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"Kaminski, A"
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Stratified shear instability in a field of pre-existing turbulence
Turbulent mixing of heat and momentum in the stably-stratified ocean interior occurs in discrete events driven by vertical variations of the horizontal velocity. Typically, these events have been modelled assuming an initially laminar stratified shear flow which develops wavelike instabilities, becomes fully turbulent, and then relaminarizes into a stable state. However, in the real ocean there is always some level of turbulence left over from previous events. Using direct numerical simulations, we show that the evolution of a stably-stratified shear layer may be significantly modified by pre-existing turbulence. The classical billow structure associated with Kelvin–Helmholtz instability is suppressed and eventually eliminated as the strength of the initial turbulence is increased. A corresponding energetics analysis shows that potential energy changes and dissipation of kinetic energy depend non-monotonically on initial turbulence strength, with the largest effects when initial turbulence is present but insufficient to prevent billow formation. The mixing efficiency decreases with increasing initial turbulence amplitude as the development of the Kelvin–Helmholtz billow, with its large pre-turbulent mixing efficiency, is arrested.
Journal Article
Nickelodeon pandemonium! 1, Channeling fun
Collects eleven stories featuring the stars of Nickelodeon, including Sanjay and Craig, Pig, Boat, Banana, and Cricket, and Fee and Foo.
Book
The year 2010 classification of the agglutinated foraminifera
A reclassification of the agglutinated foraminifera (within the Class Foraminiferea) is presented, consisting of three subclasses, seven orders, 18 suborders, 32 superfamilies, 122 families, 148 subfamilies, and containing a total of 832 valid genera is presented. The classification is modified from the suprageneric scheme used by Kaminski (2004a), and incorporates all the new agglutinated genera described up to and including the year 2010. The major differences from the Kaminski (2004a) classification are (1) the subdivision of the Foraminifera into three supraordinal groups according to the molecular studies of Pawłowski and co-workers (2) the inclusion of the allogromiids in the classification alongside the astrorhizids (3) the inclusion of the xenophyophorids within the Astrorhizida at superfamily rank, (4) the merging of all pseudo-bilocular and pseudo-multichambered forms within a single subclass and (5) the revision of the schlumberigerinids to encompass all miliolids with an agglutinated wall. Numerous minor corrections and updates have been made to the generic classification based on the recent literature.
Journal Article
Suicide risk with selective serotonin reuptake inhibitors and other new-generation antidepressants in adults: a systematic review and meta-analysis of observational studies
BackgroundThere is ongoing controversy whether antidepressant use alters suicide risk in adults with depression and other treatment indications.MethodsSystematic review of observational studies, searching MEDLINE, PsycINFO, Web of Science, PsycARTICLES and SCOPUS for case–control and cohort studies. We included studies on depression and various indications unspecified (including off-label use) reporting risk of suicide and/or suicide attempt for adult patients using selective serotonin reuptake inhibitors (SSRI) and other new-generation antidepressants relative to non-users. Effects were meta-analytically aggregated with random-effects models, reporting relative risk (RR) estimates with 95% CIs. Publication bias was assessed via funnel-plot asymmetry and trim-and-fill method. Financial conflict of interest (fCOI) was defined present when lead authors’ professorship was industry-sponsored, they received industry-payments, or when the study was industry-sponsored.ResultsWe included 27 studies, 19 on depression and 8 on various indications unspecified (n=1.45 million subjects). SSRI were not definitely related to suicide risk (suicide and suicide attempt combined) in depression (RR=1.03, 0.70–1.51) and all indications (RR=1.19, 0.88–1.60). Any new-generation antidepressant was associated with higher suicide risk in depression (RR=1.29, 1.06–1.57) and all indications (RR=1.45, 1.23–1.70). Studies with fCOI reported significantly lower risk estimates than studies without fCOI. Funnel-plots were asymmetrical and imputation of missing studies with trim-and-fill method produced considerably higher risk estimates.ConclusionsExposure to new-generation antidepressants is associated with higher suicide risk in adult routine-care patients with depression and other treatment indications. Publication bias and fCOI likely contribute to systematic underestimation of risk in the published literature.RegistrationOpen Science Framework, https://osf.io/eaqwn/
Journal Article
Advances in Human B Cell Phenotypic Profiling
To advance our understanding and treatment of disease, research immunologists have been called-upon to place more centralized emphasis on impactful human studies. Such endeavors will inevitably require large-scale study execution and data management regulation (\"Big Biology\"), necessitating standardized and reliable metrics of immune status and function. A well-known example setting this large-scale effort in-motion is identifying correlations between eventual disease outcome and T lymphocyte phenotype in large HIV-patient cohorts using multiparameter flow cytometry. However, infection, immunodeficiency, and autoimmunity are also characterized by correlative and functional contributions of B lymphocytes, which to-date have received much less attention in the human Big Biology enterprise. Here, we review progress in human B cell phenotyping, analysis, and bioinformatics tools that constitute valuable resources for the B cell research community to effectively join in this effort.
