Probing the basins of attraction of a recurrent neural network

A recurrent neural network is considered that can retrieve a collection of patterns, as well as slightly perturbed versions of this `pure' set of patterns via fixed points of its dynamics. By replacing the set of dynamical constraints, i.e., the fixed point equations, by an extended collection of fixed-point-like equations, analytical expressions are found for the weights w_ij(b) of the net, which depend on a certain parameter b. This so-called basin parameter b is such that for b=0 there are, a priori, no perturbed patterns to be recognized by the net. It is shown by a numerical study, via probing sets, that a net constructed to recognize perturbed patterns, i.e., with values of the connections w_ij(b) with b unequal zero, possesses larger basins of attraction than a net made with the help of a pure set of patterns, i.e., with connections w_ij(b=0). The mathematical results obtained can, in principle, be realized by an actual, biological neural net.Comment: 17 pages, LaTeX, 2 figure

Pioneering Sand Motor: The Sand Motor as source to rethink anthropogenic coastal modifications in cultural public space

Now that people all around the world are slowly starting to rethink how humanity and the planet are interrelated, new questions have arisen around the understanding of time and the perception of place. It’s not merely a technical or a political challenge that we are facing, it is also a cultural one. The Sand Motor - as the first of its kind - uses the forces of the wind and waves as active agengies of change, but can it be valued as a driving force for humanity to change as well? Drawing from primary artistic research of the sea, coastal transitions, climate change and human appropriations in The Netherlands and abroad, we can state that the ephemeral nature of the Sand Motor itself challenges a polyphonic discourse for co-creation of experiential knowledge. The Sand Motor can be perceived as a man-made intervention in public space, an open-air, publicly accessible research site. Over the past 10 years, Satellietgroep redefined the Sand Motor as a cultural phenomenon, connecting the Sand Motor to the realms of art, culture, and heritage. This essay discusses a series of human-inclusive art projects, in which the Sand Motor evolves from a non-place into a vital learning environment for the cross-pollination of ideas and experimentations to rethink culture and nature. They demonstrate that pioneering with the Sand Motor should include pioneering with the social and cultural values of this artifact, not only to raise public and professional climate-consciousness, but also to adopt it as a human-inclusive landscape. This may well be the most underestimated value of the Sand Motor itself, and of the concept of Building with Nature in general

Newfound Religion: Term 17(3) of the Newfoundland Act and its Challenge to the Current Discourse on Freedom of Religion in the Public Sphere

Underlying the dominant legal and theoretical approaches to the freedom of religion in the public sphere is a discourse which assumes that religion is a contestable or mutable aspect of public life. As a result of this assumption, our current approach holds that the role of religion may be altered according to the perceived benefits and burdens of its presence. The resulting consensus predominately prefers the absence of religion in the public space where government regulation exists. By amending its constitutional terms of union with Canada to permit religious observances in their public school system, Newfoundland and Labrador has protected activities which, short of their constitutional protections, would certainly be condemned by our current approach. However, denouncing this provision fails to account for the current and historical relationship which religion has had in the education of the citizens of Newfoundland and Labrador. The following discussion examines this discord, a discord which profoundly challenges whether our current approach is based on a faulty premise. It will be submitted that in appropriate circumstance the existence of religion in the public sphere should not be challenged, but rather acknowledged and accepted. In such cases this acknowledgment of religion may need to form the foundation or starting point for our approach to religion

A recurrent neural network with ever changing synapses

A recurrent neural network with noisy input is studied analytically, on the basis of a Discrete Time Master Equation. The latter is derived from a biologically realizable learning rule for the weights of the connections. In a numerical study it is found that the fixed points of the dynamics of the net are time dependent, implying that the representation in the brain of a fixed piece of information (e.g., a word to be recognized) is not fixed in time.Comment: 17 pages, LaTeX, 4 figure

Evolution of Turbidity Currents: New insights from direct field measurements

Underwater sediment density flows, including turbidity currents, are capable of transporting vast amounts of sediment, nutrients and pollutants to the deep-sea. These flows can be powerful, causing damage to seafloor infrastructure. Understanding how the flow velocity and magnitude develops over distance is thus important for risk assessments, as well as determining sediment fluxes. However, as few direct measurements are available, these flows remain rather poorly understood. This thesis aims to use three direct monitoring datasets from three different oceanographic settings worldwide that have captured turbidity currents in unusual detail, allowing for unique analysis of their flow evolution. Detailed measurements of turbidity currents in Monterey Canyon, offshore California, show that their evolution depends on the initial velocity and the availability of an easily erodible substrate. Turbidity currents exceeding a velocity threshold can plateau with near-uniform velocities, and thus run out over greater distances. A new model is proposed for how these near-uniform velocities are obtained. In the Var Canyon-River system, France, nearshore measurements are used to analyse turbidity current velocity structures, and how these develop over distance. Turbidity currents are shown to self-organise over short distances by amalgamation of velocity peaks, which is partly controlled by erodible substrate availability. This efficient self-organisation occurs within 10 km, after which the original trigger is indiscernible. This has important implications for interpreting turbidity current deposits. Bute Inlet, British Columbia, is one of the most complete studies, where source-to-sink direct measurements are combined with sediment cores. These data allow for a unique analysis of turbidity current activity over space and time. The current-day channelized system is highly active with yearly events, although these events are low magnitude. In contrast, distally the system shows high magnitude events occurring on centennial time scales. These data suggest that infrequent mechanisms control large-scale events currently not observed directly. This thesis provides a detailed analysis of turbidity current development over distance, essential for determination of sediment fluxes and hazard assessment

