bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvement of osseointegration by recruiting stem cells to titanium implants fabricated with 3D printing
Authors: Bollman Mary , Malbrue Raphael , Li Chunhong , Yao Hong , Guo Shengmin , Yao Shaomian
Published: October 2019

Slow and incomplete osseointegration and loss of osseointegration are major problems in dental and bone implants. We designed implants with interconnected 3D‐tubulous structures and hypothesized that such interconnecting 3D (I3D) structures would serve as a repository for chemoattractants to recruit stem cells to promote osseointegration. A concept Laser Mlab‐cusing‐R laser‐powder‐bed‐fusion (LPBF) 3D printing system was used to produce titanium implants with designed features. The implants were loaded (coated) with stromal cell–derived factor‐1 alpha (SDF‐1α), and subjected to stem cell recruitment. Implants were then surgically transplanted into the rabbit skull bone. After 12 weeks, osseointegration was analyzed by reverse‐torque test and the implants were examined for calcium deposition by Alizarin Red staining. The I3D implants attracted significantly more stem cells than solid implants when coated (loaded) with SDF‐1α. Greater torque force was needed to extract the I3D implants with 200 and 300 µm I3D structures than to extract solid implants from the skull. Generally, more calcium deposition was observed on the I3D implants than on the solid counterparts. LPBF 3D printing can be used to fabricate implants with complex structures. I3D‐tubulous structures of implants can retain chemoattractant for recruitment of stem cells to enhance osseointegration.
Performance of the Linox implantable cardioverter defibrillator leads: A single‐center experience
Authors: Marai Ibrahim , Milman Anat , Nof Eyal , Gurevitz Osnat , Barlev David , Lipchenca Igor , Bachar Sharona , Glikson Michael , Beinart Roy
Published: October 2019

Background

An early failure of Biotronik Linox implantable cardioverter defibrillator (ICD) leads has been reported from several centers.

Aim

To compare the performance of Linox ICD leads with different other ICD leads as a report of the Sheba Medical Center experience.

Methods

All patients who had implantation of Linox ICD leads between 2007 and 2016 were included in this study. ICD lead failure was defined as low‐ or high‐voltage impedance; failure to capture, sense, or defibrillate; or the presence of nonphysiological signals not due to external interference. The survival probability of Linox leads was determined and compared to Medtronic Sprint Quattro ICD leads.

Results

A total of 340 patients (age 64.4 ± 1.8 years) were included in this analysis. They were followed up to 105 months (mean 45.7 ± 7, median 44 (Interquartile range (IQR) 26‐63) months). Twelve patients (3.5%) met the criteria for lead failure within 61.2 ± 22.9 months (median 66.5 [IQR 48–85 months]) post implantation. Noise with inappropriate ventricular arrhythmias detection, with or without therapy, was seen in 10 patients (83%). High pacing thresholds and high impedances were detected in two patients (17%). The survival probability of Linox leads at 60 months (97.3%) was similar to the survival probability of Sprint Quattro leads (98.2%) (P = .58). Nevertheless, the survival probability at 105 months was much lower (81% vs 97%, Linox ICD lead and Sprint Quattro lead, respectively, P = .0039).

Conclusion

Linox ICD leads have higher late failure rates compared to Sprint Quattro leads. These findings need to be confirmed in larger scale studies.
Polls and Elections Trump, Twitter, and Public Dissuasion: A Natural Experiment in Presidential Rhetoric
Authors: Miles Matthew R. , Haider‐Markel Donald P.
Published: October 2019

Research suggests that the ability of the president to influence public attention to issues and shape public opinion is limited. Recently, presidential efforts at persuasion have expanded to social media, but presidential persuasion has yet to be explored in this medium. We address two relevant questions. First, what effects does a presidential tweet have on public interest in the issue discussed in the tweet? Second, what effect does a presidential tweet have on public attitudes about that issue? To answer these questions, we utilize a natural experiment that occurred while we were fielding a nationally representative survey of American adults. Our analysis provides considerable evidence that presidential tweets can have the unintended consequence of driving the public away from the president’s position on an issue.
Inhibitory control moderates the quadratic association between resting respiratory sinus arrhythmia and prosocial behaviors in children
Authors: Zhang Runzhu , Wang Zhenhong
Published: October 2019

Resting respiratory sinus arrhythmia (RSA) is thought to be an important physiological correlate of prosocial behaviors. A negative quadratic association between resting RSA and prosocial behaviors has been found in recent studies. However, it remains unknown whether inhibitory control (IC), as an aspect of cognitive regulation, moderates this quadratic association. This issue was examined in the present study. One hundred and forty‐eight children (81 girls, 54.7%) aged 7–8 years completed a go/no‐go task to assess their IC, and the children's parents completed the Strengths and Difficulties Questionnaire‒Chinese version (SDQ‐CV) to assess children's prosocial behaviors. Resting RSA was calculated by electrocardiogram (ECG) data collected during a resting period in the laboratory. The results showed a significant quadratic association between resting RSA and children's prosocial behaviors. More importantly, IC had a significant moderating effect on the quadratic association between resting RSA and prosocial behaviors. Specifically, the quadratic effect of resting RSA on prosocial behaviors was observed only among children with low and average IC and disappeared in children with better IC. The findings suggest that IC interacts with resting RSA to contribute to prosocial behaviors in children. High levels of IC could attenuate the negative impact of high and low resting RSA on prosocial behaviors.
Unraveling the dynamics of a ground‐dwelling beetle population exposed to quarry exploitation and restoration practices
Authors: Eufrázio Sofia , Oliveira Amália , Miralto Otília , Medinas Denis , Silva Carmo , Sá Cátia , Mira António , Salgueiro Pedro A.
Published: October 2019

