An approach to combine radar and gauge based rainfall data under consideration of their qualities in low mountain ranges of Saxony

An approach to combine gauge and radar data and additional quality information is presented. The development was focused on the improvement of the diagnostic for temporal (one hour) and spatial (1×1 km<sup>2</sup>) highly resolved precipitation data. The method is embedded in an online tool and was applied to the target area Saxony, Germany. The aim of the tool is to provide accurate spatial rainfall estimates. The results can be used for rainfall run-off modelling, e.g. in a flood management system. <br><br> Quality information allows a better assessment of the input data and the resulting precipitation field. They are stored in corresponding fields and represent the static and dynamic uncertainties of radar and gauge data. Objective combination of various precipitation and quality fields is realised using a cost function. <br><br> The findings of cross validation reveal that the proposed combination method merged the benefits and disadvantages of interpolated gauge and radar data and leads to mean estimates. The sampling point validation implies that the presented method slightly overestimated the areal rain as well as the high rain intensities in case of convective and advective events, while the results of pure interpolation method performed better. In general, the use of presented cost function avoids false rainfall amount in areas of low input data quality and improves the reliability in areas of high data quality. It is obvious that the combined product includes the small-scale variability of radar, which is seen as the important benefit of the presented combination approach. Local improvements of the final rain field are possible due to consideration of gauges that were not used for radar calibration, e.g. in topographic distinct regions

Modelling users in networks with path choice: four studies in telecommunications and transit

Networks of interacting users arise in many important modelling applications. Commuters interact with each other and form traffic jams during peak-time. Network protocols are users in a communication network that control sending rate and server choice. When protocols send with too high rates, network links get overloaded resulting in lost data and high delays. Although these two example users seem very different, they are similar on a conceptual modelling level. Accurate user models are essential to study complex interactions in networks. The behaviour of a user with access to different paths in a network can be modelled as an optimisation problem. Users who choose paths with the highest utility are common in many different application areas, for example road traffic, Internet protocol modelling, and general societal networks, i.e. networks of humans in everyday life. Optimisation-based user models are also attractive from the perspective of a modeller since they often allow the derivation of insights about the behaviour of the entire system by only describing a user model. The aim of this thesis is to show, in four practical studies from telecommunications and transit networks, where optimisation-based models have limitations when modelling users with path choice. We study users who have access to a limited number of paths in large scale data centers and investigate how many paths per user are realistically needed in order to get high throughput in the network. In multimedia streaming, we study a protocol that streams data on multiple paths and path properties matter. We also investigate complex energy models for data interfaces on mobile phones and evaluate how to switch interfaces to save energy. Finally, we analyse a long-term data set from 20,000 transit commuters and give insights on how they change their travel behaviour in response to incentives and targeted offers. We use tools from optimisation, simulation, and statistics to evaluate the four studies and point out problems we faced when modelling and implementing the system. The findings of this thesis indicate where user models need to be extended in order to be of practical use. The results can serve as a guide towards better user models for future modelling applications

Use of past precipitation data for regionalisation of hourly rainfall in the low mountain ranges of saxony, germany

Within the context of flood forecasting we deal with the improvement of regionalisation methods for the generation of highly resolved (1 h, 1x1km(2)) precipitation fields, which can be used as input for rainfall-runoff models or for verification of weather forecasts. Although radar observations of precipitation are available in many regions, it might be necessary to apply regionalisation methods near real-time for the cases that radar is not available or observations are of low quality. The aim of this paper is to investigate whether past precipitation information can be used to improve regionalisation of rainfall. Within a case study we determined typical precipitation Background-Fields (BGF) for the mountainous and hilly regions of Saxony using hourly and daily rain gauge data. Additionally, calibrated radar data served as past information for the BGF generation. For regionalisation of precipitation we used de-trended kriging and compared the results with another kriging based regionalisation method and with Inverse Distance Weighting (IDW). The performance of the methods was assessed by applying cross-validation, by inspection and by evaluation with rainfall-runoff simulations. The regionalisation of rainfall yielded better results in case of advective events than in case of convective events. The performance of the applied regionalisation methods showed no significant disagreement for different precipitation types. Cross-validation results were rather similar in most cases. Subjectively judged, the BGF-method reproduced best the structures of rain cells. Precipitation input derived from radar or kriging resulted in a better matching between observed and simulated flood hydrographs. Simple techniques like IDW also deliver satisfying results in some occasions. Implementation of past radar data into the BGF-method rendered no improvement, because of data shortages. Thus, no method proved to outperform the others generally. The decision, which method is appropriate for an event, should be made objectively using cross-validation, but also subjectively, using the expert knowledge of the forecaster.BMBF/0330700

