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In this paper, we evaluate the application of Bayesian Optimization (BO) to discrete event simulation (DES) models. In a first step, we create a simple model, for which we know the optimal set of parameter values in advance. We implement the model in SimPy, a framework for DES written in Python. We then interpret the simulation model as a black box function subject to optimization. We show that it is possible to find the optimal set of parameter values using the open source library GPyOpt. To enhance our evaluation, we create a second and more complex model. To better handle the complexity of the model, and to add a visual component, we build the second model in Simio, a commercial off-the-shelf simulation modeling tool. To apply BO to a model in Simio, we use the Simio API to write an extension for optimization plug-ins. This extension encapsulates the logic of the BO algorithm, which we deployed as a web service in the cloud.
The fact that simulation models are black box functions with regard to their behavior and the influence of their input parameters makes them an apparent candidate for Bayesian Optimization (BO). Simulation models are multivariable and stochastic, and their behavior is to a large extent unpredictable. In particular, we do not know for sure which input parameters to adjust to maximize (or minimize) the model’s outcome. In addition, the complex models can take a substantial amount of time to run.
Bayesian Optimization is a sequential and self-learning algorithm to optimize black box functions similar to as we find them in simulation models: they contain a set of parameters for which we want to identify the optimal set, they are expensive to evaluate, and they exhibit stochastic noise. BO has proven to efficiently optimize black box functions from varius disciplines. Among those, and most notably, it is successfully applied in machine learning algorithms to optimize hyperparameters.
SimBO is a flexible framework for optimizing discrete event-driven simulations (DES) using sequential optimization algorithms. While specifically designed for Bayesian Optimization (BO) in the context of DES, SimBO can be applied to any black-box problem with other optimization algorithms. The framework consists of four encapsulated components - the black-box problem, the sequential optimization algorithm, a database for experiment configuration and results, and a web-based graphical user interface - that communicate via well-defined interfaces. Each component can be run in different environments, allowing for cooperation between different hardware- and software configurations. In our research context, SimBO’s architecture enabled BO algorithms to be run on a high-performance cluster with GPU support, while the simulation is executed on a local Windows machine using the Simio simulation software. The framework’s flexibility also makes it suitable for evolving from a research-focused tool to a production-ready, cloud-based optimization tool for modern algorithms.
Introduction Postoperative delirium (POD) is seen in approximately 15% of elderly patients and is related to poorer outcomes. In 2017, the Federal Joint Committee (Gemeinsamer Bundesausschuss) introduced a ‘quality contract’ (QC) as a new instrument to improve healthcare in Germany. One of the four areas for improvement of in-patient care is the ‘Prevention of POD in the care of elderly patients’ (QC-POD), as a means to reduce the risk of developing POD and its complications.
The Institute for Quality Assurance and Transparency in Health Care identified gaps in the in-patient care of elderly patients related to the prevention, screening and treatment of POD, as required by consensus-based and evidence-based delirium guidelines. This paper introduces the QC-POD protocol, which aims to implement these guidelines into the clinical routine. There is an urgent need for well-structured, standardised and interdisciplinary pathways that enable the reliable screening and treatment of POD. Along with effective preventive measures, these concepts have a considerable potential to improve the care of elderly patients.
Methods and analysis The QC-POD study is a non-randomised, pre–post, monocentric, prospective trial with an interventional concept following a baseline control period. The QC-POD trial was initiated on 1 April 2020 between Charité-Universitätsmedizin Berlin and the German health insurance company BARMER and will end on 30 June 2023. Inclusion criteria: patients 70 years of age or older that are scheduled for a surgical procedure requiring anaesthesia and insurance with the QC partner (BARMER). Exclusion criteria included patients with a language barrier, moribund patients and those unwilling or unable to provide informed consent. The QC-POD protocol provides perioperative intervention at least two times per day, with delirium screening and non-pharmacological preventive measures.
Ethics and dissemination This protocol was approved by the ethics committee of the Charité-Universitätsmedizin, Berlin, Germany (EA1/054/20). The results will be published in a peer-reviewed scientific journal and presented at national and international conferences.
A brief questionnaire for measuring alarm fatigue in nurses and physicians in intensive care units
(2023)
When exposed to hundreds of medical device alarms per day, intensive care unit (ICU) staff can develop “alarm fatigue” (i.e., desensitisation to alarms). However, no standardised way of quantifying alarm fatigue exists. We aimed to develop a brief questionnaire for measuring alarm fatigue in nurses and physicians. After developing a list of initial items based on a literature review, we conducted 15 cognitive interviews with the target group (13 nurses and two physicians) to ensure that the items are face valid and comprehensible. We then asked 32 experts on alarm fatigue to judge whether the items are suited for measuring alarm fatigue. The resulting 27 items were sent to nurses and physicians from 15 ICUs of a large German hospital. We used exploratory factor analysis to further reduce the number of items and to identify scales. A total of 585 submissions from 707 participants could be analysed (of which 14% were physicians and 64% were nurses). The simple structure of a two-factor model was achieved within three rounds. The final questionnaire (called Charité Alarm Fatigue Questionnaire; CAFQa) consists of nine items along two scales (i.e., the “alarm stress scale” and the “alarm coping scale”). The CAFQa is a brief questionnaire that allows clinical alarm researchers to quantify the alarm fatigue of nurses and physicians. It should not take more than five minutes to administer.
