Research and development of superconducting thin films Final report, 15 Dec. 1965 - 15 Dec. 1966

Superconducting niobium thin film productio

High Mass Triple Systems: The Classical Cepheid Y Car

We have obtained an HST STIS ultraviolet high dispersion Echelle mode spectrum the binary companion of the double mode classical Cepheid Y Car. The velocity measured for the hot companion from this spectrum is very different from reasonable predictions for binary motion, implying that the companion is itself a short period binary. The measured velocity changed by 7 km/ s during the 4 days between two segments of the observation confirming this interpretation. We summarize "binary" Cepheids which are in fact members of triple system and find at least 44% are triples. The summary of information on Cepheids with orbits makes it likely that the fraction is under-estimated.Comment: accepted by A

Polaris the Cepheid returns: 4.5 years of monitoring from ground and space

We present the analysis of 4.5 years of nearly continuous observations of the classical Cepheid Polaris, which comprise the most precise data available for this star. We have made spectroscopic measurements from ground and photometric measurements from the WIRE star tracker and the SMEI instrument on the Coriolis satellite. Measurements of the amplitude of the dominant oscillation (P = 4 days), that go back more than a century, show a decrease from 120 mmag to 30 mmag (V magnitude) around the turn of the millennium. It has been speculated that the reason for the decrease in amplitude is the evolution of Polaris towards the edge of the instability strip. However, our new data reveal an increase in the amplitude by about 30% from 2003-2006. It now appears that the amplitude change is cyclic rather than monotonic, and most likely the result of a pulsation phenomenon. In addition, previous radial velocity campaigns have claimed the detection of long-period variation in Polaris (P > 40 days). Our radial velocity data are more precise than previous datasets, and we find no evidence for additional variation for periods in the range 3-50 days with an upper limit of 100 m/s. However, in the WIRE data we find evidence of variation on time-scales of 2-6 days, which we interpret as being due to granulation.Comment: Accepted by ApJ. 8 pages. Quality of figures 1+3+7 degrade

Hubble Space Telescope WFPC-2 Imaging of Cassiopeia A

The young SNR Cassiopeia A was imaged with WFPC-2 through four filters selected to capture the complete velocity range of the remnant's main shell in several important emission lines. Primary lines detected were [O III] 4959,5007, [N II] 6583, [S II] 6716,6731 + [O II] 7319,7330 + [O I] 6300,6364, and [S III] 9069,9532. About 3/4th of the remnant's main shell was imaged in all four filters. Considerable detail is observed in the reverse-shocked ejecta with typical knot scale lengths of 0.2"-0.4" (1 - 2 x 10^16 cm). Both bright and faint emission features appear highly clumped. Large differences in [S III] and [O III] line intensities indicating chemical abundance differences are also seen, particularly in knots located along the bright northern limb and near the base of the northeast jet. A line of curved overlapping filament in the remnant's northwestern rim appears to mark the location of the remnant's reverse shock front in this region. Finger-like ejecta structures elsewhere suggest cases where the reverse shock front is encountering the remnant's clumped ejecta. Narrow-band [N II] images of the remnant's circumstellar knots ("QSFs") reveal them to be 0.1"-0.6" thick knots and filaments, often with diffuse edges facing away from the center of expansion. Three color composite images of the whole remnant and certain sections along with individual filter enlargements of selected regions of the bright optical shell are presented and discussed.Comment: 26 pages, 12 figures Accepted to the Astronomical Journa

The radius and effective temperature of the binary Ap star beta CrB from CHARA/FLUOR and VLT/NACO observations

The prospects for using asteroseismology of rapidly oscillating Ap (roAp) stars are hampered by the large uncertainty in fundamental stellar parameters. Results in the literature for the effective temperature (Teff) often span a range of 1000 K. Our goal is to reduce systematic errors and improve the Teff calibration of Ap stars based on new interferometric measurements. We obtained long-baseline interferometric observations of beta CrB using the CHARA/FLUOR instrument. To disentangle the flux contributions of the two components of this binary star, we obtained VLT/NACO adaptive optics images. We determined limb darkened angular diameters of 0.699+-0.017 mas for beta CrB A (from interferometry) and 0.415+-0.017 mas for beta CrB B (from surface brightness- color relations), corresponding to radii of 2.63+-0.09 Rsun (3.4 percent uncertainty) and 1.56+-0.07 Rsun (4.5 percent). The combined bolometric flux of the A and B components was determined from satellite UV data, spectrophotometry in the visible and broadband data in the infrared. The flux from the B component constitutes 16+-4 percent of the total flux and was determined by fitting an ATLAS9 model atmosphere to the broad-band NACO J and K magnitudes. Combining the flux of the A component with its measured angular diameter, we determine the effective temperature Teff(A) = 7980+-180 K (2.3 percent). Our new interferometric and imaging data enable a nearly model-independent determination of the effective temperature of beta CrB A. Including our recent study of alpha Cir, we now have direct Teff measurements of two of the brightest roAp stars, providing a strong benchmark for an improved calibration of the Teff scale for Ap stars. This will support the use of potentially strong constraints imposed by asteroseismic studies of roAp stars.Comment: 7 pages, accepted by A&

