7 results
The usability of daytime and night-time heart rate dynamics as digital biomarkers of depression severity
- S. Siddi, R. Bailon, I. Giné-Vázquez, F. Matcham, F. Lamers, S. Kontaxis, E. Laporta, E. Garcia, F. Lombardini, P. Annas, M. Hotopf, B. W. J. H. Penninx, A. Ivan, K. M. White, S. Difrancesco, P. Locatelli, J. Aguiló, M. T. Peñarrubia-Maria, V. A. Narayan, A. Folarin, D. Leightley, N. Cummins, S. Vairavan, Y. Ranjan, A. Rintala, G. de Girolamo, S. K. Simblett, T. Wykes, PAB members, I. Myin-Germeys, R. Dobson, J. M. Haro
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- Journal:
- Psychological Medicine / Volume 53 / Issue 8 / June 2023
- Published online by Cambridge University Press:
- 15 May 2023, pp. 3249-3260
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Background
Alterations in heart rate (HR) may provide new information about physiological signatures of depression severity. This 2-year study in individuals with a history of recurrent major depressive disorder (MDD) explored the intra-individual variations in HR parameters and their relationship with depression severity.
MethodsData from 510 participants (Number of observations of the HR parameters = 6666) were collected from three centres in the Netherlands, Spain, and the UK, as a part of the remote assessment of disease and relapse-MDD study. We analysed the relationship between depression severity, assessed every 2 weeks with the Patient Health Questionnaire-8, with HR parameters in the week before the assessment, such as HR features during all day, resting periods during the day and at night, and activity periods during the day evaluated with a wrist-worn Fitbit device. Linear mixed models were used with random intercepts for participants and countries. Covariates included in the models were age, sex, BMI, smoking and alcohol consumption, antidepressant use and co-morbidities with other medical health conditions.
ResultsDecreases in HR variation during resting periods during the day were related with an increased severity of depression both in univariate and multivariate analyses. Mean HR during resting at night was higher in participants with more severe depressive symptoms.
ConclusionsOur findings demonstrate that alterations in resting HR during all day and night are associated with depression severity. These findings may provide an early warning of worsening depression symptoms which could allow clinicians to take responsive treatment measures promptly.
Remote Assessment of Disease and Relapse in Major Depressive Disorder (RADAR-MDD): Recruitment, retention, and data availability in a longitudinal remote measurement study
- F. Matcham, D. Leightley, S. Siddi, F. Lamers, K. White, P. Annas, G. De Girolamo, S. Difrancesco, J.M. Haro, M. Horsfall, A. Ivan, G. Lavelle, Q. Li, F. Lombardini, D. Mohr, V. Narayan, C. Oetzmann, B. Penninx, S. Simblett, S. Bruce, R. Nica, T. Wykes, J. Brasen, I. Myin-Germeys, A. Rintala, P. Conde, R. Dobson, A. Folarin, C. Stewart, Y. Ranjan, Z. Rashid, N. Cummins, N. Manyakov, S. Vairavan, M. Hotopf
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- Journal:
- European Psychiatry / Volume 65 / Issue S1 / June 2022
- Published online by Cambridge University Press:
- 01 September 2022, p. S112
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Introduction
Major Depressive Disorder (MDD) is prevalent, often chronic, and requires ongoing monitoring of symptoms to track response to treatment and identify early indicators of relapse. Remote Measurement Technologies (RMT) provide an exciting opportunity to transform the measurement and management of MDD, via data collected from inbuilt smartphone sensors and wearable devices alongside app-based questionnaires and tasks.
ObjectivesTo describe the amount of data collected during a multimodal longitudinal RMT study, in an MDD population.
MethodsRADAR-MDD is a multi-centre, prospective observational cohort study. People with a history of MDD were provided with a wrist-worn wearable, and several apps designed to: a) collect data from smartphone sensors; and b) deliver questionnaires, speech tasks and cognitive assessments and followed-up for a maximum of 2 years.
