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We study the ART GALLERY Problem under k-hop visibility in polyominoes. In this visibility model, two unit squares of a polyomino can see each other if and only if the shortest path between the respective vertices in the dual graph of the polyomino has length at most k. In this paper, we show that the VC dimension of this problem is 3 in simple polyominoes, and 4 in polyominoes with holes. Furthermore, we provide a reduction from PLANAR MONOTONE 3SAT, thereby showing that the problem is NP-complete even in thin polyominoes (i.e., polyominoes that do not a contain a 2 x 2 block of cells). Complementarily, we present a linear-time 4-approximation algorithm for simple 2-thin polyominoes (which do not contain a 3 x 3 block of cells) for all k is an element of N., Funding Agencies|Swedish Research Council (Vetenskapsradet) [2021-03810, 2018-04001]; Sweden's innovation agency VINNOVA [2018-04101]

Many freight trains depart Swedish marshalling yards before or after their planned departure times. Today, a deviating departure time is allowed if no conflicting train path can be found a few stations ahead. This increases the risk that the train might be delayed to its destination and cause delays to other trains. We present a meta-heuristic that modifies a timetable by adding a train path (for our freight train) and, if necessary, adjusting surrounding train paths. The aim of the insertion of the additional train path and the adjustments of the existing ones is to obtain a large bottleneck robustness, that is, the largest possible minimal temporal distance to any other train in the timetable. We provide experimental results for a Swedish railway stretch with a non-cyclic timetable and heterogeneous traffic. We show that we quickly add a train path, while improving the robustness of the timetable., Funding Agencies|EU H2020 [826206, 881778]; Trafikverket [TRV 2018/63708, TRV 2019/7622]

We present an O(n2 · min{m, n}) time and O(n · min{m, n}) storage algorithm to compute the minsum set of m watchmen routes given their starting points in a Stiegl polygon ― a staircase polygon where the floor solely consists of one horizontal and one vertical edge ― with n vertices.

Many freight trains depart Swedish marshalling yards before or after their planned departure times. Today, a deviating departure time is allowed if no conflicting train path can be found a few stations ahead. This increases the risk that the train might be delayed to its destination and cause delays to other trains. We present a meta-heuristic that modifies a timetable by adding a train path (for our freight train) and, if necessary, adjusting surrounding train paths. The aim of the insertion of the additional train path and the adjustments of the existing ones is to obtain a large bottleneck robustness, that is, the largest possible minimal temporal distance to any other train in the timetable. We provide experimental results for a Swedish railway stretch with a non-cyclic timetable and heterogeneous traffic. We show that we quickly add a train path, while improving the robustness of the timetable., Funding Agencies|EU H2020 [826206, 881778]; Trafikverket [TRV 2018/63708, TRV 2019/7622]

This document constitutes Deliverable D2.3 of the project FR8RAIL III Work Package (WP) 2 “Real-Time Network Management” within the framework of the Technology Demonstrator - TD5.2 “Digital Transport Management” of IP5 “Technologies for Sustainable & Attractive European Rail Freight” in Shift2Rail. The report documents the conducted work and results from task T2.3 and is the final deliverable from WP2. Three methods and tools have been developed, analysed, and demonstrated on real-world operational data. These tools address three different but equally important aspects for improving the efficiency of real-time network management of railways and contribute to closing the gap between planning and operations by enabling the traffic management to have a more proactive way of working . The focus of the work is on the coordination of freight operations at lines and marshalling yards, namely: • Coordination of all operational activities taking place at arrival/departure yards. • Replanning of timetables for line traffic. • Prediction of system effects and the combined operations of yards and lines. Firstly, an integrated demonstration platform for planning operational activities at a marshalling yard is studied. The developed Yard Coordination System (YCS) itself is described as well as how it has been applied and demonstrated in a workshop with experienced participants from the three principally involved stakeholders. The demonstration has shown that a tool like YCS can improve transparency and enable cooperative and pro-active planning. The practitioners reckoned that the tool could prevent and alleviate departure delays, and they expressed a strong wish for continued development of such support. An extensive list of experiences, development suggestions, potentials and risks are reported. Secondly, a timetable modification module (TIMO) for short-term replanning of line traffic is evaluated. The method uses a heuristic approach that aims at achieving a high bottle, FR8RAIL III

