Quantification of the effects of architectural traits on dry mass production and light interception of tomato canopy under different temperature regimes using a dynamic functional-structural plant model

There is increasing interest in evaluating the environmental effects on crop architectural traits and yield improvement. However, crop models describing the dynamic changes in canopy structure with environmental conditions and the complex interactions between canopy structure, light interception, and dry mass production are only gradually emerging. Using tomato (Solanum lycopersicum L.) as a model crop, a dynamic functional-structural plant model (FSPM) was constructed, parameterized, and evaluated to analyse the effects of temperature on architectural traits, which strongly influence canopy light interception and shoot dry mass. The FSPM predicted the organ growth, organ size, and shoot dry mass over time with high accuracy (>85%). Analyses of this FSPM showed that, in comparison with the reference canopy, shoot dry mass may be affected by leaf angle by as much as 20%, leaf curvature by up to 7%, the leaf length: width ratio by up to 5%, internode length by up to 9%, and curvature ratios and leaf arrangement by up to 6%. Tomato canopies at low temperature had higher canopy density and were more clumped due to higher leaf area and shorter internodes. Interestingly, dry mass production and light interception of the clumped canopy were more sensitive to changes in architectural traits. The complex interactions between architectural traits, canopy light interception, dry mass production, and environmental conditions can be studied by the dynamic FSPM, which may serve as a tool for designing a canopy structure which is 'ideal' in a given environment.

Plutonium release from Fukushima Daiichi fosters the need for more detailed investigations

The contamination of Japan after the Fukushima accident has been investigated mainly for volatile fission products, but only sparsely for actinides such as plutonium. Only small releases of actinides were estimated in Fukushima. Plutonium is still omnipresent in the environment from previous atmospheric nuclear weapons tests. We investigated soil and plants sampled at different hot spots in Japan, searching for reactor-borne plutonium using its isotopic ratio Pu-240/Pu-239. By using accelerator mass spectrometry, we clearly demonstrated the release of Pu from the Fukushima Daiichi power plant: While most samples contained only the radionuclide signature of fallout plutonium, there is at least one vegetation sample whose isotope ratio (0.381 +/- 0.046) evidences that the Pu originates from a nuclear reactor (Pu239+240 activity concentration 0.49 Bq/kg). Plutonium content and isotope ratios differ considerably even for very close sampling locations, e.g. the soil and the plants growing on it. This strong localization indicates a particulate Pu release, which is of high radiological risk if incorporated.

Hatties Transparenztraum: Freie Sicht auf das Lehren und Lernen

Das Wort Transparenz ist aus den aktuellen, öffentlichen Debatten um Informationsfreiheit nicht mehr wegzudenken. Doch wer den Transparenzdiskurs ausschließlich auf politischer Ebene im Kontext von Whistleblowern, Wikileaks, NSA-Affäre oder Piraten-Partei verortet, verkennt, dass Transparenz, wie Han feststellt, als ein systematischer Zwang wirkt, der alle gesellschaftlichen Bereiche – also auch das Bildungswesen – erfasst und sie tiefgreifend verändert. [...] Die Hattie-Studie markiert hier einen besonderen Höhepunkt, da sie alle bisher veröffentlichten Studien an Umfang und Aufwand deutlich übertrifft und dabei den Anspruch erhebt, Lernen und Lehren sichtbar zu machen. Doch welches Recht hat der Sehende auf das Sichtbar-zu-Machende? Wer profitiert hier? Unter welchen Bedingungen kann der oder die Durch-Schaute diese Veräußerung des Selbst verweigern, d.h. seine bzw. ihre Undurchschaubarkeit geltend machen? Welche anthropologischen und gesellschaftlichen Konsequenzen folgen aus dem Anspruch, den Menschen durchschaubar zu machen? Und dürfen bzw. können wir die Preisgabe von Geheimnissen bedenkenlos fordern? Bevor diese Fragen rund um die Hattie-Studie erörtert werden, sei zum Zwecke eines tieferen Verständnisses zunächst nach der Herkunft dieses Transparenztraums und des damit verbundenen Strebens nach Durch-Sichtigkeit von Mensch und Gesellschaft gefragt. (DIPF/Orig.)