Vortex Structure Around a Magnetic Dot in Planar Superconductors

The problem of the giant vortex state around a magnetic dot which is embedded in a superconducting film is investigated. The full non-linear, self-consistent Ginzburg-Landau equations are solved numerically in order to calculate the free energy, the order parameter of the host superconductor, the internal magnetic field due to the supercurrents, the corresponding current density, the magnetization probed in the vicinity of the dot, and the normal electron density as a function of the various parameters of the system. We find that, as we increase the magnetic moment of the dot, higher flux quanta vortex states become energetically more favorable, as they can better compete with the external magnetic field via the Meissner effect. In addition to that, they progressively become closer to each other in energy with direct experimental consequences, i.e. physical quantities like magnetization may fluctuate when measured, for example, as a function of a uniform external magnetic field.Comment: text 21 pages (REVTEX), 8 figures available upon reques

Moderate Antiproteinuric Effect of Add-On Aldosterone Blockade with Eplerenone in Non-Diabetic Chronic Kidney Disease. A Randomized Cross-Over Study

Reduction of proteinuria and blood pressure (BP) with blockers of the renin-angiotensin system (RAS) impairs the progression of chronic kidney disease (CKD). The aldosterone antagonist spironolactone has an antiproteinuric effect, but its use is limited by side effects. The present study evaluated the short-term antiproteinuric effect and safety of the selective aldosterone antagonist eplerenone in non-diabetic CKD.Open randomized cross-over trial.Forty patients with non-diabetic CKD and urinary albumin excretion greater than 300 mg/24 hours.Eight weeks of once-daily administration of add-on 25–50 mg eplerenone to stable standard antihypertensive treatment including RAS-blockade.24 hour urinary albumin excretion, BP, p-potassium, and creatinine clearance.The mean urinary albumin excretion was 22% [CI: 14,28], P<0.001, lower during treatment with eplerenone. Mean systolic BP was 4 mmHg [CI: 2,6], P = 0.002, diastolic BP was 2 mmHg [CI: 0,4], P = 0.02, creatinine clearance was 5% [CI: 2,8], P = 0.005, lower during eplerenone treatment. After correction for BP and creatinine clearance differences between the study periods, the mean urinary albumin excretion was 14% [CI: 4,24], P = 0.008 lower during treatment. Mean p-potassium was 0.1 mEq/L [CI: 0.1,0.2] higher during eplerenone treatment, P<0.001. Eplerenone was thus well tolerated and no patients were withdrawn due to hyperkalaemia.Open label, no wash-out period and a moderate sample size.In non-diabetic CKD patients, the addition of eplerenone to standard antihypertensive treatment including RAS-blockade caused a moderate BP independent fall in albuminuria, a minor fall in creatinine clearance and a 0.1 mEq/L increase in p-potassium

Muscle weakness and lack of reflex gain adaptation predominate during post-stroke posture control of the wrist

Instead of hyper-reflexia as sole paradigm, post-stroke movement disorders are currently considered the result of a complex interplay between neuronal and muscular properties, modified by level of activity. We used a closed loop system identification technique to quantify individual contributors to wrist joint stiffness during an active posture task. Continuous random torque perturbations applied to the wrist joint by a haptic manipulator had to be resisted maximally. Reflex provoking conditions were applied i.e. additional viscous loads and reduced perturbation signal bandwidth. Linear system identification and neuromuscular modeling were used to separate joint stiffness into the intrinsic resistance of the muscles including co-contraction and the reflex mediated contribution. Compared to an age and sex matched control group, patients showed an overall 50% drop in intrinsic elasticity while their reflexive contribution did not respond to provoking conditions. Patients showed an increased mechanical stability compared to control subjects. Post stroke, we found active posture tasking to be dominated by: 1) muscle weakness and 2) lack of reflex adaptation. This adds to existing doubts on reflex blocking therapy as the sole paradigm to improve active task performance and draws attention to muscle strength and power recovery and the role of the inability to modulate reflexes in post stroke movement disorders.Mechanical, Maritime and Materials Engineerin

Prognostic factors for response to treatment by corticosteroid injection or surgery in carpal tunnel syndrome (PaLMS study): a prospective multi‐centre cohort study

Introduction: Studies of prognosis for surgery and corticosteroid injection for carpal tunnel syndrome have considered only a limited range of explanatory variables for outcome. Methods: Data were prospectively collected on patient‐reported symptoms, physical and psychological functioning, comorbidity and quality of life at baseline and 6 monthly for up to 2 years. Outcomes were patient‐rated change over a 6‐month period and symptom‐severity score at 18 months. Results: 754 patients with CTS completed baseline questionnaires and 626 (83%) completed follow‐up to 18 months. Multivariable modelling identified, independent of symptom severity at outset, higher health utility, fewer comorbidities and lower anxiety as significant predictors of better outcome from surgery. In patients treated by steroid injection, independent of symptom severity at outset, shorter duration of symptoms and having no prior injection were significant predictors of better outcome. Discussion: These multivariable models of outcome may inform shared decision‐making about treatment for CTS