23 research outputs found
Constructive approach to limiting periodic orbits with exponential and power law dynamics
In dynamical systems limit cycles arise as a result of a Hopf bifurcation,
after a control parameter has crossed its critical value. In this study we
present a constructive method to produce dissipative dynamics which lead to
stable periodic orbits as time grows, with predesigned transient dynamics.
Depending on the construction method a) the limiting orbit can be a regular
circle, an ellipse or a more complex closed orbit and b) the approach to the
limiting orbit can follow an exponential law or a power law. This technique
allows to design nonlinear models of dynamical systems with desired
(exponential or power law) relaxation properties.Comment: 17 pages, 6 figure
KoKoN – Ein Expertenwalkthrough zu digitalen Lehr-Kooperationen im Kontext der Nationalen Bildungsplattform
... Für die erfolgreiche Umsetzung digitalgestützter Lehre nehmen sowohl hochschulinterne als auch -übergreifende Kooperationen einen immer höheren ... Stellenwert ein. Die damit einhergehende Vernetzung und das Zusammenwirken verschiedener Bildungsanbieter bilden die Grundlage des lebenslangen Lernens sowie der bildungsbereichübergreifenden Gestaltung von individuellen Bildungsbiografien (vgl. Schleifenbaum, & Walther, 2015). Die Anbahnung und Durchführung von insbesondere digitalen Lehr-Kooperationen erfordern über reine IT-Kenntnisse hinausgehende Kompetenzen seitens der Lehrenden. Für gelingende Kooperationsprozesse zwischen Lehrenden sind daher weitere Facetten digitaler Kompetenz erforderlich, wie bspw. bzgl. der Durchführung von Kommunikationsund Kooperationsprozessen im digitalen Raum, des Aufbaus einer eigenen digitalen Lehr- und Forscher:innen-Identität sowie der Reflexion des eigenen digitalen Lehr-Handelns (Eichhorn, Müller, & Tillmann, 2017; Eichhorn, 2020). [Aus: Herausforderungen für die digitalgestützte Hochschullehre
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Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks
无线传感器网络,作为全球未来十大技术之一,集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术,可实时感知、采集、处理、传输网络分布区域内的各种信息数据,在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议,并针对大规模的无线传感器网络设计了一种树状路由协议,它根据节点地址信息来形成路由,从而简化了复杂繁冗的路由表查找和维护,节省了不必要的开销,提高了路由效率,实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR(AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位:工学硕士院系专业:信息科学与技术学院通信工程系_通信与信息系统学号:2332007115216
Entwicklung und Evaluation digitaler Lernspiele: Wissenschaftliche Befunde jenseits des Entertainment
Ziel des Beitrages ist es, eigene wissenschaftliche Befunde aus vier Jahren Forschung zur Konzeption, Entwicklung und Evaluation digitaler Lernspiele1 für die betriebliche Aus- und Weiterbildung im sozialen Dienstleistungssektor vorzustellen. Die Darstellung der Ergebnisse erfolgt anhand von zwei aktuellen Projekten am Medienzentrum der Technischen Universität Dresden. In beiden Projekten wurden bzw. werden Serious Games für Führungskräfte im sozialen Dienstleistungssektor entwickelt, in welchen der Ansatz des spielerischen Lernens (vgl. Mangold, 2004) zur Vermittlung gesundheitsbezogener Themen herangezogen wird. Methodisch werden die Befunde entlang der Prozessschritte des Learning Experience Design (LXD) (vgl. Ahn, 2018) präsentiert
Entwicklung und Evaluation digitaler Lernspiele: Wissenschaftliche Befunde jenseits des Entertainment
Ziel des Beitrages ist es, eigene wissenschaftliche Befunde aus vier Jahren Forschung zur Konzeption, Entwicklung und Evaluation digitaler Lernspiele1 für die betriebliche Aus- und Weiterbildung im sozialen Dienstleistungssektor vorzustellen. Die Darstellung der Ergebnisse erfolgt anhand von zwei aktuellen Projekten am Medienzentrum der Technischen Universität Dresden. In beiden Projekten wurden bzw. werden Serious Games für Führungskräfte im sozialen Dienstleistungssektor entwickelt, in welchen der Ansatz des spielerischen Lernens (vgl. Mangold, 2004) zur Vermittlung gesundheitsbezogener Themen herangezogen wird. Methodisch werden die Befunde entlang der Prozessschritte des Learning Experience Design (LXD) (vgl. Ahn, 2018) präsentiert
Microbial rock inhabitants survive hypervelocity impacts on Mars-like host planets: first phase of lithopanspermia experimentally tested