Quarry exploitation and restoration practices are expected to have overarching and contrasting impacts on animal communities. Although many studies describe these impacts, they generally overlook the effects on population dynamics and individual movements. We assessed the impacts of quarry exploitation and restoration activity on population dynamics, individual movement, and habitat use of a sand‐dwelling specialist beetle (Scarites cyclops). The study was performed on three plots: one adjacent to the margin of quarry exploitation, another subjected to restoration practices, and a control plot with no disturbance. A capture‐mark‐recapture approach was undertaken to estimate population parameters, movement, and habitat use. In the exploitation plot S. cyclops exhibited lower probability of recapture and lower apparent survival, as well as many movements fleeing away from quarry limits. Habitat suitability modeling showed that the exploitation plot provided better habitat conditions for the species than the restoration plot. It exhibited higher bare ground cover with scattered clumps of vegetation and higher proportions of fine sand (<0.4 mm). In the restoration plot, S. cyclops population showed a lower abundance, with a higher rate of recaptures, and a more limited dispersal ability of the individuals. There is an apparent early stage of colonization by S. cyclops in the restoration plot, but movements may already be hampered by unsuitable habitat restoration (higher herbaceous cover and different soil texture). We suggest preserving suitable habitat patches in the vicinity of the impacted areas and providing dispersal routes. Beyond vegetation, soil texture must be considered to allow local animal communities to establish in restored areas.
The problem of regulatory arbitrage: A transaction cost economics perspective
Authors: Marjosola Heikki
Published: October 2019

Regulatory arbitrage, or the ability of financial firms to circumvent or neutralize rules, is a classic problem of financial regulation. This article draws on transaction cost economics (TCE) to reformulate this old problem, thus defining regulatory arbitrage as a contracting hazard arising from interactions between the regulator and regulated firms, given bounded rationality and opportunism. Following standard TCE, the article first characterizes the implicit regulatory contract in finance, focusing in particular on the mobile and elastic nature of regulated actors and financial assets as well as the contested utility of financial innovation. It is then argued that this incomplete and hazard‐prone regulatory bargain must be matched with a governance structure that both adapts to unforeseen circumstances and avoidance strategies and copes with radical uncertainty about the welfare consequences of financial innovation. To that end, the article discusses how a governance structure here termed “relational regulation” might facilitate suchex postgovernance under uncertainty.
The relationship between morphological awareness and reading comprehension in Spanish‐speaking children
Authors: D'Alessio María Josefina , Jaichenco Virginia , Wilson Maximiliano A.
Published: October 2019

In the last decades, a series of studies has explored the role of morphological awareness on reading comprehension. Path analysis studies performed in English have shown that morphological awareness benefits reading comprehension both directly and indirectly, through word decoding. This issue has seldom been explored in Spanish. The aim of this study was to replicate in Spanish the results previously found in English. We used path analysis to assess three alternative models of the relationship between morphological awareness, word decoding and reading comprehension in 4th grade Spanish‐speaking children. Contrary to English, we found that morphological awareness benefits reading comprehension only directly. We conclude that in Spanish, in which accurate and fluent pronunciation of written words can be achieved through grapheme‐to‐phoneme conversion rules, morphological awareness does not help the correct pronunciation of words. Thus, morphological awareness is not relevant for word decoding in Spanish but is related to reading comprehension since this type of morphological knowledge provides access to the semantic and syntactic information of new words.
Combined tube cystostomy and urethrotomy for the treatment of urethral obstruction due to urolithiasis in goats
Authors: Applegate Tanya J. , Barrell Emily A. , Hassel Diana M. , Hackett Eileen S. , Simpson Katharine M. , Callan Robert J.
Published: October 2019

Objective

To describe the treatment of goats with urethral obstruction secondary to urolithiasis by combining tube cystostomy and urethrotomy.

Animals

Eight male goats.

Study design

Short case series.

Methods

Medical records (September 2012–September 2017) of male goats treated for obstruction secondary to urolithiasis with tube cystostomy and urethrotomy were reviewed. Data collected included signalment, history, physical examination findings, diagnostic results, perioperative treatments, operative details, hospitalization duration, intraoperative and postoperative complications, urolith analysis, and time to restoration of urethral patency. Long‐term follow‐up (>12 months) was obtained by email or telephone interviews of owners or by clinical examination.

Results

Seven of eight goats were castrated males of various of breeds. All goats were tachycardic with urethral pulsation at admission. Uroliths were composed of calcium carbonate in four goats and silica in one goat. All goats regained urethral patency during hospitalization, and all were discharged alive from the hospital. Seven goats were alive at long‐term follow‐up. Postoperative complications included persistent urethral obstruction requiring a second urethrotomy 2 days postoperatively, premature dislodgement of the bladder catheter and jejunal obstruction secondary to adhesions, and recurrence of obstructive urolithiasis within the proximal perineal urethra requiring a second surgery 8 months later (1 each). Long‐term outcome was good, with urethral patency beyond 12 months in six of eight goats.

