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Internal solitary waves in the coastal ocean propagate in a complex environment, with variations in the background currents and stratification and with topography along both the bottom (e.g. sills) and sides (e.g. headlands). We present direct numerical simulations of internal solitary wave propagation past an isolated sidewall constriction on laboratory scales. We find that the wave-induced currents generate separation regions which develop into vortices above and below the wave-deformed pycnocline. These vortices yield horizontal tracer exchange between the near-wall region and channel interior and vertical transport sufficient to lift pycnocline fluid near to the surface. Quantitatively, the height of the vertical transport was found to be proportional to the square of the vertical vorticity. Increases in the wave amplitude and the aspect ratio of the constriction (height to width) led to stronger vortices, greater lateral and vertical transport and enhanced density overturning. We compare and contrast these findings with the literature on isolated bottom topography, focusing on the inherently three-dimensional nature (vorticity aligned perpendicular to isopycnals) of the instability in the sidewall case as opposed to typical instabilities caused by internal solitary waves.
Debate about the nature of climate and the magnitude of ecological change across Australia during the last glacial maximum (LGM; 26.5–19 ka) persists despite considerable research into the late Pleistocene. This is partly due to a lack of detailed paleoenvironmental records and reliable chronological frameworks. Geochemical and geochronological analyses of a 60 ka sedimentary record from Brown Lake, subtropical Queensland, are presented and considered in the context of climate-controlled environmental change. Optically stimulated luminescence dating of dune crests adjacent to prominent wetlands across North Stradbroke Island (Minjerribah) returned a mean age of 119.9 ± 10.6 ka; indicating relative dune stability soon after formation in Marine Isotope Stage 5. Synthesis of wetland sediment geochemistry across the island was used to identify dust accumulation and applied as an aridification proxy over the last glacial-interglacial cycle. A positive trend of dust deposition from ca. 50 ka was found with highest influx occurring leading into the LGM. Complexities of comparing sedimentary records and the need for robust age models are highlighted with local variation influencing the accumulation of exogenic material. An inter-site comparison suggests enhanced moisture stress regionally during the last glaciation and throughout the LGM, returning to a more positive moisture balance ca. 8 ka.
An early economic evaluation to inform the translation into clinical practice of a spectroscopic liquid biopsy for the detection of brain cancer. Two specific aims are (1) to update an existing economic model with results from a prospective study of diagnostic accuracy and (2) to explore the potential of brain tumor-type predictions to affect patient outcomes and healthcare costs.
A cost-effectiveness analysis from a UK NHS perspective of the use of spectroscopic liquid biopsy in primary and secondary care settings, as well as a cost–consequence analysis of the addition of tumor-type predictions was conducted. Decision tree models were constructed to represent simplified diagnostic pathways. Test diagnostic accuracy parameters were based on a prospective validation study. Four price points (GBP 50-200, EUR 57-228) for the test were considered.
In both settings, the use of liquid biopsy produced QALY gains. In primary care, at test costs below GBP 100 (EUR 114), testing was cost saving. At GBP 100 (EUR 114) per test, the ICER was GBP 13,279 (EUR 15,145), whereas at GBP 200 (EUR 228), the ICER was GBP 78,300 (EUR 89,301). In secondary care, the ICER ranged from GBP 11,360 (EUR 12,956) to GBP 43,870 (EUR 50,034) across the range of test costs.
The results demonstrate the potential for the technology to be cost-effective in both primary and secondary care settings. Additional studies of test use in routine primary care practice are needed to resolve the remaining issues of uncertainty—prevalence in this patient population and referral behavior.
Infants with single ventricle congenital heart disease demonstrate increasing head growth after bidirectional Glenn; however, the expected growth trajectory has not been well described.
1) We will describe the pattern of head circumference growth in the first year after bidirectional Glenn. 2) We will determine if head growth correlates with motor developmental outcomes approximately 12 months after bidirectional Glenn.
Sixty-nine single ventricle patients underwent bidirectional Glenn between 2010 and 2016. Patients with structural brain abnormalities, grade III–IV intra-ventricular haemorrhage, significant stroke, or obstructive hydrocephalus were excluded. Head circumference and body weight measurements from clinical encounters were evaluated. Motor development was measured with Psychomotor Developmental Index of the Bayley Scales of Infant Development, Third Edition. Generalised estimating equations assessed change in head circumference z-scores from baseline (time of bidirectional Glenn) to 12 months post-surgery.
