Numerical bifurcation analysis of pattern formation in a cell based auxin transport model

Transport models of growth hormones can be used to reproduce the hormone accumulations that occur in plant organs. Mostly, these accumulation patterns are calculated using time step methods, even though only the resulting steady state patterns of the model are of interest. We examine the steady state solutions of the hormone transport model of Smith et al (2006) for a one-dimensional row of plant cells. We search for the steady state solutions as a function of three of the model parameters by using numerical continuation methods and bifurcation analysis. These methods are more adequate for solving steady state problems than time step methods. We discuss a trivial solution where the concentrations of hormones are equal in all cells and examine its stability region. We identify two generic bifurcation scenarios through which the trivial solution loses its stability. The trivial solution becomes either a steady state pattern with regular spaced peaks or a pattern where the concentration is periodic in time.Comment: submitte

Vocational Rehabilitation for Patients with Chronic Musculoskeletal Pain With or Without a Work Module:An Economic Evaluation

Purpose Vocational rehabilitation (VR) is a widely used intervention aimed to optimize work participation for patients on sick leave due to chronic musculoskeletal pain (CMP). Economic evaluations of care as usual VR are scarce, and may provide relevant information to guide clinical, reimbursement and policy decisions. The aim of this study was to evaluate the short-term cost-effectiveness and return on investment (ROI) of VR for patients on sick leave due to CMP with an additional work module (VR+) compared to VR without work module, from a societal and employers' perspective. Methods A retrospective longitudinal cohort study within a Dutch care as usual context was applied. Participants with CMP and decreased work participation originating from seven Dutch rehabilitation centers were included in this study. Participants underwent VR or VR+. Main data sources at baseline and discharge: Quality-adjusted life year (QALY) based on EQ-5D, intervention costs, self-reported productivity and health care utilization. Main analyses cost-effectiveness, including incremental cost-effectiveness ratio (ICER) and a cost-effectiveness acceptability curve (CEAC); and ROI analyses with use of the human capital method. Results N = 324 participants were analyzed. The results show that VR+ was cost-effective compared to VR: mean cost savings of €820 per 0.012 QALY gained. CEAC suggests probability of VR+ being cost-effective is > 0.91 for thresholds of €20.000 and higher. The mean ROI of VR+ for employers was 38%. Conclusion It was concluded that at discharge, VR+ was cost-effective compared to VR. ROI was positive for employers

Usefulness and feasibility of comprehensive and less comprehensive vocational rehabilitation for patients with chronic musculoskeletal pain:perspectives from patients, professionals, and managers

Purpose: To explore the usefulness and feasibility of a comprehensive vocational rehabilitation (C-VR) program and less comprehensive (LC-VR) program for workers on sick leave due to chronic musculoskeletal pain, from the perspective of patients, professionals, and managers.Materials and methods: Semi-structured interviews were held with patients, professionals, and managers. Using topic lists, participants were questioned about barriers to and facilitators of the usefulness and feasibility of C-VR and LC-VR. Thirty interviews were conducted with thirteen patients (n = 6 C-VR, n = 7 LC-VR), eight professionals, and nine managers. All interviews were transcribed verbatim. Data were analyzed by systematic text condensation using inductive thematic analysis.Results: Three themes emerged for usefulness ("patient factors," "content," "dosage") and six themes emerged for feasibility ("satisfaction," "intention to continue use," "perceived appropriateness," "positive/negative effects on target participants," "factors affecting implementation ease or difficulty," "adaptations"). The patients reported that both programs were feasible and generally useful. The professionals preferred working with the C-VR, although they disliked the fixed and uniform character of the program. They also mentioned that this program is too extensive for some patients, and that the latter would probably benefit from the LC-VR program. Despite their positive intentions, the managers stated that due to the Dutch healthcare system, implementation of the LC-VR program would be financially unfeasible.Conclusions: The main conclusion of this study is that it is not useful to have one VR program for all patients with CMP and reduced work participation, and that flexible and tailored-based VR are warranted.Implications for rehabilitationBoth comprehensive and less comprehensive vocational rehabilitation are deemed useful for patients with chronic musculoskeletal pain and reduced work participation. Particular patient factors, for instance information uptake, discipline, willingness to change, duration of complaints, movement anxiety, obstructing thoughts, and willingness to return to work might guide the right program for the right patient.Both comprehensive and less comprehensive vocational rehabilitation are deemed feasible in practice. However, factors such as center logistic (schemes, rooms, professionals available) and country-specific healthcare insurance and sickness compensation systems should foster the implementation of less comprehensive programs

Physiological and biochemical analyses shed light on the response of sargassum vulgare to ocean acidification at different time scales

Studies regarding macroalgal responses to ocean acidification (OA) are mostly limited to short-term experiments in controlled conditions, which hamper the possibility to scale up the observations to long-term effects in the natural environment. To gain a broader perspective, we utilized volcanic CO2 vents as a “natural laboratory” to study OA effects on Sargassum vulgare at different time scales. We measured photosynthetic rates, oxidative stress levels, antioxidant contents, antioxidant enzyme activities, and activities of oxidative metabolic enzymes in S. vulgare growing at a natural acidified site (pH 6.7) compared to samples from a site with current pH (pH 8.2), used as a control one. These variables were also tested in plants transplanted from the control to the acidified site and vice-versa. After short-term exposure, photosynthetic rates and energy metabolism were increased in S. vulgare together with oxidative damage. However, in natural populations under long-term conditions photosynthetic rates were similar, the activity of oxidative metabolic enzymes was maintained, and no sign of oxidative damages was observed. The differences in the response of the macroalga indicate that the natural population at the acidified site is adapted to live at the lowered pH. The results suggest that this macroalga can adopt biochemical and physiological strategies to grow in future acidified oceans

