457 research outputs found
Heralded photonic interaction between distant single ions
We establish heralded interaction between two remotely trapped single 40Ca+
ions through the exchange of single photons. In the sender ion, we release
single photons with controlled temporal shape on the P_3/2 to D_5/2 transition
and transmit them to the distant receiver ion. Individual absorption events in
the receiver ion are detected by quantum jumps. For continuously generated
photons, the absorption reduces significantly the lifetime of the long-lived
D_5/2 state. For triggered single-photon transmission, we observe coincidence
between the emission at the sender and quantum jump events at the receiver.Comment: 5 pages, 4 figures. v2: number on p. 3, bottom, correcte
Changes in distribution and lengths of Mnemiopsis leidyi in the central Baltic Sea between fall and spring
EXPlainistry: Creating Documentation, Explanations, and Animated Visualizations of Chemistry Experiments Supported by Information and Communication Technology to Help School Students Understand Molecular-Level Interactions
Given that students are constantly communicating and documenting special experiences in their social and private lives with digital devices, we suggest that this behavior could be used to record and deepen learning experiences-such as visualizing reactions at the molecular level-in a chemistry class. An example would be the creation of stop-motion videos to aid the visualization process for the documentation of experiments. This approach makes use of well-established techniques for documentation and visualization (e.g., static models or pictures) and combines them with dynamic approaches (e.g., animations) in order to enhance explanations of chemical experiments. Here, we describe how we use this approach to augment the novel teaching method, EXPlainistry (experiments explained in chemistry) with 5th to 12th graders, and consider how it helps students use ICT (information and communications technology) in order to document, explain, and visualize experiments in chemistry education
The recruitment process in Baltic cod:Spatio-temporal variation in starvation and predation during early life stages with special consideration of the invasive ctenophore Mnemiopsis leidyi
Promoting Education for Sustainable Development with an Interactive Digital Learning Companion Students Use to Perform Collaborative Phosphorus Recovery Experiments and Reporting
Multitouch learning books (MLBs) are learning companions that support learning within a series, independent of the learning location. These MLBs can accompany an experiment itself or an entire learning process. In addition to providing interactive tasks, an all-in-one solution can provide pupils with additional information, supporting and differentiating aids, in-depth exercises, and collaborative tasks in one location. This Article presents an interactive learning companion that facilitates student learning through digital interaction while also developing concepts of sustainability in studentsâ minds. For this purpose, a learning scenario was developed that simulates a virtual learning company in an interactive e-book that corresponds to real experiments carried out in a laboratory. Using this interactive e-book, pupils receive e-mail messages from their âsupervisors,â give account to the âboard of directors,â and finally evaluate four real processes for phosphorus recovery. The entire series was qualitatively tested with 89 tenth-grade students. Assessment of these students found a significant increase in their use and understanding of digital tools and awareness of education for sustainable development concepts
Abundance, horizontal and vertical distribution of the invasive ctenophore Mnemiopsis leidyi in the central Baltic Sea, November 2007
The distribution and abundance of the invasive ctenophore Mnemiopsis leidyi in the Bornholm Basin, an important spawning ground of several fish stocks, and in adjacent areas in the central Baltic Sea was studied in November 2007. The study showed that M. leidyi were relatively small (body length 18.6 ± 7.6 mm) and they were patchily distributed over a large part of the investigated area. Specimens were found on 68 and 59% of stations sampled with a Bongo net (n=39) and an Isaac-Kidd midwater trawl (n=51), respectively. Vertically, the highest densities of M. leidyi occurred at 40 to 60 m around the halocline.
Horizontally, the highest abundances were found north and west of Bornholm, but relatively high densities were also observed in the Slupsk Furrow. The mean abundance was 1.58 ± 2.12 ind. m-2, the peak abundance was 8.92 ind. m-2, and the average and peak population density were 0.03 ± 0.05 and 0.28 ind. m-3, respectively. The abundances are low compared to densities recently observed in other areas of the Baltic region (e. g. Limfjorden, Ă
land Sea) and the estimated predation impact on zooplankton by M. leidyi was negligible in November 2007. However, because of the ctenophoreâs wide distribution in the central Baltic Sea, its ability for rapid population growth, and its potential influence on fish stocks by competing for food and by preying on fish eggs and newly hatched larvae, close monitoring of the future development of M. leidyi in the Baltic Sea is strongly recommended
DAS ISCHĂMISCHE ZEITFENSTER VON EKTOPEM ENDOMETRIUM BESTIMMT SEINE FĂHIGKEIT ZUR AUSBILDUNG VON ENDOMETRIOSEHERDEN : Eine experimentelle in vivo Studie im Endometriosemodell der Maus
Die Endometriose ist definiert als das Vorkommen von Endometrioseherden auĂerhalb des Cavum uteri. Peritoneale Endometrioseherde entstehen hauptsĂ€chlich durch retrograde Menstruation. Hierbei wird wĂ€hrend der Menstruation abgestoĂenes Endometrium durch die Tuben in den Bauchraum transportiert. Dort kann das Gewebe adhĂ€rieren, proliferieren und am Peritoneum anwachsen.