ResultsA total of 623 individuals with a history of MDD were enrolled in the study with 80% completion rates for primary outcome assessments across all timepoints. 79.8% of people participated for the maximum amount of time available and 20.2% withdrew prematurely. Data availability across all RMT data types varied depending on the source of data and the participant-burden for each data type. We found no evidence of an association between the severity of depression symptoms at baseline and the availability of data. 110 participants had > 50% data available across all data types, and thus able to contribute to multiparametric analyses.
ConclusionsRADAR-MDD is the largest multimodal RMT study in the field of mental health. Here, we have shown that collecting RMT data from a clinical population is feasible.
DisclosureNo significant relationships.
Turbulent mixing driven by spherical implosions. Part 1. Flow description and mixing-layer growth
- M. Lombardini, D. I. Pullin, D. I. Meiron
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- Journal of Fluid Mechanics / Volume 748 / 10 June 2014
- Published online by Cambridge University Press:
- 28 April 2014, pp. 85-112
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We present large-eddy simulations (LES) of turbulent mixing at a perturbed, spherical interface separating two fluids of differing densities and subsequently impacted by a spherically imploding shock wave. This paper focuses on the differences between two fundamental configurations, keeping fixed the initial shock Mach number ${\approx }1.2$, the density ratio (precisely $|A_0|\approx 0.67$) and the perturbation shape (dominant spherical wavenumber $\ell _0=40$ and amplitude-to-initial radius of $3\, \%$): the incident shock travels from the lighter fluid to the heavy fluid or, inversely, from the heavy to the light fluid. After describing the computational problem we present results on the radially symmetric flow, the mean flow, and the growth of the mixing layer. Turbulent statistics are developed in Part 2 (Lombardini, M., Pullin, D. I. & Meiron, D. I. J. Fluid Mech., vol. 748, 2014, pp. 113–142). A wave-diagram analysis of the radially symmetric flow highlights that the light–heavy mixing layer is processed by consecutive reshocks, and not by reverberating rarefaction waves as is usually observed in planar geometry. Less surprisingly, reshocks process the heavy–light mixing layer as in the planar case. In both configurations, the incident imploding shock and the reshocks induce Richtmyer–Meshkov (RM) instabilities at the density layer. However, we observe differences in the mixing-layer growth because the RM instability occurrences, Rayleigh–Taylor (RT) unstable scenarios (due to the radially accelerated motion of the layer) and phase inversion events are different. A small-amplitude stability analysis along the lines of Bell (Los Alamos Scientific Laboratory Report, LA-1321, 1951) and Plesset (J. Appl. Phys., vol. 25, 1954, pp. 96–98) helps quantify the effects of the mean flow on the mixing-layer growth by decoupling the effects of RT/RM instabilities from Bell–Plesset effects associated with geometric convergence and compressibility for arbitrary convergence ratios. The analysis indicates that baroclinic instabilities are the dominant effect, considering the low convergence ratio (${\approx } 2$) and rather high ($\ell >10$) mode numbers considered.
