Dual Fronts Research Articles

Tectonic evolution of the South Tazin Lake shear zone; a major Arrowsmith-age (ca. 2.36 Ga) structure in the SW Rae craton, Laurentia

The Rae Province records the effects of multiple, staggered orogenies along both margins, leaving a complex record of tectonism within major crustal-scale shear zones. While the recently recognized 2.5–2.3 Ga Arrowsmith orogeny is now known to have affected a large tract of the western Rae, few related structures have been described. In this paper, we present the first detailed investigation of such a structure, the ‘South Tazin Lake shear zone’, localized along the Nolan-Zemlak lithotectonic domain boundary in the SW Rae. Multi-scale structural analysis undertaken herein documents the lithostructural zonation and strain progression across this structure and evaluates its context in the regional tectonic evolution. Strain intensity increases dramatically from north to south, with onset of thick, continuous intervals of protomylonite to ultramylonite toward and into a 3–5 km wide corridor that straddles the Nolan-Zemlak domain boundary and constitutes the core of the shear zone. New U-Pb zircon igneous crystallization ages are consistent with previous results for units across the Nolan-Zemlak domain boundary while 40Ar-39Ar thermochronology of hornblende and biotite provides temporal constraints on deformation and a more detailed thermal evolution than previous studies. An 40Ar-39Ar date of 2361 ± 12 Ma for hornblende overgrowing the sheared and recrystallized matrix in blastomylonitic rocks places a minimum age on D2 mylonitization. This, together with similar ages in the core of the shear zone from foliation-parallel hornblende, definitively links ductile shearing and the related S2 fabric along the South Tazin Lake shear zone with Arrowsmith orogenesis. Cooling rates suggest an initial accelerated phase (∼2360–2350 Ma) of post-Arrowsmith exhumation, but the absence of extensional shear-sense indicators implies control by structures outside of the immediate area; or masking by younger (Taltson-age) structures. This was likely followed by a much slower erosion-related (≤2.35 Ga) phase. All-told, the South Tazin Lake shear zone represents a significant Arrowsmith-age tectonic front that was reactivated only along its southern margin under ductile–brittle conditions during the ca. 1.93 Ga Taltson orogeny. These dual fronts were later transposed to the northeast in concert with deformation along the Black Bay fault during the ca. 1.90 Ga Snowbird orogeny.

Progression of flood risk assessment in India at a decadal scale: a critical review

Abstract Floods are a recurrent natural phenomenon in India, including perennial occurrences in some parts of the country. Progressively, floods are transformed into flood hazards because of the anthropogenic activities in the flood plains and adjoining catchments, causing injuries, loss of lives, and property damage. Flood hazards, when considered in relation to vulnerability and exposure limits, describe the associated flood risk. This article aims to discuss the progression in flood risk assessment through several government policies and actions in India at a decadal scale from 1951 to 2020. While doing this, some important extreme flood events witnessed in those decades that shaped the perspectives, measures, action plans, and policies in the subsequent years are discussed. The review confirms that with the changing patterns of floods, associated hazards, and risks over the years, improvements in risk assessment approaches are noticeable on dual fronts. Technical advancements in flood risk assessment have corroborated the policy reforms. Albeit these developments, the issues related to the scale of study, data sources and resolutions, climatic variability, urban development, complex population dynamics, and their interrelationships in the context of flood risk need to be resolved with serious efforts. Addressing these issues through multidimensional strategies is imperative to aver robust flood risk assessment.

An ANN-based advancing double-front method for automatic isotropic triangle generation

The advancing front method (AFM) is one of the widely used unstructured grid generation techniques. However, the efficiency is relatively low because only one cell is generated in the advancing procedure. In this work, a novel automatic isotropic triangle generation technique is developed by introducing an artificial neural network (ANN) based advancing double-front method (ADFM) to improve the mesh generation efficiency. First, a variety of different patterns are extracted from the AFM mesh generation method and extended to the ADFM method. The mesh generation process in each pattern is discussed in detail. Second, an initial isotropic triangular mesh is generated by the traditional mesh generation method, and then an approach for automatic extraction of the training dataset is proposed. The preprocessed dataset is input into the ANN to train the network, then some typical patterns are obtained through learning. Third, after inputting the initial discrete boundary as initial fronts, the grid is generated from the shortest front and adjacent front. The coordinates of the points contained in the dual fronts and the adjacent points are sent into the neural network as the grid generation environment to obtain the most possible mesh generation pattern, the corresponding methods are used to update the advancing front until the whole computational domain is covered by initial grids, and finally, some smoothing techniques are carried out to improve the quality initial grids. Several typical cases are tested to validate the effectiveness. The experimental results show that the ANN can accurately identify mesh generation patterns, and the mesh generation efficiency is 50% higher than that of the traditional single-front AFM.

