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Catatonia has many potential underlying causes, but in some patients, no clear etiology is identified, sparking growing interest in its genetic basis. We aimed to provide the first comprehensive synthesis of genetic abnormalities in catatonia.
Methods
In this systematic review (PROSPERO CRD42023455118) we searched MEDLINE All, Embase Classic + Embase, PsycINFO, and AMED up to August 15, 2023, for studies on genetic testing and catatonia phenotyping in all age groups. Catatonia was diagnosed using specified diagnostic criteria or description of clinical features. Risk of bias was assessed using the Joanna Briggs Institute quality assessment tools. Results were summarized with a narrative synthesis.
Results
We included 99 studies involving 8600 individuals. Sex was reported for 6080 individuals, of whom 3208 (52.8%) were male. Mean age at onset of catatonia was 28.8 years (SD 16.3). The median duration of the index catatonic episode was 180 days (IQR 38 to 668). Stupor and mutism were the most frequently reported symptoms. Forty-seven genetic conditions were reported in catatonia, including Phelan-McDermid syndrome (n = 80), 22q11.2 deletion syndrome (n = 23), and Down’s syndrome (n = 19). Study quality was good in 29 studies, moderate in 53, and poor in 17. The major focus of association studies has centered on periodic catatonia; despite identifying candidate genes at both 22q13 and 15q15, none have been replicated.
Conclusions
Catatonia can manifest in a wide range of genetic syndromes, suggesting a shared vulnerability across diverse genetic and developmental disorders. We did not identify a unique phenomenology or treatment response profile in genetic associations of catatonia.
Neuropsychiatry training in the UK currently lacks a formal scheme or qualification, and its demand and availability have not been systematically explored. We conducted the largest UK-wide survey of psychiatry trainees to examine their experiences in neuropsychiatry training.
Results
In total, 185 trainees from all UK training regions completed the survey. Although 43.6% expressed interest in a neuropsychiatry career, only 10% felt they would gain sufficient experience by the end of training. Insufficient access to clinical rotations was the most common barrier, with significantly better access in London compared with other regions. Most respondents were in favour of additional neurology training (83%) and a formal accreditation in neuropsychiatry (90%).
Clinical implications
Strong trainee interest in neuropsychiatry contrasts with the limited training opportunities currently available nationally. Our survey highlights the need for increased neuropsychiatry training opportunities, development of a formalised training programme and a clinical accreditation pathway for neuropsychiatry in the UK.
Treatment for pediatric brain tumors (PBTs) is associated with neurocognitive risk, including declines in IQ, executive function, and visual motor processing. Low grade tumors require less intensive treatment (i.e., focal radiotherapy (RT) or surgical resection alone), and have been associated with more favorable cognitive outcomes. However, these patients remain at risk of cognitive problems, which may present differently depending on tumor location. Executive functioning (EF), in particular, has been broadly associated with both frontal-subcortical networks (supratentorial) and the cerebellum (infratentorial). The current study examined intellectual functioning, executive functioning (set-shifting and inhibition), and visual motor skills in patients who were treated for low-grade tumors located in either the supratentorial or infratentorial region.
Participants and Methods:
Participants were survivors (age 8-18) previously treated with focal proton RT or surgery alone for infratentorial (n=21) or supratentorial (n=34) low grade glioma (83.6%) or low grade glioneuronal tumors (16.4%). Survivors >2.5 years post-treatment completed cognitive testing (WISC-IV/WAIS-IV; D-KEFS Verbal Fluency (VF), Color-Word Interference (CW), Trail Making Test (TM); Beery Visual-Motor Integration). We compared outcomes between infratentorial and supratentorial groups using analysis of covariance (ANCOVA). Demographic and clinical variables were compared using Welch’s t-tests. ANCOVAs were adjusted for age at evaluation, age at treatment, and history of posterior fossa syndrome due to significant or marginally significant differences between groups.
Results:
Tumor groups did not significantly differ with respect to sex (49.0% male), length of follow-up (M 4.4 years), or treatment type (74.5% surgery alone, 25.5% proton RT). Marginally significant group differences were found for age at evaluation (infratentorial M = 12.4y, supratentorial M = 14.1y, p = .054) and age at treatment (infratentorial M = 7.9y, supratentorial M = 9.7y, p =.074). Posterior fossa syndrome only occurred with infratentorial tumors (n=5, p = .003). Adjusting for covariates, the supratentorial group exhibited significantly superior performance on a measure of inhibition and set-shifting (CW Switching Time (t(32) = -2.05, p=.048, n2 =.11). There was a marginal group difference in the same direction on CW Inhibition Time (t(32 = -1.77, p = .086, n2 =.08). On the other hand, the supratentorial group showed significantly lower working memory than the infratentorial group (t(50) = 2.45, p = .018, n2 = .11), and trends toward lower verbal reasoning (t(50)=1.96, p = .056, n2 = .07) and full-scale IQ (t(50)=1.73, p = .090, n2 = .055). No other group differences were identified across intellectual, EF, and visualmotor measures.