Spiral Galaxies is a pencil-and-paper puzzle played on a grid of unit squares: given a set of points called centers, the goal is to partition the grid into polyominoes such that each polyomino contains exactly one center and is 180 degrees rotationally symmetric about its center. We show that this puzzle is NP-complete, ASP-complete, and #P-complete even if (a) all solutions to the puzzle have rectangles for polyominoes; or (b) the polyominoes are required to be rectangles and all solutions to the puzzle have just 1 x 1, 1 x 3, and 3 x 1 rectangles. The proof for the latter variant also implies NP/ASP/#P-completeness of finding a noncrossing perfect matching in distance-2 grid graphs where edges connect vertices of Euclidean distance 2. Moreover, we prove NP-completeness of the design problem of minimizing the number of centers such that there exists a set of galaxies that exactly cover a given shape.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Spiral Galaxies is a pencil-and-paper puzzle played on a grid of unit squares: given a set of points called centers, the goal is to partition the grid into polyominoes such that each polyomino contains exactly one center and is 180 degrees rotationally symmetric about its center. We show that this puzzle is NP-complete, ASP-complete, and #P-complete even if (a) all solutions to the puzzle have rectangles for polyominoes; or (b) the polyominoes are required to be rectangles and all solutions to the puzzle have just 1 x 1, 1 x 3, and 3 x 1 rectangles. The proof for the latter variant also implies NP/ASP/#P-completeness of finding a noncrossing perfect matching in distance-2 grid graphs where edges connect vertices of Euclidean distance 2. Moreover, we prove NP-completeness of the design problem of minimizing the number of centers such that there exists a set of galaxies that exactly cover a given shape.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Spiral Galaxies is a pencil-and-paper puzzle played on a grid of unit squares: given a set of points called centers, the goal is to partition the grid into polyominoes such that each polyomino contains exactly one center and is 180 degrees rotationally symmetric about its center. We show that this puzzle is NP-complete, ASP-complete, and #P-complete even if (a) all solutions to the puzzle have rectangles for polyominoes; or (b) the polyominoes are required to be rectangles and all solutions to the puzzle have just 1 x 1, 1 x 3, and 3 x 1 rectangles. The proof for the latter variant also implies NP/ASP/#P-completeness of finding a noncrossing perfect matching in distance-2 grid graphs where edges connect vertices of Euclidean distance 2. Moreover, we prove NP-completeness of the design problem of minimizing the number of centers such that there exists a set of galaxies that exactly cover a given shape.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Many freight trains depart Swedish marshalling yards before or after their planned departure times. Today, a deviating departure time is allowed if no conflicting train path can be found a few stations ahead. This increases the risk that the train might be delayed to its destination and cause delays to other trains. We present a meta-heuristic that modifies a timetable by adding a train path (for our freight train) and, if necessary, adjusting surrounding train paths. The aim of the insertion of the additional train path and the adjustments of the existing ones is to obtain a large bottleneck robustness, that is, the largest possible minimal temporal distance to any other train in the timetable. We provide experimental results for a Swedish railway stretch with a non-cyclic timetable and heterogeneous traffic. We show that we quickly add a train path, while improving the robustness of the timetable., Funding Agencies|EU H2020 [826206, 881778]; Trafikverket [TRV 2018/63708, TRV 2019/7622]

We present an O(n2 · min{m, n}) time and O(n · min{m, n}) storage algorithm to compute the minsum set of m watchmen routes given their starting points in a Stiegl polygon ― a staircase polygon where the floor solely consists of one horizontal and one vertical edge ― with n vertices.

Many freight trains depart Swedish marshalling yards before or after their planned departure times. Today, a deviating departure time is allowed if no conflicting train path can be found a few stations ahead. This increases the risk that the train might be delayed to its destination and cause delays to other trains. We present a meta-heuristic that modifies a timetable by adding a train path (for our freight train) and, if necessary, adjusting surrounding train paths. The aim of the insertion of the additional train path and the adjustments of the existing ones is to obtain a large bottleneck robustness, that is, the largest possible minimal temporal distance to any other train in the timetable. We provide experimental results for a Swedish railway stretch with a non-cyclic timetable and heterogeneous traffic. We show that we quickly add a train path, while improving the robustness of the timetable., Funding Agencies|EU H2020 [826206, 881778]; Trafikverket [TRV 2018/63708, TRV 2019/7622]

Many freight trains depart Swedish marshalling yards before or after their planned departure times. Today, a deviating departure time is allowed if no conflicting train path can be found a few stations ahead. This increases the risk that the train might be delayed to its destination and cause delays to other trains. We present a meta-heuristic that modifies a timetable by adding a train path (for our freight train) and, if necessary, adjusting surrounding train paths. The aim of the insertion of the additional train path and the adjustments of the existing ones is to obtain a large bottleneck robustness, that is, the largest possible minimal temporal distance to any other train in the timetable. We provide experimental results for a Swedish railway stretch with a non-cyclic timetable and heterogeneous traffic. We show that we quickly add a train path, while improving the robustness of the timetable., Funding Agencies|EU H2020 [826206, 881778]; Trafikverket [TRV 2018/63708, TRV 2019/7622]

This study is about rescheduling freight trains to reduce the eff ects of major interruptions. In this paper, we consider that the interruption is an unexpected marshallingyard closure. We develop a macroscopic Mixed-Integer Linear Programming (MILP)model to reschedule railway timetables. One important principle is that we simultaneously reschedule several trains, instead of one-by-one. Furthermore, we consider arescheduling strategy of letting trains wait on the way when the destination yard havea closure. The model considers stopping restrictions and the capacity of each segmentand station. The order of the trains aff ected by the interruption is not fi xed. We presentexperimental results of three diff erent cases, which are all based on artifi cial data.

We consider the watchman route problem for a k-transmitter watchman: standing at point p in a polygon P, the watchman can see if intersects P’s boundary at most k times—q is k-visible to p. Traveling along the k-transmitter watchman route, either all points in P or a discrete set of points must be k-visible to the watchman. We aim for minimizing the length of the k-transmitter watchman route. We show that even in simple polygons the shortest k-transmitter watchman route problem for a discrete set of points is NP-complete and cannot be approximated to within a logarithmic factor (unless P=NP), both with and without a given starting point. Moreover, we present a polylogarithmic approximation for the k-transmitter watchman route problem for a given starting point and with approximation ratio (with)., Funding agencies: Supported by grants 2018-04001 (Nya paradigmer för autonom obemannad flygledning) and 2021-03810 (Illuminate: bevisbart goda algoritmer för bevakningsproblem) from the Swedish Research Council (Vetenskapsrådet).

This study is about rescheduling freight trains to reduce the effects of major interruptions. In this paper, we consider that the interruption is an unexpected marshalling-yard closure. We develop a macroscopic Mixed-Integer Linear Programming (MILP) model to reschedule railway timetables. One important principle is that we simultaneously reschedule several trains, instead of one-by-one. Furthermore, we consider a rescheduling strategy of letting trains wait on the way when the destination yard have a closure. The model considers stopping restrictions and the capacity of each segment and station. The order of the trains affected by the interruption is not fixed. We present experimental results of three different cases, which are all based on artificial data.

