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When open-cut mines are eventually abandoned, they leave a large hole with sloping sides. The hole fills with rain water, and there is also contaminated run-off from surrounding land, that moves through the rock and eventually through the sloping sides of the abandoned mine. This paper considers a two-dimensional unsteady model motivated by this leaching flow through the rock and into the rain-water reservoir. The stability of the interface between the two fluids is analysed in the inviscid limit. A viscous Boussinesq model is also presented, and a closed-form solution is presented to this problem, after it has been linearized in a manner consistent with Boussinesq theory. That solution suggests that the interfacial zone is effectively neutrally stable as it evolves in time. However, an asymptotic theory in the interfacial region shows the interface to be unstable. In addition, the nonlinear Boussinesq model is solved using a spectral method. Interfacial travelling waves and roll-up are observed and discussed, and compared against the predictions of asymptotic Boussinesq theory.
Rayleigh–Taylor instability occurs when a heavier fluid overlies a lighter fluid, and the two seek to exchange positions under the effect of gravity. We present a linearized theory for arbitrary three-dimensional (3D) initial disturbances that grow in time, and calculate the evolution of the interface for early times. A new spectral method is introduced for the fully 3D nonlinear problem in a Boussinesq fluid, where the interface between the light and heavy fluids is approximated with a smooth but rapid density change in the fluid. The results of large-scale numerical calculation are presented in fully 3D geometry, and compared and contrasted with the early-time linearized theory.
We consider fluid in a channel of finite height. There is a circular hole in the channel bottom, through which fluid of a lower density is injected and rises to form a plume. Viscous boundary layers close to the top and bottom of the channel are assumed to be so thin that the viscous fluid effectively slips along each of these boundaries. The problem is solved using a novel spectral method, in which Hankel transforms are first used to create a steady-state axisymmetric (inviscid) background flow that exactly satisfies the boundary conditions. A viscous correction is then added, so as to satisfy the time-dependent Boussinesq Navier–Stokes equations within the fluid, leaving the boundary conditions intact. Results are presented for the “lazy” plume, in which the fluid rises due only to its own buoyancy, and we study in detail its evolution with time to form an overturning structure. Some results for momentum-driven plumes are also presented, and the effect of the upper wall of the channel on the evolution of the axisymmetric plume is discussed.
Acute pulmonary embolism is a life-threatening condition and rarely occurs in children. In adults, catheter-directed therapy emerges as a potentially safer and effective therapeutic option. However, there is a paucity of data on the safety and efficacy of catheter-directed therapy for pulmonary embolism in children. We report a single-centred experience of catheter-directed therapy for acute pulmonary embolism in children.
This is a retrospective study of children who had no CHD and underwent catheter-directed therapy at Detroit Medical Center during a 12-year period from 2005 to 2017. Demographic and clinical data associated with pulmonary embolism were collected along with the outcome.
A total of nine patients of median age 16 years with the range from 12 to 20 received catheter-directed therapy for sub-massive (n = 6) and massive pulmonary embolism (n = 3). Among nine patients, one patient received Angiojet thrombectomy and balloon angioplasty, whereas eight patients received catheter-directed thrombolysis using tissue plasminogen activator through infusion catheters (n = 3) or EkoSonic ultrasound-accelerated thrombolysis system (n = 5). In four out of five patients treated with EkoSonic, significant clinical improvement was noticed within 24 hours. Among seven patients who survived, two patients had minor gastrointestinal bleeding with median hospital stay of 8 days with the range from 5 to 24 days, and two patients with massive pulmonary embolism died possibly due to delayed institution of catheter-directed therapy.
Catheter-directed therapy with/without EkoSonic is an emerging alternative therapy for sub-massive and massive pulmonary embolism in children. A timely institution of catheter-directed therapy appeared important to improve the outcome.