Die retrograde Menstruation ist ein physiologischer Prozess, welcher bei bis zu 90 % aller Frauen nachweisbar ist. Es haben jedoch deutlich weniger Frauen eine Endometriose. Somit scheinen noch andere Kofaktoren bei der Entstehung der Krankheit notwendig zu sein. Dabei ist zu bedenken, dass die in vivo Passage von Endometri-umfragmenten aus dem Uterus durch die Tuben in die Peritonealhöhle einige Stunden bis Tage dauern kann. WĂ€hrend dieser Zeit sind die Fragmente avaskulĂ€r und hypoxischen Bedingungen ausgesetzt. Unklar ist, wie dieser Zustand die ViabilitĂ€t, Proliferation, Angiogenese, EntzĂŒndungsaktivitĂ€t und schlieĂlich die FĂ€higkeit, einen Endometrioseherd auszubilden, beeinflusst.
Ziel der vorliegenden Arbeit war es daher zu untersuchen, wie das ischĂ€mische Zeitfenster zwischen Entnahme und peritonealem Kontakt von Endometrium die Entstehung, GröĂenentwicklung, Angiogenese, Apoptose und Immunzellinfiltration von induzierten Endometrioseherden beeinflusst.
Hierzu wurden in einem ersten Studienabschnitt Uterusfragmente von transgenen C57BL/6-TgN(ACTB-EGFP)1Osb/J-MĂ€usen, deren Gewebe green fluorescent protein (GFP)-positiv ist, isoliert und entweder direkt nach der Entnahme oder nach einer PrĂ€kultivierung von 24h oder 72h histologisch und immunhistochemisch untersucht. Hierbei konnte gezeigt werden, dass die Zell- und MikrogefĂ€Ădichte 72h-prĂ€kultivierter Uterusfragmente im Vergleich zu frisch isolierten und 24h-prĂ€kultivierten Fragmenten signifikant erniedrigt und die Apoptoserate signifikant erhöht ist. ZusĂ€tzlich wurde ein Proteom-Profiler-Maus-Angiogenese-Array zur Detektion von Angiogenese-relevanten Proteinen durchgefĂŒhrt. Sowohl in frischen als auch in prĂ€kultivierten Uterusfragmenten wurden alle untersuchten Proteine exprimiert. Jedoch zeigten die prĂ€kultivierten Uterusfragmente ein deutlich unterschiedliches Expressionsmuster angiogeneserelevanter Proteine gegenĂŒber dem frisch entnommenen Gewebe.
In einem zweiten Studienabschnitt wurden frisch isolierte und prĂ€kultivierte Uterusfragmente von C57BL/6-TgN(ACTB-EGFP)1Osb/J-MĂ€usen an die Bauchwand weiblicher C57BL/6-MĂ€use transplantiert. Die GröĂenentwicklung der so induzierten Endometrioseherde wurde ĂŒber 28 Tage mittels hochauflösender Ultraschallbildgebung untersucht. Am Ende des Versuchs wurden die Herde entnommen und fĂŒr weitere histologische und immunhistochemische Untersuchungen asserviert. Hierbei konnte gezeigt werden, dass die Entwicklung von Endometrioseherden aus 72h-prĂ€kultivierten Uterusfragmenten nahezu vollstĂ€ndig ausblieb. Weiterhin hemmte eine PrĂ€kultivierung ĂŒber 24h die Entstehung von Endometrioseherden. Jedoch wurde das Wachstum einzelner Herde gefördert. Immunhistochemisch konnte nachgewiesen werden, dass die MikrogefĂ€Ădichte sowie der Anteil GFP-positiver BlutgefĂ€Ăe und die Apoptoserate in Herden aus frisch isolierten und 24h-prĂ€kultivierten Fragmenten vergleichbar war, der Anteil proliferierender Stromazellen in Herden der 24h-prĂ€kultivierten Fragmente jedoch signifikant erhöht. Des Weiteren zeigte sich in den prĂ€kultivierten Uterusfragmenten ein signifikant geringerer Anteil an neutrophilen Granulozyten und Makrophagen.