AUXIN-BINDING-PROTEIN1 (ABP1) in phytochrome-B-controlled responses

The auxin receptor ABP1 directly regulates plasma membrane activities including the number of PIN-formed (PIN) proteins and auxin efflux transport. Red light (R) mediated by phytochromes regulates the steady-state level of ABP1 and auxin-inducible growth capacity in etiolated tissues but, until now, there has been no genetic proof that ABP1 and phytochrome regulation of elongation share a common mechanism for organ elongation. In far red (FR)-enriched light, hypocotyl lengths were larger in the abp1-5 and abp1/ABP1 mutants, but not in tir1-1, a null mutant of the TRANSPORT-INHIBITOR-RESPONSE1 auxin receptor. The polar auxin transport inhibitor naphthylphthalamic acid (NPA) decreased elongation in the low R: FR light-enriched white light (WL) condition more strongly than in the high red: FR light-enriched condition WL suggesting that auxin transport is an important condition for FR-induced elongation. The addition of NPA to hypocotyls grown in R-and FR-enriched light inhibited hypocotyl gravitropism to a greater extent in both abp1 mutants and in phyB-9 and phyA-211 than the wild-type hypocotyl, arguing for decreased phytochrome action in conjunction with auxin transport in abp1 mutants. Transcription of FR-enriched light-induced genes, including several genes regulated by auxin and shade, was reduced 3-5-fold in abp1-5 compared with Col and was very low in abp1/ABP1. In the phyB-9 mutant the expression of these reporter genes was 5-15-fold lower than in Col. In tir1-1 and the phyA-211 mutants shade-induced gene expression was greatly attenuated. Thus, ABP1 directly or indirectly participates in auxin and light signalling.

Influence of Cobalt on the Properties of Load-Sensitive Magnesium Alloys

In this study, magnesium is alloyed with varying amounts of the ferromagnetic alloying element cobalt in order to obtain lightweight load-sensitive materials with sensory properties which allow an online-monitoring of mechanical forces applied to components made from Mg-Co alloys. An optimized casting process with the use of extruded Mg-Co powder rods is utilized which enables the production of magnetic magnesium alloys with a reproducible Co concentration. The efficiency of the casting process is confirmed by SEM analyses. Microstructures and Co-rich precipitations of various Mg-Co alloys are investigated by means of EDS and XRD analyses. The Mg-Co alloys' mechanical strengths are determined by tensile tests. Magnetic properties of the Mg-Co sensor alloys depending on the cobalt content and the acting mechanical load are measured utilizing the harmonic analysis of eddy-current signals. Within the scope of this work, the influence of the element cobalt on magnesium is investigated in detail and an optimal cobalt concentration is defined based on the performed examinations.

Absorption Measurements of Periodically Poled Potassium Titanyl Phosphate (PPKTP) at 775 nm and 1550 nm

The efficient generation of second-harmonic light and squeezed light requires non-linear crystals that have low absorption at the fundamental and harmonic wavelengths. In this work the photo-thermal self-phase modulation technique is exploited to measure the absorption coefficient of periodically poled potassium titanyl phosphate (PPKTP) at 1,550 nm and 775 nm. The measurement results are (84 +/- 40) ppm/cm and (127 +/- 24) ppm/cm, respectively. We conclude that the performance of state-of-the-art frequency doubling and squeezed light generation in PPKTP is not limited by absorption.

"Warum darf die mit Laptop spielen und wir nicht?". Eine Fallanalyse zur beruflichen Initiation und Kooperation von Lehramtsstudierenden im Schulpraktikum

Mit den Reformen der Lehrerbildung war seit Anfang des 21. Jahrhunderts die Umsetzung eines stärkeren Berufsfeldbezugs im Lehramtsstudium verbunden. Niederschlag fand dies u.a. in einer Ausweitung von Schulpraktika in den Studiengängen in Deutschland. Erste Erfahrungen in der praktischen schulpädagogischen Arbeit sollten dabei möglich werden und an der Hochschule erworbenes wissenschaftliches Wissen und Können einen ersten reflexiven Anwendungsbezug erhalten. [...] In explorativer Absicht wird vor diesem Hintergrund im Folgenden eine Protokollsequenz untersucht, in der eine Lehrerin, eine Praktikantin und Schüler in einer Unterrichtsstunde interagieren. Bestimmend für die Auswahl war die Tatsache, dass hier die Praktikantin an der Disziplinierung der Schüler beteiligt wird - was nach langjähriger Erfahrung des Autors nicht selten vorkommt. (DIPF/Orig.)

