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Galaxies are surrounded by large reservoirs of gas, mostly hydrogen, that are fed by inflows from the intergalactic medium and by outflows from galactic winds. Absorption-line measurements along the lines of sight to bright and rare background quasars indicate that this circumgalactic medium extends far beyond the starlight seen in galaxies, but very little is known about its spatial distribution. The Lyman-alpha transition of atomic hydrogen at a wavelength of 121.6 nanometres is an important tracer of warm (about 104 kelvin) gas in and around galaxies, especially at cosmological redshifts greater than about 1.6 at which the spectral line becomes observable from the ground. Tracing cosmic hydrogen through its Lyman-a emission has been a long-standing goal of observational astrophysics(1-3), but the extremely low surface brightness of the spatially extended emission is a formidable obstacle. A new window into circumgalactic environments was recently opened by the discovery of ubiquitous extended Lyman-alpha emission from hydrogen around high-redshift galaxies(4,5). Such measurements were previously limited to especially favourable systems(6-8) or to the use of massive statistical averaging(9,10) because of the faintness of this emission. Here we report observations of low-surface-brightness Lyman-alpha emission surrounding faint galaxies at redshifts between 3 and 6. We find that the projected sky coverage approaches 100 per cent. The corresponding rate of incidence (the mean number of Lyman-alpha emitters penetrated by any arbitrary line of sight) is well above unity and similar to the incidence rate of high-column-density absorbers frequently detected in the spectra of distant quasars(11-14). This similarity suggests that most circumgalactic atomic hydrogen at these redshifts has now been detected in emission.
Portal Transfer
(2023)
Liebe Leserinnen und Leser, kein Nachrichtentag vergeht, an dem nicht die Expertise aus der Wissenschaft gefragt ist: Ob zum russischen Angriffskrieg in der Ukraine, zur UNKlimakonferenz in Ägypten, zur Flutkatastrophe in Pakistan, zum Dürresommer, zur Energiekrise, selbst zur umstrittenen Fußballweltmeisterschaft in Katar standen und stehen Expertinnen und Experten in den Medien Rede und Antwort. Auch aus der Universität Potsdam. Wir haben sie gefragt, wie sie damit umgehen, wie es ihnen gelingt, aus der laufenden Forschung heraus aktuelle Probleme zu bewerten. Und was davon bleibt, wenn das öffentliche Interesse abebbt. Für die Potsdamer Politik- und Verwaltungswissenschaftlerin Sabine Kuhlmann besteht die Kunst darin, „außerhalb der Krise Ideen und Lösungsansätze zu verstetigen und sie tatsächlich in die Praxis umzusetzen“.
In unserem Alumni- und Transfermagazin berichten wir davon, was und wie die Universität Potsdam dazu beiträgt. Wir erzählen, wie Erfindungen zu Innovationen in der Wirtschaft werden und sich Start-ups auf den Weg machen, ihr Produkt selbst zu vermarkten. Das Spektrum reicht von Meeresfrüchten auf Pflanzenbasis bis zu einer App, mit der sich Frühformen der Demenz erkennen lassen. Neben neuen Technologien kommt es aber vor allem darauf an, das an der Universität erzeugte Wissen in die Praxis zu transferieren. Deshalb stellen wir ein Programm zur Bekämpfung von Hassrede in der Schule vor oder auch eine Klettertherapie zur Behandlung von Skoliose. Und wir zeigen, wie eine Studie zur sportlichen Leistungskraft von Kindern helfen kann, den Sportunterricht zu verbessern.
Den größten Teil des an der Universität produzierten Wissens tragen die Studierenden in die Welt, wenn sie nach ihrem Abschluss als Musiklehrerin in einer Schule arbeiten oder als Software-Ingenieur im eigenen Unternehmen, als Geologin nach Seltenen Erden schürfen, als Ökologe ausgelaugte Böden wieder fruchtbar machen oder als Politikerin ein Ministerium leiten. Sie alle kommen in diesem Magazin zu Wort. Oder in unserem neuen Podcast „Listen.UP“, in dem Studierende, Forschende und Alumni von ihren Transferprojekten erzählen. Von der Gründerin Ulrike Böttcher erfährt man dort zum Beispiel, wie sie mit Schnallen, Ösen und Knöpfen aus Bio- Materialien die Modeindustrie in diesem Bereich nachhaltig verändern will. Nachzulesen ist das auch in diesem Heft. Immer dort, wo das „Listen. UP“-Logo erscheint, lohnt es, zusätzlich in den Podcast hineinzuhören.
Der Band enthält die Tagungsmaterialien des deutsch-russichen Symposiums zum Thema "Verfassungsentwicklung in Russland und Deutschland", welches am 25. und 26. September 2013 in Potsdam stattfand. Die Tagung wurde anlässlich des 20. Jahrestages der russischen Verfassung vom Dezember 2013 durchgeführt. Die inhaltlichen Schwerpunkte bilden die Themen: Verfassungsentstehung, Verfassungsänderung, Verfassungsprinzipien, Landesverfassungen, Fortentwicklung der Verfassung durch die Verfassungsgerichtsbarkeit und Grundrechte, die jeweils aus russischer und deutscher Sicht behandelt werden. Ergänzend befasst sich jeweils ein Betrag mit aktuellen Problemen der Menschenrechtsverwirklichung in Russland und der Ausländerintegration in Deutschland und Russland im Vergleich.