Conclusions:
Infratentorial tumor location was associated with weaker switching and inhibition performance, while supratentorial tumor location was associated with lower performance on intellectual measures, particularly working memory. These findings suggest that even with relatively conservative treatment (i.e., focal proton RT or surgery alone), there remains neurocognitive risk in children treated for low-grade brain tumors. Moreover, tumor location may predict distinct patterns of long-term neurocognitive outcomes, depending on which brain networks are involved.
Individual hosts are often co-infected with multiple parasite species. Evidence from theoretical and empirical studies supports the idea that co-occurring parasites can impact each other and their hosts via synergistic or antagonistic interactions. The fundamental aim of understanding the consequences of co-infection to hosts and parasites requires an understanding of patterns of species co-occurrence within samples of hosts. We censused parasite assemblages in 755 adult, male fathead minnows collected from 7 lakes/ponds in southern Alberta, Canada between 2018 and 2020. Fifteen species of endoparasites infected fathead minnows, 98% of which were co-infected with between 2 and 9 parasite species (mean species richness: 4.4 ± 1.4). Non-random pairwise associations were detected within the overall parasite community. There were particularly strong, positive associations in the occurrences and intensities of the 2 congeneric larval trematodes Ornithodiplostomum sp. and Ornithodiplostomum ptychocheilus that comprised >96% of the 100 000+ parasites counted in the total sample of minnows. Furthermore, the occurrence of Ornithodiplostomum sp. was a strong predictor of the occurrence of O. ptychocheilus, and vice versa. Positive covariation in the intensities of these 2 dominants likely arises from their shared use of physid snails as first intermediate hosts in these waterbodies. These 2 species represent a predictable and non-random component within the complex assemblage of parasites of fathead minnows in this region.
The Australian SKA Pathfinder (ASKAP) radio telescope has carried out a survey of the entire Southern Sky at 887.5 MHz. The wide area, high angular resolution, and broad bandwidth provided by the low-band Rapid ASKAP Continuum Survey (RACS-low) allow the production of a next-generation rotation measure (RM) grid across the entire Southern Sky. Here we introduce this project as Spectral and Polarisation in Cutouts of Extragalactic sources from RACS (SPICE-RACS). In our first data release, we image 30 RACS-low fields in Stokes I, Q, U at 25$^{\prime\prime}$ angular resolution, across 744–1032 MHz with 1 MHz spectral resolution. Using a bespoke, highly parallelised, software pipeline we are able to rapidly process wide-area spectro-polarimetric ASKAP observations. Notably, we use ‘postage stamp’ cutouts to assess the polarisation properties of 105912 radio components detected in total intensity. We find that our Stokes Q and U images have an rms noise of $\sim$80 $\unicode{x03BC}$Jy PSF$^{-1}$, and our correction for instrumental polarisation leakage allows us to characterise components with $\gtrsim$1% polarisation fraction over most of the field of view. We produce a broadband polarised radio component catalogue that contains 5818 RM measurements over an area of $\sim$1300 deg$^{2}$ with an average error in RM of $1.6^{+1.1}_{-1.0}$ rad m$^{-2}$, and an average linear polarisation fraction $3.4^{+3.0}_{-1.6}$ %. We determine this subset of components using the conditions that the polarised signal-to-noise ratio is $>$8, the polarisation fraction is above our estimated polarised leakage, and the Stokes I spectrum has a reliable model. Our catalogue provides an areal density of $4\pm2$ RMs deg$^{-2}$; an increase of $\sim$4 times over the previous state-of-the-art (Taylor, Stil, Sunstrum 2009, ApJ, 702, 1230). Meaning that, having used just 3% of the RACS-low sky area, we have produced the 3rd largest RM catalogue to date. This catalogue has broad applications for studying astrophysical magnetic fields; notably revealing remarkable structure in the Galactic RM sky. We will explore this Galactic structure in a follow-up paper. We will also apply the techniques described here to produce an all-Southern-sky RM catalogue from RACS observations. Finally, we make our catalogue, spectra, images, and processing pipeline publicly available.