Conclusion

Combining tube cystostomy and urethrotomy restored urethral patency in goats with urethral obstruction from uroliths. Although none of the complications seemed directly related to the urethrotomy, formation of abdominal adhesions and recurrence of urolithiasis affected long‐term outcomes.

Clinical significance

Uroliths that do not dissolve in acidic urine may be more frequent in some practices. The combined approach of tube cystostomy and urethrotomy appears to successfully restore urethral patency with promising long‐term outcomes.
Estimating the Value of a Unitization Law for Shale Gas Development
Authors: Kleit Andrew , Leelachutipong Eakasit , Wang John Yilin
Published: October 2019

Horizontal drilling together with hydraulic fracturing has become a very effective mechanism for the extraction of natural gas in several shale plays in the United States. Efficient horizontal drilling, however, generally requires operating in a “unit,” across the property of numerous landowners. If a landowner, however, is unwilling to allow drilling beneath their property, the result can be harmful to both the producing company and other landowners in the unit. To address this problem, most major oil and nature gas states, except for Pennsylvania, have unitization statutes. We examine the impact of such laws by looking at the recent Emersyn matter from the state of Ohio. We estimate that the unitization ordered by the State of Ohio greatly increased the potential recoverable product from the proposed unit. Just as importantly, it more than proportionally increased the profits to the producer and royalty owners. Our results also show that the breakeven production price is very sensitive to whether forced unitization is available to the producer. At least three policy issues arise from this analysis. First, the rationale for unitization is not clear in all circumstances. In the Emersyn matter, the State of Ohio required access to property rights, even though not allowing such access would not have “stranded” any other landowners, and where the party in question was a sophisticated producer, rather than a landowner. Second, there appears to be no guidance for setting reimbursements to property owners who are forced to allow producers access to their property. Third, it is not clear the extent to which the state should take the producers' plans as given, rather than inquire about options to unitization.
Study on the Optimization of Hydrate Management Strategies in Deepwater Gas Well Testing Operations
Authors: Song Shangfei , Shi Bohui , Yu Weichao , Ding Lin , Liu Yang , Li Wang , Gong Jing
Published: October 2019

Low temperature and high pressure conditions favor the formation of gas clathrate hydrates which is undesirable during oil and gas industries operation. The management of hydrate formation and plugging risk is essential for the flow assurance in the oil and gas production. This study aims to show how hydrate management in the deepwater gas well testing operations in the South China Sea can be optimized. To prevent the plugging of hydrate, three hydrate management strategies are investigated. The first method, injecting thermodynamic hydrate inhibitor (THI) is the most commonly used method to prevent hydrate formation. THI tracking is utilized to obtain the distribution of mono ethylene glycol (MEG) along the pipeline. The optimal dosage of MEG is calculated through further analysis. The second method, hydrate slurry flow technology is applied to the gas well. Pressure drop ratio (PDR) is defined to denote the hydrate blockage risk margin. The third method is the kinetic hydrate inhibitor (KHI) injection. The delayed effect of KHI on the hydrate formation induction time ensures that hydrates do not form in the pipe. This method is effective in reducing the injection amount of inhibitor. The problems of the three hydrate management strategies which should be paid attention to in industrial application are analyzed. This work promotes the understanding of hydrate management strategies and provides guidance for hydrate management optimization in oil and gas industry.
Plasma-enhanced atomic layer deposition of vanadium nitride
Authors: Kozen Alexander C. , Sowa Mark J. , Ju Ling , Strandwitz Nicholas C. , Zeng Guosong , Babuska Tomas F. , Hsain Zakaria , Krick Brandon A.
Published: October 2019

This work describes process development and associated characterization of a plasma-enhanced atomic layer deposition process for vanadium nitride (VN) using tetrakis(dimethylamido)vanadium and nitrogen plasma over a deposition temperature range from 150 to 300 °C. The authors characterize these films using x-ray photoelectron spectroscopy, x-ray diffraction, spectroscopic ellipsometery, and tribological measurements to determine the films' chemistry, structure, and wear resistance. Overall, they demonstrate a stable VN growth window between 250 and 350 °C, with deposition temperatures below this leading to incomplete reaction between the precursors. Film crystallinity increases with increasing deposition temperature based on the VN cubic (020) peak area increase. Atomic layer deposition VN films show excellent tribological properties with an average wear rate of 7.7 × 10−8 mm3/N m and a friction coefficient of 0.38.
Evaluation of the Dawson function and its antiderivative needed for the Gaussian broadening of piecewise polynomial functions
Authors: Vohánka Jiří , Nečas David , Franta Daniel
Published: October 2019

