Hausdorff dimension of random limsup sets

We prove bounds for the almost sure value of the Hausdorff dimension of the limsup set of a sequence of balls in $\mathbf{R}^d$ whose centres are independent, identically distributed random variables. The formulas obtained involve the rate of decrease of the radii of the balls and multifractal properties of the measure according to which the balls are distributed, and generalise formulas that are known to hold for particular classes of measures.Comment: 26 pages, 2 figures; v2: Minor correction

Technology Policy, Gender, and Cyberspace

Event based sampling occurs when the time instants are measured everytime the amplitude passes certain pre-defined levels. This is in contrast with classical signal processing where the amplitude is measured at regular time intervals. The signal processing problem is to separate the signal component from noise in both amplitude and time domains. Event based sampling occurs in a variety of applications. The purpose here is to explain the new types of signal processing problems that occur, and identify the need for processing in both the time and event domains. We focus on rotating axles, where amplitude disturbances are caused by vibrations and time disturbances from measurement equipment. As one application, we examine tire pressure monitoring in cars where suppression of time disturbance is of utmost importance

What is a place? Allowing users to name and define places

From working with location-based information systems we know that positioning is problematic. A different approach was tested, where users themselves were allowed to name and define the places they wanted to use. The question was if they would do so, and if they would understand the notion of “place”. In a user study, 78 users created 84 place labels. The user study also gave us some unexpected input to the users’ perception of place: not only physical, but also virtual places were created

On the Fourier dimension and a modification

We give a sufficient condition for the Fourier dimension of a countable union of sets to equal the supremum of the Fourier dimensions of the sets in the union, and show by example that the Fourier dimension is not countably stable in general. A natural approach to finite stability of the Fourier dimension for sets would be to try to prove that the Fourier dimension for measures is finitely stable, but we give an example showing that it is not in general. We also describe some situations where the Fourier dimension for measures is stable or is stable for all but one value of some parameter. Finally we propose a way of modifying the definition of the Fourier dimension so that it becomes countably stable, and show that a measure has modified Fourier dimension greater than or equal to $s$ if and only if it annihilates all sets with modified Fourier dimension less than $s$.Comment: v2: Added some remarks in the introduction and after Example 6. v3: Revised the introduction, strengthened Lemma 6, added Proposition 5 and Example 8. To appear in Journal of Fractal Geometr

Consumers perception of genetically modified horticultural food

Genetically modified food within the horticulture sector is strictly regulated in the European Union today. In a future where the question of whether to adopt biotechnology, regarding genetically modified or gene-edited horticultural products, the perception of such technology is of importance. This study aimed to investigate the perception regarding genetically modified food and the underlying thoughts that drives these statements. Also, the perception of related technology, the gene-editing technology CRISPR/Cas was investigated. This gene-editing technology is one of the most promising technologies and with precision alter DNA in crops today, and therefore, perception towards this technology is highly relevant to investigate. This study was based on interviews including 8 participants that were interviewed for 1 hour, regarding the perception of genetically modified- and gene editing technologies. The participants were interviewed with a semi-structured approach which allowed discussions to take place. The material was then analyzed, discussed, and compared with results and conclusions of available literature regarding this topic, to strengthen the findings in this study. A special focus was to see if there were any links between statements and positions regarding gender, age, and knowledge level. The results showed that there was no clear link regarding education level and position towards the concept of GM food. However, there was a connection between both gender and age and the position and attitude towards GM food. Furthermore, gene-editing technology seemed to be more accepted than traditionally gene-modified technologies. There was also an observed knowledge need amongst the participants. The clearest connection towards a positive perception towards GM food seems the perceived knowledge regarding the understanding of the technology and was concluded in this study. An expression such as, unnatural and health hazards were mostly observed of those who rejected GM food. This study contains a relatively few numbers of participants, which means that the results don’t reflect the perception of the public, which in turn points to the importance of more research in the area

Scaling up MIMO: Opportunities and Challenges with Very Large Arrays

This paper surveys recent advances in the area of very large MIMO systems. With very large MIMO, we think of systems that use antenna arrays with an order of magnitude more elements than in systems being built today, say a hundred antennas or more. Very large MIMO entails an unprecedented number of antennas simultaneously serving a much smaller number of terminals. The disparity in number emerges as a desirable operating condition and a practical one as well. The number of terminals that can be simultaneously served is limited, not by the number of antennas, but rather by our inability to acquire channel-state information for an unlimited number of terminals. Larger numbers of terminals can always be accommodated by combining very large MIMO technology with conventional time- and frequency-division multiplexing via OFDM. Very large MIMO arrays is a new research field both in communication theory, propagation, and electronics and represents a paradigm shift in the way of thinking both with regards to theory, systems and implementation. The ultimate vision of very large MIMO systems is that the antenna array would consist of small active antenna units, plugged into an (optical) fieldbus.Comment: Accepted for publication in the IEEE Signal Processing Magazine, October 201

GeoNotes: A Location-based Information System for Public Spaces

The basic idea behind location-based information systems is to connect information pieces to positions in outdoor or indoor space. Through position technologies such as Global Positioning System (GPS), GSM positioning, Wireless LAN positioning o