On the exponential convergence to a limit of solutions of perturbed linear Volterra equations

We consider a system of perturbed Volterra integro-differential equations for which the solution approaches a nontrivial limit and the difference between the solution and its limit is integrable. Under the condition that the second moment of the kernel is integrable we show that the solution decays exponentially to its limit if and only if the kernel is exponentially integrable and the tail of the perturbation decays exponentially

Footprints preserve terminal Pleistocene hunt? Human-sloth interactions in North America

Predator-prey interactions revealed by vertebrate trace fossils are extremely rare. We present footprint evidence from White Sands National Monument in New Mexico for the association of sloth and human trackways. Geologically, the sloth and human trackways were made contemporaneously, and the sloth trackways show evidence of evasion and defensive behavior when associated with human tracks. Behavioral inferences from these trackways indicate prey selection and suggest that humans were harassing, stalking, and/or hunting the now-extinct giant ground sloth in the terminal Pleistocene

Exceptionally Slow Rise in Differential Reflectivity Spectra of Excitons in GaN: Effect of Excitation-induced Dephasing

Femtosecond pump-probe (PP) differential reflectivity spectroscopy (DRS) and four-wave mixing (FWM) experiments were performed simultaneously to study the initial temporal dynamics of the exciton line-shapes in GaN epilayers. Beats between the A-B excitons were found \textit{only for positive time delay} in both PP and FWM experiments. The rise time at negative time delay for the differential reflection spectra was much slower than the FWM signal or PP differential transmission spectroscopy (DTS) at the exciton resonance. A numerical solution of a six band semiconductor Bloch equation model including nonlinearities at the Hartree-Fock level shows that this slow rise in the DRS results from excitation induced dephasing (EID), that is, the strong density dependence of the dephasing time which changes with the laser excitation energy.Comment: 8 figure

Atomic X-ray Spectroscopy of Accreting Black Holes

Current astrophysical research suggests that the most persistently luminous objects in the Universe are powered by the flow of matter through accretion disks onto black holes. Accretion disk systems are observed to emit copious radiation across the electromagnetic spectrum, each energy band providing access to rather distinct regimes of physical conditions and geometric scale. X-ray emission probes the innermost regions of the accretion disk, where relativistic effects prevail. While this has been known for decades, it also has been acknowledged that inferring physical conditions in the relativistic regime from the behavior of the X-ray continuum is problematic and not satisfactorily constraining. With the discovery in the 1990s of iron X-ray lines bearing signatures of relativistic distortion came the hope that such emission would more firmly constrain models of disk accretion near black holes, as well as provide observational criteria by which to test general relativity in the strong field limit. Here we provide an introduction to this phenomenon. While the presentation is intended to be primarily tutorial in nature, we aim also to acquaint the reader with trends in current research. To achieve these ends, we present the basic applications of general relativity that pertain to X-ray spectroscopic observations of black hole accretion disk systems, focusing on the Schwarzschild and Kerr solutions to the Einstein field equations. To this we add treatments of the fundamental concepts associated with the theoretical and modeling aspects of accretion disks, as well as relevant topics from observational and theoretical X-ray spectroscopy.Comment: 63 pages, 21 figures, Einstein Centennial Review Article, Canadian Journal of Physics, in pres

Grass burning under our feet: Indigenous enterprise development in a political economy of whiteness

In this article we discuss some of our findings from two research projects that explore opportunities for Indigenous enterprise development in remote locations in Northern and Central Australia. Based on a series of focus groups and in-depth interviews with Indigenous community leaders, Traditional Owners, government officials, Land Council officials and other stakeholders, we discuss barriers to economic development faced by Indigenous communities in remote regions. We argue that many of these barriers are the material effects of discursive practices of ‘whiteness’ in the political economy. We discuss the relationships between institutions and Indigenous communities that constitute the Indigenous political economy and argue that these relationships are informed by discursive practices of whiteness and colonial-capitalist relations of power. We conclude by discussing the implications of our findings for management learning and public policy

Interspecies comparisons of brominated flame retardants in relation to foraging ecology and behaviour of gulls frequenting a UK landfill

This study quantifies and compares concentrations and profiles of legacy and alternative (alt-) brominated flame retardants (BFRs) in the eggs of three gull (Laridae) species of international/UK conservation concern – great black-backed gulls (Larus marinus; n = 7), European herring gulls (L. argentatus; n = 16) and lesser black-backed gulls (L. fuscus; n = 11) in relation to their foraging ecology and behaviour in order to investigate potential exposure pathways at a remote landfill in western Scotland, UK. Egg concentrations of sum (∑) polybrominated diphenyl ethers (∑8PBDEs) in all three species exceeded those for most reported avian species using landfill, except for those in North America. Despite relatively high detection frequencies of ∑hexabromocyclododecanes (∑3HBCDDs) (94–100%), concentrations of ∑8PBDEs exceeded ∑3HBCDDs and ∑5alt-BFRs, with ∑8PBDE levels similar in all three species. Egg carbon isotopic (δ13C) values highlighted a greater marine dietary input in great black-backed gulls that was consistent with their higher BDE-47 levels; otherwise, dietary tracers were minimally correlated with measured BFRs. ∑3HBCDD egg concentrations of herring gulls markedly exceeded those reported elsewhere in Europe. Decabromodiphenylethane (DBDPE) was the only alt-BFR detected (6–14% detection rate), in a single egg of each species. The great black-backed gull egg contained the highest concentration of DBDPE measured in biota to date globally and provides strong evidence for its emerging environmental presence as a BDE-209 replacement in UK wildlife. Correlations between δ13C (dietary source) and some measured BFRs in eggs suggest multiple routes of BFR exposure for gulls frequenting landfill through their diet, behaviour, preening, dermal exposure and likely inhalation. The frequent use of landfill by herring gulls and their increased egg BFR burdens suggest that this species may be an important bioindicator of BFR emissions from such sites.</p

