To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure no-reply@cambridge.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
This study presents a comprehensive analysis of the frequency response characteristics in a gas generator cycle liquid rocket engine, employing modular decomposition and linearised frequency-domain modeling to simulate dynamic behaviours under forced oscillations. The engine is dissected into key subsystems, including liquid pipelines, turbopump assembly, valves, flow regulation components, thrust chamber, gas generator and pyrotechnic starter, highlighting features such as centrifugal pump pressurisation, staged combustion and cavitation mitigation via venturis. Three oscillation scenarios are examined: supply system responses to thrust chamber pressure disturbances, combustion component responses to fluid disturbances and combustion component responses to pump speed disturbances. Simulations over 0–2000 Hz reveal acoustic-dominated traits in the thrust chamber with oxidiser pathway dominance, low-frequency emphasis in the gas generator driven by fuel disturbances, and heightened instability risks from pump pulsations. Parametric analyses demonstrate that increased pipeline lengths shift resonant frequencies downward, elevated injector pressure drops enhance stability margins by 1.6% with a 20% pressure drop increase, and chamber structural/gas parameter variations erode system stability. These insights, validated against benchmark models, inform strategies for mitigating combustion instability, optimising design parameters, and improving reliability in high-thrust propulsion applications.
We consider the problem of estimating fractional processes based on noisy high-frequency data. Generalizing the idea of pre-averaging to a fractional setting, we exhibit a sequence of consistent estimators for the unknown parameters of interest by proving a law of large numbers for associated variation functionals. In contrast to the semimartingale setting, the optimal window size for pre-averaging depends on the unknown roughness parameter of the underlying process. We evaluate the performance of our estimators in a simulation study and use them to empirically verify Kolmogorov’s $2/3$-law in turbulence data contaminated by instrument noise.
Patients with stroke or transient ischemic attack (TIA) are at high early risk of mortality and morbidity. Current risk prediction tools focus on patients after hospital discharge but not on those surviving to outpatient follow-up. We examined whether demographic and medical history data could predict 1-year stroke recurrence and mortality, among those discharged alive and event-free for 90 days after stroke and 1 day after TIA.
Methods:
Data were obtained from the Ontario Stroke Registry (13,848 stroke and 13,059 TIA patients) and linked to administrative databases. Two-thirds of each cohort were used for model derivation and one-third for validation. Multivariable regression models were used to predict stroke recurrence and all-cause mortality.
Results:
There were 238 (2.71%) recurrent strokes in the ischemic stroke and 298 (3.44%) in the TIA cohorts at one year. Increasing age and previous stroke/TIA were associated with an increased risk of recurrent stroke in both cohorts. A higher modified Rankin Scale and diabetes were associated with an increased risk of recurrent stroke in the stroke cohort and heart failure, smoking and discharge location in the TIA cohort. Time-dependent areas under the curve were modest, 0.59 (0.54–0.64) and 0.59 (0.55–0.64) for the stroke and TIA validation cohorts, respectively. C-statistics from derivation and validation cohorts for mortality ranged from 0.74–0.78.
Conclusion:
The predictive accuracy of the models was quite low after accounting for several risk factors. Additional risk factors associated with stroke recurrence for people seen in outpatient stroke clinics, and innovative approaches to individualized secondary prevention are needed.
Species of the Burkholderia (B.) cepacia complex (Bcc) have been implicated in multiple nosocomial outbreaks linked to contaminated water-based products, including liquid soaps, mouthwash, and other non-alcoholic aqueous solutions.
Objective:
We describe two substantial healthcare-associated outbreaks of Bcc (B. cepacia and B. contaminans) in the United Kingdom and Ireland associated with contaminated products. We highlight the challenges during investigation and mitigation, and provide recommendations.
Methods:
A multidisciplinary, multi-stakeholder investigation across both outbreaks was adopted, involving interviews, trawling questionnaires, and targeted product sampling.
Results:
There were 153 and 66 confirmed cases in the B. cepacia and B. contaminans outbreaks, respectively. Cases predominantly comprised hospitalized individuals, and 70% of isolates were recovered from an invasive site. The outbreak strain of B. cepacia was isolated from non-sterile ultrasound gel. An analytical study suggested the B. contaminans cluster was also linked to ultrasound gel; however, a disinfectant wipe product was subsequently identified as the source (0–3 single nucleotide polymorphism differences between case and wipe isolates).
