Experimental analysis of transverse intermittency in a turbulent jet flow

The statistical properties of the velocity differences are experimentally investigated in a turbulent jet-flow at moderate Re _λ by X-probe hot wire anemometry measurements. It is found that the traverse velocity components show a more intermittent behavior with respect to the longitudinal ones. This result is obtained by the analysis of the longitudinal and transverse intermittency exponents measured by the Extended Self-Similarity form of scaling, and by the comparison of the longitudinal and transverse velocity difference Probability Distribution Functions. Received: 25 March 1996/Accepted: 15 August 1996     

Inverse Variational Inequality Approach and Applications

It is well known that a dynamic oligopolistic market equilibrium problem can be studied as an evolutionary variational inequality and this problem is approached as a problem of profit optimization for the firms. On the contrary, in this article, with the help of an inverse variational formulation, the behavior of control policies for an oligopolistic market equilibrium problem, whose aim is to regulate the exportation through the adjustment of taxes on the firms, is studied. This is considered as a policymaker optimization problem. More precisely, a definition of equilibrium for the firms by using the Lagrange multipliers is provided together to the optimal regulatory tax definition. Moreover an existence result is given and, at last, a numerical example is analyzed.     

An estimate of the contribution to the cross section due to the break-up of a trapped complex in the reaction of S on Co and S on Ge

This paper deals with the contribution to the reaction cross section coming from the break-up of an interacting complex of two fragments which is trapped in a pocket of the relative potential acting between the fragments. Calculations for the systems S on Co and S on Ge are done by using the semi-classical expression of tunneling through the barrier and the statistical break-up probability. The results are discussed and conclusions about the reaction mechanism are drawn.     

A global existence and uniqueness result for a class of hyperbolic operators

In this paper a global existence and uniqueness theorem for the Cauchy problem related to the class of hyperbolic operators with double characteristics \(P=D^2_{t} - D^2_{x_1} - (t+ \lambda - \alpha (x_1))^2 D^2_{x_2},\) depending on the parameter \(\lambda \) in the half-space \(\Omega = \mathbb {R}^2 \times ]0, + \infty [\) is proved. In the first part of the paper, a priori estimates in Sobolev spaces \(W^{r,2}\), with \(r\) negative, have been established. Then, the regularity is studied by using these spaces and by constructing a Green’s function in the half-plane for the operator of the waves.     

Identification and structural characterization by LC-ESI-IONTRAP and LC-ESI-TOF of some metabolic conjugation products of homovanillic acid in urine of neuroblastoma patients

The levels of urinary catecholamine metabolites, such as homovanillic acid (HVA) and vanillylmandelic acid, are routinely used as a clinical tool in the diagnosis and follow-up of neuroblastoma (NB) patients. Recently, in the Clinical Pathology Laboratory Unit of G. Gaslini Children Hospital, a commercial method that employs liquid chromatography coupled to electrochemical detection (LC-EC) has been introduced for the measurement of these metabolites in the routine laboratory practice. Using this LC-EC method, an unknown peak could be observed only in samples derived from NB patients. To investigate the nature of this peak, we used a combination of liquid chromatography-time-of-flight mass spectrometry (LC-TOF-MS) and liquid chromatography-ion trap tandem mass spectrometry (LC-IT-MS). The first approach was used to obtain the elemental composition of the ions present in this new signal. To get additional structural information useful for the elucidation of unknown compounds, the ion trap analyzer was exploited. We were able to identify not just one, but three unknown signals in urine samples from NB patients which corresponded to three conjugated products of HVA: HVA sulfate and two glucuronoconjugate isomers. The enzymatic hydrolysis with β-glucuronidase confirmed the proposed structures, while the selective alkaline hydrolysis allowed us to distinguish the difference between phenol- and acyl-glucuronide of HVA. The latter was the unknown peak observed in LC-EC separations of urine samples from NB patients.     

The Role of Resveratrol in Human Male Fertility

Resveratrol (RSV) (3,4′,5 trihydroxystilbene) is a natural non-flavonoid polyphenol widely present in the Mediterranean diet. In particular, RSV is found in grapes, peanuts, berries, and red wine. Many beneficial effects of this molecule on human health have been reported. In fact, it improves some clinical aspects of various diseases, such as obesity, tumors, hypertension, Alzheimer’s disease, stroke, cardiovascular diseases, and diabetes mellitus. However, little is known about the relationship between this compound and male fertility and the few available results are often controversial. Therefore, this review evaluated the effects of RSV on human male fertility and the mechanisms through which this polyphenol could act on human spermatozoa.