bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

SummaryThe 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

SummaryOur 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

AbstractA 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

AbstractGlobal 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

AbstractIn 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

AbstractA 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

AbstractThe 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

AbstractThe 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

AbstractWe 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

AbstractThe 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

AbstractCohesive 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

AbstractObservations 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

AbstractWe 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

AbstractThe 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

AbstractThe 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

AbstractReaction‐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.