We examine interest group involvement in Supreme Court nominations from 1930 to 2017, finding dramatic shifts in the number and type of groups, as well as their choice of tactics. Whereas the early period was dominated by labor unions, “core” civil rights groups, and groups affiliated with the “old right,” the modern period is dominated by public interest/citizen groups and “identity” groups. We also find a shift from more traditional “inside” tactics to the heavy use of “outside/grassroots” mobilization tactics. Finally, we show that the calculus of mobilization has increasingly been based on a nominee’s ideology over time.
A standardised multi-site approach to manage paediatric post-operative chylothorax does not exist and leads to unnecessary practice variation. The Chylothorax Work Group utilised the Pediatric Critical Care Consortium infrastructure to address this gap.
Methods:
Over 60 multi-disciplinary providers representing 22 centres convened virtually as a quality initiative to develop an algorithm to manage paediatric post-operative chylothorax. Agreement was objectively quantified for each recommendation in the algorithm by utilising an anonymous survey. “Consensus” was defined as ≥ 80% of responses as “agree” or “strongly agree” to a recommendation. In order to determine if the algorithm recommendations would be correctly interpreted in the clinical environment, we developed ex vivo simulations and surveyed patients who developed the algorithm and patients who did not.
Results:
The algorithm is intended for all children (<18 years of age) within 30 days of cardiac surgery. It contains rationale for 11 central chylothorax management recommendations; diagnostic criteria and evaluation, trial of fat-modified diet, stratification by volume of daily output, timing of first-line medical therapy for “low” and “high” volume patients, and timing and duration of fat-modified diet. All recommendations achieved “consensus” (agreement >80%) by the workgroup (range 81–100%). Ex vivo simulations demonstrated good understanding by developers (range 94–100%) and non-developers (73%–100%).
Conclusions:
The quality improvement effort represents the first multi-site algorithm for the management of paediatric post-operative chylothorax. The algorithm includes transparent and objective measures of agreement and understanding. Agreement to the algorithm recommendations was >80%, and overall understanding was 94%.
While longstanding theories of political behavior argue that voters do not possess sufficient political knowledge to hold their elected representatives accountable, recent revisionist studies challenge this view, arguing that voters can both follow how their representatives vote and use that information intelligently. We apply the revisionist account to the study of Supreme Court nominations in the modern era. Using survey data on the nominations of Clarence Thomas, Sonia Sotomayor, and Elena Kagan, we ask whether voters can and do hold senators accountable for their votes on Supreme Court nominees. While our results for Thomas are ambiguous, we find strong evidence for accountability in the cases of Sotomayor and Kagan. In particular, we show that voters on average can correctly recall the votes of their senators on these nominees, and that correct recall is correlated with higher levels of education and political knowledge. We then show that voters are more likely to both approve of and vote to re-elect their senator if he or she casts a vote on Sotomayor and Kagan that is in line with voters’ preferences. Finally, we show this effect is quite sizable, as it rivals the effect of agreement on other high-profile roll call votes. These results have important implications for both the broader study of representation and for understanding the current politics of Supreme Court nominations.
The potential antidepressant properties of probiotics have been suggested, but their influence on the emotional processes that may underlie this effect is unclear.
Methods
Depressed volunteers (n = 71) were recruited into a randomised double-blind, placebo-controlled study to explore the effects of a daily, 4-week intake of a multispecies probiotic or placebo on emotional processing and cognition. Mood, anxiety, positive and negative affect, sleep, salivary cortisol and serum C-reactive peptide (CRP) were assessed before and after supplementation.
Results
Compared with placebo, probiotic intake increased accuracy at identifying faces expressing all emotions (+12%, p < 0.05, total n = 51) and vigilance to neutral faces (mean difference between groups = 12.28 ms ± 6.1, p < 0.05, total n = 51). Probiotic supplementation also reduced reward learning (−9%, p < 0.05, total n = 51), and interference word recall on the auditory verbal learning task (−18%, p < 0.05, total n = 50), but did not affect other aspects of cognitive performance. Although actigraphy revealed a significant group × night-time activity interaction, follow up analysis was not significant (p = 0.094). Supplementation did not alter salivary cortisol or circulating CRP concentrations. Probiotic intake significantly reduced (−50% from baseline, p < 0.05, n = 35) depression scores on the Patient Health Questionnaire-9, but these did not correlate with the changes in emotional processing.