The present study investigates consumers’ acceptance of Se-biofortified apples, as well as Se health and nutrition claims that have been approved by the European Commission. Despite indications that such statements are more likely to be accepted if the carrier product itself has a healthy image, unprocessed fruits biofortified with Se have not been investigated in this context yet. Apples as the most frequently-consumed type of fresh fruit in Germany may offer the potential to improve the Se status of consumers when the produce is enriched with Se. Therefore, an online survey of 356 German adults was conducted to analyze different aspects that could affect the perception of and preference for the proposed product concept by consumers. The findings indicate a moderate acceptance of Se-biofortified apples, as well as of Se health and nutrition claims among the participants. Additional information about beneficial health effects of Se had a significant impact on consumer acceptance. People who regularly eat convenience food and prefer to buy apples at supermarkets were particularly attracted by the product idea. In conclusion, the results of the study indicate good prospects for a successful introduction of Se-rich apples in the German food market, if the produce is advertised with approved health and nutrition claims.
The study aimed to investigate inactivation of naturally occurring microorganisms and quality of red pepper paste treated by high pressure processing (HPP). Central composite rotatable design was employed to determine the impacts of pressure (100–600 MPa) and holding time (30–600 s). HPP at 527 MPa for 517 s reduced aerobic mesophilic bacteria count by 4.5 log CFU/g. Yeasts and molds counts were reduced to 1 log CFU/g at 600 MPa for 315 s. Total phenols, carotenoids and antioxidants activity ranged from 0.28 to 0.33 g GAE/100 g, 96.0–98.4 mg βc/100 g and 8.70–8.95 μmol TE/g, respectively. Increase (2.5–6.7%) in these variables was observed with increasing pressure and holding time. Total color difference (ΔE∗) values (0.2–2.8) were within the ranges of ‘imperceptible’ to ‘noticeable’. Experimental results were fitted satisfactorily into quadratic model with higher R2 values (0.8619–0.9863). Optimization process suggested treatment of red pepper paste at 536 MPa for 125 s for maximum desirability (0.622). Validation experiments confirmed comparable percentage of relative errors. Overall, this technique could be considered as an efficient treatment for the inactivation of microorganisms that naturally occur in red pepper paste with minimal changes in its characteristics.
Red pepper (Capsicum annuum L.) is one of the major spices consumed globally, recognized for its aroma and nutrient properties, and it has a major economic value for high producing countries. However, characterization of its techno-functional properties and in-depth understanding of oxidative stability is needed to produce food of high quality and stability. Thus, this work focused on the chemical, functional, thermal, oxidative stability and rheological properties of red pepper powder and paste. Experiment was designed in a Completely Randomized Design (CRD) fashion. The red pepper powder contained 14.50 g/100 g, 44.00 g/100 g and 7.57 g/100 g of crude fat, crude fiber and ash, respectively. The concentration of total phenols, carotenoids and antioxidants activity of the powder were 1.04 g GAE/100 g, 374 mg βc/100 g and 38.61 μmol TE/g, respectively. Functional properties showed lower bulk density (395.1 kg/m3) and higher tapped density (583.4 kg/m3) indicating the higher compressibility of the powder. In contrast, Hausner ratio (1.48), Carr’s index (32%) and angle of repose (45°) indicated poor flowability of the powder. Particle size distribution also indicated that the volume weighted mean values D[4,3] of the powder and paste were 262.20 and 201.46, respectively. Emulsifying capacity of the powder was 47.5%. Oil and water absorption capacities varied from 1.41 to 1.73 and 0.86 to 2.29 g/g of initial weight, respectively. Higher glass transition temperature was observed for the powder (62.54°C) than the paste (45.64°C). The induction period indicated that red pepper was more stable against oxidation in powder (5.2 h) than in the paste form (3.2 h). Rheological analysis revealed that the paste exhibited shear-thinning behavior. Overall, understanding of the properties of red pepper could contribute to enhance quality.
