THEMES IN MODERN AFRICAN HISTORY AND CULTURE Festschrift for Tekeste Negash

none2Modern African Historiography State and Society Reflection on Basis Themes in African Studies and MethodologiesopenLars Berge; Irma TaddiaLars Berge; Irma Taddi

Review of particle physics

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,283 new measurements from 899 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as heavy neutrinos, supersymmetric and technicolor particles, axions, dark photons, etc. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as Supersymmetry, Extra Dimensions, Particle Detectors, Probability, and Statistics. Among the 112 reviews are many that are new or heavily revised including those on: Dark Energy, Higgs Boson Physics, Electroweak Model, Neutrino Cross Section Measurements, Monte Carlo Neutrino Generators, Top Quark, Dark Matter, Dynamical Electroweak Symmetry Breaking, Accelerator Physics of Colliders, High-Energy Collider Parameters, Big Bang Nucleosynthesis, Astrophysical Constants and Cosmological Parameters. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.Ibi.gov

Review of particle physics

This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2658 new measurements from 644 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 112 reviews are many that are new or heavily revised including those on Heavy-Quark and Soft-Collinear Effective Theory, Neutrino Cross Section Measurements, Monte Carlo Event Generators, Lattice QCD, Heavy Quarkonium Spectroscopy, Top Quark, Dark Matter, Vcb& Vub, Quantum Chromodynamics, High-Energy Collider Parameters, Astrophysical Constants, Cosmological Parameters, and Dark Matter. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov/. The 2012 edition of Review of Particle Physics is published for the Particle Data Group as article 010001 in volume 86 of Physical Review D. This edition should be cited as: J. Beringer et al. (Particle Data Group), Phys. Rev. D 86, 010001 (2012). © 2012 Regents of the University of California

Collective behavior and morphological complexity in Pseudomonas aeruginosa

In nature, many animals are capable of performing complex behaviors without centralized coordination. A well-studied focus is collective motion in flocks of birds and shoals of fish, both of which are capable of changing collective behavior as a function of individuals responding to their local environment. Similarly, despite their microscopic individual size, groups of bacteria are capable of collectively responding to and restructuring their environment. In this thesis I focus on the gamma proteobacterium Pseudomonas aeruginosa (PA), a well-studied opportunistic pathogen that is known to engage in complex collective behaviors, often controlled by a form of cell-cell communication mediated by diffusible signal molecules called quorum sensing (QS). First, I query the sensing capacity of QS, quantifying the ability to sense cell density by tracking QS-regulated secreted protease (lasB) expression on the population and single-cell scale. We find that PA can deliver a graded behavioral response (or ‘reaction norm’) to fine-scale variation in population density and show that populations generate graded responses to environmental variation through shifts in the proportion of cells responding and the intensity of responses. Given this ability of PA to quantitatively respond to discrete density environments, I then ask how the molecular machinery of QS shapes the reaction norms to changing density, via signal synthase knockout and complementation experiments. We find that the wildtype reaction norm is robust to the addition of density-independent signal supplements and more broadly, that a positive reaction norm to density is robust to multiple combinations of gene deletion and density-independent signal supplementation. Switching from QS control of a single gene (lasB), I turn to a complex multigenic and multicellular trait of colony growth. Using a collection of diverse environmental and clinical PA isolates, we develop a colony image library of 69 strains in four-fold replication. We then use a combination of image processing techniques to quantify colony morphology and complexity and find that, under common laboratory conditions, morphology and complexity form a robust, repeatable phenotype on the level of individual strains. Based on this replicable visual “fingerprint” per strain, we reasoned that colony image data could be used to classify previously unseen colony images to the strain level. Using a combination of transfer learning and data augmentation we trained a neural network to classify strains, resulting in high-level accuracy (94%). These results indicate that not only do PA strains have characteristic, replicable ‘fingerprints’, but also that these ‘fingerprints’ are learnable and classifiable. These results could provide a basis for predicting other strain-dependent behaviors including virulence or antibiotic resistance. Overall, these results highlight that complex and heterogeneous single-cell behaviors can produce robust and consistent patterns on the collective scale of environmental sensing and colony growth.Ph.D