Train dispatchers monitor and control train traffi c from a dispatching center, which isresponsible for a certain region in the railway network. This region is divided into subareas, where each train dispatcher controls one or several subareas at any time. Giventhe high safety concerns of their profession, dispatchers’ working shifts should fulfi lseveral legal and operational constraints, such as bounds on the length of shifts andon the resting periods between shifts. To construct shift schedules for train dispatchers is a complex and time-consuming process that is currently done manually. In thispaper, we present an optimization framework to automate this process, based on amodel for single-day shifts. Here, we focus on the objective of minimizing the numberof dispatchers as a baseline for future objectives. We present experimental results forreal-world sized data (number of geographical areas and train movements in the orderof magnitude as for one dispatching center in Sweden, covering the southern partof the country). We study the impact on the run time for diff erent input parameters,namely: the total number of geographical areas, the maximum number of geographical areas that can be assigned to a dispatcher in any period, changes in adjacencybetween the geographical areas, and the number of geographical areas that eachdispatcher is qualifi ed to monitor. The run time for the instances is between 19 and305 seconds

Spiral Galaxies is a pencil-and-paper puzzle played on a grid of unit squares: given a set of points called centers, the goal is to partition the grid into polyominoes such that each polyomino contains exactly one center and is 180 degrees rotationally symmetric about its center. We show that this puzzle is NP-complete, ASP-complete, and #P-complete even if (a) all solutions to the puzzle have rectangles for polyominoes; or (b) the polyominoes are required to be rectangles and all solutions to the puzzle have just 1 x 1, 1 x 3, and 3 x 1 rectangles. The proof for the latter variant also implies NP/ASP/#P-completeness of finding a noncrossing perfect matching in distance-2 grid graphs where edges connect vertices of Euclidean distance 2. Moreover, we prove NP-completeness of the design problem of minimizing the number of centers such that there exists a set of galaxies that exactly cover a given shape.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Spiral Galaxies is a pencil-and-paper puzzle played on a grid of unit squares: given a set of points called centers, the goal is to partition the grid into polyominoes such that each polyomino contains exactly one center and is 180 degrees rotationally symmetric about its center. We show that this puzzle is NP-complete, ASP-complete, and #P-complete even if (a) all solutions to the puzzle have rectangles for polyominoes; or (b) the polyominoes are required to be rectangles and all solutions to the puzzle have just 1 x 1, 1 x 3, and 3 x 1 rectangles. The proof for the latter variant also implies NP/ASP/#P-completeness of finding a noncrossing perfect matching in distance-2 grid graphs where edges connect vertices of Euclidean distance 2. Moreover, we prove NP-completeness of the design problem of minimizing the number of centers such that there exists a set of galaxies that exactly cover a given shape.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

We propose a new approach to evaluate ocular measurements of air traffic controllers (ATCOs) as potential workload and fatigue indicators. We employ the Fast Fourier transform (FFT) to test our assumption that humans respond to increasing fatigue with harmonic oscillations in the eye movement, while they respond to increasingly high workload with disruptions to these harmonic oscillations. The FFT yields the frequency spectrum and we suggest to use the center of gravity of this spectrum to capture the variations. We give a proof-of concept study to evaluate our approach and we were able to verify our hypotheses in some cases, in particular, we identify the fixation duration as a promising indicator of changes in workload.

We study the Art Gallery Problem under $k$-hop visibility in polyominoes. In this visibility model, two unit squares of a polyomino can see each other if and only if the shortest path between the respective vertices in the dual graph of the polyomino has length at most $k$. In this paper, we show that the VC dimension of this problem is $3$ in simple polyominoes, and $4$ in polyominoes with holes. Furthermore, we provide a reduction from Planar Monotone 3Sat, thereby showing that the problem is NP-complete even in thin polyominoes (i.e., polyominoes that do not a contain a $2\times 2$ block of cells). Complementarily, we present a linear-time $4$-approximation algorithm for simple $2$-thin polyominoes (which do not contain a $3\times 3$ block of cells) for all $k\in \mathbb{N}$., Comment: 17 pages, 11 figures. Full version of an extended abstract that has been accepted to LATIN 2024. Some parts have been improved based on reviewer comments

Numerous studies have examined the impact of the COVID-19 pandemic on alcohol use changes in Europe, with concerns raised regarding increased use and related harms. Approach. We synthesised observational studies published between 1 January 2020 and 31 September 2021 on self-reported changes in alcohol use associated with COVID-19. Electronic databases were searched for studies evaluating individual data from European general and clinical populations. We identified 646 reports, of which 56 general population studies were suitable for random-effects meta-analyses of proportional differences in alcohol use changes. Variations by time, sub-region and study quality were assessed in subsequent meta-regressions. Additional 16 reports identified were summarised narratively. Key Findings. Compiling reports measuring changes in overall alcohol use, slightly more individuals indicated a decrease than an increase in their alcohol use during the pandemic [3.8%, 95% confidence interval (CI) 0.00–7.6%]. Decreases were also reported more often than increases in drinking frequency (8.0%, 95% CI 2.7–13.2%), quantity consumed (12.2%, 95% CI 8.3–16.2%) and heavy episodic drinking (17.7%, 95% CI 13.6–21.8%). Among people with pre-existing high drinking levels/alcohol use disorder, high-level drinking patterns appear to have solidified or intensified. Implications. Pandemic-related changes in alcohol use may be associated with pre-pandemic drinking levels. Increases among high-risk alcohol users are concerning, suggesting a need for ongoing monitoring and support from relevant health-care services. Conclusion. Our findings suggest that more people reduced their alcohol use in Europe than increased it since the onset of the pandemic. However high-quality studies examining specific change mechanisms at the population level are lacking.