In einem dritten Studienabschnitt wurden frisch isolierte sowie 24h- und 72h-prĂ€kultivierte Endometriumfragmente im Modell der RĂŒckenhautkammer mittels intravitaler Fluoreszenzmikroskopie untersucht. Auf diese Weise konnte gezeigt werden, dass eine PrĂ€kultivierung ĂŒber 24h die Vaskularisierung von Endometriumfrag-menten fördert, wĂ€hrend fast alle 72h-prĂ€kultivierten Endometriumfragmente keine Endometrioseherde mehr ausbilden konnten.
Zusammenfassend zeigt die vorliegende Arbeit, dass die durch eine PrĂ€kultivierung verursachte Gewebehypoxie einen wesentlichen Einfluss auf die IntegritĂ€t, das Ăberleben sowie die angiogene und proliferative AktivitĂ€t von ektopem Endometrium hat. Nach 72h PrĂ€kultivierung regrediert das Gewebe nahezu vollstĂ€ndig und ist nicht mehr in der Lage anzuwachsen und sich zu Endometrioseherden zu entwickeln. Im Gegensatz dazu fördert die 24h avaskulĂ€re Periode die Ăberexpression von angiogenen Wachstumsfaktoren im Gewebe, was zur Ausbildung von Endometrioseherden mit aggressiverem Wachstum fĂŒhrt. Daher könnte die Dauer des ischĂ€mischen Zeitfensters einen wichtigen Selektionsfaktor fĂŒr ektopes Endometrium darstellen, der die Entwicklung von Endometrioseherden innerhalb der Peritonealhöhle bestimmt.Endometriosis is defined as the presence of endometriotic lesions outside the uterine cavity. The primary cause of peritoneal endometriosis is retrograde menstruation. During menstruation, shed endometrium is retrogradely transported through the fallopian tubes into the peritoneal cavity. There, the tissue can adhere and proliferate and engraft into the peritoneum.
Retrograde menstruation is a physiological process, which occurs in up to 90 % of women. However, considerably less women suffer from endometriosis. Thus, other cofactors seem to be necessary to the development of the disease. In this context, it should be considered that in women the passage of shed endometrial fragments from the uterus into the peritoneal cavity and their final engraftment may require several hours to days. During this period, the fragments are avascular and exposed to hypoxic conditions. By now, it is completely unknown, how this affects the survival, proliferation, angiogenesis and inflammatory activity of the tissue and, hence, its ability of developing into endometriotic lesions.
Therefore the aim of the present thesis was to analyze, how the ischemic time window between the explantation and peritoneal contact of endometrium determines the formation, growth, angiogenesis, apoptosis and immune cell infiltration of induced endometriotic lesions.
In a first part of the thesis, uterine fragments from transgenic C57BL/6-TgN(ACTB-EGFP)1Osb/J mice with green fluorescent protein (GFP)-positive tissue were examined directly after their isolation or after precultivation for 24h or 72h by means of histology and immunohistochemistry. The cell density and microvessel density were significantly lower and the apoptosis rate was significantly higher in 72h-precultivated fragments when compared to freshly isolated and 24h-precultivated ones. In addition, a proteome-profiler-mouse-angiogenesis-array was performed to detect angiogenesis-related proteins. All analyzed proteins were detectable in cultivated and non-cultivated uterine fragments. However, the precultivated fragments exhibited a con-siderably different protein expression pattern when compared to the freshly isolated ones.
In a second part of the thesis, freshly isolated and precultivated uterine fragments of C57BL/6-TgN(ACTB-EGFP)1Osb/J-mice were transplanted to the abdominal wall of female C57BL/6 mice. To analyze the growth of these grafts, high-resolution ultra-sound imaging was performed repetitively over 28 days. At the end of the observa-tion period, the endometriotic lesions were excised for further histological and immunohistochemical analyses. It was found that the development of 72h-precultivated uterine fragments into endometriotic lesions was markedly suppressed. Furthermore, a precultivation for 24h also inhibited the development of endometriotic lesions. However, it promoted the growth of individual lesions. The microvessel density, the frac-tion of GFP-positive blood vessels and the rate of apoptosis were comparable in lesions developing from freshly isolated and 24h-precultivated fragments, whereas stromal cells showed a significantly higher proliferation rate in lesions of the 24h-precultivated grafts. The number of macrophages and granulocytes was significantly lower in lesions of precultivated uterine fragments.
