Multiple Repräsentationen als fachdidaktischer Zugang zum Satz von Gauß - Qualitative Zugänge zur Interpretation der Divergenz von Vektorfeldern

Die Divergenz ist ein zentrales Konzept der Vektoranalysis und relevant für viele Teilgebiete der Physik, in denen Vektorfelder z. B. zur Beschreibung von Bewegungen verwendet werden. Für die physikalische Anwendung ist dabei vor allem ein konzeptionelles Verständnis der Divergenz von Bedeutung, welches Studierenden jedoch im Gegensatz zu algebraischen Berechnungen häufig Schwierigkeiten bereitet. Bisherige Forschungsergebnisse betonen daher die Notwendigkeit zur Förderung des konzeptionellen Verständnisses u. a. durch den Einsatz multi-repräsentationaler, qualitativer Zugänge. Zu diesem Zweck stellt dieser Beitrag einen visuellen Zugang zum qualitativen Verständnis der Divergenz vor, der auf einer Beurteilung der partiellen Vektorableitungen anhand zweidimensionaler Vektorfelddiagramme beruht. Da insbesondere die Zerlegung von Vektoren in ihre Feldkomponenten - eine zur Beurteilung der partiellen Ableitungen essentielle Prozedur - eine Herausforderung für Studierende darstellt, werden zudem Anregungen für eine instruktionale Unterstützung durch Zeichenaktivitäten gegeben. Abschließend wird eine Studie zur Wirksamkeitsuntersuchung einer zeichenbasierten Instruktion vorgestellt.

Multiple Repräsentationen als fachdidaktischer Zugang zum Satz von Gauß - Qualitative Zugänge zur Interpretation der Divergenz von Vektorfeldern

Die Divergenz ist ein zentrales Konzept der Vektoranalysis und relevant für viele Teilgebiete der Physik, in denen Vektorfelder z. B. zur Beschreibung von Bewegungen verwendet werden. Für die physikalische Anwendung ist dabei vor allem ein konzeptionelles Verständnis der Divergenz von Bedeutung, welches Studierenden jedoch im Gegensatz zu algebraischen Berechnungen häufig Schwierigkeiten bereitet. Bisherige Forschungsergebnisse betonen daher die Notwendigkeit zur Förderung des konzeptionellen Verständnisses u. a. durch den Einsatz multi-repräsentationaler, qualitativer Zugänge. Zu diesem Zweck stellt dieser Beitrag einen visuellen Zugang zum qualitativen Verständnis der Divergenz vor, der auf einer Beurteilung der partiellen Vektorableitungen anhand zweidimensionaler Vektorfelddiagramme beruht. Da insbesondere die Zerlegung von Vektoren in ihre Feldkomponenten - eine zur Beurteilung der partiellen Ableitungen essentielle Prozedur - eine Herausforderung für Studierende darstellt, werden zudem Anregungen für eine instruktionale Unterstützung durch Zeichenaktivitäten gegeben. Abschließend wird eine Studie zur Wirksamkeitsuntersuchung einer zeichenbasierten Instruktion vorgestellt.

The impact of multiple representations on students' understanding of vector field concepts: Implementation of simulations and sketching activities into lecture-based recitations in undergraduate physics

