Hadronization of Dense Partonic Matter

The parton recombination model has turned out to be a valuable tool to describe hadronization in high energy heavy ion collisions. I review the model and revisit recent progress in our understanding of hadron correlations. I also discuss higher Fock states in the hadrons, possible violations of the elliptic flow scaling and recombination effects in more dilute systems.Comment: 8 pages, 4 figures; plenary talk delivered at SQM 2006, to appear in J. Phys.

Motor recovery following capsular stroke

The functional anatomy of motor recovery was studied by assessing motor function quantitatively in 23 patients following capsular or striatocapsular stroke. While selective basal ganglia lesions (caudate and/or putamen exclusively) did not affect voluntary movements of the extremities, lesions of the anterior (plus caudate/putamen) or posterior limb of the internal capsule led to an initially severe motor impairment followed by excellent recovery, hand function included. In contrast, lesions of the posterior limb of the internal capsule in combination with damage to lateral thalamus compromised motor outcome. In experimental tracing of the topography of the internal capsule in macaque monkeys, we found axons of primary motor cortex passing through the middle third of the posterior limb of the internal capsule. Axons of premotor cortex (dorsolateral and post-arcuate area 6) passed through the capsular genu, and those of supplementary motor area (mesial area 6) through the anterior limb. Small capsular lesion can therefore disrupt the output of functionally and anatomically distinct motor areas selectively. The clinically similar motor deficits with a similar course of functional restitution following disruption of these different descending motor pathways indicate a parallel operation of cortical motor areas. They may have the further capability of substituting each other functionally in the process of recovery from hemiparesis

High Momentum Dilepton Production from Jets in a Quark Gluon Plasma

We discuss the emission of high momentum lepton pairs in central Au+Au collisions at RHIC ($\sqrt{s_{NN}}=$200 GeV) and Pb+Pb collisions at the LHC ($\sqrt{s_{NN}}=$5500 GeV). Yields of dileptons produced through interactions of jets with thermal partons have been calculated, with next-to-leading order corrections through hard thermal loops (HTL) resummation. They are compared to thermal dilepton emission and the Drell-Yan process. A complete leading order treatment of jet energy loss has been included. Jet-plasma interactions are found to dominate over thermal dilepton emission for all values of the invariant mass $M$. Drell-Yan is the dominant source of high momentum lepton pairs for $M >$ 3 GeV at RHIC, after the background from heavy quark decays is subtracted. At LHC, the range $M<7$ GeV is dominated by jet-plasma interactions. Effects from jet energy loss on jet-plasma interactions turn out to be weak, but non-negligible, reducing the yield of low-mass dileptons by about 30%.Comment: 20 pages, 12 figures, discussions adde

Concentrations of higher dicarboxylic acids C5 – C13 in fresh snow samples collected at the High Alpine Research Station Jungfraujoch during CLACE 5 and 6

Samples of freshly fallen snow were collected at the high alpine research station Jungfraujoch (Switzerland) in February and March 2006 and 2007, during the Cloud and Aerosol Characterization Experiments (CLACE) 5 and 6. In this study a new technique has been developed and demonstrated for the measurement of organic acids in fresh snow. The melted snow samples were subjected to solid phase extraction and resulting solutions analysed for organic acids by HPLC-MS-TOF using negative electrospray ionization. A series of linear dicarboxylic acids from C5 to C13 and phthalic acid, were identified and quantified. In several samples the biogenic acid pinonic acid was also observed. In fresh snow the median concentration of the most abundant acid, adipic acid, was 0.69 micro g L -1 in 2006 and 0.70 micro g L -1 in 2007. Glutaric acid was the second most abundant dicarboxylic acid found with median values of 0.46 micro g L -1 in 2006 and 0.61 micro g L -1 in 2007, while the aromatic acid phthalic acid showed a median concentration of 0.34 micro g L -1 in 2006 and 0.45 micro g L -1 in 2007. The concentrations in the samples from various snowfall events varied significantly, and were found to be dependent on the back trajectory of the air mass arriving at Jungfraujoch. Air masses of marine origin showed the lowest concentrations of acids whereas the highest concentrations were measured when the air mass was strongly influenced by boundary layer air

Direct Characterization of Comets and Asteroids via Cosmic Dust Analysis from the Deep Space Gateway

The Deep Space Gateway (DSG) may provide a platform for direct sampling of a large number of comets and asteroids, through employment of an instrument for characterizing dust from these bodies. Every year, the Earth traverses through debris streams of dust and small particles from comets and asteroids in Earth-crossing orbits, generating short-lived outbursts of meteor activity commonly known as "meteor showers" (Figure 1). The material in each debris stream originates from a distinct parent body, many of which have been identified. By sampling this material, it is possible to quantitatively analyze the composition of a dozen or more comets and asteroids (See Figure 2, following page) without leaving cislunar space

Cooper-Frye Formula and Non-extensive Coalescence at RHIC Energy

Transverse spectra are calculated for various types of hadrons stemming from Au Au collisions at $\sqrt{s}=200$ GeV. We utilize a quark recombination model based on generalized Boltzmann-Gibbs thermodynamics for local hadron production at various break-up scenarios.Comment: 4 pages, 1 figur

Hadronization in heavy ion collisions: Recombination and fragmentation of partons

We argue that the emission of hadrons with transverse momentum up to about 5 GeV/c in central relativistic heavy ion collisions is dominated by recombination, rather than fragmentation of partons. This mechanism provides a natural explanation for the observed constant baryon-to-meson ratio of about one and the apparent lack of a nuclear suppression of the baryon yield in this momentum range. Fragmentation becomes dominant at higher transverse momentum, but the transition point is delayed by the energy loss of fast partons in dense matter.Comment: 4 pages, 2 figures; v2: reference [8] added; v3: Eq.(2) corrected, two references added, version to appear in PR

Photochromic organic-inorganic hybrid nanocomposite hard coatings with tailored fast switching properties

A recently developed photochromic organic-inorganic nanocomposite (Nanomer) coating system is investigated, which is based on an epoxysilane as network former, different bisepoxides as spacer and an organic amine as thermal cross-linker. This coating system is compatible with different photochromic dyes like oxazines, pyrans and fulgides and also with surface modified ceramic nanoparticles as filler in order to obtain macroscopic hard properties\u27 without changing the photochromic kinetics. In order to investigate the dye-spacer interactions and influence on the switching kinetic behavior, the matrix composition was diminished to the network former, the thermal cross-linker and two types (polar and nonpolar) of spacers in different concentrations. Four commercially available spirooxazines with different molecular sizes and polarities were incorporated into the matrices and coatings on glass slides were prepared by float-coating and cured at 130 °C for 2 h. The half darkening and half fading times of the coatings were measured by a fast diode array spectrometer as a function of spacer type and concentration for the four different dyes. The nonpolar\u27 spacer CHMG did not influence the switching kinetic of the dyes significantly and fast switching times of 2 s-4 s were obtained. The polar\u27 spacer PCF (aromatic character) showed interactions with the dye molecules, which led to an increase in the switching times of up to 25 s. The retardation of the switching process increased with increasing spacer content and with increasing polar character of the dye molecule. From these results, it could be concluded that the photochromic behavior of the spirooxazines could be adjusted to different applications by interactions with polar spacers