Self-help groups challenge health care systems in the US and UK

Purpose: This research considers how self-help groups (SHGs) and self- help organizations (SHOs) contribute to consumerist trends in two different societies: United States and United Kingdom. How do the health care systems and the voluntary sectors affect the kinds of social changes that SHGs/SHOs make? Methodology/approach: A review of research on the role of SHGs/SHOs in contributing to national health social movements in the UK and US was made. Case studies of the UK and the US compare the characteristics of their health care systems and their voluntary sector. Research reviews of two community level self-help groups in each country describe the kinds of social changes they made. Findings: The research review verified that SHGs/SHOs contribute to national level health social movements for patient consumerism. The case studies showed that community level SHGs/SHOs successfully made the same social changes but on a smaller scale as the national movements, and the health care system affects the kinds of community changes made. Research limitations: A limited number of SHGs/SHOs within only two societies were studied. Additional SHGs/SHOs within a variety of societies need to be studied. Originality/value of chapter Community SHGs/SHOs are often trivialized by social scientists as just inward-oriented support groups, but this chapter shows that local groups contribute to patient consumerism and social changes but in ways that depend on the kind of health care system and societal context

Measurement of the cross section for isolated-photon plus jet production in pp collisions at √s=13 TeV using the ATLAS detector

The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb−1. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- algorithm with radius parameter and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon–jet invariant mass and the scattering angle in the photon–jet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements

Improved Oil Recovery in Fluvial Dominated Deltaic Reservoirs of Kansas Near Term

The objective of this project is to address waterflood problems of the type found in Morrow sandstone reservoirs in southwestern Kansas and Cherokee Group reservoirs in southeastern Kansas. Two demonstration sites operated by different independent oil operators are involved in this project. The Stewart Field is located in Finney County, Kansas and is operated by North American Resources Company. The Nelson Lease is located in Allen County, Kansas, in the N.E. Savonburg Field and is operated by James E. Russell Petroleum, Inc. General topics to be addressed are (1) reservoir management and performance evaluation, (2) waterflood optimization, and (3) the demonstration of recovery processes involving off-the-shelf technologies which can be used to enhance waterflood recovery, increase reserves, and reduce the abandonment rate of these reservoir types. In the Stewart Project, the reservoir management portion of the project conducted during Budget Period I involved performance evaluation. This included (1) reservoir characterization and the development of a reservoir database, (2) volumetric analysis to evaluate production performance, (3) reservoir modeling, (4) laboratory work, (5) identification of operational problems, (6) identification of unrecovered mobile oil and estimation of recovery factors, and (7) identification of the most efficient and economical recovery process. To accomplish these objectives the initial budget period was subdivided into three major tasks. The tasks were (1) geological and engineering analysis, (2) laboratory testing, and (3) unitization. Due to the presence of different operators within the field, it was necessary to unitize the field in order to demonstrate a field-wide improved recovery process. This work was completed and the project moved into Budget Period 2. Budget Period 2 objectives consisted of the design, construction, and operation of a field-wide waterflood utilizing state-of-the-art, off-the-shelf technologies in an attempt to optimize secondary oil recovery. To accomplish these objectives the second budget period was subdivided into five major tasks. The tasks were (1) design and construction of a waterflood plant, (2) design and construction of a water injection system, (3) design and construction of tank battery consolidation and gathering system, (4) initiation of waterflood operations and reservoir management, and (5) technology transfer. In the Savonburg Project, the reservoir management portion involves performance evaluation. This work included (1) reservoir characterization and the development of a reservoir database, (2) identification of operational problems, (3) identification of near wellbore problems such as plugging caused from poor water quality, (4) identification of unrecovered mobile oil and estimation of recovery factors, and (5) preliminary identification of the most efficient and economical recovery process i.e., polymer augmented waterflooding or infill drilling (vertical or horizontal wells). To accomplish this work the initial budget period was subdivided into four major tasks. The tasks included (1) geological and engineering analysis, (2) waterplant optimization, (3) wellbore cleanup and pattern changes, and (4) field operations. This work was completed and the project has moved into Budget Period 2. The Budget Period 2 objectives consisted of continual optimization of this mature waterflood in an attempt to optimize secondary and tertiary oil recovery. To accomplish these objectives the second budget period was subdivided into six major tasks. The tasks were (1) waterplant development, (2) profile modification treatments, (3) pattern changes, new wells and wellbore cleanups, (4) reservoir development (polymer flooding), (5) field operations, and (6) technology transfer