1,690 research outputs found
The nucleotide and partial amino acid sequences of rat fetuin
Fetuins are among the major plasma proteins, yet their biological role has remained elusive. Here we report the molecular cloning of rat fetuin and the sequence analysis of a full-length clone, RF619 of 1456 bp with an open reading frame of 1056 bp encoding 352 amino acid residues. The coding part of RF619 was identical with the cDNA sequence of the natural inhibitor of the insulin receptor tyrosine kinase from rat (pp63) except for four substitutions and a single base insertion causing divergence of the predicted protein sequences. Partial amino acid sequences of rat plasma fetuin were in agreement with the predictions based on the RF619 cDNA. Purified rat fetuin inhibited the insulin receptor tyrosine kinase in vitro. Therefore, we conclude that RF619 and pp63 cDNA encode the same protein, i.e. authentic rat fetuin which is a functional tyrosine kinase inhibitor
De novo DNA methylation controls neuronal maturation during adult hippocampal neurogenesis
Adult neurogenesis enables the life-long addition of functional neurons to the hippocampus and is regulated by both cell-intrinsic molecular programs and behavioral activity. De novo DNA methylation is crucial for embryonic brain development, but its role during adult hippocampal neurogenesis has remained unknown. Here, we show that de novo DNA methylation is critical for maturation and functional integration of adult-born neurons in the mouse hippocampus. Bisulfite sequencing revealed that de novo DNA methyltransferases target neuronal enhancers and gene bodies during adult hippocampal neural stem cell differentiation, to establish neuronal methylomes and facilitate transcriptional up-regulation of neuronal genes. Inducible deletion of both de novo DNA methyltransferases Dnmt3a and Dnmt3b in adult neural stem cells did not affect proliferation or fate specification, but specifically impaired dendritic outgrowth and synaptogenesis of newborn neurons, thereby hampering their functional maturation. Consequently, abolishing de novo DNA methylation modulated activation patterns in the hippocampal circuitry and caused specific deficits in hippocampus-dependent learning and memory. Our results demonstrate that proper establishment of neuronal methylomes during adult neurogenesis is fundamental for hippocampal function
Economic space: On the analysis and interpretation of pottery production and distribution
Ceramics are particularly well suited for investigating general patterns of the distribution of premodern products. Archaeometric methods, used to determine raw materials and production techniques, permit the identification of places of production. The work of the research group presented here pursues two objectives: (i) to investigate the usefulness of portable X-ray fluorescence equipment for the analysis of ceramics and (ii) to identify, interpret and study distribution areas of ceramic products in comparative prospective. The paper discusses key economic concepts, sets out the archaeometric methodology and presents initial results in the context of two examples
Tema Con Variazioni: Quantum Channel Capacity
Channel capacity describes the size of the nearly ideal channels, which can
be obtained from many uses of a given channel, using an optimal error
correcting code. In this paper we collect and compare minor and major
variations in the mathematically precise statements of this idea which have
been put forward in the literature. We show that all the variations considered
lead to equivalent capacity definitions. In particular, it makes no difference
whether one requires mean or maximal errors to go to zero, and it makes no
difference whether errors are required to vanish for any sequence of block
sizes compatible with the rate, or only for one infinite sequence.Comment: 32 pages, uses iopart.cl
Pseudo-single crystal electrochemistry on polycrystalline electrodes : visualizing activity at grains and grain boundaries on platinum for the Fe2+/Fe3+ redox reaction
The influence of electrode surface structure on electrochemical reaction rates and mechanisms is a major theme in electrochemical research, especially as electrodes with inherent structural heterogeneities are used ubiquitously. Yet, probing local electrochemistry and surface structure at complex surfaces is challenging. In this paper, high spatial resolution scanning electrochemical cell microscopy (SECCM) complemented with electron backscatter diffraction (EBSD) is demonstrated as a means of performing ‘pseudo-single-crystal’ electrochemical measurements at individual grains of a polycrystalline platinum electrode, while also allowing grain boundaries to be probed. Using the Fe2+/3+ couple as an illustrative case, a strong correlation is found between local surface structure and electrochemical activity. Variations in electrochemical activity for individual high index grains, visualized in a weakly adsorbing perchlorate medium, show that there is higher activity on grains with a significant (101) orientation contribution, compared to those with (001) and (111) contribution, consistent with findings on single-crystal electrodes. Interestingly, for Fe2+ oxidation in a sulfate medium a different pattern of activity emerges. Here, SECCM reveals only minor variations in activity between individual grains, again consistent with single-crystal studies, with a greatly enhanced activity at grain boundaries. This suggests that these sites may contribute significantly to the overall electrochemical behavior measured on the macroscale
