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In the experiment that first demonstrated gyrotactic behaviour of bottom-heavy swimming microalgae (e.g. Chlamydomonas), Kessler (Nature, vol. 313, 1985, pp. 218–220) showed that a beam-like structure, often referred to as a gyrotactic plume, would spontaneously appear from a suspension of gyrotactic swimmers in a downflowing pipe. Such a plume is prone to an instability to form blips. This work models the gyrotactic plume as a steady parallel basic state and its subsequent breakdown into blips as an instability, employing both the generalized Taylor dispersion (GTD) theory and the Fokker–Planck model for comparison. Upon solving for the basic state, it is discovered that the steady plume solution undergoes sophisticated bifurcations. When there is no net flow, there exists a non-trivial solution of the plume structure other than the stationary uniform suspension, stemming from a transcritical bifurcation with the average cell concentration. When a net downflow is prescribed, there exists a cusp bifurcation. Furthermore, there is a critical concentration at which the cell concentration at the centre would blow up for the GTD model. The subsequent stability analysis using the steady plume solution shows that the Fokker–Planck model is inconsistent with what was experimentally observed, as it predicts stabilisation of axisymmetric blips at high concentration of the plume and destabilisation of the first non-axisymmetric mode at low flow rates.
Only a few European countries have carried out large, community-based, national surveys about psychiatric morbidity. Here is presented the first national French survey, aiming to estimate the prevalence of anxiety disorders and associated comorbidities according to sociodemographic characteristics.
Materials and methods
The Mental Health in General Population (MHGP) database is derived from a representative national survey of the French adult population (n = 36,105), conducted between 1999 and 2003. Data collection was done using an anonymous face-to-face interview. The presence of anxiety disorders (generalized anxiety disorder, panic disorder, agoraphobia, social phobia and post-traumatic stress disorder) was assessed using the Mini International Neuropsychiatric Interview.
The overall prevalence of anxiety disorders was estimated to be 21.6%, generalized anxiety disorder being the most prevalent one (12.8%). Women, young people, and people earning low income were identified as the more at risk. Major depressive episode, alcohol abuse and drug addiction frequently co-occur with anxiety disorders (28.3, 4.4 and 2.8% respectively).
The MHGP study showed that anxiety disorders are highly prevalent in France with a high frequency of comorbidities. Our results highlight the need for considering anxiety disorders as a public health priority in France as well as in other European countries.
To examine the factors that are associated with changes in depression in people with type 2 diabetes living in 12 different countries.
People with type 2 diabetes treated in out-patient settings aged 18–65 years underwent a psychiatric assessment to diagnose major depressive disorder (MDD) at baseline and follow-up. At both time points, participants completed the Patient Health Questionnaire (PHQ-9), the WHO five-item Well-being scale (WHO-5) and the Problem Areas in Diabetes (PAID) scale which measures diabetes-related distress. A composite stress score (CSS) (the occurrence of stressful life events and their reported degree of ‘upset’) between baseline and follow-up was calculated. Demographic data and medical record information were collected. Separate regression analyses were conducted with MDD and PHQ-9 scores as the dependent variables.
In total, there were 7.4% (120) incident cases of MDD with 81.5% (1317) continuing to remain free of a diagnosis of MDD. Univariate analyses demonstrated that those with MDD were more likely to be female, less likely to be physically active, more likely to have diabetes complications at baseline and have higher CSS. Mean scores for the WHO-5, PAID and PHQ-9 were poorer in those with incident MDD compared with those who had never had a diagnosis of MDD. Regression analyses demonstrated that higher PHQ-9, lower WHO-5 scores and greater CSS were significant predictors of incident MDD. Significant predictors of PHQ-9 were baseline PHQ-9 score, WHO-5, PAID and CSS.
This study demonstrates the importance of psychosocial factors in addition to physiological variables in the development of depressive symptoms and incident MDD in people with type 2 diabetes. Stressful life events, depressive symptoms and diabetes-related distress all play a significant role which has implications for practice. A more holistic approach to care, which recognises the interplay of these psychosocial factors, may help to mitigate their impact on diabetes self-management as well as MDD, thus early screening and treatment for symptoms is recommended.
