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Silicon (Si) released as H4SiO4 by weathering of Si-containing solid phases is partly recycled through vegetation before its land-to-rivers transfer. By accumulating in terrestrial plants to a similar extent as some major macronutrients (0.1–10% Si dry weight), Si becomes largely mobile in the soil-plant system. Litter-fall leads to a substantial reactive biogenic silica pool in soil, which contributes to the release of dissolved Si (DSi) in soil solution. Understanding the biogeochemical cycle of silicon in surface environments and the DSi export from soils into rivers is crucial given that the marine primary bio-productivity depends on the availability of H4SiO4 for phytoplankton that requires Si. Continental fluxes of DSi seem to be deeply influenced by climate (temperature and runoff) as well as soil-vegetation systems. Therefore, continental areas can be characterized by various abilities to transfer DSi from soil-plant systems towards rivers. Here we pay special attention to those processes taking place in soil-plant systems and controlling the Si transfer towards rivers. We aim at identifying relevant geochemical tracers of Si pathways within the soil-plant system to obtain a better understanding of the origin of DSi exported towards rivers. In this review, we compare different soil-plant systems (weathering-unlimited and weathering-limited environments) and the variations of the geochemical tracers (Ge/Si ratios and δ30Si) in DSi outputs. We recommend the use of biogeochemical tracers in combination with Si mass-balances and detailed physico-chemical characterization of soil-plant systems to allow better insight in the sources and fate of Si in these biogeochemical systems.

The integration of magnetic resonance imaging (MRI) for guidance in external beam radiotherapy has faced significant research and development efforts in recent years. The current availability of linear accelerators with an embedded MRI unit, providing volumetric imaging at excellent soft tissue contrast, is expected to provide novel possibilities in the implementation of image-guided adaptive radiotherapy (IGART) protocols. This study reviews open medical physics issues in MR-guided radiotherapy (MRgRT) implementation, with a focus on current approaches and on the potential for innovation in IGART. Daily imaging in MRgRT provides the ability to visualize the static anatomy, to capture internal tumor motion and to extract quantitative image features for treatment verification and monitoring. Those capabilities enable the use of treatment adaptation, with potential benefits in terms of personalized medicine. The use of online MRI requires dedicated efforts to perform accurate dose measurements and calculations, due to the presence of magnetic fields. Likewise, MRgRT requires dedicated quality assurance (QA) protocols for safe clinical implementation. Reaction to anatomical changes in MRgRT, as visualized on daily images, demands for treatment adaptation concepts, with stringent requirements in terms of fast and accurate validation before the treatment fraction can be delivered. This entails specific challenges in terms of treatment workflow optimization, QA, and verification of the expected delivered dose while the patient is in treatment position. Those challenges require specialized medical physics developments towards the aim of fully exploiting MRI capabilities. Conversely, the use of MRgRT allows for higher confidence in tumor targeting and organs-at-risk (OAR) sparing. The systematic use of MRgRT brings the possibility of leveraging IGART methods for the optimization of tumor targeting and quantitative treatment verification. Although several challenges exist, the intrinsic benefits of MRgRT will provide a deeper understanding of dose delivery effects on an individual basis, with the potential for further treatment personalization.

The role of eroding landscapes in organic carbon stabilization operating as C sinks or sources has been frequently discussed, but the underlying mechanisms are not fully understood. Our analysis aims to clarify the effects of soil redistribution on physical and biogeochemical soil organic carbon (SOC) stabilization mechanisms along a hillslope transect. The observed mineralogical differences seem partly responsible for the effectiveness of geochemical and physical SOC stabilization mechanisms as the mineral environment along the transect is highly variable and dynamic. The abundance of primary and secondary minerals and the weathering status of the investigated soils differ drastically along this transect. Extractable iron and aluminum components are generally abundant in aggregates, but show no strong correlation to SOC, indicating their importance for aggregate stability but not for SOC retention. We further show that pyrophosphate extractable soil components, especially manganese, play a role in stabilizing SOC within non-aggregated mineral fractions. The abundance of microbial residues and measured 14C ages for aggregated and non-aggregated SOC fractions demonstrate the importance of the combined effect of geochemical and physical protection to stabilize SOC after burial at the depositional site. Mineral alteration and the breakdown of aggregates limit the protection of C by minerals and within aggregates temporally. The 14C ages of buried soil indicate that C in aggregated fractions seems to be preserved more efficiently while C in non-aggregated fractions is released, allowing a re-sequestration of younger C with this fraction. Old 14C ages and at the same time high contents of microbial residues in aggregates suggest either that microorganisms feed on old carbon to build up microbial biomass or that these environments consisting of considerable amounts of old C are proper habitats for microorganisms and preserve their residues. Due to continuous soil weathering and, hence, weakening of protection mechanisms, a potential C sink through soil burial is finally temporally limited.