The broadening of a sharp (unbroadened) dielectric function is a fruitful approach to the construction of models of dielectric response of materials. It naturally includes structural disorder or finite state lifetime and allows parameterization of such effects. The unbroadened function is often taken as a piecewise polynomial. Broadening it with the Lorentzian then leads to relatively simple analytical formulae. The Gaussian broadening, however, requires evaluation of several special functions, including the antiderivative of the Dawson function which is not generally available in mathematical libraries. Recently, the authors described the simple recurrent formulae for the construction of a Gaussian-broadened piecewise polynomial model of a complex dielectric function using three special functions, the error function, the Dawson function, and its antiderivative. In this paper, for the Dawson function and its antiderivative an efficient evaluation method is developed enabling the utilization of this model in optical spectra fitting. The effectiveness of this approach is illustrated using elementary and real-world examples of complex dielectric function models.
Multichannel processing of vibrational measurements: A constrained subspace application
Authors: Candy J. V. , Case J. E. , Fisher K. A. , Eves K. L. , Foster M. M. , Kumar P. , Bower D. E. , Illingworth B. R. , Emmons M. C.
Published: October 2019

Monitoring mechanical systems operating in uncertain environments contaminated with both environmental disturbances and noise lead directly to low signal-to-noise-ratios, creating an extremely challenging processing problem, especially in real-time. In order to estimate the performance of a particular system from uncertain vibrational data, it is necessary to identify its unique resonant (modal) frequency signature. The monitoring of structural modes to determine the condition of a device under investigation is essential, especially if it is a critical entity of an operational system. The development of a model-based scheme capable of the on-line tracking of the inherent structural modal frequencies by applying both constrained subspace identification techniques to extract the modal frequencies and state estimation methods to track the evolution is discussed. An application of this approach to a cylindrical structural device (pipe-in-air) is analyzed based on theoretical simulations along with controlled validation experiments, including injected anomalies illustrate the approach and performance. Statistics are gathered to bound potential processors for real-time performance employing these constrained techniques.
Long-Term Effects of Whole-Body Vibration in Trained Adolescent Swimmers: Does It Increase Strength, Power, and Swimming Performance?
Authors: Muniz-Pardos Borja , Gómez-Bruton Alejandro , Matute-Llorente Ángel , González-Agüero Alex , Gómez-Cabello Alba , Casajús José A. , Vicente-Rodríguez Germán
Published: October 2019

Purpose: To examine the effects of a 6-month whole-body vibration (WBV) training on lower-body strength (LBS), lower-body power (LBP), and swimming performance in adolescent trained swimmers. Methods: Thirty-seven swimmers (23 males and 14 females; 14.8 [1.3] y) were randomly assigned to the WBV (n = 20) or the control group (n = 17). Isometric LBS (knee extension and half squat) and LBP (vertical and horizontal jumps and 30-m sprint) tests were performed before and after the intervention period. Swimming performance times in 100 m were collected from official competitions. As time × sex interaction was not found for any variable (P > .05), males and females were analyzed as a whole. Results: Within-group analyses showed a most likely beneficial moderate effect of WBV on isometric knee extension (effect size [ES] = 0.63), 30-m sprint test (ES = 0.62), and 100-m performance (ES = 0.25), although these were corresponded with comparable small to moderate effects in the control group (ES = 0.73, 0.71, and 0.20, respectively). The control group obtained a small possibly beneficial effect of swimming-only training on vertical jump performance, whereas no effect was observed in the WBV group. Unclear effects were observed for the rest of the variables assessed. Between-group analyses revealed unclear effects of WBV training when compared with the control condition in all studied variables. Conclusions: There is no current evidence to support the use of WBV training, and therefore, coaches and sports specialists should select other methods of training when the aim is to increase LBS, LBP, or swimming performance.
Structural dispersion–based reduction of loss in epsilon-near-zero and surface plasmon polariton waves
Authors: Li Yue , Liberal Iñigo , Engheta Nader
Published: October 2019

Exploiting structural dispersion of waveguides, we explore how to reduce the effect of loss in ENZ and surface plasmon polariton.
A Dutch Case Report of Successful Treatment of Chronic Relapsing Urinary Tract Infection with Bacteriophages in a Renal Transplant Patient
Authors: Kuipers Saskia , Ruth Mike M. , Mientjes Mike , de Sévaux Ruud G. L. , van Ingen Jakko
Published: October 2019

We report a case of a 58-year-old renal transplant patient who developed a recurrent urinary tract infection with an extended-spectrum β-lactamase (ESBL)-positive
Klebsiella pneumoniae
strain in the first month posttransplant. Even though it tested susceptible to carbapenems and despite repeated meropenem treatment, his infection recurred. The infection eventually evolved into epididymitis that was successfully treated with meropenem and bacteriophages.
A Putative Microcin Amplifies Shiga Toxin 2a Production of Escherichia coli O157:H7
Authors: Mosso Hillary M. , Xiaoli Lingzi , Banerjee Kakolie , Hoffmann Maria , Yao Kuan , Dudley Edward G.
Published: October 2019

