134 research outputs found
Josephson oscillation linewidth of ion-irradiated YBaCuO junctions
We report on the noise properties of ion-irradiated YBaCuO
Josephson junctions. This work aims at investigating the linewidth of the
Josephson oscillation with a detector response experiment at 132 GHz.
Experimental results are compared with a simple analytical model based on the
Likharev-Semenov equation and the de Gennes dirty limit approximation. We show
that the main source of low-frequency fluctuations in these junctions is the
broadband Johnson noise and that the excess () noise contribution
does not prevail in the temperature range of interest, as reported in some
other types of high-T superconducting Josephson junctions. Finally, we
discuss the interest of ion-irradiated junctions to implement frequency-tunable
oscillators consisting of synchronized arrays of Josephson junctions
Imprinted MicroRNA Gene Clusters in the Evolution, Development, and Functions of Mammalian Placenta
In mammals, the expression of a subset of microRNA (miRNA) genes is governed by genomic imprinting, an epigenetic mechanism that confers monoallelic expression in a parent-of-origin manner. Three evolutionarily distinct genomic intervals contain the vast majority of imprinted miRNA genes: the rodent-specific, paternally expressed C2MC located in intron 10 of the Sfmbt2 gene, the primate-specific, paternally expressed C19MC positioned at human Chr.19q13.4 and the eutherian-specific, maternally expressed miRNAs embedded within the imprinted Dlk1-Dio3 domains at human 14q32 (also named C14MC in humans). Interestingly, these imprinted miRNA genes form large clusters composed of many related gene copies that are co-expressed with a marked, or even exclusive, localization in the placenta. Here, we summarize our knowledge on the evolutionary, molecular, and physiological relevance of these epigenetically-regulated, recently-evolved miRNAs, by focusing on their roles in placentation and possibly also in pregnancy diseases (e.g., preeclampsia, intrauterine growth restriction, preterm birth)
- âŠ