Characterization of nanoparticle mediated laser transfection by femtosecond laser pulses for applications in molecular medicine

Background: In molecular medicine, the manipulation of cells is prerequisite to evaluate genes as therapeutic targets or to transfect cells to develop cell therapeutic strategies. To achieve these purposes it is essential that given transfection techniques are capable of handling high cell numbers in reasonable time spans. To fulfill this demand, an alternative nanoparticle mediated laser transfection method is presented herein. The fs-laser excitation of cell-adhered gold nanoparticles evokes localized membrane permeabilization and enables an inflow of extracellular molecules into cells. Results: The parameters for an efficient and gentle cell manipulation are evaluated in detail. Efficiencies of 90% with a cell viability of 93% were achieved for siRNA transfection. The proof for a molecular medical approach is demonstrated by highly efficient knock down of the oncogene HMGA2 in a rapidly proliferating prostate carcinoma in vitro model using siRNA. Additionally, investigations concerning the initial perforation mechanism are conducted. Next to theoretical simulations, the laser induced effects are experimentally investigated by spectrometric and microscopic analysis. The results indicate that near field effects are the initial mechanism of membrane permeabilization. Conclusion: This methodical approach combined with an automated setup, allows a high throughput targeting of several 100,000 cells within seconds, providing an excellent tool for in vitro applications in molecular medicine. NIR fs lasers are characterized by specific advantages when compared to lasers employing longer (ps/ns) pulses in the visible regime. The NIR fs pulses generate low thermal impact while allowing high penetration depths into tissue. Therefore fs lasers could be used for prospective in vivo applications.

Vom Widerspruch des Unterrichtens und Aneignens. Wie in der unterrichtlichen Vermittlung auch die Differenz von Sein und Sollen vermittelt wird

Schulunterricht beansprucht, mit Wolfgang Klafki gesprochen, die „doppelseitige Erschließung“ (Klafki 1959/1967, S. 43): In ihm sollen sich als relevant erachtete Inhalte den Heranwachsenden erschließen und diese sollen zugleich für jene Inhalte erschlossen werden. Nur wenn die Lern- und Bildungsprozesse der SchülerInnen im Unterricht befördert werden, wird er diesem mit ihm gesetzten pädagogischen Anspruch gerecht. Angesichts dessen, dass unterrichtliche Vermittlung vielfach ihr Ziel nicht erreicht, also SchülerInnen nicht das lernen, was ihnen gelehrt wird, stellt sich die Frage, wie die an Unterricht Beteiligten mit dieser Differenz von Sein und Sollen umgehen. Um diese zu beantworten, ist zum einen nachzuvollziehen, wie im Prozess des Unterrichts so gelehrt und gelernt wird, dass einige das zu Lernende lernen und andere dies nicht tun [...], wie also im Unterricht die „Grenze“ zwischen Verstehen und Nicht-Verstehen praktisch gezogen wird. Und zum anderen ist zu erhellen, wie der Widerspruch zwischen Sein und Sollen individuell verarbeitet wird.(DIPF/Orig.)

Proteomic and phosphoproteomic analysis of polyethylene glycol-induced osmotic stress in root tips of common bean (Phaseolus vulgaris L.)