How the gut microflora influences the progression of bacterial infections is only beginning to be understood. Antibiotics are counterindicated for
E. coli
O157:H7 infections, limiting treatment options. An increased understanding of how the gut microflora directs O157:H7 virulence gene expression may lead to additional treatment options. This work identified
E. coli
strains that enhance the production of Shiga toxin by O157:H7 through the secretion of a proposed microcin. Microcins are natural antimicrobial peptides that target specific species, can act as alternatives to antibiotics, and mediate microbial competition. This work demonstrates another mechanism by which non-O157
E. coli
strains may increase Shiga toxin production and adds to our understanding of microcins, a group of antimicrobials less well understood than colicins.
Multistage growth and compositional change at the Goat Rocks volcanic complex, a major Pliocene–Pleistocene andesite center in the southern Washington Cascades
Authors: Wall Kellie T. , Grunder Anita L. , Miggins Daniel P. , Coble Matthew A.
Published: October 2019

The deeply eroded Goat Rocks volcanic complex was a major locus of andesitic volcanism in the Cascade arc in southwest Washington during the late Pliocene to Pleistocene. This volcanic complex includes the remnants of multiple andesitic edifices over an area of ~200 km2, centered ~35 km north of Mount Adams on the arc axis. New 40Ar/39Ar ages for seven samples and U/Pb zircon ages for nine samples indicate a 2.5–2.9 m.y. eruptive history at Goat Rocks. Four eruptive stages are delineated: Tieton Peak (potentially 3.0–2.6 Ma), Bear Creek Mountain (>1.6–1.3 Ma), Lake Creek (1.1–0.6 Ma), and Old Snowy Mountain (0.4–0.1 Ma), each named for the major vent that was active during that time. Lake Creek volcano was the most voluminous of these edifices and probably rose at least 3400 m above sea level with a volume of ~60 km3, comparable to nearby active composite volcanoes. Thirty new bulk composition X-ray fluorescence (XRF) and inductively coupled plasma–mass spectrometry analyses from the volcanic complex are presented, in addition to 54 previously unpublished XRF analyses for samples collected by Don Swanson. The compositional variability is greatest in the early and late stages, ranging from basaltic andesite to rhyolite, whereas the more voluminous middle stages are dominated by andesite to dacite. The middle eruptive stages are interpreted to have been a time of peak thermal energy with a mature subvolcanic plexus. In addition, compositions shift from high-K to medium-K compositions with time, which mimics variation across the arc; early eruptive products are similar in composition to those of Mount Adams, and Old Snowy Mountain stage compositions are more similar to those of Mount St. Helens. The life cycle of Goat Rocks volcanic complex provides new perspective on the longevity and evolution of major arc volcanoes, and on the complex distribution of magma in the Cascade arc at the latitudes of southern Washington and adjacent Oregon.
Dikes in the Koa‘e fault system, and the Koa‘e–east rift zone structural grain at Kīlauea Volcano, Hawai‘i
Authors: Swanson Donald A. , Fiske Richard S. , Thornber Carl R. , Poland Michael P.
Published: October 2019

Two small scoria vents were discovered in the Koa‘e fault system, an extensional regime connecting the east and southwest rift zones of Kīlauea that was previously considered to be noneruptive. The chemical composition of the scoria suggests an early to middle nineteenth-century age. The vents prove that magma can intrude several kilometers into the central part of the Koa‘e fault system from the nearest rift zone, supporting previous seismic and geodetic inferences of intrusions into the Koa‘e fault system in the twentieth century.

Geodetic studies for the past 50 yr document widening of the Koa‘e fault system at a time-averaged rate of ~4.5 cm/yr, involving mostly coseismic strains, but also creep and displacement related to dike intrusions. These rates are consistent with a longer-term widening rate for the past ~700 yr calculated from crack widths in a lava flow of about that age. The Koa‘e fault system blends into, and is a structural continuation of, the east rift zone. We interpret the locus of intrusion in the east rift zone to have migrated ~6.5 km SE during the past 100,000–125,000 yr, as estimated from linear extrapolation of measured displacement rates across the Koa‘e fault system and east rift zone. The inception of migration is consistent with the onset of the tholeiitic stage at Kīlauea as interpreted by previous studies. As the rift zone moved away from the summit, a marked curvature in the transport pathway developed in order for the rift zone to maintain its connection to the summit magma reservoir. The migration resulted in development of the SE-trending east rift connector, a term we prefer instead of the upper east rift zone. The connector supplies magma to the ENE-trending rift zone from the summit storage complex but is not itself the site of significant magma storage or eruption.

The Koa‘e fault system merges into the southwest rift zone, which has been migrating southeastward for an uncertain period of time. Some magma that enters it passes from the summit reservoir complex through the southwest rift connector (seismic southwest rift zone), analogous to the east rift connector. Both connectors reflect the response of magma-transport pathways to asymmetric volcano spreading away from a relatively fixed summit magma reservoir.

