Search results for "ion channel"
showing 10 items of 567 documents
An empirical analysis of online price dispersion in the Italian airline industry
2015
Firms operating in the electronic marketplace set and adjust prices to affect demand and profitability. In service markets, such as airline markets, different prices are commonly offered by diverse firms to accommodate to a variety of market segments having particular sets of consumer attitudes. This variation in prices is the price dispersion and is based on market distinctiveness deriving from customer heterogeneity as well as the peculiar competition in the specific market arena. In this paper we use a panel dataset from the Italian airline market to investigate the role of competition and different online channels in the emergence of price dispersion. Specifically, we examine the unclea…
Markov Chain Analysis of CA and CF with Multiple Types of Users
2019
In the previous chapter, we studied in depth the impact of CA and CF on traffic flows in systems where there exists only one type of users with one type of flows. In this chapter, the influence of CA and CF is studied in a more complicated scenario, i.e., the one in which multiple users exist, and where users have different priorities in using channel resources. CRN is a typical example for such a system, and we study the CRNs where PUs and SUs have one type of flows for each.
A Single radio based channel datarate-aware parallel rendezvous MAC protocol for cognitive radio networks
2009
Channel hopping based parallel rendezvous multichannel MAC protocols have several advantages since they do not need a control channel, require only one transceiver, and produce higher system capacity. However, channel hopping sequences in existing parallel rendezvous MAC protocols have been designed as irrelevant to channel datarates, leading to under-utilization of channel resources in multi-rate multi-channel networks. Considering that datarates among channels may be different, we propose a dynamic parallel rendezvous multichannel MAC protocol for synchronized cognitive radio networks in which the secondary users adjust their own distinct hopping sequences according to the datarates of th…
Estimation of the Velocity of Multiple Moving Persons in Non-Stationary Indoor Environments from Received RF Signals
2019
This paper presents a new accurate iterative procedure to estimate the time-variant (TV) velocity, i.e., TV speed, TV vertical angle-of- motion (VAOM), and TV horizontal angle-of-motion (HAOM), of multiple moving objects/persons in three-dimensional (3D) non-stationary indoor propagation environments. The indoor space is assumed to be equipped with a distributed 3x3 multiple-input multiple-output (MIMO) system. The proposed procedure focuses on estimating the TV speed, TV VAOM, and TV HAOM by matching the spectrogram of the complex channel gain of a non- stationary indoor channel model to the spectrogram obtained from received radio frequency (RF) signals. Together with the velocity …
A New Iterative Estimation Procedure for the Localization of Passive Stationary Objects from Received RF Signals in Indoor Environments
2019
This paper deals with the localization of passive stationary objects from the received radio- frequency (RF) signals in 3-dimensional (3D) indoor environments. Each object located in the 3D indoor environment is modelled by a single point scatterer. The propagation space is equipped with a multiple-input multiple-output (MIMO) wireless communication system. The employed channel model is flexible and allows to have a line-of-sight (LOS) component as well as single- and double- bounce scattering components. Here, we present a new accurate iterative estimation technique for computing the optimal coordinates as well as the number of the main stationary objects (scatterers) in indoor areas. The …
Friction Factor for Gravel-Bed Channel with High Boulder Concentration
2000
This paper reports the results of an experimental investigation on flow resistance law for a gravel-bed channel having bed arrangements characterized by different values of the number of boulders. The dependence is studied of a parameter, proposed for describing the gravel-bed surfaces, on the boulder concentration and on the ratio between the median diameter of the coarser particles and the median diameter of the bed layer. Flume measurements carried out for the hydraulic condition of \Itransition\N and \Ilarge-scale\N roughness (1.5 ≤ \ih/\id\d5\d0 ≤ 6.9) show that the intercept of the semilogarithmic flow resistance law depends on the ratio and on boulder concentration. For concentration…
The influence of roughness geometry and shields parameter on flow resistance in gravel-bed channels
1997
The spatial variability of bed particles of a gravel-bed channel is analysed and treated experimentally in order to simulate the effects of the arrangement of coarse bed elements on the flow resistance law. For the studied bed patterns, characterized by the concentration Γ of coarser elements arranged on the bed layer, a particle arrangement parameter α is proposed. The α parameter is useful for estimating the intercept b0 of the semi-logarithmic flow resistance law deduced by flume measurements carried out for the hydraulic condition of large-scale and transition roughness. The differences between the experimental friction factor parameter values and the ones calculated by the proposed sem…
Ion conduction in the KcsA potassium channel analyzed with a minimal kinetic model.
2004
We use a model by Nelson to study the current-voltage and conductance-concentration curves of bacterial potassium channel KcsA without assuming rapid ion translocation. Ion association to the channel filter is rate controlling at low concentrations, but dissociation and transport in the filter can limit conduction at high concentration for ions other than ${\mathrm{K}}^{+}$. The absolute values of the effective rate constants are tentative but the relative changes in these constants needed to qualitatively explain the experiments should be of significance.
Photochemical and Chemical Two-Channel Control of Functional Nanogated Hybrid Architectures
2007
Anisotropic flow in striped superhydrophobic channels
2012
We report results of dissipative particle dynamics simulations and develop a semi-analytical theory of an anisotropic flow in a parallel-plate channel with two superhydrophobic striped walls. Our approach is valid for any local slip at the gas sectors and an arbitrary distance between the plates, ranging from a thick to a thin channel. It allows us to optimize area fractions, slip lengths, channel thickness and texture orientation to maximize a transverse flow. Our results may be useful for extracting effective slip tensors from global measurements, such as the permeability of a channel, in experiments or simulations, and may also find applications in passive microfluidic mixing.