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Beiträge zur Haemodynamik : 4. Ueber die Bewegung einer Flüssigkeit in ungleich weiten Röhren
(1862)
Neue Acariden
(1879)
Ueber die einheitliche Verschmelzung verschiedenartiger Netzhauteindrücke beim Sehen mit zwei Augen
(1861)
Background The connection of the variable part of the heavy chain (VH) and and the variable part of the light chain (VL) by a peptide linker to form a consecutive polypeptide chain (single chain antibody, scFv) was a breakthrough for the functional production of antibody fragments in Escherichia coli. Being double the size of fragment variable (Fv) fragments and requiring assembly of two independent polypeptide chains, functional Fab fragments are usually produced with significantly lower yields in E. coli. An antibody design combining stability and assay compatibility of the fragment antigen binding (Fab) with high level bacterial expression of single chain Fv fragments would be desirable. The desired antibody fragment should be both suitable for expression as soluble antibody in E. coli and antibody phage display. Results Here, we demonstrate that the introduction of a polypeptide linker between the fragment difficult (Fd) and the light chain (LC), resulting in the formation of a single chain Fab fragment (scFab), can lead to improved production of functional molecules. We tested the impact of various linker designs and modifications of the constant regions on both phage display efficiency and the yield of soluble antibody fragments. A scFab variant without cysteins (scFabdeltaC) connecting the constant part 1 of the heavy chain (CH1) and the constant part of the light chain (CL) were best suited for phage display and production of soluble antibody fragments. Beside the expression system E.coli, the new antibody format was also expressed in Pichia pastoris. Monovalent and divalent fragments (DiFabodies) as well as multimers were characterised. Conclusion A new antibody design offers the generation of bivalent Fab derivates for antibody phage display and production of soluble antibody fragments. This antibody format is of particular value for high throughput proteome binder generation projects, due to the avidity effect and the possible use of common standard sera for detection.
Es sind vorzüglich die Engländer, die über die therapeutische Anwendung des Ammonium bromntum gearbeitet haben und dasselbe als nützlich in versohiedenen Nervenleiden preisen. (Gibb, Ritchie, Harley , Belgrave). Wir benutzten dasselbe auch vielfach in der Kinderklinik in Petersburg und besonders beim Keuchhusten, aber wenn wir auch einigermaassen die Krankheits-Anfälle abnehmen sahen, so trat diese Abnahme doch lange nicht in dem Grade ein, wie sie Gibb beobachtet haben will, und wonach er das Präparat als Radicalmittel gegen den Keuchhusten empfehlen zu können glaubt. Die Meinungen über die Art der Wirkung dieses Mittels sind getheilt. Belgrave will demselben die Wirkung des Kalium bromatum zuschreiben, nur in etwas geringerem Grade; Gibb vindicirt für dasselbe eine besondere Einwirkung auf die Empfindungsnerven des Schlundes; Binz, der es in einer Keuchhusten-Epidemie viel benutzte, behauptet, dass dasselbe gar keine Vorzüge vor dem Salmiak haben soll. Wir sahen uns daher veranlasst, um die Wirkung dieses Mittels genauer zu ermitteln, eine Reihe von Untersuchungen an verschiedenen Thieren anzustellen, und wir wollen hier kurz die Resultate dieser Untersuchungen mittheilen.
Tête un peu moins large que le thorax, un peu luisante, finement et peu densement ponctuée, toute noire; les poils du vertex et des joues plus abondants, fauves, ceux de la face plus courts, plus rares, et roux; le chaperon presque nu, inégalement ponctué, subrugueux, tronqué droit au bout et margué d'une ligne enfoncée parallèle au bord: flagellum des antennes d'un noir de poix, le premier article long et mince, les autres plus épais, formant une massue longue et faiblement comprimée. ...
Für die Bearbeitbarkeit der der landwirthschaftlichen Kultur unterworfenen Bodenarten sind verschiedene Umstände maßgebend. Als solche kommen hauptsächlich die Kohäreszenz, das Volumgewicht der Böden, sowie die Adhäsion und Reibung derselben an den Ackerwerkzeugen in Betracht. Ueber erstere beiden Eigenschaften liegen ausführlichere Untersuchungen von H. Puchner und E. Wollny vor, während die Adhäsion des Erdreichs an Holz und Eisen bisher nur eine oberflächliche Bearbeitung erfahren hat, und die Reibung der Ackererde, an den Werkzeugen überhaupt nicht bestimmt wurde. Es schien mir daher angezeigt, durch das Experiment die Momente näher festzustellen, welche bei Beurtheilung der beiden zuletzt erwähnten Eigenschaften besonders berücksichtigt werden müssen.
