A complex network approach to urban growth

The economic geography can be viewed as a large and growing network of interacting activities. This fundamental network structure and the large size of such systems makes complex networks an attractive model for its analysis. In this paper we propose the use of complex networks for geographical modeling and demonstrate how such an application can be combined with a cellular model to produce output that is consistent with large scale regularities such as power laws and fractality. Complex networks can provide a stringent framework for growth dynamic modeling where concepts from e.g. spatial interaction models and multiplicative growth models can be combined with the flexible representation of land and behavior found in cellular automata and agent-based models. In addition, there exists a large body of theory for the analysis of complex networks that have direct applications for urban geographic problems. The intended use of such models is twofold: i) to address the problem of how the empirically observed hierarchical structure of settlements can be explained as a stationary property of a stochastic evolutionary process rather than as equilibrium points in a dynamics, and, ii) to improve the prediction quality of applied urban modeling.evolutionary economics, complex networks, urban growth

Finding radio transients

Modern radio telescopes are data-intensive machines, producing many TB of data every night. Amongst this deluge of data are transient and variable phenomena, whose study can shed new light on processes as varied as stellar dynamos and the accretion discs in supermassive black holes. In this work I demonstrate the applicability of different methods to the discovery of these astrophysical transients and variables coming from telescopes such as MeerKAT. I first consider a standard approach to discovering transients by characterising their variability. By making use of even modest sampling with the high sensitivity and wide field of view of MeerKAT, I demonstrate how we are now able to uncover new transients almost by accident - if we exclude the vast amount of time spent planning, building and operating excellent telescopes, efficient pipelines and well- crafted observing proposals. In this work I found a stellar flare from a nearby M dwarf, which was then followed up and complemented by optical and X-ray photometry and spectroscopy, providing new insights on the system. Next I built a citizen science platform in order to perform such transient searches at scale, making use of a wide range of data available in the MeerKAT archive. I detail the process of review and beta-testing that resulted in the final design of the Bursts from Space: MeerKAT project. Over 1000 volunteers took part, demonstrating a healthy appetite for further Zooniverse data releases. Volunteers discovered or recovered a wide range of phenomena, from flare stars and pulsars to scintillating AGN and transient OH maser emission. I was also able to use the known transients in our fields to understand some reasons why interesting sources may be missed and will fold this learning through to future iterations of the project. This is the first demonstration of volunteers finding radio transients in images. Finally, I show how anomaly detection, an unsupervised machine learning approach, is a suitable tool for finding these variable phenomena at scale, as is required for modern astronomical surveys. I use three feature sets as applied to two anomaly detection techniques in the Astronomaly package and analyse anomaly detection performance by comparison with citizen science labels. By using transients found by citizen scientists as a ground truth I demonstrate that anomaly detection techniques can recall over half of the radio transients within 10% of the sample dataset. I find that the choice of feature set is crucial, especially when considering available resources for human inspection and follow-up. I find that active learning on ∼2% of the data improves recall by up to 10%, depending on the feature-model pair. The best performing feature-model pairs result in a factor of 5 times fewer sources requiring vetting by humans. This is the first effort to apply anomaly detection techniques to finding radio transients and shows great promise for application to other datasets, a real-time transient detection system and upcoming large surveys

Mass and Transverse Mass Effects on the Hadron Emitter Size

We investigate the dependence of the longitudinal emitter dimension of identical bosons, produced in the hadronic Z$^0$ decays, on their transverse mass obtained from 2-dimensional Bose-Einstein correlations (BEC) analyses. We show that this dependence is well described by the expression $r_{||}=c\sqrt{\hbar\Delta t}/\sqrt{m_T}$, deduced from the uncertainty relations, setting $\Delta t$ to be a constant of the order of $10^{-24}$ sec. This equation is essentially identical to the one previously applied to the 1-dimensional BEC results for the emitter radius dependence on the boson mass itself. It is further shown that a very similar behaviour exists also for the dependence of the interatomic separation in Bose condensates on their atomic masses when they are at the same very low temperature.Comment: 10 pges, 2 figure

