166 research outputs found
"Einer von drei SozialpĂ€dagogen arbeitet nach dem Studium mit alten Menschen" : Alternswissenschaft ist fĂŒr eine zukunftsorientierte UniversitĂ€t essenziell ; im GesprĂ€ch: Prof. Dr. Gisela Zenz und Prof. Dr. GĂŒnther Böhme mit Ulrike Jaspers und Anne Hardy
Als Sie vor ĂŒber drei Jahren das Forum »Alterswissenschaften und Alterspolitik« ins Leben gerufen haben, wollten Sie eine fĂ€cherĂŒbergreifende Zusammenarbeit in der Altersforschung initiieren. Was ist daraus geworden? Zenz: Wir haben zunĂ€chst einmal mit der öffentlichen Vorstellung von Frankfurter Forschungsprojekten begonnen. Im Rahmen einer Vortragsreihe sind immer wieder Wissenschaftler aus unterschiedlichen Disziplinen zusammengekommen â aus Sportwissenschaft und Psychologie, Biologie und Hirnforschung, Ăkonomie und Soziologie, Psychiatrie und PĂ€dagogik. Dabei sind auch Fachhochschul- und Praxisprojekte einbezogen worden, um Beispiel vom Frankfurter BĂŒrgerinstitut. Und immer haben wir Wert darauf gelegt, dass neben den etablierten Professoren der »wissenschaftliche Nachwuchs« zu Wort kam. ..
Three soil bacterial communities from an archaeological excavation site of an ancient coal mine near Bennstedt (Germany) characterized by 16S r-RNA sequencing
This metagenomics investigation of three closely adjacent sampling sites from an archaeological excavation of a pre-industrial coal mining exploration shaft provides detailed information on the composition of the local soil bacterial communities. The observed significant differences between the samples, reflected in the 16S r-RNA analyses, were consistent with the archaeologically observed situation distinguishing the coal seam, the rapidly deposited bright sediment inside an exploration shaft, and the topsoil sediment. In general, the soils were characterized by a dominance of Proteobacteria , Actinobacteria , Acidobacteria , and Archaea , whereas the coal seam was characterized by the highest proportion of Proteobacteria ; the topsoil was characterized by very high proportions of Archaea âin particular, Nitrosotaleaceae âand Acidobacteria, mainly of Subgroup 2. Interestingly, the samples of the fast-deposited bright sediment showed a rank function of OTU abundances with disproportional values in the lower abundance range. This could be interpreted as a reflection of the rapid redeposition of soil material during the refilling of the exploration shaft in the composition of the soil bacterial community. This interpretation is supported by the observation of a comparatively high proportion of reads relating to bacteria known to be alkaliphilic in this soil material. In summary, these investigations confirm that metagenomic analyses of soil material from archaeological excavations can provide valuable information about the local soil bacterial communities and the historical human impacts on them
Measurement of triple gauge boson couplings from WâșWâ» production at LEP energies up to 189 GeV
A measurement of triple gauge boson couplings is presented, based on W-pair data recorded by the OPAL detector at LEP during 1998 at a centre-of-mass energy of 189 GeV with an integrated luminosity of 183 pbâ»Âč. After combining with our previous measurements at centre-of-mass energies of 161â183 GeV we obtain Îș = 0.97_{-0.16}^{+0.20}, g_{1}^{z} = 0.991_{-0.057}^{+0.060} and λ = -0.110_{-0.055}^{+0.058}, where the errors include both statistical and systematic uncertainties and each coupling is determined by setting the other two couplings to their Standard Model values. These results are consistent with the Standard Model expectations
A measurement of the tau mass and the first CPT test with tau leptons
We measure the mass of the tau lepton to be 1775.1+-1.6(stat)+-1.0(syst.) MeV
using tau pairs from Z0 decays. To test CPT invariance we compare the masses of
the positively and negatively charged tau leptons. The relative mass difference
is found to be smaller than 3.0 10^-3 at the 90% confidence level.Comment: 10 pages, 4 figures, Submitted to Phys. Letts.
Measurement of the B0 Lifetime and Oscillation Frequency using B0->D*+l-v decays
The lifetime and oscillation frequency of the B0 meson has been measured
using B0->D*+l-v decays recorded on the Z0 peak with the OPAL detector at LEP.
The D*+ -> D0pi+ decays were reconstructed using an inclusive technique and the
production flavour of the B0 mesons was determined using a combination of tags
from the rest of the event. The results t_B0 = 1.541 +- 0.028 +- 0.023 ps, Dm_d
= 0.497 +- 0.024 +- 0.025 ps-1 were obtained, where in each case the first
error is statistical and the second systematic.Comment: 17 pages, 4 figures, submitted to Phys. Lett.