The Produced Water Conundrum Grows Across Unconventionals

Shale players have a love-hate relationship with water. It’s an essential ally going into downhole to help proliferate fractures in the subsurface and free up stuck hydrocarbons. It’s a parasite coming out - a briny byproduct that can easily outpace oil production from any given well. Likewise, operators must deal with water management on dual fronts. The first is sourcing the water to be used in the fracturing of the well. Second is finding the right solution for the flowback and formation water coming out of the well. Early on, the answer for the former was freshwater sources. However, once the strain set in from general scarcity, drought, environmental concerns or the like, industry started looking hard at the recycle and reuse of produced water - a solution where the problem becomes the answer. Water recycling rates vary widely between unconventional basins. For the domestic oil industry, data provider IHS Markit forecast in an April 2020 report the vast majority of wastewater leaving an oil field in 2022 will still not be recycled. It will instead be injected into disposal wells, which is currently the most common practice for produced water management. This option is costly and risky, especially for wells that are located some distance from the nearest disposal well. It has also come under increased scrutiny because of the potential effects of disposal well use on the surrounding area’s seismic activity. “Going back to the beginning of unconventional resource production, the focus was understandably on the water needed for drilling and completions,” Paola Perez-Pena, a principal researcher at IHS Markit, commented in an analysis. “Now that there is a considerable, established production, operators are realizing the extent to which produced water is not only a sizable matter, but an ongoing and essentially, perpetual one.” Produced water is a mix of the water pumped down the well to assist with fracturing plus residual drilling fluid and formation water. On average, with every barrel of oil produced in the US, more than 4 bbl of wastewater is produced, though that number varies from basin to basin. “With water, what you find is producers consider a number of different piping configurations, storage, and disposal well options, as well as reuse opportunities,” said John Walsh, principal technologist for Worley Advisian and author of the book, Produced Water. “There’s no one single strategy or approach that’s going to solve the water problem. There is no silver bullet.” According to an industry brief by Raymond James in July 2019, pre-pandemic US oilfield water production was already a whopping 50 million BWPD. For scale, this amount of water could cover more than 8,000 football fields with a foot of water, every day. The investment bank estimated just under half of the total produced water came from horizontal basins, despite making up close to 80% of onshore crude production. The report forecast that the total volume of produced water from major oil basins in the US could grow to more than 60 million BWPD by 2030 (Fig. 1).

Effects of Dual Fronts on the Spatial Pattern of Chlorophyll-a Concentrations in and off the Changjiang River Estuary

Estuarine fronts have significant effects on estuarine circulation, water quality, and productivity. However, there are limited studies on the joint ecological effects of sediment and plume fronts caused by tidal mixing and a low-salinity plume in and off the Changjiang River Estuary (CRE). Based on observational data during the summers of 1988–2016, we analyzed the spatial correlations between environmental factors and chlorophyll-a (Chl-a) concentrations along the two frontal boundaries. The water mass that is shoreward of the sediment front was characterized by the highest nutrients and total suspended matter (TSM); extensive light limitation caused by TSM consequently led to the lowest Chl-a. The water mass between the sediment and plume fronts displayed the highest Chl-a, which benefited from increased light availability due to rapid deposition of TSM across the sediment front and higher nutrients contributed by the plume and coastal upwelling. Shelf water mass beyond the plume front showed the lowest TSM and nutrients; the distinct reduction of nutrient supply resulted in a relatively low Chl-a. The spatial pattern of summer phytoplankton biomass tended to be a result of the balance of light and nutrients constructed by the two fronts and coastal upwelling in and off the CRE.

“Beginning of the Murmur”: Archival Pre-Texts and Other Sources ed. by Conor Carville, Mark Nixon

