Electromagnetic Probes

A review is presented of dilepton and real photon measurements in relativistic heavy ion collisions over a very broad energy range from the low energies of the BEVALAC up to the highest energies available at RHIC. The dileptons cover the invariant mass range \mll = 0 - 2.5 GeV/c$^2$, i.e. the continuum at low and intermediate masses and the light vector mesons, $\rho, \omega, \phi$. The review includes also measurements of the light vector mesons in elementary reactions.Comment: To be published in Landolt-Boernstein Volume 1-23A; 40 pages, 24 figures. Final version updated with small changes to the text, updated references and updated figure

Unsupervised Classification for Tiling Arrays: ChIP-chip and Transcriptome

Tiling arrays make possible a large scale exploration of the genome thanks to probes which cover the whole genome with very high density until 2 000 000 probes. Biological questions usually addressed are either the expression difference between two conditions or the detection of transcribed regions. In this work we propose to consider simultaneously both questions as an unsupervised classification problem by modeling the joint distribution of the two conditions. In contrast to previous methods, we account for all available information on the probes as well as biological knowledge like annotation and spatial dependence between probes. Since probes are not biologically relevant units we propose a classification rule for non-connected regions covered by several probes. Applications to transcriptomic and ChIP-chip data of Arabidopsis thaliana obtained with a NimbleGen tiling array highlight the importance of a precise modeling and the region classification

Affymetrix probes containing runs of contiguous guanines are not gene-specific

High Density Oligonucleotide arrays (HDONAs), such as the Affymetrix HG-U133A GeneChip, use sets of probes chosen to match specified genes, with the expectation that if a particular gene is highly expressed then all the probes in the designated probe set will provide a consistent message signifying the gene's presence. However, we demonstrate by data mining thousands of CEL files from NCBI's GEO database that 4G-probes (defined as probes containing sequences of four or more consecutive guanine (G) bases) do not react in the intended way. Rather, possibly due to the formation of G-quadruplexes, most 4G-probes are correlated, irrespective of the expression of the thousands of genes for which they were separately intended. It follows that 4G-probes should be ignored when calculating gene expression levels. Furthermore, future microarray designs should make no use of 4G-probes

Development of subminiature multi-sensor hot-wire probes

Limitations on the spatial resolution of multisensor hot wire probes have precluded accurate measurements of Reynolds stresses very near solid surfaces in wind tunnels and in many practical aerodynamic flows. The fabrication, calibration and qualification testing of very small single horizontal and X-array hot-wire probes which are intended to be used near solid boundaries in turbulent flows where length scales are particularly small, is described. Details of the sensor fabrication procedure are reported, along with information needed to successfully operate the probes. As compared with conventional probes, manufacture of the subminiature probes is more complex, requiring special equipment and careful handling. The subminiature probes tested were more fragile and shorter lived than conventional probes; they obeyed the same calibration laws but with slightly larger experimental uncertainty. In spite of these disadvantages, measurements of mean statistical quantities and spectra demonstrate the ability of the subminiature sensors to provide the measurements in the near wall region of turbulent boundary layers that are more accurate than conventional sized probes

QCD & QGP: A Summary

Contents: 1. The Thermodynamics of Quarks and Gluons 2. Hard Probes: Colour Deconfinement 3. Electromagnetic Probes: Chiral Symmetry Restoration 4. Soft Probes: Equilibration and Expansion 5. ConclusionsComment: 20 pages, Latex; Theory Summary, International Conference on the Physics and Astrophysics of the Quark-Gluon Plasma (ICPA-QGP'97), Jaipur/India, March 15 - 21, 199

A novel cassette method for probe evaluation in the designed biochips

A critical step in biochip design is the selection of probes with identical hybridisation characteristics. In this article we describe a novel method for evaluating DNA hybridisation probes, allowing the fine-tuning of biochips, that uses cassettes with multiple probes. Each cassette contains probes in equimolar proportions so that their hybridisation performance can be assessed in a single reaction. The model used to demonstrate this method was a series of probes developed to detect TORCH pathogens. DNA probes were designed for Toxoplasma gondii, Chlamidia trachomatis, Rubella, Cytomegalovirus, and Herpes virus and these were used to construct the DNA cassettes. Five cassettes were constructed to detect TORCH pathogens using a variety of genes coding for membrane proteins, viral matrix protein, an early expressed viral protein, viral DNA polymerase and the repetitive gene B1 of Toxoplasma gondii. All of these probes, except that for the B1 gene, exhibited similar profiles under the same hybridisation conditions. The failure of the B1 gene probe to hybridise was not due to a position effect, and this indicated that the probe was unsuitable for inclusion in the biochip. The redesigned probe for the B1 gene exhibited identical hybridisation properties to the other probes, suitable for inclusion in a biochip

Jet-hadron correlations in STAR

Advancements in full jet reconstruction have made it possible to use jets as triggers in azimuthal angular correlations to study the modification of hard-scattered partons in the medium created in ultrarelativistic heavy-ion collisions. This increases the range of parton energies accessible in these analyses and improves the signal-to-background ratio compared to dihadron correlations. Results of a systematic study of jet-hadron correlations in central Au-Au collisions at sqrt(s_NN) = 200 GeV are indicative of a broadening and softening of jets which interact with the medium. Furthermore, jet-hadron correlations suggest that the suppression of the associated hadron yield at high-pT is balanced in large part by low-pT enhancement.Comment: 4 pages, 2 figures, proceedings for Quark Matter 201

Open questions in quarkonium and electromagnetic probes

In my ("not a summary") talk at the Hard Probes 2006 conference, I gave "a personal and surely biased view on only a few of the many open questions on quarkonium and electromagnetic probes". Some of the points reported in that talk are exposed in this paper, having in mind the most important of all the open questions: do we have, today, from experimental data on electromagnetic probes and quarkonium production, convincing evidence that shows, beyond reasonable doubt, the existence of "new physics" in high-energy heavy-ion collisions?Comment: Invited talk at the 2nd Int. Conf. on Hard and EM Probes of High-Energy Nuclear Collisions, Asilomar, California, June 9--16, 2006. To be published in Nuclear Physics A. Late submission to the arXi

Performance of P-P and P-U intensity probes using Scan & Paint

This paper aims to clarify the principal advantages and disadvantages of using sound intensity probes which implement different measurement principles: p-p probes versus p-u probes or Microflowns. A novel measurement technique based on scanning principles called “Scan & Paint” had been chosen to evaluate their performanc