Multiple external representations (e.g., diagrams, equations) and their interpretations play a central role in science and science learning as research has shown that they can substantially facilitate the learning and understanding of science concepts. Therefore, multiple and particularly visual representations are a core element of university physics. In electrodynamics, which students encounter already at the beginning of their studies, vector fields are a central representation typically used in two forms: the algebraic representation as a formula and the visual representation depicted by a vector field diagram. While the former is valuable for quantitative calculations, vector field diagrams are beneficial for showing many properties of a field at a glance. However, benefiting from the mutual complementarity of both representations requires representational competencies aiming at referring different representations to each other. Yet, previous study results revealed several student problems particularly regarding the conceptual understanding of vector calculus concepts. Against this background, we have developed research-based, multi-representational learning tasks that focus on the visual interpretation of vector field diagrams aiming at enhancing a broad, mathematical as well as conceptual, understanding of vector calculus concepts. Following current trends in education research and considering cognitive psychology, the tasks incorporate sketching activities and interactive (computer-based) simulations to enhance multi-representational learning. In this article, we assess the impact of the learning tasks in a field study by implementing them into lecture-based recitations in a first-year electrodynamics course at the University of Göttingen. For this, a within- and between-subjects design is used comparing a multi-representational intervention group and a control group working on traditional calculation-based tasks. To analyze the impact of multiple representations, students' performance in a vector calculus test as well as their perceived cognitive load during task processing is compared between the groups. Moreover, analyses offer guidance for further design of multi-representational learning tasks in field-related physics topics

Coordinating vector field equations and diagrams with a serious game in introductory physics

Mathematical reasoning with algebraic and graphical representations is essential for success in physics courses. Many problems require students to fluently move between algebraic and graphical representations. We developed a freely available serious game to challenge the representational fluency of introductory students regarding vector fields. Within the game, interactive puzzles are solved using different types of vector fields that must be configured with the correct mathematical parameters. A reward system implemented in the game prevents from using trial-and-error approaches and instead encourages the player to establish a mental connection between the graphical representation of the vector field and the (algebraic) equation before taking any action. For correct solutions, the player receives points and can unlock further levels. We report about the aim of the game from an educational perspective, describe potential learning scenarios and reflect about a first attempt to use the game in the classroom

A CONSCIÊNCIA ECOLÓGICA E AS ATITUDES DE CONSUMO DE STATUS

A recurrent issue is the absence of relationship between ecological awareness and luxury consumption. In this perspective, this study aims to analyze the ecological awareness and propensity to luxury consumption. The research started from a quantitative and descriptive approach, operationalized by a survey with 253 Internet users in the states of Santa Catarina and Rio Grande do Sul - Brazil. Results show that subjects, in general, have a high degree of environmental awareness, showing up, however, somewhat likely to use status. It is inferred that both behaviors are not complementary, and the greater ecological awareness lower propensity to luxury consume.Uma questão recorrente nos estudos que tentam identificar o perfil do consumidor é a ausência de relação entre consciência ecológica e o comportamento de consumo de status. Nesta perspectiva, este estudo visa analisar a consciência ecológica e a propensão ao consumo de status. A pesquisa partiu de uma abordagem quantitativa e descritiva, operacionalizada por meio de uma survey com 253 internautas dos Estados de Santa Catarina e do Rio Grande do Sul. Os resultados mostram que os entrevistados, de uma forma geral, têm alto grau de consciência ecológica, mostrando-se, contudo, pouco propensos ao consumo de status. Infere-se, a partir do pressuposto do trabalho, que ambos comportamentos não são complementares, sendo que quanto maior a consciência ecológica do indivíduo menor a sua propensão ao consumo de status

The role of Nrf1 and Nrf2 in the regulation of glutathione and redox dynamics in the developing zebrafish embryo

