Epitaxial Co2Cr0.6Fe0.4Al thin films and magnetic tunneling junctions

Epitaxial thin films of the theoretically predicted half metal Co2Cr0.6Fe0.4Al were deposited by dc magnetron sputtering on different substrates and buffer layers. The samples were characterized by x-ray and electron beam diffraction (RHEED) demonstrating the B2 order of the Heusler compound with only a small partition of disorder on the Co sites. Magnetic tunneling junctions with Co2Cr0.6Fe0.4Al electrode, AlOx barrier and Co counter electrode were prepared. From the Julliere model a spin polarisation of Co2Cr0.6Fe0.4Al of 54% at T=4K is deduced. The relation between the annealing temperature of the Heusler electrodes and the magnitude of the tunneling magnetoresistance effect was investigated and the results are discussed in the framework of morphology and surface order based of in situ STM and RHEED investigations.Comment: accepted by J. Phys. D: Appl. Phy

Koszul binomial edge ideals

It is shown that if the binomial edge ideal of a graph $G$ defines a Koszul algebra, then $G$ must be chordal and claw free. A converse of this statement is proved for a class of chordal and claw free graphs

Brillouin light scattering study of Co2_{2}Cr0.6_{0.6}Fe0.4_{0.4}Al and Co2_{2}FeAl Heusler compounds

The thermal magnonic spectra of Co$_{2}$Cr$_{0.6}$Fe$_{0.4}$Al (CCFA) and Co$_2$FeAl were investigated using Brillouin light scattering spectroscopy (BLS). For CCFA, the exchange constant A (exchange stiffness D) is found to be 0.48 $\mu$erg/cm (203 meV A$^2$), while for Co$_2$FeAl the corresponding values of 1.55 $\mu$erg/cm (370 meV A$^2$) were found. The observed asymmetry in the BLS spectra between the Stokes and anti-Stokes frequencies was assigned to an interplay between the asymmetrical profiles of hybridized Damon-Esbach and perpendicular standing spin-wave modes, combined with the optical sensitivity of the BLS signal to the upper side of the CCFA or Co$_2$FeAl film

For richer or poorer in sickness for wealth: what price consumerism?

Affluence and material goods of varying types are portents of a millennium age consumer culture that encourages the masses to voluntarily participate in the need to buy, buy and buy! This trend to spend creates a purchasing fervour that preoccupies many consumers with the ongoing yearning to shop until they drop. Clever marketing tactics such as enticing smells, catchy jingles, prize-draw entries, lucrative sales, discounts and the recruitment of celebrities to advertise a range of different wares are just some of the ploys adopted by vendors and retailers to maintain the sustainability of this cycle of consumer spending. This scenario promotes what could be perceived as a never-ending desire to procure yet more products and merchandise, which can create social dilemmas such as personal debt due to, for example, impulse buying, excessive spending and unnecessary borrowing. Retailers and manufacturers are driven by a quest to sell so constantly tout their goods to tempt consumers including those with a need for personal and social respect, to take the bait in order to encourage them to keep buying. This, coupled with the rapid advances in technology over recent decades, has made it easier for consumers to shop, order, obtain and pay for their goods from the comfort of an armchair or via handheld devices, and all at a tap of a button. In essence, technology has added to, or even exacerbated, the materialistic consumer trend as witnessed across many global societies today – from the east and the west to the north and the south. But what impact does consumerism have on the well-being of humankind and, in turn, the environment? This chapter adopts a comparative approach to answer this question by exploring the implications of consumerism as a means for broadening the topic’s framework and to contribute to debates regarding consumerism, well-being, social dilemma, sustainability and techno-economics

Existence of global strong solutions to a beam-fluid interaction system

We study an unsteady non linear fluid-structure interaction problem which is a simplified model to describe blood flow through viscoleastic arteries. We consider a Newtonian incompressible two-dimensional flow described by the Navier-Stokes equations set in an unknown domain depending on the displacement of a structure, which itself satisfies a linear viscoelastic beam equation. The fluid and the structure are fully coupled via interface conditions prescribing the continuity of the velocities at the fluid-structure interface and the action-reaction principle. We prove that strong solutions to this problem are global-in-time. We obtain in particular that contact between the viscoleastic wall and the bottom of the fluid cavity does not occur in finite time. To our knowledge, this is the first occurrence of a no-contact result, but also of existence of strong solutions globally in time, in the frame of interactions between a viscous fluid and a deformable structure