From lowering plasma lipids to fight atherosclerosis to studies into the biogenesis of apoB-containing lipoproteins and their relationship with hepatic steatosis

To improve our understanding of lipid homeostasis, this thesis has focused on increasing our understanding of the production and secretion of apolipoprotein (apo)B containing lipoproteins in the liver (very low-density lipoprotein; VLDL) and the small intestine (chylomicrons). This has led to the discovery and validation of small leucine-rich protein 1 (SMLR1) as a novel player in lipid metabolism: hepatic ablation of SMLR1 in mice results in major reductions in both plasma cholesterol and triglyceride levels and protects against atherosclerosis but also induces non-alcoholic fatty liver disease. Notably, this phenotype was not associated with insulin resistance. Further molecular studies show that proteins with roles in lipid droplet biology are physically associated with SMLR1 while ultrastructural studies reveal a close association between lipid droplets and VLDL biology that warrants further investigation. We also identified a second candidate gene (ERICH4) encoding for glutamate-rich protein 4 which was predicted to play a role in the production of chylomicrons. Supported by prediction software and human genetic studies, we generated a whole-body ERICH4 knockout mouse model which unfortunately does not show a lipid phenotype. The current data do support however further studies into the role of ERICH4 in humans. In addition, we critically examined the existing literature on the molecular aspects of VLDL assembly, trafficking and secretion machinery and highlighted current knowledge gaps. In conclusion, the work described in this thesis contributes to fundamental VLDL research potentially aiding the development of drugs targeting liver steatosis and atherosclerosis in cardiometabolic patients

Biologically inspired learning in a layered neural net

A feed-forward neural net with adaptable synaptic weights and fixed, zero or non-zero threshold potentials is studied, in the presence of a global feedback signal that can only have two values, depending on whether the output of the network in reaction to its input is right or wrong. It is found, on the basis of four biologically motivated assumptions, that only two forms of learning are possible, Hebbian and Anti-Hebbian learning. Hebbian learning should take place when the output is right, while there should be Anti-Hebbian learning when the output is wrong. For the Anti-Hebbian part of the learning rule a particular choice is made, which guarantees an adequate average neuronal activity without the need of introducing, by hand, control mechanisms like extremal dynamics. A network with realistic, i.e., non-zero threshold potentials is shown to perform its task of realizing the desired input-output relations best if it is sufficiently diluted, i.e. if only a relatively low fraction of all possible synaptic connections is realized

The collapse of WTC 7: A re-examination of the “simple analysis” approach

Although the events of that tragic day happened 14 years ago, there remain nagging questions of why the 47 storey WTC 7 steel framed structure collapsed, when it was NOT hit by an airplane.  We will review the official rationale of how the collapse events started, and why, in our opinion, the explanation is judged to be wrong.  Then, we will proceed with another scenario that says “Okay – let’s assume that the two critical storeys did sustain extremely hot fires, so much so that 2/3rds of their columns totally lost axial resistance capability”.  We then proceed to employ Newton’s laws to inquire whether there was sufficient gravitational potential energy due to live and dead loadings in upper and lower floors to overcome the resistance offered by the remaining columns, together with floor slabs known to have been pulverized to reduced particle sizes by surface to surface crushing.  Our conclusion suggests that Newton’s laws of motion and energy conservation considerations would have had to have been violated to explain that building’s total collapse within a debris pile several storeys high.Supplementary Sources: Clip from "9-11 in the Academic Community

Performance-based fire protection of office buildings: A case study based on the collapse of WTC 7

This article points out the benefits of employing a performance based analysis approach for ascertaining the likelihood that travelling fires in an office building could induce a localized failure that might trigger its collapse. The case study chosen is Building 7 of the World Trade Center complex. Based on the parametric study undertaken, our findings were that the fire-protected steel floor beam, identified as the initiator of the cascade of events that followed, could not have done so, virtually under any circumstance.Supplementary Sources: Clip from "9-11 in the Academic Community