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Ben de Lacy Costello

Publications and source records attributed to Ben de Lacy Costello.

At least 19 recordsLinked to original sources
arXiv2015

Practical circuits with Physarum Wires

Purpose: Protoplasmic tubes of Physarum polycephalum, also know as Physarum Wires (PW), have been previously suggested as novel bio- electronic components. Until recently, practical examples of electronic circuits using PWs have been limited. These PWs have been shown to be self repairing, offering significant advantage over traditional electronic components. This article documents work performed to produce practical circuits using PWs. Method: We have demonstrated through manufacture and testing of hybrid circuits that PWs can be used to produce a variety of practical electronic circuits. A purality of different applications of PWs have been tested to show the universality of PWs in analogue and digital electronics. Results: Voltage dividers can be produced using a pair of PWs in series with an output voltage accurate to within 12%. PWs can also transmit analogue and digital data with a frequency of up to 19 kHz, which with the addition of a buffer, can drive high current circuits. We have demonstrated that PWs can last approximately two months, a 4 fold increase on previous literature. Protoplasmic tubes can be modified with the addition of conductive or magnetic nano-particles to provide changes in functionality. Conclusion This work has documented novel macro-scale data transmission through biological material; it has advanced the field of bio-electronics by providing a cheap and easy to grow conducting bio-material which may be used in future hybrid electronic technology.

cs.ET↗
arXiv2015

Canine Olfactory Differentiation of Cancer: A Review of the Literature

Numerous studies have attempted to demonstrate the olfactory ability of canines to detect several common cancer types from human bodily fluids, breath and tissue. Canines have been reported to detect bladder cancer (sensitivity of 0.63-0.73 and specificity of 0.64-0.92) and prostate cancer (sensitivity of 0.91-0.99 and specificity of 0.91-0.97) from urine; breast cancer (sensitivity of 0.88 and specificity of 0.98) and lung cancer (sensitivity 0.56-0.99 and specificity of 8.30-0.99) on breath and colorectal cancer from stools (sensitivity of 0.91-0.97 and specificity of 0.97-0.99). The quoted figures of sensitivity and specificity across differing studies demonstrate that in many cases results are variable from study to study; this raises questions about the reproducibility of methodology and study design which we have identified herein. Furthermore in some studies the controls used have resulted in differentiation of samples which are of limited use for clinical diagnosis. These studies provide some evidence that cancer gives rise to different volatile organic compounds (VOCs) compared to healthy samples. Whilst canine detection may be unsuitable for clinical implementation they can, at least, provide inspiration for more traditional laboratory investigations.

q-bio.TO↗
arXiv2015

Evolving Spiking Networks with Variable Resistive Memories

Neuromorphic computing is a brainlike information processing paradigm that requires adaptive learning mechanisms. A spiking neuro-evolutionary system is used for this purpose; plastic resistive memories are implemented as synapses in spiking neural networks. The evolutionary design process exploits parameter self-adaptation and allows the topology and synaptic weights to be evolved for each network in an autonomous manner. Variable resistive memories are the focus of this research; each synapse has its own conductance profile which modifies the plastic behaviour of the device and may be altered during evolution. These variable resistive networks are evaluated on a noisy robotic dynamic-reward scenario against two static resistive memories and a system containing standard connections only. Results indicate that the extra behavioural degrees of freedom available to the networks incorporating variable resistive memories enable them to outperform the comparative synapse types.

cs.NE↗
arXiv2014

Slime Mould Memristors

In laboratory experiments we demonstrate that protoplasmic tubes of acellular slime mould \emph{Physarum polycephalum} show current versus voltage profiles consistent with memristive systems and that the effect is due to the living protoplasm of the mould. This complements previous findings on memristive properties of other living systems (human skin and blood) and contributes to development of self-growing bio-electronic circuits. Distinctive asymmetric $V$-$I$ curves which were occasionally observed when the internal current is on the same order as the driven current, are well-modelled by the concept of active memristors.

cs.ET↗
arXiv2014

Sensory fusion in Physarum polycephalum and implementing multi-sensory functional computation