Background AIDS and drug aid facilities offer a low-threshold access for people with injecting and other forms of drug use and thus play a central role in reducing hepatitis C virus (HCV) infections in this high-risk group. The aim of this study is to describe the provision and barriers of HCV-specific measures in facilities with low-threshold services for drug users in Germany. Method The cross-sectional survey addressed facility structures, availability of HCV-specific measures (prevention, testing, diagnostics, therapy), structural, facility-related and patient-related barriers. The allocation of consumer paraphernalia was used as a criterion for the selection of facilities with low-threshold access for people with injecting and other forms of drug use. The data analysis was carried out descriptively by summarizing and analyzing facilities based on their characteristics. Results Of the 380 facilities contacted, responses from 135 facilities with low-threshold access for people with injecting and other forms of drug use were included in the analysis. Most of the facilities offer information on safer use (98.5%) and HCV-counselling (87.4 %). Around 28% of the facilities have HCV antibody or rapid tests available. 40% and 64.4% of all facilities stated that clients with a positive antibody test result or with a corresponding diagnosis (e.g. chronic HCV infection) can be referred to medical care. Insufficient funding and client-related barriers (e.g. lack of reliability) were mentioned as the main barriers to improving the implementation of HCV-specific measures. Conclusions While general HCV-prevention measures are an integral part of low-threshold services for drug users in Germany, the availability and uptake of HCV testing and HCV care services for people with injecting and other forms of drug use is not sufficient to significantly reduce HCV infections in this high-risk group. In addition to adequate funding, client-centered interventions are needed to improve t, Hintergrund Einrichtungen der Aids- und Drogenhilfe bieten einen niedrigschwelligen Zugang für Menschen mit injizierendem und anderen Drogenkonsumformen und spielen somit eine zentrale Rolle für die Eindämmung von Hepatitis C Virus (HCV)-Infektionen in dieser Hochrisikogruppe. Ziel dieser Studie ist es, die Versorgungsleistungen sowie Barrieren von HCV-spezifischen Maßnahmen in Einrichtungen der Aids- und Drogenhilfe mit niedrigschwelligen Angeboten in Deutschland zu beschreiben. Methode Die Querschnittsbefragung adressierte Einrichtungsstrukturen, Verfügbarkeit von HCV-spezifischen Maßnahmen (Prävention, Testung, Diagnostik, Therapie), strukturelle, einrichtungsbezogene und patient:innenbezogene Barrieren. Die Vergabe von Konsumutensilien wurde als Kriterium für die Auswahl von Einrichtungen mit einem niedrigschwelligen Zugang für Menschen mit injizierendem und anderen Drogenkonsumformen herangezogen. Die Datenanalyse erfolgte deskriptiv, indem Einrichtungen anhand ihrer Merkmale zusammengefasst, beschrieben und analysiert wurden. Ergebnisse Von 380 kontaktierten Einrichtungen gingen Antworten von 135 Einrichtungen mit einer Vergabe von Konsumutensilien in die Auswertung ein. Der Großteil der Einrichtungen bot Informationen zu „Safer Use“ (98,5%) und Beratungen zu HCV (87,4%) an. Etwa 28% der Einrichtungen verfügten über HCV-Antikörper bzw. Schnelltestangebote. 40% bzw. 64,4% aller Einrichtungen gaben an, dass Klient:innen mit einem positiven Antikörpertestergebnis bzw. mit einer entsprechenden Diagnose (z. B. chronische HCV-Infektion) in die medizinische Versorgung weitervermittelt werden können. Als Hauptbarrieren für eine verbesserte Umsetzung von HCV-spezifischen Maßnahmen wurden ungenügende Finanzierung und klient:innenbezogene Barrieren (z. B. mangelnde Zuverlässigkeit) genannt. Schlussfolgerungen Während Maßnahmen zur HCV-Prävention integraler Bestandteil der niedrigschwelligen Drogenhilfe sind, ist die Verfügbarkeit und Inanspruchnahme von HCV-Test- und Ver

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in LeKieffre, C., Jauffrais, T., Bernhard, J., Filipsson, H., Schmidt, C., Roberge, H., Maire, O., Panieri, G., Geslin, E., & Meibom, A. Ammonium and sulfate assimilation is widespread in benthic foraminifera. Frontiers in Marine Science, 9, (2022): 861945, https://doi.org/10.3389/fmars.2022.861945., Nitrogen and sulfur are key elements in the biogeochemical cycles of marine ecosystems to which benthic foraminifera contribute significantly. Yet, cell-specific assimilation of ammonium, nitrate and sulfate by these protists is poorly characterized and understood across their wide range of species-specific trophic strategies. For example, detailed knowledge about ammonium and sulfate assimilation pathways is lacking and although some benthic foraminifera are known to maintain intracellular pools of nitrate and/or to denitrify, the potential use of nitrate-derived nitrogen for anabolic processes has not been systematically studied. In the present study, NanoSIMS isotopic imaging correlated with transmission electron microscopy was used to trace the incorporation of isotopically labeled inorganic nitrogen (ammonium or nitrate) and sulfate into the biomass of twelve benthic foraminiferal species from different marine environments. On timescales of twenty hours, no detectable 15N-enrichments from nitrate assimilation were observed in species known to perform denitrification, indicating that, while denitrifying foraminifera store intra-cellular nitrate, they do not use nitrate-derived nitrogen to build their biomass. Assimilation of both ammonium and sulfate, with corresponding 15N and 34S-enrichments, were observed in all species investigated (with some individual exceptions for sulfate). Assimilation of ammonium and sulfate thus can be considered widespread among benthic foraminifera. These metabolic capacities may help to underpin the ability of benthic foraminifera to colonize highly diverse marine habitats., This work was supported by the Swiss National Science Foundation (grant no. 200021_149333), and a postdoctoral fellowship allowed to CL by the University Loire-Bretagne. SBB sampling was funded by US National Science Foundation grant BIO IOS 1557430 to JMB, who also acknowledges NASA grant #80NSSC21K0478 for partial support. HF acknowledges funding from the Swedish Research Council VR (grant number 2017-04190). Svalbard sampling was supported by the Research Council of Norway through CAGE (Center for Excellence in Arctic Gas Hydrate Environment and Climate, project number 223259) and NORCRUST (project number 255150) to GP and the fellowship MOPGA (Make Our Planet Great Again) by CAMPUS France to CS.