Background The Radical Pair model proposes that magnetoreception is a light-dependent process. Under low monochromatic light from the short-wavelength part of the visual spectrum, migratory birds show orientation in their migratory direction. Under monochromatic light of higher intensity, however, they showed unusual preferences in other directions or axial preferences. To determine whether or not these responses are still controlled by the respective light regimes, European robins, Erithacus rubecula, were tested under UV, Blue, Turquoise and Green light at increasing intensities, with orientation in migratory direction serving as a criterion whether or not magnetoreception works in the normal way. Results Under low light with a quantal flux of 8 times 10 to 15 power quanta s-1 m-2, the birds were well oriented in their seasonally appropriate migratory direction under 424 nm Blue, 502 nm Turquoise and 565 nm Green light, indicating unimpaired magnetoreception. Under 373 nm UV of the same quantal flux, they were not oriented in migratory direction, showing a preference of the east-west axis instead, but they showed excellent orientation in migratory direction under UV of lower intensity. Intensities of above 36 times 10 to 15 power quanta s-1 m-2 of Blue, Turquoise and Green light elicited a variety of responses: disorientation, headings along the east-west axis, headings along the north-south axis or 'fixed' direction tendencies. These responses changed as the intensity was increased from 36 times 10 to the 15 power quanta s-1 m-2 to 54 and 72 times 10 to 15 power quanta s-1 m-2. Conclusion The specific manifestation of responses in directions other than migratory direction clearly depends on the ambient light regime. This implies that although mechanisms normally providing magnetic compass information seem disrupted, processes that are activated by light still control the behavior. It suggests complex interactions between different types of receptors, magnetic and visual. The nature of the receptors involved and details of their connections are not yet known; however, a role of the color cones in the processes mediating magnetic input is suggested.
Gruppenbasiertes vernetztes Lernen im Internet: Design einer virtuellen Hochschulveranstaltung
(1998)
Lernen in virtuellen Veranstaltungen im Internet muß keine einsame Sache sein: gruppenbasierte Veranstaltungskonzepte ermöglichen dezentral verteilte Teilnehmer im Netz zusammenzuführen und gleichzeitig vor Ort Lernprozesse in Gruppen stattfinden zu lassen. Neben der didaktischen Gestaltung eines solches Konzeptes steht der optimale Einsatz eines internetbasierten Medienmix im Mittelpunkt dieses Beitrags. Dieses virtuelle Konzept wird weniger zur Umsetzung von eher vortragsorientierten Hochschulveranstaltungen wie Vorlesungen genutzt, sondern vielmehr um das eigenständige Erarbeiten von Lerninhalten durch die Studierenden zu fördern und didaktische Methoden des problemorientierten, projektorientierten und forschenden Lernens zu integrieren. Übungen, Tutorien, Kolloquien und Seminare können über räumliche Grenzen hinweg mit Teilnehmern an verschiedenen Standorten und damit wohnorts-, universitäts- und länderübergreifend durchgeführt werden.
Perspectives on the educational market: universities between virtual campus and education brokers
(2001)
Nowadays information and communication technologies are affecting many aspects of our daily life. Sitting at our home computer we can order products, book flights, transfer money, buy and sell stocks and take online classes of educational institutions at the other end of the world. Maybe one day we will be able to pick any graduate business course at any institution that we like and combine credits of several online universities. Major changes are happening on the educational market. How will the educational market look like in 10 or 20 years? Which path will the traditional universities go from now on and where will they end? And: what are the factors that influence this shift? These are the questions which are addressed in this paper. Some of the analysis presented in this paper is based on papers published by the German Bertelsmann Stiftung and the Heinz Nixdorf Stiftung (Encarnacao/Leidhold/Reuter 2000) and on some English authors (i.e. Daniel 1998) and it summarizes some of their ideas.
Eine wichtige Zielsetzung bei der Gestaltung und Unterstützung von online Diskursen ist die Motivation der Teilnehmenden zur aktiven Partizipation. Aspekte wie die technische Umsetzung, Zugangsregulierungen, Dauer und Art des Diskurses usw. zielen darauf ab, Teilnehmenden eine möglichst leicht handhabbare und aktive Beteiligung zu ermöglichen. Neben Fragen der technischen Umsetzung sind auch Gestaltungsaspekte wie Dauer und Phasen des Diskurses, sogenannte "Diskursdramaturgie", Beteiligungsformen und -formate, Zugangsrechte, Moderationsmethoden, Formen der Ergebnissicherung und Dokumentation zu planen.
Die Postmoderne beschreibt die Fragmentierung der Gesellschaft, in der Systemrationalitäten miteinander kollidieren. Diese Diagnose kann für die Konzeption der Grundrechte nicht folgenlos bleiben. Der Aufsatz fokussiert zwei Ansätze einer neuen Verfassungstheorie. Grundlagen sind Karl-Heinz Ladeurs Kritik der Abwägung und Gunther Teubners Konzept einer Zivilverfassung vor dem Hintergrund seines Matrixmodells.
