Canine-inspired Unidirectional Flows for Improving Memory Effects in Machine Olfaction.

A dog's nose differs from a human's in that air does not change direction but flows in a unidirectional path from inlet to outlet. Previous simulations showed that unidirectional flow through a dog's complex nasal passageways creates stagnant zones of trapped air. We hypothesize that these zones give the dog a "physical memory," which it may use to compare recent odors to past ones.

COVID-19 impact on maritime traffic and corresponding pollutant emissions. The case of the Port of Barcelona.

The impact of the SARS-CoV pandemic has gone well beyond health concerns, reaching the maritime industry. The study on the environmental impact of shipping industry during COVID-19 pandemic can provide useful insights to propose new management policies regarding shipping operations, both in-port and on the route. We present a case study centred in the Port of Barcelona covering a 30 nautical miles range in the period March to July 2020, during which different levels of restrictions and stringent lockdown measures were enforced.

How Did the COVID-19 Lockdown Affect Children and Adolescent's Well-Being: Spanish Parents, Children, and Adolescents Respond.

During the COVID-19 pandemic, lockdown strategies have been widely used to contain SARS-CoV-2 virus spread. Children and adolescents are especially vulnerable to suffering psychological effects as result of such measures. In Spain, children were enforced to a strict home lockdown for 42 days during the first wave.

mWISE: An Algorithm for Context-Based Annotation of Liquid Chromatography-Mass Spectrometry Features through Diffusion in Graphs.

Untargeted metabolomics using liquid chromatography coupled to mass spectrometry (LC-MS) allows the detection of thousands of metabolites in biological samples. However, LC-MS data annotation is still considered a major bottleneck in the metabolomics pipeline since only a small fraction of the metabolites present in the sample can be annotated with the required confidence level. Here, we introduce mWISE (metabolomics wise inference of speck entities), an R package for context-based annotation of LC-MS data.

Sniffing speeds up chemical detection by controlling air-flows near sensors.

Most mammals sniff to detect odors, but little is known how the periodic inhale and exhale that make up a sniff helps to improve odor detection. In this combined experimental and theoretical study, we use fluid mechanics and machine olfaction to rationalize the benefits of sniffing at different rates. We design and build a bellows and sensor system to detect the change in current as a function of odor concentration.

Polar Coding for Confidential Broadcasting.

A polar coding scheme is proposed for the Wiretap Broadcast Channel with two legitimate receivers and one eavesdropper. We consider a model in which the transmitter wishes to send the same private (non-confidential) message and the same confidential message reliably to two different legitimate receivers, and the confidential message must also be (strongly) secured from the eavesdropper. The coding scheme aims to use the optimal rate of randomness and does not make any assumption regarding the symmetry or degradedness of the channel.

Application of an Array of Metal-Oxide Semiconductor Gas Sensors in an Assistant Personal Robot for Early Gas Leak Detection.

This paper proposes the application of a low-cost gas sensor array in an assistant personal robot (APR) in order to extend the capabilities of the mobile robot as an early gas leak detector for safety purposes. The gas sensor array is composed of 16 low-cost metal-oxide (MOX) gas sensors, which are continuously in operation. The mobile robot was modified to keep the gas sensor array always switched on, even in the case of battery recharge.

A Practical Method to Estimate the Resolving Power of a Chemical Sensor Array: Application to Feature Selection.

A methodology to calculate analytical figures of merit is not well established for detection systems that are based on sensor arrays with low sensor selectivity. In this work, we present a practical approach to estimate the Resolving Power of a sensory system, considering non-linear sensors and heteroscedastic sensor noise. We use the definition introduced by Shannon in the field of communication theory to quantify the number of symbols in a noisy environment, and its version adapted by Gardner and Barlett for chemical sensor systems.

Learning of Chunking Sequences in Cognition and Behavior.

We often learn and recall long sequences in smaller segments, such as a phone number 858 534 22 30 memorized as four segments. Behavioral experiments suggest that humans and some animals employ this strategy of breaking down cognitive or behavioral sequences into chunks in a wide variety of tasks, but the dynamical principles of how this is achieved remains unknown. Here, we study the temporal dynamics of chunking for learning cognitive sequences in a chunking representation using a dynamical model of competing modes arranged to evoke hierarchical Winnerless Competition (WLC) dynamics.

