Search

The aim of this work is to introduce the Calculus of Variations, showing some of its fundamental methods and techniques. In the first part, our focus will be on regular solutions, and we will study the classical methods that lead to the Euler-Lagrange equations as optimality conditions. We will examine different formulations of these equations, particularly the Hamiltonian formulation, which is connected to the Hamilton-Jacobi system of partial differential equations. By utilizing field theories, we will establish conditions under which the Euler-Lagrange equations are not only necessary but also sufficient conditions. In the second part, we will proof some existence results for weak solutions in Sobolev spaces and provide a brief overview of the vectorial case of these problems and the relaxation theory. Finally we will see some regularity results which will guarantee that solutions which in principle are weak actually are regular solutions., Esta memoria pretende ser una introducci´on al C´alculo de Variaciones, mostrando algunos de sus m´etodos y t´ecnicas fundamentales. En su primera parte nos interesamos por soluciones regulares a los problemas planteados, y mostramos m´etodos cl´asicos que conducen a las condiciones de optimalidad conocidas como ecuaciones de Euler-Lagrange. Damos varias formulaciones de dichas condiciones, en particular la formulaci´on Hamiltoniana (o ecuaciones can´onicas de Euler-Lagrange), cuyas soluciones est´an relacionadas con el sistema de ecuaciones en derivadas parciales de Hamilton-Jacobi. Mediante la Teor´ıa de Campos proporcionamos condiciones que hacen que las ecuaciones de Euler-Lagrange no s´olo sean condiciones necesarias sino tambi´en suficientes de optimalidad. En la segunda parte probamos resultados de existencia de soluci´on d´ebil en los espacios de Sobolev, y hacemos una breve incursi´on en los problemas vectoriales y en la teor´ıa de la relajaci´on. Finalmente, vemos resultados de regularidad que permiten asegurar que soluciones, que en principio son s´olo d´ebiles, son en realidad fuertes (regulares).

Item does not contain fulltext

BioTinkering als Making-Aktivität in der Biologie begeistert Schüler:innen für die Pflanzenwelt und kann den naturwissenschaftlichen Unterricht durch überfachliche, digitale, prozessbasierte und produktorientierte Projektarbeiten bereichern. Dieser Artikel stellt Making-Aktivitäten im Themenbereich Pflanzenbiologie vor und diskutiert deren Kompetenzorientierung im Rahmen des Schweizerischen Lehrplan 21. Da sich BioTinkering anhand verschiedener Bereiche konstituiert, kann damit eine Vielzahl von Kompetenzen geschult werden. Im Artikel werden zur Vermeidung von Missverständnissen aufgrund der Multidisziplinarität eingangs Begriffsklärungen gegeben. Darauf folgend stellen wir Vorteile und Herausforderungen in Form von drei Thesen vor. Diese beinhalten (1) den Bezug von BioTinkering zum traditionellen naturwissenschaftlichen Unterricht, (2) die Thematisierung der Komplexität und des Zeitbedarfs sowie (3) die Förderung überfachlicher Kompetenzen. Im Anschluss diskutieren wir die Entwicklung und Erprobung von BioTinkering-Aktivitäten durch das CreativeLabZ des Zürich-Basel Plant Science Centers und stellen einen Leitfaden zur Anleitung von BioTinkering-Aktivitäten vor. Die Evaluationsresultate zeigen, dass BioTinkering sowohl für Lehrpersonen als auch für Schüler:innen interessant und kompetenzerweiternd ist., BioTinkering as a biology topic for making activities gets students excited about the world of plants and contributes to science education by including interdisciplinarity, digital tools, process-based and product-oriented project work. This article presents making activities related to plant biology and discusses their relation to competences of the Swiss school curriculum Lehrplan 21. BioTinkering, being constituted from multiple disciplines, can develop and train a plethora of competences. Since the term and practice of BioTinkering is constituted from various subject areas, the used terminology is explained at the beginning of the article to avoid misunderstandings. Additionally, we present advantages and challenges in the form of three theses. These include (1) how BioTinkering relates to traditional science education, (2) addressing complexity and time requirements, and (3) the approach towards the development of cross curricular competencies. Subsequently, we discuss the BioTinkering activities and facilitator guide provided by the CreativeLabZ of the Zurich-Basel Plant Science Center. The evaluation results show that BioTinkering is interesting and enriching for both teachers and pupils.