Die Rechtspraxis setzt etwas voraus, das sie nicht nur begründet oder ergänzt, sondern grundsätzlich in Frage stellt. So macht der Zwang, in einem Verfahren zu entscheiden und zu begründen, zugleich deutlich, dass jede Form der Entscheidung unangemessen, unbegründet und in ganz anderer Weise neu herzustellen ist. Das ist das juridische Supplement im Geiste von Jacques Derrida. Supplementiert wird die Wahrheit des Rechts in anderen Medien: in Drama, Film und Literatur etwa. Dort wird in Szene gesetzt, was in der real erlebbaren Rechtswelt nicht wirklich erlebt werden kann, was aber doch – wie kein Amtsträger bestreiten würde – zum Verfahrensergebnis gehört.
This paper addresses the task of designing an online course. Which considerations have to be made? Many factors have to be regarded: technical options, the didactical design, the institution, the subject of the courses and the students. This task becomes even more difficult when we get aware that these factors are very much independent and that the decision in one field cannot be made without considering the others aspects. The didactical design of an online course has to be implemented based on technical option in order to shape and support the teaching and learning process. Different internet media can be uses such as web pages, email, discussion boards and chats as well as specialized software packages. These media types are characterized by certain functionalities which are appropriate for certain learning methods. What are the factors which influence this choice? Besides the aspect of synchronization the technical equipment at the learners' place and their media competence is essential. Additionally CD ROMs can be used as a media for data transmission as well as a supportive function for the learning process. The didactical design of a CD ROM can support different learning methods and provide additional learning material which can be used according to the students' demands. In this paper some examples are given as how to implement different didactical elements with different technical features. The learning process does not have to take place on the level of the individual learner but should integrate social interaction in different social forms. learning can take place on different levels such the individual learner, small groups, and plenary settings. But:: group learning processes have to be properly planned and pre-structured in the didactical design of online courses and need sufficient technical support in order to work properly.
Hochschulen müssen sich im Hinblick auf e-Learning mit der Frage konfrontieren, welche Strategien sie langfristig erfolgen wollen, an denen sie infrastrukturelle Maßnahmen und Unterstützungsangebote für Hochschullehrende ausrichten können. Neben einer bisher eher vielfältigen e-Learning Landschaft an Hochschulen lässt sich der längerfristige Einsatz neuer Medien in der Hochschullehre nur dann erfolgreich – und damit nachhaltig – gestalten, wenn Hochschulen und Politik sich mit grundsätzlichen strategischen Fragestellungen befassen. Dieser Beitrag beleuchtet einige dieser Fragen und gibt anschauliche Beispiele möglicher Lösungsansätze. Gleichzeitig wird auf das Innovationspotenzial neuer Medien in der Lehre hingewiesen, das sich auf der Ebene einzelner Lehrveranstaltungen, wie auch im Hinblick auf die curriculare Ausrichtung ganzer Fachbereiche auswirken kann. Letztendlich sollten neue Medien aber vor allem einen didaktischen und pädagogischen Mehrwert für die Hochschullehre erschließen.
Die Substanztheorie bei Cartesius im Zusammenhang mit der scholastischen und neueren Philosophie
(1892)
The article explores the increasing gap between the cultural dynamics of transnationalization in Germany and the national self-perception of the German society. While concepts of “in-migration” (Zuwanderung) and ”integration” still stick to notions of the nation-state as being a ”container” embracing and controlling a population and a culture of its own, the various processes of material and imaginary mobility across the national borders contradict and challenge this notion as well as its political implications. By drawing on the transnational lifeworlds and the cultural productivity of migrants, anthropological research has made important contributions to render visible this challenge. It is argued, however, that an all too exclusive focus on migration may, in fact, rather conceal the wider effects of transnationalisation and cultural globalisation on the society and its cultural fabric as a whole.
Background The Deltaretrovirus genus comprises viruses that infect humans (HTLV), various simian species (STLV) and cattle (BLV). HTLV-I is the main causative agent in adult T-cell leukemia in endemic areas and some of the simian T-cell lymphotropic viruses have been implicated in the induction of malignant lymphomas in their hosts. BLV causes enzootic bovine leukosis in infected cattle or sheep. During the past few years several new Deltaretrovirus isolates have been described in various primate species. Two new HTLV-like viruses in humans have recently been identified and provisionally termed HTLV-III and HTLV-IV. In order to identify a broad spectrum of Deltaretroviruses by a single PCR approach we have established a novel consensus PCR based on nucleotide sequence data obtained from 42 complete virus isolates (HTLV-I/-II, STLV-I/-II/-III, BLV). The primer sequences were based on highly interspecies-conserved virus genome regions. We used this PCR to detect Deltaretroviruses in samples from adult patients with a variety of rare T-cell neoplasms in Germany. Results: The sensitivity of the consensus PCR was at least between 10-2 and 10-3 with 100% specificity as demonstrated by serial dilutions of cell lines infected with either HTLV-I, HTLV-II or BLV. Fifty acute T-cell lymphoblastic leukemia (T-ALL) samples and 33 samples from patients with various rare mature T-cell neoplasms (T-PLL, Sezary syndrome and other T-NHL) were subsequently investigated. There were no cases with HTLV-I, HTLV-II or any other Deltaretroviruses. Conclusions: The results rule out a significant involvement of HTLV-I or HTLV-II in these disease entities and show that other related Deltaretroviruses are not likely to be involved. The newly established Deltaretrovirus PCR may be a useful tool for identifying new Deltaretroviruses.