Surface electrical potential and observational growth recordings were made of a protoplasmic tube of the slime mould Physarum polycephalum in response to a multitude of stimuli with regards to sensory fusion or multisensory integration. Each stimulus was tested alone and in combination in order to evaluate for the first time the effect that multiple stimuli have on the frequency of streaming oscillation. White light caused a decrease in frequency whilst increasing the temperature and applying a food source in the form of oat flakes both increased the frequency. Simultaneously stimulating P. polycephalum with light and oat flake produced no net change in frequency, while combined light and heat stimuli showed an increase in frequency smaller than that observed for heat alone. When the two positive stimuli, oat flakes and heat, were combined, there was a net increase in frequency similar to the cumulative increases caused by the individual stimuli. Boolean logic gates were derived from the measured frequency change.

cs.ET↗
arXiv2014

Emergent Spiking in Non-Ideal Memristor Networks

Memristors have uses as artificial synapses and perform well in this role in simulations with artificial spiking neurons. Our experiments show that memristor networks natively spike and can exhibit emergent oscillations and bursting spikes. Networks of near-ideal memristors exhibit behaviour similar to a single memristor and combine in circuits like resistors do. Spiking is more likely when filamentary memristors are used or the circuits have a higher degree of compositional complexity (i.e. a larger number of anti-series or anti-parallel interactions). 3-memristor circuits with the same memristor polarity (low compositional complexity) are stabilised and do not show spiking behaviour. 3-memristor circuits with anti-series and/or anti-parallel compositions show richer and more complex dynamics than 2-memristor spiking circuits. We show that the complexity of these dynamics can be quantified by calculating (using partial auto-correlation functions) the minimum order auto-regression function that could fit it. We propose that these oscillations and spikes may be similar phenomena to brainwaves and neural spike trains and suggest that these behaviours can be used to perform neuromorphic computation.

cond-mat.mtrl-sci↗
arXiv2014

Does the D.C. Response of Memristors Allow Robotic Short-Term Memory and a Possible Route to Artificial Time Perception?

Time perception is essential for task switching, and in the mammalian brain appears alongside other processes. Memristors are electronic components used as synapses and as models for neurons. The d.c. response of memristors can be considered as a type of short-term memory. Interactions of the memristor d.c. response within networks of memristors leads to the emergence of oscillatory dynamics and intermittent spike trains, which are similar to neural dynamics. Based on this data, the structure of a memristor network control for a robot as it undergoes task switching is discussed and it is suggested that these emergent network dynamics could improve the performance of role switching and learning in an artificial intelligence and perhaps create artificial time perception.

cs.RO↗
arXiv2014

The Short-term Memory (D.C. Response) of the Memristor Demonstrates the Causes of the Memristor Frequency Effect

A memristor is often identified by showing its distinctive pinched hysteresis curve and testing for the effect of frequency. The hysteresis size should relate to frequency and shrink to zero as the frequency approaches infinity. Although mathematically understood, the material causes for this are not well known. The d.c. response of the memristor is a decaying curve with its own timescale. We show via mathematical reasoning that this decaying curve when transformed to a.c. leads to the frequency effect by considering a descretized curve. We then demonstrate the validity of this approach with experimental data from two different types of memristors.

cs.ET↗
arXiv2014

Is Spiking Logic the Route to Memristor-Based Computers?

Memristors have been suggested as a novel route to neuromorphic computing based on the similarity between neurons (synapses and ion pumps) and memristors. The D.C. action of the memristor is a current spike, which we think will be fruitful for building memristor computers. In this paper, we introduce 4 different logical assignations to implement sequential logic in the memristor and introduce the physical rules, summation, `bounce-back', directionality and `diminishing returns', elucidated from our investigations. We then demonstrate how memristor sequential logic works by instantiating a NOT gate, an AND gate and a Full Adder with a single memristor. The Full Adder makes use of the memristor's memory to add three binary values together and outputs the value, the carry digit and even the order they were input in.