Weather affects the work of air traffic controllers, however, for staff scheduling in Remote Tower Centers (RTCs) it has not been taken into account. We study the impact of various weather phenomena on air traffic controller (ATCO) taskload through structured interviews with ATCOs. We deduce taskload-driven impact factors and the corresponding thresholds for the intensity of the weather phenomena at several Swedish airports. To account for the uncertainty in the weather prediction, we obtain probabilistic weather data from Ensemble Prediction Systems (EPSs). Then we adjust our prior Mixed Integer Programming (MIP) model for RTC staff scheduling to account for uncertain impactful weather occurrences and yield a distribution for the necessary number of ATCOs for RTC staff scheduling. Our framework can be used for conventional towers as well. We quantify the impact of weather by comparing the number of controllers necessary to operate at five Swedish airports from a remote tower during two example days in 2020, with and without taking weather events into account. In our calculations we use historical weather and flight data to show that ignoring weather impact may lead to significant understaffing at a RTC., Funding Agencies|Swedish Transport Administration (Trafikverket); SESAR JU under the European Union [783287]

Weather affects the work of air traffic controllers, however, for staff scheduling in Remote Tower Centers (RTCs) it has not been taken into account. We study the impact of various weather phenomena on air traffic controller (ATCO) taskload through structured interviews with ATCOs. We deduce taskload-driven impact factors and the corresponding thresholds for the intensity of the weather phenomena at several Swedish airports. To account for the uncertainty in the weather prediction, we obtain probabilistic weather data from Ensemble Prediction Systems (EPSs). Then we adjust our prior Mixed Integer Programming (MIP) model for RTC staff scheduling to account for uncertain impactful weather occurrences and yield a distribution for the necessary number of ATCOs for RTC staff scheduling. Our framework can be used for conventional towers as well. We quantify the impact of weather by comparing the number of controllers necessary to operate at five Swedish airports from a remote tower during two example days in 2020, with and without taking weather events into account. In our calculations we use historical weather and flight data to show that ignoring weather impact may lead to significant understaffing at a RTC., Funding Agencies|Swedish Transport Administration (Trafikverket); SESAR JU under the European Union [783287]

Nitrogen and sulfur are key elements in the biogeochemical cycles of marine ecosystems to which benthic foraminifera contribute significantly. Yet, cell-specific assimilation of ammonium, nitrate and sulfate by these protists is poorly characterized and understood across their wide range of species-specific trophic strategies. For example, detailed knowledge about ammonium and sulfate assimilation pathways is lacking and although some benthic foraminifera are known to maintain intracellular pools of nitrate and/or to denitrify, the potential use of nitrate-derived nitrogen for anabolic processes has not been systematically studied. In the present study, NanoSIMS isotopic imaging correlated with transmission electron microscopy was used to trace the incorporation of isotopically labeled inorganic nitrogen (ammonium or nitrate) and sulfate into the biomass of twelve benthic foraminiferal species from different marine environments. On timescales of twenty hours, no detectable 15N-enrichments from nitrate assimilation were observed in species known to perform denitrification, indicating that, while denitrifying foraminifera store intra-cellular nitrate, they do not use nitrate-derived nitrogen to build their biomass. Assimilation of both ammonium and sulfate, with corresponding 15N and 34S-enrichments, were observed in all species investigated (with some individual exceptions for sulfate). Assimilation of ammonium and sulfate thus can be considered widespread among benthic foraminifera. These metabolic capacities may help to underpin the ability of benthic foraminifera to colonize highly diverse marine habitats.

Weather affects the work of air traffic controllers, however, for staff scheduling in Remote Tower Centers (RTCs) it has not been taken into account. We study the impact of various weather phenomena on air traffic controller (ATCO) taskload through structured interviews with ATCOs. We deduce taskload-driven impact factors and the corresponding thresholds for the intensity of the weather phenomena at several Swedish airports. To account for the uncertainty in the weather prediction, we obtain probabilistic weather data from Ensemble Prediction Systems (EPSs). Then we adjust our prior Mixed Integer Programming (MIP) model for RTC staff scheduling to account for uncertain impactful weather occurrences and yield a distribution for the necessary number of ATCOs for RTC staff scheduling. Our framework can be used for conventional towers as well. We quantify the impact of weather by comparing the number of controllers necessary to operate at five Swedish airports from a remote tower during two example days in 2020, with and without taking weather events into account. In our calculations we use historical weather and flight data to show that ignoring weather impact may lead to significant understaffing at a RTC., Funding Agencies|Swedish Transport Administration (Trafikverket); SESAR JU under the European Union [783287]

