Measurement of the diffractive structure function in deep inelastic scattering at HERA

This paper presents an analysis of the inclusive properties of diffractive deep inelastic scattering events produced in $ep$ interactions at HERA. The events are characterised by a rapidity gap between the outgoing proton system and the remaining hadronic system. Inclusive distributions are presented and compared with Monte Carlo models for diffractive processes. The data are consistent with models where the pomeron structure function has a hard and a soft contribution. The diffractive structure function is measured as a function of \xpom, the momentum fraction lost by the proton, of $\beta$, the momentum fraction of the struck quark with respect to \xpom, and of $Q^2$. The \xpom dependence is consistent with the form \xpoma where $a~=~1.30~\pm~0.08~(stat)~^{+~0.08}_{-~0.14}~(sys)$ in all bins of $\beta$ and $Q^2$. In the measured $Q^2$ range, the diffractive structure function approximately scales with $Q^2$ at fixed $\beta$. In an Ingelman-Schlein type model, where commonly used pomeron flux factor normalisations are assumed, it is found that the quarks within the pomeron do not saturate the momentum sum rule.Comment: 36 pages, latex, 11 figures appended as uuencoded fil

Observation of hard scattering in photoproduction events with a large rapidity gap at HERA

Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the $\gamma p$ centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil

Observation of Events with an Energetic Forward Neutron in Deep Inelastic Scattering at HERA

In deep inelastic neutral current scattering of positrons and protons at the center of mass energy of 300 GeV, we observe, with the ZEUS detector, events with a high energy neutron produced at very small scattering angles with respect to the proton direction. The events constitute a fixed fraction of the deep inelastic, neutral current event sample independent of Bjorken x and Q2 in the range 3 · 10-4 \u3c xBJ \u3c 6 · 10-3 and 10 \u3c Q2 \u3c 100 GeV2

Application Of Ki-67 Analysis In A Distributed Computing Infrastructure

Introduction/ Background Over the last few years, the protein Ki-67 [1] has been established as one of the most important biomarkers for cell proliferation in breast cancer. High Ki-67 values indicate high tumor growth and have direct impact on the patient’s treatment. Several automated image anal- ysis methods for identifying Ki-67-positive and negative tumor cells have been presented. Aims For small regions of a virtual slide, the Ki-67 analysis can be realized within an acceptable period of time. However, to analyse an entire whole slide image (WSI [2])most of the current methods are not sufficient yet. On a typical office computer, the processing time of 3,752 tiles, which were extracted from a H–DAB stained WSI, exceeded 24 hours. Therefore, we propose an approach to significantly speed up the process of analysing entire WSIs by using a distributed computing infrastructure. Methods To evaluate the approach, an unmodified and validated [3] [4] analysis software for Ki-67 was deployed on a six node setup supporting two different software engines: Hadoop Streaming [5] and Apache Spark [6] . Both tools support the MapReduce methodology whereas Apache Spark offers alternative programing models. In addition, heat maps visualizing the Ki-67 scores for an entire slide were generated which can provide additional informa- tion for clinical research. Results First results on automated and reproducible tests have been produced. By processing 3,752 tiles the speedup turned out to increase linearly with the number of tiles. The overall processing time was improved by a factor of 10, more precisely from 28 hours on a typical office computer to three hours on a distributed environment. Further optimization strategies besides WSI partitioning will be considered. To achieve additional improvements in processing speed, the underlying algorithm of a Ki-67 analysis can be examined with focus on how to adapt it towards distributed processing workflows