249 research outputs found
The narratives of Hardship: : The new and the old poor in the aftermath of the 2008 crisis in Europe
This document is the Accepted Manuscript version of the following article: Hulya Dagdeviren, Matthew Donoghue, and Lars Meier, âThe narratives of hardship: the new and the old poor in the aftermath of the 2008 crisis in Europeâ, The Sociological Review, vol. 65 (2): 369-385, May 2017. The final, definitive version of record is available online at doi: https://doi.org/10.1111/1467-954X.12403. Published by SAGE.This paper examines poverty and hardship in Europe after the 2008 crisis, using household interviews in nine European countries. A number of findings deserve highlighting. First, making a distinction between âthe old poorâ (those who lived in poverty before as well as after the crisis) and âthe new poorâ (thosewho fell into hardship after the crisis), we show that hardship is experienced quite differently by these groups. Second, the household narratives showed that while material deprivations constitute an important aspect of hardship, the themes of insecurity and dependency also emerged as fundamental dimensions. In contrast to popular political discourse in countries such as the UK, dependency on welfare or family was experienced as a source of distress and manifested as a form of hardship by participants in all countries covered in this study.Peer reviewedFinal Accepted Versio
Low-temperature magnetic properties of pelagic carbonates: Oxidation of biogenic magnetite and identification of magnetosome chains
Pelagic marine carbonates provide important records of pastenvironmental change. We carried out detailed low-temperature magneticmeasurements on biogenic magnetite-bearing sediments from the SouthernOcean (Ocean Drilling Program (ODP) Holes 738B, 738C, 689D, and 690C)and on samples containing whole magnetotactic bacteria cells. Wedocument a range of low-temperature magnetic properties, includingreversible humped low-temperature cycling (LTC) curves. Differentdegrees of magnetite oxidation are considered to be responsible for theobserved variable shapes of LTC curves. A dipole spring mechanism inmagnetosome chains is introduced to explain reversible LTC curves. Thisdipole spring mechanism is proposed to result from the uniaxialanisotropy that originates from the chain arrangement of biogenicmagnetite, similar to published results for uniaxial stable singledomain (SD) particles. The dipole spring mechanism reversibly restoresthe remanence during warming in LTC measurements. This supports aprevious idea that remanence of magnetosome chains is completelyreversible during LTC experiments. We suggest that this magneticfingerprint is a diagnostic indicator for intact magnetosome chains,although the presence of isolated uniaxial stable SD particles andmagnetically interacting particles can complicate this test. Magneticmeasurements through the Eocene section of ODP Hole 738B reveal aninterval with distinct magnetic properties that we interpret tooriginate from less oxidized biogenic magnetite and enrichment of abiogenic hard component. Co-occurrence of these two magneticfingerprints during the late Eocene in the Southern Ocean indicates lessoxic conditions, probably due to increased oceanic primary productivityand organic carbon burial
Combined use of magnetometry and spectroscopy for identifying magnetofossils in sediments
Identification of the mineral remains of magnetotactic bacteria (MTB),known as magnetofossils, is of particular interest because theiroccurrence can be used for environmental and climatic reconstructions.Single-domain magnetite particles, which are biomineralized in the cellbody of MTB, have characteristic properties that can be used to detecttheir fossil remains. Acquisition of anhysteretic and isothermalremanent magnetization (ARM and IRM), first-order reversal curve (FORC)diagrams, and ferromagnetic resonance (FMR) spectra were used to detectthe magnetic mineral inventory in Holocene lake sediments. A comparativeanalysis in terms of the discriminatory power of these methods ispresented. The FORC diagrams contain two distinct features: a sharphorizontal ridge centered on the horizontal axis B-c and a feature withsymmetric spread along the vertical B-b axis. The coercivity spectraderived from the central ridge coincides with that derived from ARM andIRM acquisition curves and is compatible with the presence ofnoninteracting linear chains of single-domain magnetite. The secondfeature on FORC diagrams is indicative of interacting particles inclusters. In the FMR spectra from bulk sediment, two populations areseparated empirically based on the FORC information. An asymmetricsignal is taken to describe the population, which contains single-domainparticles in clusters. Empirical spectral separation of thiscontribution results in FMR spectra that are similar to those of intactMTB, which strongly suggests that a fraction of linear magnetosomechains is present. Combination of FMR and FORC results demonstrates thestrong potential of these methods for identifying magnetofossils, basedon alignment and interaction patterns of magnetic particles
