Measuring measuring: Toward a theory of proficiency with the Constructing Measures framework

This paper is relevant to measurement educators who are interested in the variability of understanding and use of the four building blocks in the Constructing Measures framework (Wilson, 2005). It proposes a uni-dimensional structure for understanding Wilson’s framework, and explores the evidence for and against this conceptualization. Constructed and fixed choice response items are utilized to collect responses from 72 participants who range in experience and expertise with constructing measures. The data was scored by two raters and was analyzed with the Rasch partial credit model using ConQuest (1998). Guided by the 1999 Testing Standards, analyses of validity and reliability evidence provide support for the construct theory and limited uses of the instrument pending item design modifications

Feeling the future of eyewitness research

The authors have no conflicts of interest to disclose. The data were presented at the 2020 meeting of the Psychonomic Society. This study was supported by a grant from Arnold Ventures. The funding source had no role other than financial support.Peer reviewe

Subsurface Inclusion Quantification Using Multi-Frequency Ultrasonic Surface Waves

Rolling contact fatigue (RCF) is one of the major sources of subsurface-initiated spalling in bearing components. These types of spalls initiate in regions where microcracks are formed due to a localized increase in stress from inclusions near the surface. Ultrasonic bulk inspection is a powerful method to detect defects in a large volume of steel. However, inclusions near the surface of a sample can elude detection because reflections from the inclusion can be masked by reflections from the sample surface. This limitation can be eliminated if ultrasonic surface wave methods are used for inspection. Surface waves have material displacements localized near the sample surface but decay with depth giving an effective inspection of depth on the order of the wavelength. Ultrasonic scattering from inclusions also is wavelength dependent and these two aspects can complicate the interpretation of ultrasonic experimental data. In this presentation, a model is described for the scattering of a surface wave by a subsurface spherical inclusion. The amplitude-versus-depth profile of a surface wave is combined with the solution for the scattering of a shear wave from a spherical scatterer in order to approximate the problem of interest. Trends of reflected amplitude with respect to inspection frequency, inclusion depth, and inclusion diameter are discussed first. Then a necessary calibration experiment is described that uses subsurface defects of known size created using femtosecond laser machining. A model of the calibration sample allows measurements on unknown samples to be interpreted quantitatively. The final analysis shows that the reflected amplitude from multiple frequency measurements can be used to characterize the size and depth of the subsurface inclusions

Systematic Renormalization in Hamiltonian Light-Front Field Theory

We develop a systematic method for computing a renormalized light-front field theory Hamiltonian that can lead to bound states that rapidly converge in an expansion in free-particle Fock-space sectors. To accomplish this without dropping any Fock sectors from the theory, and to regulate the Hamiltonian, we suppress the matrix elements of the Hamiltonian between free-particle Fock-space states that differ in free mass by more than a cutoff. The cutoff violates a number of physical principles of the theory, and thus the Hamiltonian is not just the canonical Hamiltonian with masses and couplings redefined by renormalization. Instead, the Hamiltonian must be allowed to contain all operators that are consistent with the unviolated physical principles of the theory. We show that if we require the Hamiltonian to produce cutoff-independent physical quantities and we require it to respect the unviolated physical principles of the theory, then its matrix elements are uniquely determined in terms of the fundamental parameters of the theory. This method is designed to be applied to QCD, but for simplicity, we illustrate our method by computing and analyzing second- and third-order matrix elements of the Hamiltonian in massless phi-cubed theory in six dimensions.Comment: 47 pages, 6 figures; improved referencing, minor presentation change

Systematic Renormalization in Hamiltonian Light-Front Field Theory: The Massive Generalization

Hamiltonian light-front field theory can be used to solve for hadron states in QCD. To this end, a method has been developed for systematic renormalization of Hamiltonian light-front field theories, with the hope of applying the method to QCD. It assumed massless particles, so its immediate application to QCD is limited to gluon states or states where quark masses can be neglected. This paper builds on the previous work by including particle masses non-perturbatively, which is necessary for a full treatment of QCD. We show that several subtle new issues are encountered when including masses non-perturbatively. The method with masses is algebraically and conceptually more difficult; however, we focus on how the methods differ. We demonstrate the method using massive phi^3 theory in 5+1 dimensions, which has important similarities to QCD.Comment: 7 pages, 2 figures. Corrected error in Eq. (11), v3: Added extra disclaimer after Eq. (2), and some clarification at end of Sec. 3.3. Final published versio

Corrosion of Civil War Era Sub Marine Explorer—Part 1

The Sub Marine Explorer is one of five submersibles (submarines) constructed prior to 1870 that have survived either in museums or as in situ archaeological sites around the world. Since 1869, the wreck of Explorer has emerged at low tide on the beach of Isla San Telmo, Archipiélago de las Perlas, Panama, located ~75 km southwest of Panama City in the Bay of Panama. In 2001, James Delgado visited the site. Locals described the wreck as a World War II-era Japanese midget submarine. Delgado consulted with Richard Wills, an expert on American Civil War submarines, and confirmed that the well-preserved wreck was the Sub Marine Explorer from the Civil War period

Corrosion of Civil War Era \u3ci\u3eSub Marine Explorer\u3c/i\u3e—Part 2

The Sub Marine Explorer was designed and built by Julius H. Kroehl, who was born in Prussia in 1820. After migrating to the United States in 1838 and becoming a citizen, he served in the Union Navy (United States Navy during the Civil War) as an underwater demolitions expert. He left the Navy in 1863 and began designing a “sub-marine” that would facilitate Union forces’ mine removal and obstruction clearance. At the end of the Civil War, he became an engineer for the Pacific Pearl Co., an organization interested in using the craft to recover pearls from deep sea oyster beds in the Bay of Panama. Decompression sickness (the bends), unknown at the time, began to affect the crew in 1869, which led to the abandonment of Explorer in the tidal zone of St. Elmo’s Island (Isla San Telmo) in the Archipielago de las Perlas, Panama

Corrosion of Civil War Era Sub Marine Explorer—Part 1

The Sub Marine Explorer is one of five submersibles (submarines) constructed prior to 1870 that have survived either in museums or as in situ archaeological sites around the world. Since 1869, the wreck of Explorer has emerged at low tide on the beach of Isla San Telmo, Archipiélago de las Perlas, Panama, located ~75 km southwest of Panama City in the Bay of Panama. In 2001, James Delgado visited the site. Locals described the wreck as a World War II-era Japanese midget submarine. Delgado consulted with Richard Wills, an expert on American Civil War submarines, and confirmed that the well-preserved wreck was the Sub Marine Explorer from the Civil War period