We have previously identified neutralizing human monoclonal antibodies against Nipah virus (NiV) and Hendra virus (HeV) by panning a large nonimmune antibody library against a soluble form of the HeV ...attachment-envelope glycoprotein G (sGHeV). One of these antibodies, m102, which exhibited the highest level of cross-reactive neutralization of both NiV and HeV G, was affinity maturated by light-chain shuffling combined with random mutagenesis of its heavy-chain variable domain and panning against sGHeV. One of the selected antibody Fab clones, m102.4, had affinity of binding to sGHeV that was equal to or higher than that of the other Fabs; it was converted to IgG1 and tested against infectious NiV and HeV. It exhibited exceptionally potent and cross-reactive inhibitory activity with 50% inhibitory concentrations below 0.04 and 0.6 μg/mL, respectively. The virus-neutralizing activity correlated with the binding affinity of the antibody to sGHeV and sGNiV. m102.4 bound a soluble form of NiV G (sGNiV) better than it bound sGHeV, and it neutralized NiV better than HeV, despite being originally selected against sGHeV. These results suggest that m102.4 has potential as a therapeutic agent for the treatment of diseases caused by henipaviruses. It could be also used for prophylaxis and diagnosis, and as a research reagent
Simulation of actual muscle potentials is necessary to understand processes that underlie changes in electromyographic signals. The work reported aims to analyse existing methods and suggest new ways ...of calculating precisely the signals (MUS) detected by a multielectrode from motor units (MUs) consisting of homogeneous or inhomogeneous (functionally and geometrically) fibres. Simulation (based on cable equations) of intracellular action potential (IAP) in a muscle fibre with a moderate geometrical inhomogeneity demonstrates that considerable changes in propagation velocity (more than 3.5 times) are accompanied by insignificant changes in the IAP amplitude (< 5%) and IAP shape in the temporal domain. MUS can therefore be considered as the output signal of a timeshift-invariant system whose input signal is the first temporal derivative of the IAP. As a result, calculation of MUS is reduced to a single convolution in the case of muscle composed of both homogeneous and inhomogeneous fibres. The suggested approach is valid for simulation of recordings obtained with points or rectangular plates leading off surfaces from muscles consisting of fibres that are parallel or inclined to the skin surface. The MUS terminal phases are prolonged because of fibre inhomogeneities. The presence of geometrical inhomogeneities results in additional positive-negative phases in MUS.
There have been previous hints that the transiting planet WASP-3b is accompanied by a second planet in a nearby orbit, based on small deviations from strict periodicity of the observed transits. Here ...we present 17 precise radial velocity (RV) measurements and 32 transit light curves that were acquired between 2009 and 2011. These data were used to refine the parameters of the host star and transiting planet. This has resulted in reduced uncertainties for the radii and masses of the star and planet. The RV data and the ttansit times show no evidence for an additional planet in the system. Therefore, we have determined the upper limit on the mass of any hypothetical second planet, as a function of its orbital period.
Abstract
The approach for calculating the propagation time of a signal between GPS satellites will be summarized, based on the proposed new theoretical approach in several previous publications, as ...well as the perspectives for future development of the theory. Topics include: 1. Basic notions of inter-satellite communications. 2. Shapiro delay formulae in General Relativity Theory - basic formalism and the necessity to extend the formalism by taking into account the satellite motion on a plane elliptic or space-distributed elliptic orbit. 3. Basic facts about the disturbed motion in celestial mechanics and the necessity to incorporate it in the theory of inter-satellite communications, accounting for General Relativity Effects. 4. Propagation time of a signal, emitted by a satellite on a plane and also space-distributed elliptical orbit in terms of zero-order elliptic integrals and respectively of higher order integrals. Proof of the real-valuedness of the propagation time for all cases as one of the criteria for the correctness of the theoretical approach. 5. New analytical algorithms for calculation of zero-order elliptic integrals in the Legendre form. Relation to two representations in the Weierstrass form. 6. The new formalism of intersecting four-dimensional null cones and the resulting physical notions of the (intersecting)) space-time interval (with the property of being positive, negative or equal to zero) and the (intersecting) geodesic distance (being only positive, because is related to the distance, travelled by light or radio signals). Proof of these properties in the general case and in some partial cases. New numerical estimate
E
lim
> 45.002510943228 deg, above which the space-time interval is positive and thus inter-satellite communications between satellites on one plane elliptical orbit are possible. The angular distance of 45 deg is typical for the disposition of 8 satellites on one orbit in the Russian satellite constellation
GLON ASS
, so it might be claimed that such a configuration is favourable from the point of view of inter-satellite communications (with account of GRT effects).
