Simultaneous existence of two spin-wave modes in ultrathin Fe/GaAs(001) films studied by Brillouin Light Scattering: experiment and theory

A double-peaked structure was observed in the {\it in-situ} Brillouin Light Scattering (BLS) spectra of a 6 \AA$$ thick epitaxial Fe/GaAs(001) film for values of an external magnetic field $H$, applied along the hard in plane direction, lower than a critical value $H_c\simeq 0.9$ kOe. This experimental finding is theoretically interpreted in terms of a model which assumes a non-homogeneous magnetic ground state characterized by the presence of perperpendicular up/down stripe domains. For such a ground state, two spin-wave modes, namely an acoustic and an optic mode, can exist. Upon increasing the field the magnetization tilts in the film plane, and for $H \ge H_{c}$ the ground state is homogeneous, thus allowing the existence of just a single spin-wave mode. The frequencies of the two spin-wave modes were calculated and successfully compared with the experimental data. The field dependence of the intensities of the corresponding two peaks that are present in the BLS spectra was also estimated, providing further support to the above-mentioned interpretation.Comment: Shortened version (7 pages). Accepted for publication in Physical Review

Brillouin scattering studies in Fe3_3O4_4 across the Verwey transition

Brillouin scattering studies have been carried out on high quality single crystals of Fe$_3$O$_4$ with [100] and [110] faces in the temperature range of 300 to 30 K. The room temperature spectrum shows a surface Rayleigh wave (SRW) mode at 8 GHz and a longitudinal acoustic (LA) mode at 60 GHz. The SRW mode frequency shows a minimum at the Verwey transition temperature $T_V$ of 123 K. The softening of the SRW mode frequency from about 250 K to $T_V$ can be quantitatively understood as a result of a decrease in the shear elastic constant C$_{44}$, arising from the coupling of shear strain to charge fluctuations. On the other hand, the LA mode frequency does not show any significant change around $T_V$, but shows a large change in its intensity. The latter shows a maximum at around 120 K in the cooling run and at 165 K in the heating run, exhibiting a large hysteresis of 45 K. This significant change in intensity may be related to the presence of stress-induced ordering of Fe$^{3+}$ and Fe$^{2+}$ at the octahedral sites, as well as to stress-induced domain wall motion.Comment: 14 pages, 3 figures, accepted in Physical Review B 200

Effects of antiplatelet therapy after stroke due to intracerebral haemorrhage (RESTART): a randomised, open-label trial

Antiplatelet therapy reduces the risk of major vascular events for people with occlusive vascular disease, although it might increase the risk of intracranial haemorrhage. Patients surviving the commonest subtype of intracranial haemorrhage, intracerebral haemorrhage, are at risk of both haemorrhagic and occlusive vascular events, but whether antiplatelet therapy can be used safely is unclear. We aimed to estimate the relative and absolute effects of antiplatelet therapy on recurrent intracerebral haemorrhage and whether this risk might exceed any reduction of occlusive vascular events

Why do earlier-arriving migratory birds have better breeding success?

In migratory birds, early arrival on breeding sites has been widely associated with greater breeding success, but the mechanisms driving these benefits are rarely known. Acquisition of higher quality territories or carry-over effects of better non-breeding season conditions are frequently cited as possible mechanisms through which early-arrivers can achieve greater reproductive output. However, benefits of early arrival could also result from increased time available for breeding, independent of variation in territory quality and associated fitness. Increased time available for breeding among early arrivers could directly influence reproductive success through the time available for replacement clutches following nest loss. However, the benefits of replacement clutches may also depend on seasonal variation in nest survival, and the consequences for juvenile recruitment of hatching at different times in the season. Here we construct a simulation model to explore the potential for time-constrained capacity for replacement clutches to drive relationships between timing of arrival and reproductive success in avian migratory systems, and the influence of seasonal variation in both nest survival and subsequent offspring recruitment probability on these relationships. We show that positive relationships between arrival timing and reproductive success can arise solely through the greater time capacity for replacement clutches among early-arrivers, even when juvenile recruitment declines seasonally and thus later re-nesting attempts contribute fewer recruits to the population. However, these relationships vary depending on the seasonal pattern of nest survival. The benefits of early arrival are greatest when nest survival rates are constant or decline seasonally, and early arrival is least beneficial when nest success rates increase over the breeding season, although re-nesting capacity can mitigate this effect. The time benefits of early arrival facilitating replacement clutches following nest loss may therefore be an important source of selection on migratory timings, and empirical measures of seasonal variation in nest survival, re-nesting and juvenile recruitment rates are needed in order to identify the costs and benefits associated with individual migration phenology and the selection pressures influencing migratory timings

Length of carotid stenosis predicts peri-procedural stroke or death and restenosis in patients randomized to endovascular treatment or endarterectomy.

