Magnetic ripple domain structure in FeGa/MgO thin films

The magnetic domain structure is studied in epitaxial Fe$_{100-x}$Ga$_x$/MgO(001) films with 0 $<$ x $<$ 30 and thicknesses below 60 nm by magnetic force microscopy. For low gallium content, domains with the magnetization lying in the film plane and domain walls separating micrometric areas are observed. Above x $\approx$ 20, the magnetic contrast shows a fine corrugation, ranging from 300 to 900 nm, suggesting a ripple substructure with a periodic oscillation of the magnetization. We discuss the presence of a random magnetic anisotropy contribution, that superimposed to the cubic coherent anisotropy, is able to break the uniform orientation of the magnetization. The origin of that random anisotropy is attributed to several factors: coexistence of crystal phases in the films, inhomogeneous distribution of both internal strain and Ga-Ga next nearest neighbor pairs and interface magnetic anisotropy due to the Fe-O bond.Comment: 9 pages, 3 figure

An approach to research-based design of teaching-learning sequences in the context of physics education: Theoretical frameworks, pedagogical methods, and examples of Data Analysis

In this paper we discuss an example of the research approaches practiced at the University of Palermo Physics Education Research Group (UoPPERG). Particularly, we discuss the design and development with groups of high school students of two Teaching-Learning Sequences (TLSs) on surface phenomena in liquids, and the data collection and analysis methods. In the introduction, we briefly discuss the educational reconstruction model, that we use as a theoretical framework for the designing of the TLSs, and a pedagogical methodology that in the last years has gained consensus among educators, i.e., active learning. Some considerations on active learning pedagogical and cognitive psychology foundations are also made. The main aim of the TLSs is to improve students' learning of surface phenomena, a topic that is quite relevant in Physics and other scientific and technical fields. We provide a research-based, conceptual scheme of what we mean by "improvement of students' learning", and present the TLSs phases, that are based on the well-known inquiry-and investigation-based learning approaches, that are science-specific applications of the general idea of active learning. Then, we describe some methods we use in our researches to collect and give an example of the data analysis needed to study the progression of student learning, with respect to the conceptual scheme provided, and of some of the results obtained

Analysis of sustained long-period activity at Etna Volcano, Italy

Following the installation of a broadband network on Mt. Etna, sustained Long- Period (LP) activity was recorded accompanying a period of total quiescence and the subsequent onset of the 2004–2005 effusive episode. From c. about 56000 events detected by an automatic classification procedure, we analyse a subset of about 3000 signals spanning the December 17th, 2003–September 25th, 2004, time interval. LP spectra are characterised by several, unevenly-spaced narrow peaks spanning the 0.5–10 Hz frequency band. These peaks are common to all the recording sites of the network, and different from those associated with tremor signals. Throughout the analysed time interval, LP spectra and waveforms maintain significant similarity, thus indicating the involvement of a non-destructive source process that we interpret in terms of the resonance of a fluid-filled buried cavity. Polarisation analysis indicates radiation from a non-isotropic source involving large amounts of shear. Concurrently with LP signals, recordings from the summit station also depict Very-Long-Period (VLP) pulses whose rectilinear motion points to a region located beneath the summit craters at depths ranging between 800 and 1100 m beneath the surface. Based on a refined repicking of similar waveforms, we obtain robust locations for a selected subset of the most energetic LP events from probabilistic inversion of travel-times calculated for a 3D heterogenous structure. LP sources cluster in a narrow volume located beneath the summit craters, and extending to a maximum depth of ≈800 m beneath the surface. No causal relationships are observed between LP, VLP and tremor activities and the onset of the 2004–2005 lava effusions, thus indicating that magmatic overpressure played a limited role in triggering this eruption. These data represent the very first observation of LP and VLP activity at Etna during non-eruptive periods, and open the way to the quantitative modelling of the geometry and dynamics of the shallow plumbing system

Modeling and control of a modular iron bird

This paper describes the control architecture and the control laws of a new concept of Modular Iron Bird aimed at reproducing flight loads to test mobile aerodynamic control surface actuators for small and medium size aircraft and Unmanned Aerial Vehicles. The iron bird control system must guarantee the actuation of counteracting forces. On one side, a hydraulic actuator simulates the hinge moments acting on the mobile surface due to aerodynamic and inertial effects during flight; on the other side, the actuator to be tested applies an active hinge moment to control the angular position of the same surface. Reference aerodynamic and inertial loads are generated by a flight simulation module to reproduce more realistic conditions arising during operations. The design of the control action is based on a dynamic model of the hydraulic plant used to generate loads. This system is controlled using a Proportional Integral Derivative control algorithm tuned with an optimization algorithm taking into account the closed loop dynamics of the actuator under testing, uncertainties and disturbances in the controlled plant. Numerical simulations are presented to show the effectiveness of the proposed architecture and control laws

Incorporating Biotic Information in Species Distribution Models: A Coregionalized Approach

In this work, we discuss the use of a methodological approach for modelling spatial relationships among species by means of a Bayesian spatial coregionalized model. Inference and prediction is performed using the integrated nested Laplace approximation methodology to reduce the computational burden. We illustrate the performance of the coregionalized model in species interaction scenarios using both simulated and real data. The simulation demonstrates the better predictive performance of the coregionalized model with respect to the univariate models. The case study focus on the spatial distribution of a prey species, the European anchovy (Engraulis encrasicolus), and one of its predator species, the European hake (Merluccius merluccius), in the Mediterranean sea. The results indicate that European hake and anchovy are positively associated, resulting in improved model predictions using the coregionalized model.Postprin