Landraces (including heritage varieties) are an important agrobiodiversity resource offering considerable value as a buffer against crop failures, as a crop for niche markets, and as a source of diversity for crop genetic improvement activities underpinning future food security. Home gardens are reservoirs of landrace diversity, but some of the accessions held in them are vulnerable or threatened with extinction. Those associated with seed saving networks have added security, for example, ca. 800 varieties are stored in the Heritage Seed Library (HSL) of Garden Organic, UK. In this study, Amplified Fragment Length Polymorphisms-based genetic analysis of accessions held in the HSL was used to (a) demonstrate the range of diversity in the collection, (b) characterize accessions to aid collection management and (c) promote broader use of the collection. In total, 171 accessions were included from six crops: Vicia faba L., Pisum sativum L., Daucus carota L., Cucumis sativus L., Lactuca sativa L. and Brassica oleracea L. var. acephala (DC.) Metzq. Average expected heterozygosity ranged from 0.18 to 0.28 in D. carota; 0.02–0.18 in P. sativum; 0.05–0.18 in L. sativa; 0.15–0.26 in B. oleracea var. acephala; 0.15–0.37 in C. sativus and 0.07–0.36 in V. faba. Genetic diversity and Fst values generally reflected the breeding system and cultivation history of the different crops. Comparisons of the diversity found in heritage varieties with that found in commercial varieties did not show a consistent pattern. Principal coordinates analysis and Unweighted Pair Group Method with Arithmetic Mean cluster analysis were used to identify four potential duplicate accession pairs.
At the ANZIAM conference in Hobart in February 2018, there were several talks on the solution of Laplace problems in multiply connected domains by means of conformal mapping. It appears to be not widely known that such problems can also be solved by the elementary method of series expansions with coefficients determined by least-squares fitting on the boundary. (These are not convergent series; the coefficients depend on the degree of the approximation.) Here we give a tutorial introduction to this method, which converges at an exponential rate if the boundary data are sufficiently well-behaved. The mathematical foundations go back to Runge in 1885 and Walsh in 1929. One of our examples involves an approximate Cantor set with up to 2048 components.
We assessed evidence of exposure to viruses and bacteria in an unmanaged and long-isolated population of Soay sheep (Ovis aries) inhabiting Hirta, in the St Kilda archipelago, 65 km west of Benbecula in the Outer Hebrides of Scotland. The sheep harbour many metazoan and protozoan parasites but their exposure to viral and bacterial pathogens is unknown. We tested for herpes viral DNA in leucocytes and found that 21 of 42 tested sheep were infected with ovine herpesvirus 2 (OHV-2). We also tested 750 plasma samples collected between 1997 and 2010 for evidence of exposure to seven other viral and bacterial agents common in domestic Scottish sheep. We found evidence of exposure to Leptospira spp., with overall seroprevalence of 6·5%. However, serological evidence indicated that the population had not been exposed to border disease, parainfluenza, maedi-visna, or orf viruses, nor to Chlamydia abortus. Some sheep tested positive for antibodies against Mycobacterium avium subsp. paratuberculosis (MAP) but, in the absence of retrospective faecal samples, the presence of this infection could not be confirmed. The roles of importation, the pathogen–host interaction, nematode co-infection and local transmission warrant future investigation, to elucidate the transmission ecology and fitness effects of the few viral and bacterial pathogens on Hirta.
Attentional impairment is a core cognitive feature of major depressive disorder (MDD) and bipolar disorder (BD). However, little is known of the characteristics of response time (RT) distributions from attentional tasks. This is crucial to furthering our understanding of the profile and extent of cognitive intra-individual variability (IIV) in mood disorders.
A computerized sustained attention task was administered to 138 healthy controls and 158 patients with a mood disorder: 86 euthymic BD, 33 depressed BD and 39 medication-free MDD patients. Measures of IIV, including individual standard deviation (iSD) and coefficient of variation (CoV), were derived for each participant. Ex-Gaussian (and Vincentile) analyses were used to characterize the RT distributions into three components: mu and sigma (mean and standard deviation of the Gaussian portion of the distribution) and tau (the ‘slow tail’ of the distribution).
Compared with healthy controls, iSD was increased significantly in all patient samples. Due to minimal changes in average RT, CoV was only increased significantly in BD depressed patients. Ex-Gaussian modelling indicated a significant increase in tau in euthymic BD [Cohen's d = 0.39, 95% confidence interval (CI) 0.09–0.69, p = 0.011], and both sigma (d = 0.57, 95% CI 0.07–1.05, p = 0.025) and tau (d = 1.14, 95% CI 0.60–1.64, p < 0.0001) in depressed BD. The mu parameter did not differ from controls.
Increased cognitive variability may be a core feature of mood disorders. This is the first demonstration of differences in attentional RT distribution parameters between MDD and BD, and BD depression and euthymia. These data highlight the utility of applying measures of IIV to characterize neurocognitive variability and the great potential for future application.
