contents compared to the SW subbasin. The estimated best fitting mantle potential temperatures in the east and SW subbasins are 1,360 ± 15 °C and 1,350 ± 25 °C, respectively. The mantle in the east subbasin (site U1431) prior to the cessation of seafloor spreading is composed primarily of the depleted mid‐ocean ridge basalt mantle (DMM), and is slightly contaminated by eclogite/pyroxenite‐rich component. However, the mantle source composition of the SW subbasin (sites U1433 and U1434) contains a small percentage (2–5%) of lower continental crust. Basalt samples at the northern margin of the east subbasin (site U1500) shows similar chemical characteristics with that of the SW subbasin. We suggest that the basin‐scale variability in the mantle heterogeneity of the SCS can be explained by a single model in which the contamination by the lower continental crust is gradually diluted by melting of DMM as the ridge moves away from the rifted margin.
Multiple, Coeval Silicic Magma Storage Domains Beneath the Laguna Del Maule Volcanic Field Inferred From Gravity Investigations
Authors: Trevino Sarah F. , Miller Craig A. , Tikoff Basil , Fournier Dominique , Singer Brad S.
Published: January 2021

The rhyolite‐producing Laguna del Maule volcanic field (LdMVF), Chile, has had numerous post‐glacial eruptions that produced large explosions and voluminous lava flows. During the Holocene ∼60 m of surface uplift is recorded by paleo‐shorelines of the fresh‐water Laguna del Maule, with an inflation source near the Barrancas volcanic complex. Rhyolites from the Barrancas complex erupted over ∼14 ka including some of the youngest (1.4 ± 0.6 ka) lava flows in the field. New gravity data collected on the Barrancas complex reveals a residual gravity low (−6 mGal, “Barrancas anomaly”) that is distinct from the pronounced gravity low (−19 mGal; “Lake anomaly”) associated with present‐day ground uplift to the northwest. Three‐dimensional inversion of the Barrancas anomaly indicates the presence of a magma body with a maximum density contrast with the host rock of −250 kg/m3 centered at a depth of ∼3 km below surface. Nearby Miocene high‐silica granites represent frozen remnants of highly evolved rhyolitic magma. Comparison of the densities measured from samples of these plutons with the geophysical model densities, and integration of thermodynamic modeling of silicic melt evolution, provide constraints on our interpretation. We propose a magma body, containing <30% melt phase and low volatile content, exists beneath Barrancas. The Barrancas and Lake gravity lows represent magma in different physical states, associated with past and present‐day storage beneath LdMVF. The gravity model mirrors geochemical observations which independently indicate that at least two distinct rhyolites were generated and stored as discrete magma bodies within the broader LdMVF.
B‐Positive: A Robust Estimator of Aftershock Magnitude Distribution in Transiently Incomplete Catalogs
Authors: van der Elst Nicholas J.
Published: January 2021

The earthquake magnitude‐frequency distribution is characterized by the b‐value, which describes the relative frequency of large versus small earthquakes. It has been suggested that changes in b‐value after an earthquake can be used to discriminate whether that earthquake is part of a foreshock sequence or a more typical mainshock‐aftershock sequence, with a decrease in b‐value heralding a larger earthquake to come. However, the measurement of b‐value during an active aftershock sequence is strongly biased by short‐term incompleteness of the earthquake catalog and by data‐windowing, and these biases have the same direction as the proposed signal. Here I develop a new estimator of the b‐value that is insensitive to transient changes in catalog completeness and that does not require data windowing. The new estimator “b‐positive” is based on the positive‐only subset of the differences in magnitude between successive earthquakes, which are described by a double‐exponential (Laplace) distribution with the same b‐value as the magnitude distribution itself. The b‐positive estimator greatly improves the robustness of continuous b‐value measurements during active earthquake sequences, as well as in historical catalogs with unknown or variable completeness. The new estimator confirms some of the observations of Gulia and Wiemer (2019), although at a reduced level, showing a decrease and recovery of the b‐value during several recent foreshock sequences that cannot be attributed simply to measurement bias. However, the unbiased b‐value changes may be too subtle to use in a real‐time earthquake alarm system.
Reaction‐Induced Fracturing: When Chemistry Breaks Rocks
Authors: Renard François
Published: January 2021

Reaction‐induced fracturing occurs when fluid‐rock interactions lead to the growth of a mineral phase that produces a volume increase, which perturbs the stress field and can cause fracturing in the surrounding rock. This process may occur with a positive feedback loop because, as more fractures are formed, more water can infiltrate the pore space, enhancing the kinetics of reaction. Yoshida et al. (2020, https://doi.org/10.1029/2020JB020268) have studied and modeled reaction‐induced fracturing in oceanic rocks collected during the Oman Drilling Project. These rocks have been intensively hydrated by a process called serpentinization, which has profound geodynamic implications. The authors couple detailed microstructural observations and numerical modeling of reaction‐induced fracturing that incorporates permeability evolution. Building on the outcomes of their study, I discuss here the current knowledge of the reaction‐induced fracturing process, in which chemical forces control rock fracture in various geological environments. Based on recent experimental results and molecular dynamics simulations, I discuss the conditions under which reaction‐induced fracturing may either self‐amplify or slow down and even stop.