Low-energy random number generation is critical for many emerging computing schemes proposed to complement or replace von Neumann architectures. However, current random number generators are always associated with an energy cost that is prohibitive for these computing schemes. In this paper, we introduce random number bit generation based on specific nanodevices: superparamagnetic tunnel junctions. We experimentally demonstrate high quality random bit generation that represents orders-of-magnitude improvements in energy efficiency compared to current solutions. We show that the random generation speed improves with nanodevice scaling, and investigate the impact of temperature, magnetic field and crosstalk. Finally, we show how alternative computing schemes can be implemented using superparamagentic tunnel junctions as random number generators. These results open the way for fabricating efficient hardware computing devices leveraging stochasticity, and highlight a novel use for emerging nanodevices.
In a previous publication, the authors described the establishment of a working system for studing effects of factors involved in the chemical nature of a microcarrier on cell attachment, spreading, and growth. The first part of the rsearch dealt with the influence of the type and amount of the positively charged groups. In the present article, the authors will describe the effect of the introduction of hydrophobic elements onto primary amino derivatized polyacrylamide microcariers. It was found that cell attachement kinetics were gradually enhanced in parallel to a gradual increase in hydrophobicity via elongation of the hydrocarbon side-chain carrying the primary amino charged group. A threshold effect of the amount of charge required for cell attachment spreading and growth was exhibited on all the tested primary amino derivatized microcarriers. Optimum cell growth was recorded for the butylamine and hexylamine polyacrylamide microcarris. Lowre cell yields were recorded for ethylamine and octylamine derivatives. The location of the introduced hydrophobic element has a profound effect on cell propagation. Introduction of hydrophobicity onto the polymeric backbone of the microcarrier (via copolymerization of hydrophobic comonomer) lead to negative influence on cell attachement and growth yields. Out of the series of derivatized polyacrylamide microcarriers tested, it seems that the hexylamine derivative may be a potential alternative for the commonly used tertiary amine microcariers.
The high incidence of viral infections in patients with lymphocytic leukemia is well documented, but the role played by interferon in the pathogenesis of such infections is not known. In this study, we investigated the possibility that gamma (gamma) interferon production, induced by phytohemagglutinin (PHA) might be impaired in leukocytes from patients with acute lymphocytic leukemia (ALL). We also compared this response with alpha (alpha) interferon production, and with PHA-stimulated lymphocyte transformation. We have shown that the gamma interferon response of leukocytes from patients, both in relapse and in remission, was markedly lower than in leukocytes from normal donors. However, the alpha interferon response in leukocytes from the patients was normal. In contrast the defective gamma interferon response to PHA stimulation of cells from patients in remission, lymphocyte transformation by PHA was normal. Lymphocytes from patients in relapse has a delayed response. Our findings suggest (1) that the defective gamma interferon response which occurs in cells from patients with ALL, both in relapse and remission, contributes to increased susceptibility to viral infections, (2) that alpha interferon may not be the optimal type of interferon for treatment of certain viral infections, and (3) that different triggering mechanisms, or different receptors, exist for PHA-induced gamma interferon production and for lymphocyte transformation in cells of patients with ALL.
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