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  • Author: Francesca Messina x
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Abstract.

We prove uniqueness and continuous dependence results for a severely ill-posed linear integrodifferential boundary-value parabolic problem with no initial condition. This latter condition is replaced with an additional boundary information prescribing the temperature on an open subset of the geometric domain article image.

The integral operators entering the equation are defined by integrals of Volterra type with respect to time. In particular, the class of integrodifferential equations dealt with in this paper include those occurring in the linear theory of heat flow in a rigid body consisting of a material with thermal memory.

Abstract

The aim of the present paper is to generalize the results in [Denisov, J. Inverse Ill-Posed Probl. 16: 837–848, 2008.] devoted to a one-dimensional semilinear wave equation and consisting of recovering a time-dependent function α representing the transformed argument. More exactly: (i) we will deal with a general semilinear integro-differential hyperbolic d-dimensional equation in divergence form (d = 1, 2, 3); (ii) the space-time set considered here is a smooth cylinder where surface boundary conditions are prescribed; (iii) the term with transformed arguments is allowed to contain integral operators; (iv) the additional information is of integral type.

The existence and uniqueness results for our specific problem are deduced as consequences of similar results for an operator integro-differential identification problem in a Hilbert space.

Abstract.

Via Carleman estimates we determine sufficient conditions ensuring uniqueness and continuous dependence results for a severely ill-posed linear integro-differential boundary-value parabolic problem with no initial condition. This latter condition is replaced with an additional boundary information prescribing the temperature on an open subset of the geometric domain .

The integral operators entering the equation are defined by integrals of Volterra type with respect to time.

Abstract

48, XXYY is a very rare sex chromosome aneuploidy, characterized by both an extra X and Y chromosome with a prevalence of 1:18,000–1:40,000. Most patients are diagnosed prenatally by cytogenetic examination of amniotic fluid, or during the first years of life because of severe developmental delay, cognitive impairment and behavioural disorders. This syndrome shares two findings with Klinefelter syndrome, namely tall stature and hypergonadotropic hypogonadism but at this time no genital anomalies have been reported in patients with this tetrasomy. We describe a 48, XXYY neonate and a clinical picture characterized by small penis, bifid scrotum, scrotal hypospadias and testes palpable in the labioscrotal folds.

Abstract

Objective: Primary gonadal failure may occur in most individuals with Turner syndrome (TS). Since ovaries in TS girls undergo premature apoptosis and cryopreservation of ovarian tissue is now feasible, it would be useful to identify a reliable marker of ovarian reserve in these patients. We planned to evaluate ovarian function in a group of TS patients by measuring both traditional markers and inhibin B and to compare these results with those of a control group.

Study design: We enrolled 23 patients with TS and 17 age-matched healthy girls. The median age of our TS patients was 17.6 years. Three out of the 23 patients (13%) showed spontaneous pubertal development and regular menstrual cycles; the remaining 20 (86.9%) presented with primary amenorrhea.

Results: The median level of inhibin B in the TS patients with primary amenorrhea was 42 pg/mL and did not differ significantly among the different subgroups in relation to karyotype. The median inhibin B level in the control group was significantly higher than in the TS girls with primary amenorrhea (83 vs. 42 pg/mL, p<0.00001). In the three patients with TS and spontaneous menstrual cycles, the inhibin B levels were significantly higher when compared to the values of the TS girls with primary amenorrhea.

Conclusion: TS patients with primary amenorrhea have significantly lower levels of inhibin B than TS girls with spontaneous puberty and healthy controls. Inhibin B does not correlate with follicle-stimulating hormone/luteinizing hormone. If our results are confirmed in further studies, inhibin B could become a first-line screening test for assessing ovarian reserve and a longitudinal marker of the possible decline of ovarian function in TS.

Abstract

General diffusion porins are passive transmembrane channels. We have explored the possibility to create artificial nanopores starting from natural β-barrel structures. Structural elements of bacterial porins were used to build a series of artificial nanopores. The basic module was selected by multi-alignment of general diffusion porins. The sequence corresponded to a highly conserved motif containing two β-strands, which was obtained from Escherichia coli OmpF. Dimeric to octameric repeats were obtained through cDNA recombinant technology. The hexameric repeat was used to test its properties. This protein was expressed, purified and reconstituted in the planar bilayer membranes. It was able to form channels in membranes with a conductance of 300 pS in 150 mm KCl and did not show any relevant voltage-dependence.