String Effects on Fermi--Dirac Correlation Measurements

We investigate some recent measurements of Fermi--Dirac correlations by the LEP collaborations indicating surprisingly small source radii for the production of baryons in $e^+e^-$-annihilation at the $Z^0$ peak. In the hadronization models there are besides the Fermi--Dirac correlation effect also a strong dynamical (anti-)correlation. We demonstrate that the extraction of the pure FD effect is highly dependent on a realistic Monte Carlo event generator, both for separation of those dynamical correlations which are not related to Fermi--Dirac statistics, and for corrections of the data and background subtractions. Although the model can be tuned to well reproduce single particle distributions, there are large model-uncertainties when it comes to correlations between identical baryons. We therefore, unfortunately, have to conclude that it is at present not possible to make any firm conclusion about the source radii relevant for baryon production at LEP

Identification and transfer of important factors for sustainability initiatives implementation

ABSTRACT Cardo is a large, multinational previously fragmented company with a history of completely separated management and decision processes (between the divisions), this has enabled as many different ways of choosing and implementing different initiatives as there are offices. The latest step in the change process was implemented during the spring of 2010, since then, Cardo consists of two divisions with the purpose of further unifying the divisions under the Cardo brand. The two new divisions are Cardo entrance solutions and Cardo flow solutions. Cardo mainly operates in the water and logistics area, two areas that because of the recent changes in the environmental focus among most companies have become of the highest importance for a future sustainable company as well as society. This fact shows that there is a huge business potential for the organization that manages to integrate the environmental work into their operations. Within the organization several sustainability initiatives have been implemented and Cardo wants to identify these initiatives in order to learn and evolve from them which hopefully will result in that Cardo will stand better prepared for all the upcoming sustainability initiatives. The purpose of this report is therefore to investigate previously implemented sustainability initiatives, mainly ones with an environmental and economical focus in order to identify the most important factors for the implementation of sustainability initiatives. The three investigated initiatives will all be analyzed separately from a series of theoretical areas. In the final chapter they are compared to each other in order to identify what was done in a good way and what needs to be improved. Based on the theory and the empirical findings from the investigated initiatives the most important areas in which a discussion is shown are kind of change, statement of direction, involvement, communication, motivation and leadership. These findings are all closely connected and affect each other to a great extent. Therefore it is important in to follow them from the very beginning of each new initiative. Keywords Change management, strategy, communication, knowledge transfer, situational leadership, motivation, sustainabilit

Prospects of Bitcoin - An evalutation of its future

The main goal of this thesis is to investigate the properties and prospects of the new digital currency, Bitcoin. How is it structured and is there a possibility of it having a substantial impact on the financial sector or today’s monetary systems? Through macroeconomic theory, financial models and academic writing we will explain the fundamentals of money, how the Bitcoin network functions and in what ways it could be used in the future. The problems lie in the many uncertainties that follow a completely decentralized currency including price instability, lack of regulation and self-policing. Will it become an established, stable currency? We believe not, but it could very well grow into being a useful complement to today’s current financial sector and drive institutions towards becoming more efficient. As this is a completely new phenomenon, many questions remain unanswered. However, what is in store for Bitcoin, only time can tell

The community work programme : potentials and problems

Abstract: This article provides a detailed and critically reflective ‘insider’ account of the origins and development of a Community Work Programme as a public employment programme intervention. The article explores the significant potential of such a Community Work Programme to reduce unemployment and improve socio-economic livelihoods for programme participants, and its potential to model public/private alignment across sectors that complements what can be accomplished within the budgetary constraints of the central government alone. It also describes the challenges of programme implementation as a social policy intervention, arising in part from the difficulties of scaling up successful pilots to create a nationwide programme. The article demonstrates real achievements but also the difficulties of engagement with the state by non-profit organisations, and the difficulties of forging sustainable partnerships between communities and government around shared

Increase of Effective String Tension and Production of Strange Particles

The increase of effective string tension as a result of the hard gluon kinks on a string is investigated using a parametrization form. In this form the effective string tension increasing with energies in hadron-hadron collisions is due to the mini-jet (gluon) production in the collisions. The data of the energy dependence of the strange quark suppression factor in hh collisions are very well reproduced with this mechanism. Meanwhile, the experimental phenomena of approximate energy independence of the strange quark suppression factor in e$^+$e$^-$-annihilations are discussed.Comment: LaTeX, 2 figure