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| 2. |
- Klionsky, Daniel J., et al.
(author)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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In: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Research review (peer-reviewed)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 3. |
- Brunner, Manuela Irene, et al.
(author)
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Bivariate analysis of floods in climate impact assessments
- 2018
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In: Science of the Total Environment. - : ELSEVIER SCIENCE BV. - 0048-9697 .- 1879-1026. ; 616-617, s. 1392-1403
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Journal article (peer-reviewed)abstract
- Climate impact studies regarding floods usually focus on peak discharges and a bivariate assessment of peak discharges and hydrograph volumes is not commonly included. A joint consideration of peak discharges and hydrograph volumes, however, is crucial when assessing flood risks for current and future climate conditions. Here, we present a methodology to develop synthetic design hydrographs for future climate conditions that jointly consider peak discharges and hydrograph volumes. First, change factors are derived based on a regional climate model and are applied to observed precipitation and temperature time series. Second, the modified time series are fed into a calibrated hydrological model to simulate runoff time series for future conditions. Third, these time series are used to construct synthetic design hydrographs. The bivariate flood frequency analysis used in the construction of synthetic design hydrographs takes into account the dependence between peak discharges and hydrograph volumes, and represents the shape of the hydrograph. The latter is modeled using a probability density function while the dependence between the design variables peak discharge and hydrograph volume is modeled using a copula. We applied this approach to a set of eight mountainous catchments in Switzerland to construct catchment-specific and season-specific design hydrographs for a control and three scenario climates. Our work demonstrates that projected climate changes have an impact not only on peak discharges but also on hydrograph volumes and on hydrograph shapes both at an annual and at a seasonal scale. These changes are not necessarily proportional which implies that climate impact assessments on future floods should consider more flood characteristics than just flood peaks.
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| 4. |
- Brunner, Manuela I., et al.
(author)
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Flood type specific construction of synthetic design hydrographs
- 2017
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In: Water resources research. - : AMER GEOPHYSICAL UNION. - 0043-1397 .- 1944-7973. ; 53:2, s. 1390-1406
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Journal article (peer-reviewed)abstract
- Accurate estimates of flood peaks, corresponding volumes, and hydrographs are required to design safe and cost-effective hydraulic structures. In this paper, we propose a statistical approach for the estimation of the design variables peak and volume by constructing synthetic design hydrographs for different flood types such as flash-floods, short-rain floods, long-rain floods, and rain-on-snow floods. Our approach relies on the fitting of probability density functions to observed flood hydrographs of a certain flood type and accounts for the dependence between peak discharge and flood volume. It makes use of the statistical information contained in the data and retains the process information of the flood type. The method was tested based on data from 39 mesoscale catchments in Switzerland and provides catchment specific and flood type specific synthetic design hydrographs for all of these catchments. We demonstrate that flood type specific synthetic design hydrographs are meaningful in flood-risk management when combined with knowledge on the seasonality and the frequency of different flood types.
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| 5. |
- Brunner, Manuela I., et al.
(author)
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Synthetic design hydrographs for ungauged catchments : a comparison of regionalization methods
- 2018
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In: Stochastic environmental research and risk assessment (Print). - : Springer Science and Business Media LLC. - 1436-3240 .- 1436-3259. ; 32:7, s. 1993-2023
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Journal article (peer-reviewed)abstract
- Design flood estimates for a given return period are required in both gauged and ungauged catchments for hydraulic design and risk assessments. Contrary to classical design estimates, synthetic design hydrographs provide not only information on the peak magnitude of events but also on the corresponding hydrograph volumes together with the hydrograph shapes. In this study, we tested different regionalization approaches to transfer parameters of synthetic design hydrographs from gauged to ungauged catchments. These approaches include classical regionalization methods such as linear regression techniques, spatial methods, and methods based on the formation of homogeneous regions. In addition to these classical approaches, we tested nonlinear regression models not commonly used in hydrological regionalization studies, such as random forest, bagging, and boosting. We found that parameters related to the magnitude of the design event can be regionalized well using both linear and nonlinear regression techniques using catchment area, length of the main channel, maximum precipitation intensity, and relief energy as explanatory variables. The hydrograph shape, however, was found to be more difficult to regionalize due to its high variability within a catchment. Such variability might be better represented by looking at flood-type specific synthetic design hydrographs.
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| 6. |
- Sikorska, Anna E., et al.
(author)
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Appropriate temporal resolution of precipitation data for discharge modelling in pre-alpine catchments
- 2018
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In: Hydrological Sciences Journal. - : TAYLOR & FRANCIS LTD. - 0262-6667 .- 2150-3435. ; 63:1, s. 1-16
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Journal article (peer-reviewed)abstract
- Precipitation time series with high temporal resolution are desired for hydrological modelling and flood studies. Yet the choice of an appropriate resolution is not straightforward because the use of too high a temporal resolution increases the data requirements, computational costs and, presumably, associated uncertainty, while performance improvement may be indiscernible. In this study, the effect of averaging hourly precipitation on model performance and associated uncertainty is investigated using two data sources: station network precipitation (SNP) and radar-based precipitation (RBP). From these datasets, time series of different temporal resolutions were generated, and runoff was simulated for 13 pre-alpine catchments with a bucket-type model. Our results revealed that different temporal resolutions were required for an acceptable model performance depending on the catchment size and data source. These were 1-12h for small (16-59km(2)), 3-21h for medium (60-200km(2)), and 24h for large (200-939km(2)) catchments.
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| 7. |
- Sikorska, Anna E., et al.
(author)
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Flood-type classification in mountainous catchments using crisp and fuzzy decision trees
- 2015
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In: Water resources research. - 0043-1397 .- 1944-7973. ; 51:10, s. 7959-7976
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Journal article (peer-reviewed)abstract
- Floods are governed by largely varying processes and thus exhibit various behaviors. Classification of flood events into flood types and the determination of their respective frequency is therefore important for a better understanding and prediction of floods. This study presents a flood classification for identifying flood patterns at a catchment scale by means of a fuzzy decision tree. Hence, events are represented as a spectrum of six main possible flood types that are attributed with their degree of acceptance. Considered types are flash, short rainfall, long rainfall, snow-melt, rainfall on snow and, in high alpine catchments, glacier-melt floods. The fuzzy decision tree also makes it possible to acknowledge the uncertainty present in the identification of flood processes and thus allows for more reliable flood class estimates than using a crisp decision tree, which identifies one flood type per event. Based on the data set in nine Swiss mountainous catchments, it was demonstrated that this approach is less sensitive to uncertainties in the classification attributes than the classical crisp approach. These results show that the fuzzy approach bears additional potential for analyses of flood patterns at a catchment scale and thereby it provides more realistic representation of flood processes.
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| 8. |
- Westerberg, Ida, et al.
(author)
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Hydrological model calibration with uncertain discharge data
- 2020
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In: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435.
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Journal article (peer-reviewed)abstract
- Discharge data used to calibrate and evaluate hydrological models can be highly uncertain and this uncertainty affects the conclusions that we can draw from modelling results. We investigated the role of discharge data uncertainty and its representation in hydrological model calibration to give recommendations on methods to account for data uncertainty. We tested five different representations of discharge data uncertainty in calibrating the HBV-model for three Swiss catchments, ranging from using no information to using full empirical probability distributions for each time step. We developed a new objective function to include discharge data uncertainty, as quantified by these distributions directly in calibration to hydrological time series. This new objective function provided more reliable results than using no data uncertainty or multiple realizations of discharge time series. We recommend using the new objective function in combination with empirical or triangular distributions of the discharge data uncertainty.
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