Outbreak control measures:
The affected disinfectant wipes were withdrawn. The ultrasound gel was not recalled but health system procurement was suspended, rapid clinical guidance was produced and a National Patient Safety Alert was issued. Inter-organizational partnership was required to mitigate risks.
Conclusion:
Identifying the source of outbreaks associated with contaminated products can be challenging, requiring complex multi-stakeholder interventions. We recommend a low threshold for investigation of Bcc clusters, adopting a multidisciplinary approach to investigation and mitigation, implementing interventions focusing on practice, and prompt product removal to protect patients.
Previous results show that women who suffered from perinatal depression (PND) have a higher risk of suicidal behavior. However, clinical tools for predicting suicidal behavior among patients with PND are lacking.
Objectives
To develop a prediction model for suicidal behavior after PND using machine learning.
Methods
Leveraging nationwide Swedish register data, we included 57,848 women with PND diagnosed during 2001-2018 and identified 2,303 events of suicidal behavior up to 5 years after PND diagnosis. Based on our previous association studies, 16 predictors containing information on demographics and pregnancy characteristics were included after multiple imputation. The sample was randomly split into 80% as a training set and 20% for testing. Classification and Regression Tree (CART), Random Forest (RF), Naïve Bayes (NB) and Logistic regression (LR) were used to establish prediction models with area under the curve (AUC) assessed for prediction performance. 10-fold cross-validation was used to evaluate the algorithms on unseen data.
Results
In the prediction models, the CART yielded the best performance for suicidal behavior within 5 years after PND diagnosis (AUC 0.78, 95% CI 0.76-0.81). The population that scored highest (17%) in CART model had 84% risk of suicidal behavior. LR also had a comparable performance (AUC 0.78, 95% CI 0.76-0.81), whereas RF (AUC 0.74, 95% CI 0.72-0.76) and NB (AUC 0.70, 95% CI 0.68-0.72) had relatively poor performance. Notably, suicide history was a main contributor in all four models. Other predictors like household income, gestational age and education level were also important indicators of suicidal behavior risk.
Conclusions
The machine learning models have promising prediction performance for suicidal behavior after PND. Yet, further improvement is needed before clinical implementation.
The quality of news reports about suicide can influence suicide rates. Although many researchers have aimed to assess the general safety of news reporting in terms of adherence to responsible media guidelines, none have focused on major US cable networks, a key source of public information in North America and beyond.
Aims
To characterise and compare suicide-related reporting by major US cable television news networks across the ideological spectrum.
Method
We searched a news archive (Factiva) for suicide-related transcripts from ‘the big three’ US cable television news networks (CNN, Fox News and MSNBC) over an 11-year inclusion interval (2012–2022). We included and coded segments with a major focus on suicide (death, attempt and/or thoughts) for general content, putatively harmful and protective characteristics and overarching narratives. We used chi-square tests to compare these variables across networks.
Results
We identified 612 unique suicide-related segments (CNN, 398; Fox News, 119; MSNBC, 95). Across all networks, these segments tended to focus on suicide death (72–89%) and presented stories about specific individuals (61–87%). Multiple putatively harmful characteristics were evident in segments across networks, including mention of a suicide method (42–52%) – with hanging (15–30%) and firearm use (12–20%) the most commonly mentioned – and stigmatising language (39–43%). Only 15 segments (2%) presented a story of survival.
Conclusions
Coverage of suicide stories by major US cable news networks was often inconsistent with responsible reporting guidelines. Further engagement with networks and journalists is thus warranted.
Transcranial direct current stimulation (tDCS) is a promising treatment for major depressive disorder (MDD). This study evaluated its antidepressant and cognitive effects as a safe, effective, home-based therapy for MDD.
Methods
This double-blind, sham-controlled, randomized trial divided participants into low-intensity (1 mA, n = 47), high-intensity (2 mA, n = 49), and sham (n = 45) groups, receiving 42 daily tDCS sessions, including weekends and holidays, targeting the dorsolateral prefrontal cortex for 30 minutes. Assessments were conducted at baseline and weeks 2, 4, and 6. The primary outcome was cognitive improvement assessed by changes in total accuracy on the 2-back test from baseline to week 6. Secondary outcomes included changes in depressive symptoms (HAM-D), anxiety (HAM-A), and quality of life (QLES). Adverse events were monitored. This trial was registered with ClinicalTrials.gov (NCT04709952).
