Mechanical vaccum pumps

This presentation gives an overview of the technology of contemporary primary and secondary mechanical vacuum pumps. For reference a brief history of vacuum and a summary of important and basic vacuum concepts are first presented

Exploring the S-Matrix of Massless Particles

We use the recently proposed generalised on-shell representation for scattering amplitudes and a consistency test to explore the space of tree-level consistent couplings in four-dimensional Minkowski spacetime. The extension of the constructible notion implied by the generalised on-shell representation, i.e. the possibility to reconstruct at tree level all the scattering amplitudes from the three-particle ones, together with the imposition of the consistency conditions at four-particle level, allow to rediscover all the known theories and their algebra structure, if any. Interestingly, this analysis seems to leave room for high-spin couplings, provided that at least the requirement of locality is weakened. We do not claim to have found tree-level consistent high-spin theories, but rather that our methods show signatures of them and very likely, with a suitable modification, they can be a good framework to perform a systematic search.Comment: 44 pages, 1 figur

Implementation of a Large System-Wide Hepatitis C Virus Screening and Linkage to Care Program for Baby Boomers.

BackgroundWe implemented and evaluated a large health system-wide hepatitis C virus (HCV) screening and linkage to care program for persons born between 1945 and 1965 ("baby boomers").MethodsAn electronic health record (EHR) clinical decision support (CDS) tool for HCV screening for baby boomers was introduced in August 2015 for patients seen in the outpatient University of California, Los Angeles healthcare system setting. An HCV care coordinator was introduced in January 2016 to facilitate linkage to HCV care. We compared HCV testing in the year prior (August 2014-July 2015) to the year after (August 2015-July 2016) implementation of the CDS tool. Among patients with reactive HCV antibody testing, we compared outcomes related to the care cascade including HCV ribonucleic acid (RNA) testing, HCV RNA positivity, and linkage to HCV specialty care.ResultsDuring the study period, 19606 participants were screened for HCV antibody. Hepatitis C virus antibody screening increased 145% (from 5676 patients tested to 13930 tested) after introduction of the CDS intervention. Screening increased across all demographic groups including age, sex, and race/ethnicity, with the greatest increases among those in the older age groups. The addition of an HCV care coordinator increased follow-up HCV RNA testing for HCV antibody positive patients from 83% to 95%. Ninety-four percent of HCV RNA positive patients were linked to care postimplementation.ConclusionsIntroduction of an EHR CDS tool and care coordination markedly increased the number of baby boomers screened for HCV, rates of follow-up HCV RNA testing, and linkage to specialty HCV care for patients with chronic HCV infection

Isotropic-medium three-dimensional cloaks for acoustic and electromagnetic waves

We propose a generalization of the two-dimensional eikonal-limit cloak derived from a conformal transformation to three dimensions. The proposed cloak is a spherical shell composed of only isotropic media; it operates in the transmission mode and requires no mirror or ground plane. Unlike the well-known omnidirectional spherical cloaks, it may reduce visibility of an arbitrary object only for a very limited range of observation angles. In the short-wavelength limit, this cloaking structure restores not only the trajectories of incident rays, but also their phase, which is a necessary ingredient to complete invisibility. Both scalar-wave (acoustic) and transverse vector-wave (electromagnetic) versions are presented.Comment: 17 pages, 12 figure

pi-N charge exchange and pi(+)-pi(0) scattering at low energies

pi-N and pi-pi interactions near threshold are uniquely sensitive to the chiral symmetry breaking part of the strong interaction. The pi-N sigma-term value with its implications for nucleon quark structure and the recent controversy concerning the size of the scalar quark condensate have renewed the experimental interest in these two fundamental systems. We report new differential cross sections for the reaction $pi^-p \to \pi^0n$ at 27.5 MeV pion incident kinetic energy, measured between $\theta_{CM} = 0^\circ$ and $55^\circ$. Our results are in excellent agreement with the existing comprehensive pi-N phase shift analysis. We also report on a Chew-Low analysis of exclusive $\pi^+ p \to \pi^+\pi^0p$ data at 260 MeV pion incident energy.Comment: Talk given by D. Pocanic at QULEN97, Osaka, 20-23 May 1997; 4 pages, 2 PostScript figures, writen in LaTeX 2e, uses packages "epsfig" and "espcrc1

Optimizing Chew and Chen's Pitch-Spelling Algorithm

Pitch-spelling algorithms attempt to compute the correct pitch names (e.g., C#4, Bb5) of the notes in a passage of tonal music, when given only the onset time, MIDI note number, and possibly the duration and voice of each note. This article reports on a study in which Chew and Chen’s (2003a, 2003b, 2005) pitch-spelling algorithm was re-implemented and then optimized by running it with a range of different parameter value combinations on a test corpus containing 195,972 notes and consisting of 216 movements from works by eight Baroque and Classical composers. The results of this evaluation cast doubt upon some of the claims made by Chew and Chen that were based on results obtained by running their algorithm on a much smaller test corpus containing only 4,462 notes and consisting of just two movements from sonatas by Beethoven and You-Di Huang’s Song of Ali-Shan. The results presented here suggest that Chew and Chen’s algorithm could be simplified in various ways without compromising its performance