Background A procedure for including activity against enveloped viruses in the post-contamination treatment of hands has been recommended, but so far no European standard is available to implement it. In 2004, the German Robert Koch-Institute (RKI) and the German Association for the Control of Virus Disease (DVV) suggested that vaccinia virus and bovine viral diarrhea virus (BVDV) should be used as test viruses in a quantitative suspension test to determine the activity of a disinfectant against all enveloped viruses. Methods We have studied the activities of three commonly-used alcohol-based hand rubs (hand rub A, based on 45% propan-2-ol, 30% propan-1-ol and 0.2% mecetronium etilsulfate; hand rub B, based on 80% ethanol; hand rub C, based on 95% ethanol) against vaccinia virus and BVDV, and in addition against four other clinically relevant enveloped viruses: herpes simplex virus (HSV) types 1 and 2, and human and avian influenza A virus. The hand rubs were challenged with different organic loads at exposure time of 15, 30 and 60 s. According to the guidelines of both BGA/RKI and DVV, and EN 14476:2005, the reduction of infectivity of each test virus was measured on appropriate cell lines using a quantitative suspension test. Results All three alcohol-based hand rubs reduced the infectivity of vaccinia virus and BVDV by >= 4 log10-steps within 15 s, irrespective of the type of organic load. Similar reductions of infectivity were seen against the other four enveloped viruses within 15 s in the presence of different types of organic load. Conclusions Commonly used alcohol-based hand rubs with a total alcohol concentration >= 75% can be assumed to be active against clinically relevant enveloped viruses if they effectively reduce the infectivities of vaccinia virus and BVDV in a quantitative suspension test.
Aus dem Engeren : Litteraturbilder aus deutschen Einzelgauen ; IV: von der pommerschen Waterkant´
(1898)
Mechanisms by which subvisible cirrus clouds (SVCs) might contribute to dehydration close to the tropical tropopause are not well understood. Recently Ultrathin Tropical Tropopause Clouds (UTTCs) with optical depths around 10-4 have been detected in the western Indian ocean. These clouds cover thousands of square kilometers as 200-300 m thick distinct and homogeneous layer just below the tropical tropopause. In their condensed phase UTTCs contain only 1-5% of the total water, and essentially no nitric acid. A new cloud stabilization mechanism is required to explain this small fraction of the condensed water content in the clouds and their small vertical thickness. This work suggests a mechanism, which forces the particles into a thin layer, based on upwelling of the air of some mm/s to balance the ice particles, supersaturation with respect to ice above and subsaturation below the UTTC. In situ measurements suggest that these requirements are fulfilled. The basic physical properties of this mechanism are explored by means of a single particle model. Comprehensive 1-D cloud simulations demonstrate this stabilization mechanism to be robust against rapid temperature fluctuations of +/- 0.5 K. However, rapid warming (Delta T > 2 K) leads to evaporation of the UTTC, while rapid cooling (Delta T < -2 K) leads to destabilization of the particles with the potential for significant dehydration below the cloud
Obstacle detection is an important part of Video Processing because it is indispensable for a collision prevention of autonomously navigating moving objects. For example, vehicles driving without human guidance need a robust prediction of potential obstacles, like other vehicles or pedestrians. Most of the common approaches of obstacle detection so far use analytical and statistical methods like motion estimation or generation of maps. In the first part of this contribution a statistical algorithm for obstacle detection in monocular video sequences is presented. The proposed procedure is based on a motion estimation and a planar world model which is appropriate to traffic scenes. The different processing steps of the statistical procedure are a feature extraction, a subsequent displacement vector estimation and a robust estimation of the motion parameters. Since the proposed procedure is composed of several processing steps, the error propagation of the successive steps often leads to inaccurate results. In the second part of this contribution it is demonstrated, that the above mentioned problems can be efficiently overcome by using Cellular Neural Networks (CNN). It will be shown, that a direct obstacle detection algorithm can be easily performed, based only on CNN processing of the input images. Beside the enormous computing power of programmable CNN based devices, the proposed method is also very robust in comparison to the statistical method, because is shows much less sensibility to noisy inputs. Using the proposed approach of obstacle detection in planar worlds, a real time processing of large input images has been made possible.
