A recursive-faulting model of distributed damage in confined brittle materials

We develop a model of distributed damage in brittle materials deforming in triaxial compression based on the explicit construction of special microstructures obtained by recursive faulting. The model aims to predict the effective or macroscopic behavior of the material from its elastic and fracture properties; and to predict the microstructures underlying the microscopic behavior. The model accounts for the elasticity of the matrix, fault nucleation and the cohesive and frictional behavior of the faults. We analyze the resulting quasistatic boundary value problem and determine the relaxation of the potential energy, which describes the macroscopic material behavior averaged over all possible fine-scale structures. Finally, we present numerical calculations of the dynamic multi-axial compression experiments on sintered aluminum nitride of Chen and Ravichandran [1994. Dynamic compressive behavior of ceramics under lateral confinement. J. Phys. IV 4, 177–182; 1996a. Static and dynamic compressive behavior of aluminum nitride under moderate confinement. J. Am. Soc. Ceramics 79(3), 579–584; 1996b. An experimental technique for imposing dynamic multiaxial compression with mechanical confinement. Exp. Mech. 36(2), 155–158; 2000. Failure mode transition in ceramics under dynamic multiaxial compression. Int. J. Fracture 101, 141–159]. The model correctly predicts the general trends regarding the observed damage patterns; and the brittle-to-ductile transition resulting under increasing confinement

Evolution of the fine-structure constant in runaway dilaton models

We study the detailed evolution of the fine-structure constant $\alpha$ in the string-inspired runaway dilaton class of models of Damour, Piazza and Veneziano. We provide constraints on this scenario using the most recent $\alpha$ measurements and discuss ways to distinguish it from alternative models for varying $\alpha$. For model parameters which saturate bounds from current observations, the redshift drift signal can differ considerably from that of the canonical $\Lambda$CDM paradigm at high redshifts. Measurements of this signal by the forthcoming European Extremely Large Telescope (E-ELT), together with more sensitive $\alpha$ measurements, will thus dramatically constrain these scenarios.Comment: 11 pages, 4 figure

Trends and transitions observed in an iconic recreational fishery across 140 years

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordRecreational fishing has taken place for centuries and is a globally popular activity, yet a lack of monitoring data means historical trends in recreational fisheries are often little understood compared to their commercial counterparts. We examined archival sources and conducted fisher interviews to examine changes in the Queensland recreational snapper (Chrysophrys auratus) fishery throughout its documented history. Over a 140-year period, we extracted data on technological innovations, catch rate trends, and social and regulatory change. Technological innovations were evident throughout the history of the recreational fishery. During the 1960s, 1990s and 2000s, several periods of rapid technological transition occurred, where a technology was adopted by >50% of recreational fishers within 10 years of its introduction. Since the 1960s, the timing and rate of adoption of fish-finding technology by recreational fishers has kept pace with the commercial sector. These technological advances have profoundly increased recreational targeting ability, but despite these advances, recalled recreational catch rate trends demonstrated significant declines over the course of the 20th century. While minimum size limits have been imposed on the snapper fishery for over a century, in contrast, the introduction of recreational in-possession limits only commenced in the 1990s. At this time, the beginnings of a societal transition was also observed, where longstanding ‘take all’ attitudes towards fishing began to be replaced by a more conservation minded ethic. This shift was driven in part by the changing regulatory landscape, as well as wider attitudinal change influenced by the media and shifting societal norms, although whether this led to a reduction in total recreational catch remains unclear due to a lack of fishery-wide monitoring data and the open access nature of the recreational fishery. This study demonstrates that in the absence of systematic data collection, archival sources and fisher interviews can contribute an interdisciplinary knowledge base for understanding and interpreting historical fishery trends.RT, SB and JP were supported by the ARC Centre of Excellence for Coral Reef Studies. Fieldwork costs were supported by the University of Queensland’s New Staff Start-Up Fund, awarded to RT, and the Fisheries Research Development Corporation (FRDC) on behalf of the Australian Government, report 2013-018 "Using commercial and recreational fisher knowledge to reconstruct historical catch rates for Queensland pink snapper (Pagrus auratus) and Spanish mackerel (Scomberomorus commerson): long-term data for incorporation into future stock assessments”

Intravital imaging reveals p53-dependent cancer cell death induced by phototherapy via calcium signaling.

