Resilience of pore-water chemistry and calcification in photosynthetic zones of calcifying sediments

Photosynthetically driven calcification was investigated in diatom‐dominated carbonate sediments from Bait Reef, Australia. Laboratory measurements conducted over complete diel cycles, using O2, pH, CO32‐, and Ca2+ microsensors, confirmed that photosynthesis and respiration drive calcification and calcium release via their respective effects on the local pH. However, the dark situation does not simply mirror the light situation. Profiles showed that calcification and calcium release are not necessarily tightly coupled to the light cycle and that mass transfer phenomena need to be considered in diel chemical dynamics. The magnitude and timing of pH and CO2{ 3 concentration changes did not simply follow the light cycle. The pH in the upper 3 mm of the sediment changed more rapidly upon illumination than upon darkening. Consequently, photosynthetically induced calcification began shortly (within 1 h) after illumination, but the pH remained elevated and calcification continued for ~7 h after darkening. Thus, calcification in marine phototrophic sediments is not limited to light periods, but may continue for extended periods after darkening. This decoupling of light, photosynthesis, and calcification has profound consequences for estimates of daily calcification rates, which have previously been made from measurements assuming close to steady states and 12 : 12 h light : dark calcification and decalcification. In Bait Reef sediments, such an assumption underestimates daily calcification rates by two‐ to threefold

Optical modeling of ocean waters: Is the case 1 - case 2 classification still useful?

…two extreme cases can be identified and separated. Case 1 is that of a concentration of phytoplankton high compared to other particles…. In contrast, the inorganic particles are dominant in case 2.… In both cases dissolved yellow substance is present in variable amounts.… An ideal case 1 would be a pure culture of phytoplankton and an ideal case 2 a suspension of nonliving material with a zero concentration of pigments. Morel and Prieur emphasized that these ideal cases are not encountered in nature, and they suggested the use of high or low values of the ratio of pigment concentration to scattering coefficient as a basis for discriminating between Case 1 and Case 2 waters. Although no specific values of this ratio were proposed to serve as criteria for classification, their example data suggested that the ratio of chlorophyll a concentration (in mg m-3) to the scattering coefficient at 550 nm (in m-1) in Case 1 waters is greater than 1 and in Case 2 waters is less than 1. Importantly, however, Morel and Prieur also showed data classified as “intermediate waters” with the ratio between about 1 and 2.2. Although the original definition from 1977 did not imply a binary classification, the practice of most investigators in the following years clearly evolved toward a bipartite analysis

Metabolic microenvironmental control by photosynthetic biofilms under changing macroenvironmental temperature and pH conditions

Ex situ microelectrode experiments, using cyanobacterial biofilms from karst water creeks, were conducted under various pH, temperature, and constant-alkalinity conditions to investigate the effects of changing environmental parameters on cyanobacterial photosynthesis-induced calcification. Microenvironmental chemical conditions around calcifying sites were controlled by metabolic activity over a wide range of photosynthesis and respiration rates, with little influence from overlying water conditions. Regardless of overlying water pH levels (from 7.8 to 8.9), pH at the biofilm surface was approximately 9.4 in the light and 7.8 in the dark. The same trend was observed at various temperatures (4°C and 17°C). Biological processes control the calcium carbonate saturation state (Ω) in these and similar systems and are able to maintain Ω at approximately constant levels over relatively wide environmental fluctuations. Temperature did, however, have an effect on calcification rate. Calcium flux in this system is limited by its diffusion coefficient, resulting in a higher calcium flux (calcification and dissolution) at higher temperatures, despite the constant, biologically mediated pH. The ability of biological systems to mitigate the effects of environmental perturbation is an important factor that must be considered when attempting to predict the effects of increased atmospheric partial CO2 pressure on processes such as calcification and in interpreting microfossils in the fossil record

Anodic dissolution growth of metal-organic framework HKUST-1 monitored:Via in situ electrochemical atomic force microscopy