Conclusions
The impartiality to positive and negative emotional stimuli or reward after probiotic supplementation have not been observed with conventional antidepressant therapies. Further studies are required to elucidate the significance of these changes with regard to the mood-improving action of the current probiotic.
Approximately one in ten adults under the age of 65 in the USA has a mobility impairing disability. People with mobility impairment generally have poorer dietary habits contributing to obesity and related negative health outcomes. This article presents the psychometric properties of the Food Environment Assessment Survey Tool (FEAST) instrument that measures barriers to accessing healthy food from the perspective of people with mobility impairment (PMI).
Design:
The current study presents cross-sectional data from two sequential independent surveys.
Setting:
Surveys were administered online to a national sample of PMI.
Participants:
Participants represented PMI living throughout the USA. The pilot FEAST survey involved 681 participants and was used to shape the final instrument; 25 % completed a retest survey. After following empirically and theoretically guided item reduction strategies, the final FEAST instrument was administered to a separate sample of 304 PMI.
Results:
The final twenty-seven-item FEAST instrument includes items measuring Neighbourhood Environment, Home Environment, Personal Control and Access to Support (Having Help, Food Delivery Services, Parking/Transportation). The final four scales had acceptable intra-class correlations, indicating that the scales could be used as reliable measures of the hypothesised constructs in future studies.
Conclusions:
The FEAST instrument is the first of its kind developed to assess the food environment from the perspective of PMI themselves. Future studies would benefit from using this measure in research and practice to help guide the development of policy aimed at improving access to healthy food and promoting healthy eating in community-dwelling PMI.
Although research has shown that exposure to potentially traumatic and morally injurious events is associated with psychological symptoms among veterans, knowledge regarding functioning impacts remains limited.
Methods
A population-based sample of post-9/11 veterans completed measures of intimate relationship, health, and work functioning at approximately 9, 15, 21, and 27 months after leaving service. Moral injury, posttraumatic stress, and depression were assessed at ~9 months post-separation. We used Latent Growth Mixture Models to identify discrete classes characterized by unique trajectories of change in functioning over time and to examine predictors of class membership.
Results
Veterans were assigned to one of four functioning trajectories: high and stable, high and decreasing, moderate and increasing, and moderate and stable. Whereas posttraumatic stress, depression, and moral injury associated with perpetration and betrayal predicted worse outcomes at baseline across multiple functioning domains, moral injury associated with perpetration and depression most reliably predicted assignment to trajectories characterized by relatively poor or declining functioning.
Conclusions
Moral injury contributes to functional problems beyond what is explained by posttraumatic stress and depression, and moral injury due to perpetration and depression most reliably predicted assignment to trajectories characterized by functional impairment over time.
Children and young people with intellectual disability and/or Autism Spectrum Disorder (autism) experience higher rates of mental health problems, including depression, than their typically developing peers. Although international guidelines suggest psychological therapies as first-line intervention for children and young people, there is limited evidence for psychological therapy for depression in children and young people with intellectual disability and/or autism.
Aims
To evaluate the current evidence base for psychological interventions for depression in children and young people with intellectual disability and/or autism, and examine the experiences of children and young people with intellectual disability and/or autism, their families and therapists, in receiving and delivering psychological treatment for depression.
Method
Databases were searched up to 30 April 2020 using pre-defined search terms and criteria. Articles were independently screened and assessed for risk of bias. Data were synthesised and reported in a narrative review format.
Results
A total of 10 studies met the inclusion criteria. Four identified studies were clinical case reports and six were quasi-experimental or experimental studies. All studies were assessed as being of moderate or high risk of bias. Participants with intellectual disability were included in four studies. There was limited data on the experiences of young people, their families or therapists in receiving or delivering psychological treatment for depression.
Conclusions
Well-designed, randomised controlled trials are critical to develop an evidence base for psychological treatment for young people with intellectual disability and/or autism with depression. Future research should evaluate the treatment experiences of young people, their families and therapists.
