Alternative potentials for the electromagnetic field

The electromagnetic field can be expressed in terms of two complex potentials $\alpha, \beta ,$ which are related to the Debye potentials. The evolution equations for these potentials are derived, which are separable either in parabolic coordinates (leading to the radiation fields) or in radial coordinates (multipole fields). Potentials corresponding to focused wave fields as well as plane waves are discussed. A conserved radiation density can be constructed in terms of these potentials, which is positive (negative) for positive (negative) helicity radiation.Comment: 13 pages, plainTex, slightly amended version of origina

Pure single photon generation by type-I PDC with backward-wave amplification

We explore a promising method of generating pure heralded single photons. Our approach is based on parametric downconversion in a periodically-poled waveguide. However, unlike conventional downconversion sources, the photon pairs are counter-propagating: one travels with the pump beam in the forward direction while the other is backpropagating towards the laser source. Our calculations reveal that these downconverted two-photon states carry minimal spectral correlations within each photon-pair. This approach offers the possibility to employ a new range of downconversion processes and materials like PPLN (previously considered unsuitable due to their unfavorable phasematching properties) to herald pure single photons over a broad frequency range.Comment: 8 pages, 3 figures, minor text changes and reformattin

W.C. Mosley to Mr. Silver, 3 September 1957

Professional correspondenc

Julian C. Mosley, Jr. Oral History

An interview of the Washington University Medical Center Desegregation History Project, conducted by Edwin W. McCleskey and associates, 1990. Approximate Length: 57 minutes. Julian Mosley, the second Black student to graduate from Washington University School of Medicine, discusses his experiences as a student in the 1960s and recruitment strategies and programs for students from minority groups. He begins by explaining why he decided to come to Washington University. He discusses the other Black students in his class and his efforts to recruit more Black students to the medical school. Mosley also discusses the work of Robert Lee as Assistant Dean for Minority Student Affairs and his success at recruiting students. He addresses specific efforts on the part of Lee, other students, and the university that supported minority students, including tutoring and individualized programs. Mosley next discusses the Wessler Committee and later, their recommendations. He addresses the lack of Black professors at Washington University and at the medical school, and the lack of Black students in the residency programs. He also discusses the effects of the Supreme Court case Regents of the University of California v. Bakke on minority student recruitment. He discusses his experience with integration in high school in East St. Louis, in the Air Force Academy, and at Washington University, and his experiences with professional societies and student medical associations and programs. Lastly, Mosley explains what he believes needs to be done to recruit more Black graduate students and faculty, and gives his thoughts for the future

Human Influences on the Northern Yellowstone Range

Humans have continuously inhabited the Northern Yellowstone Range (hereafter referred to as the Northern Range1 ) inside and outside Yellowstone National Park (YNP) for at least 11,000 years.2–5 Across these many years, humans have actively used, abused, and conserved the natural resources of the Northern Range. Human actions helped shape the vegetation and wildlife present on the Northern Range from prehistoric times to present day

The clinical- and cost-effectiveness of functional electrical stimulation and ankle-foot orthoses for foot drop in Multiple Sclerosis: a multicentre randomized trial

Objective: To compare the clinical- and cost-effectiveness of ankle-foot orthoses (AFOs) and functional electrical stimulation (FES) over 12 months in people with Multiple Sclerosis with foot drop. Design: Multicentre, powered, non-blinded, randomized trial. Setting: Seven Multiple Sclerosis outpatient centres across Scotland. Subjects: Eighty-five treatment-naïve people with Multiple Sclerosis with persistent (>three months) foot drop. Interventions: Participants randomized to receive a custom-made, AFO (n = 43) or FES device (n = 42). Outcome measures: Assessed at 0, 3, 6 and 12 months; 5-minute self-selected walk test (primary), Timed 25 Foot Walk, oxygen cost of walking, Multiple Sclerosis Impact Scale-29, Multiple Sclerosis Walking Scale-12, Modified Fatigue Impact Scale, Euroqol five-dimension five-level questionnaire, Activities-specific Balance and Confidence Scale, Psychological Impact of Assistive Devices Score, and equipment and National Health Service staff time costs of interventions. Results: Groups were similar for age (AFO, 51.4 (11.2); FES, 50.4(10.4) years) and baseline walking speed (AFO, 0.62 (0.21); FES 0.73 (0.27) m/s). In all, 38% dropped out by 12 months (AFO, n = 21; FES, n = 11). Both groups walked faster at 12 months with device (P < 0.001; AFO, 0.73 (0.24); FES, 0.79 (0.24) m/s) but no difference between groups. Significantly higher Psychological Impact of Assistive Devices Scores were found for FES for Competence (P = 0.016; AFO, 0.85(1.05); FES, 1.53(1.05)), Adaptability (P = 0.001; AFO, 0.38(0.97); FES 1.53 (0.98)) and Self-Esteem (P = 0.006; AFO, 0.45 (0.67); FES 1 (0.68)). Effects were comparable for other measures. FES may offer value for money alternative to usual care. Conclusion: AFOs and FES have comparable effects on walking performance and patient-reported outcomes; however, high drop-outs introduces uncertainty