TY - JOUR A1 - Unterhuber, Angelika A1 - Povazay, B. A1 - Bizheva, K. A1 - Hermann, B. A1 - Sattmann, Harald A1 - Stingl, A. A1 - Le, Trang A1 - Seefeldt, Michael A1 - Menzel, Ralf A1 - Preusser, Matthias A1 - Budka, Herbert A1 - Schubert, Christian A1 - Reitsamer, H. A1 - Ahnelt, Peter Kurt A1 - Morgan, J. E. T1 - Advances in broad bandwidth light sources for ultrahigh resolution optical coherence tomography N2 - Novel ultra-broad bandwidth light sources enabling unprecedented sub-2 pm axial resolution over the 400 nm-1700 nm wavelength range have been developed and evaluated with respect to their feasibility for clinical ultrahigh resolution optical coherence tomography (UHR OCT) applications. The state-of-the-art light sources described here include a compact Kerr lens mode locked Ti:sapphire laser (lambda(c) = 785 nm, Deltalambda = 260 nm, P-out = 50 mW) and different nonlinear fibre-based light sources with spectral bandwidths (at full width at half maximum) up to 350 nm at lambda(c) = 1130 nm and 470 nm at lambda(c) = 1375 run. In vitro UHR OCT imaging is demonstrated at multiple wavelengths in human cancer cells, animal ganglion cells as well as in neuropathologic and ophthalmic biopsies in order to compare and optimize UHR OCT image contrast, resolution and penetration depth Y1 - 2004 SN - 0031-9155 ER - TY - GEN A1 - Menzel, Ralf A1 - Heuer, Axel A1 - Milonni, Peter W. T1 - Entanglement, complementarity, and vacuum fields in spontaneous parametric down-conversion T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Using two crystals for spontaneous parametric down-conversion in a parallel setup, we observe two-photon interference with high visibility. The high visibility is consistent with complementarity and the absence of which-path information. The observations are explained as the effects of entanglement or equivalently in terms of interfering probability amplitudes and also by the calculation of a second-order field correlation function in the Heisenberg picture. The latter approach brings out explicitly the role of the vacuum fields in the down-conversion at the crystals and in the photon coincidence counting. For comparison, we show that the Hong–Ou–Mandel dip can be explained by the same approach in which the role of the vacuum signal and idler fields, as opposed to entanglement involving vacuum states, is emphasized. We discuss the fundamental limitations of a theory in which these vacuum fields are treated as classical, stochastic fields. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1077 KW - complementarity KW - vacuum fields KW - entanglement KW - Hong-Ou-Mandel effect KW - spontaneous parametric down-conversion Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-473542 SN - 1866-8372 IS - 1077 ER - TY - JOUR A1 - Menzel, Ralf A1 - Heuer, Axel A1 - Milonni, Peter W. T1 - Entanglement, Complementarity, and Vacuum Fields in Spontaneous Parametric Down-Conversion JF - Atoms N2 - Using two crystals for spontaneous parametric down-conversion in a parallel setup, we observe two-photon interference with high visibility. The high visibility is consistent with complementarity and the absence of which-path information. The observations are explained as the effects of entanglement or equivalently in terms of interfering probability amplitudes and also by the calculation of a second-order field correlation function in the Heisenberg picture. The latter approach brings out explicitly the role of the vacuum fields in the down-conversion at the crystals and in the photon coincidence counting. For comparison, we show that the Hong-Ou-Mandel dip can be explained by the same approach in which the role of the vacuum signal and idler fields, as opposed to entanglement involving vacuum states, is emphasized. We discuss the fundamental limitations of a theory in which these vacuum fields are treated as classical, stochastic fields. KW - complementarity KW - vacuum fields KW - entanglement KW - Hong-Ou-Mandel effect KW - spontaneous parametric down-conversion Y1 - 2019 U6 - https://doi.org/10.3390/atoms7010027 SN - 2218-2004 VL - 7 IS - 1 PB - MDPI CY - Basel ER - TY - JOUR A1 - Wöhl-Bruhn, Stefanie A1 - Badar, Muhammad A1 - Bertz, Andreas A1 - Tiersch, Brigitte A1 - Koetz, Joachim A1 - Menzel, Henning A1 - Müller, Peter P. A1 - Bunjes, Heike T1 - Comparison of in vitro and in vivo protein release from hydrogel systems JF - Journal of controlled release N2 - Hydrogel systems based on hydroxyethyl starch-polyethylene glycol methacrylate (HES-P(EG)(6)MA) or hydroxyethyl starch methacrylate (HES-MA) were used to assess the protein release behavior. Here, we analyzed the in vitro release of FITC-anti-human antibodies incorporated in either HES-P(EG)(6)MA or HES-MA hydrogel delivery systems in PBS or human serum. In addition, hydrogel disks and microparticles prepared from the two polymers were subcutaneously implanted in BALB/c mice. The in vivo release of FITC-IgG was non-invasively monitored by an in vivo imaging system (IVIS 200) over a time period of up to 3 months. The imaging system allowed to asses individual animals over time, therefore only a small number of animals was required to obtain high quality data. The reduction in fluorescence intensity at the site of administration was compared to in vitro release profiles. These investigations demonstrated a sustained release from HES-MA hydrogel disks compared to rapidly degrading HES-P(EG)(6)MA disks and microparticles. The sustained release from