Detailed representation of ingesta inflow to and digesta outflow from the rumen is critical for improving the modelling of rumen function and herbage intake of grazing ruminants. The objective of the current work was to extend a mechanistic model of a grazing ruminant, MINDY, to simulate the dynamic links between ingestive and digestive processes as affected by forage and sward features (e.g. sward structure, herbage chemical composition) as well as the internal state of the animal. The work integrates existing aspects of forage ingestion, oral physiology and rumen digestion that influence ingesta characteristics and digesta outflows from the rumen, respectively. The paper describes the structure and function of the new development, assessing the new model in terms of dynamic changes of oral processing of ingesta and rumen dilution rate under different grazing contexts. MINDY reproduces characteristics of ingesta inflow to and digesta outflow from the rumen of grazing ruminants, achieving temporal patterns of occurrence within and between meals, similar to those for grazing animals reported in the literature. The model realistically simulates changes in particle size distribution of the ingestive bolus, bolus weight and rumen dilution rate in response to contrasting grazing management regimes. The new concepts encoded in MINDY capture the underlying biological mechanisms that drive the dynamic link between ingestion and digestion patterns. This development advances in the understanding and modelling of grazing and digestive behaviour patterns of free-ranging ruminants.
The mental health and social functioning of millions of forcibly displaced individuals worldwide represents a key public health priority for host governments. This is the first longitudinal study with a representative sample to examine the impact of interpersonal trust and psychological symptoms on community engagement in refugees.
Participants were 1894 resettled refugees, assessed within 6 months of receiving a permanent visa in Australia, and again 2–3 years later. Variables measured included post-traumatic stress disorder symptoms, depression/anxiety symptoms, interpersonal trust and engagement with refugees’ own and other communities.
A multilevel path analysis was conducted, with the final model evidencing good fit (Comparative Fit Index = 0.97, Tucker–Lewis Index = 0.89, Root Mean Square Error of Approximation = 0.05, Standardized Root-Mean-Square-Residual = 0.05). Findings revealed that high levels of depression symptoms were associated with lower subsequent engagement with refugees’ own communities. In contrast, low levels of interpersonal trust were associated with lower engagement with the host community over the same timeframe.
Findings point to differential pathways to social engagement in the medium-term post-resettlement. Results indicate that depression symptoms are linked to reduced engagement with one's own community, while interpersonal trust is implicated in engagement with the broader community in the host country. These findings have potentially important implications for policy and clinical practice, suggesting that clinical and support services should target psychological symptoms and interpersonal processes when fostering positive adaptation in resettled refugees.
The use of roman numerals for stellar populations represents a classification approach to galaxy formation which is now well behind us. Nevertheless, the concept of a pristine generation of stars, followed by a protogalactic era, and finally the mainstream stellar population is a plausible starting point for testing our physical understanding of early star formation. This will be observationally driven as never before in the coming decade. In this paper, we search out observational tests of an idealised coeval and homogeneous distribution of population II stars. We examine the spatial distribution of quasars, globular clusters, and the integrated free electron density of the intergalactic medium, in order to test the assumption of homogeneity. Any real inhomogeneity implies a population II that is not coeval.
Measurement of water consumption and urinary nitrogen (UN) excretion of individual grazing ruminants is difficult, time-consuming and expensive. Therefore, prediction and modelling are critical for research to improve N and water use efficiency. The objective of the current work was to use a mechanistic model of a grazing ruminant, MINDY, to represent drinking and urination diurnal patterns, and the resulting pattern of UN excretion. This work is primarily an integration of existing knowledge of basic urination physiology and water dynamics in ruminants. MINDY reproduces observed patterns of urination achieving the correct temporal occurrence, relative volumes and nitrogen (N) concentration of individual urination events for a grazing dairy cow, comparable with those reported in the literature. The model simulates daily water imbibed and UN realistically, as well as ingestion rates for herbages with different protein content and contrasting grazing managements. Results of a cross-validation indicate that the root mean square prediction error and mean absolute error as % of the observed mean, respectively, were 26 and 23% for daily water imbibed, 26 and 27% for urination volume, and 25 and 19% for the frequency of urination. Although further parameterization and validation are needed, for a new development in an exploratory model like MINDY, these numbers are encouraging and reflect that the concepts encoded capture many of the underlying biological mechanisms that drive the diurnal pattern and daily UN excretion, as well as thirst, acceptable.