Measurements of OH, total peroxy radicals, non-methane hydrocarbons (NMHCs) and various other trace gases were made at the Meteorological Observatory Hohenpeissenberg in June 2000. The data from an intensive measurement period characterised by high solar insolation (18-21 June) are analysed. The maximum midday OH concentration ranged between 4.5x106 molecules cm-3 and 7.4x106 molecules cm-3. The maximum total ROx (ROx =OH+RO+HO2+RO2) mixing ratio increased from about 55 pptv on 18 June to nearly 70 pptv on 20 and 21 June. A total of 64 NMHCs, including isoprene and monoterpenes, were measured every 1 to 6 hours. The oxidation rate of the NMHCs by OH was calculated and reached a total of over 14x106 molecules cm-3 s-1 on two days. A simple photostationary state balance model was used to simulate the ambient OH and peroxy radical concentrations with the measured data as input. This approach was able to reproduce the main features of the diurnal profiles of both OH and peroxy radicals. The balance equations were used to test the effect of the assumptions made in this model. The results proved to be most sensitive to assumptions about the impact of unmeasured volatile organic compounds (VOC), e.g. formaldehyde (HCHO), and about the partitioning between HO2 and RO2. The measured OH concentration and peroxy radical mixing ratios were reproduced well by assuming the presence of 3 ppbv HCHO as a proxy for oxygenated hydrocarbons, and a HO2/ RO2 ratio between 1:1 and 1:2. The most important source of OH, and conversely the greatest sink for peroxy radicals, was the recycling of HO2 radicals to OH. This reaction was responsible for the recycling of more than 45x106 molecules cm-3 s-1 on two days. The most important sink for OH, and the largest source of peroxy radicals, was the oxidation of NMHCs, in particular, of isoprene and the monoterpenes.
Subvisible cirrus clouds (SVCs) may contribute to dehydration close to the tropical tropopause. The higher and colder SVCs and the larger their ice crystals, the more likely they represent the last efficient point of contact of the gas phase with the ice phase and, hence, the last dehydrating step, before the air enters the stratosphere. The first simultaneous in situ and remote sensing measurements of SVCs were taken during the APE-THESEO campaign in the western Indian ocean in February/March 1999. The observed clouds, termed Ultrathin Tropical Tropopause Clouds (UTTCs), belong to the geometrically and optically thinnest large-scale clouds in the Earth´s atmosphere. Individual UTTCs may exist for many hours as an only 200--300 m thick cloud layer just a few hundred meters below the tropical cold point tropopause, covering up to 105 km2. With temperatures as low as 181 K these clouds are prime representatives for defining the water mixing ratio of air entering the lower stratosphere.
We have used the SLIMCAT 3-D off-line chemical transport model (CTM) to quantify the Arctic chemical ozone loss in the year 2002/2003 and compare it with similar calculations for the winters 1999/2000 and 2003/2004. Recent changes to the CTM have improved the model's ability to reproduce polar chemical and dynamical processes. The updated CTM uses σ-θ as a vertical coordinate which allows it to extend down to the surface. The CTM has a detailed stratospheric chemistry scheme and now includes a simple NAT-based denitrification scheme in the stratosphere.
In the model runs presented here the model was forced by ECMWF ERA40 and operational analyses. The model used 24 levels extending from the surface to ~55km and a horizontal resolution of either 7.5° x 7.5° or 2.8° x 2.8°. Two different radiation schemes, MIDRAD and the CCM scheme, were used to diagnose the vertical motion in the stratosphere. Based on tracer observations from balloons and aircraft, the more sophisticated CCM scheme gives a better representation of the vertical transport in this model which includes the troposphere. The higher resolution model generally produces larger chemical O3 depletion, which agrees better with observations.
The CTM results show that very early chemical ozone loss occurred in December 2002 due to extremely low temperatures and early chlorine activation in the lower stratosphere. Thus, chemical loss in this winter started earlier than in the other two winters studied here. In 2002/2003 the local polar ozone loss in the lower stratosphere was ~40% before the stratospheric final warming. Larger ozone loss occurred in the cold year 1999/2000 which had a persistently cold and stable vortex during most of the winter. For this winter the current model, at a resolution of 2.8° x 2.8°, can reproduce the observed loss of over 70% locally. In the warm and more disturbed winter 2003/2004 the chemical O3 loss was generally much smaller, except above 620K where large losses occurred due to a period of very low minimum temperatures at these altitudes.
