Recent results on Charm Physics from Fermilab

New high statistics, high resolution fixed target experiments producing $10^5$ - $10^6$ fully reconstructed charm particles are allowing a detailed study of the charm sector. Recent results on charm quark production from Fermilab fixed target experiments E791, SELEX and FOCUS are presented.Comment: 27 pages, corrected some typographical errors. To appear Proc. VII Mexican Workshop of Particles and Field, Merida Yuc. M\'ex., Nov. 199

On the intrinsic charm and the recombination mechanisms in charm hadron production

We study $\Lambda_c^\pm$ production in $pN$ and $\pi^-N$ interactions. Recent experimental data from the SELEX and E791 Collaborations at FNAL provide important information on the production mechanism of charm hadrons. In particular, the production of the $\Lambda_c$ baryon provides a good test of the intrinsic charm and the recombination mechanisms, which have been proposed to explain the so called leading particle effects.Comment: 11 pages, two figures (postscript), late

Fuzzy synchronization of chaotic systems with hidden attractors

Chaotic systems are hard to synchronize, and no general solution exists. The presence of hidden attractors makes finding a solution particularly elusive. Successful synchronization critically depends on the control strategy, which must be carefully chosen considering system features such as the presence of hidden attractors. We studied the feasibility of fuzzy control for synchronizing chaotic systems with hidden attractors and employed a special numerical integration method that takes advantage of the oscillatory characteristic of chaotic systems. We hypothesized that fuzzy synchronization and the chosen numerical integration method can successfully deal with this case of synchronization. We tested two synchronization schemes: complete synchronization, which leverages linearization, and projective synchronization, capitalizing on parallel distributed compensation (PDC). We applied the proposal to a set of known chaotic systems of integer order with hidden attractors. Our results indicated that fuzzy control strategies combined with the special numerical integration method are effective tools to synchronize chaotic systems with hidden attractors. In addition, for projective synchronization, we propose a new strategy to optimize error convergence. Furthermore, we tested and compared different Takagi-Sugeno (T-S) fuzzy models obtained by tensor product (TP) model transformation. We found an effect of the fuzzy model of the chaotic system on the synchronization performance

Temporal profiles of intra- and extracellular laccase isoenzymes from Pleurotus ostreatus produced in submerged and solid-state cultures

Laccases are enzymes that have a great potential for use in breaking down toxic compounds. Fungal laccases show high enzymatic activity, especially those produced by basidiomycetes. Depending on the culture conditions and the strain used, a variety of isoenzymes and/or enzymatic activities can be obtained. In this study, extracellular laccase enzymes produced by Pleurotus ostreatus was identified in a submerged culture (SmF), with and without copper sulphate as a chemical inducer, and in a solidstate culture (SSF), using wheat straw as natural inducer. This study was conducted to observe the expression of the enzymes produced under the culture conditions tested and their persistence during the culture, as well as the extracellular activity produced and the correspondence that the isoenzymes presented between the intracellular and extracellular media. A positive effect of the inducers on the specific laccase activity was observed either in SmF with copper sulphate or SSF (41.11 and 40.43 UI/mg protein, respectively), compared with that obtained in SmF without copper sulphate (2.87 UI/mg protein). This effect was different only at the time when the highest activity appeared (360 and 120 h, respectively), showing advantages in SSF. The same three isoenzymes were observed in the three kinds of cultures. The main differences among the laccase profiles reside in the time when they appeared in each culture and only an additional form of lower molecular weight was observed in SSF. The laccase enzymes in the intracellular extracts were equal to those in the extracellular ones. The laccase isoenzymes profiles suggest that the presence of inducers helps in maintaining the activity through the culture time.Keywords: Phenol oxidases, basidiomycete, enzymatic activity, copper, wheat straw, solid-state culture (SSF), submerged culture (SMF