Constraints and Reality Conditions in the Ashtekar Formulation of General Relativity

We show how to treat the constraints and reality conditions in the $SO(3)$-ADM (Ashtekar) formulation of general relativity, for the case of a vacuum spacetime with a cosmological constant. We clarify the difference between the reality conditions on the metric and on the triad. Assuming the triad reality condition, we find a new variable, allowing us to solve the gauge constraint equations and the reality conditions simultaneously.Comment: LaTeX file, 12 pages, no figures; to appear in Classical and Quantum Gravit

Optical-fiber Preamplifiers for Ladar Detection and Associated Measurements for Improving the Signal-to-noise Ratio

In an effort to increase achievable postdetection signal-tonoise ratios (SNRs) of continuous-wave, 1-gm all-solid-state ladar systems, a prototype rare-earth-doped optical-fiber amplifier has been included in the optical return signal path of both a heterodyne and a directdetection ladar system. We provide numerical predictions for SNR increases according to our previously developed theory. We also detail our experimental efforts and provide the results of SNR measurements for four distinct cases: direct ladar detection with and without a fiber amplifier, and heterodyne ladar detection with and without a fiber amplifier. Experimentally measured increases in SNRs for ladar systems incorporating an optical-fiber amplifier are then compared with our earlier predictions. Specifically, we have found that for direct detection with a fiber amplifier in place, the predicted SNR increase is 42.0 dB, and we have measured an increase of 36.5 dB. Similarly, for heterodyne ladar detection with a fiber amplifier, the predicted SNR increase is 3.8 dB, and we have measured an increase of 8.0 dB

Sensitivity Improvement of a 1-μm Ladar System Incorporating an Active Optical Fiber Preamplifier

In an effort to increase the SNR of a continuous wave, 1-μm all solid state ladar system, a rare-earth-doped optical fiber amplifier is investigated as a preamplifier for ladar return signals. The experimental system is detailed and a theoretical analysis of the fiber amplifier\u27s effect on both heterodyne and direct detection schemes is provided. Beginning with the optical powers incident on the detector, the signal and noises are analyzed, through the detector electronics, to predict the SNR. The SNR is then plotted as a function of the return signal power, and a SNR threshold is defined to determine a minimum detectable signal power. The return signals required to attain the SNR threshold are then compared for four cases: direct detection with and without the fiber amplifier and heterodyne detection with and without the fiber amplifier. For the direct detection scheme considered, our results predict a sensitivity increase of 20.6 dB with the addition of the fiber amplifier, yet for heterodyne detection the predicted sensitivity increase is only 3.1 dB

The impact of co-located NHS walk-in centres on emergency departments

Objectives: To determine the impact of establishing walk-in centres alongside emergency departments on attendance rates, visit duration, process, costs and outcome of care. Methods: Eight hospitals with co-located emergency departments and walk-in centres were compared with eight matched emergency departments without walk-in centres. Site visits were conducted. Routine data about attendance numbers and use of resources were analysed. A random sample of records of patients attending before and after walk-in centres opened were also assessed. Patients who had not been admitted to hospital were sent a postal questionnaire. Results: In most sites, the walk-in centres did not have a distinct identity and there were few differences in the way services were provided compared with control sites. Overall, there was no evidence of an increase in attendance at sites with walk-in centres, but considerable variability across sites. The proportion of patients managed within the four-hour NHS target improved at sites both with and without walk-in centres. There was no evidence of any difference in re-consultation rates, costs of care or patient outcomes at sites with or without walk-in centres. Conclusions: Most hospitals in this study implemented the walk-in centre concept to a very limited extent. Consequently there was no evidence of any impact on attendance rates, process, costs or outcome of care

Comparing care at walk-in centres and at accident and emergency departments: an exploration of patient choice, preference and satisfaction

Objectives: To explore the impact of establishing walk-in centres alongside emergency departments on patient choice, preference and satisfaction. Methods: A controlled, mixed-method study comparing eight emergency departments with co-located walk-in centres with the same number of ‘traditional’ emergency departments. This paper focuses on the results of a cross-sectional questionnaire survey of users. Results: Survey data demonstrated that patients were frequently unable to distinguish between being treated at a walk-in centre or an A&E department, and even where this was the case, opportunities to exercise choice about their preferred care provider were often limited. Few made an active choice to attend a co-located walk-in centre. Patients attending walk-in centres were just as likely to be satisfied overall with the care they received as their counterparts who were treated in the co-located A&E facility, although a small proportion of walk-in centre users did report greater satisfaction with some specific aspects of their care and consultation. Conclusions: Whilst one of the key policy goals underpinning the co-location of walk-in centres next to an A&E department was to provide patients with more options for accessing healthcare and greater choice, leading in turn to increased satisfaction, this evaluation was able to provide little evidence to support this. The high percentage of patients expressing a preference for care in an established emergency department compared to a new walk-in centre facility raises questions for future policy development. Further consideration should therefore be given to the role that A&E focused walk-in centres play in the Department of Health’s current policy agenda, as far as patient choice is concerned

Health services changes: is a run-in period necessary before evaluation in randomised clinical trials?

