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Search Results: 1 - 10 of 401219 matches for " M. Armbruster "
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Redescription of Pterygoplichthys punctatus and description of a new species of Pterygoplichthys (Siluriformes: Loricariidae)
Armbruster, Jonathan W.;Page, Lawrence M.;
Neotropical Ichthyology , 2006, DOI: 10.1590/S1679-62252006000400003
Abstract: pterygoplichthys punctatus and p. weberi, new species, are unique among hypostomines in having a medially divided buccal papilla. the two species can be separated from one another by color (small spots in p. punctatus, large in p. weberi), condition of the buccal papilla (deeply divided at all ages in p. punctatus vs. shallowly divided in adults of p. weberi), condition of the lateral keel odontodes (fairly short and directed posteriorly in p. punctatus vs. large and directed almost laterally in p. weberi), and body width (sl/cleithral width 3.6-4.0 in p. punctatus vs. 3.3-3.4 in p. weberi). pterygoplichthys punctatus is known from the rio madeira drainage and the rio urubu of brazil and has published, but unconfirmed localities in the rio purus and rio tocantins basin, and p. weberi is known from the río mara?on, río ucayali, and upper río amazonas drainages of colombia, ecuador, and peru.
Modelling sulphate stream concentrations in the Black Forest catchments Schluchsee and Villingen
A. Prechtel,M. Armbruster,E. Matzner
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2003,
Abstract: The sulphate (SO4) released by mineralisation and desorption from soil can play an important role in determining concentrations of SO4 in streams. The MAGIC model was calibrated for two catchments in the Black Forest, Germany (Schluchsee and Villingen) and SO4 concentrations in the streams for the years 2016 and 2030 were predicted. Special emphasis was placed on the dynamics of soil sulphur (S) pools. At Schluchsee, 90% of soil S is stored in the organic S (Sorg) pool, whereas at Villingen, 54% is in the inorganic (Sinorg) pool. The Villingen stream chemistry was modelled successfully by measured Langmuir isotherm parameters (LIPs) for Sinorg. Schluchsee data could not be modelled satisfactorily using measured or freely adapted LIPs only, as the Sinorg pool would have to be more than five times larger than what was measured. With 60.5 mmolc SO4 m-2 yr-1 as internal soil source by mineralisation and the measured LIPs, stream data was modelled successfully. The modelling shows that in these two catchments pre-industrial concentrations of SO4 in runoff can be reached in the next two decades if S deposition decreases as intended under currently agreed national and international legislation. Sorg is the most likely dominant source of SO4 released at Schluchsee. Mineralization from the Sorg pool must be included when modelling SO4 concentrations in the stream. As the dynamics and the controlling factors of S release by mineralisation are not yet clear, this process remains a source of uncertainty for predictions of SO4 concentrations in streams. Future research should concentrate on dynamics of S mineralisation in the field, such that mathematical descriptions of long-term S-mineralisation can be incorporated into biogeochemical models. Keywords: sulphate release, organic S, mineralisation, acidification, recovery, modelling, MAGIC, catchments, predictions, Germany, forest
Are there signs of acidification reversal in freshwaters of the low mountain ranges in Germany?
C. Alewell,M. Armbruster,J. Bittersohl,C. D. Evans
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2001,
Abstract: The reversal of freshwater acidification in the low mountain ranges of Germany is of public, political and scientific concern, because these regions are near natural ecosystems and function as an important drinking water supply. The aim of this study was to evaluate the status and trends of acidification reversal after two decades of reduced anthropogenic deposition in selected freshwaters of the low mountain ranges in the Harz, the Fichtelgebirge, the Bavarian Forest, the Spessart and the Black Forest. In response to decreased sulphate deposition, seven out of nine streams investigated had significantly decreasing sulphate concentrations (all trends were calculated with the Seasonal Kendall Test). The decrease in sulphate concentration was only minor, however, due to the release of previously stored soil sulphur. No increase was found in pH and acid neutralising capacity (defined by Reuss and Johnson, 1986). Aluminum concentrations in the streams did not decrease. Thus, no major acidification reversal can currently be noted in spite of two decades of decreased acid deposition. Nevertheless, the first signs of improvement in water quality were detected as there was a decrease in the level and frequency of extreme values of pH, acid neutralising capacity and aluminium concentrations in streams. With respect to nitrogen, no change was determined for either nitrate or ammonium concentrations in precipitation or stream water. Base cation fluxes indicate increasing net loss of base cations from all ecosystems investigated, which could be interpreted as an increase in soil acidification. The latter was due to a combination of continued high anion leaching and significant reduction of base cation deposition. No major improvement was noted in biological recovery, however, initial signs of recovery were detectable as there was re-occurrence of some single macroinvertebrate species which were formerly extinct. The results of this study have important implications for water authorities, forest managers and policy makers: the delay in acidification reversal suggests a need for ongoing intensive amelioration of waters, a careful selection of management tools to guarantee sustainable management of forests and the reduction of nitrogen deposition to prevent further acidification of soils and waters. Keywords: freshwater, acidification reversal, drinking water supply, forested catchments, Germany