and owner of his works. Here Call situates the battles with pirates and plagiarists in the complex context of seventeenth-century publishing practices, resisting the anachronistic temptation to see Molière as a precursor to modern authorship. Quarrels, and especially those surrounding L’école des femmes, provide the basis for the third chapter, which shows why the 1662 comedy posed a serious threat to its contemporaries by combining popular success with the generic innovation of a new “grande comédie” that only Molière could create:“Molière redefined the very nature of successful comedy on the dual fronts of performance and publication, establishing in the process a trademark style which was branded with his individuating ownership” (140). The fourth chapter looks in depth at the year 1666, during which a collection of Molière’s works was published without his consent; meanwhile, Le misanthrope staged the drama of Célimène’s promiscuously circulating letters, which served as an example of the dangers of authorship: both the action of the comedy and the publication history of the year of its premiere show how easily texts can escape their authors. The following chapter tracks the publishing history of the late 1660s and early 1670s.With Le Tartuffe and Le bourgeois gentilhomme, Molière continued to establish himself as author and owner of plays that made money both onstage and in print.A privilege that he was able to obtain in 1671, against the wishes of the Communauté des libraires et imprimeurs, marks a newly-aggressive approach to authorial control, such that “Molière had gone from being an author printed malgré lui to wresting almost complete control of his works from a system designed without an author’s rights in mind” (205). Call argues that the 1672 publication of Les femmes savantes marks the culmination of Molière’s innovation and independence in the world of print. The last chapter explores the fascinating case of Psyché, the result of collaborative writing by Molière, Corneille, and Quinault, staged to the music of Lully, the choreography of Beauchamp, and the machines of the Vigarani family. In spite of playing a relatively minor role in the machine play’s authorship, Molière nonetheless strove to be recognized as its sole author. An afterword examines the 1682 edition of Molière’s complete works, “a remarkably complex effort by the playwright’s contemporaries to reconcile the many competing aspects of Molière’s authorship” (230). University of Iowa Roland Racevskis Carville, Conor, and Mark Nixon, eds. “Beginning of the Murmur”: Archival PreTexts and Other Sources. Amsterdam: Rodopi, 2015. ISBN 978-90-043-0991-3. Pp. 244. While many of the past few years’ editions of Samuel Beckett Today/Aujourd’hui have demonstrated the rich variety of contemporary critical approaches to Beckett’s work, the newest edition makes this diversity of ways of engaging Beckett’s lasting achievement its guiding statement of purpose. Largely comprised of essays developed 218 FRENCH REVIEW 91.1 Reviews 219 from a conference held to celebrate the twenty-fifth anniversary of the Beckett International Foundation at the University of Reading, the volume stands as a testament to, as Conor Carville writes in his introduction, the fact that no one interpretive method or critical school holds the key to unlocking the meanings of Beckett’s work, but that “today there is instead a sense of several very productive strands of research coexisting with and complementing each other” (9). This proliferation of approaches in today’s scholarly community, Carville elegantly argues, is perfectly suited to Beckett’s art, as that art itself emerged from a modernist strand of “experimental cultural practice”(10).Which is to say that Beckett’s art asks a multitude of questions about the world from a variety of perspectives, and today’s brightest and most challenging readers of Beckett’s work continue to follow suit. The present volume’s own proliferation of critical approaches includes, among essays that are unanimously compelling and successful, queer theory, trauma studies, and translation studies (to name only a few), all performed with the most rigorous and exacting kind of close reading. Notable standouts include analyses of Beckett’s literary practice within...

Reconstructing changes in the genotype, phenotype, and climatic niche of an introduced species

An introduced species must contend with enormous environmental variation in its introduced range. In this study, we use niche models and ordination analyses to reconstruct changes in genotype, phenotype, and climatic niche of Johnsongrass Sorghum halepense, which is regarded as one of the world's most threatening invasive plants. In the United States, Johnsongrass has rapidly evolved within‐ and among‐population genetic diversity; our results show that genetic differentiation in expanding Johnsongrass populations has resulted in phenotypic variation that is consistent with habitat and climatic variation encountered during its expansion. Moreover, Johnsongrass expanded from agricultural to non‐agricultural habitat, and now, despite occupying overlapping ranges, extant agricultural and non‐agricultural populations are genetically and phenotypically distinct and manifest different plastic responses when encountering environmental variation. Non‐agricultural accessions are broadly distributed in climatic and geographic space and their fitness traits demonstrate plastic responses to common garden conditions that are consistent with local specialization. In contrast, agricultural accessions demonstrate ‘general purpose’ plastic responses and have more restricted climatic niches and geographic distributions. They also grow much larger than non‐agricultural accessions. If these differences are adaptive, our results suggest that adaptation to local habitat variation plays a crucial role in the ecology of this invader. Further, its success relates to its ability to succeed on dual fronts, by responding simultaneously to habitat and climate variability and by capitalizing on differential responses to these factors during its range expansion.

Dual fronts poised to transform melanoma therapy

With recent successes of immunotherapies and targeted drugs, melanoma has become one of the most dynamic areas of anticancer drug development.

