Existence and blow up of small-amplitude nonlinear waves with a sign-changing potential

We study the nonlinear wave equation with a sign-changing potential in any space dimension. If the potential is small and rapidly decaying, then the existence of small-amplitude solutions is driven by the nonlinear term. If the potential induces growth in the linearized problem, however, solutions that start out small may blow-up in finite time.Comment: 34 pages, 1 figur

Small-data scattering for nonlinear waves with potential and initial data of critical decay

We study the scattering problem for the nonlinear wave equation with potential. In the absence of the potential, one has sharp existence results for the Cauchy problem with small initial data; those require the data to decay at a rate greater than or equal to a critical decay rate which depends on the order of the nonlinearity. However, scattering results have appeared only for the supercritical case. In this paper, we extend the scattering results to the critical case and we also allow the presence of a short-range potential.Comment: 20 page

A Makefile for Developing Containerized LaTeX Technical Documents

We propose a Makefile for developing containerized $\LaTeX$ technical documents. The Makefile allows the author to execute the code that generates variables, tables and figures (results), which are then used during the $\LaTeX$ compilation, to produce either the draft (fast) or full (slow) version of the document. We also present various utilities that aid in automating the results generation and improve the reproducibility of the document. We release an open source repository of a template that uses the Makefile and demonstrate its use by developing this paper.Comment: 3 pages, 3 figures, 1 tabl

Property Market Purpose Efficiency: An Exploratory Analysis From an Institutional Economics Perspective

Over the last years the issue of property market efficiency has attracted increasing attention in both academic and professional research. Yet, the concept of property market efficiency is poorly developed and inadequately theorised. The conventional approaches (i.e. ‘allocative efficiency’ and ‘efficient market hypothesis’) provide flawed and ambiguous judgements as they assess efficiency with reference to idealised benchmarks, they do not take into account the intrinsic characteristics and dynamic process of the property market and they are artificially dissociated from important operational issues. In turn, institutionalist attempts to articulate more refined and pragmatic conceptualisations of property market efficiency, while they have provided useful insights, remain methodologically underdeveloped and incomplete. Building on the latter approaches the current paper explores a possible way to evaluate the effectiveness of the property market in delivering a combination of outcomes that will generate and/or sustain urban economic development. This provides the basis for the development of the idea of a ‘purpose efficient property market’. To achieve this, two theoretical devices are developed: ‘institutional uncertainty’ and ‘institutionalised variety’. Institutional uncertainty assesses the quality of the wider (urban) institutional arrangements and reflects how effectively the urban socioeconomy adapts to pressures and provides a secure economic environment. Institutionalised variety evaluates particular institutions, in this case the property market, in terms of diversity in institutions, organisations, and products provided. Such a micro-level variety is deemed necessary both for the system to reproduce itself through time and for macro dynamics to be successfully sustained. In that sense, macroeconomic order and relative stability are reinforced alongside, and arise upon, variety and diversity at the micro-level. Putting the arguments together, the property market purpose efficiency is understood with reference to the market’s ability to match ‘institutionalised variety’ to the level of ‘institutional uncertainty’ that the wider urban institutional environment exhibits. In that sense, a purpose efficient property market allocates optimal resources to institutionalised variety, given the level of uncertainty the wider institutional environment carries, and thereby delivers the property products that the economy requires at the prevailing price.

A Framework of Socioeconomic Organisation: Redefining Original Institutional Economics Along Critical Realist Philosophical Lines

The paper develops a theoretical framework of socioeconomic organisation to enrich understanding of the complex interrelation between economy and institutional environment. To achieve this, key elements from both new and old institutional economics are combined and integrated under the philosophical platform of critical realism. Institutionalist research can be, and has been, informed by a range of philosophical positions and analytical standpoints. Critical realism, in turn, has certain advantages, over the other philosophical perspectives, in discussing the institutional organisation of urban socioeconomy. These mainly stem from its ontological arguments that allow the dissociation of institutional structure from human agency, and acknowledge the separate identity and causal powers of institutions without undermining their agent-dependent nature. This is important because it enables a neat identification and analysis of the institutional qualities, mechanisms, causal powers and relations that characterise the socioeconomic fabric. Moreover, the fact that the realist ontology is compatible with a variety of economic theories renders its fusion with institutionalism on the whole both valid and feasible. The paper starts delineating the philosophical tenets of critical realism, which provide the basis for the development of a stratified ontological framework discussing the institutional organisation of the urban socioeconomy. In particular, a three-layer, interlocked reality is identified describing the complexity, multidimensionality, and dynamic character of the socioeconomic world. It is argued that deeper tendencies, capacities, ‘instincts’ and qualities of the human essence (understood as ‘creativity’, ‘emulation’ and ‘culture’) condition the institutional environment (differentiated in economic, political, legal, and social terms), which in turn constitutes the terrain upon which organisational arrangements are manifested and socioeconomic events are actualised. In these terms, institutions are defined as ingrained regularities or established rules of human life that mould and determine agents’ perception, expectations and behaviour, providing order, stability and certainty in social interaction and economic organisation. The paper closes summarising the epistemological and methodological position espoused to establish a generic analytical framework that can be used to investigate the institutional texture of the urban/regional socioeconomic environment.

Deep Learning in Cardiology

The medical field is creating large amount of data that physicians are unable to decipher and use efficiently. Moreover, rule-based expert systems are inefficient in solving complicated medical tasks or for creating insights using big data. Deep learning has emerged as a more accurate and effective technology in a wide range of medical problems such as diagnosis, prediction and intervention. Deep learning is a representation learning method that consists of layers that transform the data non-linearly, thus, revealing hierarchical relationships and structures. In this review we survey deep learning application papers that use structured data, signal and imaging modalities from cardiology. We discuss the advantages and limitations of applying deep learning in cardiology that also apply in medicine in general, while proposing certain directions as the most viable for clinical use.Comment: 27 pages, 2 figures, 10 table

Developmental acquisition of entrainment skills in robot swinging using van der Pol oscillators

In this study we investigated the effects of different morphological configurations on a robot swinging task using van der Pol oscillators. The task was examined using two separate degrees of freedom (DoF), both in the presence and absence of neural entrainment. Neural entrainment stabilises the system, reduces time-to-steady state and relaxes the requirement for a strong coupling with the environment in order to achieve mechanical entrainment. It was found that staged release of the distal DoF does not have any benefits over using both DoF from the onset of the experimentation. On the contrary, it is less efficient, both with respect to the time needed to reach a stable oscillatory regime and the maximum amplitude it can achieve. The same neural architecture is successful in achieving neuromechanical entrainment for a robotic walking task