Response of sulphur dynamics in European catchments to decreasing sulphate deposition
A. Prechtel,C. Alewell,M. Armbruster,J. Bittersohl
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2001,
Abstract: Following the decline in sulphur deposition in Europe, sulphate dynamics of catchments and the reversibility of anthropogenic acidification of soils and freshwaters became of major interest. Long-term trends in sulphate concentrations and fluxes in precipitation/throughfall and freshwaters of 20 European catchments were analysed to evaluate catchment response to decreasing sulphate deposition. Sulphate deposition in the catchments studied declined by 38-82% during the last decade. Sulphate concentrations in all freshwaters decreased significantly, but acidification reversal was clearly delayed in the German streams. In Scandinavian streams and Czech/Slovakian lakes sulphate concentrations responded quickly to decreased input. Sulphate fluxes in run-off showed no clear trend in Germany and Italy but decreased in Scandinavia, the Czech Republic and Slovakia. The decrease, however, was less than the decline in input fluxes. While long-term sulphate output fluxes from catchments were generally correlated to input fluxes, most catchments started a net release of sulphate during the early 1990s. Release of stored sulphate leads to a delay of acidification reversal and can be caused by four major processes. Desorption and excess mineralisation were regarded as the most important for the catchments investigated, while oxidation and weathering were of lesser importance for the long-term release of sulphate. Input from weathering has to be considered for the Italian catchments. Sulphate fluxes in German catchments, with deeply weathered soils and high soil storage capacity, responded more slowly to decreased deposition than catchments in Scandinavia and the Czech Republic/Slovakia, which have thin soils and relatively small sulphate storage. For predictions of acidification reversal, soil characteristics, sulphur pools and their dynamics have to be evaluated in future research. Keywords: acidification reversal, sulphur, sulphate release, Europe, catchments, deposition, lake, stream
A model for consecutive spallation and fragmentation reactions in inverse kinematics at relativistic energies
P. Napolitani,L. Tassan-Got,P. Armbruster,M. Bernas
Physics , 2003, DOI: 10.1016/j.nuclphysa.2003.07.001
Abstract: Secondary reactions induced by relativistic beams in inverse kinematics in a thick target are relevant in several fields of experimental physics and technology, like secondary radioactive beams, production of exotic nuclei close to the proton drip line, and cross-section measurements for applications of spallation reactions for energy production and incineration of nuclear wastes. A general mathematical formulation is presented and successively applied as a tool to disentangle the primary reaction yields from the secondary production in the measurement of fission of a 238U projectile impinging on a proton target at the energy of 1 A GeV.
Bounds for the expected value of one-step processes
Benjamin Armbruster,ádám Besenyei,Péter L. Simon
Computer Science , 2015,
Abstract: Mean-field models are often used to approximate Markov processes with large state-spaces. One-step processes, also known as birth-death processes, are an important class of such processes and are processes with state space $\{0,1,\ldots,N\}$ and where each transition is of size one. We derive explicit bounds on the expected value of such a process, bracketing it between the mean-field model and another simple ODE. Our bounds require that the Markov transition rates are density dependent polynomials that satisfy a sign condition. We illustrate the tightness of our bounds on the SIS epidemic process and the voter model.
Die Behandlung Adolf Hitlers im Lazarett Pasewalk 1918: Historische Mythenbildung durch einseitige bzw. spekulative Pathographie
Armbruster J
Journal für Neurologie, Neurochirurgie und Psychiatrie , 2009,
Abstract: Das Interesse an der Person Adolf Hitlers (1889 1945) scheint auch über 60 Jahre nach seinem Tod ungebrochen. Im Zuge dessen finden sich unter pathographischen Betrachtungen auch Tendenzen, Fragmente aus dem Kontext der Gesamtbiographie herauszul sen, in ihrer Bedeutung zu überh hen und unter Vernachl ssigung der Komplexit t historischer Strukturen und Prozesse zu deuten. Dies l sst sich beispielhaft an einer Reihe von Arbeiten zeigen, die sich u. a. der Behandlung einer Kriegsverletzung Hitlers 1918 im Reservelazarett Pasewalk widmen und mit spekulativen Thesen einen Status historischer Authentizit t beanspruchen. W hrend in Bezug auf Hitlers Gesundheitszustand ein Teil überlieferter somatischer Befunde gewisse Rückschlüsse zul sst, fehlen solche Dokumente im Hinblick auf seinen psychischen Zustand. In den vergangenen Jahren rückte der Psychiater Edmund Robert Forster (1878 1933) zunehmend in den Fokus des Interesses. Auf Grundlage eines Berichtes des US-Marine-Geheimdienstes aus dem Jahre 1943 wurde die These entwickelt, dass Forster Hitler behandelt habe und sich vornehmlich aufgrund dessen 1933 suizidierte. Einige Arbeiten bauen unter Ausblendung alternativer M glichkeiten diese Theorie auf Grundlage der Romanvorlage Der Augenzeuge von Ernst Wei (1882 1940) bis zu einer vermeintlich gesicherten Hypnosetherapie Hitlers durch Forster aus. Die Stilisierung Forsters zum Sch pfer Hitlers kann angesichts des Aufgreifens durch die Medien als Beispiel für die Entwicklung eines Mythos herangezogen werden. Der Tragik des Schicksals Forsters wird auf diese Weise wenig Rechnung getragen. Gleichzeitig birgt dies die Gefahr, dass Hitler zu einem Teil von seiner Verantwortung entbunden wird. Insofern sollte eine Diagnostik ex post überhaupt nur mit gr ter Zurückhaltung erfolgen.