BACKGROUND: The anatomy of carotid stenosis may influence the outcome of endovascular treatment or carotid endarterectomy. Whether anatomy favors one treatment over the other in terms of safety or efficacy has not been investigated in randomized trials. METHODS: In 414 patients with mostly symptomatic carotid stenosis randomized to endovascular treatment (angioplasty or stenting; n = 213) or carotid endarterectomy (n = 211) in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS), the degree and length of stenosis and plaque surface irregularity were assessed on baseline intraarterial angiography. Outcome measures were stroke or death occurring between randomization and 30 days after treatment, and ipsilateral stroke and restenosis ≥50% during follow-up. RESULTS: Carotid stenosis longer than 0.65 times the common carotid artery diameter was associated with increased risk of peri-procedural stroke or death after both endovascular treatment [odds ratio 2.79 (1.17-6.65), P = 0.02] and carotid endarterectomy [2.43 (1.03-5.73), P = 0.04], and with increased long-term risk of restenosis in endovascular treatment [hazard ratio 1.68 (1.12-2.53), P = 0.01]. The excess in restenosis after endovascular treatment compared with carotid endarterectomy was significantly greater in patients with long stenosis than with short stenosis at baseline (interaction P = 0.003). Results remained significant after multivariate adjustment. No associations were found for degree of stenosis and plaque surface. CONCLUSIONS: Increasing stenosis length is an independent risk factor for peri-procedural stroke or death in endovascular treatment and carotid endarterectomy, without favoring one treatment over the other. However, the excess restenosis rate after endovascular treatment compared with carotid endarterectomy increases with longer stenosis at baseline. Stenosis length merits further investigation in carotid revascularisation trials

Mechanisms of Degradation and Identification of Connectivity and Erosion Hotspots

The context of processes and characteristics of soil erosion and land degradation in Mediterranean lands is outlined. The concept of connectivity is explained. The remainder of the chapter demonstrates development of methods of mapping, analysis and modelling of connectivity to produce a spatial framework for development of strategies of use of vegetation to reduce soil erosion and land degradation. The approach is applied in a range of typical land use types and at a hierarchy of scale from land unit to catchment. Patterns of connectivity and factors influencing the location and intensity of processes are identified, including the influence of topography, structures such as agricultural terraces and check dams, and past land uses. Functioning of connectivity pathways in various rainstorms is assessed. Modes of terrace construction and extent of maintenance, as well as presence of tracks and steep gradients are found to be of importance. A method of connectivity modelling that incorporates effects of structure and vegetation was developed and has been widely applied subsequently

Effect of X-Ray Attenuation of Arterial Obstructions on Intravenous Thrombolysis and Outcome after Ischemic Stroke

<div><p>Objective</p><p>To assess whether the x-ray attenuation of intra-arterial obstruction measured on non-contrast CT in ischemic stroke can predict response to thrombolysis and subsequent functional outcome.</p><p>Methods</p><p>The Third International Stroke Trial (IST-3) was a multicenter randomized-controlled trial of intravenous thrombolysis (rt-PA) given within six hours of ischemic stroke. Ethical approval and informed consent were obtained. In a subgroup of 109 IST-3 patients (38 men, median age 82 years), a single reader, masked to all clinical and other imaging data, manually measured x-ray attenuation (Hounsfield Units, HU) on non-contrast CT at the location of angiographically-proven intra-arterial obstructions, pre-randomization and at 24–48 hour follow-up. We calculated change in attenuation between scans. We assessed the impact of pre-randomization arterial obstruction attenuation on six-month functional outcome.</p><p>Results</p><p>Most arterial obstructions (64/109, 59%) were hyperattenuating (mean 51.0 HU). Compared with control, treatment with rt-PA was associated with a greater, but non-significant, reduction in obstruction attenuation at follow-up (-8.0 HU versus -1.4 HU in patients allocated control, p = 0.117). In multivariable ordinal regression analysis controlled for patient age, stroke severity, location and extent of obstruction, time from stroke onset to baseline scan and rt-PA treatment allocation, the attenuation of pre-randomization arterial obstruction was not independently associated with six-month outcome (odds ratio = 0.99, 95% confidence interval = 0.94–1.03, p = 0.516).</p><p>Conclusions</p><p>In ischemic stroke, the x-ray attenuation of the arterial obstruction may decline more rapidly from baseline to 24–48 hours following treatment with thrombolysis but we found no evidence that baseline arterial obstruction attenuation predicts six-month outcome.</p></div