Drought induces distinct growth response, protection, and recovery mechanisms in the maize leaf growth zone

Drought is the most important crop yield-limiting factor, and detailed knowledge of its impact on plant growth regulation is crucial. The maize (Zea mays) leaf growth zone offers unique possibilities for studying the spatiotemporal regulation of developmental processes by transcriptional analyses and methods that require more material, such as metabolite and enzyme activity measurements. By means of a kinematic analysis, we show that drought inhibits maize leaf growth by inhibiting cell division in the meristem and cell expansion in the elongation zone. Through a microarray study, we observed the down- regulation of 32 of the 54 cell cycle genes, providing a basis for the inhibited cell division. We also found evidence for an up- regulation of the photosynthetic machinery and the antioxidant and redox systems. This was confirmed by increased chlorophyll content in mature cells and increased activity of antioxidant enzymes and metabolite levels across the growth zone, respectively. We demonstrate the functional significance of the identified transcriptional reprogramming by showing that increasing the antioxidant capacity in the proliferation zone, by overexpression of the Arabidopsis (Arabidopsis thaliana) iron-superoxide dismutase gene, increases leaf growth rate by stimulating cell division. We also show that the increased photosynthetic capacity leads to enhanced photosynthesis upon rewatering, facilitating the often-observed growth compensation.Fil: Avramova, Viktoriya. Universiteit Antwerp; BélgicaFil: Abdelgawad, Hamada. University of Beni-Suef; EgiptoFil: Zhang, Zhengfeng. Central China Normal University; ChinaFil: Fotschki, Bartosz. Institute of Animal Reproduction and Food Research; PoloniaFil: Casadevall, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Vergauwen, Lucia. Universiteit Antwerp; BélgicaFil: Knapen, Dries. Universiteit Antwerp; BélgicaFil: Taleisnik, Edith. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Guisez, Yves. Universiteit Antwerp; BélgicaFil: Asard, Han. Universiteit Antwerp; BélgicaFil: Beemster, Gerrit T. S.. Universiteit Antwerp; Bélgic

The interpretation of change score of the pain disability index after vocational rehabilitation is baseline dependent

Background: The Pain Disability Index (PDI) is a widely-used instrument to measure pain-related disability. The aim of this study was to assess the responsiveness and interpretation of change score of the PDI in patients with chronic musculoskeletal pain (CMP) at discharge of vocational rehabilitation. Methods: Retrospective data of patients with CMP who attended vocational rehabilitation between 2014 and 2017 was used. The anchor-based method was used to assess the responsiveness of the total sample and of PDI baseline quartile groups. A receiver operating characteristic curve was performed, including Area Under the Curve (AUC) and Minimal Important Change (MIC). Results: The PDI showed responsive to detect clinically relevant changes in pain-related disability at discharge of vocational rehabilitation (AUC 0.79). A PDI change score of 13 points (MIC 12.5) can be considered as a real change in pain-related disability for the total study sample, and a PDI change score of 7-20 points can be considered as a real change in pain-related disability for PDI lowest and highest baseline quartile scores. Conclusion: The PDI is responsive in patients with CMP at discharge of vocational rehabilitation. The interpretation of change score depends on PDI baseline score. Patients with a PDI baseline score of ≤27 should decrease minimal 7 points, patients with a baseline score between 28 and 42 should decrease minimal 15 points, and patients with a baseline score ≥ 43 should decrease minimal 20 points

Test-Retest Reliability, Agreement and Responsiveness of Productivity Loss (iPCQ-VR) and Healthcare Utilization (TiCP-VR) Questionnaires for Sick Workers with Chronic Musculoskeletal Pain

PurposeThe purpose of this study was to assess test-retest reliability, agreement, and responsiveness of questionnaires on productivity loss (iPCQ-VR) and healthcare utilization (TiCP-VR) for sick-listed workers with chronic musculoskeletal pain who were referred to vocational rehabilitation. Methods Test-retest reliability and agreement was assessed with a 2-week interval. Responsiveness was assessed at discharge after a 15-week vocational rehabilitation (VR) program. Data was obtained from six Dutch VR centers. Test-retest reliability was determined with intraclass correlation coefficient (ICC) and Cohen's kappa. Agreement was determined by Standard Error of Measurement (SEM), smallest detectable changes (on group and individual level), and percentage observed, positive and negative agreement. Responsiveness was determined with area under the curve (AUC) obtained from receiver operation characteristic (ROC). Results A sample of 52 participants on test-retest reliability and agreement, and a sample of 223 on responsiveness were included in the analysis. Productivity loss (iPCQ-VR): ICCs ranged from 0.52 to 0.90, kappa ranged from 0.42 to 0.96, and AUC ranged from 0.55 to 0.86. Healthcare utilization (TiCP-VR): ICC was 0.81, and kappa values of the single healthcare utilization items ranged from 0.11 to 1.00. Conclusions The iPCQ-VR showed good measurement properties on working status, number of hours working per week and long-term sick leave, and low measurement properties on short-term sick leave and presenteeism. The TiCP-VR showed adequate reliability on all healthcare utilization items together and medication use, but showed low measurement properties on the single healthcare utilization items