Large-scale trends in planktonic foraminiferal diversity have so far been based on utilization of synoptic biostratigraphic range charts. Although this approach ensures the taxonomic consistency and quality of the data being used, it takes no formal account of any sampling biases that might exist in the fossil record. We demonstrate that the occurrence data of planktonic foraminifera, as recorded in the primary literature, are strongly biased by sampling. We do this by demonstrating that raw diversity curves derived from the land-based and deep-sea records are strikingly different, but that they each correlate with the intensity of sampling in their respective environments, and thus are ultimately controlled by the structure of the geological record in each setting. Because sampling of the Mesozoic record is best in our land record whereas sampling of the Cenozoic is best in our deep-sea record, we combine the two to generate the best-supported estimates of species and genus diversity over time from these data. We correct for sampling bias using shareholder quorum subsampling and a modeling approach. The data are then transformed to generate a range-through plot of species richness that is compared with two earlier estimates of the diversity history where comparable species-in-bin data can be recovered. No robust statistical correlation is found among the three estimates. Although differences in amplitude are to be expected, differences in the actual shape of the curve are surprising. We conclude that these differences stem from the nature of the data themselves, namely the taxonomic scheme adopted and the taxonomic coverage used.
Standard acute psychiatric care in the UK is costly but problematic. Alternatives to standard in-patient wards exist, but little is known about their effectiveness, implementation and sustainability. This paper explores successful features and limitations of five residential alternative services in England and factors that facilitate or impede their initial and sustained implementation and success.
Semi-structured interviews about the functioning of six alternative services were conducted with 36 mental health professionals with good working knowledge of, and various connections with these services. A group interview with study researchers was also conducted. Data were analysed using thematic analysis.
One service did not show evidence of operating as an alternative and was excluded from further analysis. The remaining five alternatives are valued for providing a more holistic style of care than standard services that confers many perceived benefits. However, they are seen as less appropriate for compulsorily detained or highly disturbed patients, and as providing less comprehensive treatment packages than hospital settings. Factors identified as important to successful implementation and sustainability are: responding to known shortcomings in local acute care systems; balancing role clarity and adaptability; integration with other services; and awareness of the alternative among relevant local health-care providers.
Residential alternatives can play an important role in managing mental health crises. Their successful implementation and endurance depend on establishing and maintaining a valued position within local service systems. Findings contribute to bridging the gap between research evidence on the problems of standard acute care and delivering improved crisis management services.
Assemblages of the boat-shaped bivalve Odontogryphaea thirsae (Gabb, 1861) from southwestern Alabama are used to define three ontogenetic growth stages that are bounded by major discontinuities in either mineral structure or growth-line prominence. Features of the larval and juvenile stages are described here for the first time and are compared with the well-known morphologic features that distinguish adults (late dissoconchs).
The larval stage is represented by prodissoconch valves which are about 0.4 mm in height with suborbicular outlines, commarginal striations, and ridge-like, opisthogyral beaks. The juvenile (early dissoconch) stage is expressed by dissoconch valves up to 19 mm in height with elliptical outlines (height > length), indistinct commarginal growth lines, flat commissural planes, and tiny attachment areas on left valves; the valve interiors exhibit a posterior adductor muscle scar, a resilifer, and chomata. The adult (late dissoconch) stage is characterized by dissoconch valves >19 mm in height with subtriangular outlines, prominent commarginal growth lines, wavy commissural planes, and a keel-like terebratuloid fold.
Paleonvironmental and stratigraphic studies of the diversely fossiliferous Odontogryphaea thirsae beds indicate 0. thirsae (Gabb, 1861) thrived in a shallow, normal-marine, tropical sea that extended from Texas to Georgia about 57 million years ago.
To outline methods for deriving and validating intensive care unit (ICU) antimicrobial utilization (AU) measures from computerized data and to describe programming problems that emerged.
Retrospective evaluation of computerized pharmacy and administrative data.
ICUs from 4 academic medical centers over 36 months.
Investigators separately developed and validated programming code to report AU measures in selected ICUs. Use of antibacterial and antifungal drugs for systemic administration was categorized and expressed as antimicrobial-days (each day that each antimicrobial drug was given to each patient) and patient-days receiving antimicrobials (each day that any antimicrobial drug was given to each patient). Monthly rates were compiled and analyzed centrally, with ICU patient-days as the denominator. Results were validated against data collected from manual review of medical records. Frequent discussion among investigators aided identification and correction of programming problems.
AU data were successfully programmed though a reiterative process of computer code revision. After identifying and resolving major programming errors, comparison of computerized patient-level data with data collected by manual review of medical records revealed discrepancies in antimicrobial-days and patient-days receiving antimicrobials that ranged from less than 1% to 17.7%. The hospital from which numerator data were derived from electronic records of medication administration had the least discrepant results.
Computerized AU measures can be derived feasibly, but threats to validity must be sought out and corrected. The magnitude of discrepancies between computerized AU data and a gold standard based on manual review of medical records varies, with electronic records of medication administration providing maximal accuracy.
We evaluated use of the periodically rotated overlapping parallel lines with enhanced reconstruction diffusion-weighted imaging sequence, compared with conventional echo planar magnetic resonance imaging, in the detection of middle-ear cholesteatoma.