Of Trees and Birds
(2019)
Gisbert Fanselow’s work has been invaluable and inspiring to many researchers working on syntax, morphology, and information structure, both from a theoretical and from an experimental perspective. This volume comprises a collection of articles dedicated to Gisbert on the occasion of his 60th birthday, covering a range of topics from these areas and beyond. The contributions have in common that in a broad sense they have to do with language structures (and thus trees), and that in a more specific sense they have to do with birds. They thus cover two of Gisbert’s major interests in- and outside of the linguistic world (and perhaps even at the interface).
Quantification of subsurface water fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical water flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled water fluxes in the range of +/- 1.3 md(-1). Pass band filtering provided amplitude differences and phase shifts of the diurnal temperature signal varying with depth depending on water flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to temperature sensor spacing, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with water flux direction only. Temperature time lags of small sensor distances of all setups were found to be insensitive to vertical water flux.
Zanthoxylum leprieurii Guill. and Perr. (Rutaceae) stem bark is used locally in Uganda for treating tuberculosis (TB) and cough-related infections. Lupeol (1), sesamin (2), trans-fagaramide (3), arnottianamide (4), (S)-marmesinin (5), and hesperidin (6) were isolated from the chloroform/methanol (1:1) extract of Z. leprieurii stem bark. Their structures were elucidated using spectroscopic techniques and by comparison with literature data. Furthermore, the extract and isolated compounds were subjected to antimycobacterial activity. The extract exhibited moderate activity against the susceptible (H(37)Rv) TB strain, but weak activity against the multidrug resistant (MDR)-TB strain with minimum inhibitory concentrations (MICs) of 586.0 and 1172.0 mu g/mL, respectively. Compound 3 (trans-fagaramide) showed significant antimycobacterial activity against the susceptible (H(37)Rv) TB strain (MIC 6 mu g/mL), but moderate activity against the MDR-TB strain (MIC 12.2 mu g/mL). Compounds 2, 5, 6, and 1 showed moderate activities against the susceptible (H(37)Rv) strain (MIC 12.2-98.0 mu g/mL) and moderate to weak activities against the MDR-TB strain (MIC 24.4-195.0 mu g/mL). This study reports for the first time the isolation of compounds 1 to 6 from the stem bark of Z leprieurii. trans-Fagaramide (3) may present a vital template in pursuit of novel and highly effective TB drugs.
Flow patterns in conjunction with seasonal and diurnal temperature variations control ecological and biogeochemical conditions in hyporheic sediments. In particular, hyporheic temperatures have a great impact on many temperature-sensitive microbial processes. In this study, we used 3-D coupled water flow and heat transport simulations applying the HydroGeoSphere code in combination with high-resolution observations of hydraulic heads and temperatures to quantify reach-scale water and heat flux across the river-groundwater interface and hyporheic temperature dynamics of a lowland gravel bed river. The model was calibrated in order to constrain estimates of the most sensitive model parameters. The magnitude and variations of the simulated temperatures matched the observed ones, with an average mean absolute error of 0.7 degrees C and an average Nash Sutcliffe efficiency of 0.87. Our results indicate that nonsubmerged streambed structures such as gravel bars cause substantial thermal heterogeneity within the saturated sediment at the reach scale. Individual hyporheic flow path temperatures strongly depend on the flow path residence time, flow path depth, river, and groundwater temperature. Variations in individual hyporheic flow path temperatures were up to 7.9 degrees C, significantly higher than the daily average (2.8 degrees C), but still lower than the average seasonal hyporheic temperature difference (19.2 degrees C). The distribution between flow path temperatures and residence times follows a power law relationship with exponent of about 0.37. Based on this empirical relation, we further estimated the influence of hyporheic flow path residence time and temperature on oxygen consumption which was found to partly increase by up to 29% in simulations.
The analytical evaluation of diurnal temperature variation in riverbed sediments provides detailed information on exchange fluxes between rivers and groundwater. The underlying assumption of the stationary, one-dimensional vertical flow field is frequently violated in natural systems where subsurface water flow often has a significant horizontal component. In this paper, we present a new methodology for identifying the geometry of the subsurface flow field using vertical temperature profiles. The statistical analyses are based on model optimisation and selection and are used to evaluate the shape of vertical amplitude ratio profiles. The method was applied to multiple profiles measured around in-stream geomorphological structures in a losing reach of a gravel bed river. The predominant subsurface flow field was systematically categorised in purely vertical and horizontal (hyporheic, parafluvial) components. The results highlight that river groundwater exchange flux at the head, crest and tail of geomorphological structures significantly deviated from the one-dimensional vertical flow, due to a significant horizontal component. The geometry of the subsurface water flow depended on the position around the geomorphological structures and on the river level. The methodology presented in this paper features great potential for characterising the spatial patterns and temporal dynamics of complex subsurface flow geometries by using measured temperature time series in vertical profiles. (C) 2016 Elsevier B.V. All rights reserved.
The “HPI Future SOC Lab” is a cooperation of the Hasso Plattner Institute (HPI) and industry partners. Its mission is to enable and promote exchange and interaction between the research community and the industry partners.
The HPI Future SOC Lab provides researchers with free of charge access to a complete infrastructure of state of the art hard and software. This infrastructure includes components, which might be too expensive for an ordinary research environment, such as servers with up to 64 cores and 2 TB main memory. The offerings address researchers particularly from but not limited to the areas of computer science and business information systems. Main areas of research include cloud computing, parallelization, and In-Memory technologies.
This technical report presents results of research projects executed in 2018. Selected projects have presented their results on April 17th and November 14th 2017 at the Future SOC Lab Day events.