Use of Roadside Deer Removal to Reduce Deer–Vehicle Collisions

Identification of management tools to reduce the incidence of deer–vehicle collisions (DVCs) is important to improve motorist safety. Sharpshooting to reduce white-tailed deer (Odocoileus virginianus; deer) along roads has proven successful in urban situations but has not been evaluated in undeveloped areas. We used a before-after-control-impact (BACI) design to evaluate the use of sharpshooting to reduce DVCs along roads on the uninhabited U.S. Department of Energy’s Savannah River Site, South Carolina, USA, during 2011–2017. We removed 242 deer from 4 treatment roads during 2015 and 2016, with 2-year removal rates per road averaging 5.0 deer/km of road (range 4.0–5.8). We monitored accident rates as DVCs per million vehicle-km traveled (VKT) during annual cycles (March–February) following the initial removal and during the 7 months (March–September) following removals in spring and the 5 months (October–February) following removals in fall. The response in accident rates varied among the annual cycle, spring, and fall. The BACI effect indicated that removal treatments reduced accident rate by 1.184 DVCs per million VKT (P = 0.081) over the annual cycle and by 1.528 DVCs per million VKT (P = 0.023) following spring removals, but following fall removals we detected no effect (P = 0.541). Relative to the pre-removal accident rate for removal roads, the estimated treatment effect on an annual basis equated to a 39.4% reduction in accidents and during spring equated to a 50.8% reduction in accidents. We conclude that sharpshooting along roads in undeveloped areas can be a viable tool to reduce DVCs and can be useful in areas where population control via hunter harvest is not practical or desirable

Temperature behavior of radiochromic poly(vinyl-alcohol)&#8211;glutaraldehyde Fricke gel dosimeters in practice

The use of synthetic gel matrices prepared with poly(vinyl-alcohol) (PVA) cross-linked by glutaraldehyde (GTA) contributed to enhance the interest toward radiochromic Fricke gel (FG) dosimeters. As it occurs in several chemical dosimeters, the response of PVA-GTA Fricke gels could be affected by temperature. Aim of this work is to study the dependence of the dosimetric properties of PVA-GTA Fricke gel dosimeters both on the irradiation temperature and on temperature changes possibly occurring between the irradiation and readout phases. Such effects were investigated by means of magnetic resonance imaging (MRI) and optical absorbance (OA) measurements. The results did not reveal any significant dependence of the sensitivity of the dosimeters on the irradiation temperature in the investigated interval 20\ub0C-35\ub0C. By contrast, auto-oxidation phenomena confirmed to be a critical aspect for FG dosimeters, also in case of use of PVA matrix. The extent such phenomena, that might impair the accuracy of dose estimations, proved to critically depend on the temperature at which FG dosimeters are subjected before and after irradiation, as well as on the duration of possible thermal-stress

Use and misuse of multivariable approaches in interventional cardiology studies on drug-eluting stents: a systematic review.

Aims: Randomized clinical trials (RCTs) are the most reliable evidence, even if they require important resource and logistic efforts. Large, cost-free and real-world datasets may be easily accessed yielding to observational studies, but such analyses often lead to problematic results in the absence of careful methods, especially from a statistic point of view. We aimed to appraise the performance of current multivariable approaches in the estimation of causal treatment and effects in studies focusing on drug-eluting stents (DES). Methods and Results: Pertinent studies published in the literature were searched, selected, abstracted, and appraised for quality and validity features. Six studies with a logistic regression were included, all of them reporting more than 10 events for covariates and different length of follow-up, with an overall low risk of bias. Most of the 15 studies with a Cox proportional hazard analysis had a different follow-up, with less than 10 events for covariates, yielding an overall low or moderate risk of bias. Sixteen studies with propensity score were included: the most frequent method for variable selection was logistic regression, with underlying differences in follow-up and less than 10 events for covariate in most of them. Most frequently, calibration appraisal was not reported in the studies, on the contrary of discrimination appraisal, which was more frequently performed. In seventeen studies with propensity and matching, the latter was most commonly performed with a nearest neighbor-matching algorithm yet without appraisal in most of the studies of calibration or discrimination. Balance was evaluated in 46% of the studies, being obtained for all variables in 48% of them. Conclusions: Better exploitation and methodological appraisal of multivariable analysis is needed to improve the clinical and research impact and reliability of nonrandomized studies. (J Interven Cardiol 2012;**:1-1

Crystal structure and local ordering in epitaxial Fe100−x_{100-x}Gax_x/MgO(001) films

In this work we present a study of the structural properties of Fe$_{100-x}$ Ga$_x$ grown by Molecular Beam Epitaxy on Mg0(100). We combine long range and local/chemically selective X-ray probes (X-ray Diffraction and X-ray absorption spectroscopy) together with real space imaging by means of Transmission Electron Microscopy and surface sensitive $in situ$ Reflected High Energy Electron Diffraction. For substrate temperature $T_s$ below 400 $^o$C we obtain $bcc$ films while, for $x \approx$ 24 and $T_s \geq$ 400$^o$C the nucleation of the $fcc$ phase is observed. For both systems a Ga anticlustering or local range ordering phenomenon appears. The Ga/Fe composition in the first and second coordination shells of the $bcc$ films is different from that expected for a random Ga distribution and is close to a D0$_3$-like ordered phase, leading to a minimization of the number of Ga-Ga pairs. On the other side, a true long-range D0$_3$ phase is not observed indicating that atomic ordering only occurs at a local scale. Overall, the epitaxial growth procedure presented in this work, first, avoids the formation of a long range ordered D0$_3$ phase, which is known to be detrimental magnetostrictive properties, and second, demonstrates the possibility of growing $fcc$ films at temperatures much smaller than those required to obtain bulk $fcc$ samples.Comment: 21 pages, 7 figure