16 research outputs found
Space-time evolution of hadronization
Beside its intrinsic interest for the insights it can give into color
confinement, knowledge of the space-time evolution of hadronization is very
important for correctly interpreting jet-quenching data in heavy ion collisions
and extracting the properties of the produced medium. On the experimental side,
the cleanest environment to study the space-time evolution of hadronization is
semi-inclusive Deeply Inelastic Scattering on nuclear targets. On the
theoretical side, 2 frameworks are presently competing to explain the observed
attenuation of hadron production: quark energy loss (with hadron formation
outside the nucleus) and nuclear absorption (with hadronization starting inside
the nucleus). I discuss recent observables and ideas which will help to
distinguish these 2 mechanisms and to measure the time scales of the
hadronization process.Comment: 6 pages, 4 figures. Based on talks given at "Hot Quarks 2006",
Villasimius, Italy, May 15-20, 2006, and at the "XLIV internataional winter
meeting on nuclear physics", Bormio, Italy, Jan 29 - Feb 5, 2006. To appear
in Eur.Phys.J.
Experimental and Theoretical Challenges in the Search for the Quark Gluon Plasma: The STAR Collaboration's Critical Assessment of the Evidence from RHIC Collisions
We review the most important experimental results from the first three years
of nucleus-nucleus collision studies at RHIC, with emphasis on results from the
STAR experiment, and we assess their interpretation and comparison to theory.
The theory-experiment comparison suggests that central Au+Au collisions at RHIC
produce dense, rapidly thermalizing matter characterized by: (1) initial energy
densities above the critical values predicted by lattice QCD for establishment
of a Quark-Gluon Plasma (QGP); (2) nearly ideal fluid flow, marked by
constituent interactions of very short mean free path, established most
probably at a stage preceding hadron formation; and (3) opacity to jets. Many
of the observations are consistent with models incorporating QGP formation in
the early collision stages, and have not found ready explanation in a hadronic
framework. However, the measurements themselves do not yet establish
unequivocal evidence for a transition to this new form of matter. The
theoretical treatment of the collision evolution, despite impressive successes,
invokes a suite of distinct models, degrees of freedom and assumptions of as
yet unknown quantitative consequence. We pose a set of important open
questions, and suggest additional measurements, at least some of which should
be addressed in order to establish a compelling basis to conclude definitively
that thermalized, deconfined quark-gluon matter has been produced at RHIC.Comment: 101 pages, 37 figures; revised version to Nucl. Phys.
Large expert-curated database for benchmarking document similarity detection in biomedical literature search
Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe
Individual and contextual characteristics of the German extreme right-wing vote in the 1990's: A test of complementary theories
Contains fulltext :
17099.pdf (publisher's version ) (Closed access)In this article we set out to improve our knowledge on voting for extreme right-wing parties, i.e. the Republikaner, by taking into account social, political and contextual characteristics. We test four theories that provide explanations as to why certain social categories are more likely to vote for the Republikaner. The hypotheses are tested with multilevel analyses, with data from a national sample (N = 4688). Multinomial analyses provide additional information on how theoretically derived political attitudes effect voting behaviour