Dynamics of oxygen consumption during the formation of the anoxic zone in aquatic environment

Anoxic environments and communities of anaerobic organisms are encountered in aquatic environments and biotechnological reactors. Because of their importance, they are continuously studied. In this study, the dynamics of oxygen removal were observed during experiments reproducing the formation of the anoxic zone. Seven experiments were performed in an aquarium (volume: 60 l) with bottom sediments and water collected from different aquatic environments (river, pond, eutrophic lake, sea). To exclude reaeration, the water was isolated from the air by a layer of liquid paraffin. Below the paraffin layer the water was periodically mixed with a stirrer and sampled for oxygen concentration. Initially, a high rate of oxygen consumption was observed. Later, at low oxygen concentrations, the oxygen removal rate switched to a much lower one. Anoxic conditions were observed after 4-20 days of incubation, depending on the experiment. The point at which the microbial community converted from aerobic respiration to anaerobic metabolism was distinct and was observed at an oxygen concentration of 0.26-1.41 mg/l, depending on the experiment. The experiments were accompanied by bacterial counts and analyses of ciliate communities. The study indicates how the disappearance of oxygen during anoxic zone formation should be modeled, and provides data on the oxygen removal rates associated with aerobic and anaerobic communities of microorganisms. DOI: http://dx.doi.org/10.5281/zenodo.144357

Dynamics of oxygen consumption during the formation of the anoxic zone in aquatic environment

Anoxic environments and communities of anaerobic organisms are encountered in aquatic environments and biotechnological reactors. Because of their importance, they are continuously studied. In this study, the dynamics of oxygen removal were observed during experiments reproducing the formation of the anoxic zone. Seven experiments were performed in an aquarium (volume: 60 l) with bottom sediments and water collected from different aquatic environments (river, pond, eutrophic lake, sea). To exclude reaeration, the water was isolated from the air by a layer of liquid paraffin. Below the paraffin layer the water was periodically mixed with a stirrer and sampled for oxygen concentration. Initially, a high rate of oxygen consumption was observed. Later, at low oxygen concentrations, the oxygen removal rate switched to a much lower one. Anoxic conditions were observed after 4-20 days of incubation, depending on the experiment. The point at which the microbial community converted from aerobic respiration to anaerobic metabolism was distinct and was observed at an oxygen concentration of 0.26-1.41 mg/l, depending on the experiment. The experiments were accompanied by bacterial counts and analyses of ciliate communities. The study indicates how the disappearance of oxygen during anoxic zone formation should be modeled, and provides data on the oxygen removal rates associated with aerobic and anaerobic communities of microorganisms. DOI: http://dx.doi.org/10.5281/zenodo.144357

Systems for grading the strength of recommendations in clinical practice guidelines in oncology

Introduction. In order to improve the applicability of clinical practice guidelines, their authors assign recommendations with grades denoting the degree of conviction regarding their practical application. Nevertheless even within one branch of medicine, significant differences between the grading systems arise. Material and methods. To identify these systems, websites of societies and institutions publishing oncology guidelines were searched. Only high-quality, regularly updated guidelines were included. Results. Five systems were analysed – all incorporate quality of evidence and strength of recommendation, but vary in the methods of their assessment and structure of the scales. Discussion. The described systems depend on the review of data, the quality of which supports the ascribed strength. Systems differ with regard to the methods of assessing the quality, quantity and consistency of evidence, potentially leading to assigning different grades of strength to recommendations based on the same studies. Conclusions. The introduction of unified grading systems across each branch of medicine could aid the development of unambiguous recommendations that are easy to introduce within the healthcare system

Consensus on methods of development of clinical practice guidelines in oncology under the auspices of Maria Sklodowska-Curie National Research Institute of Oncology and the Agency for Health Technology Assessment and Tariff System

Introduction.As the changes leading to improvement of cancer care in Poland have shown the need to introduce clinical practice guidelines into the health care system, it has become clear that no methodological standard of the process for guidelines preparation has been established so far. The following process aims to present a unified and comprehensive clinical practice guidelines (CPGs) development methodology. Materials and methods.A review of globally recognised methods used by guideline development groups was prepared, informing the discussion during three plenary meetings and extensive consultations in writing. The resulting document was unanimously approved by a group of 24 methodologists and clinical experts, and has been formally recognized as a standard for CPGs development by the management of the National Institute of Oncology and the Agency for Health Technology Assessment and Tariff System. Results.Within the process, 43 recommendations were formulated to create unified and comprehensive rules for guideline development within the Polish healthcare system. Conclusions.The presented methods are consistent with the globally recognized tools and methods of guideline development, such as GRADE and ADAPTE, and follow quality criteria described by AGREE II. The process supports the development of high-quality guidelines within a resource-constrained setting by allowing to choose between adoption, adaptation, or de novo development of either the whole document of guidelines or particular recommendations

Planktonic communities in a small post-peat reservoir (Ustka Forest District, Poland)

The aim of this study was to evaluate the present state of a small (area of 0.2 ha), shallow (mean depth of 2 m) and approximately 30-year-old post-peat reservoir located in Bruskowskie Bagno, a Baltic raised mire in northern Poland. The study was conducted during all seasons of the year (August 2019–July 2020). The reservoir was characterised by a yellow to brown water colour, low pH (5.4) and quite low conductivity (40.4 µS cm-1), which are the main features of dystrophic water bodies. Similar to natural, dystrophic lakes and ponds, the phytoplankton was mainly composed of mixotrophic species like Dinobryon sp. and Gonyostomum semen. The only numerous non-flagellate group within the phytoplankton was desmids, which indicated that the water was influenced by the mire. The reservoir was characterised by a high abundance of ciliates (annual mean of 55.6 cells ml-1) and a very high abundance of rotifers (annual mean of 3.72 ind. ml-1). Among ciliates, the most important were prostomatids, accounting for 53% of the mean annual ciliate abundance. The results of our study indicate that artificial, approximately 30-year-old, post-peat reservoir resembled a natural dystrophic water body

