Search results for "block"
showing 10 items of 1177 documents
Intracellular Na+ concentration influences short-term plasticity of glutamate transporter-mediated currents in neocortical astrocytes.
2012
Fast synaptic transmission requires a rapid clearance of the released neurotransmitter from the extracellular space. Glial glutamate transporters (excitatory amino acid transporters, EAATs) strongly contribute to glutamate removal. In this work, we investigated the paired-pulse plasticity of synaptically activated, glutamate transporter-mediated currents (STCs) in cortical layer 2/3 astrocytes. STCs were elicited by local electrical stimulation in layer 4 in the presence of ionotropic glutamate (AMPA and NMDA), GABAA, and GABAB receptor antagonists. In experiments with low [Na+]i (5 mM) intrapipette solution, STCs elicited by paired-pulse stimulation demonstrated paired-pulse facilitation (…
Characterizations of {K,s+1}-Potent Matrices and Applications
2012
Recently, situations where a matrix coincides with some of its powers have been studied. This kind of matrices is related to the generalized inverse matrices. On the other hand, it is possible to introduce another class of matrices that involve an involutory matrix, generalizing the well-known idempotent matrix, widely useful in many applications. In this paper, we introduce a new kind of matrices called {K,s+1}-potent, as an extension of the aforementioned ones. First, different properties of {K,s+1}-potent matrices have been developed. Later, the main result developed in this paper is the characterization of this kind of matrices from a spectral point of view, in terms of powers of the ma…
Il “blocco” dei licenziamenti: profili storici e sistematici
2020
Il saggio analizza le recenti disposizioni di legge che hanno introdotto il blocco temporaneo dei licenziamenti economici come misura congiunturale per fronteggiare l’emergenza pandemica. Nella prima parte l’articolo ricostruisce le analoghe misure vigenti in Italia nell’immediato do-poguerra; nella seconda sostiene come il blocco sia conforme al principio di ragionevolezza, in quanto tutela il diritto fondamentale al lavoro senza ……..compromettere totalmente la libera iniziativa economica privata, in quanto accompagnato da misure di vario genere a favore delle imprese (sgravi fiscali, sospensione di pagamenti…). The essay analyses the recent legislative measures introducing the block of ec…
High dynamic resistance elements based on a Josephson junction array
2020
A chain of superconductor–insulator–superconductor junctions based on Al–AlOx–Al nanostructures and fabricated using conventional lift-off lithography techniques was measured at ultra-low temperatures. At zero magnetic field, the low current bias dynamic resistance can reach values of ≈1011 Ω. It was demonstrated that the system can provide a decent quality current biasing circuit, enabling the observation of Coulomb blockade and Bloch oscillations in ultra-narrow Ti nanowires associated with the quantum phase-slip effect.
Localizing quantum phase slips in one-dimensional Josephson junction chains
2013
Published version of an article in the journal: New Journal of Physics. Also available from the publisher at: http://dx.doi.org/10.1088/1367-2630/15/9/095014 Open Access We studied quantum phase-slip (QPS) phenomena in long one-dimensional Josephson junction series arrays with tunable Josephson coupling. These chains were fabricated with as many as 2888 junctions, where one sample had a separately tunable link in the middle of the chain. Measurements were made of the zero-bias resistance, R0, as well as current-voltage characteristics (IVC). The finite R0 is explained by QPS and shows an exponential dependence on with a distinct change in the exponent at R 0 = RQ = h/4e2. When R0 > R Q, the…
Adiabatic transport of Cooper pairs in arrays of Josephson junctions
1999
We have developed a quantitative theory of Cooper pair pumping in gated one-dimensional arrays of Josephson junctions. The pumping accuracy is limited by quantum tunneling of Cooper pairs out of the propagating potential well and by direct supercurrent flow through the array. Both corrections decrease exponentially with the number N of junctions in the array, but give a serious limitation of accuracy for any practical array. The supercurrent at resonant gate voltages decreases with N only as sin(v/N)/N, where v is the Josephson phase difference across the array.
Fabrication of Nb-based superconducting single electron transistor
2003
Abstract We have fabricated Nb/(Al-)AlOx/Nb junctions with a single electron transistor (SET) geometry using conventional e-beam lithographic technique. It was possible to reach a clearly defined superconducting gap of 0.75 meV as measured in the current vs. voltage (I–V) characteristic curve, which corresponds to Tc of 4.6 K . The Josephson coupling energy was comparable to the charging energy, EJ≈Ec=30– 40 μeV .
Improving Karhunen-Loeve based transform coding by using square isometries
2002
We propose, for an image compression system based on the Karhunen-Loeve transform implemented by neural networks, to take into consideration the 8 square isometries of an image block. The proper isometry applied puts the 8*8 square image block in a standard position, before applying the image block as input to the neural network architecture. The standard position is defined based on the variance of its four 4*4 sub-blocks (quadro partitioned) and brings the sub-block having the greatest variance in a specific corner and in another specific adjoining corner the sub-block having the second variance (if this is not possible the third is considered). The use of this "preprocessing" phase was e…
Differential role of p38 mitogen activated protein kinase for cellular recovery from attack by pore-forming S. aureus alpha-toxin or streptolysin O.
2006
Following the observation that cells are able to recover from membrane lesions incurred by Staphylococcus aureus alpha-toxin and streptolysin O (SLO), we investigated the role of p38 in this process. p38 phosphorylation occurred in response to attack by both toxins, commencing within minutes after toxin treatment and waning after several hours. While SLO reportedly activates p38 via ASK1 and ROS, we show that this pathway does not play a major role for p38 induction in alpha-toxin-treated cells. Strikingly divergent effects of p38 blockade were noted depending on the toxin employed. In the case of alpha-toxin, inhibition of p38 within the time frame of its activation led to disruption of th…