WW Production Cross Section and W Branching Fractions in e+e- Collisions at 189 GeV
From a data sample of 183 pb^-1 recorded at a center-of-mass energy of roots
= 189 GeV with the OPAL detector at LEP, 3068 W-pair candidate events are
selected. Assuming Standard Model W boson decay branching fractions, the W-pair
production cross section is measured to be sigmaWW = 16.30 +- 0.34(stat.) +-
0.18(syst.) pb. When combined with previous OPAL measurements, the W boson
branching fraction to hadrons is determined to be 68.32 +- 0.61(stat.) +-
0.28(syst.) % assuming lepton universality. These results are consistent with
Standard Model expectations.Comment: 22 pages, 5 figures, submitted to Phys. Lett.
Genuine Correlations of Like-Sign Particles in Hadronic Z0 Decays
Correlations among hadrons with the same electric charge produced in Z0
decays are studied using the high statistics data collected from 1991 through
1995 with the OPAL detector at LEP. Normalized factorial cumulants up to fourth
order are used to measure genuine particle correlations as a function of the
size of phase space domains in rapidity, azimuthal angle and transverse
momentum. Both all-charge and like-sign particle combinations show strong
positive genuine correlations. One-dimensional cumulants initially increase
rapidly with decreasing size of the phase space cells but saturate quickly. In
contrast, cumulants in two- and three-dimensional domains continue to increase.
The strong rise of the cumulants for all-charge multiplets is increasingly
driven by that of like-sign multiplets. This points to the likely influence of
Bose-Einstein correlations. Some of the recently proposed algorithms to
simulate Bose-Einstein effects, implemented in the Monte Carlo model PYTHIA,
are found to reproduce reasonably well the measured second- and higher-order
correlations between particles with the same charge as well as those in
all-charge particle multiplets.Comment: 26 pages, 6 figures, Submitted to Phys. Lett.
Vicariance and dispersal in southern hemisphere freshwater fish clades: a palaeontological perspective
Widespread fish clades that occur mainly or exclusively in fresh water represent a key target of biogeographical investigation due to limited potential for crossing marine barriers. Timescales for the origin and diversification of these groups are crucial tests of vicariant scenarios in which continental breakâups shaped modern geographic distributions. Evolutionary chronologies are commonly estimated through nodeâbased palaeontological calibration of molecular phylogenies, but this approach ignores most of the temporal information encoded in the known fossil record of a given taxon. Here, we review the fossil record of freshwater fish clades with a distribution encompassing disjunct landmasses in the southern hemisphere. Palaeontologically derived temporal and geographic data were used to infer the plausible biogeographic processes that shaped the distribution of these clades. For seven extant clades with a relatively wellâknown fossil record, we used the stratigraphic distribution of their fossils to estimate confidence intervals on their times of origin. To do this, we employed a Bayesian framework that considers nonâuniform preservation potential of freshwater fish fossils through time, as well as uncertainty in the absolute age of fossil horizons. We provide the following estimates for the origin times of these clades: Lepidosireniformes [125â95Â million years ago (Ma)]; totalâgroup Osteoglossomorpha (207â167Â Ma); Characiformes (120â95Â Ma; a younger estimate of 97â75Â Ma when controversial Cenomanian fossils are excluded); Galaxiidae (235â21Â Ma); Cyprinodontiformes (80â67Â Ma); Channidae (79â43Â Ma); Percichthyidae (127â69Â Ma). These dates are mostly congruent with published molecular timetree estimates, despite the use of semiâindependent data. Our reassessment of the biogeographic history of southern hemisphere freshwater fishes shows that longâdistance dispersals and regional extinctions can confound and erode preâexisting vicarianceâdriven patterns. It is probable that disjunct distributions in many extant groups result from complex biogeographic processes that took place during the Late Cretaceous and Cenozoic. Although longâdistance dispersals likely shaped the distributions of several freshwater fish clades, their exact mechanisms and their impact on broader macroevolutionary and ecological dynamics are still unclear and require further investigation.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148368/1/brv12473_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148368/2/brv12473.pd
Determination of nutrient salts by automatic methods both in seawater and brackish water: the phosphate blank
9 pĂĄginas, 2 tablas, 2 figurasThe main inconvenience in determining nutrients in seawater by automatic methods is simply solved:
the preparation of a suitable blank which corrects the effect of the refractive index change on the recorded
signal. Two procedures are proposed, one physical (a simple equation to estimate the effect) and the other
chemical (removal of the dissolved phosphorus with ferric hydroxide).Support for this work came from CICYT (MAR88-0245 project) and
Conselleria de Pesca de la Xunta de GaliciaPeer reviewe
Search for Leptoquarks in Electron-Photon Scattering at sqrt(s_ee) up to 209 GeV at LEP
Searches for first generation scalar and vector leptoquarks, and for squarks
in R-parity violating SUSY models with the direct decay of the squark into
Standard Model particles, have been performed using e+e- collisions collected
with the OPAL detector at LEP at e+e- centre-of-mass energies between 189 and
209 GeV. No excess of events is found over the expectation from Standard Model
background processes. Limits are computed on the leptoquark couplings for
different values of the branching ratio to electron-quark final states.Comment: 23 pages, 5 figures, Submitted to Phys. Lett.
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