Annihilation and Control of Chiral Domain Walls with Magnetic Fields

The control of domain walls is central to nearly all magnetic technologies, particularly for information storage and spintronics. Creative attempts to increase storage density need to overcome volatility due to thermal fluctuations of nanoscopic domains and heating limitations. Topological defects, such as solitons, skyrmions, and merons, may be much less susceptible to fluctuations, owing to topological constraints, while also being controllable with low current densities. Here, we present the first evidence for soliton/soliton and soliton/antisoliton domain walls in the hexagonal chiral magnet Mn1/3NbS2 that respond asymmetrically to magnetic fields and exhibit pair-annihilation. This is important because it suggests the possibility of controlling the occurrence of soliton pairs and the use of small fields or small currents to control nanoscopic magnetic domains. Specifically, our data suggest that either soliton/soliton or soliton/antisoliton pairs can be stabilized by tuning the balance between intrinsic exchange interactions and long-range magnetostatics in restricted geometriesComment: 8 pages, 4 figure

Integrating Literature, Biodiversity Databases, and Citizen-Science to Reconstruct the Checklist of Chondrichthyans in Cyprus (Eastern Mediterranean Sea)

Chondrichthyans are apex predators influencing the trophic web through a top-down process thus their depletion will affect the remaining biota. Notwithstanding that, research on chondrichthyans is sparse or data-limited in several biogeographic areas worldwide, including the Levantine Sea. We revise and update the knowledge of chondrichthyans in Cyprus based on a bibliographic review that gains information retrieved from peer-reviewed and grey literature, Global Biodiversity Information Facility (135 records of at least 18 species) and the Ocean Biodiversity Information System (65 records of at least14 species), and the citizen science project Mediterranean Elasmobranchs Citizen Observations (117 records per 23 species). Our updated checklist reports 60 species that account for about 70% of the Mediterranean chondrichthyan biota. The list includes 15 more species than the previous checklist and our study reports three new species for Cyprus waters, namely the blackmouth catshark Dalatias licha, the round fantail stingray Taeniurops grabatus, and the sawback angelshark Squatina aculeata. Our research highlights the need for conservation measures and more studies regarding the highly threatened blackchin guitarfish Glaucostegus cemiculus and the devil ray Mobula mobular, and stresses the importance for training a new generation of observers to strengthen the knowledge and conservation of elasmobranchs in the region.</jats:p

Horizon scanning for invasive alien species with the potential to threaten biodiversity and human health on a Mediterranean island

© 2019, The Author(s). Invasive alien species (IAS) are one of the major drivers of change that can negatively affect biodiversity, ecosystem functions and services and human health; islands are particularly vulnerable to biological invasions. Horizon scanning can lead to prioritisation of IAS to inform decision-making and action; its scale and scope can vary depending on the need. We focussed on IAS likely to arrive, establish and affect biodiversity and human health on the Mediterranean island of Cyprus. The scope of the horizon scanning was the entire island of Cyprus. We used a two-step consensus-building process in which experts reviewed and scored lists of alien species on their likelihood of arrival, establishment and potential to affect biodiversity, ecosystems and/or human health in the next 10 years. We reviewed 225 alien species, considered to be currently absent on Cyprus, across taxa and environments. We agreed upon 100 species that constituted very high, high or medium biodiversity risk, often arriving through multiple pathways of introduction. The remaining 125 species were ranked as low risk. The potential impacts on human health were documented for all 225 species; 82 species were considered to have a potentially negative impact on human health ranging from nuisance to disease transmission. The scope of the horizon scanning was the entire island of Cyprus, but the thematic groups also considered the relevance of the top 100 species to the Sovereign Base Areas of Cyprus, given their differing governance. This horizon scan provides the first systematic exercise to identify invasive alien species of potential concern to biodiversity and ecosystems but also human health within the Mediterranean region. The process and outcomes should provide other islands in the region and beyond with baseline data to improve IAS prioritisation and management

Nonlinearity and Topology

The interplay of nonlinearity and topology results in many novel and emergent properties across a number of physical systems such as chiral magnets, nematic liquid crystals, Bose-Einstein condensates, photonics, high energy physics, etc. It also results in a wide variety of topological defects such as solitons, vortices, skyrmions, merons, hopfions, monopoles to name just a few. Interaction among and collision of these nontrivial defects itself is a topic of great interest. Curvature and underlying geometry also affect the shape, interaction and behavior of these defects. Such properties can be studied using techniques such as, e.g. the Bogomolnyi decomposition. Some applications of this interplay, e.g. in nonreciprocal photonics as well as topological materials such as Dirac and Weyl semimetals, are also elucidated

Magnetic properties of ultrathin discontinuous Co/Pt multilayers: Comparison with short-range ordered and isotropic CoPt 3 films

International audienc

Magnetic properties of ultrathin discontinuous Co/Pt multilayers: Comparison with short-range ordered and isotropic CoPt 3 films

International audienc

Favorable late survival after aortic surgery under straight deep hypothermic circulatory arrest

Background: Surgical and cerebral protection strategies in aortic arch surgery remain under debate. Perioperative results using deep hypothermic circulatory arrest (DHCA) have been associated with favorable short-term mortality and stroke rates. The present study focuses on late survival in patients undergoing aortic surgery using DHCA. Methods: A total of 613 patients (mean age, 63.7 years) underwent aortic surgery between January 2003 and December 2015 using DHCA, with 77.3% undergoing hemiarch replacement and 20.4% undergoing arch replacement, with a mean DHCA duration of 29.7 +/- 8.5 minutes (range, 10-62 minutes). We examined follow-up extending up to a mean of 3.8 +/- 3.4 years (range, 0-14.1 years). Results: Operative mortality was 2.9%, and the stroke rate was 2%. Survival was 92.2% at 1 year and 81.5% at 5 years, significantly lower than the values in an age-and sex-matched reference population. In elective, nondissection first-time surgeries (n = 424), survival was similar to that of the reference group. Acute type A aortic dissection (hazard ratio [HR], 4.84; P = .000), redo (HR, 4.12; P = .000), and descending aortic pathology (HR, 5.54: P = .000) were independently associated with reduced 1-year survival. Beyond 1 year, age (HR, 1.07; P = .000), major complications (HR, 3.11; P = .000), and atrial fibrillation (HR, 2.47; P = .006) were independently associated with poor survival. DHCA time was not significantly associated with survival in multivariable analysis. Conclusions: Aortic surgery with DHCA can be performed with favorable late survival, with the duration of DHCA period having only a limited impact. However, these results cannot be generalized for very long durations of DHCA (>50 minutes), when perfusion methods may be preferable. In elective, nondissection first-time surgeries, a late survival comparable to that in a reference population can be achieved. Early survival is adversely affected by aortic dissection, redo status, and disease extent