Dynamical error bounds for continuum discretisation via Gauss quadrature rules, -- a Lieb-Robinson bound approach

Instances of discrete quantum systems coupled to a continuum of oscillators are ubiquitous in physics. Often the continua are approximated by a discrete set of modes. We derive analytical error bounds on expectation values of system observables that have been time evolved under such discretised Hamiltonians. These bounds take on the form of a function of time and the number of discrete modes, where the discrete modes are chosen according to Gauss quadrature rules. The derivation makes use of tools from the field of Lieb-Robinson bounds and the theory of orthonormal polynominals.Comment: 12 pages + 14 pages of proofs and appendices, Journal of Mathematical Physics, Vol.57, Issue 2 (2016) http://scitation.aip.org/content/aip/journal/jmp/57/2/10.1063/1.494043

A time dependent relation between EUV solar flare light-curves from lines with differing formation temperatures

Extreme ultraviolet (EUV) solar flare emissions evolve in time as the emitting plasma heats and then cools. Although accurately modeling this evolution has been historically difficult, especially for empirical relationships, it is important for understanding processes at the Sun, as well as for their influence on planetary atmospheres. With a goal to improve empirical flare models, a new simple empirical expression is derived to predict how cool emissions will evolve based on the evolution of a hotter emission. This technique is initially developed by studying 12 flares in detail observed by the EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory (SDO). Then, over 1100 flares observed by EVE are analyzed to validate these relationships. The Cargill and Enthalpy Based Thermal Evolution of Loops (EBTEL) flare cooling models are used to show that this empirical relationship implies the energy radiated by a population of hotter formed ions is approximately proportional to the energy exciting a population of cooler formed ions emitting when the peak formation temperatures of the two lines are up to 72% of each other and above 2 MK. These results have practical implications for improving flare irradiance empirical modeling and for identifying key emission lines for future monitoring of flares for space weather operations; and also provide insight into the cooling processes of flare plasma.Comment: Final version accepted for publication by the Journal of Space Weather and Space Climate on 23 November 201

Probing the birth of fast rotating magnetars through high-energy neutrinos

We investigate the high-energy neutrino emission expected from newly born magnetars surrounded by their stellar ejecta. Protons might be accelerated up to 0.1-100 EeV energies possibly by, e.g., the wave dissipation in the winds, leading to hadronic interactions in the stellar ejecta. The resulting PeV-EeV neutrinos can be detected by IceCube/KM3Net with a typical peak time scale of a few days after the birth of magnetars, making the characteristic soft-hard-soft behavior. Detections would be important as a clue to the formation mechanism of magnetars, although there are ambiguities coming from uncertainties of several parameters such as velocity of the ejecta. Non-detections would also lead to useful constraints on the scenario.Comment: 5 pages, 3 figures, accepted for publication in PR

Rotationsal and vibrational spectra of molecular ions: Feasibility of laboratory and astrophysical observation

The rotational spectra of a number of small molecular ions should be detectable in the microwave or millimeter wave regions in laboratory experiments using currently available techniques. The dipole moments and absorption coefficients of polar diatomics CO(+) and NO(+) as well as asymmetric isotopically enriched species, like O-18O-16(+), NE-20NE-22(+), and OC-18 O-16(+) are calculated to be sufficiently large to allow observation of their spectra. In addition to the detailed molecular structure information which such spectral data would provide, precise knowledge of the transition frequencies would render likely the detection of certain of these ions in the interstellar sources or in planetary atmospheres. All of these ions also possess vibrational spectra which should be detectable in the infrared region in laboratory or astrophysical sources

Older adults and withdrawal from benzodiazepine hypnotics in general practice: effects on cognitive function, sleep, mood and quality of life

Background: Older adults are the main recipients of repeat prescriptions for benzodiazepine (BZD) hypnotics. BZDs can impair cognitive function and may not aid sleep when taken continuously for years. This study therefore aimed to determine if withdrawing from BZDs leads to changes in patients' cognitive function, quality of life, mood and sleep. Method: One hundred and ninety-two long-term users of BZD hypnotics, aged [gt-or-equal, slanted]65 years, were identified in 25 general practices. One hundred and four who wished to withdraw were randomly allocated to one of two groups under double-blind, placebo controlled conditions: group A's BZD dose was tapered from week 1 of the trial; group B were given their usual dose for 12 weeks and then it was tapered. An additional group (C) of 35 patients who did not wish to withdraw from BZDs participated as ‘continuers’. All patients were assessed at 0, 12 and 24 weeks and 50% were re-assessed at 52 weeks. Results: Sixty per cent of patients had taken BZDs continuously for >10 years; 27% for >20 years. Of all patients beginning the trial, 80% had successfully withdrawn 6 months later. There was little difference between groups A and B, but these groups differed from continuers (C) in that the performance of the withdrawers on several cognitive/psychomotor tasks showed relative improvements at 24 or 52 weeks. Withdrawers and continuers did not differ in sleep or BZD withdrawal symptoms. Conclusions: These results have clear implications for clinical practice. Withdrawal from BZDs produces some subtle cognitive advantages for older people, yet little in the way of withdrawal symptoms or emergent sleep difficulties. These findings also suggest that, taken long-term, BZDs do not aid sleep

A History of Fort Larned

This thesis is a study of the history of Fort Larned Kansas covering the years 1859-1932