Magnetic field tuning of coplanar waveguide resonators

We describe measurements on microwave coplanar resonators designed for quantum bit experiments. Resonators have been patterned onto sapphire and silicon substrates, and quality factors in excess of a million have been observed. The resonant frequency shows a high sensitivity to magnetic field applied perpendicular to the plane of the film, with a quadratic dependence for the fundamental, second and third harmonics. Frequency shift of hundreds of linewidths can be obtained.Comment: Accepted for publication in AP

On the properties of superconducting planar resonators at mK temperatures

Planar superconducting resonators are now being increasingly used at mK temperatures in a number of novel applications. They are also interesting devices in their own right since they allow us to probe the properties of both the superconductor and its environment. We have experimentally investigated three types of niobium resonators - including a lumped element design - fabricated on sapphire and SiO_2/Si substrates. They all exhibit a non-trivial temperature dependence of their centre frequency and quality factor. Our results shed new light on the interaction between the electromagnetic waves in the resonator and two-level fluctuators in the substrate.Comment: V2 includes some minor corrections/changes. Submitted to PR

A Statistical Description of AGN Jet Evolution from the VLBA Imaging and Polarimetry Survey (VIPS)

A detailed analysis of the evolution of the properties of core-jet systems within the VLBA Imaging and Polarimetry Survey (VIPS) is presented. We find a power-law relationship between jet intensity and width that suggests for the typical jet, little if any energy is lost as it moves away from its core. Using VLA images at 1.5 GHz, we have found evidence that parsec-scale jets tend to be aligned with the the direction of emission on kiloparsec scales. We also found that this alignment improves as the jets move farther from their cores on projected scales as small as ~50-100 pc. This suggests that realignment of jets on these projected scales is relatively common. We typically find a modest amount of bending (a change in jet position angle of ~5 deg.) on these scales, suggesting that this realignment may typically occur relatively gradually.Comment: Accepted to ApJ, 20 pages, 8 figure

Characteristics of Gamma-Ray Loud Blazars in the VLBA Imaging and Polarimetry Survey

The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed as part of the VLBA Imaging and Polarimetry Survey (VIPS). This large, flux-limited sample of active galactic nuclei (AGN) provides insights into the mechanism that produces strong gamma-ray emission. At lower flux levels, radio flux density does not directly correlate with gamma-ray flux. We find that the LAT-detected BL Lacs tend to be similar to the non-LAT BL Lacs, but that the LAT-detected FSRQs are often significantly different from the non-LAT FSRQs. The differences between the gamma-ray loud and quiet FSRQs can be explained by Doppler boosting; these objects appear to require larger Doppler factors than those of the BL Lacs. It is possible that the gamma-ray loud FSRQs are fundamentally different from the gamma-ray quiet FSRQs. Strong polarization at the base of the jet appears to be a signature for gamma-ray loud AGN.Comment: 32 pages, 9 figures, accepted by Ap

J16021+3326: New Multi-Frequency Observations of a Complex Source

We present multifrequency Very Long Baseline Array (VLBA) observations of J16021+3326. These observations, along with variability data obtained from the Owens Valley Radio Observatory (OVRO) candidate gamma-ray blazar monitoring program, clearly indicate this source is a blazar. The peculiar characteristic of this blazar, which daunted previous classification attempts, is that we appear to be observing down a precessing jet, the mean orientation of which is aligned with us almost exactly.Comment: 16 pages, 7 Figures, 2 Tables, accepted to Ap

Circuit QED with a Flux Qubit Strongly Coupled to a Coplanar Transmission Line Resonator

We propose a scheme for circuit quantum electrodynamics with a superconducting flux-qubit coupled to a high-Q coplanar resonator. Assuming realistic circuit parameters we predict that it is possible to reach the strong coupling regime. Routes to metrological applications, such as single photon generation and quantum non-demolition measurements are discussed.Comment: 8 pages, 5 figure

LONTalk as a Standard Protocol For Underwater Sensor Platforms

Proceedings IEEE, Oceans 97, Halifax, Oct. 1997 IEEE CD-ROM 0-7803-4111-

Peer support for discharge from inpatient to community mental health services: Study protocol clinical trial (SPIRIT Compliant).

INTRODUCTION: In the period shortly after discharge from inpatient to community mental health care, people are at increased risk of self-harm, suicide, and readmission to hospital. Discharge interventions including peer support have shown potential, and there is some evidence that community-based peer support reduces readmissions. However, systematic reviews of peer support in mental health services indicate poor trial quality and a lack of reporting of how peer support is distinctive from other mental health support. This study is designed to establish the clinical and cost effectiveness of a peer worker intervention to support discharge from inpatient to community mental health care, and to address issues of trial quality and clarity of reporting of peer support interventions. METHODS: This protocol describes an individually randomized controlled superiority trial, hypothesizing that people offered a peer worker discharge intervention in addition to usual follow-up care in the community are less likely to be readmitted in the 12 months post discharge than people receiving usual care alone. A total of 590 people will be recruited shortly before discharge from hospital and randomly allocated to care as usual plus the peer worker intervention or care as usual alone. Manualized peer support provided by trained peer workers begins in hospital and continues for 4 months in the community post discharge. Secondary psychosocial outcomes are assessed at 4 months post discharge, and service use and cost outcomes at 12 months post discharge, alongside a mixed methods process evaluation. DISCUSSION: Clearly specified procedures for sequencing participant allocation and for blinding assessors to allocation, plus full reporting of outcomes, should reduce risk of bias in trial findings and contribute to improved quality in the peer support evidence base. The involvement of members of the study team with direct experience of peer support, mental distress, and using mental health services, in coproducing the intervention and designing the trial, ensures that we theorize and clearly describe the peer worker intervention, and evaluate how peer support is related to any change in outcome. This is an important methodological contribution to the evidence base. TRIAL REGISTRATION: This study was prospectively registered as ISRCTN 10043328 on November 28, 2016