Turbulent mixing driven by spherical implosions. Part 2. Turbulence statistics
- M. Lombardini, D. I. Pullin, D. I. Meiron
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- Journal:
- Journal of Fluid Mechanics / Volume 748 / 10 June 2014
- Published online by Cambridge University Press:
- 28 April 2014, pp. 113-142
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We present large-eddy simulations (LES) of turbulent mixing at a perturbed, spherical interface separating two fluids of differing densities and subsequently impacted by a spherically imploding shock wave. This paper focuses on the differences between two fundamental configurations, keeping fixed the initial shock Mach number $\approx $1.2, the density ratio (precisely $|A_0|\approx 0.67$) and the perturbation shape (dominant spherical wavenumber $\ell _0=40$ and amplitude-to-initial radius of 3 %): the incident shock travels from the lighter fluid to the heavy one, or inversely, from the heavy to the light fluid. In Part 1 (Lombardini, M., Pullin, D. I. & Meiron, D. I., J. Fluid Mech., vol. 748, 2014, pp. 85–112), we described the computational problem and presented results on the radially symmetric flow, the mean flow, and the growth of the mixing layer. In particular, it was shown that both configurations reach similar convergence ratios $\approx $2. Here, turbulent mixing is studied through various turbulence statistics. The mixing activity is first measured through two mixing parameters, the mixing fraction parameter $\varTheta $ and the effective Atwood ratio $A_e$, which reach similar late time values in both light–heavy and heavy–light configurations. The Taylor-scale Reynolds numbers attained at late times are estimated at approximately 2000 in the light–heavy case and 1000 in the heavy–light case. An analysis of the density self-correlation $b$, a fundamental quantity in the study of variable-density turbulence, shows asymmetries in the mixing layer and non-Boussinesq effects generally observed in high-Reynolds-number Rayleigh–Taylor (RT) turbulence. These traits are more pronounced in the light–heavy mixing layer, as a result of its flow history, in particular because of RT-unstable phases (see Part 1). Another measure distinguishing light–heavy from heavy–light mixing is the velocity-to-scalar Taylor microscales ratio. In particular, at late times, larger values of this ratio are reported in the heavy–light case. The late-time mixing displays the traits some of the traits of the decaying turbulence observed in planar Richtmyer–Meshkov (RM) flows. Only partial isotropization of the flow (in the sense of turbulent kinetic energy (TKE) and dissipation) is observed at late times, the Reynolds normal stresses (and, thus, the directional Taylor microscales) being anisotropic while the directional Kolmogorov microscales approach isotropy. A spectral analysis is developed for the general study of statistically isotropic turbulent fields on a spherical surface, and applied to the present flow. The resulting angular power spectra show the development of an inertial subrange approaching a Kolmogorov-like $-5/3$ power law at high wavenumbers, similarly to the scaling obtained in planar geometry. It confirms the findings of Thomas & Kares (Phys. Rev. Lett., vol. 109, 2012, 075004) at higher convergence ratios and indicates that the turbulent scales do not seem to feel the effect of the spherical mixing-layer curvature.
Transition to turbulence in shock-driven mixing: a Mach number study
- M. Lombardini, D. I. Pullin, D. I. Meiron
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- Journal of Fluid Mechanics / Volume 690 / 10 January 2012
- Published online by Cambridge University Press:
- 21 November 2011, pp. 203-226
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Large-eddy simulations of single-shock-driven mixing suggest that, for sufficiently high incident Mach numbers, a two-gas mixing layer ultimately evolves to a late-time, fully developed turbulent flow, with Kolmogorov-like inertial subrange following a power law. After estimating the kinetic energy injected into the diffuse density layer during the initial shock–interface interaction, we propose a semi-empirical characterization of fully developed turbulence in such flows, based on scale separation, as a function of the initial parameter space, as , which corresponds to late-time Taylor-scale Reynolds numbers . In this expression, represents the post-shock perturbation amplitude, the change in interface velocity induced by the shock refraction, the characteristic kinematic viscosity of the mixture, the inner diffuse thickness of the initial density profile, the post-shock Atwood ratio, and for the gas combination and post-shock perturbation amplitude considered. The initially perturbed interface separating air and SF6 (pre-shock Atwood ratio ) was impacted in a heavy–light configuration by a shock wave of Mach number , 1.25, 1.56, 3.0 or 5.0, for which is fixed at about 25 % of the dominant wavelength of an initial, Gaussian perturbation spectrum. Only partial isotropization of the flow (in the sense of turbulent kinetic energy and dissipation) is observed during the late-time evolution of the mixing zone. For all Mach numbers considered, the late-time flow resembles homogeneous decaying turbulence of Batchelor type, with a turbulent kinetic energy decay exponent and large-scale () energy spectrum , and a molecular mixing fraction parameter, . An appropriate time scale characterizing the Taylor-scale Reynolds number decay, as well as the evolution of mixing parameters such as and the effective Atwood ratio , seem to indicate the existence of low- and high-Mach-number regimes.