Number concentrations of total and non-volatile aerosol particles with size diameters >0.01 μm as well as particle size distributions (0.4–23 μm diameter) were measured in situ in the Arctic lower stratosphere (10–20.5 km altitude). The measurements were obtained during the campaigns European Polar Stratospheric Cloud and Lee Wave Experiment (EUPLEX) and Envisat-Arctic-Validation (EAV). The campaigns were based in Kiruna, Sweden, and took place from January to March 2003. Measurements were conducted onboard the Russian high-altitude research aircraft Geophysica using the low-pressure Condensation Nucleus Counter COPAS (COndensation PArticle Counter System) and a modified FSSP 300 (Forward Scattering Spectrometer Probe). Around 18–20 km altitude typical total particle number concentrations nt range at 10–20 cm−3 (ambient conditions). Correlations with the trace gases nitrous oxide (N2O) and trichlorofluoromethane (CFC-11) are discussed. Inside the polar vortex the total number of particles >0.01 μm increases with potential temperature while N2O is decreasing which indicates a source of particles in the above polar stratosphere or mesosphere. A separate channel of the COPAS instrument measures the fraction of aerosol particles non-volatile at 250°C. Inside the polar vortex a much higher fraction of particles contained non-volatile residues than outside the vortex (~67% inside vortex, ~24% outside vortex). This is most likely due to a strongly increased fraction of meteoric material in the particles which is transported downward from the mesosphere inside the polar vortex. The high fraction of non-volatile residual particles gives therefore experimental evidence for downward transport of mesospheric air inside the polar vortex. It is also shown that the fraction of non-volatile residual particles serves directly as a suitable experimental vortex tracer. Nanometer-sized meteoric smoke particles may also serve as nuclei for the condensation of gaseous sulfuric acid and water in the polar vortex and these additional particles may be responsible for the increase in the observed particle concentration at low N2O. The number concentrations of particles >0.4 μm measured with the FSSP decrease markedly inside the polar vortex with increasing potential temperature, also a consequence of subsidence of air from higher altitudes inside the vortex. Another focus of the analysis was put on the particle measurements in the lowermost stratosphere. For the total particle density relatively high number concentrations of several hundred particles per cm3 at altitudes below ~14 km were observed in several flights. To investigate the origin of these high number concentrations we conducted air mass trajectory calculations and compared the particle measurements with other trace gas observations. The high number concentrations of total particles in the lowermost stratosphere are probably caused by transport of originally tropospheric air from lower latitudes and are potentially influenced by recent particle nucleation.
We report measurements of the deuterium content of molecular hydrogen (H2) obtained from a suite of air samples that were collected during a stratospheric balloon flight between 12 and 33 km at 40º N in October 2002. Strong deuterium enrichments of up to 400 permil versus Vienna Standard Mean Ocean Water (VSMOW) are observed, while the H2 mixing ratio remains virtually constant. Thus, as hydrogen is processed through the H2 reservoir in the stratosphere, deuterium is accumulated in H2 . Using box model calculations we investigated the effects of H2 sources and sinks on the stratospheric enrichments. Results show that considerable isotope enrichments in the production of H2 from CH4 must take place, i.e., deuterium is transferred preferentially to H2 during the CH4 oxidation sequence. This supports recent conclusions from tropospheric H2 isotope measurements which show that H2 produced photochemically from CH4 and non-methane hydrocarbons must be enriched in deuterium to balance the tropospheric hydrogen isotope budget. In the absence of further data on isotope fractionations in the individual reaction steps of the CH4 oxidation sequence, this effect cannot be investigated further at present. Our measurements imply that molecular hydrogen has to be taken into account when the hydrogen isotope budget in the stratosphere is investigated.
Balloon-borne measurements of CFC11 (from the DIRAC in situ gas chromatograph and the DESCARTES grab sampler), ClO and O3 were made during the 1999/2000 Arctic winter as part of the SOLVE-THESEO 2000 campaign, based in Kiruna (Sweden). Here we present the CFC11 data from nine flights and compare them first with data from other instruments which flew during the campaign and then with the vertical distributions calculated by the SLIMCAT 3D CTM. We calculate ozone loss inside the Arctic vortex between late January and early March using the relation between CFC11 and O3 measured on the flights. The peak ozone loss (~1200ppbv) occurs in the 440-470K region in early March in reasonable agreement with other published empirical estimates. There is also a good agreement between ozone losses derived from three balloon tracer data sets used here. The magnitude and vertical distribution of the loss derived from the measurements is in good agreement with the loss calculated from SLIMCAT over Kiruna for the same days.
Turbulent fluxes of carbonyl sulfide (COS) and carbon disulfide (CS2) were measured over a spruce forest in Central Germany using the relaxed eddy accumulation (REA) technique. A REA sampler was developed and validated using simultaneous measurements of CO2 fluxes by REA and by eddy correlation. REA measurements were conducted during six campaigns covering spring, summer, and fall between 1997 and 1999. Both uptake and emission of COS and CS2 by the forest were observed, with deposition occurring mainly during the sunlit period and emission mainly during the dark period. On the average, however, the forest acts as a sink for both gases. The average fluxes for COS and CS2 are -93 ± 11.7 pmol m-2 s-1 and -18 ± 7.6 pmol m-2 s-1, respectively. The fluxes of both gases appear to be correlated to photosynthetically active radiation and to the CO2 and \chem{H_2O} fluxes, supporting the idea that the air-vegetation exchange of both gases is controlled by stomata. An uptake ratio COS/CO2 of 10 ± 1.7 pmol m mol-1 has been derived from the regression line for the correlation between the COS and CO2 fluxes. This uptake ratio, if representative for the global terrestrial net primary production, would correspond to a sink of 2.3 ± 0.5 Tg COS yr-1.
