Perturbation of magnetostatic modes observed by ferromagnetic resonance force microscopy

Magnetostatic modes of yttrium iron garnet (YIG) films are investigated by ferromagnetic resonance force microscopy. A thin-film "probe" magnet at the tip of a compliant cantilever introduces a local inhomogeneity in the internal field of the YIG sample. This influences the shape of the sample's magnetostatic modes, thereby measurably perturbing the strength of the force coupled to the cantilever. We present a theoretical model that explains these observations; it shows that the tip-induced variation of the internal field creates either a local "potential barrier" or "potential well" for the magnetostatic waves. The data and model together indicate that local magnetic imaging of ferromagnets is possible, even in the presence of long-range spin coupling, through the introduction of localized magnetostatic modes predicted to arise from sufficiently strong tip fields

A review of low density porous materials used in laser plasma experiments

金沢大学先端科学・社会共創推進機構This review describes and categorizes the synthesis and properties of low density porous materials, which are commonly referred to as foams and are utilized for laser plasma experiments. By focusing a high-power laser on a small target composed of these materials, high energy and density states can be produced. In the past decade or so, various new target fabrication techniques have been developed by many laboratories that use high energy lasers and consequently, many publications and reviews followed these developments. However, the emphasis so far has been on targets that did not utilize low density porous materials. This review therefore, attempts to redress this balance and endeavors to review low density materials used in laser plasma experiments in recent years. The emphasis of this review will be on aspects of low density materials that are of relevance to high energy laser plasma experiments. Aspects of low density materials such as densities, elemental compositions, macroscopic structures, nanostructures, and characterization of these materials will be covered. Also, there will be a brief mention of how these aspects affect the results in laser plasma experiments and the constrictions that these requirements put on the fabrication of low density materials relevant to this field. This review is written from the chemists\u27 point of view to aid physicists and the new comers to this field. © 2018 Author(s).Embargo Period 12 month

Bias with respect to socioeconomic status: A closer look at zip code matching in a pneumococcal vaccine effectiveness study

In 2010, 13-valent pneumococcal conjugate vaccine (PCV13) was introduced in the US for prevention of invasive pneumococcal disease in children. Individual-level socioeconomic status (SES) is a potential confounder of the estimated effectiveness of PCV13 and is often controlled for in observational studies using zip code as a proxy. We assessed the utility of zip code matching for control of SES in a post-licensure evaluation of the effectiveness of PCV13 (calculated as [1-matched odds ratio]*100). We used a directed acyclic graph to identify subsets of confounders and collected SES variables from birth certificates, geocoding, a parent interview, and follow-up with medical providers. Cases tended to be more affluent than eligible controls (for example, 48.3% of cases had private insurance vs. 44.6% of eligible controls), but less affluent than enrolled controls (52.9% of whom had private insurance). Control of confounding subsets, however, did not result in a meaningful change in estimated vaccine effectiveness (original estimate: 85.1%, 95% CI 74.8–91.9%; adjusted estimate: 82.5%, 95% CI 65.6–91.1%). In the context of a post-licensure vaccine effectiveness study, zip code appears to be an adequate, though not perfect, proxy for individual SES

Ray A. Wigen Interview

A tape recorded interview of Ray A. Wigen conducted in 1976 by Ray Barello. Dr. Wigen served at Stout from 1933-1966 as a teacher, administrator, and finally as first Dean of the Graduate School. The interview includes discussion of his financial hardships while attending college, student life at Stout, the development of the Graduate College, accreditation problems at Stout, civil defense during World War II, his philosophy of education, involvement with international students, and miscellaneous information

Interview with Ray A. Wigen

A tape recorded interview with Ray Wigen that was conducted in October, 1973. Wigen, born May 22, 1896 in River Falls, Wisconsin, graduated from the River Falls Normal School in 1916. He obtained his bachelor's and Ph. D. from the University of Minnesota. He married Evelyn Zellmer July 3, 1928 in South St. Paul, Minnesota. He taught at Mazeppa, Buffalo, and South St. Paul, MN before joining the faculty at Stout in 1933. He retired from Stout in 1966. He was Dean of Graduate Studies at the time. Wigen Hall, a residence hall on Stout's north campus was named in his honor. Wigen did extensive writing and consulting work in the field of industrial education

The development of empowerment and leadership among youth involved in asset mapping

Research shows that youth have too few opportunities to engage in their community, develop a sense of empowerment, or develop and practice leadership skills and characteristics. This qualitative study examines existing data to better understand the development of empowerment and leadership among high school youth involved in youth asset mapping. As part of an evaluation of a community empowerment project, interviews were conducted with high school youth from three sites and with adults who were either directly or indirectly involved with the youth asset mapping projects. Interviews consisted of focus groups, telephone interviews, and in-person interviews. The findings suggest that a sense of empowerment was partially developed through participation in the youth asset mapping projects. Leadership skills and characteristics appeared to have been developed through involvement in youth asset mapping. The role of the facilitator also influenced the development of empowerment and leadership. Unanticipated themes such as cultural barriers between youth and adults, passion/motivation of youth, and adult recognition of youth emerged as components of adult-youth partnerships that are necessary to address to foster the development of empowerment and leadership among youth

Frequency- and time-domain investigation of the dynamic properties of interlayer-exchange-coupled Ni81Fe19/Ru/Ni81Fe19 thin films

Pulsed inductive microwave magnetometer (PIMM), conventional ferromagnetic resonance (FMR), and vector network analyzer FMR (VNA-FMR) have been used for complementary studies of the various excited modes in exchange-coupled NiFe(30 nm)/Ru(d(Ru))/NiFe(30 nm) films with variable Ru thicknesses d(Ru). For antiferromagnetically coupled layers, two modes, which vary in their relative intensity as a function of the bias field, are detected. These two modes, which are observable simultaneously over a limited range of the bias field with PIMM, are identified as optic and acoustic modes. The mode frequencies and the interlayer exchange coupling are found to oscillate as a function of the Ru layer thickness with a period of 8.5 A. The frequency oscillations of the optic mode are coupling dependent, while those of the acoustic mode are indirectly related to coupling via the canting angle of the layer magnetizations below the saturation. Comparison between PIMM and VNA-FMR in terms of frequency of modes shows good agreement, but the optic mode is observed over a wider field range with VNA-FMR. Furthermore, we clearly observed different behaviors of the FMR linewidths as a function of the spacer thickness for the optic and acoustic modes. In addition, perpendicular standing spin waves have been studied as a function of coupling. The FMR linewidth of the different modes increases with the microwave frequency and typical damping constants of alpha=0.0073 have been measured. The effect of the pulse field amplitudes on the properties of the various excited modes has been simulated and studied experimentally