Räumliche Variabilität und zeitliche Trends des Trockenstressrisikos von Kiefernstandorten in Mecklenburg-Vorpommern

Die Bodenwasserverfügbarkeit bestimmt zu einem hohen Maße die Vitalität von Bäumen und Waldstandorten. In einigen Teilen Euro-pas wurde in den letzten Jahrzehnten eine häufigere Anzahl von Trockenperioden beobachtet, die bereits das Baumwachstum negativ beeinflusst haben. Es wurden langfristige Trends von Bodentrockenheit unter Kiefernstandorten entlang des klimatischen Gradienten in Mecklenburg-Vorpommern mit dem physikalisch basierten Modell LWF-BROOK90 untersucht. Die Ergebnisse zeigen eine zunehmende Anzahl von Trockenstresstagen ostwärts mit abnehmenden Niederschlagssummen. Die klimatischen Unterschiede innerhalb des Landes werden teilweise von den spezifischen Standortbedingungen und Bodeneigenschaften überprägt. Bodentrockenheit hat in den letzten Jahrzehnten deutlich zugenommen, wobei die östlichen Standorte stärker als die westlichen betroffen sind. Die zunehmende Bodentrockenheit konnte auf einen erhöhten Verdunstungsanspruch der Atmosphäre zurückgeführt werden aufgrund höherer Temperaturen in Kombination mit leicht abnehmenden Niederschlägen während der Sommermonate. Um die negativen Auswirkungen künftiger klimatischer Änderungen zu minimieren, sollten Anpassungsmaßnahmen vorzugsweise im Osten des Landes durchgeführt werden

Jets and energy flow in photon-proton collisions at HERA

Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to \overline{p}p data and QCD calculations. The comparisons show that the \gamma p events can be consistently described by QCD models including -- in addition to the primary hard scattering process -- interactions between the two beam remnants. The differential jet cross sections d\sigma/dE_T^{jet} and d\sigma/d\eta^{jet} are measured

Разработка интерактивной моделирующей системы технологии низкотемпературной сепарации газа

We present a study of J ψ meson production in collisions of 26.7 GeV electrons with 820 GeV protons, performed with the H1-detector at the HERA collider at DESY. The J ψ mesons are detected via their leptonic decays both to electrons and muons. Requiring exactly two particles in the detector, a cross section of σ(ep → J ψ X) = (8.8±2.0±2.2) nb is determined for 30 GeV ≤ W γp ≤ 180 GeV and Q 2 ≲ 4 GeV 2 . Using the flux of quasi-real photons with Q 2 ≲ 4 GeV 2 , a total production cross section of σ ( γp → J / ψX ) = (56±13±14) nb is derived at an average W γp =90 GeV. The distribution of the squared momentum transfer t from the proton to the J ψ can be fitted using an exponential exp(− b ∥ t ∥) below a ∥ t ∥ of 0.75 GeV 2 yielding a slope parameter of b = (4.7±1.9) GeV −2

Evidence for the τ→\tau\to Neutrino ρπ\rho\pi decay mode

Annihilation of e + e − into final states with a single electron has been studied with the PLUTO detector at the DORIS storage ring at CMS energies from 3.6 to 5 GeV. In the sample of 4-prong events without any detected photon we observe 21 events which we assign to the reaction e + e − → τ + τ − → νν e + νϱ 0 π . We obtain a branching ratio for τ + → νϱ 0 π + of 0.050 ± 0.015 with an overall systematic uncertainty of 30%. The data are consistent with the ϱπ coming from an A 1 meson

Studies of multihadronic final states in photon-photon interactions

We have measured the cross section and $Q^2$-dependence of the reaction γγ→ multihadrons, using the CELLO detector at DESY, for visible final-state masses between 4 and 9 GeV. The data are well fitted by an incoherent sum of Generalised Vector Meson Dominance and Quark Parton Model terms, but at lowQ2 require the addition of a third component which resembles the QPM but is less two-jet-like. With and without this term, the GVDM cross section atQ2=0 is found to be 200±20 and 250±25 nb, respectively

Studies of multihadronic final states in photon-photon interactions

We have measured the cross section and $Q^2$-dependence of the reaction γγ→ multihadrons, using the CELLO detector at DESY, for visible final-state masses between 4 and 9 GeV. The data are well fitted by an incoherent sum of Generalised Vector Meson Dominance and Quark Parton Model terms, but at lowQ2 require the addition of a third component which resembles the QPM but is less two-jet-like. With and without this term, the GVDM cross section atQ2=0 is found to be 200±20 and 250±25 nb, respectively