We investigated how seston fatty acids (FA) and water temperature explained seasonal variation in cladoceran and copepod FA over three years in pre-alpine, oligotrophic Lake Lunz, Austria. Using the ...mostly algal-derived polyunsaturated FA (PUFA: arachidonic, ARA; eicosapentaenoic, EPA; docosahexaenoic acid, DHA), terrestrial FA (TFA, 22 : 0, 24 : 0), and bacterial FA (BAFA, 15 : 0, 17 : 0 and their branched homologues) as source-specific biomarkers, we show that cladocerans consistently contained more ARA and EPA and copepods more DHA than the available food (seston). None of these physiologically important PUFA were significantly related between zooplankton and seston across the entire study period but copepod DHA increased with seston DHA during the coldest months (< 8°C, based on a significant seston FA*temperature interaction). EPA, conversely, increased with decreasing water temperature in both zooplankton groups. For the nonessential FA, TFA were lower in zooplankton than in seston and not related to dietary supply or water temperature. However, cladoceran and copepod BAFA increased significantly with increasing seston BAFA and decreasing water temperature. These findings suggest that physiological regulation in response to changing water temperature had a significant impact on cladoceran and copepod EPA and the extent of dietary tracking for copepod DHA. TFA available in the seston may not have been consumed or were poorly incorporated by zooplankton, but BAFA were good indicators of available resources throughout multiple seasonal cycles. Based on our study, both FA type and water temperature impact the extent that dietary vs. nondietary processes govern cladoceran and copepod FA in oligotrophic lakes.
Longitudinal and lateral connectivity is important for mobile aquatic species in rivers for reproductive migrations, recruitment, gene flow and access to food resources across habitat types. Water ...resource developments such as dams and levees may disrupt these connections, causing river fragmentation and loss of access to highly productive habitats such as floodplain wetlands. We used sulfur stable isotopes as a tracer to estimate patterns of fish movement in an unregulated river in tropical northern Australia, taking advantage of observed spatial variation in sulfur isotope values of their food resources across the catchment. We also modelled the flow and barrier related impacts of potential dam development scenarios on fish movement. Fish with isotope values significantly different from local prey values were determined to be migrants. In the ‘no dams’ scenario, movement varied among fish species (0–44% migrant fish within species where n > 5) and sites (0–40% migrant fish within sites where n > 5), and immigration was higher in more connected sites. Impacts of water resource development on fish movement varied between dam scenarios, with predictions that a dam on the main channel of the Mitchell River would have the highest impact of the three individual dam scenarios. This study provides critical information on how flow-mediated connectivity supports patterns of fish community movement in an unregulated river system. The generic quantitative approach of combining tracers of fish movement with connectivity modelling provides a powerful predictive tool. While we used sulfur stable isotopes to estimate fish movement, our approach can be used with other tracers of movement such as otoliths and acoustic telemetry, making it widely applicable to guide sustainable development in other river systems.
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•We used sulfur stable isotopes to study fish movement in a tropical river system.•Fish movement varied spatially across the river system with changes in connectivity.•We developed a method for predicting impacts of potential dams on fish movement.•The location of the dam influenced the severity of the impact on fish movement.•This quantitative method is a tool that can be used to guide sustainable development.
The aim of this study was to assess metabolic pathways for arachidonic acid (20:4n-6) biosynthesis in
Daphnia magna
. Neonates of
D. magna
were maintained on
13
C enriched
Scenedesmus obliquus
and ...supplemented with liposomes that contained separate treatments of unlabeled docosapentaenoic acid (22:5n-6), 20:4n-6, linoleic acid (18:2n-6) or oleic acid (18:1n-9).
Daphnia
in the control treatment, without any supplementary fatty acids (FA) containing only trace amounts of 20:4n-6 (~0.3 % of all FA). As expected, the highest proportion of 20:4n-6 (~6.3 %) was detected in
Daphnia
that received liposomes supplemented with this FA. Higher availability of 18:2n-6 in the diet increased the proportion of 18:2n-6 in
Daphnia,
but the proportion of 20:4n-6 was not affected.
Daphnia
supplemented with 22:5n-6 contained ~3.5 % 20:4n-6 in the lipids and FA specific stable isotope analyses validated that the increase in the proportion of 20:4n-6 was due to retroconversion of unlabeled 22:5n-6. These results suggest that chain shortening of 22:5n-6 is a more efficient pathway to synthesize 20:4n-6 in
D. magna
than elongation and desaturation of 18:2n-6. These results may at least partially explain the discrepancies noticed between phytoplankton FA composition and the expected FA composition in freshwater cladocerans. Finally, retroconversion of dietary 22:5n-6 to 20:4n-6 indicates
Daphnia
efficiently retain long chain n-6 FA in lake food webs, which might be important for the nutritional ecology of fish.