Atwood ratio dependence of Richtmyer–Meshkov flows under reshock conditions using large-eddy simulations
- M. LOMBARDINI, D. J. HILL, D. I. PULLIN, D. I. MEIRON
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- Journal of Fluid Mechanics / Volume 670 / 10 March 2011
- Published online by Cambridge University Press:
- 01 February 2011, pp. 439-480
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We study the shock-driven turbulent mixing that occurs when a perturbed planar density interface is impacted by a planar shock wave of moderate strength and subsequently reshocked. The present work is a systematic study of the influence of the relative molecular weights of the gases in the form of the initial Atwood ratio A. We investigate the cases A = ± 0.21, ±0.67 and ±0.87 that correspond to the realistic gas combinations air–CO2, air–SF6 and H2–air. A canonical, three-dimensional numerical experiment, using the large-eddy simulation technique with an explicit subgrid model, reproduces the interaction within a shock tube with an endwall where the incident shock Mach number is ~1.5 and the initial interface perturbation has a fixed dominant wavelength and a fixed amplitude-to-wavelength ratio ~0.1. For positive Atwood configurations, the reshock is followed by secondary waves in the form of alternate expansion and compression waves travelling between the endwall and the mixing zone. These reverberations are shown to intensify turbulent kinetic energy and dissipation across the mixing zone. In contrast, negative Atwood number configurations produce multiple secondary reshocks following the primary reshock, and their effect on the mixing region is less pronounced. As the magnitude of A is increased, the mixing zone tends to evolve less symmetrically. The mixing zone growth rate following the primary reshock approaches a linear evolution prior to the secondary wave interactions. When considering the full range of examined Atwood numbers, measurements of this growth rate do not agree well with predictions of existing analytic reshock models such as the model by Mikaelian (Physica D, vol. 36, 1989, p. 343). Accordingly, we propose an empirical formula and also a semi-analytical, impulsive model based on a diffuse-interface approach to describe the A-dependence of the post-reshock growth rate.
Salinity tolerance in Phillyrea species
- R. GUCCI, G. ARONNE, L. LOMBARDINI, M. TATTINI
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- The New Phytologist / Volume 135 / Issue 2 / February 1997
- Published online by Cambridge University Press:
- 01 February 1997, pp. 227-234
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- February 1997
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The genus Phillyrea includes woody shrub species of Mediterranean maquis which can be found occasionally in saline soils or areas exposed to salt aerosols. To test salinity tolerance in Phillyrea latifolia L., plants were grown in 1-l containers and exposed to different levels of salinity in a glasshouse over two growing seasons. Plants survived exposure to NaCl concentrations of up to 500 mM NaCl for 4 months. Analysis of the growth response to increasing salinity showed that shoot elongation was inhibited by 50% at 123 and 135 mM external NaCl after 31 and 123 d of salt treatment, respectively. Growth parameters were completely inhibited by treatment with 300 mM external NaCl for 64 d. High salt tolerance in Phillyrea plants was the result of both exclusion and secretion mechanisms. Secretion of ions occurred via salt glands present mainly on the abaxial surface of the leaf. Salt glands occurred alone or in pairs and were typically formed by a highly vacuolated collecting cell, a stalk cell and a group of 10–16 secretory cells. The mean diameter of the glands was 54 μm and the average density was 6·1 mM−2 (abaxial side). Peaks of Cl, K, Ca, Na, Si, Mg, Fe and Cu were detected in salt crystals near glands by X-ray microprobe analysis. This is the first report of salt glands in the Oleaceae family and of their role in salinity tolerance in Phillyrea species.