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  • 1
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A search has been made for new particles with chargeQ=2/3, 1, 4/3, 5/3 produced ine + e −-reactions at PETRA. The energy range wasE cm=27–35 GeV. No such particles were found. Upper limits for the cross-section depending on the assumed mass and production spectrum are given. ForQ=2/3 quarks with mass less than 12 GeV/c 2, upper limits $${{\sigma \left( {q\bar q} \right)} \mathord{\left/ {\vphantom {{\sigma \left( {q\bar q} \right)} {\sigma \left( {\mu \mu } \right)}}} \right. \kern-\nulldelimiterspace} {\sigma \left( {\mu \mu } \right)}} \leqq 10^{ - 2} $$ (90% C.L.) are obtained both for inclusive and exclusive production. For the lifetime of theB-meson (m B =5GeV/c 2) an upper limit τ≦2×10−9s is obtained.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Cross sections for the reactionse + e −→e + e − (Bhabha scattering) ande + e −→γγ are measured for center-of-mass (c.m.) energies $$\sqrt s $$ between 12.0 and 34.6 GeV. The results agree with the predictions of Quantum Electrodynamics (QED) and the cut-off parameters are determined. From Bhabha scattering at the highest energy, $$\left\langle {\sqrt s } \right\rangle = 34.6 GeV$$ , the 1 δ limits 0.12〈sin2 ϑ w 〈0.38 are obtained for the weak mixing angle. The higher order (α3) QED processese + e −→e + e −γ ande + e −→γγγ are also studied and are found to agree with the α3 QED predictions. A search for excited electrons is carried out by investigating the (e ±γ) invariant mass distribution in the reactione + e −→e + e −γ.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The mean charged multiplicity as well as its distribution has been measured as a function of c.m. energy in the reactione + e −→hadrons. Fragmentation models are compared with the data. After applying radiative corrections the mean charged multiplicity is measured to be 8.4±0.3±0.6 at 12 GeV, 13.1±0.3±0.6 at 30 GeV and 13.6±0.3±0.6 at 35 GeV. The ratio of mean charged multiplicity to the dispersion (〈N ch〉/D ch) is almost constant in the energy range studied, indicating KNO scaling of the charged multiplicity. The inclusive differential cross sections(dσ/dx p ) shows scaling violation in the highx p region (x p 〉0.15). The absolute value of the scaling violation is consistent with the result of 2nd order QCD calculations. The production of neutral kaons has been investigated by identifying the decayK S 0 →π+π−. The production probability for a strange quark relative to that of au ord quark in the fragmentation, γ s , has been determined to be 0.27±0.03±0.05 averaged over c.m. energies from 12 to 35 GeV. Momentum spectra for neutral kaons are presented and are compared with model predictions.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1459
    Keywords: Cerebrospinal fluid proteins (analysis) ; β2-microglobulin ; Bloodbrain barrier ; Cerebrospinal fluid (metabolism) ; Age factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Konzentration von γ-Trace und β2-Mikroglobulin wurde in Liquor und Plasma von 64 Personen unterschiedlichen Alters bestimmt, welche keine Zeichen einer organischen Störung des ZNS aufwiesen. Es zeigte sich ein enger Zusammenhang zwischen der Liquorkonzentration von γ-Trace und dem Alter der betreffenden Person, wobei Neugeborene einen 3–4fach höheren Wert als Erwachsene aufwiesen. Eine ähnliche, jedoch weniger ausgeprägte Altersabhängigkeit wurde für die Konzentration von β2-Mikroglobulin im Liquor festgestellt. Die Plasmakonzentration der beiden Proteine variierte ebenfalls je nach Alter der Person, die Schwankungen waren jedoch nicht so deutlich wie im Liquor. Diese Ergebnisse zeigen, daß es dringend erforderlich ist, für die Bestimmung der Proteine in Liquor und Plasma Kontrollwerte aus der betreffenden Altersgruppe zu verwenden. Zusätzlich wurden 13 Kinder und 98 Erwachsene mit neurologischen Erkrankungen untersucht. Signifikant erhöhte Liquorwerte von γ-Trace und β2-Mikroglobulin, eine erhöhte Plasmakonzentration von γ-Trace sowie ein erhöhter Liquor/Plasma-Gradient für β2-Mikroglobulin wurden bei Infektionskrankheiten gefunden. Bei cerebrovasculären Erkrankungen waren die γ-Trace-Konzentration im Plasma und der β2-Mikroglobulin-Wert im Liquor erhöht. Die Mechanismen der Proteinregulierung im Liquor werden diskutiert.
    Notes: Summary The concentrations of γ-trace and β2-microglobulin in cerebrospinal fluid (CSF) and plasma were determined in 64 individuals of various ages without signs of organic disorder in the central nervous system (CNS). A strong connection was found between the CSF level of γ-trace and the age of the individual, with the CSF level of newborns being 3–4 times that of adults. A similar, but less marked, connection was found for the CSF level of β2-microglobulin and the age of the individual. The plasma levels of the two proteins also varied with the age of the individual, but the variations were not as great as those of the CSF levels. The results strongly emphasize the necessity of using age-matched reference values when CSF and plasma levels of the proteins are to be evaluated in different groups of patients. thirteen children and 98 adults with various neurological disorders were also examined. Significantly increased CSF levels of γ-trace and β2-microglobulin as well as increased plasma concentration of γ-trace and CSF/plasma gradient of β2-microglobulin were found in infectious disorders. Increased γ-trace concentration in plasma and β2-microglobulin concentration in CSF were seen in cerebrovascular disorders. The mechanisms which regulate the turnover of proteins in CSF are discussed.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have studied the distribution of particles within and between jets of 3-jet final states produced in the reactione + e −→hadrons at c.m. energies of 22 GeV and 29–36.4 GeV. The lowest energy jet shows distributions of transverse momenta, particle flow, and energy flow which differ significantly from those of the other two jets and from jets of 2-jet events atE cm=14 GeV. First order QCD calculations with subsequent fragmentation of quarks and gluons into hadrons indicate that the lowest energy jet has the largest probability of originating from a gluon. To reproduce the observed differences in an independent parton fragmentation model, the secondary quarks of a gluon jet have to have higher transverse momenta and lower parallel momenta than those of a quark jet. The particle densities between the jets as well as the correlation of transverse and longitudinal momenta of the particles within the jets favour models with fragmentation along the colour axes.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Energy-energy-correlations (EEC) have been measured with the JADE detector at c.m. energies of 14 GeV, 22 GeV and in the region 29 GeV〈E cm〈36 GeV. Corrected results are presented of EEC and their asymmetry, which can be directly compared to theoretical predictions. At 〈E cm〉=34 GeV a comparison with second order QCD predictions yields good agreement for the string model fragmentation resulting in a value of the strong coupling constant α s =0.165±0.01 (stat.). The independent fragmentation models, which yield values of α s between 0.10 and 0.15 depending on the treatment of energy and momentum conservation and of the gluon splitting, do not provide a satisfactory description of the data over the full angular range.
    Type of Medium: Electronic Resource
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