Radio frequency (RF) shimming is a widely used method to improve the MRI quality by adjusting the magnitude and phase of the transmit elements in the RF coil and eliminating the field inhomogeneity ...in 3T MRI system. This process alters the field distribution inside the MRI borehole and changes both the level and location of the absorbed RF energy in patients. It is necessary to assess the impact of RF shimming on the risk of RF-induced heating for patients especially those who have implantable longitude medical electrodes in place during the MRI procedure. This paper investigates the impacts of RF shimming on the RF-induced heating of a generic pacemaker electrode using a transfer function method. Two different shimming schemes were studied. The first excitation scheme was designed to obtain a homogeneous B 1 + field in the image region-chest region. The second condition maximized the temperature rise around the generic pacemaker electrode with different implant trajectories. All the results were normalized to 2 W/kg average whole-body specific absorption rate (SAR) and a Q-matrices method was used to improve the SAR calculation efficiency. The average temperature rise at the electrode tip under quadrature excitation was 3.7 °C while under optimized excitation was 2.3 °C. The worst-case temperature rise for a selected trajectory was found to be 33.17 °C, which was almost 6 times of the temperature rise under quadrature excitation. Therefore, the RF-shimming condition can significantly change the RF-induced heating of electrodes. To ensure patient safety under MRI, RF-shimming condition should be considered and thoroughly integrated into the RF heating assessment.
Abstract Colorado’s High Plains stand at anomalously high elevations (~1300–2100 m) for their continental interior setting, but when and why this region became elevated is poorly understood. The ...Cenozoic history of the High Plains is also likely linked with that of the Rocky Mountains, where the timing and cause(s) of uplift are similarly debated. We present apatite (U-Th)/He (AHe) data for 10 samples from Tertiary intrusives along a ~200 km west-to-east transect across the High Plains of southeastern Colorado to constrain the timing of exhumation and to gain insight into when and why regional elevation gain occurred. Mean sample AHe dates for the ~24–22 Ma East Spanish Peak pluton and associated radial dikes from the westernmost High Plains are 18.8 ± 1.4 to 14.1 ± 1.7 Ma, recording substantial postemplacement erosion. AHe results for the mafic to ultramafic Apishapa Dikes (oldest ~37 Ma, youngest ~14 Ma) located ~20–40 km farther north and east on the High Plains range from 12.0 ± 1.4 to 6.2 ± 1.9 Ma, documenting continued exhumation on the western High Plains during the ~12–5 Ma deposition of the Ogallala Formation farther east and suggesting that the western limit of Ogallala deposition was east of the Apishapa Dikes. In far southeastern Colorado, the Two Buttes lamprophyre was emplaced at 36.8 ± 0.4 Ma and yields a Late Oligocene AHe date of 27.1 ± 4 Ma. Here, the Ogallala Formation unconformably overlies Two Buttes, indicating that the regional ~12 Ma age for the base of the Ogallala is a minimum age for the exposure of the pluton at the surface. The AHe data presented here document that kilometer-scale erosion affected all of the southeastern Colorado High Plains in Oligo-Miocene time. While exhumation can have multiple possible causes, we favor contemporaneous surface uplift capable of elevating the region to modern heights.
Here we present a mass spectrometric system specifically developed for the analysis of ultra-low-level tritium by the 3 He ingrowth method. The system was designed and developed in the Isotope ...Hydrology Laboratory of the International Atomic Energy Agency and consists of an off-line water degassing unit to remove pre-existing 3 He from sample water and a mass spectrometer system (Thermo Fisher Helix SFT) with a gas purification and separation system. The mass spectrometer system is equipped with a gas pipette system that inlets calibrated amounts of 3 He (99.995% 3 He spike) to accurately calibrate the mass spectrometer's sensitivity. The procedural blank level of 3 He in our system is extremely low and on the order of 10 −17 cm 3 STP, which enables us to quantify tritium in water samples (100 cm 3 ) as low as 0.05 TU with an ingrowth time of 2 months. Quantification of even lower tritium levels are possible by loading more water and/or by increasing the ingrowth time ( e.g. , 0.01 TU with 400 cm 3 water stored for 4 months). We analysed a set of water samples from the Tritium Intercomparison Exercise by IAEA (TRIC 2018) and confirmed that our data were consistent with the expected values. We have also confirmed that our analysis of natural groundwater samples agree well with the data obtained by the conventional liquid scintillation counting (LSC) method.