The scenario of lithopanspermia describes the viable transport of microorganisms via meteorites. To test the first step of lithopanspermia, i.e., the impact ejection from a planet, systematic shock recovery experiments within a pressure range observed in martian meteorites (5–50 GPa) were performed with dry layers of microorganisms (spores of Bacillus subtilis, cells of the endolithic cyanobacterium Chroococcidiopsis, and thalli and ascocarps of the lichen Xanthoria elegans) sandwiched between gabbro discs (martian analogue rock). Actual shock pressures were determined by refractive index measurements and Raman spectroscopy, and shock temperature profiles were calculated. Pressure-effect curves were constructed for survival of B. subtilis spores and Chroococcidiopsis cells from the number of colony-forming units, and for vitality of the photobiont and mycobiont of Xanthoria elegans from confocal laser scanning microscopy after live/dead staining (FUN-I). A vital launch window for the transport of rock-colonizing microorganisms from a Mars-like planet was inferred, which encompasses shock pressures in the range of 5 to about 40 GPa for the bacterial endospores and the lichens, and a more limited shock pressure range for the cyanobacterium (from 5–10 GPa). The results support concepts of viable impact ejections from Mars-like planets and the possibility of reseeding early Earth after asteroid cataclysms
Magnetic Nanoparticle Based Nonviral MicroRNA Delivery into Freshly Isolated CD105 +
Genetic modifications of bone marrow derived human mesenchymal stem cells (hMSCs) using microRNAs (miRs) may be used to improve their therapeutic potential and enable innovative strategies in tissue regeneration. However, most of the studies use cultured hMSCs, although these can lose their stem cell characteristics during expansion. Therefore, we aimed to develop a nonviral miR carrier based on polyethylenimine (PEI) bound to magnetic nanoparticles (MNPs) for efficient miR delivery in freshly isolated hMSCs. MNP based transfection is preferable for genetic modifications in vivo due to improved selectivity, safety of delivery, and reduced side effects. Thus, in this study different miR/PEI and miR/PEI/MNP complex formulations were tested in vitro for uptake efficiency and cytotoxicity with respect to the influence of an external magnetic field. Afterwards, optimized magnetic complexes were selected and compared to commercially available magnetic vectors (Magnetofectamine, CombiMag). We found that all tested transfection reagents had high miR uptake rates (yielded over 60%) and no significant cytotoxic effects. Our work may become crucial for virus-free introduction of therapeutic miRs as well as other nucleic acids in vivo. Moreover, in the field of targeted stem cell therapy nucleic acid delivery prior to transplantation may allowfor initial cell modulation in vitro
Magnetic Nanoparticle Based Nonviral MicroRNA Delivery into Freshly Isolated CD105+ hMSCs
Genetic modifications of bone marrow derived human mesenchymal stem cells (hMSCs) using microRNAs (miRs) may be used to improve their therapeutic potential and enable innovative strategies in tissue regeneration. However, most of the studies use cultured hMSCs, although these can lose their stem cell characteristics during expansion. Therefore, we aimed to develop a nonviral miR carrier based on polyethylenimine (PEI) bound to magnetic nanoparticles (MNPs) for efficient miR delivery in freshly isolated hMSCs. MNP based transfection is preferable for genetic modifications in vivo due to improved selectivity, safety of delivery, and reduced side effects. Thus, in this study different miR/PEI and miR/PEI/MNP complex formulations were tested in vitro for uptake efficiency and cytotoxicity with respect to the influence of an external magnetic field. Afterwards, optimized magnetic complexes were selected and compared to commercially available magnetic vectors (Magnetofectamine, CombiMag). We found that all tested transfection reagents had high miR uptake rates (yielded over 60%) and no significant cytotoxic effects. Our work may become crucial for virus-free introduction of therapeutic miRs as well as other nucleic acids in vivo. Moreover, in the field of targeted stem cell therapy nucleic acid delivery prior to transplantation may allowfor initial cell modulation in vitro