Top quarks are produced in pairs via the strong interaction. At the Tevatron, operating at 1.96 TeV in Run II, the expected production rate of tt pairs is 6.8±0.6 pb @ mt=175 GeV/c . Roughly 85% arise from qq interactions, while the remaining 15% are created by gluon fusion. As of February 4, 2007, 2.05 fb of data have been recorded by the D0 experiment. To study the properties of the top quark...

We discuss the circumstances under which the bending of a jet can generate an internal shock wave. The analysis is carried out for relativistic and non–relativistic astrophysical jets. The calculations are done by the method of characteristics for the case of steady simple waves. This generalises the non–relativistic treatment first used by Icke (1991). We show that it is possible to obtain an ...

The plasma jet has been proposed as a novel therapeutic method for anticancer treatment. However, its biological effects and mechanism of action remain elusive. Here, we investigated its cell death effects and underlying molecular mechanisms, using air and N₂ plasma jets from a micro nozzle array. Treatment with air or N₂ plasma jets caused apoptotic death in human cervical cancer HeLa cells, s...

We conduct hydrodynamical numerical simulations and find that precessing massive slow jets can inflate fat bubbles, i.e., more or less spherical bubbles, that are attached to the center of clusters of galaxies. To inflate a fat bubble the jet should precess fast. The precessing angle θ should be large, or change over a large range 0 ≤ θ ≤ θmax ∼ 30 − 70 ◦ (depending also on other parameters), w...

Comparing the properties AGN and Herbig-Haro jets can be a useful exercise for understanding the physical mechanisms at work in collimated outflows that propagate in such different environments. In the case of Herbig-Haro jets, the presence of emission lines in the spectra and the continuous evolution of the observation techniques greatly favor our knowledge of the physical parameters of the je...

Measurements are presented of the cross section for the production of at least four jets, of which at least two originate from b quarks, in proton-proton collisions. Data collected with the CMS detector at the LHC at a center-of-mass energy of 7 TeV are used, corresponding to an integrated luminosity of 3 pb−1. The cross section is measured as a function of the jet transverse momentum for pT > ...

Local Gabor features (jets) have been widely used in face recognition systems. Once the sets of jets have been extracted from the two faces to be compared, a proper measure of similarity (or distance) between corresponding features should be chosen. For instance, in the well known Elastic Bunch Graph Matching (EBGM) approach and other Gabor-based face recognition systems, the cosine distance wa...

We calculate the mean number of subjets in quark and gluon jets in the final state of ee annihilation. Since “quark” and “gluon” jets are schemedependent objects, we stress the importance of using the same definition as in experimental analyses. We define the jets using the k⊥ algorithm at a coarse scale y1, and the subjets using a finer scale y0, in the same algorithm. Gluon jets are anti-tagg...

I derive constraints on jet properties for inflating pairs of bubbles in planetary nebulae and clusters of galaxies. This work is motivated by the similarity in morphology and some non-dimensional quantities between X-ray-deficient bubbles in clusters of galaxies and the optical-deficient bubbles in planetary nebulae, which was pointed out in an earlier work. In the present paper I find that fo...

Centrifugal pressure of matter spiralling onto black holes, have long been known to produce standing or oscillating shocks. The post-shock disc puffs up in the form of a torus, which intercepts soft photons from the outer Keplerian disc and inverse Comptonizes them to produce hard photons. The post-shock region also produces jets. We study the interaction of both hard photons and soft photons, ...