HES-MA disks could be further optimized by using increased polymer concentrations. Human serum as in vitro release medium reflected better the in vivo release from HES-P(EG)(6)MA systems than PBS, suggesting that the presence of organic substances like proteins or lipids may play a significant role for the release kinetics. KW - In vivo imaging system (IVIS) KW - Hydrogel disks KW - Hydrogel microparticles KW - Release KW - In vivo-in vitro correlation KW - Hydroxyethyl starch (HES) Y1 - 2012 U6 - https://doi.org/10.1016/j.jconrel.2012.05.049 SN - 0168-3659 VL - 162 IS - 1 SP - 127 EP - 133 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Eisenberg, Peter A1 - Menzel, Wolfgang T1 - Grammatik-Werkstatt : Basisartikel Y1 - 1995 ER - TY - GEN A1 - Brendel, Nina A1 - Matzner, Nils A1 - Menzel, Max-Peter T1 - Geographisches Gezwitscher – Analyse von Twitter-Daten als Methode im GW-Unterricht T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Soziale Medien sind ein wesentlicher Bestandteil des Alltags von Schüler*innen und gleichzeitig zunehmend wichtig in Wirtschaft, Politik und Wissenschaft. Am Beispiel von Twitter zeigt dieser Beitrag, dass soziale Medien im Unterricht auch für die Beantwortung geographischer Fragestellungen verwendet werden können. Hierfür eignen sich Twitter-Daten aufgrund ihrer Georeferenzierung und weiterer interessanter Inhalte besonders. Der Beitrag gibt einen Überblick über die Verwendung von Twitter für sozialwissenschaftliche und humangeographische Fragestellungen und reflektiert die Nutzung von Twitter im Unterricht. Für die Unterrichtspraxis werden Beispiele zu den Themen Braunkohle, Flutereignisse und Raumwahrnehmungen sowie Anleitungen zur Auswertung, Anwendung und Reflexion von Twitter-Analysen vorgestellt. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1247 KW - Twitter KW - Soziale Medien KW - Forschungsmethodik KW - Unterrichtsmethoden Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-550614 SN - 1866-8372 SP - 72 EP - 85 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Brendel, Nina A1 - Matzner, Nils A1 - Menzel, Max-Peter T1 - Geographisches Gezwitscher – Analyse von Twitter-Daten als Methode im GW-Unterricht JF - GW-Unterricht N2 - Soziale Medien sind ein wesentlicher Bestandteil des Alltags von Schüler*innen und gleichzeitig zunehmend wichtig in Wirtschaft, Politik und Wissenschaft. Am Beispiel von Twitter zeigt dieser Beitrag, dass soziale Medien im Unterricht auch für die Beantwortung geographischer Fragestellungen verwendet werden können. Hierfür eignen sich Twitter-Daten aufgrund ihrer Georeferenzierung und weiterer interessanter Inhalte besonders. Der Beitrag gibt einen Überblick über die Verwendung von Twitter für sozialwissenschaftliche und humangeographische Fragestellungen und reflektiert die Nutzung von Twitter im Unterricht. Für die Unterrichtspraxis werden Beispiele zu den Themen Braunkohle, Flutereignisse und Raumwahrnehmungen sowie Anleitungen zur Auswertung, Anwendung und Reflexion von Twitter-Analysen vorgestellt. KW - Twitter KW - Soziale Medien KW - Forschungsmethodik KW - Unterrichtsmethoden Y1 - 2021 U6 - https://doi.org/10.1553/gw-unterricht164s72 SN - 2414-4169 SP - 72 EP - 85 PB - Verlag der Österreichischen Akademie der Wissenschaften CY - Wien ER - TY - JOUR A1 - Mishra, Praveen Kumar A1 - Anoop, Ambili A1 - Schettler, Georg A1 - Prasad, Sushma A1 - Jehangir, Arshid A1 - Menzel, Peter A1 - Naumann, Rudolf A1 - Yousuf, A. R. A1 - Basavaiah, Nathani A1 - Deenadayalan, Kannan A1 - Wiesner, Martin G. A1 - Gaye, Birgit T1 - Reconstructed late Quaternary hydrological changes from Lake Tso Moriri, NW Himalaya JF - Quaternary international : the journal of the International Union for Quaternary Research N2 - We present the results of our investigations on the radiocarbon dated core sediments from the Lake Tso Moriri, NW Himalaya aimed at reconstructing palaeohydrological changes in this climatically sensitive region. Based on the detailed geochemical, mineralogical and sedimentological analysis, we recognise several short-term fluctuations superimposed upon seven major palaeohydrological stages identified in this lake since similar to 26 cal ka. Stage I (>20.2 cal ka): shallow lake characterised by input of coarse-grained detrital sediments; Stage II (20.2-16.4 cal ka): lake deepening and intensification of this trend ca. 18 cal ka; Stage III (16.4-11.2 cal ka): rising lake levels with a short term wet phase (13.1-11.7 cal ka); Stage IV (11.2-8.5 cal ka): early Holocene hydrological maxima and highest lake levels inferred to have resulted from early Holocene Indian monsoon intensification, as records from central Asia indicate weaker westerlies during this interval; Stage V (8.5-5.5 cal ka): mid-Holocene climate deterioration; Stage VI (5.5-2.7 cal ka): progressive lowering of lake level; Stage VII (2.7-0 cal ka): onset of modern conditions. The reconstructed hydrological variability in Lake Tso Moriri is governed by temperature changes (meltwater inflow) and monsoon precipitation (increased runoff). A regional comparison shows considerable differences with other palaeorecords from peninsular India during late Holocene. (C) 2014 Elsevier Ltd and INQUA. All rights reserved. KW - Authigenic carbonates KW - Holocene KW - Indian summer monsoon KW - Lake sediments KW - Tso Moriri Lake KW - Westerlies Y1 - 2015 U6 - https://doi.org/10.1016/j.quaint.2014.11.040 SN - 1040-6182 SN - 1873-4553 VL - 371 SP - 76 EP - 86 PB - Elsevier CY - Oxford ER -