cs.ET↗
arXiv2014

Boolean Logic Gates From A Single Memristor Via Low-Level Sequential Logic

By using the memristor's memory to both store a bit and perform an operation with a second input bit, simple Boolean logic gates have been built with a single memristor. The operation makes use of the interaction of current spikes (occasionally called current transients) found in both memristors and other devices. The sequential time-based logic methodology allows two logical input bits to be used on a one-port by sending the bits separated in time. The resulting logic gate is faster than one relying on memristor's state switching, low power and requires only one memristor. We experimentally demonstrate working OR and XOR gates made with a single flexible Titanium dioxide sol-gel memristor.

cs.ET↗
arXiv2014

Calculating Voronoi diagrams using simple chemical reactions

This paper overviews work on the use of simple chemical reactions to calculate Voronoi diagrams and undertake other related geometric calculations. This work highlights that this type of specialised chemical processor is a model example of a parallel processor. For example increasing the complexity of the input data within a given area does not increase the computation time. These processors are also able to calculate two or more Voronoi diagrams in parallel. Due to the specific chemical reactions involved and the relative strength of reaction with the substrate (and cross-reactivity with the products) these processors are also capable of calculating Voronoi diagrams sequentially from distinct chemical inputs. The chemical processors are capable of calculating a range of generalised Voronoi diagrams (either from circular drops of chemical or other geometric shapes made from adsorbent substrates soaked in reagent), skeletonisation of planar shapes and weighted Voronoi diagrams (e.g. additively weighted Voronoi diagrams, Multiplicitavely weighted Crystal growth Voronoi diagrams). The paper will also discuss some limitations of these processors. These chemical processors constitute a class of pattern forming reactions which have parallels with those observed in natural systems. It is possible that specialised chemical processors of this general type could be useful for synthesising functional structured materials.

nlin.PS↗
arXiv2013

The effect of changing electrode metal on solution-processed flexible titanium dioxide memristors

Flexible solution processed memristors show different behaviour dependent on the choice of electrode material. Use of gold for both electrodes leads to switchable WORM (Write Once Read Many times) resistive devices. Use of aluminium for both electrodes increases the richness of behaviour allowing both curved and triangular memristive switching resistance memories. A comparison device with an aluminium bottom electrode and gold top electrode only exhibited significant memristive resistance switching when the aluminium electrode was the cathode, suggesting that the electrode is acting as a source/sink of oxygen anions. When the gold electrode was the cathode this electrode was deformed by oxygen evolution. These results demonstrate that aluminium is helpful for stabilising and promoting memristive behaviour in sol-gel TiO$_2$ devices and that changing electrodes from aluminium to gold creates fundamentally different device characteristics.

cond-mat.mtrl-sci↗
arXiv2013

Routing of Physarum polycephalum signals using simple chemicals

In previous work the chemotaxis towards simple organic chemicals was assessed. We utilise the knowledge gained from these chemotactic assays to route Physarum polycephalum at a series of junctions. By applying chemical inputs at a simple T-junction we were able to reproducibly control the path taken by the plasmodium of P. Polycephalum. Where the chemoattractant farnesene was used at one input a routed signal could be reproducibly generated i.e. P. Polycephalum moves towards the source of chemoattractant. Where the chemoattractant was applied at both inputs the signal was reproducibly split. If a chemorepellent was used then the signal was reproducibly suppressed. If no chemical input was used in the simple circuit then a random signal was generated, whereby P. Polycephalum would move towards one output at the junction, but the direction was randomly selected. We extended this study to a more complex series of T-junctions to explore further the potential of routing P. Polycephalum. Although many of the circuits were completed effectively, any errors from the implementation of the simple T-junction were magnified. There were also issues with cascading effects through multiple junctions. For example signal splitting could be reproducibly initiated at the first junction but not at subsequent junctions. This work highlights the potential for exploiting chemotaxis to achieve complex and reliable routing of P. Polycephalum signals. This may be useful in implementing computing algorithms, design of autonomous robots and directed material synthesis. In additional experiments we showed that the application of chemoattractant compounds at specific locations on a homogeneous substrate could be used to reliably control the spatial configuration of P. Polycephalum. This may have applications in implementing geometric calculations and in robot navigation tasks such as mapping chemical plumes.