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Redox Biology 13 (2017): 207–218, doi:10.1016/j.redox.2017.05.023.Redox signaling is important for embryogenesis, guiding pathways that govern processes crucial for embryo patterning, including cell polarization, proliferation, and apoptosis. Exposure to pro-oxidants during this period can be deleterious, resulting in altered physiology, teratogenesis, later-life diseases, or lethality. We previously reported that the glutathione antioxidant defense system becomes increasingly robust, including a doubling of total glutathione and dynamic shifts in the glutathione redox potential at specific stages during embryonic development in the zebrafish, Danio rerio. However, the mechanisms underlying these changes are unclear, as is the effectiveness of the glutathione system in ameliorating oxidative insults to the embryo at different stages. Here, we examine how the glutathione system responds to the model pro-oxidants tert-butylhydroperoxide and tert-butylhydroquinone at different developmental stages, and the role of Nuclear factor erythroid 2-related factor (Nrf) proteins in regulating developmental glutathione redox status. Embryos became increasingly sensitive to pro-oxidants after 72 h post-fertilization (hpf), after which the duration of the recovery period for the glutathione redox potential was increased. To determine whether the doubling of glutathione or the dynamic changes in glutathione redox potential are mediated by zebrafish paralogs of Nrf transcription factors, morpholino oligonucleotides were used to knock down translation of Nrf1 and Nrf2 (nrf1a, nrf1b, nrf2a, nrf2b). Knockdown of Nrf1a or Nrf1b perturbed glutathione redox state until 72 hpf. Knockdown of Nrf2 paralogs also perturbed glutathione redox state but did not significantly affect the response of glutathione to pro-oxidants. Nrf1b morphants had decreased gene expression of glutathione synthesis enzymes, while hsp70 increased in Nrf2b morphants. This work demonstrates that despite having a more robust glutathione system, embryos become more sensitive to oxidative stress later in development, and that neither Nrf1 nor Nrf2 alone appear to be essential for the response and recovery of glutathione to oxidative insults.This research was supported by several NIH grants, including F32ES028085 (to KES), F32ES017585 (to ART-L), F32ES019832 (to LMW), P20GM103423 (to LMW), R01ES025748 (to ART-L), R01ES015912 (JJS), and R01ES016366 (MEH). Additional research support was provided by the J. Seward Johnson Fund at WHOI and the WHOI Postdoctoral Scholar Award with funding from Walter A. and Hope Noyes Smith (to ART-L)

Levantamento bibliométrico de fungos nematófagos no controle dos nematoides das galhas

Os nematoides das galhas (Meloidogyne spp.) estão distribuídos por diversos países do mundo parasitando plantas de interesse econômico. Vários estudos foram realizados com espécies de fungos nematófagos para o controle desses patógenos, e um levantamento bibliométrico possibilitará conhecer: i) os principais países que mais publicaram estudos com fungos nematófagos para o controle de Meloidogyne spp.; ii) o aspecto temporal das publicações e das descobertas de novas espécies de fungos nematófagos; iii) as principais espécies de fungos nematófagos; iv) as espécies de Meloidogyne spp. foco das pesquisas; v) as condições de realização das pesquisas e vi) as principais plantas hospedeiras de Meloidogyne spp. estudadas. O levantamento apontou a Índia como o país que mais publicou entre os anos de 1976 e 2017, seguida pelo Brasil. A frequência das publicações apresentou picos na década de 1990 e pós o ano 2000. Das 185 espécies de fungos nematófagos estudadas, a espécie mais frequente foi Pochonia chlamydosporia. Os fungos nematófagos tiveram como alvo 9 espécies de Meloidogyne, sendo M. incognita e M. javanica as mais estudadas no mundo e no Brasil, respectivamente. Em 71,0% e 89,5% das ocorrências internacionais e brasileiras, respectivamente, foram realizados experimentos em condição in vivo, no qual Solanum lycopersicum foi o hospedeiro mais estudado. Muitos avanços ocorreram nos últimos 30 anos no controle biológico de nematoides por fungos nematófagos

Eddy Study to Understand Physical-Chemical-Biological Coupling and the Biological Carbon Pump as a Function of Eddy Type off West Africa, Cruise No. M160, 23.11.2019 - 20.12.2019, Mindelo (Cabo Verde) - Mindelo (Cabo Verde)