Nitrogen and sulfur are key elements in the biogeochemical cycles of marine ecosystems to which benthic foraminifera contribute significantly. Yet, cell-specific assimilation of ammonium, nitrate and sulfate by these protists is poorly characterized and understood across their wide range of species-specific trophic strategies. For example, detailed knowledge about ammonium and sulfate assimilation pathways is lacking and although some benthic foraminifera are known to maintain intracellular pools of nitrate and/or to denitrify, the potential use of nitrate-derived nitrogen for anabolic processes has not been systematically studied. In the present study, NanoSIMS isotopic imaging correlated with transmission electron microscopy was used to trace the incorporation of isotopically labeled inorganic nitrogen (ammonium or nitrate) and sulfate into the biomass of twelve benthic foraminiferal species from different marine environments. On timescales of twenty hours, no detectable 15N-enrichments from nitrate assimilation were observed in species known to perform denitrification, indicating that, while denitrifying foraminifera store intra-cellular nitrate, they do not use nitrate-derived nitrogen to build their biomass. Assimilation of both ammonium and sulfate, with corresponding 15N and 34S-enrichments, were observed in all species investigated (with some individual exceptions for sulfate). Assimilation of ammonium and sulfate thus can be considered widespread among benthic foraminifera. These metabolic capacities may help to underpin the ability of benthic foraminifera to colonize highly diverse marine habitats.

Numerous studies have examined the impact of the COVID-19 pandemic on alcohol use changes in Europe, with concerns raised regarding increased use and related harms. Approach. We synthesised observational studies published between 1 January 2020 and 31 September 2021 on self-reported changes in alcohol use associated with COVID-19. Electronic databases were searched for studies evaluating individual data from European general and clinical populations. We identified 646 reports, of which 56 general population studies were suitable for random-effects meta-analyses of proportional differences in alcohol use changes. Variations by time, sub-region and study quality were assessed in subsequent meta-regressions. Additional 16 reports identified were summarised narratively. Key Findings. Compiling reports measuring changes in overall alcohol use, slightly more individuals indicated a decrease than an increase in their alcohol use during the pandemic [3.8%, 95% confidence interval (CI) 0.00–7.6%]. Decreases were also reported more often than increases in drinking frequency (8.0%, 95% CI 2.7–13.2%), quantity consumed (12.2%, 95% CI 8.3–16.2%) and heavy episodic drinking (17.7%, 95% CI 13.6–21.8%). Among people with pre-existing high drinking levels/alcohol use disorder, high-level drinking patterns appear to have solidified or intensified. Implications. Pandemic-related changes in alcohol use may be associated with pre-pandemic drinking levels. Increases among high-risk alcohol users are concerning, suggesting a need for ongoing monitoring and support from relevant health-care services. Conclusion. Our findings suggest that more people reduced their alcohol use in Europe than increased it since the onset of the pandemic. However high-quality studies examining specific change mechanisms at the population level are lacking.

We study the art gallery problem for opposing half guards: guards that can either see to their left or to their right only. We present art gallery theorems, show that the location of half guards in 2-guardable polygons is not restricted to extensions, show that the problem is NP-hard in monotone polygons, and present approximation algorithms for spiral and staircase polygons., Comment: 17 pages, 12 figures. A preliminary version was published in the 34th Canadian Conference on Computational Geometry (CCCG 2022)

We study the art gallery problem for opposing halfguards: guards that can either see to their left or to theirright only. We present art gallery theorems, show thatthe problem is NP-hard in monotone polygons, presentapproximation algorithms for spiral and staircase poly-gons, and show that the location of half guards in 2-guardable polygons is not restricted to extensions.

Weather affects the work of air traffic controllers, however, for staff scheduling in Remote Tower Centers (RTCs) it has not been taken into account. We study the impact of various weather phenomena on air traffic controller (ATCO) taskload through structured interviews with ATCOs. We deduce taskload-driven impact factors and the corresponding thresholds for the intensity of the weather phenomena at several Swedish airports. To account for the uncertainty in the weather prediction, we obtain probabilistic weather data from Ensemble Prediction Systems (EPSs). Then we adjust our prior Mixed Integer Programming (MIP) model for RTC staff scheduling to account for uncertain impactful weather occurrences and yield a distribution for the necessary number of ATCOs for RTC staff scheduling. Our framework can be used for conventional towers as well. We quantify the impact of weather by comparing the number of controllers necessary to operate at five Swedish airports from a remote tower during two example days in 2020, with and without taking weather events into account. In our calculations we use historical weather and flight data to show that ignoring weather impact may lead to significant understaffing at a RTC., Funding Agencies|Swedish Transport Administration (Trafikverket); SESAR JU under the European Union [783287]

Weather affects the work of air traffic controllers, however, for staff scheduling in Remote Tower Centers (RTCs) it has not been taken into account. We study the impact of various weather phenomena on air traffic controller (ATCO) taskload through structured interviews with ATCOs. We deduce taskload-driven impact factors and the corresponding thresholds for the intensity of the weather phenomena at several Swedish airports. To account for the uncertainty in the weather prediction, we obtain probabilistic weather data from Ensemble Prediction Systems (EPSs). Then we adjust our prior Mixed Integer Programming (MIP) model for RTC staff scheduling to account for uncertain impactful weather occurrences and yield a distribution for the necessary number of ATCOs for RTC staff scheduling. Our framework can be used for conventional towers as well. We quantify the impact of weather by comparing the number of controllers necessary to operate at five Swedish airports from a remote tower during two example days in 2020, with and without taking weather events into account. In our calculations we use historical weather and flight data to show that ignoring weather impact may lead to significant understaffing at a RTC., Funding Agencies|Swedish Transport Administration (Trafikverket); SESAR JU under the European Union [783287]

