Quantum gate characterization in an extended Hilbert space

We describe an approach for characterizing the process of quantum gates using quantum process tomography, by first modeling them in an extended Hilbert space, which includes non-qubit degrees of freedom. To prevent unphysical processes from being predicted, present quantum process tomography procedures incorporate mathematical constraints, which make no assumptions as to the actual physical nature of the system being described. By contrast, the procedure presented here ensures physicality by placing physical constraints on the nature of quantum processes. This allows quantum process tomography to be performed using a smaller experimental data set, and produces parameters with a direct physical interpretation. The approach is demonstrated by example of mode-matching in an all-optical controlled-NOT gate. The techniques described are non-specific and could be applied to other optical circuits or quantum computing architectures.Comment: 4 pages, 2 figures, REVTeX (published version

Prevalence of treatment-resistant hypertension after considering pseudo-resistance and morbidity: a cross-sectional study in Irish primary care

peer-reviewedBackground To confirm treatment-resistant hypertension (TRH), ambulatory blood pressure measurement (ABPM) must exclude white-coat hypertension (WCH), three or more medications should be prescribed at the optimal doses tolerated, and non-adherence and lifestyle should be examined. Most previous studies have not adequately considered pseudo-resistance and merely provide an apparent TRH (aTRH) prevalence figure. Aim To conduct a cross-sectional study of the prevalence of aTRH in general practice, and then consider pseudo-resistance and morbidity. Design and setting With support, 16 practices ran an anatomical therapeutic chemical (ATC) drug search, identifying patients on any possible hypertensive medications, and then a search of individual patients' electronic records took place. Method ABPM was used to rule out WCH. The World Health Organization-defined daily dosing guidelines determined adequate dosing. Adherence was defined as whether patients requested nine or more repeat monthly prescriptions within the past year. Results Sixteen practices participated (n = 50 172), and 646 patients had aTRH. Dosing was adequate in 19% of patients, 84% were adherent to medications, as defined by prescription refill, and 43% had ever had an ABPM. Using a BP cut-off of 140/90 mmHg, the prevalence of aTRH was 9% (95% confidence interval [CI] = 9.0 to 10.0). Consideration of pseudo-resistance further reduced prevalence rates to 3% (95% CI = 3.0 to 4.0). Conclusion Reviewing individual patient records results in a lower estimate of prevalence of TRH than has been previously reported. Further consideration for individual patients of pseudo-resistance additionally lowers these estimates, and may be all that is required for management in the vast majority of cases.PUBLISHEDpeer-reviewe

High-power single transverse and polarization mode VCSEL for silicon photonics integration

\ua9 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement. We demonstrate a 6.5 mW single transverse and polarization mode GaAs-based oxide-confined VCSEL at 850 nm. High power is enabled by a relatively large oxide aperture and an epitaxial design for low resistance, low optical loss, and high slope efficiency VCSELs. With the oxide aperture supporting multiple polarization unrestrained transverse modes, single transverse and polarization mode operation is achieved by a transverse and polarization mode filter etched into the surface of the VCSEL. While the VCSEL is specifically designed for light source integration on a silicon photonic integrated circuit, its performance in terms of power, spectral purity, polarization, and beam properties are of great interest for a large range of applications

Swift Observations of GRB 050603: An afterglow with a steep late time decay slope

We report the results of Swift observations of the Gamma Ray Burst GRB 050603. With a V magnitude V=18.2 about 10 hours after the burst the optical afterglow was the brightest so far detected by Swift and one of the brightest optical afterglows ever seen. The Burst Alert Telescope (BAT) light curves show three fast-rise-exponential-decay spikes with $T_{90}$=12s and a fluence of 7.6$\times 10^{-6}$ ergs cm$^{-2}$ in the 15-150 keV band. With an $E_{\rm \gamma, iso} = 1.26 \times 10^{54}$ ergs it was also one of the most energetic bursts of all times. The Swift spacecraft began observing of the afterglow with the narrow-field instruments about 10 hours after the detection of the burst. The burst was bright enough to be detected by the Swift UV/Optical telescope (UVOT) for almost 3 days and by the X-ray Telescope (XRT) for a week after the burst. The X-ray light curve shows a rapidly fading afterglow with a decay index $\alpha$=1.76$^{+0.15}_{-0.07}$. The X-ray energy spectral index was $\beta_{\rm X}$=0.71\plm0.10 with the column density in agreement with the Galactic value. The spectral analysis does not show an obvious change in the X-ray spectral slope over time. The optical UVOT light curve decays with a slope of $\alpha$=1.8\plm0.2. The steepness and the similarity of the optical and X-ray decay rates suggest that the afterglow was observed after the jet break. We estimate a jet opening angle of about 1-2$^{\circ}$Comment: 14 pages, accepted for publication in Ap