The Dutch Ministry of Health has formulated ambitious goals concerning the use of telehealth, leading to subsequent changes compared with the current health care situation, in which 93% of care is delivered face-to-face. Since most care is delivered to older people, the prospect of telehealth raises the question of whether this population is ready for this new way of receiving care. To study this, we created a theoretical framework consisting of 6 factors associated with older people's intention to use technology. The objective of this study was to understand community-dwelling older people's readiness for receiving telehealth by studying their intention to use videoconferencing and capacities for using digital technology in daily life as indicators. A mixed-method triangulation design was used. First, a cross-sectional survey study was performed to investigate older people's intention to use videoconferencing, by testing our theoretical framework with a multilevel path analysis (phase 1). Second, for deeper understanding of older people's actual use of digital technology, qualitative observations of older people executing technological tasks (eg, on a computer, cell phone) were conducted at their homes (phase 2). In phase 1, a total of 256 people aged 65 years or older participated in the survey study (50.0% male; median age, 70 years; Q1-Q3: 67-76). Using a significance level of .05, we found seven significant associations regarding older people's perception of videoconferencing. Older people's (1) intention to use videoconferencing was predicted by their performance expectancy (odds ratio [OR] 1.26, 95% CI 1.13-1.39), effort expectancy (OR 1.23, 95% CI 1.07-1.39), and perceived privacy and security (OR 1.30, 95% CI 1.17-1.43); (2) their performance expectancy was predicted by their effort expectancy (OR 1.38, 95% CI 1.24-1.52); and (3) their effort expectancy was predicted by their self-efficacy (OR 1.55, 95% CI 1.42-1.68). In phase 2, a total of 6 men and 9 women aged between 65 and 87 years participated in the qualitative observation study. Of the primary themes, 5 themes were identified that could provide greater understanding of older people's capacities and incapacities in using digital technology: (1) \"self-efficacy and digital literacy,\" (2) \"obstacles to using technology,\" (3) \"prior experience and frequency of use,\" (4) \"sources of support and facilitating conditions,\" and (5) \"performance expectancy.\" These 5 themes recurred in all 15 observations. Performance expectancy, effort expectancy, and perceived privacy and security are direct predictors of older people's intention to use videoconferencing. Self-efficacy appeared to play a role in both older people's intention to use, as well as their actual use of technology. The path analysis revealed that self-efficacy was significantly associated with older people's effort expectancy. Furthermore, self-efficacy and digital literacy appeared to play a major role in older people's capacities to make use of digital technology.

Medical care for admitted patients in hospitals is increasingly reallocated to physician assistants (PAs). There is limited evidence about the consequences for the quality and safety of care. This study aimed to determine the effects of substitution of inpatient care from medical doctors (MDs) to PAs on patients' length of stay (LOS), quality and safety of care, and patient experiences with the provided care. In a multicenter matched-controlled study, the traditional model in which only MDs are employed for inpatient care (MD model) was compared with a mixed model in which besides MDs also PAs are employed (PA/MD model). Thirty-four wards were recruited across the Netherlands. Patients were followed from admission till one month after discharge. Primary outcome measure was patients' LOS. Secondary outcomes concerned eleven indicators for quality and safety of inpatient care and patients' experiences with the provided care. Data on 2,307 patients from 34 hospital wards was available. The involvement of PAs was not significantly associated with LOS (β 1.20, 95%CI 0.99-1.40, p = .062). None of the indicators for quality and safety of care were different between study arms. However, the involvement of PAs was associated with better experiences of patients (β 0.49, 95% CI 0.22-0.76, p = .001). This study did not find differences regarding LOS and quality of care between wards on which PAs, in collaboration with MDs, provided medical care for the admitted patients, and wards on which only MDs provided medical care. Employing PAs seems to be safe and seems to lead to better patient experiences. ClinicalTrials.gov Identifier: NCT01835444.

