Review: the predictability of the extra-tropical stratosphere on monthly timescales and its impact on the skill of tropospheric forecasts

Extreme variability of the winter- and spring-time stratospheric polar vortex has been shown to affect extratropical tropospheric weather. Therefore, reducing stratospheric forecast error may be one way to improve the skill of tropospheric weather forecasts. In this review, the basis for this idea is examined. A range of studies of different stratospheric extreme vortex events shows that they can be skilfully forecasted beyond five days and into the sub-seasonal range (0-30 days) in some cases. Separate studies show that typical errors in forecasting a stratospheric extreme vortex event can alter tropospheric forecasts skill by 5-7% in the extratropics on sub-seasonal timescales. Thus understanding what limits stratospheric predictability is of significant interest to operational forecasting centres. Both limitations in forecasting tropospheric planetary waves and stratospheric model biases have been shown to be important in this context.

Kim Besio, Ziskind Professor of East Asian Studies

Kim Besio, Ziskind Professor of East Asian Studies

Periodic orbits and non-integrability of Armbruster-Guckenheimer-Kim potential

In this paper we study the periodic orbits of the Hamiltonian system with the Armburster-Guckenheimer Kim potential and its C1 non-integrability in the sense of Liouville-Arnold.

Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC

We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.

Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV

The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.

Bayesian dual threshold design with Dirichlet distribution: An alternative way to frequentist multi-stage phase II designs in oncology

Many phase II clinical studies in oncology use two-stage frequentist design such as Simon's optimal design. However, they have a common logistical problem regarding the patient accrual at the interim. Strictly speaking, patient accrual at the end of the first stage may have to be suspended until all patients have events, success or failure. For example, when the study endpoint is six-month progression free survival, patient accrual has to be stopped until all outcomes from stage I is observed. However, study investigators may have concern when accrual is suspended after the first stage due to the loss of accrual momentum during this hiatus. We propose a two-stage phase II design that resolves the patient accrual problem due to an interim analysis, and it can be used as an alternative way to frequentist two-stage phase II studies in oncology. ^

The Pity of Achilles. Oral Style and the Unity of Iliad, de Jinyo Kim

Fil: Pepe de Suárez, Luz Enriqueta Aurelia. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Medhi Charef, Emir Kusturika, Spike Lee, Katia Lund, Jordan y Ridley Scott, Stefano Veneruso, y John Woo. Todos los niños invisibles (All the invisible children)

Fil: Vicente, María Eugenia. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

The Pity of Achilles. Oral Style and the Unity of Iliad, de Jinyo Kim

Fil: Pepe de Suárez, Luz Enriqueta Aurelia. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Medhi Charef, Emir Kusturika, Spike Lee, Katia Lund, Jordan y Ridley Scott, Stefano Veneruso, y John Woo. Todos los niños invisibles (All the invisible children)

Fil: Vicente, María Eugenia. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

The Pity of Achilles. Oral Style and the Unity of Iliad, de Jinyo Kim

Fil: Pepe de Suárez, Luz Enriqueta Aurelia. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Medhi Charef, Emir Kusturika, Spike Lee, Katia Lund, Jordan y Ridley Scott, Stefano Veneruso, y John Woo. Todos los niños invisibles (All the invisible children)

Fil: D'Assaro, Adriana. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.