Journal Article
Methods for Assessing the Effectiveness of Modern Counter Unmanned Aircraft Systems
Given the growing threat posed by the widespread availability of unmanned aircraft systems (UASs), which can be utilised for various unlawful activities, the need for a standardised method to evaluate the effectiveness of systems capable of detecting, tracking, and identifying (DTI) these devices has become increasingly urgent. This article draws upon research conducted under the European project COURAGEOUS, where 260 existing drone detection systems were analysed, and a methodology was developed for assessing the suitability of C-UASs in relation to specific threat scenarios. The article provides an overview of the most commonly employed technologies in C-UASs, such as radars, visible light cameras, thermal imaging cameras, laser range finders (lidars), and acoustic sensors. It explores the advantages and limitations of each technology, highlighting their reliance on different physical principles, and also briefly touches upon the legal implications associated with their deployment. The article presents the research framework and provides a structural description, alongside the functional and performance requirements, as well as the defined metrics. Furthermore, the methodology for testing the usability and effectiveness of individual C-UAS technologies in addressing specific threat scenarios is elaborated. Lastly, the article offers a concise list of prospective research directions concerning the analysis and evaluation of these technologies.
Journal Article
Transient growth in strongly stratified shear layers
We investigate numerically transient linear growth of three-dimensional perturbations in a stratified shear layer to determine which perturbations optimize the growth of the total kinetic and potential energy over a range of finite target time intervals. The stratified shear layer has an initial parallel hyperbolic tangent velocity distribution with Reynolds number
$\\def \\xmlpi #1{}\\def \\mathsfbi #1{\\boldsymbol {\\mathsf {#1}}}\\let \\le =\\leqslant \\let \\leq =\\leqslant \\let \\ge =\\geqslant \\let \\geq =\\geqslant \\def \\Pr {\\mathit {Pr}}\\def \\Fr {\\mathit {Fr}}\\def \\Rey {\\mathit {Re}}\\mathit{Re}=U_0 h/\\nu =1000$
and Prandtl number
$\\nu /\\kappa =1$
, where
$\\nu $
is the kinematic viscosity of the fluid and
$\\kappa $
is the diffusivity of the density. The initial stable buoyancy distribution has constant buoyancy frequency
$N_0$
, and we consider a range of flows with different bulk Richardson number
${\\mathit{Ri}}_b=N_0^2h^2/U_0^2$
, which also corresponds to the minimum gradient Richardson number
${\\mathit{Ri}}_g(z)=N_0^2/(\\mathrm{d}U/\\mathrm{d} z)^2$
at the midpoint of the shear layer. For short target times, the optimal perturbations are inherently three-dimensional, while for sufficiently long target times and small
${\\mathit{Ri}}_b$
the optimal perturbations are closely related to the normal-mode ‘Kelvin–Helmholtz’ (KH) instability, consistent with analogous calculations in an unstratified mixing layer recently reported by Arratia et al. (J. Fluid Mech., vol. 717, 2013, pp. 90–133). However, we demonstrate that non-trivial transient growth occurs even when the Richardson number is sufficiently high to stabilize all normal-mode instabilities, with the optimal perturbation exciting internal waves at some distance from the midpoint of the shear layer.