Efficacy, safety, and pharmacokinetics of the anti-programmed cell death receptor-1 (PD-1) monoclonal antibody, tislelizumab (BGB-A317) in a phase 2, open-label, multicenter study to investigate in patients with unresectable hepatocellular carcinoma - Trial in progress.

n/

Impacts of Social Distancing Policies on Mobility and COVID-19 Case Growth in the US

Social distancing remains an important strategy to combat the COVID-19 pandemic in the United States. However, the impacts of specific state-level policies on mobility and subsequent COVID-19 case trajectories have not been completely quantified. Using anonymized and aggregated mobility data from opted-in Google users, we found that state-level emergency declarations resulted in a 9.9% reduction in time spent away from places of residence. Implementation of one or more social distancing policies resulted in an additional 24.5% reduction in mobility the following week, and subsequent shelter-in-place mandates yielded an additional 29.0% reduction. Decreases in mobility were associated with substantial reductions in case growth 2 to 4 weeks later. For example, a 10% reduction in mobility was associated with a 17.5% reduction in case growth 2 weeks later. Given the continued reliance on social distancing policies to limit the spread of COVID-19, these results may be helpful to public health officials trying to balance infection control with the economic and social consequences of these policies.Comment: Co-first Authors: GAW, SV, VE, and AF contributed equally. Corresponding Author: Dr. Evgeniy Gabrilovich, [email protected] 32 pages (including supplemental material), 4 figures in the main text, additional figures in the supplemental materia

Modeling the interactions between river morphodynamics and riparian vegetation

The study of river-riparian vegetation interactions is an important and intriguing research field in geophysics. Vegetation is an active element of the ecological dynamics of a floodplain which interacts with the fluvial processes and affects the flow field, sediment transport, and the morphology of the river. In turn, the river provides water, sediments, nutrients, and seeds to the nearby riparian vegetation, depending on the hydrological, hydraulic, and geomorphological characteristic of the stream. In the past, the study of this complex theme was approached in two different ways. On the one hand, the subject was faced from a mainly qualitative point of view by ecologists and biogeographers. Riparian vegetation dynamics and its spatial patterns have been described and demonstrated in detail, and the key role of several fluvial processes has been shown, but no mathematical models have been proposed. On the other hand, the quantitative approach to fluvial processes, which is typical of engineers, has led to the development of several morphodynamic models. However, the biological aspect has usually been neglected, and vegetation has only been considered as a static element. In recent years, different scientific communities (ranging from ecologists to biogeographers and from geomorphologists to hydrologists and fluvial engineers) have begun to collaborate and have proposed both semiquantitative and quantitative models of river-vegetation interconnections. These models demonstrate the importance of linking fluvial morphodynamics and riparian vegetation dynamics to understand the key processes that regulate a riparian environment in order to foresee the impact of anthropogenic actions and to carefully manage and rehabilitate riparian areas. In the first part of this work, we review the main interactions between rivers and riparian vegetation, and their possible modeling. In the second part, we discuss the semiquantitative and quantitative models which have been proposed to date, considering both multi- and single-thread river

Electrical Actuation of Electrically Conducting and Insulating Droplets using AC and DC Voltages

Electrical actuation of liquid droplets at the microscale offers promising applications in the fields of microfluidics and lab-on-chip devices. Much prior research has targeted the electrical actuation of electrically conducting liquid droplets using dc voltages (classical electrowetting). Electrical actuation of conducting droplets using ac voltages and the actuation of insulating droplets (using dc or ac voltages) has remained relatively unexplored. This paper utilizes an energy-minimization-based analytical framework to study the electrical actuation of a liquid droplet (electrically conducting or insulating) under ac actuation. It is shown that the electromechanical regimes of classical electrowetting, electrowetting under ac actuation and insulating droplet actuation can be extracted from the generic electromechanical actuation framework, depending on the electrical properties of the droplet, the underlying dielectric layer and the frequency of the actuation voltage. This paper also presents experiments which quantify the influence of the ac frequency and the electrical properties of the droplet on its velocity under electrical actuation. The velocities of droplets moving between two parallel plates under ac actuation are experimentally measured; these velocities are then related to the actuation force on the droplet which is predicted by the electromechanical model developed in this work. It is seen that the droplet velocities are strongly dependent on the frequency of the ac actuation voltage; the cut-off ac frequency, above which the droplet fails to actuate, is experimentally determined and related to the electrical conductivity of the liquid. This paper then analyzes and directly compares the various electromechanical regimes for the actuation of droplets in microfluidic applications