Thermal dilepton and open charm signals versus hard initial yields in heavy-ion collisions at RHIC and LHC energies

The hard initial production of open charm and dileptons is compared with possible thermal signals in heavy-ion collisions at RHIC and LHC energies. Our approach is based on the perturbative QCD mini-jet mechanism of quark-gluon matter formation. The thermal dilepton signal is found to rise much stronger as compared to the hard Drell - Yan background with increasing collider energy and clearly dominates at LHC energy. Oppositely, open charm stems from initial hard production. A possible rnanifestation of gluon shadowing at RHIC and LHC energies is discussed

Allene und Heteroallene als Substrate zinkvermittelter, biomimetischer Additionsreaktionen

Die vorliegende Dissertation beschreibt die systematische Übertragung der biochemischen Prinzipien der Reaktion des Enzyms Carboanhydrase (CA) auf rein chemische Fragestellungen. CAs katalysieren die reversible Hydratisierung von Kohlendioxid und besitzen enorme Bedeutung bei unterschiedlichsten biochemischen Prozessen in jedem Organismus. Nicht zuletzt aufgrund ihres evolutionsbiologischen Alters gehören CAs zu den Enzymen mit den höchsten Wechselzahlen und Beschleunigungsfaktoren. Mittels geeigneter Modelle für experimentelle Umsetzungen und quantenchemische Berechnungen konnten die Reaktionsmechanismen von Allen und den Heteroallenen Carbodiimid, Keten, Ketenimin und Thioketen an biomimetischen Zinkkomplexen aufgeklärt werden. Die Berechnungen dieser Arbeit zeigen u.a., dass nicht Cyanamid, sondern das Isomer Carbodiimid das aktive Substrat der mechanismusgestützten Inhibition von CA darstellt. Auch Keten, Ketenimin und Thioketen können als Inhibitoren für CA wirken, da analog zu der Umsetzung mit Carbodiimid freie Carbonylgruppen zu einer hohen thermodynamischen Stabilität der Intermediate führen. Intensiv wurde die biomimetische Hydratisierung von Allen untersucht. Die durch kostengünstige Zinkkatalysatoren vermittelte Reaktion mit Nukleophilen erscheint als durchaus realisierbar und besitzt demzufolge einen deutlichen ökonomischen Aspekt. Die Ergebnisse aus der Berechnung der Aktivierungsbarrieren der Modellreaktion mit Wasser zeigen einen starken katalytischen Effekt, der sich durch geeignete Substitutionen verstärken lässt

Photon production in an expanding gluon-enriched plasma

Photon production in an expanding gluon plasma with initially little quark admixture is considered. Photons are created by lowest order a, processes which include quarks. Chemical equilibration of the quarks in turn is followed by rate equations which rely on lowest order αsgg = qq processes. Expansion slows down the quark cooking. Compared with the standard local equilibrium estimates we find a drastic reduction of mediumenergy photons if the initial quark admixure is below 20% of the chemical saturation density. Higher initial temperatures increase significantly the high-energy photon yield and overcompensate this reduction

Phonon-pump XUV-photoemission-probe in graphene: evidence for non-adiabatic heating of Dirac carriers by lattice deformation

We modulate the atomic structure of bilayer graphene by driving its lattice at resonance with the in-plane E1u lattice vibration at 6.3um. Using time- and angle-resolved photoemission spectroscopy (tr-ARPES) with extreme ultra-violet (XUV) pulses, we measure the response of the Dirac electrons near the K-point. We observe that lattice modulation causes anomalous carrier dynamics, with the Dirac electrons reaching lower peak temperatures and relaxing at faster rate compared to when the excitation is applied away from the phonon resonance or in monolayer samples. Frozen phonon calculations predict dramatic band structure changes when the E1u vibration is driven, which we use to explain the anomalous dynamics observed in the experiment.Comment: 16 pages, 8 figure

Differentiation between Parkinson disease and other forms of Parkinsonism using support vector machine analysis of susceptibility-weighted imaging (SWI): initial results

Objectives: To diagnose Parkinson disease (PD) at the individual level using pattern recognition of brain susceptibility-weighted imaging (SWI). Methods: We analysed brain SWI in 36 consecutive patients with Parkinsonism suggestive of PD who had (1) SWI at 3T, (2) brain 123I-ioflupane SPECT and (3) extensive neurological testing including follow-up (16 PD, 67.4 ± 6.2years, 11 female; 20 OTHER, a heterogeneous group of atypical Parkinsonism syndromes 65.2 ± 12.5years, 6 female). Analysis included group-level comparison of SWI values and individual-level support vector machine (SVM) analysis. Results: At the group level, simple visual analysis yielded no differences between groups. However, the group-level analyses demonstrated increased SWI in the bilateral thalamus and left substantia nigra in PD patients versus other Parkinsonism. The inverse comparison yielded no supra-threshold clusters. At the individual level, SVM correctly classified PD patients with an accuracy above 86%. Conclusions: SVM pattern recognition of SWI data provides accurate discrimination of PD among patients with various forms of Parkinsonism at an individual level, despite the absence of visually detectable alterations. This pilot study warrants further confirmation in a larger cohort of PD patients and with different MR machines and MR parameters. Key Points: • Magnetic resonance imaging data offers new insights into Parkinson's disease • Visual susceptibility-weighted imaging (SWI) analysis could not discriminate idiopathic from atypical PD • However, support vector machine (SVM) analysis provided highly accurate detection of idiopathic PD • SVM analysis may contribute to the clinical diagnosis of individual PD patients • Such information can be readily obtained from routine MR dat

New Constraints on the Slate Islands Impact Structure, Ontario, Canada

The Slate Islands in northern Lake Superior represent the eroded remains of a complex impact crater, originally approximately 32 km in diameter. New field studies there reveal allogenic crater fill deposits along the eastern and northern portions of the islands indicating that this 500-800 Ma impact structure is not as heavily eroded as previously thought. Near the crater center, on the western side or Patterson Island, massive blocks of target rocks, enclosed within a matrix of fine-grained polymict breccia, record the extensive deformation associated with the central uplift. Shatter cones are a common structural feature on the islands and range from less than 3 cm to over 10 m in length. Although shatter cones are powerful tools for recognizing and analyzing eroded impact craters, their origin remains poorly constrained