Journal Article
The impact of specific pulmonary arterial hypertension therapy on cardiac fluorodeoxyglucose distribution in PET/MRI hybrid imaging–follow-up study
BackgroundPET/MRI hybrid imaging in pulmonary arterial hypertension (PAH) provides important prognostic information identifying patients who might benefit from early therapy escalation, as right ventricle (RV) metabolic alterations are linked with hemodynamics and might precede clinical deterioration. Now, we hypothesize that adequate PAH therapy escalation may result in reversal of unfavourable increased glucose uptake of RV, which is associated with improved prognosis. MethodsOut of twenty-six initially clinically stable PAH patients who had baseline PET/MRI scans, twenty (49.9 ± 14.9 years) had second PET/MRI after 24 months. SUVRV/SUVLV ratio was used to estimate and compare cardiac glucose uptake. Occurrences of clinical endpoints (CEP), defined as death or clinical deterioration, were assessed during 48-month follow-up from baseline.ResultsIn first 24 months of observation, sixteen patients had CEP and needed PAH therapy escalation. At follow-up visits, we observed significant improvement of RV ejection fraction (45.1 ± 9.6% to 52.4 ± 12.9%, p = 0.01), mean pulmonary artery pressure (50.5 ± 18.3 to 42.8 ± 18.6 mmHg, p = 0.03), and SUVRV/SUVLV, which tended to decrease (mean change -0.20 ± 0.74). Patients with baseline SUVRV/SUVLV value higher than 0.54 had worse prognosis in 48 months observation (log-rank test, p = 0.0007); follow up SUVRV/SUVLV > 1 predicted CEP in the following 24 months, regardless of previously escalated treatment.ConclusionsPAH therapy escalation may influence RV glucose metabolism, what seems to be related with patients’ prognosis. PET/MRI assessment may predict clinical deterioration regardless of previous clinical course, however its clinical significance in PAH requires further studies. Importantly, even mild alterations of RV glucose metabolism predict clinical deterioration in long follow-up.Clinical Trial Registration ClinicalTrials.gov, NCT03688698, 05/01/2016, https://clinicaltrials.gov/ct2/show/study/NCT03688698?term=NCT03688698&draw=2&rank=1
Journal Article
Nonlinear evolution of linear optimal perturbations of strongly stratified shear layers
The Miles–Howard theorem states that a necessary condition for normal-mode instability in parallel, inviscid, steady stratified shear flows is that the minimum gradient Richardson number,
$Ri_{g,min}$
, is less than
$1/4$
somewhere in the flow. However, the non-normality of the Navier–Stokes and buoyancy equations may allow for substantial perturbation energy growth at finite times. We calculate numerically the linear optimal perturbations which maximize the perturbation energy gain for a stably stratified shear layer consisting of a hyperbolic tangent velocity distribution with characteristic velocity
$U_{0}^{\\ast }$
and a uniform stratification with constant buoyancy frequency
$N_{0}^{\\ast }$
. We vary the bulk Richardson number
$Ri_{b}=N_{0}^{\\ast 2}h^{\\ast 2}/U_{0}^{\\ast 2}$
(corresponding to
$Ri_{g,min}$
) between 0.20 and 0.50 and the Reynolds numbers
$\\mathit{Re}=U_{0}^{\\ast }h^{\\ast }/\\unicode[STIX]{x1D708}^{\\ast }$
between 1000 and 8000, with the Prandtl number held fixed at
$\\mathit{Pr}=1$
. We find the transient growth of non-normal perturbations may be sufficient to trigger strongly nonlinear effects and breakdown into small-scale structures, thereby leading to enhanced dissipation and non-trivial modification of the background flow even in flows where
$Ri_{g,min}>1/4$
. We show that the effects of nonlinearity are more significant for flows with higher
$\\mathit{Re}$
, lower
$Ri_{b}$
and higher initial perturbation amplitude
$E_{0}$
. Enhanced kinetic energy dissipation is observed for higher-
$Re$
and lower-
$Ri_{b}$
flows, and the mixing efficiency, quantified here by
$\\unicode[STIX]{x1D700}_{p}/(\\unicode[STIX]{x1D700}_{p}+\\unicode[STIX]{x1D700}_{k})$
where
$\\unicode[STIX]{x1D700}_{p}$
is the dissipation rate of density variance and
$\\unicode[STIX]{x1D700}_{k}$
is the dissipation rate of kinetic energy, is found to be approximately 0.35 for the most strongly nonlinear cases.
Journal Article