Search results for "4a"

Fourier analysis of periodic Radon transforms

2019

We study reconstruction of an unknown function from its $d$-plane Radon transform on the flat $n$-torus when $1 \leq d \leq n-1$. We prove new reconstruction formulas and stability results with respect to weighted Bessel potential norms. We solve the associated Tikhonov minimization problem on $H^s$ Sobolev spaces using the properties of the adjoint and normal operators. One of the inversion formulas implies that a compactly supported distribution on the plane with zero average is a weighted sum of its X-ray data.

Selective versions of chain condition-type properties

2015

We study selective and game-theoretic versions of properties like the ccc, weak Lindel\"ofness and separability, giving various characterizations of them and exploring connections between these properties and some classical cardinal invariants of the continuum.

An experimental study of a refrigerating plant when replacing R22 with HFCs refrigerants

2011

This paper presents the results of an experimental analysis comparing the performance of a vapour compression refrigerating unit operating with R22, and its performance in comparison to some HFCs fluids, substituting the former according to reg. n. 2037/2000. In particular, the plant working efficiency was first tested with R22 and then with three HFC fluids: R417A, R407C and R404A. The investigation verified that the performance with HFCs refrigerants did not result as efficient as when using R22. An environmental analysis also was performed.

Nonlinear multivalued Duffing systems

2018

We consider a multivalued nonlinear Duffing system driven by a nonlinear nonhomogeneous differential operator. We prove existence theorems for both the convex and nonconvex problems (according to whether the multivalued perturbation is convex valued or not). Also, we show that the solutions of the nonconvex problem are dense in those of the convex (relaxation theorem). Our work extends the recent one by Kalita-Kowalski (JMAA, https://doi.org/10.1016/j.jmaa. 2018.01.067).

Generalized Entropies, Variance and Applications

2020

The generalized cumulative residual entropy is a recently defined dispersion measure. In this paper, we obtain some further results for such a measure, in relation to the generalized cumulative residual entropy and the variance of random lifetimes. We show that it has an intimate connection with the non-homogeneous Poisson process. We also get new expressions, bounds and stochastic comparisons involving such measures. Moreover, the dynamic version of the mentioned notions is studied through the residual lifetimes and suitable aging notions. In this framework we achieve some findings of interest in reliability theory, such as a characterization for the exponential distribution, various resul…

Rapid and Standardized Quantitation of Hemolytic Activity of the Fourth Component of Human Complement

1990

Based on a method that uses the fourth component of complement (C4)-deficient guinea pig serum to quantify the hemolytic activity of C4, we developed an assay that allows the processing of a large number of individual samples with high reproducibility. In contrast to the conventional procedure using titration curves of each sample to be determined, we can show that a single appropriate dilution of the sample allows accurate quantitation of hemolytic activity. The reliability of the procedure is demonstrated using either C4A- or C4B- deficient and normal individual samples.

DNA damage causes TP53-dependent coupling of self-renewal and senescence pathways in embryonal carcinoma cells.

2013

Recent studies have highlighted an apparently paradoxical link between self-renewal and senescence triggered by DNA damage in certain cell types. In addition, the finding that TP53 can suppress senescence has caused a re-evaluation of its functional role in regulating these outcomes. To investigate these phenomena and their relationship to pluripotency and senescence, we examined the response of the TP53-competent embryonal carcinoma (EC) cell line PA-1 to etoposide-induced DNA damage. Nuclear POU5F1/OCT4A and P21CIP1 were upregulated in the same cells following etoposide-induced G 2M arrest. However, while accumulating in the karyosol, the amount of OCT4A was reduced in the chromatin fract…

On the order of indeterminate moment problems

2013

For an indeterminate moment problem we denote the orthonormal polynomials by P_n. We study the relation between the growth of the function P(z)=(\sum_{n=0}^\infty|P_n(z)|^2)^{1/2} and summability properties of the sequence (P_n(z)). Under certain assumptions on the recurrence coefficients from the three term recurrence relation zP_n(z)=b_nP_{n+1}(z)+a_nP_n(z)+b_{n-1}P_{n-1}(z), we show that the function P is of order \alpha with 0<\alpha<1, if and only if the sequence (P_n(z)) is absolutely summable to any power greater than 2\alpha. Furthermore, the order \alpha is equal to the exponent of convergence of the sequence (b_n). Similar results are obtained for logarithmic order and for more ge…

The tumor suppressor p14ARF hampers proliferation of aneuploid cells induced by CENP-E partial depletion

The Spindle Assembly Checkpoint (SAC) is a cellular surveillance mechanism that ensures faithfully segregation of chromosomes. Reduced expression of some of its components weakens the SAC and induces chromosome instability and aneuploidy, both hallmarks of tumor cells. Centromere Protein-E (CENP-E) is a crucial component of the SAC and facilitates kinetochore microtubule attachment required to achieve and maintain chromosome alignment. To investigate the possible role of p14ARF on aneuploid cells proliferation we induced aneuploidy in primary human fibroblasts (IMR90) and in near diploid tumor cells (HCT116) by partial depletion of CENP-E obtained by RNA interference. Our results show that …

MECHANISMS OF CHROMOSOMAL INSTABILITY: RELATIONSHIP BETWEEN TUMOR SUPPRESSORS AND SAC GENES

2017

Caratteristica comune di molti tumori solidi è l’aneuploidia, conseguenza dell’instabilità cromosomica (CIN). Tuttavia non sono ancora chiari i meccanismi alla base dell’aneuploidia e i percorsi che permettono la sua tolleranza. Lo Spindle Assembly Checkpoint (SAC) è un meccanismo di sorveglianza cellulare che controlla la stabilità genomica durante la mitosi. Alterazioni nei membri del SAC generano aneuploidia, ma non è ancora chiaro se questi difetti sono sufficienti per promuovere la tumori-genesi. In questo processo, infatti, il contesto genetico della cellula gioca un ruolo importante. È risaputo che i difetti di p53 aiutano le cellule a proliferare velocemente tollerando la CIN. Al co…