A \u27Big Potty\u27 with My Big Sister

The summer of ‘82. It was going to be the best vacation ever! I was 10 years old. After the hard knocks and heartbreak of fourth grade, I needed a vacation

Associated production of Higgs and single top at hadron colliders

We study the production of the Higgs boson in association with a single top quark at hadron colliders. The cross sections for the three production processes (t-channel, s-channel, and W-associated) at both the Tevatron and the LHC are presented. We investigate the possibility of detecting a signal for the largest of these processes, the t-channel process at the LHC, via the Higgs decay into b b-bar. The QCD backgrounds are large and difficult to curb, hindering the extraction of the signal. Extensions of our analysis to the production of supersymmetric Higgs bosons are also addressed. The cross section is enhanced for large values of tangent beta, increasing the prospects for extracting a signal

Color-flow decomposition of QCD amplitudes

We introduce a new color decomposition for multi-parton amplitudes in QCD, free of fundamental-representation matrices and structure constants. This decomposition has a physical interpretation in terms of the flow of color, which makes it ideal for merging with shower Monte-Carlo programs. The color-flow decomposition allows for very efficient evaluation of amplitudes with many quarks and gluons, many times faster than the standard color decomposition based on fundamental-representation matrices. This will increase the speed of event generators for multi-jet processes, which are the principal backgrounds to signals of new physics at colliders.Comment: 23 pages, 11 figures, version to appear on Phys. Rev.

Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche.

Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P < 5 × 10(-8)) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1-WDR25, MKRN3-MAGEL2 and KCNK9) demonstrating parent-of-origin-specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and γ-aminobutyric acid-B2 receptor signalling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition

Effect of Muscle Length on Cross-Bridge Kinetics in Intact Cardiac Trabeculae at Body Temperature

Dynamic force generation in cardiac muscle, which determines cardiac pumping activity, depends on both the number of sarcomeric cross-bridges and on their cycling kinetics. The Frank–Starling mechanism dictates that cardiac force development increases with increasing cardiac muscle length (corresponding to increased ventricular volume). It is, however, unclear to what extent this increase in cardiac muscle length affects the rate of cross-bridge cycling. Previous studies using permeabilized cardiac preparations, sub-physiological temperatures, or both have obtained conflicting results. Here, we developed a protocol that allowed us to reliably and reproducibly measure the rate of tension redevelopment (ktr; which depends on the rate of cross-bridge cycling) in intact trabeculae at body temperature. Using K+ contractures to induce a tonic level of force, we showed the ktr was slower in rabbit muscle (which contains predominantly β myosin) than in rat muscle (which contains predominantly α myosin). Analyses of ktr in rat muscle at optimal length (Lopt) and 90% of optimal length (L90) revealed that ktr was significantly slower at Lopt (27.7 ± 3.3 and 27.8 ± 3.0 s−1 in duplicate analyses) than at L90 (45.1 ± 7.6 and 47.5 ± 9.2 s−1). We therefore show that ktr can be measured in intact rat and rabbit cardiac trabeculae, and that the ktr decreases when muscles are stretched to their optimal length under near-physiological conditions, indicating that the Frank–Starling mechanism not only increases force but also affects cross-bridge cycling kinetics

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

Baryonic Z′Z' connection of LEP Rb,cR_{b,c} data with Tevatron (W,Z,γ)bbˉ(W,Z,\gamma)b\bar b events

The mixing of a new $Z'$ boson with the $Z$ significantly improves the fit to the LEP precision electroweak data, provided that the $Z'$ couples mainly to quarks. If $M_{Z_2}<200$~GeV, the $s$-channel $Z_2$ production and $(W,Z,\gamma)Z_2$ pair production cross sections at the Tevatron give an excess above QCD of $b\bar b$ and $(W,Z,\gamma)b\bar b$ events, respectively, with invariant mass $m(b\bar b)\approx M_{Z_2}$, which provide viable signals for detection of the $Z_2$. The interference of the $Z_2$ with $\gamma,Z_1$ in $e^+e^-\to \bar bb(\bar cc)$ at LEP\,1.5 energies is correlated with $R_b(R_c)$ and may be observable.Comment: 20 pages, standard Latex, 8 postscript figures (embedded at end of tex file using "\special" command). Complete postscript version available at http://phenom.physics.wisc.edu/pub/preprints/1996/madph-96-936.ps.Z or at ftp://phenom.physics.wisc.edu/pub/preprints/1996/madph-96-936.ps.

Resting cells rely on the DNA helicase component MCM2 to build cilia

Minichromosome maintenance (MCM) proteins facilitate replication by licensing origins and unwinding the DNA double strand. Interestingly, the number of MCM hexamers greatly exceeds the number of firing origins suggesting additional roles of MCMs. Here we show a hitherto unanticipated function of MCM2 in cilia formation in human cells and zebrafish that is uncoupled from replication. Zebrafish depleted of MCM2 develop ciliopathy-phenotypes including microcephaly and aberrant heart looping due to malformed cilia. In non-cycling human fibroblasts, loss of MCM2 promotes transcription of a subset of genes, which cause cilia shortening and centriole overduplication. Chromatin immunoprecipitation experiments show that MCM2 binds to transcription start sites of cilia inhibiting genes. We propose that such binding may block RNA polymerase II-mediated transcription. Depletion of a second MCM (MCM7), which functions in complex with MCM2 during its canonical functions, reveals an overlapping cilia-deficiency phenotype likely unconnected to replication, although MCM7 appears to regulate a distinct subset of genes and pathways. Our data suggests that MCM2 and 7 exert a role in ciliogenesis in post-mitotic tissues

Tevatron-for-LHC Report: Top and Electroweak Physics

The top quark and electroweak bosons (W and Z) represent the most massive fundamental particles yet discovered, and as such refer directly to the Standard Model's greatest remaining mystery: the mechanism by which all particles gained mass. This report summarizes the work done within the top-ew group of the Tevatron-for-LHC workshop. It represents a collection of both Tevatron results, and LHC predictions. The hope is that by considering and comparing both machines, the LHC program can be improved and aided by knowledge from the Tevatron, and that particle physics as a whole can be enriched. The report includes measurements of the top quark mass, searches for single top quark production, and physics of the electroweak bosons at hadron colliders