A region of oblate nuclides centred at Z = 114 and of spherical nuclides centred at the magic nucleus - A possible scenario to understand the production of superheavy elements beyond copernicium
Armbruster P.
EPJ Web of Conferences , 2011, DOI: 10.1051/epjconf/20111712001
Abstract: The recent experiments at FLNR, Dubna, demonstrated that cross sections to produce SHEs by 48Ca induced reactions on actinide targets increase beyond Z = 111, reach a maximum of 5 pb at Z = 114/115, and fall below the 1 pb-level at Z = 118. A scenario is proposed to understand the ndings within the frame of former experimental results of heavy element production and theoretical predictions on the stability of the nuclides concerned. New ingredients introduced are 1) to shift the next proton shell beyond Pb from Z = 114 to Z = 122, 2) the isotopes of elements Z = 112 to Z = 118 are deformed and their nuclei have oblate shapes, and 3) the ssion barriers around the next magic nucleus 306122184 are larger than the neutron separation energies and reach values in the range of 10 MeV. The ascent of the at top at 306122184 is described by the proposed scenario, which likewise excludes to reach the doubly closed shell region at the top by today s experimental methods in complete fusion reactions.
The loricariid catfish genus Lasiancistrus (Siluriformes) with descriptions of two new species
Armbruster, Jonathan W.;
Neotropical Ichthyology , 2005, DOI: 10.1590/S1679-62252005000400013
Abstract: lasiancistrus (loricariidae: hypostominae: ancistrini) is diagnosed by the unique presence of a ventral strut of the pterotic and the presence of whiskerlike odontodes on the snout. lasiancistrus has about 16 species assigned to it; however, only four are valid (l. schomburgkii, l. caucanus, l. guacharote, and l. heteracanthus), l. nationi is an ancistrus, and l. trinitatus is incertae sedis in the loricariidae. lasiancistrus maracaiboensis and l. mystacinus are synonyms of l. guacharote; l. pictus, l. castelnaui, l. caquetae, l. guapore, l. multispinis, and l. scolymus are synonyms of l. schomburgkii; and l. planiceps, l. mayoloi, and l. volcanensis are synonyms of l. caucanus. two new species are described: l. tentaculatus from the río orinoco basin and l. saetiger from the rio guama. the species can largely be told apart via color (l. schomburgkii has no or white spots on the fins, l. saetiger has entirely gray fins, and the rest have black spots in the fins), the presence of abdominal plates (l. caucanus, l. saetiger, and l. tentaculatus have naked abdomens, l. guacharote has a few small plates near the insertion of the pectoral fin, l. heteracanthus has a large patch of small plates, and l. schomburgkii is variable), and nuptial male condition (l. tentaculatus has small tentacles along the edge of the snout and the other species have a patch of whisker-like odontodes at the corners of the snout). most species are widespread in piedmont regions of south america with l. schomburgkii occurring in the amazon, orinoco, and essequibo basins.
Technological change and interaction between the Atlantic and the Mediterranean: ''El Carambolo'' hoard, Seville
Perea, Alicia,Armbruster, Barbara
Trabajos de Prehistoria , 1998,
Abstract: The concept of technological domain systems is the theoretical construct that we have applied to put forward an explanation for this goldhoard. We start with a technological study based on the topographical observation of working traces and manufacture procedures, and we end suggesting a model aiming at explaining technogical and social change at the end of Final Bronze Age and the begining of the orientalizing period, when two different socities coexist in the south of the Iberian Peninsula. Hemos empleado la teoría de los ámbitos tecnológicos para proponer una explicación de este depósito de oro. Comenzamos con el análisis tecnológico, basado en la observación topográfica de las huellas de trabajado y procesos de fabricación, para finalizar con un modelo sobre el cambio tecnológico y social que se produce a fines de la Edad del Bronce y principios del periodo orientalizante, cuando dos sociedades distintas conviven en el sur peninsular.
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