1,066 research outputs found

    Determination of energy-loss factors for slow electrons in hot gases Final report, 28 Apr. 1966 - 15 Aug. 1969

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    Determination of energy loss factors for slow electrons in hot gase

    A study of the surface energy balance on slopes in a tallgrass prairie

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    Four slopes (north, south, east, and west) were selected on the Konza Prairie Research Natural Area to study the effect of topography on surface energy balance and other micrometeorological variables. Energy fluxes, air temperature, and vapor pressure were measured on the sloped throughout the 1988 growing season. Net radiation was the highest on the south-facing slope and lowest on the north-facing slope, and the difference was more than 150 W/sq m (20 to 30 percent) at solar noon. For daily averages, the difference was 25 W/sq m (15 percent) early in the season and increased to 60 W/sq m (30 to 50 percent) in September. The east-facing and west-facing slopes had the same daily average net radiation, but the time of day when maximum net radiation occurred was one hour earlier for the east-facing slope and one hour later for the west-facing slope relative to solar noon. Soil heat fluxes were similar for all the slopes. The absolute values of sensible heat flux (h) was consistently lower on the north-facing slope compared with other slopes. Typical difference in the values of H between the north-facing and the south-facing slopes was 15 to 30 W/sq m. The south-facing slope had the greatest day to day fluctuation in latent heat flux as a result of interaction of net radiation, soil moisture, and green leaf area. The north-facing slope had higher air temperatures during the day and higher vapor pressures both during the day and at night when the wind was from the south

    Financial Liberalisation and Political Variables: a response to Abiad and Mody

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    We challenge recent findings by Abiad and Mody (2005) which suggest that financial liberalization has little to do with political variables. This analysis is at odds with some of the established literature, and only with difficulty comes to terms with the considerable cross-national variation in the pace, phasing, and extent of financial reforms over time. Using Abiad and Mody’s own index of financial liberalization, but slightly unbundling and refining their measures of ‘ideological affinity’ and ‘regime type’, we examine what Abiad and Mody call the ‘triggers’ of liberalisation and the dynamics of the subsequent ‘cumulative transformation’. We demonstrate the role of political variables in relation to initial liberalisation episodes, and as variables affecting the cumulative dynamics and sustainability of ongoing financial reform processes, including those which affect the acceptability and costs of liberalization. These factors include (i) shifts to – as opposed to levels in – Left government; (ii) the incidence of Left governments combined with low levels of democracy; (iii) international voter support for free markets; (iv) the extent of social safety nets; (v) the presence of multilateral and bilateral aid programs. Our empirical investigation confirms these factors as statistically significant determinants of financial liberalization, and reveal what Abiad and Mody identify as ‘learning’ to be a highly political process.

    Leadership and Teamwork in Trauma and Resuscitation.

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    Leadership skills are described by the American College of Surgeons' Advanced Trauma Life Support (ATLS) course as necessary to provide care for patients during resuscitations. However, leadership is a complex concept, and the tools used to assess the quality of leadership are poorly described, inadequately validated, and infrequently used. Despite its importance, dedicated leadership education is rarely part of physician training programs. The goals of this investigation were the following: 1. Describe how leadership and leadership style affect patient care; 2. Describe how effective leadership is measured; and 3. Describe how to train future physician leaders. We searched the PubMed database using the keywords "leadership" and then either "trauma" or "resuscitation" as title search terms, and an expert in emergency medicine and trauma then identified prospective observational and randomized controlled studies measuring leadership and teamwork quality. Study results were categorized as follows: 1) how leadership affects patient care; 2) which tools are available to measure leadership; and 3) methods to train physicians to become better leaders. We included 16 relevant studies in this review. Overall, these studies showed that strong leadership improves processes of care in trauma resuscitation including speed and completion of the primary and secondary surveys. The optimal style and structure of leadership are influenced by patient characteristics and team composition. Directive leadership is most effective when Injury Severity Score (ISS) is high or teams are inexperienced, while empowering leadership is most effective when ISS is low or teams more experienced. Many scales were employed to measure leadership. The Leader Behavior Description Questionnaire (LBDQ) was the only scale used in more than one study. Seven studies described methods for training leaders. Leadership training programs included didactic teaching followed by simulations. Although programs differed in length, intensity, and training level of participants, all programs demonstrated improved team performance. Despite the relative paucity of literature on leadership in resuscitations, this review found leadership improves processes of care in trauma and can be enhanced through dedicated training. Future research is needed to validate leadership assessment scales, develop optimal training mechanisms, and demonstrate leadership's effect on patient-level outcome

    A brief look at the history of the Deaconess Hospital, Edinburgh, 1894–1990

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    The Deaconess Hospital, Edinburgh, opened in 1894 and was the first establishment of its kind in the UK, maintained and wholly funded as it was by the Reformed Church. Through its 96-year lifetime it changed and evolved to time and circumstance. It was a school: for the training of nurses and deaconesses who took their practical skills all over the world. It was a sanctum: for the sick-poor before the NHS. It was a subsidiary: for the bigger hospitals of Edinburgh after amalgamation into the NHS. It was a specialised centre: as the Urology Department in Edinburgh and the Scottish Lithotripter centre. And now it is currently student accommodation. There is no single source to account for its history. Through the use of original material made available by the Lothian Health Services Archives – including Church of Scotland publications, patient records, a doctor’s casebook and annual reports – we review its conception, purpose, development and running; its fate on joining the NHS, its identity in the latter years and finally its closure

    Risk factors for thromboembolic complications in isolated severe head injury.

