Searches for long-lived charged particles with the ATLAS experiment

These conference proceedings for PLHC 2011 in Perugia, Italy summarize the results from two searches for long-lived charged particles using 34-37 pb-1. The searches are based on direct detection and exploits ionization energy loss and time-of-flight measurements to separate slow-moving signal particles from the Standard Model backgrounds. The observations are in all cases consistent with the background-only hypotheses and limits are presented for long-lived squarks, gluinos and sleptons.Comment: 2 pages, 2 figures, proceedings for Physics at the LHC in Perugia, Italy, June 6-11, 201

Collider Searches for Long-Lived Particles Beyond the Standard Model

Experimental tests of the Standard Model of particle physics (SM) find excellent agreement with its predictions. Since the original formation of the SM, experiments have provided little guidance regarding the explanations of phenomena outside the SM, such as the baryon asymmetry and dark matter. Nor have we understood the aesthetic and theoretical problems of the SM, despite years of searching for physics beyond the Standard Model (BSM) at particle colliders. Some BSM particles can be produced at colliders yet evade being discovered, if the reconstruction and analysis procedures not matched to characteristics of the particle. An example is particles with large lifetimes. As interest in searches for such long-lived particles (LLPs) grows rapidly, a review of the topic is presented in this article. The broad range of theoretical motivations for LLPs and the experimental strategies and methods employed to search for them are described. Results from decades of LLP searches are reviewed, as are opportunities for the next generation of searches at both existing and future experiments.Comment: 79 pages, 36 figures, submitted to Progress in Particle and Nuclear Physic

GVC: efficient random access compression for gene sequence variations

Background: In recent years, advances in high-throughput sequencing technologies have enabled the use of genomic information in many fields, such as precision medicine, oncology, and food quality control. The amount of genomic data being generated is growing rapidly and is expected to soon surpass the amount of video data. The majority of sequencing experiments, such as genome-wide association studies, have the goal of identifying variations in the gene sequence to better understand phenotypic variations. We present a novel approach for compressing gene sequence variations with random access capability: the Genomic Variant Codec (GVC). We use techniques such as binarization, joint row- and column-wise sorting of blocks of variations, as well as the image compression standard JBIG for efficient entropy coding. Results: Our results show that GVC provides the best trade-off between compression and random access compared to the state of the art: it reduces the genotype information size from 758 GiB down to 890 MiB on the publicly available 1000 Genomes Project (phase 3) data, which is 21% less than the state of the art in random-access capable methods. Conclusions: By providing the best results in terms of combined random access and compression, GVC facilitates the efficient storage of large collections of gene sequence variations. In particular, the random access capability of GVC enables seamless remote data access and application integration. The software is open source and available at https://github.com/sXperfect/gvc/

C5aR1 Activation Drives Early IFN-gamma Production to Control ExperimentalToxoplasma gondiiInfection

Toxoplasma gondii (T. gondii) is a parasite infecting animals and humans. In intermediate hosts, such as humans or rodents, rapidly replicating tachyzoites drive vigorous innate and adaptive immune responses resulting in bradyzoites that survive within tissue cysts. Activation of the innate immune system is critical during the early phase of infection to limit pathogen growth and to instruct parasite-specific adaptive immunity. In rodents, dendritic cells (DCs) senseT. gondiithrough TLR11/12, leading to IL-12 production, which activates NK cells to produce IFN-gamma as an essential mechanism for early parasite control. Further, C3 can bind toT. gondiiresulting in limited complement activation. Here, we determined the role of C5a/C5aR1 axis activation for the early innate immune response in a mouse model of peritonealT. gondiiinfection. We found thatC5ar1(-/-)animals suffered from significantly higher weight loss, disease severity, mortality, and parasite burden in the brain than wild type control animals. Severe infection inC5ar1(-/-)mice was associated with diminished serum concentrations of IL-12, IL-27, and IFN-gamma. Importantly, the serum levels of pro-inflammatory cytokines, including IL-1 alpha, IL-6, and TNF-alpha, as well as several CXC and CC chemokines, were decreased in comparison to wt animals, whereas anti-inflammatory IL-10 was elevated. The defect in IFN-gamma production was associated with diminishedIfngmRNA expression in the spleen and the brain, reduced frequency of IFN-gamma+NK cells in the spleen, and decreasedNos2expression in the brain ofC5ar1(-/-)mice. Mechanistically, DCs from the spleen ofC5ar1(-/-)mice produced significantly less IL-12 in response to soluble tachyzoite antigen (STAg) stimulationin vivoandin vitro. Our findings suggest a model in which the C5a/C5aR1 axis promotes IL-12 induction in splenic DCs that is critical for IFN-gamma production from NK cells and subsequent iNOS expression in the brain as a critical mechanism to control acuteT. gondiiinfection