Anomalous drainage of the right superior caval vein into the left atrium is a rare congenital anomaly that causes cyanosis and occult infection owing to right-to-left shunting. Transcatheter management of this anomaly is unique and rarely reported. We report a 32-year-old man with a history of brain abscess, who was diagnosed with an anomalous right superior caval vein draining to the left atrium; right upper pulmonary vein and right middle pulmonary vein draining into the inferior portion of the right superior caval vein; and a left superior caval vein draining into the right atrium through the coronary sinus without a bridging vein. Pre-procedural planning was guided by three-dimensional printed model. The right superior caval vein was occluded with a 16-mm Amplatzer muscular Ventricular Septal Defect occluder inferior to the azygous vein, but superior to the entries of right upper and middle pulmonary veins. This diverted the right superior caval vein flow to the inferior caval vein system through the azygos vein in a retrograde manner and allowed the right upper pulmonary vein and right middle pulmonary vein flow to drain into the left atrium normally, achieving exclusion of right-to-left shunting and allowing normal drainage of pulmonary veins into the left atrium. At the 6-month follow-up, his saturation improved from 93 to 97% with no symptoms of superior caval vein syndrome.
To determine the patterns and predictors of treatment response trajectories for veterans with post-traumatic stress disorder (PTSD).
Conditional latent growth mixture modelling was used to identify classes and predictors of class membership. In total, 2686 veterans treated for PTSD between 2002 and 2015 across 14 hospitals in Australia completed the PTSD Checklist at intake, discharge, and 3 and 9 months follow-up. Predictor variables included co-morbid mental health problems, relationship functioning, employment and compensation status.
Five distinct classes were found: those with the most severe PTSD at intake separated into a relatively large class (32.5%) with small change, and a small class (3%) with a large change. Those with slightly less severe PTSD separated into one class comprising 49.9% of the total sample with large change effects, and a second class comprising 7.9% with extremely large treatment effects. The final class (6.7%) with least severe PTSD at intake also showed a large treatment effect. Of the multiple predictor variables, depression and guilt were the only two found to predict differences in response trajectories.
These findings highlight the importance of assessing guilt and depression prior to treatment for PTSD, and for severe cases with co-morbid guilt and depression, considering an approach to trauma-focused therapy that specifically targets guilt and depression-related cognitions.
Parents may experience anxiety and stress when their children undergo cardiac catheterisation. The goal of this study was to assess the level of anxiety in parents of children undergoing cardiac catheterisation and to identify factors that were associated with level of anxiety.
This was a cross-sectional survey of parents of children who underwent cardiac catheterisation. Anxiety levels were measured using a validated self-report questionnaire – State-Trait Anxiety Inventory, which generates state anxiety scores on the current state of anxiety and trait anxiety scores on the stable aspects of anxiety proneness. One sample t-test was used to compare the data with normative data. Multiple linear regression was used to assess the factors associated with the state score.
A total of 113 parents completed the survey. The mean age of parents was 34.0±7.7 years and the mean age of children undergoing catheterisation was 6.7±5.7 years. Compared with normative data, mean state score was significantly higher in our cohort (p<0.05) despite no difference in the trait score. Final multivariate model showed that the state score was significantly associated with child age group (<1 year [coefficient β 7.2] and 10–18 years [6.3], compared to 1 to <10 years of age [reference]) and history of previous catheterisation (−5.2) (p<0.05).
Concurrent state anxiety level was high among parents of children undergoing cardiac catheterisation, whereas trait anxiety level was not. Higher anxiety was experienced by parents of infants and adolescents without a history of previous catheterisation.
In this brief communication, a new method is outlined for modelling magnification patterns on an observer’s plane using a first-order approximation to the null geodesic path equations for a point mass lens. For each ray emitted from a source, an explicit calculation is made for the change in position on the observer’s plane due to each lens mass. By counting the number of points in each small area of the observer’s plane, the magnification at that point can be determined. This allows for a very simple and transparent algorithm. A short Matlab code sample for creating simple magnification maps due to multiple point lenses is included in an appendix.
Identifying youth who may engage in future substance use could facilitate early identification of substance use disorder vulnerability. We aimed to identify biomarkers that predicted future substance use in psychiatrically un-well youth.