In this paper, we discuss arithmetic structures based on quantum cellular automata (QCA). By taking advantage of the unique capabilities of QCA we are able to design interesting computational ...architectures. We describe important design considerations and show how addition and multiplication circuits can be implemented using QCADesigner, a QCA design tool which has been developed in our laboratory. QCA technology allows, among other things, the implementation of majority boolean gates and interconnecting "wires" that support cross-overs on the same fabrication level. One of the important challenges with QCA design is working within a different cost function from standard transistor circuits. These differences arise from the device level latching inherent in QCA. This latching makes the total delay of a circuit directly proportional to the maximum number of clocking zones between input and output and the number of gates.
With the ongoing growth in the field of neuro-inspired computing, newly arriving computational architectures demand extensive validation and testing against existing benchmarks to establish their ...competence and value. In our work, we break down the validation step into two parts—(1) establishing a methodological and numerical groundwork to establish a comparison between neuromorphic and conventional platforms and, (2) performing a sensitivity analysis on the obtained model regime to assess its robustness. We study the neuronal dynamics based on the Leaky Integrate and Fire (LIF) model, which is built upon data from the mouse visual cortex spanning a set of anatomical and physiological constraints. Intel Corp.'s first neuromorphic chip “Loihi” serves as our neuromorphic platform and results on it are validated against the classical simulations. After setting up a model that allows a seamless mapping between the Loihi and the classical simulations, we find that Loihi replicates classical simulations very efficiently with high precision. This model is then subjected to the second phase of validation, through sensitivity analysis, by assessing the impact on the cost function as values of the significant model parameters are varied. The work is done in two steps—(1) assessing the impact while changing one parameter at a time, (2) assessing the impact while changing two parameters at a time. We observe that the model is quite robust for majority of the parameters with slight change in the cost function. We also identify a subset of the model parameters changes which make the model more sensitive and thus, need to be defined more precisely.
This paper deals with a study focused on the single point incremental forming (SPIF) of titanium Grade 2 sheets. The direct impact of the sliding velocity of the forming tool on mechanical and ...thermal process loads was experimentally investigated. A wide range of spindle speeds and feed rates were examined at different forming conditions. The developed profiles of the mechanical and thermal demands during the SPIF of titanium sheets are presented and discussed. Forming temperature and force were directly related to the tool rotation speed, higher temperatures and lower reactional forces correspond to higher speeds. At very high rotation, failure conditions occurred and the ability to shape a CP Grade 2 sheet is decreased; these failures were mainly due to extreme heating, leading to termination of the tests concerned. The main objective of the study is to gain a better understanding of the combined effects that the varied relative motions at the tool/sheet contact zone have on the process conditions.
What is the meaning associated with a single action potential in a neural spike train? The answer depends on the way the question is formulated. One general approach toward formulating this question ...involves estimating the average stimulus waveform preceding spikes in a spike train. Many different algorithms have been used to obtain such estimates, ranging from spike-triggered averaging of stimuli to correlation-based extraction of "stimulus-reconstruction" kernels or spatiotemporal receptive fields. We demonstrate that all of these approaches miscalculate the stimulus feature selectivity of a neuron. Their errors arise from the manner in which the stimulus waveforms are aligned to one another during the calculations. Specifically, the waveform segments are locked to the precise time of spike occurrence, ignoring the intrinsic "jitter" in the stimulus-to-spike latency. We present an algorithm that takes this jitter into account. "Dejittered" estimates of the feature selectivity of a neuron are more accurate (i.e., provide a better estimate of the mean waveform eliciting a spike) and more precise (i.e., have smaller variance around that waveform) than estimates obtained using standard techniques. Moreover, this approach yields an explicit measure of spike-timing precision. We applied this technique to study feature selectivity and spike-timing precision in two types of sensory interneurons in the cricket cercal system. The dejittered estimates of the mean stimulus waveforms preceding spikes were up to three times larger than estimates based on the standard techniques used in previous studies and had power that extended into higher-frequency ranges. Spike timing precision was approximately 5 ms.
Spike sorting the other way Dimitrov, Alexander G.
Neurocomputing (Amsterdam),
06/2003, Letnik:
52
Journal Article
Recenzirano
The problem of identifying neural activity from extracellular recordings is still with us. In recent years there have been a lot of improvements in clustering and identification over the first simple ...techniques. However, the manner in which data samples are selected as putative spike candidates has remained almost unchanged. This part of data processing still remains a largely heuristic procedure. In this work we offer a more quantitative approach to identifying putative spike shapes, which then serve as inputs to clustering methods.
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