In situ electrochemical atomic force microscopy (ec-AFM) is utilised for the first time to probe the initial stages of metal-organic framework (MOF) coating growth via anodic dissolution. Using the example of the Cu MOF HKUST-1, real time surface analysis is obtained that supports and verifies many of the reaction steps in a previously proposed mechanism for this type of coating growth. No evidence is observed however for the presence or formation of Cu2O, which has previously been suggested to be both key for the formation of the coating and a potential explanation for the anomalously high adhesion strength of coatings obtained via this methodology. Supporting in situ electrochemical Raman spectroscopy also fails to detect the presence of any significant amount of Cu2O before or during the coating's growth process

Protocol: inspiratory muscle training for promoting recovery and outcomes in ventilated patients (IMPROVe): a randomised controlled trial

Introduction: Inspiratory muscle weakness is a known consequence of mechanical ventilation and a potential contributor to difficulty in weaning from ventilatory support. Inspiratory muscle training (IMT) reduces the weaning period and increases the likelihood of successful weaning in some patients. However, it is not known how this training affects the residual inspiratory muscle fatigability following successful weaning nor patients' quality of life or functional outcomes. Methods and analysis: This dual centre study includes two concurrent randomised controlled trials of IMT in adult patients who are either currently ventilator-dependent (>7 days) (n=70) or have been recently weaned from mechanical ventilation (>7 days) in the past week (n=70). Subjects will be stable, alert and able to actively participate and provide consent. There will be concealed allocation to either treatment (IMT) or usual physiotherapy (including deep breathing exercises without a resistance device). Primary outcomes are inspiratory muscle fatigue resistance and maximum inspiratory pressures. Secondary outcomes are quality of life (Short Form-36v2, EQ-5D), functional status (Acute Care Index of Function), rate of perceived exertion (Borg Scale), intensive care length of stay (days), post intensive care length of stay (days), rate of reintubation (%) and duration of ventilation (days). Ethics and dissemination: Ethics approval has been obtained from relevant institutions, and results will be published with a view to influencing physiotherapy practice in the management of long-term ventilator-dependent patients to accelerate weaning and optimise rehabilitation outcomes

A highly accurate approach that resolves the pressure spike of elastohydrodynamic lubrication

We propose an accurate numerical method to solve the classical line contact problem of elastohydrodynamic lubrication. The method incorporates a second order accurate discretization and a straightforward automatic local mesh refinement procedure. Using these elements, we remove discretization errors which have produced significant inaccuracies in previously published results, and we completely resolve the pressure spike which is shown to be smooth on a sufficiently small length scale

Cultural Transformations: The Impacts of Hull UK City of Culture 2017. Main Evaluation, Findings and Reflections

This report forms an important output in the overall process of monitoring, evaluation and research to measure the impacts of Hull UK City of Culture 2017. It provides an assessment of the project across all five impact areas, drawing on a range of primary and secondary data. These data were collected to study the extent to which Hull 2017 activities delivered the nine aims and 20 objectives set out for the project by key funders, stakeholders and partner organisations. The research was carried out by the the Culture, Place and Policy Institute (University of Hull), by the Monitoring and Evaluation team at Hull UK City of Culture 2017 Ltd, and by external consultants, supported by the strategic planning and partnership team at Hull City Council

Phase I dose-escalation and pharmacokinetic study of a novel folate analogue AG2034

The novel folate analogue AG2034, which was designed as an inhibitor of GARFT (glycinamide ribonucleotide formyltransferase), was evaluated in this phase I study under the auspices of The Cancer Research Campaign, UK. AG2034 blocks de novo purine synthesis through inhibition of GARFT. A total of 28 patients with histologically proven intractable cancers were enrolled. AG2034 was administered as a short intravenous infusion once every 3 weeks. 8 dose levels ranging from 1–11 mg/m2 were evaluated with patients receiving up to 6 cycles. Dose-limiting toxicities in the form of mucositis, diarrhoea and vomiting were observed at doses of 6 mg/m2 and above. Significant levels of thrombocytopenia, neutropenia and anaemia were also recorded. Other sporadic toxicities included fatigue and myalgia. The MTD with this schedule of AG2034 was 5 mg/m2. Most side effects occurred more frequently with cumulative dosing. In keeping with this, pharmacokinetic analysis revealed evidence of drug accumulation. The AG2034 AUC0–24 increased by a median of 184% (range 20–389%) from cycle 1 to 3 in all 10 patients examined. No objective antitumour responses were observed in the study. © 2001 Cancer Research Campaign http://www.bjcancer.co