Results
In the tDCS study, of 141 participants (102 [72.3%] women; mean age 35.7 years, standard deviation 12.7), 95 completed the trial. Mean changes in the total accuracy scores from baseline to week 6 were compared across the three groups using an F-test. Linear mixed-effects models examined the interaction of group and time. Results showed no significant differences among groups in cognitive or depressive outcomes at week 6. Active groups experienced more mild adverse events compared to sham but had similar rates of severe adverse events and dropout.
Conclusions
Home-based tDCS for MDD demonstrated no evidence of effectiveness but was safe and well-tolerated. Further research is needed to address the technical limitations, evaluate broader cognitive functions, and extend durations to evaluate its therapeutic potential.
In this paper, a class of probability models for ranking data, the order-statistics models, is investigated. We extend the usual normal order-statistics model into one where the underlying random variables follow a multivariate normal distribution. Bayesian approach and the Gibbs sampling technique are used for parameter estimation. In addition, methods to assess the adequacy of model fit are introduced. Robustness of the model is studied by considering a multivariate-t distribution. The proposed method is applied to analyze the presidential election data of the American Psychological Association (APA).
The depression, obstructive sleep apnea and cognitive impairment (DOC) screen assesses three post-stroke comorbidities, but additional information may be gained from the time to complete the screen. Cognitive screening completion time is rarely used as an outcome measure.
Objective:
To assess DOC screen completion time as a predictor of cognitive impairment in stroke/transient ischemic attack clinics.
Methods:
Consecutive English-speaking stroke prevention clinic patients consented to undergo screening and neuropsychological testing (n = 437). DOC screen scores and times were compared to scores on the NINDS-CSC battery using multiple linear regression (controlling for age, sex, education and stroke severity) and receiver operating characteristic (ROC) curve analysis.
Results:
Completion time for the DOC screen was 3.8 ± 1.3 minutes. After accounting for covariates, the completion time was a significant predictor of the speed of processing (p = 0.002, 95% CI: −0.016 to −0.004), verbal fluency (p < 0.001, CI: −0.012 to −0.006) and executive function (p = 0.004, CI: −0.006 to −0.001), but not memory. Completion time above 5.5 minutes was associated with a high likelihood of impairment on executive and speed of processing tasks (likelihood ratios 3.9–5.2).
Conclusions:
DOC screen completion time is easy to collect in routine care. People needing over 5.5 minutes to be screened likely have deficits in executive functioning and speed of processing – areas commonly impaired, but challenging to screen for, after stroke. DOC screen time provides a simple, feasible approach to assess these under-identified cognitive impairments.
We conduct direct numerical simulations (DNS) to study the temporal and spatial developments of the roll waves on a laminar sheet flow of Newtonian fluid. The DNS unveil the physics of the wavefront and show the limitation of the widely used shallow-layer approximations. The most prominent wave, the front runner, is determined by the DNS for the first time in studying the spatial development of the laminar sheet flow with negligible surface tension. Depending on the Froude and Reynolds numbers, the front runner can be a multi-peaked undular bore or a single-peaked non-breaking or breaking wave. The simulation has uncovered an extended region behind the wavefront, where the bed-friction stress is much higher than the corresponding friction in the undisturbed uniform flow. It also produces an uplift velocity needed in the description of wave breaking. For comparison, we also examine the nonlinear development of the instability using two-equation and four-equation shallow-layer models. The two-equation shallow-layer model has produced the bulk of the wave profile but is deficient because it fails to predict the uplift velocity and the substantial increase in bed friction in the frontal region. The four-equation shallow-layer model correctly predicts the bed friction but cannot produce the breaking wave. The simulations also determine the celerity and amplitude of the front runner to follow a linear relationship, qualitatively similar to the roll waves in a turbulent flow.
We present the Pilot Survey Phase 2 data release for the Wide-field ASKAP L-band Legacy All-sky Blind surveY (WALLABY), carried-out using the Australian SKA Pathfinder (ASKAP). We present 1760 H i detections (with a default spatial resolution of 30′′) from three pilot fields including the NGC 5044 and NGC 4808 groups as well as the Vela field, covering a total of $\sim 180$ deg$^2$ of the sky and spanning a redshift up to $z \simeq 0.09$. This release also includes kinematic models for over 126 spatially resolved galaxies. The observed median rms noise in the image cubes is 1.7 mJy per 30′′ beam and 18.5 kHz channel. This corresponds to a 5$\sigma$ H i column density sensitivity of $\sim 9.1\times10^{19}(1 + z)^4$ cm$^{-2}$ per 30′′ beam and $\sim 20$ km s$^{-1}$ channel and a 5$\sigma$ H i mass sensitivity of $\sim 5.5\times10^8 (D/100$ Mpc)$^{2}$ M$_{\odot}$ for point sources. Furthermore, we also present for the first time 12′′ high-resolution images (“cut-outs”) and catalogues for a sub-sample of 80 sources from the Pilot Survey Phase 2 fields. While we are able to recover sources with lower signal-to-noise ratio compared to sources in the Public Data Release 1, we do note that some data quality issues still persist, notably, flux discrepancies that are linked to the impact of side lobes associated with the dirty beams due to inadequate deconvolution. However, in spite of these limitations, the WALLABY Pilot Survey Phase 2 has already produced roughly a third of the number of HIPASS sources, making this the largest spatially resolved H i sample from a single survey to date.