cs.ET↗
arXiv2013

On the internalisation, intraplasmodial carriage and excretion of metallic nanoparticles in the slime mould Physarum polycephalum

The plasmodium of Physarum polycephalum is a large single cell visible with the naked eye. When inoculated on a substrate with attractants and repellents the plasmodium develops optimal networks of protoplasmic tubes which span sites of attractants (i.e. nutrients) yet avoid domains with a high nutrient concentration. It should therefore be possible to program the plasmodium towards deterministic adaptive transformation of internalised nano- and micro-scale materials. In laboratory experiments with magnetite nanoparticles and glass micro-spheres coated with silver metal we demonstrate that the plasmodium of P. polycephalum can propagate the nano-scale objects using a number of distinct mechanisms including endocytosis, transcytosis and dragging. The results of our experiments could be used in the development of novel techniques targeted towards the growth of metallised biological wires and hybrid nano- and micro-circuits.

cs.ET↗
arXiv2013

Analysis of the volatiles in the headspace above the plasmodium and sporangia of the slime mould (Physarum polycephalum) by SPME-GCMS

Solid phase micro-extraction (SPME) coupled with Gas Chromatography Mass Spectrometry (GC-MS) was used to extract and analyse the volatiles in the headspace above the plasmodial and sporulating stages of the slime mould Physarum Polycephalum. In total 115 compounds were identified from across a broad range of chemical classes. Although more (87) volatile organic compounds (VOCs) were identified when using a higher incubation temperature of 75oC, a large number of compounds (79) were still identified at the lower extraction temperature of 30oC and where the plasmodial stage was living. Far fewer compounds were extracted after sporulation at the two extraction temperatures. There were some marked differences between the VOCs identified in the plasmodial stage and after sporulation. In particular the nitrogen containing compounds acetonitrile, pyrrole, 2, 5-dimethyl-pyrazine and trimethyl pyrazine seemed to be associated with the sporulating stage. There were many compounds associated predominantly with the plasmodial stage including a number of furans and alkanes. Interestingly, a number of known fungal metabolites were identified including 1-octen-3-ol, 3-octanone, 1-octen-3-one, 3-octanol. In addition known metabolites of cyanobacteria and actinobacteria in particular geosmin was identified in the headspace. Volatile metabolites that had previously been identified as having a positive chemotactic response to the plasmodial stage of P. polycephalum were also identified including β-farnesene, β-myrcene, limonene and 3-octanone. This study constitutes the first comprehensive analysis of the headspace volatiles emitted from Physarum Polycephalum. Further work to understand the origin and function of the volatiles identified is required.

physics.bio-ph↗
arXiv2013

Beyond Markov Chains, Towards Adaptive Memristor Network-based Music Generation

We undertook a study of the use of a memristor network for music generation, making use of the memristor's memory to go beyond the Markov hypothesis. Seed transition matrices are created and populated using memristor equations, and which are shown to generate musical melodies and change in style over time as a result of feedback into the transition matrix. The spiking properties of simple memristor networks are demonstrated and discussed with reference to applications of music making. The limitations of simulating composing memristor networks in von Neumann hardware is discussed and a hardware solution based on physical memristor properties is presented.

cs.ET↗
arXiv2013

Comparison of Ant-Inspired Gatherer Allocation Approaches using Memristor-Based Environmental Models

Memristors are used to compare three gathering techniques in an already-mapped environment where resource locations are known. The All Site model, which apportions gatherers based on the modeled memristance of that path, proves to be good at increasing overall efficiency and decreasing time to fully deplete an environment, however it only works well when the resources are of similar quality. The Leaf Cutter method, based on Leaf Cutter Ant behaviour, assigns all gatherers first to the best resource, and once depleted, uses the All Site model to spread them out amongst the rest. The Leaf Cutter model is better at increasing resource influx in the short-term and vastly out-performs the All Site model in a more varied environments. It is demonstrated that memristor based abstractions of gatherer models provide potential methods for both the comparison and implementation of agent controls.

cs.NE↗