All-sky Radio SETI

Over the last decade, Aperture Arrays (AA) have successfully replaced parabolic dishes as the technology of choice at low radio frequencies - good examples are the MWA, LWA and LOFAR. Aperture Array based telescopes present several advantages, including sensitivity to the sky over a very wide field-of-view. As digital and data processing systems continue to advance, an all-sky capability is set to emerge, even at GHz frequencies. We argue that assuming SETI events are both rare and transitory in nature, an instrument with a large field-of-view, operating around the so-called water-hole (1-2 GHz), might offer several advantages over contemporary searches. Sir Arthur C. Clarke was the first to recognise the potential importance of an all-sky radio SETI capability, as presented in his book, Imperial Earth. As part of the global SKA (Square Kilometre Array) project, a Mid-Frequency Aperture Array (MFAA) prototype known as MANTIS (Mid- Frequency Aperture Array Transient and Intensity-Mapping System) is now being considered as a precursor for SKA-2. MANTIS can be seen as a first step towards an all-sky radio SETI capability at GHz frequencies. This development has the potential to transform the field of SETI research, in addition to several other scientific programmes.Comment: 7 pages, 4 figures, accepted for publication, Proceedings of Science, workshop on "MeerKAT Science: On the Pathway to the SKA", held in Stellenbosch 25-27 May 2016. Comments welcom

The latest on Apertif

We describe a Phased Array Feed (PAF) system, called Apertif, which will be installed in the Westerbork Synthesis Radio Telescope (WSRT). The aim of Apertif is, at frequencies from 1.0 to 1.7 GHz, to increase the instantaneous field of view of the WSRT 8 deg^2 and its observing bandwidth to 300 MHz with high spectral resolution. This system will turn the WSRT into an effective survey telescope with scientific applications ranging from deep surveys of the northern sky of HI and OH emission and polarised continuum to efficient searches for pulsars and transients. We present results obtained with a prototype PAF installed in one of the WSRT dishes. These results demonstrate that at decimetre wavelengths PAFs have excellent performance and that even for a single beam on the sky they outperform single feed radio dishes. PAFs turn radio telescopes into very effective survey instruments. Apertif is now fully funded and the community is invited to express their interest in using Apertif (http://www.astron.nl/radio-observatory/call-expressions-interest-apertif-surveys )Comment: Talk presented at 'A New Golden Age for Radio Astronomy', International SKA Forum 2010, 10-14 June 2010, Hof van Saksen, N

Topographic hub maps of the human structural neocortical network

Hubs within the neocortical structural network determined by graph theoretical analysis play a crucial role in brain function. We mapped neocortical hubs topographically, using a sample population of 63 young adults. Subjects were imaged with high resolution structural and diffusion weighted magnetic resonance imaging techniques. Multiple network configurations were then constructed per subject, using random parcellations to define the nodes and using fibre tractography to determine the connectivity between the nodes. The networks were analysed with graph theoretical measures. Our results give reference maps of hub distribution measured with betweenness centrality and node degree. The loci of the hubs correspond with key areas from known overlapping cognitive networks. Several hubs were asymmetrically organized across hemispheres. Furthermore, females have hubs with higher betweenness centrality and males have hubs with higher node degree. Female networks have higher small-world indices

Gibbs Energy Dynamic Yield Method (GEDYM): Predicting microbial growth yields under energy-limiting conditions

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.gca.2018.08.023 © 2018. This open-access version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/Biomass-explicit biogeochemical models assign microbial growth yields (Y) using values measured in the laboratory or predicted using thermodynamics-based methods. However, Y values are rarely measured under the low energy delivery conditions that often prevail in the subsurface, and existing predictive methods for calculating Y values when the catabolic energy supply rate is limited remain poorly tested. Here, we derive and validate a new semi-theoretical method for calculating Y values: the Gibbs Energy Dynamic Yield Method (GEDYM). Method validation relies on a compilation of 132 geochemically relevant literature Y values comprising predominantly (60%) low energy (> −25 kJ (mol e−)−1) metabolisms. GEDYM is based on estimating the Gibbs energy change of the metabolic reaction (ΔGmet), which links the Gibbs energy changes of the catabolic (ΔGcat) and anabolic (ΔGan) reactions of a microorganism through its growth yield. Given that the values of ΔGmet,ΔGcat and ΔGan all depend on their respective reaction quotients, the resulting Y values account for changes in the chemical environment surrounding the cells. GEDYM incorporates an empirical relationship that accurately estimates the extent to which ΔGmet deviates from its standard state value from the relative difference between ΔGcat and its corresponding standard state value. GEDYM yields Y values with lower relative errors and statistical bias than the existing Gibbs energy dissipation method (GEDM). Using dissimilatory iron reduction, sulfate reduction and methanogenesis as examples, we illustrate the importance of considering variations in ΔGcat and ΔGan when predicting Y values for individual metabolisms. Because of its ability to dynamically adjust the values of ΔGmet and Y to variable geochemical conditions, GEDYM yields a more realistic representation of geomicrobial activity in predictive reactive transport models.Canada Excellence Research Chairs, Government of CanadaU.S. Department of Energy ["DE-SC0005520"

On the Sparsity and Aperiodicity of a Base Station Antenna Array in a Downlink MU-MIMO Scenario

An application study into irregular sparse arrays (ISAs) is proposed to function as base station antennas (BSAs) in a mm-wave multi-user multiple-input multiple-output (MU-MIMO) system. The results show that the sum rate capacity of ISAs can be increased relative to regularly-spaced BSA arrays with half a wavelength element separation, especially for a high number of users. This is due to the narrower beams formed by the larger antenna apertures of sparse arrays. Furthermore, the aperiodic distribution of antenna elements alleviates the problem of grating lobes in sparse arrays and is seen to improve the average power consumption of power amplifiers at the same time

Політичні стереотипи та стереотипізація мислення: роль та значення у системі іміджевих комунікацій

Всебічно розглянуто особливості стереотипізації мислення як важливого чинника у процесі сприйняття та аналізу особою або групою осіб суспільно-політичної дійсності. Досліджено природу, джерела та механізми формування політичних стереотипів та показано їх роль і значення у системі іміджевих комунікацій. Наголошено на необхід- ності аналізу існуючої системи стереотипів при створенні іміджу суб’єкта політики.There have been thoroughly examined peculiarities of stereotyping of thinking as an important factor in the process of perception and analysis of socio-political reality by a person or a group of people. There have been investigated the nature, sources and mechanism of political stereotypes formation and showed their role and meaning in the system if image communications. There has been put an emphasis on the necessity of analysis of the existing system of stereotypes while creating the image of a subject of policy

Validation of NODDI estimation of dispersion anisotropy in V1 of the human neocortex

This work validates the estimation of neurite dispersion anisotropy in the brain, using Bingham-NODDI [1], an extension of the diffusion MRI technique called NODDI [2]. The original NODDI provides indices of neurite (axons and dendrites) morphology that are sensitive and specific to microstructural changes [3-7]. Bingham-NODDI additionally allows the estimation of neurite dispersion anisotropy, which can enhance the accuracy of tractography algorithms [8]. The in vivo feasibility of Bingham-NODDI has been evaluated in [1]. The present study validates its indices using high-resolution ex vivo imaging data of the human primary visual cortex (V1), a well characterised region of the neocortex known to include fibres that fan or bend into the cortical layers