The pale yellowish tint of usnic acid in a lichen thallus itself is a commonly used character in identification keys, particularly in the genus Cladonia. Furthermore, the presence of usnic acid is phylogenetically significant in numerous groups of lichens. While the distinctive colour of usnic acid is readily visible when present in high concentrations, it is commonly problematic to discern when in low to moderate concentrations. We explored the use of an anisaldehyde reagent for visualizing usnic acid. Using both usnic acid-containing Cladonia samples and pure usnic acid, this reaction quickly yields a bright magenta colour on HPTLC and TLC plates after heating and directly with crude acetone extracts on glass slides heated with a lighter. The same magenta product was observed whether or not the usnic acid was accompanied by barbatic, fumarprotocetraric, psoromic, squamatic or thamnolic acids, each of which alone did not produce any colour with anisaldehyde reagent. However, the merochlorophaeic acids in C. albonigra also produced a red reaction. Analysis by high resolution LC-MS of the reaction mixture between anisaldehyde and usnic acid revealed several ions at m/z 477.1586 ([M+H]+, C27H25O8) and 463.1385 ([M+H]+, C26H23O8), respectively, consistent with aldol condensation of usnic acid and p-anisaldehyde.
Although behavioral mechanisms in the association among depression, anxiety, and cancer are plausible, few studies have empirically studied mediation by health behaviors. We aimed to examine the mediating role of several health behaviors in the associations among depression, anxiety, and the incidence of various cancer types (overall, breast, prostate, lung, colorectal, smoking-related, and alcohol-related cancers).
Methods
Two-stage individual participant data meta-analyses were performed based on 18 cohorts within the Psychosocial Factors and Cancer Incidence consortium that had a measure of depression or anxiety (N = 319 613, cancer incidence = 25 803). Health behaviors included smoking, physical inactivity, alcohol use, body mass index (BMI), sedentary behavior, and sleep duration and quality. In stage one, path-specific regression estimates were obtained in each cohort. In stage two, cohort-specific estimates were pooled using random-effects multivariate meta-analysis, and natural indirect effects (i.e. mediating effects) were calculated as hazard ratios (HRs).
Results
Smoking (HRs range 1.04–1.10) and physical inactivity (HRs range 1.01–1.02) significantly mediated the associations among depression, anxiety, and lung cancer. Smoking was also a mediator for smoking-related cancers (HRs range 1.03–1.06). There was mediation by health behaviors, especially smoking, physical inactivity, alcohol use, and a higher BMI, in the associations among depression, anxiety, and overall cancer or other types of cancer, but effects were small (HRs generally below 1.01).
Conclusions
Smoking constitutes a mediating pathway linking depression and anxiety to lung cancer and smoking-related cancers. Our findings underline the importance of smoking cessation interventions for persons with depression or anxiety.
Wyoming bentonite, Fithian illite, and basalt from the Umtanum Formation, Washington, were treated hydrothermally at 200° to 460°C and 260 to 500 bars for 71 to 584 days. No change was detected for the bentonite and basalt, except for the loss of calcite and exchange of Ca for K in the smectite and the growth of a small amount of smectite (presumably from a glass phase) in the basalt. Calcite in the initial bentonite may have stabilized the smectite by Ca/K exchange; thus, if the latter is used as a packing material in a nuclear waste repository, limestone should be added. No change was detected in the illite samples treated <300°C; however, at 360°C, euhedral crystals of berthierine and illite grew at the expense of original illite/smectite, apparently by a solution-crystallization process. Significant changes involving the dissolution of starting phases and the formation of illite and chlorite were also detected in mixtures of basalt and bentonite at 400°C; at temperatures <400°C, no changes were observed.