Den autochthonen Baumarten geht es unter den klimatischen Veränderungen des Klimawandels so- wohl in der freien Landschaft als auch im urbanen Raum zunehmend schlechter (vgl. fIetz & burger 2021; mlV.nrW 2022). Gleichzeitig können in natürlichen Waldökosystemen Anpassungsdynamiken an diese veränderten klimatischen Bedingungen im Rahmen der Laurophyllisierung beobachtet werden, bei dem sich die mitteleuropäischen sommergrünen Laubwälder in teilweise immergrünen Hartlaubwaldgesell- schaften entwickeln (s. frey et al. 2010: 41). Grund hierfür sind die klimatischen Veränderungen bedingt durch den Klimawandel und Gartentrends (s. berger 2008; deHnen-scHmutz et al. 2006). Der Klimawandel scheint daher günstige Bedingungen für wärmebedürftige und frostempfindliche Immergrüne zu bieten, die an die zu erwartenden Klimaten gut angepasst sind (s. WIttIg 2008: 20). Die Immergrünen, durch die der Prozess der Laurophyllisierung maßgeblich beeinflusst wird, haben ihr natürliches Verbreitungsgebiet überwiegend in der subtropischen vollhumiden Klimazone. Das Klimaxstadium dieser Klimate ist ein im- mergrüner Lorbeerwald, der als Zonobiom V zusammengefasst wird (s. brecKle & rafIqPoor 2019).
Auch in deutschen Städten ist eine solche Anpassung der Stadtbäume an sich ändernde klimatische Bedingungen notwendig. Neben dem Klimawandel spielt im urbanen Raum das Stadtklima eine wich- tige Rolle, welches die Standortbedingungen der Pflanzen zusätzlich beeinflusst und die Auswirkungen des Klimawandels verstärkt (s. HennInger & Weber 2020; WeIscHet & endlIcHer 2018; Kuttler 1998). Die vorlie- gende Arbeit soll daher untersuchen, inwiefern sich die Herkünfte der Arten, die am Prozess der Lauro- phyllisierung beteiligt sind, für die Verwendung im städtischen Raum eignen und somit beantworten, inwiefern die Laurophyllisierung eine Chance für die klimaresiliente Gehölzverwendung in der Stadt dar- stellen kann.
Dafür werden die unterschiedlichen Baumstandorte einer Stadt anhand thermischer und hygrischer Verhältnisse zu schematischen Baumstandorttypen zusammengefasst. Während sich durch die ther- mischen Verhältnisse vor allem zentral und dezentral gelegene Baumstandorttypen differenzieren las- sen, trennen die hygrischen Verhältnisse naturnahe Baumstandorttypen von Baumstandorttypen mit eingeschränktem Wurzelraum. Für diese vier Baumstandorttypen wird dann für vier unterschiedliche Städte Deutschlands das zukünftige Mikroklima mithilfe des RCP8.5 in Form eines Klimadiagramms er- mittelt. Durch die differenzierte Auswahl der Untersuchungsgebiete Hamburg, Düsseldorf, München und Berlin können so Aussagen zu regionalen Auswirkungen des Klimawandels getroffen werden. Zudem dienen die Klimadiagramme der unterschiedlichen Baumstandorttypen als Grundlage für den klimati- schen Vergleich mit den Klimaten der Herkünfte der immergrünen Arten des Zonobiom V. Anhand die- ses Vergleiches können Subzonobiome ausfindig gemacht werden, die mehr oder weniger dem Klima der Baumstandorttypen entsprechen. Eines der Subzonobiome, welches eine gute klimatische Referenz darstellt, wird anschließend im Hinblick auf die prägnantesten immergrünen Arten näher betrachtet. Die Auswahl in dieser Arbeit ist auf das sommerregengeprägte Subzonobiom Ost-Asiens gefallen, aus dem insgesamt 20 immergrüne Laubbaumarten, neun Koniferen und eine Palmenart in Form von Steck- briefen näher beschrieben und auf die Eignung für die Verwendung innerhalb der Mirkoklimate der vier Baumstandorttypen eingeschätzt werden.
Iron deficiency is still widespread as a major health problem even in countries with adequate food supply. It mainly affects women but also vegans, vegetarians, and athletes and can lead to various clinical pictures. Biofortification of vitamin C-rich vegetables with iron may be one new approach to face this nutritional challenge. However, so far, little is known about the consumer acceptance of iron-biofortified vegetables, particularly in developed countries. To address this issue, a quantitative survey of 1000 consumers in Germany was conducted. The results showed that depending on the type of vegetable, between 54% and 79% of the respondents were interested in iron-biofortified vegetables. Regression analysis showed a relationship between product acceptance, gender, and area of residence. In addition, relationships were found between consumer preferences for enjoyment, sustainability, and naturalness. Compared to functional food and dietary supplements, 77% of respondents would prefer fresh iron-rich vegetables to improve their iron intake. For a market launch, those iron-rich vegetables appear especially promising, which can additionally be advertised with claims for being rich in vitamin C and cultivated in an environmentally friendly way. Consumers were willing to pay EUR 0.10 to EUR 0.20 more for the iron-biofortified vegetables.