Approximation properties of mixed sampling-Kantorovich operators

AbstractIn the present paper we study the pointwise and uniform convergence properties of a family of multidimensional sampling Kantorovich type operators. Moreover, besides convergence, quantitative estimates and a Voronovskaja type theorem have been established

Variation diminishing-type properties for multivariate sampling Kantorovich operators

In this paper we establish a variation-diminishing type estimate for the multivariate Kantorovich sampling operators with respect to the concept of multidimensional variation introduced by Tonelli. A sharper estimate can be achieved when step functions with compact support (digital images) are considered. Several examples of kernels have been presented

ЗАСТОСУВАННЯ В СХЕМАХ ЗБАГАЧЕННЯ ТОНКОПОДРІБНЕНОЇ СИРОВИНИ УДОСКОНАЛЕНОГО МАГНІТНОГО ГІДРОЦИКЛОНУ

Проблема та її зв'язок з науковими і практичними задачами. Необхідна ступінь подрібнення руди перед її переробленням визначається характером вкраплення рудних мінералів, використанням різних методів збагачення сиро-вини, вимогами до якості концентратів, послідовністю технологічних процесів, що застосовуються у схемах переробки корисних копалин. Чим тонше кінцева крупність подрібнення руди, тим менше залишається мінеральних зростків і тим більше вірогідність отримання якісних концентратів

Speciation of trace elements in human serum by micro anion exchange chromatography coupled with inductively coupled plasma mass spectrometry

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Inducers of Senescence, Toxic Compounds, and Senolytics: The Multiple Faces of Nrf2-Activating Phytochemicals in Cancer Adjuvant Therapy

The reactivation of senescence in cancer and the subsequent clearance of senescent cells are suggested as therapeutic intervention in the eradication of cancer. Several natural compounds that activate Nrf2 (nuclear factor erythroid-derived 2-related factor 2) pathway, which is involved in complex cytoprotective responses, have been paradoxically shown to induce cell death or senescence in cancer. Promoting the cytoprotective Nrf2 pathway may be desirable for chemoprevention, but it might be detrimental in later stages and advanced cancers. However, senolytic activity shown by some Nrf2-activating compounds could be used to target senescent cancer cells (particularly in aged immune-depressed organisms) that escape immunosurveillance. We herein describe in vitro and in vivo effects of fifteen Nrf2-interacting natural compounds (tocotrienols, curcumin, epigallocatechin gallate, quercetin, genistein, resveratrol, silybin, phenethyl isothiocyanate, sulforaphane, triptolide, allicin, berberine, piperlongumine, fisetin, and phloretin) on cellular senescence and discuss their use in adjuvant cancer therapy. In light of available literature, it can be concluded that the meaning and the potential of adjuvant therapy with natural compounds in humans remain unclear, also taking into account the existence of few clinical trials mostly characterized by uncertain results. Further studies are needed to investigate the therapeutic potential of those compounds that display senolytic activity

Zinc-bound metallothioneins and immune plasticity: lessons from very old mice and humans

The capacity of the remodelling immune responses during stress (named immune plasticity) is fundamental to reach successful ageing. We herein report two pivotal experimental models in order to demonstrate the relevance of the immune plasticity in ageing and successful ageing. These two experimental models will be compared with the capacity in remodelling the immune response in human centenarians. With regard to experimental models, one model is represented by the circadian rhythms of immune responses, the other one is the immune responses during partial hepatectomy/liver regeneration (pHx). The latter is suggestive because it mimics the immunosenescence and chronic inflammation 48 h after partial hepatectomy in the young through the continuous production of IL-6, which is the main cause of immune plasticity lack in ageing. The constant production of IL-6 leads to abnormal increments of zinc-bound Metallothionein (MT), which is in turn unable in zinc release in ageing. As a consequence, low zinc ion bioavailability appears for thymic and extrathymic immune efficiency, in particular of liver NKT cells bearing TCR γδ. The remodelling during the circadian cycle and during pHx of zinc-bound MT confers the immune plasticity of liver NKT γδ cells and NK cells in young and very old mice, not in old mice. With regard to human centenarians and their capacity in remodelling the immune response with respect to elderly, these exceptional individuals display low zinc-bound MT associated with: a) satisfactory intracellular zinc ion availability, b) more capacity in zinc release by MT, c) less inflammation due to low gene expression of IL-6 receptor (gp130), d) increased levels of IFN-gamma and number of NKT cell bearing TCR γδ. Moreover, some polymorphisms for MT tested in PBMCs from human donors are related to successful ageing. In conclusion, zinc-bound MT homeostasis is fundamental to confer the immune plasticity that is a condition "sine qua non" to achieve healthy ageing and longevity

A characterization of the convergence in variation for the generalized sampling series

In this paper, we study the convergence in variation for the generalized sampling operators based upon averaged-type kernels and we obtain a characterization of absolutely continuous functions. This result is proved exploiting a relation between the first derivative of the above operator acting on $f$ and the sampling Kantorovich series of f'. By such approach, also a variation detracting-type property is established. Finally, examples of averaged kernels are provided, such as the central B-splines of order $n$ (duration limited functions) or other families of kernels generated by the Fejer and the Bochner-Riesz kernels (bandlimited functions).Comment: 18 pages, 6 figure