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    PURPOSE Patients with traumatic brain injury (TBI) are at high risk for venous thromboembolism (VTE). The aim of the present study is to identify factors independently associated with VTE events. Specifically, we hypothesized that the mechanism of penetrating head trauma might be an independent factor associated with increased VTE events when compared with blunt head trauma. METHODS The ACS-TQIP database (2013-2019) was queried for all patients with isolated severe head injuries (AIS 3-5) who received VTE prophylaxis with either unfractionated heparin or low-molecular-weight heparin. Transfers, patients who died within 72 h and those with a hospital length of stay < 48 h were excluded. Multivariable analysis was used as the primary analysis to identify independent risk factors for VTE in isolated severe TBI. RESULTS A total of 75,570 patients were included in the study, 71,593 (94.7%) with blunt and 3977 (5.3%) with penetrating isolated TBI. Penetrating trauma mechanism (OR 1.49, CI 95% 1.26-1.77), increasing age (age 16-45: reference; age > 45-65: OR 1.65, CI 95% 1.48-1.85; age > 65-75: OR 1.71, CI 95% 1.45-2.02; age > 75: OR 1.73, CI 95% 1.44-2.07), male gender (OR 1.53, CI 95% 1.36-1.72), obesity (OR 1.35, CI 95% 1.22-1.51), tachycardia (OR 1.31, CI 95% 1.13-1.51), increasing head AIS (AIS 3: reference; AIS 4: OR 1.52, CI 95% 1.35-1.72; AIS 5: OR 1.76, CI 95% 1.54-2.01), associated moderate injuries (AIS = 2) of the abdomen (OR 1.31, CI 95% 1.04-1.66), spine (OR 1.35, CI 95% 1.19-1.53), upper extremity (OR 1.16, CI 95% 1.02-1.31), lower extremity (OR 1.46, CI 95% 1.26-1.68), craniectomy/craniotomy or ICP monitoring (OR 2.96, CI 95% 2.65-3.31) and pre-existing hypertension (OR 1.18, CI 95% 1.05-1.32) were identified as independent risk factors for VTE complications in isolated severe head injury. Increasing GCS (OR 0.93, CI 95% 0.92-0.94), early VTE prophylaxis (OR 0.48, CI 95% 0.39-0.60) and LMWH compared to heparin (OR 0.74, CI 95% 0.68-0.82) were identified as protective factors for VTE complications. CONCLUSION The identified factors independently associated with VTE events in isolated severe TBI need to be considered in VTE prevention measures. In penetrating TBI, an even more aggressive VTE prophylaxis management may be justified as compared to that in blunt

    Scan-Negative Cauda Equina Syndrome A Prospective Cohort Study

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    Objective: To describe clinical features relevant to diagnosis, mechanism, and etiology in patients with “scan-negative” cauda equina syndrome (CES). Methods: We carried out a prospective study of consecutive patients presenting with the clinical features of CES to a regional neurosurgery center comprising semi-structured interview and questionnaires investigating presenting symptoms, neurologic examination, psychiatric and functional disorder comorbidity, bladder/bowel/sexual function, distress, and disability. Results: A total of 198 patients presented consecutively over 28 months. A total of 47 were diagnosed with scan-positive CES (mean age 48 years, 43% female). A total of 76 mixed category patients had nerve root compression/displacement without CES compression (mean age 46 years, 71% female) and 61 patients had scan-negative CES (mean age 40 years, 77% female). An alternative neurologic cause of CES emerged in 14/198 patients during admission and 4/151 patients with mean duration 25 months follow-up. Patients with scan-negative CES had more positive clinical signs of a functional neurologic disorder (11% scan-positive CES vs 34% mixed and 68% scan-negative, p < 0.0001), were more likely to describe their current back pain as worst ever (41% vs 46% and 70%, p = 0.005), and were more likely to have symptoms of a panic attack at onset (37% vs 57% and 70%, p = 0.001). Patients with scan-positive CES were more likely to have reduced/absent bilateral ankle jerks (78% vs 30% and 12%, p < 0.0001). There was no significant difference between groups in the frequency of reduced anal tone and urinary retention. Conclusion: The first well-phenotyped, prospective study of scan-negative CES supports a model in which acute pain, medication, and mechanisms overlapping with functional neurologic disorders may be relevant

    Systematic review of the incidence and clinical risk predictors of atrial fibrillation and permanent pacemaker implantation for bradycardia in Fabry disease