Background: Ten years have elapsed since the launch of the International Integrated Reporting Council. Stakeholders increasingly question whether integrated reporting (IR) meets the objectives of decision-usefulness and accountability.Aim: The primary objective of this study was to assess the usefulness of IR by examining the interrelations between the integrated reporting quality (IRQ), sustainability performance and financial performance of listed companies in South Africa.Setting: The study is conducted in the country where integrated reporting is most established. The links between the IRQ of the Top 100 companies listed on the Johannesburg Stock Exchange and their environmental, social and corporate governance (ESG) scores and multiple financial indicators are investigated over the period 2013-2018.Methods: The EY Excellence in Integrated Reporting Awards was used as a metric to determine the sample companies' IRQ. These awards were ranked according to four categories, namely 'progress to be made', 'average', 'good' and 'excellent'. Sustainability (ESG scores), as well as financial performance data (accounting-based and market-based variables) were sourced from Bloomberg. The panel data set was analysed by conducting a mixed-model analysis of variance and panel regressions.Results: A high level of IRQ was found to be significantly associated with high levels of ESG performance, as well as high earnings per share and high leverage.Conclusion: It appears that IR strengthens managerial efficiency and legitimacy in the eyes of debt capital providers in South Africa, while equity capital providers do not provide a clear signal of approval.

In the radiofrequency (RF) range, the electrical properties of tissues (EPs: conductivity and permittivity) are modulated by the ionic and water content, which change for pathological conditions. Information on tissues EPs can be used e.g. in oncology as a biomarker. The inability of MR-Electrical Properties Tomography techniques (MR-EPT) to accurately reconstruct tissue EPs by relating MR measurements of the transmit RF field to the EPs limits their clinical applicability. Instead of employing electromagnetic models posing strict requirements on the measured MRI quantities, we propose a data driven approach where the electrical properties reconstruction problem can be casted as a supervised deep learning task (DL-EPT). DL-EPT reconstructions for simulations and MR measurements at 3 Tesla on phantoms and human brains using a conditional generative adversarial network demonstrate high quality EPs reconstructions and greatly improved precision compared to conventional MR-EPT. The supervised learning approach leverages the strength of electromagnetic simulations, allowing circumvention of inaccessible MR electromagnetic quantities. Since DL-EPT is more noise-robust than MR-EPT, the requirements for MR acquisitions can be relaxed. This could be a major step forward to turn electrical properties tomography into a reliable biomarker where pathological conditions can be revealed and characterized by abnormalities in tissue electrical properties.

The quantification of silicon (Si) uptake by tree species is a mandatory step to study the role of forest vegetations in the global cycle of Si. Forest tree species can impact the hydrological output of dissolved Si (DSi) through root induced weathering of silicates but also through Si uptake and restitution via litterfall. Here, monospecific stands of Douglas fir, Norway spruce, Black pine, European beech and oak established in identical soil and climate conditions were used to quantify Si uptake, immobilization and restitution. We measured the Si contents in various compartments of the soil—tree system and we further studied the impact of the recycling of Si by forest trees on the DSi pool. Si is mainly accumulated in leaves and needles in comparison with other tree compartments (branches, stembark and stemwood). The immobilization of Si in tree biomass represents less than 15% of the total Si uptake. Annual Si uptake by oak and European beech stands is 18.5 and 23.3 kg ha⁻¹ year⁻¹, respectively. Black pine has a very low annual Si uptake (2.3 kg ha⁻¹ year⁻¹) in comparison with Douglas fir (30.6 kg ha⁻¹ year⁻¹) and Norway spruce (43.5 kg ha⁻¹ year⁻¹). The recycling of Si by forest trees plays a major role in the continental Si cycle since tree species greatly influence the uptake and restitution of Si. Moreover, we remark that the annual tree uptake is negatively correlated with the annual DSi output at 60 cm depth. The land—ocean fluxes of DSi are certainly influenced by geochemical processes such as weathering of primary minerals and formation of secondary minerals but also by biological processes such as root uptake.