Today's security solutions for IoT applications remain static in an ever-changing environment, making applications insecure and vulnerable to ever-growing cyber threats. The static solutions make credential life-cycle management difficult and lack proper protection of APIs. Overall, they weaken the security of not only the IoT devices but all components involved. A more dynamic approach to the security of IoT applications is required. IoThentix has developed a token-based approach to device authentication that not only allows IoT devices to access protected APIs according to state-of-the-art standards but also enables dynamic management of device credentials. As a result, it significantly improves the credential life-cycle management and the security of the entire IoT application.

Abandoned, lost, or discarded fishing gear (ALDFG), represents a significant percentage of the global plastic pollution, currently considered one of the major sources from sea-based activities. However, there is still limited understanding of the quantities of ALDFG present on the seafloor and their impacts. In this study, data on the presence of ALDFG was obtained from a large archive of seafloor video footage (351 dives) collected by different imaging platforms in the Azores region over 15 years (2006-2020). Most ALDFG items observed in the images relate to the local bottom longline fishery operating in the region, and include longlines but also anchors, weights, cables and buoys. A generalized additive mixed model (GAMM) was used to predict the distribution and abundance of ALDFG over the seafloor within the limits of the Azores Exclusive Economic Zone (EEZ) using a suite of environmental and anthropogenic variables. We estimated an average of 113 ± 310 items km-2 (597 ± 756 per km-2 above 1000 m depth), which could imply that over 20 million ALDFG items are present on the deep seafloor of the Azores EEZ. The resulting model identified potential hotspots of ALDFG along the seabed, some of them located over sensitive benthic habitats, such as specific seamounts. In addition, the interactions between ALDFG and benthic organisms were also analysed. Numerous entanglements were observed with several species of large anthozoans and sponges. The use of predictive distribution modelling for ALDFG should be regarded as a useful tool to support ecosystem-based management, which can provide indirect information about fishing pressure and allow the identification of potential high-risk areas. Additional knowledge about the sources, amounts, fates and impacts of ALDFG will be key to address the global issue of plastic pollution and the effects of fishing on marine ecosystems.

Real estate is at the confluence of several major transformations: higher inflation, higher interest rates, and increasing ESG risks. In this Roundup, experts from academia, industry, and regulation discuss how investors and households navigate new difficult tradeoffs in the Swiss context. Will macroeconomic uncertainties affect prices and impact the financial sector? What is the proper place of real estate in an investor's portfolio? Should homeowners rethink their financing options? And will increasingly strict energy regulations impact the market?

Purpose Carbon dioxide (CO$_{2}$) increases cerebral perfusion. The effect of CO$_{2}$ on apnea tolerance, such as after anesthesia induction, is unknown. This study aimed to assess if cerebral apnea tolerance can be improved in obese patients under general anesthesia when comparing O$_{2}$/Air (95%O$_{2}$) to O$_{2}$/CO$_{2}$ (95%O$_{2}$/5%CO$_{2}$). Methods In this single-center, single-blinded, randomized crossover trial, 30 patients 18–65 years, with body mass index > 35 kg/m$^{2}$, requiring general anesthesia for bariatric surgery, underwent two apneas that were preceded by ventilation with either O$_{2}$/Air or O$_{2}$/CO$_{2}$ in random order. After anesthesia induction, intubation, and ventilation with O$_{2}$/Air or O$_{2}$/CO$_{2}$ for 10 min, apnea was performed until the cerebral tissue oxygenation index (TOI) dropped by a relative 20% from baseline (primary endpoint) or oxygen saturation (SpO$_{2}$) reached 80% (safety abortion criterion). The intervention was then repeated with the second substance. Results The safety criterion was reached in all patients before cerebral TOI decreased by 20%. The time until SpO$_{2}$ dropped to 80% was similar in the two groups (+ 6 s with O$_{2}$/CO$_{2}$, 95%CI -7 to 19 s, p = 0.37). Cerebral TOI and PaO$_{2}$ were higher after O$_{2}$/CO$_{2}$ (+ 1.5%; 95%CI: from 0.3 to 2.6; p = 0.02 and + 0.6 kPa; 95%CI: 0.1 to 1.1; p = 0.02). Conclusion O$_{2}$/CO$_{2}$ improves cerebral TOI and PaO$_{2}$ in anesthetized bariatric patients. Better apnea tolerance could not be confirmed.

This article aims to outline the phenomenon of glocalization from the example of the "Ibero-American Collection" published by the International Institute for Intellectual Cooperation from 1930 to 1939. Initially planned to appear in four languages, this collection was eventually published in French only. It is nonetheless an interesting laboratory from which to observe the consequences of the worldwide circulation of literature, through translation, on the uses and definitions of literature, as well as on the simultaneous production of the global and the local. In this, it is exemplary of a particular moment in the history of the idea of world literature.