Evaluation of Cyclic Behavior of Aircraft Turbine Disk Alloys

An evaluation of the cyclic behavior of three aircraft engine turbine disk materials was conducted to compare their relative crack initiation and crack propagation resistance. The disk alloys investigated were Inconel 718, hot isostatically pressed and forged powder metallurgy Rene '95, and as-hot-isostatically pressed Rene '95. The objective was to compare the hot isostatically pressed powder metallurgy alloy forms with conventionally processed superalloys as represented by Inconel 718. Cyclic behavior was evaluated at 650 C both under continuously cycling and a fifteen minute tensile hold time cycle to simulate engine conditions. Analysis of the test data were made to evaluate the strain range partitioning and energy exhaustion concepts for predicting hold time effects on low cycle fatigue

Periodic array-based substrates for surface-enhanced infrared spectroscopy

At the beginning of the 1980s, the first reports of surface-enhanced infrared spectroscopy (SEIRS) surfaced. Probably due to signal-enhancement factors of only 101 to 103, which are modest compared to those of surface-enhanced Raman spectroscopy (SERS), SEIRS did not reach the same significance up to date. However, taking the compared to Raman scattering much larger cross-sections of infrared absorptions and the enhancement factors together, SEIRS reaches about the same sensitivity for molecular species on a surface in terms of the cross-sections as SERS and, due to the complementary nature of both techniques, can valuably augment information gained by SERS. For the first 20 years since its discovery, SEIRS relied completely on metal island films, fabricated by either vapor or electrochemical deposition. The resulting films showed a strong variance concerning their structure, which was essentially random. Therefore, the increase in the corresponding signal-enhancement factors of these structures stagnated in the last years. In the very same years, however, the development of periodic array-based substrates helped SEIRS to gather momentum. This development was supported by technological progress concerning electromagnetic field solvers, which help to understand plasmonic properties and allow targeted design. In addition, the strong progress concerning modern fabrication methods allowed to implement these designs into practice. The aim of this contribution is to critically review the development of these engineered surfaces for SEIRS, to compare the different approaches with regard to their performance where possible, and report further gain of knowledge around and in relation to these structures

Peer-Assisted Learning and Orthopaedic Evaluation Psychomotor Skills

Context: Athletic training educators often anecdotally suggest that athletic training students enhance their learning by teaching their peers. However, peer-assisted learning (PAL) has not been examined within athletic training education to provide evidence for PAL's current use or for its use as a pedagogic tool. Objective: To assess the effectiveness of intentional, formal PAL on the performance of psychomotor skills and to identify students' perceptions of PAL. Design: Randomized, pretest-posttest experimental design. Setting: Athletic Training Research and Education Laboratory. Patients or Other Participants: Fifty-one undergraduate students (27 athletic training majors, 24 nonmajors). Intervention(s): Review sessions led by either an Approved Clinical Instructor or peer tutor. Main Outcome Measure(s): We assessed pretest and posttest performance scores (number of correct skills) and the amount of time to complete the psychomotor skills in 3 categories of orthopaedic evaluation of the hand and wrist for subjects assigned to either a peer tutor or an Approved Clinical Instructor review group. Using the Athletic Training Peer-Assisted Learning Assessment Survey, we evaluated the perceptions of students assigned to the peer-tutor group regarding the benefits of, and preferences for, PAL. Results: Differences in the pretest-posttest skill scores were noted in both groups (P < .05). No differences in the posttest skills scores or the times to perform the skills were seen between the groups. The Athletic Training Peer-Assisted Learning Assessment Survey revealed that most (n = 19, 70.4%) of the subjects felt less anxious when practicing psychomotor skills with peer tutors than with the laboratory instructor, and many students (n = 12, 44.4%) felt more self-confident when practicing psychomotor skills with a peer tutor. Conclusions: Peer-assisted learning appears to be a valid method for improving athletic training psychomotor skills. Peers can be resources for practicing clinical skills and report benefiting from the collaboration. Peer-assisted learning should be deliberately integrated into athletic training education programs to enhance student learning and collaboration

