792 research outputs found
Nonclassical Degrees of Freedom in the Riemann Hamiltonian
The Hilbert-Polya conjecture states that the imaginary parts of the zeros of
the Riemann zeta function are eigenvalues of a quantum hamiltonian. If so,
conjectures by Katz and Sarnak put this hamiltonian in Altland and Zirnbauer's
universality class C. This implies that the system must have a nonclassical
two-valued degree of freedom. In such a system, the dominant primitive periodic
orbits contribute to the density of states with a phase factor of -1. This
resolves a previously mysterious sign problem with the oscillatory
contributions to the density of the Riemann zeros.Comment: 4 pages, no figures; v3-6 have minor corrections to v2, v2 has a more
complete solution of the sign problem than v
V/STOL lift fan commercial short haul transports: Continuing conceptual design study
A design study of commercial V/STOL transport airplanes for a 1985 operational time period has been made. The baseline mission considered was 400 nmi at a cruise speed of M = 0.75 and a 100-passenger payload with VTOL. Variations from the baseline included mission distance, payload, cruise speed, and propulsion system failure philosophy. All designs used propulsion systems consisting of multiple gas generators driving remote tip turbine lift and lift/cruise fans. By considering the fan to be designed for operational reliability, significant simplication of the airplane systems and reduction in airplane size and cost can be achieved
Notes on the use and interpretation of radiostereometric analysis
ABSTRACT With increasing numbers of research groups carrying out radiostereometric analysis (RSA), it is important to reach a consensus on how the main aspects of the technique should be carried out and how the results should be presented in an appropriate and consistent way
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Coal liquefaction process streams characterization and evaluation. Novel analytical techniques for coal liquefaction: Fluorescence microscopy
This study demonstrated the feasibility of using fluorescence and reflectance microscopy techniques for the examination of distillation resid materials derived from direct coal liquefaction. Resid, as defined here, is the 850{degrees}F{sup +} portion of the process stream, and includes soluble organics, insoluble organics and ash. The technique can be used to determine the degree of hydrogenation and the presence of multiple phases occurring within a resid sample. It can also be used to infer resid reactivity. The technique is rapid, requiring less than one hour for sample preparation and examination, and thus has apparent usefulness for process monitoring. Additionally, the technique can distinguish differences in samples produced under various process conditions. It can, therefore, be considered a potentially useful technique for the process developer. Further development and application of this analytical method as a process development tool is justified based on these results
Application of the microhole and strip plate detector for neutron detection
We introduce the microhole and strip plate (MHSP) detector as a micropattern detector for the detection of thermal and epithermal neutrons. Detection sensitivity is obtained by filling these detectors with 3He at high pressures. We propose the use of argon-xenon penning mixtures as the stopping gas as opposed to the usual carbon based stopping gases. These argon-xenon mixtures provide suitable gas gains for the high pressure/high resolution neutron detector applications. With these mixtures it is possible to obtain a sealed detector with only rare-gas filling which is simple to purify and not subject to ageing. An MHSP gas detector filled with a 3-bar argon/50-mbar xenon/6-bar helium mixture can achieve gains above 2×103. This mixture allows neutron detection efficiencies of about 70% at 1 Å for a 2.5-cm thick absorption region and intrinsic position resolution (full-width at half-maximum) of about 1.8 mm. The sensitivity to γ-rays of the present mixture will be the same when compared to that of 2.6-bar CF
Proton endor study of the photoexcited triplet state PT in Rps. sphaeroides R-26 photosynthetic reaction centres
The photoexcited triplet state PT of Rhodopseudomonas sphaeroides R-26 has been investigated by ENDOR measurements performed on frozen photosynthetic reaction centre solutions. For the first time hyperfine data could be obtained for PT. These data indicate a delocalisation of the triplet state over two bacteriochlorophyll a molecules
Revisiting the Local Scaling Hypothesis in Stably Stratified Atmospheric Boundary Layer Turbulence: an Integration of Field and Laboratory Measurements with Large-eddy Simulations
The `local scaling' hypothesis, first introduced by Nieuwstadt two decades
ago, describes the turbulence structure of stable boundary layers in a very
succinct way and is an integral part of numerous local closure-based numerical
weather prediction models. However, the validity of this hypothesis under very
stable conditions is a subject of on-going debate. In this work, we attempt to