Entropy and Quantum Kolmogorov Complexity: A Quantum Brudno's Theorem
In classical information theory, entropy rate and Kolmogorov complexity per
symbol are related by a theorem of Brudno. In this paper, we prove a quantum
version of this theorem, connecting the von Neumann entropy rate and two
notions of quantum Kolmogorov complexity, both based on the shortest qubit
descriptions of qubit strings that, run by a universal quantum Turing machine,
reproduce them as outputs.Comment: 26 pages, no figures. Reference to publication added: published in
the Communications in Mathematical Physics
(http://www.springerlink.com/content/1432-0916/
Consumer price indexes: an analysis of heterogeneity across sub-populations
La rilevanza dell'Indece dei Prezzi al Consumo quale misura dell'inflazione è stata a lungo dibattuta in particolare esminando le differenti cause di distorsione dovute all'utilizzo di un paniere fisso di beni e servizi. Di conseguenza la letteratura ha proposto indici dei prezzi sperimentali per particolari sottogruppi di popolazioni. tali indici hanno rilevanza ai fini della politica economica e sociale, poiché è probabile che differenti gruppi di popolazione abbiano comportamenti nei consumi differenti dalla media, ad esempio i consumatori poveri (Garner, Johnson & Kokoski, 1996) e quelli anziani (Stewart, 2008). Lo scopo di questo lavoro è quello di esaminare le possibilità offerte da metodi di costruzione alternativi degli Indici dei Prezzi al Consumo ai fini di cogliere la variabilità dei tassi di inflazione relativi a differenti categorie di consumatori.The soundeness of Consumer Price Indexes (CPI) as a measure of inflation has long been debeate, focusing on the different sources of bias inherent to use of a constant basket of goods and services. Thus experimental consumer price indexes have been proposed for targeted sub-populations specifically relevant for social and economic policy, that are likely to have consumption patterns different from yhe average, i.e poor (Garner, Johnson & Kokoski, 1996) and elderly (Stewart, 2008)houseolds. Aim of this work is to investigate the possibilities offered by alternative methods of construction of consumer price indices in order to capture the variability of inflation rates facing different houseolds' types
Ultrafast All-Polymer Paper-Based Batteries
Conducting polymers for battery applications have been subject to numerous investigations during the last two decades. However, the functional charging rates and the cycling stabilities have so far been found to be insufficient for practical applications. These shortcomings can, at least partially, be explained by the fact that thick layers of the conducting polymers have been used to obtain sufficient capacities of the batteries. In the present letter, we introduce a novel nanostructured high-surface area electrode material for energy storage applications composed of cellulose fibers of algal origin individually coated with a 50 nm thin layer of polypyrrole. Our results show the hitherto highest reported charge capacities and charging rates for an all polymer paper-based battery. The composite conductive paper material is shown to have a specific surface area of 80 m2 g-1 and batteries based on this material can be charged with currents as high as 600 mA cm-2 with only 6 % loss in capacity over 100 subsequent charge and discharge cycles. The aqueous-based batteries, which are entirely based on cellulose and polypyrrole and exhibit charge capacities between 25 and 33 mAh g-1 or 38-50 mAh g-1 per weight of the active material, open up new possibilities for the production of environmentally friendly, cost efficient, up-scalable and lightweight energy storage systems. There is currently a great interest in the development of thin, flexible, lightweight, and environmentally friendly batteries and supercapacitors.1 In this process, the preparation of novel redox polymer and electronically conducting polymer-base
Mobile kinks and half-integer zero-field-like steps in highly discrete alternating Josephson junction arrays
The dynamics of a one-dimensional, highly discrete, linear array of
alternating and Josephson junctions is studied numerically, under
constant bias current at zero magnetic field. The calculated current - voltage
characteristics exhibit half-integer and integer zero-field-like steps for even
and odd total number of junctions, respectively. Inspection of the
instantaneous phases reveals that, in the former case, single kink
excitations (discrete semi-fluxons) are supported, whose propagation in the
array gives rise to the step, while in the latter case, a pair of
kink -- antikink appears, whose propagation gives rise to the
step. When additional kinks are inserted in the array, they are
subjected to fractionalization, transforming themselves into two closely spaced
kinks. As they propagate in the array along with the single kink or
the kink - antikink pair, they give rise to higher half-integer or
integer zero-field-like steps, respectively.Comment: 7 pages, 8 figures, submitted to Supercond. Sci. Techno
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