Software debugging techniques

This lecture provides an introduction to debugging, a crucial activity in every developer's life. After an elementary discussion of some useful debugging concepts, the lecture goes on with a detailed review of general debugging techniques, independent of any speci c software. The nal part of the lecture is dedicated to analysing problems related to the use of C++ , the main programming language commonly employed in particle physics nowadays

The Online Histogram Presenter for the ATLAS experiment: a modular system for histogram visualization

The Online Histogram Presenter (OHP) is the ATLAS tool to display histograms produced by the online monitoring system. In spite of the name, the Online Histogram Presenter is much more than just a histogram display. To cope with the large amount of data, the application has been designed to minimise the network traffic; sophisticated caching, hashing and filtering algorithms reduce memory and CPU usage. The system uses Qt and ROOT for histogram visualisation and manipulation. In addition, histogram visualisation can be extensively customised through configuration files. Finally, its very modular architecture features a lightweight plug-in system, allowing extensions to accommodate specific user needs. After an architectural overview of the application, the paper is going to present in detail the solutions adopted to increase the performance and a description of the plug-in system

A thermodynamic study of electroneutral K-Cl cotransport in pH- and volume-clamped low K sheep erythrocytes with normal and low internal magnesium.

Swelling-Induced human erythrocyte K-Cl cotransport is membrane potential independent and capable of uphill transport. However, a complete thermodynamic analysis of basal and stimulated K-Cl cotransport, at constant cell volume, is missing, This study was performed in low K sheep red blood cells before and after reducing cellular free Mg into the nanomolar range with the divalent cation ionophore A23187 and a chelator, an intervention known to stimulate K-Cl cotransport. The anion exchange inhibitor 4,4\u27diisothiocyanato-2,2\u27disulfonic stilbene was used to clamp intracellular pH and Cl or NO3 concentrations. Cell volume was maintained constant as external and internal pH differed by more than two units. K-Cl cotransport was calculated from the K effluxes and Rb (as K congener) influxes measured in Cl and NO3 at constant internal K and external anions, and variable concentrations of extracellular Rb and internal anions, respectively. The external Rb concentration at which net K-Cl cotransport is zero was defined as flux reversal point which changed with internal pH and hence Cl. Plots of the ratio of external Rb concentrations corresponding to the flux reversal points and the internal Ii concentration versus the ratio of the internal and external Cl concentrations (i.e., the Donnan ratio of the transported ions) yielded slopes near unity for both control and low internal Mg cells. Thus, basal as well as low internal Mg-stimulated net K-Cl cotransport depends on the electrochemical potential gradient of KCl

GNAM and OHP: Monitoring Tools for ATLAS experiment at LHC.

ATLAS is one of the four experiments under construction along the Large Hadron Collider (LHC) ring at CERN. The LHC will produce interactions at a center-of-mass energy equal to âs = 14 TeV at 40 MHz rate. The detector consists of more than 140 million electronic channels. The challenging experimental environment and the extreme detector complexity impose the necessity of a common scalable distributed monitoring framework, which can be tuned for the optimal use by different ATLAS sub-detectors at the various levels of the ATLAS data flow. This note presents two monitoring tools that have been developed for this aim within the architecture ATLAS Monitoring Framework and the Data Acquisition System: GNAM and OHP. The first one is a framework for online histogram production; the second one is graphical application for histogram presentation. This tools are now widely used during the ATLAS commissioning and their performances are reported in this not

Search for Dark Matter Candidates and Large Extra Dimensions in Events with a Photon and Missing Transverse Momentum in pp Collision Data at s√=7 TeV with the ATLAS Detector

Results of a search for new phenomena in events with an energetic photon and large missing transverse momentum in proton-proton collisions at s√=7  TeV are reported. Data collected by the ATLAS experiment at the LHC corresponding to an integrated luminosity of 4.6  fb−1 are used. Good agreement is observed between the data and the standard model predictions. The results are translated into exclusion limits on models with large extra spatial dimensions and on pair production of weakly interacting dark matter candidates