Surface Roughness Dominated Pinning Mechanism of Magnetic Vortices in Soft Ferromagnetic Films

Although pinning of domain walls in ferromagnets is ubiquitous, the absence of an appropriate characterization tool has limited the ability to correlate the physical and magnetic microstructures of ferromagnetic films with specific pinning mechanisms. Here, we show that the pinning of a magnetic vortex, the simplest possible domain structure in soft ferromagnets, is strongly correlated with surface roughness, and we make a quantitative comparison of the pinning energy and spatial range in films of various thickness. The results demonstrate that thickness fluctuations on the lateral length scale of the vortex core diameter, i.e. an effective roughness at a specific length scale, provides the dominant pinning mechanism. We argue that this mechanism will be important in virtually any soft ferromagnetic film.Comment: 4 figure

W/SiC x-ray multilayers optimized for use above 100 keV

We have developed a new depth-graded multilayer system comprising W and SiC layers, suitable for use as hard x-ray reflective coatings operating in the energy range 100-200 keV. Grazing-incidence x-ray reflectance at E = 8 keV was used to characterize the interface widths, as well as the temporal and thermal stability in both periodic and depth-graded W/SiC structures, whereas synchrotron radiation was used to measure the hard x-ray reflectance of a depth-graded multilayer designed specifically for use in the range E ~150-170 keV. We have modeled the hard x-ray reflectance using newly derived optical constants, which we determined from reflectance versus incidence angle measurements also made using synchrotron radiation, in the range E = 120-180 keV. We describe our experimental investigation in detail, compare the new W/SiC multilayers with both W/Si and W/B4C films that have been studied previously, and discuss the significance of these results with regard to the eventual development of a hard x-ray nuclear line telescope

Ocean model-based covariates improve a marine fish stock assessment when observations are limited

The productivity of many fish populations is influenced by the environment, but developing environment-linked stock assessments remain challenging and current management of most commercial species assumes that stock productivity is time-invariant. In the Northeast United States, previous studies suggest that the recruitment of Southern New England-Mid Atlantic yellowtail flounder is closely related to the strength of the Cold Pool, a seasonally formed cold water mass on the continental shelf. Here, we developed three new indices that enhance the characterization of Cold Pool interannual variations using bottom temperature from a regional hindcast ocean model and a global ocean data assimilated hindcast. We associated these new indices to yellowtail flounder recruitment in a state–space, age-structured stock assessment framework using the Woods Hole Assessment Model. We demonstrate that incorporating Cold Pool effects on yellowtail flounder recruitment reduces the retrospective patterns and may improve the predictive skill of recruitment and, to a lesser extent, spawning stock biomass. We also show that the performance of the assessment models that incorporated ocean model-based indices is improved compared to the model using only the observation-based index. Instead of relying on limited subsurface observations, using validated ocean model products as environmental covariates in stock assessments may both improve predictions and facilitate operationalization.publishedVersio

Enhancing energy and glucose metabolism by disrupting triglyceride synthesis: Lessons from mice lacking DGAT1

Although the ability to make triglycerides is essential for normal physiology, excess accumulation of triglycerides results in obesity and is associated with insulin resistance. Inhibition of triglyceride synthesis, therefore, may represent a feasible strategy for the treatment of obesity and type 2 diabetes. Acyl CoA:diacylglycerol acyltransferase 1 (DGAT1) is one of two DGAT enzymes that catalyze the final reaction in the known pathways of mammalian triglyceride synthesis. Mice lacking DGAT1 have increased energy expenditure and insulin sensitivity and are protected against diet-induced obesity and glucose intolerance. These metabolic effects of DGAT1 deficiency result in part from the altered secretion of adipocyte-derived factors. Studies of DGAT1-deficient mice have helped to provide insights into the mechanisms by which cellular lipid metabolism modulates systemic carbohydrate and insulin metabolism, and a better understanding of how DGAT1 deficiency enhances energy expenditure and insulin sensitivity may identify additional targets or strategies for the treatment of obesity and type 2 diabetes

Exhaustive and Efficient Constraint Propagation: A Semi-Supervised Learning Perspective and Its Applications

This paper presents a novel pairwise constraint propagation approach by decomposing the challenging constraint propagation problem into a set of independent semi-supervised learning subproblems which can be solved in quadratic time using label propagation based on k-nearest neighbor graphs. Considering that this time cost is proportional to the number of all possible pairwise constraints, our approach actually provides an efficient solution for exhaustively propagating pairwise constraints throughout the entire dataset. The resulting exhaustive set of propagated pairwise constraints are further used to adjust the similarity matrix for constrained spectral clustering. Other than the traditional constraint propagation on single-source data, our approach is also extended to more challenging constraint propagation on multi-source data where each pairwise constraint is defined over a pair of data points from different sources. This multi-source constraint propagation has an important application to cross-modal multimedia retrieval. Extensive results have shown the superior performance of our approach.Comment: The short version of this paper appears as oral paper in ECCV 201