Gravitational waves from coalescing neutron stars encode information about nuclear matter at extreme densities, inaccessible by laboratory experiments. The late inspiral is influenced by the presence of tides, which depend on the neutron star equation of state. Neutron star mergers are expected to often produce rapidly rotating remnant neutron stars that emit gravitational waves. These will provide clues to the extremely hot post-merger environment. This signature of nuclear matter in gravitational waves contains most information in the 2–4 kHz frequency band, which is outside of the most sensitive band of current detectors. We present the design concept and science case for a Neutron Star Extreme Matter Observatory (NEMO): a gravitational-wave interferometer optimised to study nuclear physics with merging neutron stars. The concept uses high-circulating laser power, quantum squeezing, and a detector topology specifically designed to achieve the high-frequency sensitivity necessary to probe nuclear matter using gravitational waves. Above 1 kHz, the proposed strain sensitivity is comparable to full third-generation detectors at a fraction of the cost. Such sensitivity changes expected event rates for detection of post-merger remnants from approximately one per few decades with two A+ detectors to a few per year and potentially allow for the first gravitational-wave observations of supernovae, isolated neutron stars, and other exotica.
Diet has a major influence on the composition and metabolic output of the gut microbiome. Higher-protein diets are often recommended for older consumers; however, the effect of high-protein diets on the gut microbiota and faecal volatile organic compounds (VOC) of elderly participants is unknown. The purpose of the study was to establish if the faecal microbiota composition and VOC in older men are different after a diet containing the recommended dietary intake (RDA) of protein compared with a diet containing twice the RDA (2RDA). Healthy males (74⋅2 (sd 3⋅6) years; n 28) were randomised to consume the RDA of protein (0⋅8 g protein/kg body weight per d) or 2RDA, for 10 weeks. Dietary protein was provided via whole foods rather than supplementation or fortification. The diets were matched for dietary fibre from fruit and vegetables. Faecal samples were collected pre- and post-intervention for microbiota profiling by 16S ribosomal RNA amplicon sequencing and VOC analysis by head space/solid-phase microextraction/GC-MS. After correcting for multiple comparisons, no significant differences in the abundance of faecal microbiota or VOC associated with protein fermentation were evident between the RDA and 2RDA diets. Therefore, in the present study, a twofold difference in dietary protein intake did not alter gut microbiota or VOC indicative of altered protein fermentation.
In response to advancing clinical practice guidelines regarding concussion management, service members, like athletes, complete a baseline assessment prior to participating in high-risk activities. While several studies have established test stability in athletes, no investigation to date has examined the stability of baseline assessment scores in military cadets. The objective of this study was to assess the test–retest reliability of a baseline concussion test battery in cadets at U.S. Service Academies.
Methods:
All cadets participating in the Concussion Assessment, Research, and Education (CARE) Consortium investigation completed a standard baseline battery that included memory, balance, symptom, and neurocognitive assessments. Annual baseline testing was completed during the first 3 years of the study. A two-way mixed-model analysis of variance (intraclass correlation coefficent (ICC)3,1) and Kappa statistics were used to assess the stability of the metrics at 1-year and 2-year time intervals.
Results:
ICC values for the 1-year test interval ranged from 0.28 to 0.67 and from 0.15 to 0.57 for the 2-year interval. Kappa values ranged from 0.16 to 0.21 for the 1-year interval and from 0.29 to 0.31 for the 2-year test interval. Across all measures, the observed effects were small, ranging from 0.01 to 0.44.
Conclusions:
This investigation noted less than optimal reliability for the most common concussion baseline assessments. While none of the assessments met or exceeded the accepted clinical threshold, the effect sizes were relatively small suggesting an overlap in performance from year-to-year. As such, baseline assessments beyond the initial evaluation in cadets are not essential but could aid concussion diagnosis.
Introduction: Trauma care is highly complex and prone to medical errors. Accordingly, several studies have identified adverse events and conditions leading to potentially preventable or preventable deaths. Depending on the availability of specialized trauma care and the trauma system organization, between 10 and 30% of trauma-related deaths worldwide could be preventable if optimal care was promptly delivered. This narrative review aims to identify the main determinants and areas for improvements associated with potentially preventable trauma mortality. Methods: A literature review was performed using Medline, Embase and Cochrane Central Register of Controlled Trials from 1990 to a maximum of 6 months before submission for publication. Experimental or observational studies that have assessed determinants and areas for improvements that are associated with trauma death preventability were considered for inclusion. Two researchers independently selected eligible studies and extracted the relevant data. The main areas for improvements were classified using the Joint Commission on Accreditation of Healthcare Organizations patient event taxonomy. No statistical analyses were performed given the data heterogeneity. Results: From the 3647 individual titles obtained by the search strategy, a total of 37 studies were included. Each study included between 72 and 35311 trauma patients who had sustained mostly blunt trauma, frequently following a fall or a motor vehicle accident. Preventability assessment was performed for 17 to 2081 patients using either a single expert assessment (n = 2, 5,4%) or an expert panel review (n = 35, 94.6%). The definition of preventability and the taxonomy used varied greatly between the studies. The rate of potentially preventable or preventable death ranged from 2.4% to 76.5%. The most frequently reported areas for improvement were treatment delay, diagnosis accuracy to avoid missed or incorrect diagnosis and adverse events associated with the initial procedures performed. The risk of bias of the included studies was high for 32 studies because of the retrospective design and the panel review preventability assessment. Conclusion: Deaths occurring after a trauma remain often preventable. Included studies have used unstandardized definitions of a preventable death and various methodologies to perform the preventability assessment. The proportion of preventable or potentially preventable death reported in each study ranged from 2.4% to 76.5%. Delayed treatment, missed or incorrect initial diagnosis and adverse events following a procedure were commonly associated with preventable trauma deaths and could be targeted to develop quality improvement and monitoring projects.