LASSO regression for variable selection was used to predict substance use 24.3 months after neuroimaging assessment in 73 behaviorally and emotionally dysregulated youth aged 13.9 (s.d. = 2.0) years, 30 female, from three clinical sites in the Longitudinal Assessment of Manic Symptoms (LAMS) study. Predictor variables included neural activity during a reward task, cortical thickness, and clinical and demographic variables.
Future substance use was associated with higher left middle prefrontal cortex activity, lower left ventral anterior insula activity, thicker caudal anterior cingulate cortex, higher depression and lower mania scores, not using antipsychotic medication, more parental stress, older age. This combination of variables explained 60.4% of the variance in future substance use, and accurately classified 83.6%.
These variables explained a large proportion of the variance, were useful classifiers of future substance use, and showed the value of combining multiple domains to provide a comprehensive understanding of substance use development. This may be a step toward identifying neural measures that can identify future substance use disorder risk, and act as targets for therapeutic interventions.
Integral field unit spectrographs allow the 2D exploration of the kinematics and stellar populations of galaxies, although they are generally restricted to small fields-of-view. Using the large field-of-view of the DEIMOS multislit spectrograph on Keck and our Stellar Kinematics using Multiple Slits technique, we are able to extract sky-subtracted stellar light spectra to large galactocentric radii. Here, we present a new DEIMOS mask design named SuperSKiMS that explores large spatial scales without sacrificing high spatial sampling. We simulate a set of observations with such a mask design on the nearby galaxy NGC 1023, measuring stellar kinematics and metallicities out to where the galaxy surface brightness is orders of magnitude fainter than the sky. With this technique we also reproduce the results from literature integral field spectroscopy in the innermost galaxy regions. In particular, we use the simulated NGC 1023 kinematics to model its total mass distribution to large radii, obtaining comparable results with those from published integral field unit observation. Finally, from new spectra of NGC 1023, we obtain stellar 2D kinematics and metallicity distributions that show good agreement with integral field spectroscopy results in the overlapping regions. In particular, we do not find a significant offset between our Stellar Kinematics using Multiple Slits and the ATLAS3D stellar velocity dispersion at the same spatial locations.
Original studies published over the last decade regarding time trends in dementia report mixed results. The aims of the present study were to use linked administrative health data for the province of Saskatchewan for the period 2005/2006 to 2012/2013 to: (1) examine simultaneous temporal trends in annual age- and sex-specific dementia incidence and prevalence among individuals aged 45 and older, and (2) stratify the changes in incidence over time by database of identification.
Using a population-based retrospective cohort study design, data were extracted from seven provincial administrative health databases linked by a unique anonymized identification number. Individuals 45 years and older at first identification of dementia between April 1, 2005 and March 31, 2013 were included, based on case definition criteria met within any one of four administrative health databases (hospital, physician, prescription drug, and long-term care).
Between 2005/2006 and 2012/2013, the 12-month age-standardized incidence rate of dementia declined significantly by 11.07% and the 12-month age-standardized prevalence increased significantly by 30.54%. The number of incident cases decreased from 3,389 to 3,270 and the number of prevalent cases increased from 8,795 to 13,012. Incidence rate reductions were observed in every database of identification.
We observed a simultaneous trend of decreasing incidence and increasing prevalence of dementia over a relatively short 8-year time period from 2005/2006 to 2012/2013. These trends indicate that the average survival time of dementia is lengthening. Continued observation of these time trends is warranted given the short study period.
The total magnification due to a point lens has been of particular interest as the theorem that gravitational lensing results in light amplification for all observers appears to contradict the conservation of photon number. This has been discussed several times, and various resolutions have been offered. In this note, we use a kinematic approach to provide a formula for the magnification factor for the primary image accurate to first order and valid for rays leaving the source at any trajectory. We thus determine the magnification over a sphere surrounding the system. A new result found is that while the magnification dips below unity far from the optical axis as noted by others, it returns to unity directly behind the source.
The effect of Hybrid stage 1 palliation for hypoplastic left heart syndrome on right ventricular function is unknown. We sought to compare right ventricular function in normal neonates and those with hypoplastic left heart syndrome before Hybrid palliation and to assess the effect of Hybrid palliation on right ventricular function, using the right ventricular myocardial performance index and the ratio of systolic and diastolic durations.