The ENE structural grain of the Koa‘e fault system and east rift zone pervades Kīlauea’s entire edifice. Most eruptions take place along this trend. The major exception is the southwest rift zone, which may reflect the stresses of Mauna Loa spreading and the Ka‘ōiki fault system. The dominant ENE grain emphasizes the importance of SSE-directed volcano spreading in controlling most of Kīlauea’s tectonic and eruptive behavior.
Geologic mapping, morphometric characterization, and statistical analyses of six venusian shield fields: Insights into the processes related to their formation
Authors: Nypaver* Cole , Lang† Nicholas P. , Thomson Bradley J.
Published: October 2019

Small shield volcanoes with basal diameters <20 km represent the most abundant type of volcano on Venus. These shield volcanoes number >>106 in population and often occur in clusters known as shield fields, which have been interpreted to be analogous to basaltic volcanic fields on Earth. Despite previous work on shield fields, questions related to edifice morphology and magma viscosity, timing relations of events across an individual field, volume of erupted material, and the role of tectonic structures are still unresolved. Here, we address those questions through geologic mapping, volumetric calculations, and statistical analysis of possible edifice alignments in six venusian shield fields: Asherat Colles, Chernava Colles, Monoshi Tholus, Nordenflycht Patera, Ran Colles, and Urutonga Colles. Our results indicate that all of these shield fields and their associated deposits are younger than the surrounding units within the mapping areas, and each field displays overlapping temporal relations with local extensional and contractional structures. Each field also displays a lack of a consistent pattern in the temporal distribution of volcanism with regards to edifice type. Analyses of possible edifice alignments suggest edifice trends that are consistent with mapped tectonic structures within all studied fields except Asherat Colles. Comparison of these six venusian fields to terrestrial basaltic volcanic fields shows that venusian fields may be up to two to three orders of magnitude larger in their areal expanse and volume of erupted material. Our results are consistent with previous interpretations of venusian shield fields representing low rates (likely <5 × 10−4 km3/yr) of magma supply feeding these magmatic centers and highlight the effects of the resolution limit of the Magellan data set on interpreting fundamental geologic processes on the venusian surface.
Taxonomy of Cretaceous–Paleogene coniferous woods and their distribution in fossil Lagerstätten of the high latitudes
Authors: Dolezych* M. , Reinhardt* L. , Kus* J. , Annacker* V.
Published: October 2019

Anatomical analyses of fossil woods, supplemented by information from coal petrographic investigations, provide data for reconstructing the Cretaceous–Paleogene, mostly swampy woodland vegetation of the high latitudes. This paper is focused on the taxonomic description of conifers that have been recovered from a number of plant fossil Lagerstätten in Nathorstland, Yukon North Slope–western Mackenzie Delta, Ellesmere Island, northern Trolleland, and Kotel’nyi Island. The investigation revealed a relatively low taxonomic diversity. Wood-anatomical identification of Taxodioxylon vanderburghii provides evidence for the genus Metasequoia. The determination of Glyptostroboxylon cf. rudolphii demonstrates the most likely presence of Glyptostrobus, and the genus Cunninghamia is proved by the identification of Glyptostroboxylon tenerum. Moreover, this first evidence of Cunninghamia in the high latitudes establishes this plant as an “Arctic conifer.” Piceoxylon laricinoides (Høeg) comb. nov., a new combination, is proposed for a fossil wood species that represents the genus Larix. Fossils identified as Protopiceoxylon woods, Protopiceoxylon sp., and Protopiceoxylon yukonense represent the extinct gymnospermous Protopinaceae group. A fossil forest from the Split Lake Lagerstätte focusing on the habitus of in situ trunks and stumps was reconstructed. The vegetation encompasses a succession with three stages, an Equisetum reed facies, a Metasequoia swamp forest facies, and a Larix swamp forest facies. The taxonomic investigation suggests a widely distributed zone of vegetation with various conifers in the high latitudes. The lignite samples are characterized by predominantly woody (xylite) tissues with well-preserved, mummified stems and roots and a variable content of liptinite macerals, mostly resinite and suberinite. The intensive yellow fluorescent textinite of characteristic zoned structures and distinct microspores was observed in all investigated lignites.
Subsidence, rapid inversion, and slow erosion of the Central Tertiary Basin of Svalbard: Evidence from the thermal evolution and basin modeling
Authors: Dörr N. , Lisker F. , Jochmann M. , Rainer T. , Schlegel A. , Schubert K. , Spiegel* C.
Published: October 2019

The Central Tertiary Basin (CTB) of Svalbard provides a rare opportunity for studying the sedimentary response to the Cenozoic evolution of the Barents Sea area. Here we present a basin model based on low-temperature thermochronology data, vitrinite reflectance measurements, and clay mineralogy from two drill cores inside the CTB. Our model suggests a tight relationship between the basin history and the regional geodynamic evolution. Enhanced heat flow during the Paleocene implies an extensional or transtensional origin of the basin, prior to Eurekan deformation. The first, compressional stage of the Eurekan orogeny was associated with rapid basin subsidence and high deposition rates, causing the coalification of the CTB hard coals. The second, transpressional stage of the Eurekan triggered rapid basin erosion and was associated with a decreasing heat flow. Onset of erosion is placed at ~45 ± 5 Ma, suggesting cessation of CTB deposition already by the late Early Eocene. Rapid erosion stopped coevally or just prior to the change to an extensional setting at the end of Eurekan deformation. Between ~40 and 10 Ma, the CTB experienced continuous slow erosion. From the Late Miocene onwards, erosion again accelerated, maybe related to lithospheric processes associated with northward propagation of the Knipovich Ridge. Estimates from our best-fit model suggest that nearly ~4 km of overburden was removed from the CTB since the end of Early Eocene.
Geochemical constraints on the provenance of pre-Mississippian sedimentary rocks in the North Slope subterrane of Yukon and Alaska
Authors: Nelson Lyle L. , Strauss Justin V. , Crockford Peter W. , Cox Grant M. , Johnson Benjamin G. , Ward William , Colpron Maurice , McClelland William C. , Macdonald Francis A.
Published: October 2019