address this controversial issue by performing extensive analyses of turbulence
data from several field campaigns, wind-tunnel experiments and large-eddy
simulations. Wide range of stabilities, diverse field conditions and a
comprehensive set of turbulence statistics make this study distinct
Near-Field Pressure Signature Splicing for Low-Fidelity Design Space Exploration of Supersonic Aircraft
As interest in supersonic overland flight intensifies, new ways to meet government restrictions on sonic boom loudness must be implemented. Low-fidelity aerodynamic tools, such as PANAIR, can estimate the near-field pressure signature that ultimately determines the loudness of the sonic boom at the ground. These tools can greatly benefit the exploration of large design spaces due to their computational efficiency. One of the limitations of low-fidelity tools is the accuracy of the solution produced, which is dependent on the fundamental physical assumptions made in the development of the governing equations. If flow patterns are produced that severely violate these fundamental assumptions, the validity of the near-field pressure signature is compromised. A method is proposed that splices together near-field pressure signatures from a low-fidelity and a higher-fidelity tool by cutting each pressure signature at a critical point and then blending the low-fidelity signature into the higher-fidelity signature. By splicing the signatures together, sections of the low-fidelity signature that represent fundamental violations of the governing equation are removed. This method allows for the exploration of the design space corresponding to areas on the geometry that produce accurate results in a low-fidelity signature. The method is tested on the JAXA Wing Body geometry from the Second AIAA Sonic Boom Prediction Workshop and shows that perturbations to this geometry can produce loudness results that match the high-fidelity results to within 0.4 PLdB
Intervention planning and modification of the BUMP intervention: a digital intervention for the early detection of raised blood pressure in pregnancy
Background: Hypertensive disorders in pregnancy, particularly pre-eclampsia, pose a substantial health risk for both maternal and foetal outcomes. The BUMP (Blood Pressure Self-Monitoring in Pregnancy) interventions are being tested in a trial. They aim to facilitate the early detection of raised blood pressure through self-monitoring. This article outlines how the self-monitoring interventions in the BUMP trial were developed and modified using the person-based approach to promote engagement and adherence.
Methods: Key behavioural challenges associated with blood pressure self-monitoring in pregnancy were identified through synthesising qualitative pilot data and existing evidence, which informed guiding principles for the development process. Social cognitive theory was identified as an appropriate theoretical framework. A testable logic model was developed to illustrate the hypothesised processes of change associated with the intervention. Iterative qualitative feedback from women and staff informed modifications to the participant materials.
Results: The evidence synthesis suggested women face challenges integrating self-monitoring into their lives and that adherence is challenging at certain time points in pregnancy (for example, starting maternity leave). Intervention modification included strategies to address adherence but also focussed on modifying outcome expectancies, by providing messages explaining pre-eclampsia and outlining the potential benefits of self-monitoring.
Conclusions: With an in-depth understanding of the target population, several methods and approaches to plan and develop interventions specifically relevant to pregnant women were successfully integrated, to address barriers to behaviour change while ensuring they are easy to engage with, persuasive and acceptable
Scaling-up Health-Arts Programmes: the largest study in the world bringing arts-based mental health interventions into a national health service
The Scaling-up Health-Arts Programme: Implementation and
Effectiveness Research (SHAPER) project is the world’s largest hybrid study on the
impact of the arts on mental health embedded into a national healthcare system. This
programme, funded by the Wellcome Trust, aims to study the impact and the
scalability of the arts as an intervention for mental health. The programme will be
delivered by a team of clinicians, research scientists, charities, artists, patients and
healthcare professionals in the UK’s National Health Service (NHS) and the
community, spanning academia, the NHS and the charity sector. SHAPER consists of
three studies – Melodies for Mums, Dance for Parkinson’s, and Stroke Odysseys –
which will recruit over 800 participants, deliver the interventions and draw
conclusions on their clinical impact, implementation effectiveness and costeffectiveness. We hope that this work will inspire organisations and commissioners
in the NHS and around the world to expand the remit of social prescribing to include
evidence-based arts interventions
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