We carried out a retrospective review of echocardiographic data on 23 infants with hypoplastic left heart syndrome who underwent Hybrid palliation and 35 normal controls. Data were acquired before Hybrid and after Hybrid palliation – post 1, 0–4 days; post 2, 1 week; post 3, 2–3 weeks; post 4, 1–1.5 months following Hybrid palliation.
Myocardial performance index and ratio of systolic and diastolic durations were higher in the pre-Hybrid hypoplastic left heart syndrome group (n=23) – 0.47±0.16 versus 0.25±0.07, p<0.001; 1.59±0.44 versus 1.09±0.14, p<0.0001 – compared with controls (n=35). There was no significant change in the myocardial performance index at any of the post-Hybrid time points. Ratio of systolic and diastolic durations increased significantly 2 weeks after Hybrid – post 3: 2.08±0.62 and post 4: 2.21±0.45 versus pre: 1.59±0.44, p=0.043 and 0.003. There were no significant differences in parameters between sub-groups of infants who died (n=10) and survivors (n=13).
Right ventricular myocardial performance index and ratio of systolic and diastolic durations were significantly higher in infants with hypoplastic left heart syndrome before intervention compared with controls. The ratio of systolic and diastolic durations increased significantly 2 weeks after Hybrid palliation. Our data suggest that infants with hypoplastic left heart syndrome have right ventricular dysfunction before intervention, which worsens over 2 weeks after Hybrid palliation.
Both maternal obesity and disordered mood have adverse effects on pregnancy outcome. We hypothesized that maternal very severe obesity (SO) is associated with increased anxiety and depression (A&D) symptoms during pregnancy, with adverse effects on gestational weight gain (GWG), postpartum mood and postpartum weight retention (PPWR) and explored any mediation by circulating glucocorticoids.
We measured A&D symptoms with validated questionnaires at weeks 17 and 28 of pregnancy and 3 months postpartum in 135 lean [body mass index (BMI) ⩽25 kg/m2] and 222 SO (BMI ⩾40 kg/m2) pregnant women. Fasting serum cortisol was measured by radioimmunoassay; GWG and PPWR were recorded.
A&D symptoms were higher in the SO group during pregnancy and postpartum despite adjusting for multiple confounders including previous mental health diagnosis (p < 0.05), and were non-linearly correlated with total GWG (anxiety R2 = 0.06, p = 0.037; depression R2 = 0.09, p = 0.001). In the SO group only, increased maternal anxiety (β = 0.33, p = 0.03) and depression (β = 0.19, p = 0.04) symptoms at week 17 of pregnancy were associated with increased PPWR, independent of total GWG and breastfeeding. Anxiety symptoms at week 28 of pregnancy, but not depression, were non-linearly correlated with serum cortisol level at week 36 of pregnancy (R2 = 0.06, p = 0.02). Cortisol did not mediate the link between A&D symptoms and GWG.
Maternal SO was associated with increased A&D symptoms, and with adverse effects on GWG and PPWR independent of circulating glucocorticoids. Strategies to optimize GWG and postpartum weight management in SO women should include assessment and management of maternal mood in early pregnancy.
The Kelvin–Helmholtz flow is a shearing instability that occurs at the interface between two fluids moving with different speeds. Here, the two fluids are each of finite depth, but are highly viscous. Consequently, their motion is caused by the horizontal speeds of the two walls above and below each fluid layer. The motion of the fluids is assumed to be governed by the Stokes approximation for slow viscous flow, and the fluid motion is thus responsible for movement of the interface between them. A linearized solution is presented, from which the decay rate and the group speed of the wave system may be obtained. The nonlinear equations are solved using a novel spectral representation for the streamfunctions in each of the two fluid layers, and the exact boundary conditions are applied at the unknown interface location. Results are presented for the wave profiles, and the behaviour of the curvature of the interface is discussed. These results are compared to the Boussinesq–Stokes approximation which is also solved by a novel spectral technique, and agreement between the results supports the numerical calculations.