61,257 research outputs found
Bioinformatics: A challenge for statisticians
Bioinformatics is a subject that requires the skills of biologists, computer scientists, mathematicians and staisticians. This paper introduces the reader to one small aspect of the subject: the study of microarrays. It describes some of the complexities of the enormous amounts of data that are available and shows how simple statistical techniques can be used to highlight deficiencies in that data
Temporal evolution of multiple evaporating ribbon sources in a solar flare
We present new results from the Interface Region Imaging Spectrograph showing
the dynamic evolution of chromospheric evaporation and condensation in a flare
ribbon, with the highest temporal and spatial resolution to date. IRIS observed
the entire impulsive phase of the X-class flare SOL2014-09-10T17:45 using a 9.4
second cadence `sit-and-stare' mode. As the ribbon brightened successively at
new positions along the slit, a unique impulsive phase evolution was observed
for many tens of individual pixels in both coronal and chromospheric lines.
Each activation of a new footpoint displays the same initial coronal up-flows
of up to ~300 km/s, and chromospheric downflows up to 40 km/s. Although the
coronal flows can be delayed by over 1 minute with respect to those in the
chromosphere, the temporal evolution of flows is strikingly similar between all
pixels, and consistent with predictions from hydrodynamic flare models. Given
the large sample of independent footpoints, we conclude that each flaring pixel
can be considered a prototypical, `elementary' flare kernel.Comment: Accepted for publication - ApJ letter
Search for direct top quark pair production in final states with one isolated lepton, jets, and missing transverse momentum in √s=7 TeV pp collisions using 4.7 fb-1 of ATLAS data
A search is presented for direct top squark pair production in final states with one isolated electron or muon, jets, and missing transverse momentum in proton-proton collisions at √s=7 TeV. The measurement is based on 4.7 fb-1 of data collected with the ATLAS detector at the LHC. Each top squark is assumed to decay to a top quark and the lightest supersymmetric particle (LSP). The data are found to be consistent with standard model expectations. Top squark masses between 230 GeV and 440 GeV are excluded with 95% confidence for massless LSPs, and top squark masses around 400 GeV are excluded for LSP masses up to 125 GeV
Inertial Spontaneous Symmetry Breaking and Quantum Scale Invariance
Weyl invariant theories of scalars and gravity can generate all mass scales
spontaneously, initiated by a dynamical process of "inertial spontaneous
symmetry breaking" that does not involve a potential. This is dictated by the
structure of the Weyl current, , and a cosmological phase during which
the universe expands and the Einstein-Hilbert effective action is formed.
Maintaining exact Weyl invariance in the renormalised quantum theory is
straightforward when renormalisation conditions are referred back to the VEV's
of fields in the action of the theory, which implies a conserved Weyl current.
We do not require scale invariant regulators. We illustrate the computation of
a Weyl invariant Coleman-Weinberg potential
Measurements of Wγ and Zγ production in pp collisions at √s=7 TeV with the ATLAS detector at the LHC
The integrated and differential fiducial cross sections for the production of a W or Z boson in association with a high-energy photon are measured using pp collisions at √s = 7 TeV. The analyses use a data sample with an integrated luminosity of 4.6 fb(-1) collected by the ATLAS detector during the 2011 LHC data-taking period. Events are selected using leptonic decays of the W and Z bosons [W eν , μ ν ) and Z(e+ e-, μ+μ-, νν-)] with the requirement of an associated isolated photon. The data are used to test the electroweak sector of the Standard Model and search for evidence for new phenomena. The measurements are used to probe the anomalous WWγ , ZZγ, and Zγγ triple-gauge-boson couplings and to search for the production of vector resonances decaying to Zγ and Wγ. No deviations from Standard Model predictions are observed and limits are placed on anomalous triple-gauge-boson couplings and on the production of new vector meson resonances
Saccharomyces cerevisiae in the production of fermented beverages
Alcoholic beverages are produced following the fermentation of sugars by yeasts, mainly (but not exclusively) strains of the species, Saccharomyces cerevisiae. The sugary starting materials may emanate from cereal starches (which require enzymatic pre‐hydrolysis) in the case of beers and whiskies, sucrose‐rich plants (molasses or sugar juice from sugarcane) in the case of rums, or from fruits (which do not require pre‐hydrolysis) in the case of wines and brandies. In the presence of sugars, together with other essential nutrients such as amino acids, minerals and vitamins, S. cerevisiae will conduct fermentative metabolism to ethanol and carbon dioxide (as the primary fermentation metabolites) as the cells strive to make energy and regenerate the coenzyme NAD+ under anaerobic conditions. Yeasts will also produce numerous secondary metabolites which act as important beverage flavour congeners, including higher alcohols, esters, carbonyls and sulphur compounds. These are very important in dictating the final flavour and aroma characteristics of beverages such as beer and wine, but also in distilled beverages such as whisky, rum and brandy. Therefore, yeasts are of vital importance in providing the alcohol content and the sensory profiles of beverages. This Introductory Chapter reviews, in general, the growth, physiology and metabolism of S. cerevisiae in alcoholic beverage fermentations
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