The North Slope subterrane of Arctic Alaska extends from the northeastern Brooks Range of Alaska into adjacent Yukon, Canada, and includes a pre-Mississippian deep-water sedimentary succession that has been historically correlated with units exposed in the Selwyn basin of northwestern Laurentia. Sedimentary provenance data, including Sm-Nd isotopes and major and trace element geochemistry, provide detailed geochemical characterization of the regional pre-Mississippian strata of the North Slope subterrane. Combined with paleontological and geochronological age constraints, these new data record a marked shift in provenance in the Ordovician–Devonian(?) Clarence River Group, evidently linked to an influx of juvenile, arc-derived material. The timing and nature of this provenance change are consistent with early Paleozoic tectonic reconstructions of the Arctic margin that restore the North Slope subterrane to northeastern Laurentia (present coordinates), proximal to the Appalachian-Caledonian orogenic belt. Such a restoration requires significant post-Early Devonian sinistral strike-slip displacement to later incorporate the North Slope subterrane into the composite Arctic Alaska terrane.
Age, geochemistry, and significance of Devonian felsic magmatism in the North Slope subterrane, Yukon, Canadian Arctic
Authors: Ward William P. , Strauss Justin V. , Johnson Benjamin G. , McClelland* William C. , Colpron Maurice , von Gosen Werner , Piepjohn Karsten , Coble Matthew A. , Crockford Peter W. , Landis Joshua
Published: October 2019

New zircon U-Pb dates from the Mount Fitton, Mount Sedgwick, Mount Schaeffer, Old Crow, and Dave Lord plutons indicate that granitoids of the Old Crow plutonic suite in northern Yukon were emplaced in the North Slope subterrane of the Arctic Alaska composite terrane between 375 ± 2 Ma and 368 ± 3 Ma. Whole-rock major and trace element and Nd-Sr isotope geochemistry, combined with zircon trace element and Hf isotope geochemistry, indicate magma genesis involved significant contribution from older continental crust. Samples from the five plutons yield whole-rock εNd(t) values from -3.9 to -11.6 and 87Sr/86Sr(i) ratios of 0.7085–0.7444 and 0.8055. Zircon εHf(t) values range from -6.2 to -13.3. These North Slope subterrane granitoids are generally younger and isotopically more evolved than felsic rocks in the Coldfoot and Hammond subterranes of the southern Brooks Range (Arctic Alaska terrane), but in part are coeval with felsic rocks on the Seward and Chukotka peninsulas. The North Slope granitoids are also coeval and geochemically similar to arc magmatism in the Yukon-Tanana terrane in Yukon and on Axel Heiberg and northern Ellesmere islands, Nunavut. The Old Crow plutonic suite is interpreted as part of a Late Devonian arc system developed along the Arctic and Cordilleran margins. Late Devonian plutons were most likely emplaced after initial translation of the North Slope subterrane along the northern Laurentian margin. The plutons lie within or north of the Porcupine shear zone and thus do not limit post-Late Devonian displacement on the boundary between the North Slope subterrane and northwestern Laurentia.
Evidence for subtropical warmth in the Canadian Arctic (Beaufort-Mackenzie, Northwest Territories, Canada) during the early Eocene
Authors: Salpin Marie , Schnyder Johann , Baudin François , Suan Guillaume , Suc Jean-Pierre , Popescu Speranta-Maria , Fauquette Séverine , Reinhardt Lutz , Schmitz Mark D. , Labrousse Loïc
Published: October 2019

During the Paleocene–Eocene, the Earth experienced the warmest conditions of the Cenozoic and reduced equator-to-pole temperature gradients. Compared to low- and mid-latitude sites, Paleogene environmental changes are less documented in Arctic regions, although such high latitude areas constitute a critical domain to constrain global climate changes. Floral and faunal assemblages indicative of exceptionally warm and humid conditions during the late Paleocene–early Eocene have been reported in several localities around the Arctic Ocean. Additional studies are required to ascertain the effects of Paleocene–Eocene global environmental changes on western Arctic regions. Here we present multiproxy data from early Eocene deltaic plain sediments of the Mackenzie Delta (Canada). This environment is characterized by littoral forest, including swamp, showing that the mangrove Avicennia grew in Arctic Canada near 75°N under air temperatures averaging 21–22 °C annually and 10–14 °C in winter and with precipitation of 1200–1400 mm/yr. Kaolinite contents are high (up to 75% of clay assemblages), as under a modern subtropical climate. The Avicennia pollens recently found in the New Siberian Islands and in Arctic Canada imply that warm and wet conditions were widespread along the Arctic coast during the early Eocene. It also suggests a marine connection between the Arctic Basin and the mid-latitude oceans. We propose that an oceanic current must have connected the Arctic Basin to the Atlantic and/or Pacific and that an internal current developed in the Arctic Basin since the early Eocene.
Latest Cretaceous–early Eocene Pacific-Arctic?-Atlantic connection: Co-evolution of strike-slip fault systems, oroclines, and transverse fold-and-thrust belts in the northwestern North American Cordillera
Authors: Murphy* Donald C.
Published: October 2019