We consider the watchman route problem for a $k$-transmitter watchman: standing at point $p$ in a polygon $P$, the watchman can see $q\in P$ if $\overline{pq}$ intersects $P$'s boundary at most $k$ times -- $q$ is $k$-visible to $p$. Traveling along the $k$-transmitter watchman route, either all points in $P$ or a discrete set of points $S\subset P$ must be $k$-visible to the watchman. We aim for minimizing the length of the $k$-transmitter watchman route. We show that even in simple polygons the shortest $k$-transmitter watchman route problem for a discrete set of points $S\subset P$ is NP-complete and cannot be approximated to within a logarithmic factor (unless P=NP), both with and without a given starting point. Moreover, we present a polylogarithmic approximation for the $k$-transmitter watchman route problem for a given starting point and $S\subset P$ with approximation ratio $O(\log^2(|S|\cdot n) \log\log (|S|\cdot n) \log(|S|+1))$ (with $|P|=n$)., Comment: 14 pages, 6 figures; conference proceedings WALCOM 2022: https://link.springer.com/chapter/10.1007/978-3-031-27051-2_18; updated with some notation changes and minor edits

Die FDG-Positronenemissionstomographie/Computertomographie (PET/CT) ist ein hilfreiches Diagnostikum im Bereich des fortgeschrittenen malignen Melanoms. Doch aufgrund der relativ unspezifischen Anreicherung von FDG in allen glukoseumsetzenden Organen sind unklare Befunde oder sogar falsch positive Befunde, trotz optimaler Patientenvorbereitung, keine Seltenheit. Anhand einer exemplarischen Fallserie soll diese Arbeit den Leser im Hinblick auf diese Thematik sensibilisieren und das Auftreten falsch positiver Befunde in der PET/CT-Interpretation in der Melanombildgebung folglich reduziert werden., FDG positron emission tomography/computed tomography (PET/CT) is a powerful diagnostic tool in advanced melanoma, but due to the relatively unspecific tracer uptake of FDG in all organs that are processing glucose, unclear results or even false positive results are not uncommon despite ideal preparation of patients. By reference to an exemplary case series, this dissertation shall sensitize to this topic and consequently reduce the occurrence of false positive results in PET/CT interpretation in melanoma imaging.

We present an algorithm to insert a train path in an existing railway timetable close to operation, when we want to affect the existing (passenger) traffic as little as possible. Thus, we consider all other trains as fixed, and aim for a resulting train path that maximizes the bottleneck robustness, that is, a train path that maximizes the temporal distance to neighboring trains in the timetable. Our algorithm is based on a graph formulation of the problem and uses a variant of Dijkstra’s algorithm. We present an extensive experimental evaluation of our algorithm for the Swedish railway stretch from Malmö to Hallsberg. Moreover, we analyze the size of our constructed graph., Funding agency: Linköping University, Shift2Rail

We present an algorithm to insert a train path in an existing railway timetable close to operation, when we want to affect the existing (passenger) traffic as little as possible. Thus, we consider all other trains as fixed, and aim for a resulting train path that maximizes the bottleneck robustness, that is, a train path that maximizes the temporal distance to neighboring trains in the timetable. Our algorithm is based on a graph formulation of the problem and uses a variant of Dijkstra’s algorithm. We present an extensive experimental evaluation of our algorithm for the Swedish railway stretch from Malmö to Hallsberg. Moreover, we analyze the size of our constructed graph., Funding agency: Linköping University, Shift2Rail

In this paper, we present a novel methodology to manage arrival traffic in terminal airspace. We define two areas around the airport, aiming to efficiently schedule incoming traffic. A four-dimensional (4D) trajectory negotiation/synchronization process between the air traffic control officer (ATCO) and the aircraft is performed in the pre-sequencing area, while the aircraft are still in the en-route phase of flight. On the other hand, in the dynamic-trajectories area, the ATCO, with the help of a ground support tool, generates dynamic arrival routes that automatically adapt to the current traffic demand. These arrival routes allow the aircraft to fly neutral continuous descent operations (CDOs, descents with idle thrust and no speed-brakes usage) and to ensure a separation throughout the arrival procedure. We choose a mixed-integer-programming approach to generate the arrival routes, while we formulate and solve an optimal control problem to generate a set of candidate CDOs per aircraft. Results show that, with a sufficient look-ahead time, it is possible to assign a required time of arrival (RTA) within each aircraft-arrival time window that would allow to efficiently schedule traffic even in the most challenging and dense scenarios. Besides improving efficiency of current operations in terminal airspace, the methodology presented in this paper could become a technical enabler towards an extended arrival manager (E-AMAN) with extended capabilities and, ultimately, to a fully deployed trajectory based operations (TBO) environment.

In this paper, we present a novel methodology to manage arrival traffic in terminal airspace. We define two areas around the airport, aiming to efficiently schedule incoming traffic. A four-dimensional (4D) trajectory negotiation/synchronization process between the air traffic control officer (ATCO) and the aircraft is performed in the pre-sequencing area, while the aircraft are still in the en-route phase of flight. On the other hand, in the dynamic-trajectories area, the ATCO, with the help of a ground support tool, generates dynamic arrival routes that automatically adapt to the current traffic demand. These arrival routes allow the aircraft to fly neutral continuous descent operations (CDOs, descents with idle thrust and no speed-brakes usage) and to ensure a separation throughout the arrival procedure. We choose a mixed-integer-programming approach to generate the arrival routes, while we formulate and solve an optimal control problem to generate a set of candidate CDOs per aircraft. Results show that, with a sufficient look-ahead time, it is possible to assign a required time of arrival (RTA) within each aircraft-arrival time window that would allow to efficiently schedule traffic even in the most challenging and dense scenarios. Besides improving efficiency of current operations in terminal airspace, the methodology presented in this paper could become a technical enabler towards an extended arrival manager (E-AMAN) with extended capabilities and, ultimately, to a fully deployed trajectory based operations (TBO) environment.

