The AEP algorithm for the fast computation of the distribution of the sum of dependent random variables

We propose a new algorithm to compute numerically the distribution function of the sum of $d$ dependent, non-negative random variables with given joint distribution.Comment: Published in at http://dx.doi.org/10.3150/10-BEJ284 the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

Targeting the acute promyelocytic leukemia-associated fusion proteins PML/RARα and PLZF/RARα with interfering peptides

In acute promyelocytic leukemia (APL), hematopoietic differentiation is blocked and immature blasts accumulate in the bone marrow and blood. APL is associated with chromosomal aberrations, including t(15;17) and t(11;17). For these two translocations, the retinoic acid receptor alpha (RARα) is fused to the promyelocytic leukemia (PML) gene or the promyelocytic zinc finger (PLZF) gene, respectively. Both fusion proteins lead to the formation of a high-molecular-weight complex. High-molecular-weight complexes are caused by the “coiled-coil” domain of PML or the BTB/POZ domain of PLZF. PML/RARα without the “coiled-coil” fails to block differentiation and mediates an all-trans retinoic acid-response. Similarly, mutations in the BTB/POZ domain disrupt the high-molecular-weight complex, abolishing the leukemic potential of PLZF/RARα. Specific interfering polypeptides were used to target the oligomerization domain of PML/RARα or PLZF/RARα. PML/RARα and PLZF/RARα were analyzed for the ability to form high-molecular-weight complexes, the protein stability and the potential to induce a leukemic phenotype in the presence of the interfering peptides. Expression of these interfering peptides resulted in a reduced replating efficiency and overcame the differentiation block induced by PML/RARα and PLZF/RARα in murine hematopoietic stem cells. This expression also destabilized the PLZF/RARα-induced high-molecular-weight complex formation and caused the degradation of the fusion protein. Targeting fusion proteins through interfering peptides is a promising approach to further elucidate the biology of leukemia

SVILUPPO DI NUOVE TECNOLOGIE PER LA ESTRAZIONE DI BLOCCHI DI GRANITO DOPO LA PERFORAZIONE

In questo documento viene proposta una nuova tecnologia per sezionare le bancate di granito in blocchi, dopo la perforazione, in modo sicuro ed economico. Il lavoro è stato svolto interamente presso la Dazzini s.r.l., ditta affermata nel settore di escavazione dei materiali lapidei la quale vanta un’esperienza nel settore pluritrentennale. Inizialmente si illustrano le tecniche della coltivazione delle cave ornamentali ed in particolar modo di quelle utilizzate per il taglio del granito. Sono stati confrontati i prodotti e le tecniche usate attualmente in relazione al costo, alla facilità d’uso, alle competenze richieste dal personale evidenziando i vantaggi e gli svantaggi nel loro utilizzo. Successivamente si illustra la progettazione e la realizzazione della nuova tecnologia. Infine si sono effettuate delle prove sperimentali su blocchi di granito per verificarne il funzionamento e la praticità

Time delays between Fermi LAT and GBM light curves of GRBs

Most Gamma-Ray Bursts (GRBs) detected by the Fermi Gamma-ray Space Telescope exhibit a delay of up to about 10 seconds between the trigger time of the hard X-ray signal as measured by the Fermi GBM and the onset of the MeV-GeV counterpart detected by the LAT. This delay may hint at important physics, whether it is due to the intrinsic variability of the inner engine or it is related to quantum dispersion effects in the velocity of light propagation from the sources to the observer. It is critical to have a proper assessment of how these time delays affect the overall properties of the light curves. We cross-correlated the 5 brightest GRBs of the 1st Fermi LAT Catalog by means of the continuous correlation function (CCF) and of the Discrete Correlation Function (DCF). A maximum in the DCF suggests the presence of a time lag between the curves, whose value and uncertainty are estimated through a Gaussian fitting of the DCF profile and light curve simulation via a Monte Carlo approach. The cross-correlation of the observed LAT and GBM light curves yields time lags that are mostly similar to those reported in the literature, but they are formally consistent with zero. The cross-correlation of the simulated light curves yields smaller errors on the time lags and more than one time lag for GRBs 090902B and 090926A; for all 5 GRBs, the time lags are significantly different from zero and consistent with those reported in the literature, when only the secondary maxima are considered for those two GRBs. The DCF method evidences the presence of time lags between the LAT and GBM light curves and underlines their complexity. While this suggests that the delays should be ascribed to intrinsic physical mechanisms, more sensitivity and larger statistics are needed to assess whether time lags are universally present in the early GRB emission and which dynamical time scales they trace.Comment: 9 pages, 3 figures, accepted for publication in Astronomy & Astrophysic

Computation of sharp bounds on the distribution of a function of dependent risks

AbstractWe propose a new algorithm to compute numerically sharp lower and upper bounds on the distribution of a function of d dependent random variables having fixed marginal distributions. Compared to the existing literature, the bounds are widely applicable, more accurate and more easily obtained