Background Most randomised clinical trials (RCTs) testing a new health service do not allow a run-in period of consolidation before evaluating the new approach. Consequently, health professionals involved may feel insufficiently familiar or confident, or that new processes or systems that are integral to the service are insufficiently embedded in routine care prior to definitive evaluation in a RCT. This study aimed to determine the optimal run-in period for a new physiotherapy-led telephone assessment and treatment service known as PhysioDirect and whether a run-in was needed prior to evaluating outcomes in an RCT. Methods The PhysioDirect trial assessed whether PhysioDirect was as effective as usual care. Prior to the main trial, a run-in of up to 12 weeks was permitted to facilitate physiotherapists to become confident in delivering the new service. Outcomes collected from the run-in and main trial were length of telephone calls within the PhysioDirect service and patients’ physical function (SF-36v2 questionnaire) and Measure Yourself Medical Outcome Profile v2 collected at baseline and six months. Joinpoint regression determined how long it had taken call times to stabilise. Analysis of covariance determined whether patients’ physical function at six months changed from the run-in to the main trial. Results Mean PhysioDirect call times (minutes) were higher in the run-in (31 (SD: 12.6)) than in the main trial (25 (SD: 11.6)). Each physiotherapist needed to answer 42 (95% CI: 20,56) calls for their mean call time to stabilise at 25 minutes per call; this took a minimum of seven weeks. For patients’ physical function, PhysioDirect was equally clinically effective as usual care during both the run-in (0.17 (95% CI: -0.91,1.24)) and main trial (-0.01 (95% CI: -0.80,0.79)). Conclusions A run-in was not needed in a large trial testing PhysioDirect services in terms of patient outcomes. A learning curve was evident in the process measure of telephone call length. This decreased during the run-in and stabilised prior to commencement of the main trial. Future trials should build in a run-in if it is anticipated that learning would have an effect on patient outcome

Preparing for a Northwest Passage: A Workshop on the Role of New England in Navigating the New Arctic

Preparing for a Northwest Passage: A Workshop on the Role of New England in Navigating the New Arctic (March 25 - 27, 2018 -- The University of New Hampshire) paired two of NSF\u27s 10 Big Ideas: Navigating the New Arctic and Growing Convergence Research at NSF. During this event, participants assessed economic, environmental, and social impacts of Arctic change on New England and established convergence research initiatives to prepare for, adapt to, and respond to these effects. Shipping routes through an ice-free Northwest Passage in combination with modifications to ocean circulation and regional climate patterns linked to Arctic ice melt will affect trade, fisheries, tourism, coastal ecology, air and water quality, animal migration, and demographics not only in the Arctic but also in lower latitude coastal regions such as New England. With profound changes on the horizon, this is a critical opportunity for New England to prepare for uncertain yet inevitable economic and environmental impacts of Arctic change

A video life-world approach to consultation practice: The relevance of a socio-phenomenological approach

This article discusses the [development and] use of a video life-world schema to explore alternative orientations to the shared health consultation. It is anticipated that this schema can be used by practitioners and consumers alike to understand the dynamics of videoed health consultations, the role of the participants within it and the potential to consciously alter the outcome by altering behaviour during the process of interaction. The study examines health consultation participation and develops an interpretative method of analysis that includes image elicitation (via videos), phenomenology (to identify the components of the analytic framework), narrative (to depict the stories of interactions) and a reflexive mode (to develop shared meaning through a conceptual framework for analysis). The analytic framework is derived from a life-world conception of human mutual shared interaction which is presented here as a novel approach to understanding patient-centred care. The video materials used in this study were derived from consultations in a Walk-in Centre (WiC) in East London. The conceptual framework produced through the process of video analysis is comprised of different combinations of movement, knowledge and emotional conversations that are used to classify objective or engaged WiC health care interactions. The videoed interactions organise along an active or passive, facilitative or directive typical situation continuum illustrating different kinds of textual approaches to practice that are in tension or harmony. The schema demonstrates how practitioners and consumers interact to produce these outcomes and indicates the potential for both consumers and practitioners to be educated to develop practice dynamics that support patient-centred care and impact on health outcomes

Combining ERP and Structural MRI Information in First Episode Schizophrenia and Bipolar Disorder

The electrical activity in the electroencephalogram (EEG) and the event-related potentials extracted from the EEG provide the greatest temporal resolution for examining brain function. When coupled with the high spatial resolution of structural magnetic resonance imaging (sMRI), the combined techniques provide a powerful tool for neuroscience in the examination of brain abnormalities in major psychiatric illnesses. Over the last 20 years, our work has examined brain structure and function in schizophrenia. Both EEG and MRI measures have indicated profound abnormalities in schizophrenia within the temporal lobe, particularly marked over the left hemisphere. Our studies of patients first hospitalized due to psychosis revealed the early course of the disease to be characterized by progressive impairment and cortical gray matter reduction, most intense near the time of first hospitalization. Knowledge of those locations and brain signals affected early should help understand the basic physiological defect underlying this progression, with potential implications for new therapeutic interventions

Salinity from Space Unlocks Satellite-Based Assessment of Ocean Acidification

Approximately a quarter of the carbon dioxide (CO2) that we emit into the atmosphere is absorbed by the ocean. This oceanic uptake of CO2 leads to a change in marine carbonate chemistry resulting in a decrease of seawater pH and carbonate ion concentration, a process commonly called “Ocean Acidification”. Salinity data are key for assessing the marine carbonate system, and new space-based salinity measurements will enable the development of novel space-based ocean acidification assess- ment. Recent studies have highlighted the need to develop new in situ technology for monitoring ocean acidification, but the potential capabilities of space-based measurements remain largely untapped. Routine measurements from space can provide quasi-synoptic, reproducible data for investigating processes on global scales; they may also be the most efficient way to monitor the ocean surface. As the carbon cycle is dominantly controlled by the balance between the biological and solubility carbon pumps, innovative methods to exploit existing satellite sea surface temperature and ocean color, and new satellite sea surface salinity measurements, are needed and will enable frequent assessment of ocean acidification parameters over large spatial scales