Dynamic behavior of splitting flames in a heated channel

Flame-propagation dynamics with dual peaks in a heated microchannel is predicted by employing a thermal-diffusive model taking into account two reactants. After auto-ignition, the flame immediately splits into two reaction fronts with different luminosities. One front propagates upstream, whereas the other moves downstream, and finally they both extinguish. After some delay, the process is repeated, and reignition of the fuel-air mixture is induced by hot walls. It is also shown that the commonly used infinitely thin reaction zone model, which has no reactant concentration dependence, is not capable of capturing this phenomenon. The splitting flame dynamics with dual fronts is confirmed by photographs taken with a high-speed digital video camera in experimental investigations with a propane-air mixture. The experiments reveal interesting details, namely, coexistence of triple reaction peaks during the process of propagation of splitting flames is observed, and the flame splitting phenomenon occurs twice in one extinction-ignition period.

Resistance Revisited: Looking Back at 10 Years of Multidrug Resistance Research

A New Front Today, those efforts are proceeding on dual fronts. Whereas scientists 10 years ago were concerned only with multidrug resistance against chemotherapy, those working today must also contend with single-drug resistance to newer, targeted therapies such as imatinib (Gleevec), a drug for chronic myelogenous leukemia (CML) and other cancers that inactivates a cancer-inducing protein called Bcr-Abl. Unlike chemotherapy — which kills rapidly dividing cells regardless of whether they’re cancerous — targeted therapies interfere with specifi c molecules involved in cancer and tumor growth. The new era of targeted therapy was supposed to leave chemotherapy behind and multidrug resistance behind with it. That’s because re

Multitherapy Approach to Onychomycosis Therapy

New medications and new formulations have provided an increase in the cure rates for onychomycosis. Many cases of infection, however, are still not cured. It is not always obvious which factors are most relevant to reduction of cure, and factors may vary with each patient. For these reasons, a multitherapy approach to onychomycosis may be needed to individualize treatment to each patient's specific condition. Different presentations and severity levels of onychomycosis may respond differently to treatment modalities and require varying amounts of intervention. Nail débridement may be used to lessen the burden of infection in cases in which drug penetration may not occur adequately otherwise, such as dermatophytoma, onycholysis, or lateral infection. Ciclopirox nail lacquer has been approved for use in conjunction with regular débridement and represents the first approved multitherapy approach. Topical antifungals may be combined with oral antifungals to provide dual fronts of drug penetration. Similarly, two oral medications may be combined to provide a wider spectrum of antifungal activity and differential mode of action against the organisms, which may increase fungistatic or fungicidal action. There is a nonclinical component of therapy, represented by patient education on onychomycosis infection and treatment, which should be used to ensure that patient expectations are realistic and to encourage patient compliance with the chosen regimens.

Dual fronts in a phase field model

We study a dual front behavior observed in a reaction–diffusion system arising initially in the context of phase field models. A precursor front propagates into a stable phase, generating a metastable “intermediate phase”. This intermediate phase then decays via an oscillating front, producing a periodic structure which later coarsens. Unlike previously studied models in which dual fronts appear, the appearance of the split front is controlled not by an interchange of wave speeds, but by the existence of the precursor wave. By means of an expansion in small thermal diffusivity, we argue that this behavior is generic.

A study on the rating of import sources for industrial products in a newly industrializing country: The case of South Korea

This study looks at the purchasing of imported industrial products among managers in a newly industrializing country (NIC). The authors propose that the industrial marketing requirements to buyers in an NIC, given their mix of environmental and organizational conditions, are different from those in advanced nations. South Korea, in addition to being a representative NIC, is interesting from the standpoint that there is a heavy import dependence on Japan. The results of a survey of South Korean companies importing industrial products in key representative industries suggest that the strong ratings for Japanese industrial products are based not only on stronger overall quality, but also on their higher orientation toward intangible factors such as communication, technical assistance, and reliability. Moreover, many of the Japanese sources have “localized” their product to compete with the domestic suppliers as well. These results suggest that in order to improve their performance, other foreign suppliers must compete on dual fronts; a product-related dimension as well as a more service-related dimension. Other possible avenues for improvement can be found by examining differences in supplier ratings based on organizational and situational influences. This study shows that buyers in smaller and newer companies tend to be more open to non-Japanese products. The findings also suggest that certain technology-transfer modes may be more conducive to generating better supplier ratings. Overall, the variability of country ratings across situational factors strongly indicates that more conceptualization and theory building is needed in the international industrial marketing area.

Dual fronts propagating into an unstable state

The interface between an unstable state and a stable state usually develops a single confined front travelling with constant velocity into the unstable state. Recently, the splitting of such an interface into two fronts propagating with different velocities was observed numerically in a magnetic system. The intermediate state is unstable and grows linearly in time. We first establish rigorously the existence of this phenomenon, called a 'dual front', for a class of structurally unstable one-component models. Then we use this insight to explain dual fronts for a generic two-component reaction-diffusion system, and for the magnetic system.