One challenge in biology is signal transduction monitoring in a physiological context. Intravital imaging techniques are revolutionizing our understanding of tumor and host cell behaviors in the tumor environment. However, these deep tissue imaging techniques have not yet been adopted to investigate the second messenger calcium (Ca2+). In the present study, we established conditions that allow the in vivo detection of Ca2+ signaling in three-dimensional tumor masses in mouse models. By combining intravital imaging and a skinfold chamber technique, we determined the ability of photodynamic cancer therapy to induce an increase in intracellular Ca2+ concentrations and, consequently, an increase in cell death in a p53-dependent pathway

Effects Of Climate, Land Use And In-Stream Habitat On Appalachian Elktoe (Alasmidonta Raveneliana) In The Nolichucky River Drainage, North Carolina

The Appalachian elktoe (Alasmidonta raveneliana) is endemic to the Blue Ridge Physiographical Province in western North Carolina and eastern Tennessee. Populations are small and geographically isolated in the headwaters of 10 streams in western North Carolina. Appalachian elktoe populations face a range of threats including climate and land use change, population fragmentation and modification of in-stream habitat. I examined long term (1970-2009) water chemistry and temperature data obtained for 19 streams that historically supported Appalachian elktoe populations. Streams were grouped into two categories: those with apparently stable populations and those with extirpated or severely declining populations. I found that streams with stable Appalachian elktoe populations were cooler with higher dissolved oxygen and lower specific conductance levels compared to streams with declining or extirpated populations. Next, in 2015, I surveyed Appalachian elktoe populations across the Nolichucky drainage at 25 sites and quantified in-stream habitat variables. I used USGS land use data for 1992 and 2011 for all sites. Land use in all streams was predominantly forest with some catchments having >90% forest in both 1992 and 2011. I found that streams with suitable Appalachian elktoe habitat have significantly more forest cover and less disturbance than streams with declining or extirpated populations

Ophiolite-bearing Vermoshi Flysch (Albanian Alps, Northern Albania): elements for its correlation in the frame of Dinaric-Hellenic Belt

The tectonic setting of the Albanian Alps, Northern Albania, is characterized by a thick pile of tectonic units whose uppermost structural level is represented by the Vermoshi Unit, cropping out just few km north of the Shkoder-Péc Line. This unit includes a single formation, the Vermoshi Flysch, characterized by turbidite deposits consisting of arenites, shales and marls. The Vermoshi Flysch has been sampled for paleontological datings and petrographical analyses of the arenite beds along five selected and well exposed sections in the Vermoshi Valley. The nannoplancton and forams associations detected in the analyzed samples point out to a Barremian age, whereas the petrographical modal analysis of arenites indicates that all the samples have a mixed/hybrid silicilastic-carbonate composition, ranging from quartz-rich sublitharenites to quartz-poor litharenites. However, the main feature ot these arenites is the occurrence of fragments derived from an ophiolite sequence. The petrographical data suggest that these deposits can be regarded as supplied by two different source areas, represented by the margins of the basin where the Vermoshi Flysch was deposited. Whereas one of the border was represented by the Adria continental margin, the opposite one was characterized by an advancing nappe, constituted by ophiolites and their sedimentary cover. In this frame, the Vermoshi Flysch can be regarded as the southernmost part of the Vranduk Flysch, cropping out in Serbia and Croatia. This type of deposits, widespread in the Dinaric-Hellenic belt, can be considered as the sedimentary marker of the Late Jurassic - Early Cretaceous tectonic phases related to the closure of the oceanic area present between the Adria and the Eurasia plate