The newly formed mineral phases (berthierine, illite, and chlorite) observed by transmission electron microscopy showed euhedral to subhedral shapes. These shapes are the same as those observed in hydrothermally altered sediments from the Salton Sea field and different from those from burial metamorphic environments, such as Gulf Coast sediments. The reaction mechanism is apparently the dissolution of reactants followed by the crystallization of products from solution, without conservation of structural elements of the reactants. Reactions apparently required temperatures greater than those for analogous changes in nature, suggesting that the degree of reaction was controlled by kinetics. The lack of dissolution in experimental runs at low temperatures, however, does not necessarily imply long-term stabilities of these clay minerals.
Facing increasing nonrenewable and environmental concerns with fossil power generation, renewable energy is being supported by government mechanisms. With the power generation cost of renewables generally higher than fossil fuels, determining the optimal level of these mechanisms requires an understanding of households’ prosocial behavior toward renewables. The issue is determining the magnitude households are willing to pay (WTP) for alternative renewables. Our hypothesis is this behavior varies by the type of renewable energy. As a test of this hypothesis, we apply a discrete choice experiment to measure households’ WTP. Results support our hypothesis with a positive WTP for solar energy, leading to a 62% reduction in solar subsidy, and a negative WTP for biomass and wind sources.
Screen time in infancy is linked to changes in social-emotional development but the pathway underlying this association remains unknown. We aim to provide mechanistic insights into this association using brain network topology and to examine the potential role of parent–child reading in mitigating the effects of screen time.
Methods
We examined the association of screen time on brain network topology using linear regression analysis and tested if the network topology mediated the association between screen time and later socio-emotional competence. Lastly, we tested if parent–child reading time was a moderator of the link between screen time and brain network topology.
Results
Infant screen time was significantly associated with the emotion processing-cognitive control network integration (p = 0.005). This network integration also significantly mediated the association between screen time and both measures of socio-emotional competence (BRIEF-2 Emotion Regulation Index, p = 0.04; SEARS total score, p = 0.04). Parent–child reading time significantly moderated the association between screen time and emotion processing-cognitive control network integration (β = −0.640, p = 0.005).
Conclusion
Our study identified emotion processing-cognitive control network integration as a plausible biological pathway linking screen time in infancy and later socio-emotional competence. We also provided novel evidence for the role of parent–child reading in moderating the association between screen time and topological brain restructuring in early childhood.
Terahertz (THz) radiation from a plasma cylinder with embedded radial electric and axial magnetic fields is investigated. The plasma density and the electric and magnetic fields are such that the electron plasma frequency is near the electron cyclotron frequency and in the THz regime. Two-dimensional particle-in-cell simulations show that the plasma electrons oscillate not only in the azimuthal direction but also in the radial direction. Spectral analysis shows that the resulting oscillating current pattern has a clearly defined characteristic frequency near the electron cyclotron frequency, suggesting resonance between the cyclotron and plasma oscillations. The resulting far-field THz radiation in the axial direction is also discussed.
Neurocognitive impairment and quality of life are two important long-term challenges for patients with complex CHD. The impact of re-interventions during adolescence and young adulthood on neurocognition and quality of life is not well understood.
Methods:
In this prospective longitudinal multi-institutional study, patients 13–30 years old with severe CHD referred for surgical or transcatheter pulmonary valve replacement were enrolled. Clinical characteristics were collected, and executive function and quality of life were assessed prior to the planned pulmonary re-intervention. These results were compared to normative data and were compared between treatment strategies.
Results:
Among 68 patients enrolled from 2016 to 2020, a nearly equal proportion were referred for surgical and transcatheter pulmonary valve replacement (53% versus 47%). Tetralogy of Fallot was the most common diagnosis (59%) and pulmonary re-intervention indications included stenosis (25%), insufficiency (40%), and mixed disease (35%). There were no substantial differences between patients referred for surgical and transcatheter therapy. Executive functioning deficits were evident in 19–31% of patients and quality of life was universally lower compared to normative sample data. However, measures of executive function and quality of life did not differ between the surgical and transcatheter patients.
Conclusion:
In this patient group, impairments in neurocognitive function and quality of life are common and can be significant. Given similar baseline characteristics, comparing changes in neurocognitive outcomes and quality of life after surgical versus transcatheter pulmonary valve replacement will offer unique insights into how treatment approaches impact these important long-term patient outcomes.
Edited by
Xiuzhen Huang, Cedars-Sinai Medical Center, Los Angeles,Jason H. Moore, Cedars-Sinai Medical Center, Los Angeles,Yu Zhang, Trinity University, Texas