The Vortex State in Geologic Materials: A Micromagnetic Perspective
A wide variety of Earth and planetary materials are very good recorders of paleomagnetic information. However most magnetic grains in these materials are not in the stable single (SD) domain grain size range, but are larger and in non-uniform vortex magnetization states. We provide a detailed account of vortex phenomena in geologic materials by simulating first-order reversal curves (FORCs) via finite-element micromagnetic modeling of magnetite nanoparticles with realistic morphologies. The particles have been reconstructed from focused ion beam nanotomography of magnetite-bearing obsidian, and accommodate single and multiple vortex structures. Single vortex (SV) grains have fingerprints with contributions to both the transient and transient-free zones of FORC diagrams. A fundamental feature of the SV fingerprint is a central ridge, representing a distribution of negative saturation vortex annihilation fields. SV irreversible events at multiple field values along different FORC branches determine the asymmetry in the upper and lower lobes of generic bulk FORC diagrams of natural materials with grains predominantly in the vortex state. Multi vortex (MV) FORC signatures are modeled here for the first time. MV grains contribute mostly to the transient-free zone of a FORC diagram, averaging out to create a broad central peak. The intensity of the central peak is higher than that of the lobes, implying that MV particles are more abundant than SV particles in geologic materials with vortex state fingerprints. The abundance of MV particles, as well as their SD-like properties point to MV grains being the main natural remanent magnetization carriers in geologic materials.European Research Counci
Malleable Curie Temperatures of Natural Titanomagnetites: Occurrences, Modes, and Mechanisms
Abstract Intermediate-composition titanomagnetites have Curie temperatures (Tc) that depend not only on composition but also on thermal history, with increases of 100°C or more in Tc produced by moderate-temperature (300â400°C) annealing in the laboratory or in slow natural cooling and comparable decreases produced by more rapid cooling (âquenchingâ) from higher temperatures. New samples spanning a range of titanomagnetite compositions exhibit reversible changes in Tc comparable to those previously documented for pyroclastic samples from Mt. St. Helens and Novarupta. Additional high- and low-temperature measurements help to shed light on the nanoscale mechanisms responsible for the observed changes in Tc. High-T hysteresis measurements exhibit a peak in high-field slope khf(T) at the Curie temperature, and the peak magnitude decreases as Tc increases with annealing. Sharp changes in low-T magnetic behavior are also strongly affected by prior annealing or quenching, suggesting that these treatments affect the intrasite cation distributions. We have examined the effects of oxidation state and nonstoichiometry on the magnitude of Tc changes produced by quenching/annealing in different atmospheres. Treatments in air generally cause large changes (ÎTc \u3e 100°). In an inert atmosphere, the changes are similar in many samples but strongly diminished in others. When the samples are embedded in a reducing material, ÎTc becomes insignificant. These results strongly suggest that cation vacancies play an essential role in the cation rearrangements responsible for the observed changes in Tc. Some form of octahedral-site chemical clustering or short-range ordering appears to be the best way to explain the large observed changes in Tc
Detection of noninteracting single domain particles using first-order reversal curve diagrams
We present a highly sensitive and accurate method for quantitativedetection and characterization of noninteracting or weakly interactinguniaxial single domain particles (UNISD) in rocks and sediments. Themethod is based on high-resolution measurements of first-order reversalcurves (FORCs). UNISD particles have a unique FORC signature that can beused to isolate their contribution among other magnetic components. Thissignature has a narrow ridge along the H(c) axis of the FORC diagram,called the central ridge, which is proportional to the switching fielddistribution of the particles. Therefore, the central ridge is directlycomparable with other magnetic measurements, such as remanentmagnetization curves, with the advantage of being fully selective to SDparticles, rather than other magnetic components. This selectivity isunmatched by other magnetic unmixing methods, and offers usefulapplications ranging from characterization of SD particles forpaleointensity studies to detecting magnetofossils and ultrafineauthigenically precipitated minerals in sediments
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