A comprehensive set of stratospheric balloon and aircraft samples was analyzed for the position-dependent isotopic composition of nitrous oxide (N2O). Results for a total of 220 samples from between 1987 and 2003 are presented, nearly tripling the number of mass-spectrometric N2O isotope measurements in the stratosphere published to date. Cryogenic balloon samples were obtained at polar (Kiruna/Sweden, 68° N), mid-latitude (southern France, 44° N) and tropical sites (Hyderabad/India, 18° N). Aircraft samples were collected with a newly-developed whole air sampler on board of the high-altitude aircraft M55 Geophysica during the EUPLEX 2003 campaign. For mixing ratios above 200 nmol mol−1, relative isotope enrichments (δ values) and mixing ratios display a compact relationship, which is nearly independent of latitude and season and which can be explained equally well by Rayleigh fractionation or mixing. However, for mixing ratios below 200 nmol mol−1 this compact relationship gives way to meridional, seasonal and interannual variations. A comparison to a previously published mid-latitude balloon profile even shows large zonal variations, justifying the use of three-dimensional (3-D) models for further data interpretation.
In general, the magnitude of the apparent fractionation constants (i.e., apparent isotope effects) increases continuously with altitude and decreases from the equator to the North Pole. Only the latter observation can be understood qualitatively by the interplay between the time-scales of N2O photochemistry and transport in a Rayleigh fractionation framework. Deviations from Rayleigh fractionation behavior also occur where polar vortex air mixes with nearly N2O-free upper stratospheric/mesospheric air (e.g., during the boreal winters of 2003 and possibly 1992). Aircraft observations in the polar vortex at mixing ratios below 200 nmol mol−1 deviate from isotope variations expected for both Rayleigh fractionation and two-end-member mixing, but could be explained by continuous weak mixing between intravortex and extravortex air (Plumb et al., 2000). However, it appears that none of the simple approaches described here can capture all features of the stratospheric N2O isotope distribution, again justifying the use of 3-D models. Finally, correlations between 18O/16O and average 15N/14N isotope ratios or between the position-dependent 15N/14N isotope ratios show that photo-oxidation makes a large contribution to the total N2O sink in the lower stratosphere (possibly up to 100% for N2O mixing ratios above 300 nmol mol−1). Towards higher altitudes, the temperature dependence of these isotope correlations becomes visible in the stratospheric observations.
Balloon-borne stratospheric BrO measurements: comparison with Envisat/SCIAMACHY BrO limb profiles
(2006)
For the first time, results of all four existing stratospheric BrO profiling instruments, are presented and compared with reference to the SLIMCAT 3-dimensional chemical transport model (3-D CTM). Model calculations are used to infer a BrO profile validation set, measured by 3 different balloon sensors, for the new Envisat/SCIAMACHY (ENVIronment SATellite/SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) satellite instrument. The balloon observations include (a) balloon-borne in situ resonance fluorescence detection of BrO, (b) balloon-borne solar occultation DOAS measurements (Differential Optical Absorption Spectroscopy) of BrO in the UV, and (c) BrO profiling from the solar occultation SAOZ (Systeme d'Analyse par Observation Zenithale) balloon instrument. Since stratospheric BrO is subject to considerable diurnal variation and none of the measurements are performed close enough in time and space for a direct comparison, all balloon observations are considered with reference to outputs from the 3-D CTM. The referencing is performed by forward and backward air mass trajectory calculations to match the balloon with the satellite observations. The diurnal variation of BrO is considered by 1-D photochemical model calculation along the trajectories. The 1-D photochemical model is initialised with output data of the 3-D model with additional constraints on the vertical transport, the total amount and photochemistry of stratospheric bromine as given by the various balloon observations. Total [Bry]=(20.1±2.8)pptv obtained from DOAS BrO observations at mid-latitudes in 2003, serves as an upper limit of the comparison. Most of the balloon observations agree with the photochemical model predictions within their given error estimates. First retrieval exercises of BrO limb profiling from the SCIAMACHY satellite instrument agree to <±50% with the photochemically-corrected balloon observations, and tend to show less agreement below 20 km.