Biographical Narratives of Encounter: The Significance of Mobility and Emplacement in Shaping Attitudes towards Difference

This paper is located within work in urban studies about the significance of contact with difference as a means for reducing prejudice and achieving social change. Recent approaches, influenced by theories of affect, have emphasised non-conscious everyday negotiations of difference in the city. In this paper it is argued that such approaches lose sight of the significance of the subject: of the reflective judgements of ‘others’ made by individuals; of our ability to make decisions around the control of our feelings and identifications; and of the significance of personal pasts and collective histories in shaping the ways we perceive and react to encounters. Rather, this paper uses a biographical approach focusing on interviewees’ narratives of encounter. Through its attention to processes of mobility and emplacement, it contributes to debates about when contact with difference matters by highlighting the importance of everyday social normativities in the production of moral dispositions

High-performance versatile setup for simultaneous Brillouin-Raman micro-spectroscopy

This is the author accepted manuscript. The final version is available from American Physical Society via the DOI in this record.Brillouin and Raman scattering spectroscopy are established techniques for the nondestructive contactless and label-free readout of mechanical, chemical and structural properties of condensed matter. Brillouin-Raman investigations currently require separate measurements and a site-matched approach to obtain complementary information from a sample. Here we demonstrate a new concept of fully scanning multimodal micro-spectroscopy for simultaneous detection of Brillouin and Raman light scattering in an exceptionally wide spectral range, from fractions of GHz to hundreds of THz. It yields an unprecedented 150 dB contrast, which is especially important for the analysis of opaque or turbid media such as biomedical samples, and spatial resolution on a sub-cellular scale. We report the first applications of this new multimodal method to a range of systems, from a single cell to the fast reaction kinetics of a curing process, and the mechano-chemical mapping of highly scattering biological samples.S. Corezzi acknowledges financial support from MIUR-PRIN (Project No. 2012J8X57P). S. Caponi acknowledges support from PAT (Provincia Autonoma di Trento) (GP/PAT/2012) “Grandi Progetti 2012” Project “MaDEleNA.” P. S., A. M., M. P. acknowledge financial support from Centro Nazionale Trapianti (Project: “Studio di cellule per uso clinico umano, con particolare riferimento a modelli cellulari (liposomi) e linee cellulari in interazione con crioconservanti e con materiali biocompatibili”). L. C. and S. Caponi acknowledge financial support from Consiglio Nazionale delle Ricerche-Istituto Officina dei Materiali. F. P. acnowledges support from the UK Engineering and Physical Sciences Research Council (Grant No. EP/M028739/1 (F. P.)). The authors acknowledge Jacopo Scarponi for valuable help in setting up the hardware and software system for simultaneous Raman and BLS measurements

Postsecular planning? The idea of municipal spirituality

© 2015 Taylor & Francis. In the contemporary political context, religion is rarely out of the news, usually postulated as a regressive force, battling against modern liberal Western values. However, in everyday life, and specifically with regard to place value, the situation is more complex. This paper addresses the challenge this context and the attendant notion of postsecularism bring to planning practice. It argues that religious and spiritual values can be rearticulated as concepts which add a substantive positive dimension to planning and its conceptualisation and constructions of place. This is done by developing the notion of municipal spirituality, which draws on the theological conceptions of transcendence and the common good to redefine the value of places whose worth cannot easily be made in instrumental terms. In so doing, it challenges the current antagonistic opposition of religious and liberal democratic values, repositioning religious and spiritual concepts in an inclusive way. The idea of municipal spirituality illustrates how planning could have a role in defending and promoting such places. Further, it demonstrates the importance of engaging in agonistic rather than antagonistic debate, rearticulating the criteria on which places can be valued by planning practice