Mean age at bidirectional Glenn was 4.7 (2.3) months and mean head circumference z-score based on population-normed data was −1.13 (95% CI −1.63, −0.63). Head circumference z-score increased to 0.35 (95% CI −0.20, 0.90) (p < 0.0001) 12 months post-surgery. Accelerated head growth, defined as an increase in z-score of >1 from baseline to 12 months post-surgery, was present in 46/69 (66.7%) patients. There was no difference in motor Psychomotor Developmental Index scores between patients with and without accelerated head growth.
Single ventricle patients demonstrated a significant increase in head circumference after bidirectional Glenn until 10–12 months post-surgery, at which time growth stabilised. Accelerated head growth did not predict sub-sequent motor developmental outcomes.
Infectious mononucleosis is typically a self-limited viral infection of adolescence and early adulthood that resolves in a period of weeks, causing no major sequelae. We describe a case of a healthy 18-year-old female diagnosed with infectious mononucleosis who also presented with right upper quadrant abdominal pain, moderate transaminitis, and cholestatic biochemistry. An ultrasound revealed acute acalculous cholecystitis, generally a condition seen in the context of critical illness. Further investigating emergency department patients with infectious mononucleosis is often not indicated, but may be important for those who present atypically.
We argue that democratic institutions influence property rights in attracting foreign direct investment (FDI) by providing: (1) a coherent logic to the property rights regime that is created in a state and (2) a legitimate way to manage conflicts that arise in dynamic economies. We expect that the marginal effect of property rights in attracting FDI has increased over time with the rate of technological dynamism. We test this using a non-nested multilevel modeling strategy with random coefficients on data from 1970 to 2009. Our results demonstrate that the effect of property rights on attracting FDI is contingent on democratic institutions and that this effect becomes more pronounced over time. This effect holds for both developing and developed countries across all regions.
Our research group recently evaluated a minimally invasive surgical procedure in order to inform a reimbursement decision. The application for funding was designed around the study selection criteria from a single pivotal randomized controlled trial (RCT). The aim of this study review was to evaluate the safety and effectiveness of this minimally invasive surgical procedure, and document challenges faced in evaluating a technology based on a highly targeted population.
A systematic literature search of four biomedical databases was conducted (PubMed, Embase, Cochrane library, York CRD) up to 8 August 2017. Specific elements related to the population were patient age, together with level and duration of pain. Primary effectiveness outcomes included pain, patient reported quality of life, mortality and adverse events. The included RCTs were critically appraised against the Cochrane risk of bias tool. Meta-analysis was not possible due to the limited availability of evidence with consistent outcomes.
From 4,718 search results, only one pivotal RCT specifically met the inclusion criteria, which demonstrated favorable safety and effectiveness of the procedure; however, the sample population in the trial had limited external validity to the proposed reimbursement population and follow-up was limited to six months. As a result, the selection criteria were broadened to better reflect the manner in which the service may be provided in clinical practice, and capture longer-term safety concerns. Four additional RCTs were included, which provided contradictory results.
The results of this review identified two important issues in evaluating a health technology where the assessment has been focused to the results of a single trial. In particular, the generalizability of a trial is defined by the demographic distribution of the sample, not the selection criteria. Designing the review selection criteria around the selection criteria for a single trial can have consequences for a funding decision.
Background: Neurosurgical residents face a unique combination of challenges, including long duty hours, technically challenging cases, and uncertain employment prospects. We sought to assess the demographics, interests, career goals, self-rated happiness, and overall well-being of Canadian neurosurgery residents. Methods: A cross-sectional survey was developed and sent through the Canadian Neurosurgery Research Collaborative to every resident enrolled in a Canadian neurosurgery program as of April 1, 2016. Results: We analyzed 76 completed surveys of 146 eligible residents (52% response rate). The median age was 29 years, with 76% of respondents being males. The most popular subspecialties of interest for fellowship were spine, oncology, and open vascular neurosurgery. The most frequent self-reported number of worked hours per week was the 80- to 89-hour range. The majority of respondents reported a high level of happiness as well as stress. Sense of accomplishment and fatigue were reported as average to high and overall quality of life was low for 19%, average for 49%, and high for 32%. Satisfaction with work-life balance was average for 44% of respondents and was the only tested domain in which significant dissatisfaction was identified (18%). Overall, respondents were highly satisfied with their choice of specialty, choice of program, surgical exposure, and work environment; however, intimidation was reported in 36% of respondents and depression by 17%. Conclusions: Despite a challenging residency and high workload, the majority of Canadian neurosurgery residents are happy and satisfied with their choice of specialty and program. However, work-life balance, employability, resident intimidation, and depression were identified as areas of active concern.