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    INTRODUCTION: Fabry disease (FD) is an X-linked lysosomal storage disorder caused by enzyme deficiency, leading to glycosphingolipid accumulation. Cardiac accumulation triggers local tissue injury, electrical instability and arrhythmia. Bradyarrhythmia and atrial fibrillation (AF) incidence are reported in up to 16% and 13%, respectively. OBJECTIVE: We conducted a systematic review evaluating AF burden and bradycardia requiring permanent pacemaker (PPM) implantation and report any predictive risk factors identified. METHODS: We conducted a literature search on studies in adults with FD published from inception to July 2019. Study outcomes included AF or bradycardia requiring therapy. Databases included Embase, Medline, PubMed, Web of Science, CINAHL and Cochrane. The Risk of Bias Agreement tool for Non-Randomised Studies (RoBANS) was utilised to assess bias across key areas. RESULTS: 11 studies were included, eight providing data on AF incidence or PPM implantation. Weighted estimate of event rates for AF were 12.2% and 10% for PPM. Age was associated with AF (OR 1.05–1.20 per 1-year increase in age) and a risk factor for PPM implantation (composite OR 1.03). Left ventricular hypertrophy (LVH) was associated with AF and PPM implantation. CONCLUSION: Evidence supporting AF and bradycardia requiring pacemaker implantation is limited to single-centre studies. Incidence is variable and choice of diagnostic modality plays a role in detection rate. Predictors for AF (age, LVH and atrial dilatation) and PPM (age, LVH and PR/QRS interval) were identified but strength of association was low. Incidence of AF and PPM implantation in FD are variably reported with arrhythmia burden likely much higher than previously thought

    Improved outcomes for hepatic trauma in England and Wales over a decade of trauma and hepatobiliary surgery centralisation

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    Background: Over the last decade trauma services have undergone a reconfiguration in England and Wales. The objective is to describe the epidemiology, management and outcomes for liver trauma over this period and examine factors predicting survival. Methods: Patients sustaining hepatic trauma were identified using the Trauma Audit and Research Network database. Demographics, management and outcomes were assessed between January 2005 and December 2014 and analysed over five, 2-year study periods. Independent predictor variables for the outcome of liver trauma were analysed using multiple logistic regression. Results: 4368 Patients sustained hepatic trauma (with known outcome) between January 2005 and December 2014. Median age was 34 years (interquartile range 23–49). 81% were due to blunt and 19% to penetrating trauma. Road traffic collisions were the main mechanism of injury (58.2%). 241 patients (5.5%) underwent liver-specific surgery. The overall 30-day mortality rate was 16.4%. Improvements were seen in early consultant input, frequency and timing of computed tomography (CT) scanning, use of tranexamic acid and 30-day mortality over the five time periods. Being treated in a unit with an on-site HPB service increased the odds of survival (odds ratio 3.5, 95% confidence intervals 2.7–4.5). Conclusions: Our study has shown that being treated in a unit with an on-site HPB service increased the odds of survival. Further evaluation of the benefits of trauma and HPB surgery centralisation is warranted

    FDCCS16 molecular simulation of the thermophysical properties and phase behaviour of impure CO2 relevant to CCS

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    Impurities from the CCS chain can greatly influence the physical properties of CO2. This has important design, safety and cost implications for the compression, transport and storage of CO2. There is an urgent need to understand and predict the properties of impure CO2 to assist with CCS implementation. However, CCS presents demanding modelling requirements. A suitable model must both accurately and robustly predict CO2 phase behaviour over a wide range of temperature and pressure, and maintain that predictive power for CO2 mixtures with numerous, mutually interacting chemical species. A promising technique to address this task is molecular simulation. It offers a molecular approach, with foundations in firmly established physical principles, along with the potential to predict the wide range of physical properties required for CCS. The quality of predictions from molecular simulation depends on accurate force-fields to de- scribe the interactions between CO2 and other molecules. Unfortunately, there is currently no universally applicable method to obtain force-fields suitable for molecular simulation. In this paper we present two methods of obtaining force-fields: the first being semi-empirical and the second using ab-initio quantum-chemical calculations. In the first approach we optimise the impurity force-field against measurements of the phase and pressure-volume behaviour of CO2 binary mixtures with N2, O2, Ar and H2. A gradient-free optimiser allows us to use the simulation itself as the underlying model. This leads to accurate and robust predictions under conditions relevant to CCS. In the second approach we use quantum-chemical calculations to produce ab-initio evaluations of the interactions between CO2 and relevant impurities, taking N2 as an exemplar. We use a modest number of these calculations to train a machine-learning algorithm, known as a Gaussian process, to describe these data. The resulting model is then able to accurately predict a much broader set of ab-initio force-field calculations at comparatively low numerical cost. Although our method is not yet ready to be implemented in a molecular simulation, we outline the necessary steps here. Such simulations have the potential to deliver first-principles simulation of the thermodynamic properties of impure CO2, without fitting to experimental data
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