During SPURT (Spurenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region) we performed measurements of a wide range of trace gases with different lifetimes and sink/source characteristics in the northern hemispheric upper troposphere (UT) and lowermost stratosphere (LMS). A large number of in-situ instruments were deployed on board a Learjet 35A, flying at altitudes up to 13.7 km, at times reaching to nearly 380 K potential temperature. Eight measurement campaigns (consisting of a total of 36 flights), distributed over all seasons and typically covering latitudes between 35° N and 75° N in the European longitude sector (10° W–20° E), were performed. Here we present an overview of the project, describing the instrumentation, the encountered meteorological situations during the campaigns and the data set available from SPURT. Measurements were obtained for N2O, CH4, CO, CO2, CFC12, H2, SF6, NO, NOy, O3 and H2O. We illustrate the strength of this new data set by showing mean distributions of the mixing ratios of selected trace gases, using a potential temperature – equivalent latitude coordinate system. The observations reveal that the LMS is most stratospheric in character during spring, with the highest mixing ratios of O3 and NOy and the lowest mixing ratios of N2O and SF6. The lowest mixing ratios of NOy and O3 are observed during autumn, together with the highest mixing ratios of N2O and SF6 indicating a strong tropospheric influence. For H2O, however, the maximum concentrations in the LMS are found during summer, suggesting unique (temperature- and convection-controlled) conditions for this molecule during transport across the tropopause. The SPURT data set is presently the most accurate and complete data set for many trace species in the LMS, and its main value is the simultaneous measurement of a suite of trace gases having different lifetimes and physical-chemical histories. It is thus very well suited for studies of atmospheric transport, for model validation, and for investigations of seasonal changes in the UT/LMS, as demonstrated in accompanying and elsewhere published studies.
During several balloon flights inside the Arctic polar vortex in early 2003, unusual trace gas distributions were observed, which indicate a strong influence of mesospheric air in the stratosphere. The tuneable diode laser (TDL) instrument SPIRALE (Spectroscopie InFrarouge par Absorption de Lasers Embarqués) measured unusually high CO values (up to 600 ppb) on 27 January at about 30 km altitude. The cryosampler BONBON sampled air masses with very high molecular Hydrogen, extremely low SF6 and enhanced CO values on 6 March at about 25 km altitude. Finally, the MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) Fourier Transform Infra-Red (FTIR) spectrometer showed NOy values which are significantly higher than NOy* (the NOy derived from a correlation between N2O and NOy under undisturbed conditions), on 21 and 22 March in a layer centred at 22 km altitude. Thus, the mesospheric air seems to have been present in a layer descending from about 30 km in late January to 25 km altitude in early March and about 22 km altitude on 20 March. We present corroborating evidence from a model study using the KASIMA (KArlsruhe Simulation model of the Middle Atmosphere) model that also shows a layer of mesospheric air, which descended into the stratosphere in November and early December 2002, before the minor warming which occurred in late December 2002 lead to a descent of upper stratospheric air, cutting of a layer in which mesospheric air is present. This layer then descended inside the vortex over the course of the winter. The same feature is found in trajectory calculations, based on a large number of trajectories started in the vicinity of the observations on 6 March. Based on the difference between the mean age derived from SF6 (which has an irreversible mesospheric loss) and from CO2 (whose mesospheric loss is much smaller and reversible) we estimate that the fraction of mesospheric air in the layer observed on 6 March, must have been somewhere between 35% and 100%.
A new version of a digital global map of irrigation areas was developed by combining irrigation statistics for 10 825 sub-national statistical units and geo-spatial information on the location and extent of irrigation schemes. The map shows the percentage of each 5 arc minute by 5 arc minute cell that was equipped for irrigation around the year 2000. It is thus an important data set for global studies related to water and land use. This paper describes the data set and the mapping methodology and gives, for the first time, an estimate of the map quality at the scale of countries, world regions and the globe. Two indicators of map quality were developed for this purpose, and the map was compared to irrigated areas as derived from two remote sensing based global land cover inventories.
Flow velocity in rivers has a major impact on residence time of water and thus on high and low water as well as on water quality. For global scale hydrological modeling only very limited information is available for simulating flow velocity. Based on the Manning-Strickler equation, a simple algorithm to model temporally and spatially variable flow velocity was developed with the objective of improving flow routing in the global hydrological model of Water- GAP. An extensive data set of flow velocity measurements in US rivers was used to test and to validate the algorithm before integrating it into WaterGAP. In this test, flow velocity was calculated based on measured discharge and compared to measured velocity. Results show that flow velocity can be modeled satisfactorily at selected river cross sections. It turned out that it is quite sensitive to river roughness, and the results can be optimized by tuning this parameter. After the validation of the approach, the tested flow velocity algorithm has been implemented into the WaterGAP model. A final validation of its effects on the model results is currently performed.
Scientific results of the trawling expedition of H.M.C.S. "Thetis" : Crustacea, Part V., Amphipoda
(1910)
Prodromus florae Timorensis
(1841)
Optischer Raumsinn
(1913)
Nachstehend folgt mit Beschreibung der neuen Arten eine Zusammenstellung aller vom herrn EDM. KOVÁCS für das Ungarische National-Museum in den Jahren 1911 und 1912 in Abessynien gesammelten Chloropiden, die in ihrer Gesammtheit geeignet sind, ein Bild von der Reichhaltigkeit der dortigen Fauna zu geben. ...