The environmental security debate and its significance for climate change

Policymakers, military strategists and academics all increasingly hail climate change as a security issue. This article revisits the (comparatively) long-standing “environmental security debate” and asks what lessons that earlier debate holds for the push towards making climate change a security issue. Two important claims are made. First, the emerging climate security debate is in many ways a re-run of the earlier dispute. It features many of the same proponents and many of the same disagreements. These disagreements concern, amongst other things, the nature of the threat, the referent object of security and the appropriate policy responses. Second, given its many different interpretations, from an environmentalist perspective, securitisation of the climate is not necessarily a positive development

Human Female Genital Tract Infection by the Obligate Intracellular Bacterium Chlamydia trachomatis Elicits Robust Type 2 Immunity

While Chlamydia trachomatis infections are frequently asymptomatic, mechanisms that regulate host response to this intracellular Gram-negative bacterium remain undefined. This investigation thus used peripheral blood mononuclear cells and endometrial tissue from women with or without Chlamydia genital tract infection to better define this response. Initial genome-wide microarray analysis revealed highly elevated expression of matrix metalloproteinase 10 and other molecules characteristic of Type 2 immunity (e.g., fibrosis and wound repair) in Chlamydia-infected tissue. This result was corroborated in flow cytometry and immunohistochemistry studies that showed extant upper genital tract Chlamydia infection was associated with increased co-expression of CD200 receptor and CD206 (markers of alternative macrophage activation) by endometrial macrophages as well as increased expression of GATA-3 (the transcription factor regulating TH2 differentiation) by endometrial CD4+ T cells. Also among women with genital tract Chlamydia infection, peripheral CD3+ CD4+ and CD3+ CD4- cells that proliferated in response to ex vivo stimulation with inactivated chlamydial antigen secreted significantly more interleukin (IL)-4 than tumor necrosis factor, interferon-γ, or IL-17; findings that repeated in T cells isolated from these same women 1 and 4 months after infection had been eradicated. Our results thus newly reveal that genital infection by an obligate intracellular bacterium induces polarization towards Type 2 immunity, including Chlamydia-specific TH2 development. Based on these findings, we now speculate that Type 2 immunity was selected by evolution as the host response to C. trachomatis in the human female genital tract to control infection and minimize immunopathological damage to vital reproductive structures. © 2013 Vicetti Miguel et al

A Kato type Theorem for the inviscid limit of the Navier-Stokes equations with a moving rigid body

The issue of the inviscid limit for the incompressible Navier-Stokes equations when a no-slip condition is prescribed on the boundary is a famous open problem. A result by Tosio Kato says that convergence to the Euler equations holds true in the energy space if and only if the energy dissipation rate of the viscous flow in a boundary layer of width proportional to the viscosity vanishes. Of course, if one considers the motion of a solid body in an incompressible fluid, with a no-slip condition at the interface, the issue of the inviscid limit is as least as difficult. However it is not clear if the additional difficulties linked to the body's dynamic make this issue more difficult or not. In this paper we consider the motion of a rigid body in an incompressible fluid occupying the complementary set in the space and we prove that a Kato type condition implies the convergence of the fluid velocity and of the body velocity as well, what seems to indicate that an answer in the case of a fixed boundary could also bring an answer to the case where there is a moving body in the fluid

Powers of componentwise linear ideals

We give criteria for graded ideals to have the property that all their powers are componentwise linear. Typical examples to which our criteria can be applied include the vertex cover ideals of certain finite graphs

Public attitudes to inequality in water distribution: Insights from preferences for water reallocation from irrigators to Aboriginal Australians

Water allocation regimes that adjudicate between competing uses are in many countries under pressure to adapt to increasing demands, climate‐driven shortages, expectations for equity of access, as well as societal changes in values and priorities. International authorities expound standards for national allocation regimes that include robust processes for addressing the needs of ‘new entrants' and for varying existing entitlements within sustainable limits. The claims of Indigenous peoples to water represents a newly recognised set of rights and interests that will test the ability of allocation regimes to address the global water governance goal of equity. No study has sought to identify public attitudes or willingness to pay for a fairer allocation of water rights between Indigenous and non‐Indigenous people. We surveyed households from the jurisdictions of Australia's Murray‐Darling Basin, a region undergoing a historic government‐led recovery of water, and found that 69.2% of respondents support the principle of reallocating a small amount of water from irrigators to Aboriginal people via the water market. Using contingent valuation, we estimated households are willing to pay A$21.78 in a one‐off levy. The aggregate value calculated for households in the basin's jurisdictions was A$74.5 million, which is almost double a recent government commitment to fund the acquisition of entitlements for Aboriginal nations of this basin. Results varied by state of residency and affinity with environmental groups. An information treatment that presented narrative accounts from Aboriginal people influenced the results. Insights from this study can inform water reallocation processes