Dynamics of oxygen consumption during the formation of the anoxic zone in aquatic environment

Anoxic environments and communities of anaerobic organisms are encountered in aquatic environments and biotechnological reactors. Because of their importance, they are continuously studied. In this study, the dynamics of oxygen removal were observed during experiments reproducing the formation of the anoxic zone. Seven experiments were performed in an aquarium (volume: 60 l) with bottom sediments and water collected from different aquatic environments (river, pond, eutrophic lake, sea). To exclude reaeration, the water was isolated from the air by a layer of liquid paraffin. Below the paraffin layer the water was periodically mixed with a stirrer and sampled for oxygen concentration. Initially, a high rate of oxygen consumption was observed. Later, at low oxygen concentrations, the oxygen removal rate switched to a much lower one. Anoxic conditions were observed after 4-20 days of incubation, depending on the experiment. The point at which the microbial community converted from aerobic respiration to anaerobic metabolism was distinct and was observed at an oxygen concentration of 0.26-1.41 mg/l, depending on the experiment. The experiments were accompanied by bacterial counts and analyses of ciliate communities. The study indicates how the disappearance of oxygen during anoxic zone formation should be modeled, and provides data on the oxygen removal rates associated with aerobic and anaerobic communities of microorganisms. DOI: http://dx.doi.org/10.5281/zenodo.144357

Systems for grading the strength of recommendations in clinical practice guidelines in oncology

Introduction. In order to improve the applicability of clinical practice guidelines, their authors assign recommendations with grades denoting the degree of conviction regarding their practical application. Nevertheless even within one branch of medicine, significant differences between the grading systems arise. Material and methods. To identify these systems, websites of societies and institutions publishing oncology guidelines were searched. Only high-quality, regularly updated guidelines were included. Results. Five systems were analysed – all incorporate quality of evidence and strength of recommendation, but vary in the methods of their assessment and structure of the scales. Discussion. The described systems depend on the review of data, the quality of which supports the ascribed strength. Systems differ with regard to the methods of assessing the quality, quantity and consistency of evidence, potentially leading to assigning different grades of strength to recommendations based on the same studies. Conclusions. The introduction of unified grading systems across each branch of medicine could aid the development of unambiguous recommendations that are easy to introduce within the healthcare system

Consensus on methods of development of clinical practice guidelines in oncology under the auspices of Maria Sklodowska-Curie National Research Institute of Oncology and the Agency for Health Technology Assessment and Tariff System

Introduction.As the changes leading to improvement of cancer care in Poland have shown the need to introduce clinical practice guidelines into the health care system, it has become clear that no methodological standard of the process for guidelines preparation has been established so far. The following process aims to present a unified and comprehensive clinical practice guidelines (CPGs) development methodology. Materials and methods.A review of globally recognised methods used by guideline development groups was prepared, informing the discussion during three plenary meetings and extensive consultations in writing. The resulting document was unanimously approved by a group of 24 methodologists and clinical experts, and has been formally recognized as a standard for CPGs development by the management of the National Institute of Oncology and the Agency for Health Technology Assessment and Tariff System. Results.Within the process, 43 recommendations were formulated to create unified and comprehensive rules for guideline development within the Polish healthcare system. Conclusions.The presented methods are consistent with the globally recognized tools and methods of guideline development, such as GRADE and ADAPTE, and follow quality criteria described by AGREE II. The process supports the development of high-quality guidelines within a resource-constrained setting by allowing to choose between adoption, adaptation, or de novo development of either the whole document of guidelines or particular recommendations

Wide‐Angle Seismic Imaging of Two Modes of Crustal Accretion in Mature Atlantic Ocean Crust

We present a high‐resolution 2‐D P‐wave velocity model from a 225‐km‐long active seismic profile, collected over ~60–75 Ma central Atlantic crust. The profile crosses five ridge segments separated by a transform and three nontransform offsets. All ridge discontinuities share similar primary characteristics, independent of the offset. We identify two types of crustal segment. The first displays a classic two‐layer velocity structure with a high gradient Layer 2 (~0.9 s−1) above a lower gradient Layer 3 (0.2 s−1). Here, PmP coincides with the 7.5 km s−1 contour, and velocity increases to >7.8 km s−1 within 1 km below. We interpret these segments as magmatically robust, with PmP representing a petrological boundary between crust and mantle. The second has a reduced contrast in velocity gradient between the upper and lower crust and PmP shallower than the 7.5 km s−1 contour. We interpret these segments as tectonically dominated, with PmP representing a serpentinized (alteration) front. While velocity‐depth profiles fit within previous envelopes for slow‐spreading crust, our results suggest that such generalizations give a misleading impression of uniformity. We estimate that the two crustal styles are present in equal proportions on the floor of the Atlantic. Within two tectonically dominated segments, we make the first wide‐angle seismic identifications of buried oceanic core complexes in mature (>20 Ma) Atlantic Ocean crust. They have a ~20‐km‐wide “domal” morphology with shallow basement and increased upper crustal velocities. We interpret their midcrustal seismic velocity inversions as alteration and rock‐type assemblage contrasts across crustal‐scale detachment faults