Transformation in a changing climate: a research agenda

The concept of transformation in relation to climate and other global change is increasingly receiving attention. The concept provides important opportunities to help examine how rapid and fundamental change to address contemporary global challenges can be facilitated. This paper contributes to discussions about transformation by providing a social science, arts and humanities perspective to open up discussion and set out a research agenda about what it means to transform and the dimensions, limitations and possibilities for transformation. Key focal areas include: (1) change theories, (2) knowing whether transformation has occurred or is occurring; (3) knowledge production and use; (4), governance; (5) how dimensions of social justice inform transformation; (6) the limits of human nature; (7) the role of the utopian impulse; (8) working with the present to create new futures; and (9) human consciousness. In addition to presenting a set of research questions around these themes the paper highlights that much deeper engagement with complex social processes is required; that there are vast opportunities for social science, humanities and the arts to engage more directly with the climate challenge; that there is a need for a massive upscaling of efforts to understand and shape desired forms of change; and that, in addition to helping answer important questions about how to facilitate change, a key role of the social sciences, humanities and the arts in addressing climate change is to critique current societal patterns and to open up new thinking. Through such critique and by being more explicit about what is meant by transformation, greater opportunities will be provided for opening up a dialogue about change, possible futures and about what it means to re-shape the way in which people live

Galactic populations of radio and gamma-ray pulsars in the polar cap model

We simulate the characteristics of the Galactic population of radio and $\gamma$-ray pulsars using Monte Carlo techniques. At birth, neutron stars are spatially distributed in the Galactic disk, with supernova-kick velocities, and randomly dispersed in age back to $10^9$ years. They are evolved in the Galactic gravitational potential to the present time. From a radio luminosity model, the radio flux is filtered through a selected set of radio-survey parameters. $\gamma$-ray luminosities are assigned using the features of recent polar cap acceleration models invoking space-charge-limited flow, and a pulsar death valley further attenuates the population of radio-loud pulsars. Assuming a simple emission geometry with aligned radio and $\gamma$-ray beams of 1 steradian solid angle, our model predicts that EGRET should have seen 7 radio-loud and 1 radio-quiet, $\gamma$-ray pulsars. With much improved sensitivity, GLAST, on the other hand, is expected to observe 76 radio-loud and 74 radio-quiet, $\gamma$-ray pulsars of which 7 would be identified as pulsed sources. We also explore the effect of magnetic field decay on the characteristics of the radio and $\gamma$-ray pulsar populations. Including magnetic field decay on a timescale of 5 Myr improves agreement with the radio pulsar population and increases the predicted number of GLAST detected pulsars to 90 radio-loud and 101 radio-quiet (9 pulsed) $\gamma$-ray pulsars. The lower flux threshold allows GLAST to detect $\gamma$-ray pulsars at larger distances than those observed by the radio surveys used in this study.Comment: 38 pages, 11 figures, accepted for publication v565 n1 Ap

Perinatal outcomes after admission with COVID-19 in pregnancy:a UK national cohort study

There are few population-based studies of sufficient size and follow-up duration to have reliably assessed perinatal outcomes for pregnant women hospitalised with SARS-CoV-2 infection. The United Kingdom Obstetric Surveillance System (UKOSS) covers all 194 consultant-led UK maternity units and included all pregnant women admitted to hospital with an ongoing SARS-CoV-2 infection. Here we show that in this large national cohort comprising two years’ active surveillance over four SARS-CoV-2 variant periods and with near complete follow-up of pregnancy outcomes for 16,627 included women, severe perinatal outcomes were more common in women with moderate to severe COVID-19, during the delta dominant period and among unvaccinated women. We provide strong evidence to recommend continuous surveillance of pregnancy outcomes in future pandemics and to continue to recommend SARS-CoV-2 vaccination in pregnancy to protect both mothers and babies

The development of children’s early memory skills

A multi-task battery tapping nonverbal memory and language skills was used to assess 60 children at 18, 24, and 30 months. Analyses focused on the degree to which language, working memory, and deliberate memory skills were linked concurrently to children’s Elicited Imitation performance, and whether the patterns of association varied across the different ages. Language ability emerged as a predictor of immediate Elicited Imitation performance by 24 months and predicted delayed performance at each age. In addition to the contributions of language, the children’s abilities to search for and retrieve toys in the deliberate memory task were associated with their immediate Elicited Imitation performance at each age. In addition to language, working memory was positively associated with aspects of both immediate and delayed performance at all ages. The extent to which it was possible to replicate and extend previous cross-sectional work in this longitudinal study is discussed

The use of nanovibration to discover specific and potent bioactive metabolites that stimulate osteogenic differentiation in mesenchymal stem cells

Bioactive metabolites have wide-ranging biological activities and are a potential source of future research and therapeutic tools. Here, we use nanovibrational stimulation to induce osteogenic differentiation of mesenchymal stem cells, in the absence of off-target, nonosteogenic differentiation. We show that this differentiation method, which does not rely on the addition of exogenous growth factors to culture media, provides an artifact-free approach to identifying bioactive metabolites that specifically and potently induce osteogenesis. We first identify a highly specific metabolite, cholesterol sulfate, an endogenous steroid. Next, a screen of other small molecules with a similar steroid scaffold identified fludrocortisone acetate with both specific and highly potent osteogenic-inducing activity. Further, we implicate cytoskeletal contractility as a measure of osteogenic potency and cell stiffness as a measure of specificity. These findings demonstrate that physical principles can be used to identify bioactive metabolites and then enable optimization of metabolite potency can be optimized by examining structure-function relationships