Proteomic techniques to probe the ubiquitin landscape

Protein ubiquitination is a powerful modulator of cellular functions. Classically linked to the degradation of proteins, it also plays a role in intracellular localization, DNA damage response, vesicle fusion events, and the immune and transcriptional responses. Ubiquitin is versatile and can code for several distinct signals, either by adding a single ubiquitin or forming a chain of ubiquitins on the target protein. The enzymatic cascade associated with the cellular process determines the nature of the modification. Numerous efforts have been made for the identification of ubiquitin acceptor sites in the target proteins using genetic, biochemical or mass-spectrometry based proteomic methods, such as affinity-based enrichment of ubiquitinated proteins, and antibody-based enrichment of modified peptides. Modern instrumentation enables quantitative mass-spectrometry strategies to identify and characterize hundreds of ubiquitin substrates in a single analysis making it the dominant method for ubiquitin site detection. Characterization of the inter-ubiquitin connectivity in ubiquitin polymers has also moved into focus, with the field of targeted proteomics techniques proving invaluable for identifying and quantifying linkage types found in such polyubiquitin chains. This review seeks to provide an overview of the many mass-spectrometry based proteomics techniques available for exploring this dynamic field

Where Does Energy R&D Come From? Examining Crowding Out from Environmentally-Friendly R&D

Recent efforts to endogenize technological change in climate policy models demonstrate the importance of accounting for the opportunity cost of climate R&D investments. Because the social returns to R&D investments are typically higher than the social returns to other types of investment, any new climate mitigation R&D that comes at the expense of other R&D investment may dampen the overall gains from induced technological change. Unfortunately, there has been little empirical work to guide modelers as to the potential magnitude of such crowding out effects. This paper considers both the private and social opportunity costs of climate R&D. Addressing private costs, we ask whether an increase in climate R&D represents new R&D spending, or whether some (or all) of the additional climate R&D comes at the expense of other R&D. Addressing social costs, we use patent citations to compare the social value of alternative energy research to other types of R&D that may be crowded out. Beginning at the industry level, we find some evidence of crowding out in sectors active in energy R&D, but not in sectors that do not perform energy R&D. This suggests that funds for energy R&D do not come from other sectors, but may come from a redistribution of research funds in sectors that are likely to perform energy R&D. Given this, we proceed with a detailed look at climate R&D in two sectors – alternative energy and automotive manufacturing. Linking patent data and financial data by firm, we ask whether an increase in alternative energy patents leads to a decrease in other types of patenting activity. We find crowding out for alternative energy firms, but no evidence of crowding out for automotive firms. Finally, we use patent citation data to compare the social value of alternative energy patents to other patents by these firms. Alternative energy patents are cited more frequently, and by a wider range of other technologies, than other patents by these firms, suggesting that their social value is higher.

Ground state cooling of atoms in optical lattices

We propose two schemes for cooling bosonic and fermionic atoms that are trapped in a deep optical lattice. The first scheme is a quantum algorithm based on particle number filtering and state dependent lattice shifts. The second protocol alternates filtering with a redistribution of particles by means of quantum tunnelling. We provide a complete theoretical analysis of both schemes and characterize the cooling efficiency in terms of the entropy. Our schemes do not require addressing of single lattice sites and use a novel method, which is based on coherent laser control, to perform very fast filtering.Comment: 12 pages, 7 figure

The Bouguer-Beer-Lambert Law: Shining Light on the Obscure

The Beer-Lambert law is unquestionably the most important law in optical spectroscopy and indispensable for the qualitative and quantitative interpretation of spectroscopic data. As such, every spectroscopist should know its limits and potential pitfalls, arising from its application, by heart. It is the goal of this work to review these limits and pitfalls, as well as to provide solutions and explanations to guide the reader. This guidance will allow a deeper understanding of spectral features, which cannot be explained by the Beer-Lambert law, because they arise from electromagnetic effects/the wave nature of light. Those features include band shifts and intensity changes based exclusively upon optical conditions, i. e. the method chosen to record the spectra, the substrate and the form of the sample. As such, the review will be an essential tool towards a full understanding of optical spectra and their quantitative interpretation based not only on oscillator positions, but also on their strengths and damping constants