Prospective review of 30-day morbidity and mortality in a paediatric neurosurgical unit

Purpose: The purpose of this study is to record the 30-day and inpatient morbidity and mortality in paediatric patients in a tertiary neuroscience centre over a 2-year period. The intentions were to establish the frequency of significant adverse events, review the current published rates of morbidity in paediatric neurosurgical patients and propose three clinical indicators for future comparison. Methods: All deaths and adverse events were prospectively recorded from 1 January 2014 to 31 December 2015. Each adverse event was categorised, allocated a clinical impact severity score and linked to a neurosurgical procedure wherever possible. Where a patient suffered several adverse events in the same admission, each event was recorded separately. If a patient had been discharged home, an adverse event was recorded if it occurred within 30 days of admission. Results: Five hundred forty-nine procedures were performed in 287 patients (aged <16 years). One hundred thirty significant adverse events were identified. The following are the three clinical indicators: significant adverse event rate: 111 (20.2%) operations were linked to at least one significant adverse event; unscheduled return to theatre rate: 81 (14.8%) operations were associated with an adverse event that resulted in an unscheduled return to theatre; and surgical site infection rate: 29 (5.3%) operations were associated with an infection. Conclusion: Complications and adverse events are common in paediatric neurosurgery. Prospective, continuous surveillance will promote both quality assurance and quality improvement in the neurosurgical care delivered to patients

Short course on principles and applications of beach nourishment

Covers the engineering aspects of beach nourishment. (Document is 192 pages

The treatment of mixing in core helium burning models -- III. Suppressing core breathing pulses with a new constraint on overshoot

Theoretical predictions for the core helium burning phase of stellar evolution are highly sensitive to the uncertain treatment of mixing at convective boundaries. In the last few years, interest in constraining the uncertain structure of their deep interiors has been renewed by insights from asteroseismology. Recently, Spruit (2015) proposed a limit for the rate of growth of helium-burning convective cores based on the higher buoyancy of material ingested from outside the convective core. In this paper we test the implications of such a limit for stellar models with a range of initial mass and metallicity. We find that the constraint on mixing beyond the Schwarzschild boundary has a significant effect on the evolution late in core helium burning, when core breathing pulses occur and the ingestion rate of helium is fastest. Ordinarily, core breathing pulses prolong the core helium burning lifetime to such an extent that models are at odds with observations of globular cluster populations. Across a wide range of initial stellar masses ($0.83 \leq M/\text{M}_\odot \leq 5$), applying the Spruit constraint reduces the core helium burning lifetime because core breathing pulses are either avoided or their number and severity reduced. The constraint suggested by Spruit therefore helps to resolve significant discrepancies between observations and theoretical predictions. Specifically, we find improved agreement for $R_2$, the observed ratio of asymptotic giant branch to horizontal branch stars in globular clusters; the luminosity difference between these two groups; and in asteroseismology, the mixed-mode period spacing detected in red clump stars in the \textit{Kepler} field.Comment: Accepted for publication in MNRAS; 11 pages, 6 figure

The state of our interstates

President Obama's budget proposal emphasizes the importance of infrastructure investments for the nation's economic health, so now seems a good time to assess the condition of our country's major roads.Express highways

Criticality, factorization and long-range correlations in the anisotropic XY-model

We study the long-range quantum correlations in the anisotropic XY-model. By first examining the thermodynamic limit we show that employing the quantum discord as a figure of merit allows one to capture the main features of the model at zero temperature. Further, by considering suitably large site separations we find that these correlations obey a simple scaling behavior for finite temperatures, allowing for efficient estimation of the critical point. We also address ground-state factorization of this model by explicitly considering finite size systems, showing its relation to the energy spectrum and explaining the persistence of the phenomenon at finite temperatures. Finally, we compute the fidelity between finite and infinite systems in order to show that remarkably small system sizes can closely approximate the thermodynamic limit.Comment: 8 pages, 8 figures. Close to published versio