1-Meixner Random Vectors

Journal of Theoretical Probability - A definition of d-dimensional n-Meixner random vectors is given first. This definition involves the commutators of their semi-quantum operators. After that we...     

Neon scattering off Sodium clusters at finite temperatures

We present findings from computer simulations of collisions of neon atomic beams with Na20 atomic clusters at different internal temperatures. A functional form for the double differential cross section is determined, and no simple signature of a phase transition is seen, even though the clusters undergo a melting phase transition in the temperature range investigated (100 K–400 K). However, such experiments can be used effectively to measure the internal cluster temperature.     

Monitoring the packet gap of real-time packet traffic

Real-time packet traffic is characterized by a strict deadline on the end-to-end time delay and an upper bound on the information loss. Due to the high correlation among consecutive packets, the individual packet loss does not well characterize the performance of real-time packet sessions. An additional measure of packet loss is necessary to adequately assess the quality of each real-time connection. The additional measure considered here is the average number of consecutively lost packets, also called the average packet gap. We derive a closed form for the average packet gap for the multiclassG/G/m/B queueing system in equilibrium and show that it only depends on the loss behavior of two consecutive packets. This result considerably simplifies the monitoring process of real-time packet traffic sessions. If the packet loss process is markovian, the consecutive packet loss has a geometric distribution.     

Ultrashort pulse laser osteotomy

Laser treatment of bone tissue has already been the subject of many studies to find substitutes for mechanical instruments that are nowadays used in implantology and orthopaedics. Mainly lasers with pulse durations in the μs region have been tested leaving surface features that are not always satisfactory. Therefore, in the present study laser osteotomy has been performed with a 330 fs Yb:glass laser, λ = 1040 nm, at a pulse repetition rate of 1 kHz. For bovine spongiosa, compacta, and cartilage, the ablation thresholds as well as the ablation rates for various pulse energies have been determined. Additionally, quadratic areas have been ablated in bone tissue. The remaining morphology has been analyzed via scanning electron microscopy. Laser ablation has also been performed with an Er, Cr:YSGG laser, λ = 2780 nm, PRR = 20 Hz, τ ～ 50 μs. The results of USPL and Erbium laser ablation are compared.     

Synthesis of pyridyl- and quinolyl-substituted 2-aminothiazoles

Five 2-amino-4-(x-pyridyl)- and 2-amino-4-(x-quinolyl)thiazoles have been synthesized by the condensation of thiourea with bromoacetylpyridines and -quinolines. The reaction of pyridyl pyridylmethyl ketones with thiourea and halogens produced four 2-aminothiazoles possessing pyridyl substituents in 4- and 5-positions on the thiazole ring. Treatment of N-(3-pyridyl)- and N-(3-quinoiyl)thiourea with α-bromoketones gave seven new 2-(3-pyridyl)amino- and 2-(3-quinolyl)aminothiazoles. The ultraviolet spectra of the pyridyl- and quinolyl- substituted 2-aminothiazoles were recorded.     

Synthesis of bicyclic pyrimidine derivatives as ATP analogues

A highly efficient and general solid-phase synthesis of bicyclic pyrimidine derivatives that target purine dependent proteins is reported. The synthesis of the key intermediate, 4,6-disubstituted-5-amino-pyrimidine, involved reduction of the corresponding nitro derivatives using 1,1'-dioctyl-viologen in a triphasic milieu. The mild reduction conditions enable the use of any acid labile solid support as well as a wide range of combinatorial substituents, thus enabling the synthesis of large libraries of highly diverse bicyclic pyrimidines. Alternative reduction conditions with tin(II) chloride and structure-reactivity studies are discussed as well.     

Study of thermal behaviour of some edible mushrooms

This paper is aimed to analyse the thermal behaviour in air of edible mushrooms through nonisothermal (TG, DTG, DTA) and calorimetric (Berthelot calorimeter) methods. The studied mushrooms were Pleurotus ostreatus spontaneously grown and from culture and Agaricus bisporus from culture, currently used in alimentation but insufficiently investigated from this point of view. The analysis of TG–DTG–DTA curves has indicated that the degradation mechanism is complex and characteristic to every species and major differences between the cap and the stipe of investigated mushrooms have not been recorded. These species are thermally stable in the range of 30–160 °C. The thermal stability in terms of initial degradation temperature (T _i °C) and the temperature corresponding to the conversion grade (T _α=0.03 °C) indicate that the stipe has a thermal stability close to the cap one and that the cultivated mushrooms are more thermally stable than those spontaneously grown. The obtained results concerning the combustion of the sample using Berthelot calorimeter are in accordance with the TG–DTG–DTA analysis. The residue obtained is a measure of the mineral content and is quantitatively close.     

Transportation of megawatt millijoule laser pulses via optical fibers?

Laser ignition is considered to be one of the most promising future concepts for internal combustion engines. It combines the legally required reduction of pollutant emissions and higher engine efficiencies. The igniting plasma is generated by a focused pulsed laser beam. Having pulse durations of a few nanoseconds, the pulse energy E _p for reliable ignition amounts to the order of 10 mJ. Different methods of laser ignition with an emphasis on fiber-based systems will be discussed and evaluated.     

Collective oscillations of a trapped fermi gas near the unitary limit

We calculate the oscillation frequencies of trapped Fermi condensate with particular emphasis on the equation of state of the interacting Fermi system. We confirm Stringari's finding that the frequencies are independent of the interaction in the unitary limit, and we extend the theory away from that limit, where the interaction does affect the frequencies of the compressional modes only.     

Stochastic control with exit time and constraints,application to small time attainability of sets

We study the existence of a solution of controlled stochastic differential equations remaining in a given set of constraints at any time smaller than the exit time of a given open set. We also investigate the small time attainability of a given closed set K, i.e., the property that, for all arbitrary small time horizon T and for all initial condition in a sufficiently small neighborhood of K, there exists a solution to the controlled stochastic differential equation which reaches K before T.