In a third part of the thesis, freshly isolated as well as 24h- and 72h-precultivated endometrial fragments were analyzed in the dorsal skinfold chamber model by means of intravital fluorescence microscopy. By this, it could be shown that precultivation of endometrial fragments for 24h promotes their vascularization. In contrast, most of the 72h-precultivated endometrial fragments were not able to develop into endometriotic lesions.
In summary, the present thesis demonstrates that hypoxia induced by precultivation has a strong impact on the integrity, survival as well as the angiogenic and proliferative activity of ectopic endometrium. After 72h of precultivation, the tissue completely regresses and is no longer capable of engrafting and developing into endometriotic lesions. In contrast, an only 24h avascular period promotes the overexpression of angiogenic growth factors in the tissue, leading to the formation of endometriotic lesions which exhibit an aggressive growth behaviour. Therefore, it can be concluded that the duration of the ischemic time window may represent an important selection factor for ectopic endometrium, which determines the development of endometriotic lesions within the peritoneal cavity
Experimental tools for quantum networking operations with single photons and single ions
One promising approach for future quantum networks is the combination of strings of trapped ions as quantum-information processors with entangled photon pairs produced by spontaneous parametric down conversion (SPDC) to establish quantum communication links between distant processing units.
This work reports on experiments using a hybrid quantum-optics set-up, comprising two separate linear ion traps and a resonant SPDC photon-pair source. It demonstrates the controlled interaction of single entangled photon pairs with a single trapped 40Ca+ ion. Preparing the ion as polarization selective absorber in the main polarization bases allows for the reconstruction of the biphoton quantum state, manifesting the photon entanglement in the absorption process.
Beyond that, the thesis documents the implementation of additional experimental tools enabling quantum state transfer experiments from photons to single ions. A dedicated narrowbandwidth laser system is set up, laser sequences are developed for state discrimination and state rotations of ion qubits, and for the creation and characterization of coherent superposition states, of particular importance for state-transfer schemes. Finally, detection efficiencies of single Raman photons emitted by an ion are characterized with a well controlled single-photon source, and absorption probabilities of single photons are determined with a calibrated laser beam, providing precise values to assess efficiencies for different transfer scenarios.Ein mögliches System fĂŒr zukĂŒnftige Quantennetzwerke ist die VerknĂŒpfung gefangener Ionen als Quanteninformationsprozessoren mit durch SPDC (Spontaneous Parametric Down Conversion) erzeugten verschrĂ€nkten Photonenpaaren zum Aufbau von QuantenkommunikationskanĂ€len.
Diese Dissertation behandelt Experimente an einem hybriden Quantenoptikaufbau, bestehend aus zwei separaten linearen Ionenfallen und einer SPDC-Photonenpaarquelle. Sie zeigt die kontrollierte Wechselwirkung einzelner verschrĂ€nkter Photonenpaare mit einem einzelnen 40Ca+ Ion. Durch PrĂ€paration des Ions als polarisationsselektiven Absorber in den drei Hauptpolarisationsbasen, wird der Zwei-Photonen-Quantenzustand rekonstruiert und somit ĂŒber den Absorptionsprozess die VerschrĂ€nkung der Photonenpaare nachgewiesen.
Ăberdies dokumentiert die Arbeit die Einrichtung zusĂ€tzlicher Methoden, welche den Zustandstransfer von Photonen auf einzelne Ionen ermöglichen. Ein schmalbandiges Lasersystem wird aufgebaut, Lasersequenzen fĂŒr Zustandsbestimmung und Zustandsrotationen von Ionen-Qubits und zur Erzeugung und Charakterisierung kohĂ€renter SuperpositionszustĂ€nde werden entwickelt. Ferner werden mit Hilfe einer Einzelphotonenquelle Nachweiseffizienzen fĂŒr einzelne, von einem Ion erzeugte, Raman-Photonen gemessen und Absorptionseffizienzen einzelner Photonen mit einer kalibrierten Laserquelle charakterisiert. Die ermittelten Werte bilden eine solide Grundlage zur AbschĂ€tzung von Erfolgswahrscheinlichkeiten geplanter Transferschemata
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