Comprehensive understanding of the pre-Paleogene kinematic evolution of the North American Cordillera in the context of evolving global plate interactions must begin with an understanding of the complex Late Cretaceous–early Eocene structural geometry and evolution of the northwestern Cordillera of Alaska, United States, and Yukon, Canada. Here, I present a kinematic model of the region that shows how regional strike-slip fault systems, including plate-boundary transform faults, interacted with each other, and with north-striking oroclinal folds and fold-and-thrust belts, which formed progressively during coeval shortening between Eurasia and North America. These Late Cretaceous–early Eocene interactions are manifestations of the plate reorganizations in the Pacific and Atlantic-Arctic regions that took place at that time, and that led to rifting and seafloor spreading within the globe-encircling Eurasian–North American plate and to the formation of transform-dominant North American–Pacific (sensu lato) and possibly North American–Arctic plate boundaries.
Genesis of the Edwards (Balcones Fault Zone) Aquifer
Authors: Schindel Geary M.
Published: October 2019

The San Antonio segment of the Edwards (Balcones Fault Zone) Aquifer of south-central Texas is one of the most important and prolific karst aquifers in the United States. Extending from Kinney County (west) to Hays County (northeast), it is the primary source of water for the municipal and agricultural communities surrounding the greater San Antonio area. Deposited in Early Cretaceous time, rocks of the Edwards Group vary from 150 to 300 m thick and include eight members with highly variable hydraulic attributes and solubility. Its complex tectonic, weathering, and geologic history has allowed dissolution of the highly soluble members to form a highly transmissive karst aquifer. Regionally, the Balcones fault zone provides pathways that allow captured streams to flow into the aquifer in the contributing and recharge zones.

Karstification of the aquifer has occurred by multiple processes, both epigenic and hypogenic, with visual documentation obvious in numerous caves of the area. Currently, overprinting of hypogenic systems by epigenic systems is common. The en echelon down-to-the-south faulting of the Balcones fault zone has resulted in deep burial of the aquifer in the artesian zone, with dissolution at depth driven by numerous processes, including infiltration of chemically aggressive surface water, hydraulic head, mixing corrosion, and biogenic acids. Well production in the artesian zone is commonly limited only by the discharge rate of the pump. The Edwards Aquifer is also noted for its diverse and widespread aquifer-adapted fauna, implying that the aquifer has a well-integrated karst conduit system.
Devils River watershed: Southern Edwards-Trinity Aquifer
Authors: Green R.T. , Fratesi B. , Toll N. , Bertetti F.P. , Nunu R.
Published: October 2019

The Devils River in south-central Texas is recognized as one of the remaining pristine rivers in the state. Adding to its importance, the Devils River is a key tributary to the Rio Grande, providing essential freshwater flows to south Texas and the Rio Grande Valley. An efficient conveyance system for groundwater is shown to have formed in the karst carbonate watershed, located in a semiarid environment with modest distributed recharge, oftentimes less than 1–2 cm/yr. This conveyance system comprises preferential flow pathways that developed coincident with river channels. A strong correlation between wells with high well yield and proximity to higher-order river channels (i.e., within 2.5 km) was used as evidence of the presence of preferential flow pathways. An important observation is that groundwater flow in the Devils River watershed appears to be controlled by the morphology of the area more than the bulk hydraulic properties of the rocks. Flow measurements in the Devils River measured under relatively high- and low-flow conditions support the hypothesis that the river is gaining in downstream reaches. This characteristic leads to perennial river flow being restricted to only the lower reach of the river. Last, essentially all of the recharge to Amistad Reservoir that is derived from the Devils River watershed is contributed as surface flow from the river, and there is minimal underflow or cross-formational flow from the watershed at the point where the watershed abuts Amistad Reservoir.
Water quality and the bad-water (saline-water) zone of the Edwards (Balcones Fault Zone) Aquifer
Authors: Sharp John M. , Smith Brian A.
Published: October 2019

The Edwards aquifers are typically faulted, karstified, and transmissive. Water quality is generally excellent; the hydrochemical facies is mostly a calcium bicarbonate water with total dissolved solids (TDS) <500–1000 mg/L. Exceptions to this result from both natural and anthropogenic factors. In the Edwards Plateau, mixing of the formation water with underlying water from the Trinity aquifers or Permian rocks increases salinity to the west. Along the Balcones fault zone, the southern and eastern borders of the Edwards (Balcones Fault Zone) Aquifer are demarcated by a bad-water line where salinity rises to over 1000 mg/L. Detailed studies show that this line is a band, because salinities in the aquifer are not uniform with depth. The bad-water (or saline-water) zone is relatively stable over time, and six hydrochemical facies were identified, which are created by different combinations of dissolution of evaporite and other minerals, mixing with basinal brines, dedolomitization, and cross-formational flow from underlying formations. Flow in this zone is restricted, the waters are reducing, and recent studies suggest that microbes play important chemical and physical roles. The bad-water zone has sufficient water in storage and sufficient permeability so that desalination could be a future water-source option.