In this paper, we present a novel methodology to manage arrival traffic in terminal airspace. We define two areas around the airport, aiming to efficiently schedule incoming traffic. A four-dimensional (4D) trajectory negotiation/synchronization process between the air traffic control officer (ATCO) and the aircraft is performed in the pre-sequencing area, while the aircraft are still in the en-route phase of flight. On the other hand, in the dynamic-trajectories area, the ATCO, with the help of a ground support tool, generates dynamic arrival routes that automatically adapt to the current traffic demand. These arrival routes allow the aircraft to fly neutral continuous descent operations (CDOs, descents with idle thrust and no speed-brakes usage) and to ensure a separation throughout the arrival procedure. We choose a mixed-integer-programming approach to generate the arrival routes, while we formulate and solve an optimal control problem to generate a set of candidate CDOs per aircraft. Results show that, with a sufficient look-ahead time, it is possible to assign a required time of arrival (RTA) within each aircraft-arrival time window that would allow to efficiently schedule traffic even in the most challenging and dense scenarios. Besides improving efficiency of current operations in terminal airspace, the methodology presented in this paper could become a technical enabler towards an extended arrival manager (E-AMAN) with extended capabilities and, ultimately, to a fully deployed trajectory based operations (TBO) environment.

We present an algorithm to insert a train path in an existing railway timetable close to operation, when we want to affect the existing (passenger) traffic as little as possible. Thus, we consider all other trains as fixed, and aim for a resulting train path that maximizes the bottleneck robustness, that is, a train path that maximizes the temporal distance to neighboring trains in the timetable. Our algorithm is based on a graph formulation of the problem and uses a variant of Dijkstra’s algorithm. We present an extensive experimental evaluation of our algorithm for the Swedish railway stretch from Malmö to Hallsberg. Moreover, we analyze the size of our constructed graph., Funding agency: Linköping University, Shift2Rail

We present an algorithm to insert a train path in an existing railway timetable close to operation, when we want to affect the existing (passenger) traffic as little as possible. Thus, we consider all other trains as fixed, and aim for a resulting train path that maximizes the bottleneck robustness, that is, a train path that maximizes the temporal distance to neighboring trains in the timetable. Our algorithm is based on a graph formulation of the problem and uses a variant of Dijkstra’s algorithm. We present an extensive experimental evaluation of our algorithm for the Swedish railway stretch from Malmö to Hallsberg. Moreover, we analyze the size of our constructed graph., Funding agency: Linköping University, Shift2Rail

Spiral Galaxies is a pencil-and-paper puzzle played on a grid of unit squares: given a set of points called centers, the goal is to partition the grid into polyominoes such that each polyomino contains exactly one center and is 180{\deg} rotationally symmetric about its center. We show that this puzzle is NP-complete, ASP-complete, and #P-complete even if (a) all solutions to the puzzle have rectangles for polyominoes; or (b) the polyominoes are required to be rectangles and all solutions to the puzzle have just 1$\times$1, 1$\times$3, and 3$\times$1 rectangles. The proof for the latter variant also implies NP/ASP/#P-completeness of finding a noncrossing perfect matching in distance-2 grid graphs where edges connect vertices of Euclidean distance 2. Moreover, we prove NP-completeness of the design problem of minimizing the number of centers such that there exists a set of galaxies that exactly cover a given shape, Comment: 24 pages, 24 figures. Thorough revision including new Section 2 proof which handles the promise problem

© 2018 World Scientific Publishing Company. We study the problem of folding a polyomino P into a polycube Q, allowing faces of Q to be covered multiple times. First, we define a variety of folding models according to whether the folds (a) must be along grid lines of P or can divide squares in half (diagonally and/or orthogonally), (b) must be mountain or can be both mountain and valley, (c) can remain flat (forming an angle of 180°), and (d) must lie on just the polycube surface or can have interior faces as well. Second, we give all the inclusion relations among all models that fold on the grid lines of P. Third, we characterize all polyominoes that can fold into a unit cube, in some models. Fourth, we give a linear-time dynamic programming algorithm to fold a tree-shaped polyomino into a constant-size polycube, in some models. Finally, we consider the triangular version of the problem, characterizing which polyiamonds fold into a regular tetrahedron.

In this paper, we present a novel methodology to manage arrival traffic in terminal airspace. We define two areas around the airport, aiming to efficiently schedule incoming traffic. A four-dimensional (4D) trajectory negotiation/synchronization process between the air traffic control officer (ATCO) and the aircraft is performed in the pre-sequencing area, while the aircraft are still in the en-route phase of flight. On the other hand, in the dynamic-trajectories area, the ATCO, with the help of a ground support tool, generates dynamic arrival routes that automatically adapt to the current traffic demand. These arrival routes allow the aircraft to fly neutral continuous descent operations (CDOs, descents with idle thrust and no speed-brakes usage) and to ensure a separation throughout the arrival procedure. We choose a mixed-integer-programming approach to generate the arrival routes, while we formulate and solve an optimal control problem to generate a set of candidate CDOs per aircraft. Results show that, with a sufficient look-ahead time, it is possible to assign a required time of arrival (RTA) within each aircraft-arrival time window that would allow to efficiently schedule traffic even in the most challenging and dense scenarios. Besides improving efficiency of current operations in terminal airspace, the methodology presented in this paper could become a technical enabler towards an extended arrival manager (E-AMAN) with extended capabilities and, ultimately, to a fully deployed trajectory based operations (TBO) environment.