Material and methods:
Sixteen patients awaiting second-stage combined approach tympanoplasty and three patients awaiting first-stage combined approach tympanoplasty underwent magnetic resonance imaging with both (1) the periodically rotated overlapping parallel lines with enhanced reconstruction sequence (i.e. non echo planar imaging) and (2) the array spatial sensitivity encoding technique sequence (i.e. echo planar imaging). Two neuroradiologists independently evaluated the images produced by both sequences. Radiology findings were correlated with surgical findings.
Results and analysis:
Seven cholesteatomas were found at surgery. Neither of the assessed imaging sequences were able to detect cholesteatoma of less than 4 mm. Rates for sensitivity, specificity, and positive and negative predictive values are presented.
Decisions on whether or not to operate for cholesteatoma cannot be made based on the two imaging sequences assessed, as evaluated in this study. Other contributing factors are discussed, such as the radiological learning curve and technical limitations of the magnetic resonance imaging equipment.
Key questions regarding residential alternatives to standard acute psychiatric care, such as crisis houses and short-stay in-patient units, concern the role that they fulfil within local acute care systems, and whether they manage people with needs and illnesses of comparable severity to those admitted to standard acute wards.
To study the extent to which people admitted to residential alternatives and to standard acute services are similar, and the role within local acute care systems of admission to an alternative service.
Our approach combined quantitative and qualitative methods. Consecutive cohorts of patients in six residential alternatives across England and six standard acute wards in the same areas were identified, and clinical and demographic characteristics, severity of symptoms, impairments and risks compared. Semi-structured interviews with key stakeholders in each local service system were used to explore the role and functioning of each alternative.
Being already known to services (OR = 2.6, 95% CI 1.3–5.2), posing a lower risk to others (OR = 0.49, 95% CI 0.31–0.78) and having initiated help-seeking in the current crisis (OR = 2.2, 95% CI 1.2–4.3) were associated with being admitted to an alternative rather than a standard service. Stakeholder interviews suggested that alternatives have a role that is similar but not identical to standard hospital services. They can divert some, but not all, patients from acute admission.
Residential alternatives are integrated into catchment area mental health systems. They serve similar, but not identical, clinical populations to standard acute wards and provide some, but not all, of the functions of these wards.
Differences in the content of care provided by acute in-patient mental health wards and residential crisis services such as crisis houses have not been researched.
To compare planned and actual care provided at alternative and standard acute wards and to investigate the relationship between care received and patient satisfaction.
Perspectives of stakeholders, including local service managers, clinicians and commissioners, were obtained from 23 qualitative interviews. Quantitative investigation of the care provided at four alternative and four standard services was undertaken using three instruments developed for this study. The relationship of care received to patient satisfaction was explored.
No significant difference was found in intensity of staff– patient contact between alternative and standard services. Alternative services provided more psychological and less physical and pharmacological care than standard wards. Care provision may be more collaborative and informal in alternative services. All measured types of care were positively associated with patient satisfaction. Measured differences in the care provided did not explain the greater acceptability of community alternatives.
Similarities in care may be more marked than differences at alternative and standard services. Staff–patient contact is an important determinant of patient satisfaction, so increasing it should be a priority for all acute in-patient services.
Abnormal diffusion parameters are reported in specific brain regions and white matter tracts in bipolar disorder.
To investigate whether these abnormalities are generalised, and thus evident in large regions of white matter.
Diffusion parameters were measured at several regions in the corpus callosum and in deep/periventricular white matter in 28 currently euthymic patients with bipolar disorder and controls. White matter hyperintensity loads were assessed.
Comparing the whole data-sets using the sign test, in the group with bipolar disorder, mean diffusivity was greater at all 15 sites (P<0.001) and fractional anisotropy was reduced at 13 (P<0.01). The effect of diagnosis was significant for callosal mean diffusivity and fractional anisotropy and for deep/periventricular mean diffusivity (MANCOVA). Comparing individual regions (Mann–Whitney U-test), prefrontal and periventricular mean diffusivity were significantly increased; callosal and occipital fractional anisotropy were significantly reduced. Former substance use and lithium were possible confounding factors. Periventricular white matter hyperintensities were associated with significantly increased periventricular mean diffusivity in individuals with bipolar disorder.
Generalised white matter microstructural abnormalities may exist in bipolar disorder, possibly exacerbated by past substance use and ameliorated by lithium.
We compared the results of the tuberculin skin test with the results of the QuantiFERON-TB Gold In-Tube (QFT-GIT) assay among 182 low-risk healthcare workers. Overall agreement and specificity were high, but the tests did not agree on positive results. Only 2 of 5 positive QFT-GIT assay results could be confirmed with repeat analyses. Indeterminate results were associated with potential immunosuppression.