Cruise M160 is part of concerted MOSES/REEBUS Eddy Study featuring three major research expeditions (M156, M160, MSM104). It aims to develop both a qualitative and quantitative understanding of the role of physical-chemical-biological coupling in eddies for the biological pump. The study is part of the MOSES “Ocean Eddies” event chain, which follows three major hypotheses to be addressed by the MOSES/REEBUS field campaigns: (1) Mesoscale and sub-mesoscale eddies play an important role in transferring energy along the energy cascade from the large-scale circulation to dissipation at the molecular level. (2) Mesoscale and sub-mesoscale eddies are important drivers in determining onset, magnitude and characteristics of biological productivity in the ocean and contribute significantly to global primary production and particle export and transfer to the deep ocean. (3) Mesoscale and sub-mesoscale eddies are important for shaping extreme biogeochemical environments (e.g., pH, oxygen) in the oceans, thus acting as a source/sink function for greenhouse gases. In contrast to the other two legs, MOSES Eddy Study II during M160 did not include any benthic work but focused entirely on the pelagic dynamics within eddies. It accomplished a multi-disciplinary, multi-parameter and multi-platform study of two discrete cyclonic eddies in an unprecedented complexity. The pre-cruise search for discrete eddies suitable for detailed study during M160 had already started a few months prior to the cruise. Remote sensing data products (sea surface height, sea surface temperature, ocean color/chlorophyll a) were used in combination with eddy detection algorithms and numerical modelling to identify and track eddies in the entire eddy field off West Africa. In addition, 2 gliders and 1 waveglider had been set out from Mindelo/Cabo Verde for pre-cruise mapping of the potential working area north of the Cabo Verdean archipelago. At the start of M160, a few suitable eddies – mostly of cyclonic type – had been identified, some of which were outside the safe operation range of the motorglider plane. As technical problems delayed the flight operations, the first eddy (center at 14.5°N/25°W) for detailed study was chosen to the southwest of the island of Fogo. It was decided to carry out a first hydrographic survey there followed by the deployment of a suite of instruments (gliders, waveglider, floats, drifter short-term mooring). Such instrumented, we left this first eddy and transited – via a strong anticyclonic feature southwest of the island of Santiago – to the region northeast of the island of Sal, i.e. in the working range of the glider plane. During the transit, a full suite of underway measurements as well as CTD/RO section along 22°W (16°-18.5°N) were carried in search for sub-surface expressions of anticyclonic eddy features. In the northeast, we had identified the second strong cyclonic eddy (center at 18°N/22.5°W) which was chosen for detailed study starting with a complete hydrographic survey (ADCP, CTD/RO, other routine station work). After completion of the mesoscale work program, we identified a strong frontal region at the southwestern rim of the cyclonic eddy, which was chosen for the first sub-mesoscale study with aerial observation component. There, the first dye release experiment was carried out which consisted of the dye release itself followed by an intense multi-platforms study of the vertical and horizontal spreading of the initial dye streak. This work was METEOR-Berichte, Cruise M160, Mindelo – Mindelo, 23.11.2019 4 – 20.12.2019 supported and partly guided by aerial observation of the research motorglider Stemme, which was still somewhat compromised by technical issues and meteorological conditions (high cloud cover, Saharan dust event). Nevertheless, this first dye release experiment was successful and showed rapid movement of the dynamic meandering front. After completion of work on this second eddy and execution of a focused sampling program at the Cape Verde Ocean Observation, RV METEOR returned to the first eddy for continuation of the work started there in the beginning of the cruise. This was accompanied by a relocation of the airbase of Stemme from the international airport of Sal to the domestic airport of Fogo. The further execution of the eddy study at this first eddy, which again included a complete hydrographic survey followed by a mesoscale eddy study with dye release, was therefore possible with aerial observations providing important guidance for work on RV METEOR. Overall, M160 accomplished an extremely intense and complex work program with 212 instrument deployments during station work, 137 h of observation with towed instruments and a wide range of underway measurements throughout the cruise. Up to about 30 individually tracked platforms (Seadrones, glider, wavegliders, drifters, floats) were in the water at the same time providing unprecedented and orchestrated observation capabilities in an eddy. All planned work components were achieved and all working groups acquired the expected numbers of instrument deployments and sampling opportunities