Here we present a mass spectrometric system specifically developed for the analysis of ultra-low-level tritium by the
3
He ingrowth method. The system was designed and developed in the Isotope ...Hydrology Laboratory of the International Atomic Energy Agency and consists of an off-line water degassing unit to remove pre-existing
3
He from sample water and a mass spectrometer system (Thermo Fisher Helix SFT) with a gas purification and separation system. The mass spectrometer system is equipped with a gas pipette system that inlets calibrated amounts of
3
He (99.995%
3
He spike) to accurately calibrate the mass spectrometer's sensitivity. The procedural blank level of
3
He in our system is extremely low and on the order of 10
−17
cm
3
STP, which enables us to quantify tritium in water samples (100 cm
3
) as low as 0.05 TU with an ingrowth time of 2 months. Quantification of even lower tritium levels are possible by loading more water and/or by increasing the ingrowth time (
e.g.
, 0.01 TU with 400 cm
3
water stored for 4 months). We analysed a set of water samples from the Tritium Intercomparison Exercise by IAEA (TRIC 2018) and confirmed that our data were consistent with the expected values. We have also confirmed that our analysis of natural groundwater samples agree well with the data obtained by the conventional liquid scintillation counting (LSC) method.
This work will describe a system to quantify ultra-low-level tritium concentrations in ∼100 mL water samples. Tritium decays into
3
He, thus we can take advantage of high sensitivity noble gas mass spectrometry.
Abstract
Issue/problem
In 2017, Austria started the establishment of multi-professional primary health care units (PCUs) to better meet patients’ and healthcare professionals’ needs including a focus ...on health promotion, health literacy and patients with chronic diseases. Currently, Austria has 40 operational PCUs. In the province of Styria, the quality of care in PCUs is monitored through quality indicators (QI) in annual surveys. The patient questionnaire includes items on patient satisfaction, shared decision-making, and self-management. The PCU team questionnaire covers organizational routines and working satisfaction.
Description of the problem
Only few improvement initiatives were launched in response to the QI surveys, especially for low-performing QI. In addition, the concept of quality indicators seemed difficult for the teams to understand. As a result, from 2021 on, the surveys are being conducted every other year. In the intervening years, PCU teams get the opportunity to discuss and reflect on the previous yeaŕs results in facilitated workshops.
Results
We held workshops in the ten PCUs in Styria from October 2022 to February 2023. In the workshops, the teams identified six strengths (e.g. providing a wide range of services) and six weaknesses (e.g. appointment coordination) of the PCUs with corresponding actions for improvement (e.g. managing the patient flow).
Lessons
Combining the QI surveys with workshops lead to practical actions for quality improvement as well as a better understanding of the relevance of quality indicators among PCU teams and funders. Workshops provided the teams with a dedicated space for reflecting on organizational processes, which they may not have the opportunity to do amidst their heavy workload and still adjusting to PCU structures.
Key messages
• Engaging the PCU teams in the quality improvement process ensures that the resulting actions are more relevant to their needs and priorities.
• Our quality indicators as well as the identified actions for quality improvement are highly transferable to other primary care settings and countries.
MRI induced heating on PM leads is a very complex issue. The widely varying results described in literature suggest that there are many factors that influence the degree of heating and that not ...always are adequately addressed by existing testing methods.
We present a wide database of experimental measurements of the heating of metallic wires and PM leads in a 1.5 T RF coil. The aim of these measurements is to systematically quantify the contribution of some potential factors involved in the MRI induced heating: the length and the geometric structure of the lead; the implant location within the body and the lead path; the shape of the phantom used to simulate the human trunk and its relative position inside the RF coil.
We found that the several factors are the primary influence on heating at the tip. Closer locations of the leads to the edge of the phantom and to the edge of the coil produce maximum heating. The lead length is the other crucial factor, whereas the implant area does not seem to have a major role in the induced temperature increase. Also the lead structure and the geometry of the phantom revealed to be elements that can significantly modify the amount of heating.
Our findings highlight the factors that have significant effects on MRI induced heating of implanted wires and leads. These factors must be taken into account by those who plan to study or model MRI heating of implants. Also our data should help those who wish to develop guidelines for defining safe medical implants for MRI patients. In addition, our database of the entire set of measurements can help those who wish to validate their numerical models of implants that may be exposed to MRI systems.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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