Previous studies have shown that polyethylene glycol (PEG)-induced osmotic stress (OS) reduces cell-wall (CW) porosity and limits aluminium (Al) uptake by root tips of common bean (Phaseolus vulgaris L.). A subsequent transcriptomic study suggested that genes related to CW processes are involved in adjustment to OS. In this study, a proteomic and phosphoproteomic approach was applied to identify OS-induced protein regulation to further improve our understanding of how OS affects Al accumulation. Analysis of total soluble proteins in root tips indicated that, in total, 22 proteins were differentially regulated by OS; these proteins were functionally categorized. Seventy-seven per- cent of the total expressed proteins were involved in metabolic pathways, particularly of carbohydrate and amino acid metabolism. An analysis of the apoplastic proteome revealed that OS reduced the level of five proteins and increased that of seven proteins. Investigation of the total soluble phosphoproteome suggested that dehydrin responded to OS with an enhanced phosphorylation state without a change in abundance. A cellular immunolocalization analysis indicated that dehydrin was localized mainly in the CW. This suggests that dehydrin may play a major protective role in the OS-induced physical breakdown of the CW structure and thus maintenance of the reversibility of CW extensibility during recovery from OS. The proteomic and phosphoproteomic analyses provided novel insights into the complex mechanisms of OS-induced reduction of Al accumulation in the root tips of common bean and highlight a key role for modification of CW structure.

Interessiert euch! Versuch über ein Ethos der Lehramtsstudierenden

Der folgende Text ist die Antwort auf einen Aufruf zur Einreichung von Beiträgen, die sich dem derzeitigen Stand eines Studiums der Germanistik widmen sollten [...]. In diesem Aufruf wird die Frage nach dem „Sinn und Zweck der Germanistik“, wenn diese „weder relevantes Wissen noch relevante Kompetenzen“ vermitteln kann, gestellt. Die Autoren wenden diese Frage in einem Appell nach einem Ethos der Lehramtsstudierenden. Wer die vorgegebenen „relevanten Kompetenzen“ und das vermeintlich „relevante Wissen“ (ebd.) des Lehrplans unhinterfragt aus den bisher in der eigenen Schulzeit gemachten Erfahrungen und dem (Vor-)Gegebenen übernimmt, begeht ihrer Meinung nach einen Fehlschluss, indem er aus dem Sein das Sollen ableitet. (DIPF/Orig.)

Phospholipases and the network of auxin signal transduction with ABP1 and TIR1 as two receptors: a comprehensive and provocative model

Three types of phospholipases, phospholipase D, secreted phospholipase A2, and patatin-related phospholipase A (pPLA) have functions in auxin signal transduction. Potential linkage to auxin receptors ABP1 or TIR1, their rapid activation or post-translational activation mechanisms, and downstream functions regulated by these phospholipases is reviewed and discussed. Only for pPLA all aspects are known at least to some detail. Evidence is gathered that all these signal reactions are located in the cytosol and seem to merge on regulation of PIN-catalyzed auxin efflux transport proteins. As a consequence, auxin concentration in the nucleus is also affected and this regulates the E3 activity of this auxin receptor. We showed that ABP1, PIN2, and pPLA, all outside the nucleus, have an impact on regulation of auxin-induced genes within 30 min. We propose that regulation of PIN protein activities and of auxin efflux transport are the means to coordinate ABP1 and TIR1 activity and that no physical contact between components of the ABP1-triggered cytosolic pathways and TIR1-triggered nuclear pathways of signaling is necessary to perform this.

Digitaler Campus: Vom Medienprojekt zum nachhaltigen Medieneinsatz in der Hochschule

Mit den zunehmend verfügbaren Erkenntnissen aus einer Vielzahl von Projekten und Aktivitäten an Hochschulen geht es heute vorrangig nicht mehr um die Erprobung „neuer“ Ansätze mediengestützten Lernens, sondern um die (Weiter-) Entwicklung von Strukturen und Prozessen, um bestehende Ansätze auf der Basis solcher Erkenntnisse konsequent zu erweitern und die aufgezeigten Potenziale digitaler Medien in der Lehre gezielt zu nutzen. Zentrale Aufgaben werden die Umsetzung von Konzepten des Medieneinsatzes in der alltäglichen Lehre und deren dauerhafte Integration in den Hochschulalltag, in Studienrichtungen und Studiengänge. Dieser Band gibt einen Einblick in aktuelle Bemühungen an Hochschulen, diese Prozesse der Hochschulentwicklung mit und durch Medien zu gestalten. Er beinhaltet die Vorträge der GMW03 – Conference on Media in Higher Education, der 8. Jahrestagung der Gesellschaft für Medien in der Wissenschaft e.V., die vom 16.-19. September 2003 an der Universität Duisburg-Essen stattgefunden hat. (DIPF/Orig.)