Panic bank runs

We provide experimental evidence that panic bank runs occur in the absence of problems with fundamentals and coordination failures among depositors, the two main culprits identified in the literature. Depositors withdraw when they observe that others do so, even when theoretically they should not. Our findings suggest that panic also manifests itself in the beliefs of depositors, who overestimate the probability that a bank run is underway. Loss-aversion has a predictive power on panic behavior, while risk or ambiguity aversion do not

Turbulent velocity measurements in open channel bores

In an open channel, a sudden rise in free-surface elevation is associated with the development of a bore. The bore front is a hydrodynamic shock with a sharp discontinuity in terms of water depth and velocity field. In this study, some turbulent velocity measurements were conducted in breaking bores. The unsteady turbulent properties were analysed using three methods: an ensemble average (EA) technique based upon 20 repeated experiments, a variable interval time average (VITA) method based upon a single experiment, and the variable interval time average (VITA) method averaged over 20 experimental runs. The instantaneous free-surface and velocity measurements showed a marked effect of the bore front passage. The longitudinal velocity components were always characterised by a rapid flow deceleration at all vertical elevations, and some large fluctuations of all velocity components were recorded beneath the surge. The EA and VITA methods showed some comparable long-term trends superposed to some rapid turbulent fluctuations, as well as close results in terms of the turbulent Reynolds stress components. The VITA data based upon a single run presented some differences with the EA median results, but all methods exhibited comparable long-term trends superposed to rapid turbulent fluctuations. (C) 2011 Elsevier Masson SAS. All rights reserved

On the Regularity Property of Differential Polynomials Modulo Regular Differential Chains

International audienceThis paper provides an algorithm which computes the normal form of a rational differential fraction modulo a regular differential chain if, and only if, this normal form exists. A regularity test for polynomials modulo regular chains is revisited in the nondifferential setting and lifted to differential algebra. A new characterization of regular chains is provided

Cardiovascular and cerebrovascular events among patients receiving omalizumab: Results from EXCELS, a prospective cohort study in moderate to severe asthma

BackgroundEXCELS, a postmarketing observational cohort study, was a commitment to the US Food and Drug Administration to assess the long-term safety of omalizumab in an observational setting, focusing predominantly on malignancies.ObjectiveThe aim of this study was to examine a potential association between omalizumab and cardiovascular (CV)/cerebrovascular (CBV) events in EXCELS.MethodsPatients (≥12 years of age) with moderate to severe allergic asthma and who were being treated with omalizumab (n = 5007) or not (n = 2829) at baseline were followed up for ≤5 years. Analyses included overall CV/CBV events, but focused on the subset of arterial thromboembolic events (ATEs), comprising CV death, myocardial infarction, ischemic stroke, transient ischemic attack, and unstable angina. A prespecified analysis of the end point of ATE was conducted to control for available potential confounders. A blinded independent expert panel adjudicated all events.ResultsAt baseline, the 2 cohorts had similar demographic characteristics, but severe asthma was more common in the omalizumab versus the non-omalizumab group (50% vs 23%). Omalizumab-treated patients had a higher rate of CV/CBV serious adverse events (13.4 per 1,000 person years [PYs]) than did non–omalizumab-treated patients (8.1 per 1,000 PYs). The ATE rates per 1,000 PYs were 6.66 (101 patients/15,160 PYs) in the omalizumab cohort and 4.64 (46 patients/9,904 PYs) in the non-omalizumab cohort. After control for available confounding factors, the hazard ratio was 1.32 (95% CI, 0.91-1.91).ConclusionThis observational study demonstrated a higher incidence rate of CV/CBV events in the omalizumab versus the non-omalizumab cohort. Differences in asthma severity between cohorts likely contributed to this imbalance, but some increase in risk cannot be excluded

Reordering Hierarchical Tree Based on Bilateral Symmetric Distance

BACKGROUND: In microarray data analysis, hierarchical clustering (HC) is often used to group samples or genes according to their gene expression profiles to study their associations. In a typical HC, nested clustering structures can be quickly identified in a tree. The relationship between objects is lost, however, because clusters rather than individual objects are compared. This results in a tree that is hard to interpret. METHODOLOGY/PRINCIPAL FINDINGS: This study proposes an ordering method, HC-SYM, which minimizes bilateral symmetric distance of two adjacent clusters in a tree so that similar objects in the clusters are located in the cluster boundaries. The performance of HC-SYM was evaluated by both supervised and unsupervised approaches and compared favourably with other ordering methods. CONCLUSIONS/SIGNIFICANCE: The intuitive relationship between objects and flexibility of the HC-SYM method can be very helpful in the exploratory analysis of not only microarray data but also similar high-dimensional data