Skeletal muscle is integral to the metabolism and utilisation of macronutrients; however, substantial muscle loss and morphological changes occur with ageing. These are associated with loss of muscle function and accelerate rapidly from the age of 60 years, leading to the conditions of sarcopenia and frailty. As the relationship between muscle ageing and macronutrient metabolism and utilisation has seen limited research to date, this review focuses on the interactions between skeletal muscle changes during ageing, metabolism and utilisation of fat, carbohydrates and overall energy expenditure.
Skeletal muscle contributes less to resting energy expenditure during ageing, potentially contributing to onset of obesity from middle age. Age-related changes to skeletal muscle lead to glucose dysregulation, with consequent reduction in glycaemic control, increased insulin resistance and ultimately onset of type-2 diabetes. Recent studies indicate that high total fat and SFA intake are detrimental to skeletal muscle, while higher intakes of PUFA are protective. Age-associated changes in skeletal muscle may also reduce total fatty acid utilisation.
In conclusion, further research is needed to understand the relationships between macronutrient metabolism and utilisation and age-related changes to skeletal muscle. No dietary recommendations exist specifically for skeletal muscle health during ageing, but we advise individuals to follow healthy eating guidelines, by consuming sufficient protein, fruit and vegetables, and limited SFA and to maintain physically active lifestyles. Clinicians responsible for managing type-2 diabetes need to be aware of growing evidence relating age-related skeletal muscle changes to diabetes onset and progression.
The nearby Magellanic Clouds system covers more than 200 square degrees on the sky. Much of it has been mapped across the electromagnetic spectrum at high angular resolution and sensitivity –X-ray (XMM-Newton), UV (UVIT), optical (SMASH), IR (VISTA, WISE, Spitzer, Herschel), radio (ATCA, ASKAP, MeerKAT). This provides us with an excellent dataset to explore the galaxy populations behind the stellar-rich Magellanic Clouds. We seek to identify and characterise AGN via machine learning algorithms on this exquisite data set. Our project focuses not on establishing sequences and distributions of common types of galaxies and active galactic nuclei (AGN), but seeks to identify extreme examples, building on the recent accidental discoveries of unique AGN behind the Magellanic Clouds.
A theoretically based relationship for the Darcy–Weisbach friction factor $f$ for rough-bed open-channel flows is derived and discussed. The derivation procedure is based on the double averaging (in time and space) of the Navier–Stokes equation followed by repeated integration across the flow. The obtained relationship explicitly shows that the friction factor can be split into at least five additive components, due to: (i) viscous stress; (ii) turbulent stress; (iii) dispersive stress (which in turn can be subdivided into two parts, due to bed roughness and secondary currents); (iv) flow unsteadiness and non-uniformity; and (v) spatial heterogeneity of fluid stresses in a bed-parallel plane. These constitutive components account for the roughness geometry effect and highlight the significance of the turbulent and dispersive stresses in the near-bed region where their values are largest. To explore the potential of the proposed relationship, an extensive data set has been assembled by employing specially designed large-eddy simulations and laboratory experiments for a wide range of Reynolds numbers. Flows over self-affine rough boundaries, which are representative of natural and man-made surfaces, are considered. The data analysis focuses on the effects of roughness geometry (i.e. spectral slope in the bed elevation spectra), relative submergence of roughness elements and flow and roughness Reynolds numbers, all of which are found to be substantial. It is revealed that at sufficiently high Reynolds numbers the roughness-induced and secondary-currents-induced dispersive stresses may play significant roles in generating bed friction, complementing the dominant turbulent stress contribution.