Multiplexing oscillatory biochemical signals

In recent years it is increasingly being recognized that biochemical signals are not necessarily constant in time and that the temporal dynamics of a signal can be the information carrier. Moreover, it is now well established that components are often shared between signaling pathways. Here we show by mathematical modeling that living cells can multiplex a constant and an oscillatory signal: they can transmit these two signals through the same signaling pathway simultaneously, and yet respond to them specifically and reliably. We find that information transmission is reduced not only by noise arising from the intrinsic stochasticity of biochemical reactions, but also by crosstalk between the different channels. Yet, under biologically relevant conditions more than 2 bits of information can be transmitted per channel, even when the two signals are transmitted simultaneously. These observations suggest that oscillatory signals are ideal for multiplexing signals.Comment: Includes S

The effect of feedback on the fidelity of information transmission of time-varying signals

Living cells are continually exposed to environmental signals that vary in time. These signals are detected and processed by biochemical networks, which are often highly stochastic. To understand how cells cope with a fluctuating environment, we therefore have to understand how reliably biochemical networks can transmit time-varying signals. To this end, we must understand both the noise characteristics and the amplification properties of networks. In this manuscript, we use information theory to study how reliably signalling cascades employing autoregulation and feedback can transmit time-varying signals. We calculate the frequency-dependence of the gain-to-noise ratio, which reflects how reliably a network transmits signals at different frequencies. We find that the gain-to-noise ratio may differ qualitatively from the power spectrum of the output, showing that the latter does not directly reflect signaling performance. Moreover, we find that auto-activation and auto-repression increase and decrease the gain-to-noise ratio for all of frequencies, respectively. Positive feedback specifically enhances information transmission at low frequencies, while negative feedback increases signal fidelity at high frequencies. Our analysis not only elucidates the role of autoregulation and feedback in naturally-occurring biological networks, but also reveals design principles that can be used for the reliable transmission of time-varying signals in synthetic gene circuits.Comment: Article 17 pages, S1: 12 page

Multiplexing Biochemical Signals

In this paper we show that living cells can multiplex biochemical signals, i.e. transmit multiple signals through the same signaling pathway simultaneously, and yet respond to them very specifically. We demonstrate how two binary input signals can be encoded in the concentration of a common signaling protein, which is then decoded such that each of the two output signals provides reliable information about one corresponding input. Under biologically relevant conditions the network can reach the maximum amount of information that can be transmitted, which is 2 bits.Comment: 4 pages, 4 figure

The effects of brand image on online perceived quality, online brand personality and purchase intention

The purpose of this study is to determine the influence of brand image, online perception of credibility and online perception of buying interest in the market of smartphone products with a case study in the Semarang City, Indonesia. It is a quantitative research by using a survey with 200 questionnaires. The results are valid and reliable against the interest in buying smartphone products. Furthermore, the brand image is positively related but not significant to the interest of buying smartphone products. Online brand personality and online perceived quality are positively and significantly related to the interest of buying.peer-reviewe

The Willingness of Dutch Citizens to Participate in a Prosumer Community: A Stated Choice Experiment

The demand for energy in the world is continually rising. The local prosumer communities can be well-placed to identify local energy needs, establish and support initiatives to reduce the energy demand. This paper aims to understand people’s willingness to participate in a prosumer community and the influential factors based on socio-demographic characteristics and attitudes. For that purpose, a stated choice experiment is designed to measure the preferences of Dutch citizens to participate in a prosumer community. In this research, two alternatives are presented to the respondents: own initiative and outsourcing of energy efficient implementations. In addition to the stated choice experiment, environmental statements were given to the respondents to assess their environmental attitudes. As a result of the data collection, 184 respondenses are obtained. A latent class model is used to analyse the data and rho-square is found to be 0.264. According to the results, two groups can be identified respectively as enthousiasts and conservatives with regard to willingness to participate in a prosumer community. In terms of socio-demographics and attitudes, there are statistically significant differences between the groups. These results are found to be useful to promote bottom-up initiatives and to suggest policies in order to form prosumer communities in local territories

Darling v. Charleston Community Memorial Hospital and Its Legacy

An in-depth discussion of the historic decision in a landmark case regarding the evolution of hospital liability