Data set from chemical sensor array exposed to turbulent gas mixtures.

A chemical detection platform composed of 8 chemo-resistive gas sensors was exposed to turbulent gas mixtures generated naturally in a wind tunnel. The acquired time series of the sensors are provided. The experimental setup was designed to test gas sensors in realistic environments.

Dataset from chemical gas sensor array in turbulent wind tunnel.

The dataset includes the acquired time series of a chemical detection platform exposed to different gas conditions in a turbulent wind tunnel. The chemo-sensory elements were sampling directly the environment. In contrast to traditional approaches that include measurement chambers, open sampling systems are sensitive to dispersion mechanisms of gaseous chemical analytes, namely diffusion, turbulence, and advection, making the identification and monitoring of chemical substances more challenging.

Data set from gas sensor array under flow modulation.

Recent studies in neuroscience suggest that sniffing, namely sampling odors actively, plays an important role in olfactory system, especially in certain scenarios such as novel odorant detection. While the computational advantages of high frequency sampling have not been yet elucidated, here, in order to motivate further investigation in active sampling strategies, we share the data from an artificial olfactory system made of 16 MOX gas sensors under gas flow modulation. The data were acquired on a custom set up featured by an external mechanical ventilator that emulates the biological respiration cycle.

Chemical gas sensor array dataset.

To address drift in chemical sensing, an extensive dataset was collected over a period of three years. An array of 16 metal-oxide gas sensors was exposed to six different volatile organic compounds at different concentration levels under tightly-controlled operating conditions. Moreover, the generated dataset is suitable to tackle a variety of challenges in chemical sensing such as sensor drift, sensor failure or system calibration.

Chemical discrimination in turbulent gas mixtures with MOX sensors validated by gas chromatography-mass spectrometry.

Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow.

Estimation of the limit of detection using information theory measures.

Definitions of the limit of detection (LOD) based on the probability of false positive and/or false negative errors have been proposed over the past years. Although such definitions are straightforward and valid for any kind of analytical system, proposed methodologies to estimate the LOD are usually simplified to signals with Gaussian noise. Additionally, there is a general misconception that two systems with the same LOD provide the same amount of information on the source regardless of the prior probability of presenting a blank/analyte sample.

Two-dimensional wavelet transform feature extraction for porous silicon chemical sensors.

Designing reliable, fast responding, highly sensitive, and low-power consuming chemo-sensory systems has long been a major goal in chemo-sensing. This goal, however, presents a difficult challenge because having a set of chemo-sensory detectors exhibiting all these aforementioned ideal conditions are still largely un-realizable to-date. This paper presents a unique perspective on capturing more in-depth insights into the physicochemical interactions of two distinct, selectively chemically modified porous silicon (pSi) film-based optical gas sensors by implementing an innovative, based on signal processing methodology, namely the two-dimensional discrete wavelet transform.

Quality coding by neural populations in the early olfactory pathway: analysis using information theory and lessons for artificial olfactory systems.

In this article, we analyze the ability of the early olfactory system to detect and discriminate different odors by means of information theory measurements applied to olfactory bulb activity images. We have studied the role that the diversity and number of receptor neuron types play in encoding chemical information. Our results show that the olfactory receptors of the biological system are low correlated and present good coverage of the input space.

Optical label-free nanoplasmonic biosensing using a vertical-cavity surface-emitting laser and charge-coupled device.

We present a compact platform for biochemosensing based on the combination of a vertical-cavity surface-emitting laser (VCSEL) light source, microelectromechanical systems (MEMS)-based microoptics, a specially designed nanoplasmonic sensing chip, and charge-coupled device (CCD) detector. The platform does not require any spectral analyzer for signal evaluation, showing good promise for facile integration, neither does it use any microscope setup for the signal collection or imaging. The analytical capabilities of the developed biochemosensing platform are demonstrated by evaluation of the protein-substrate (biotinylated bovine serum albumin-gold) and the protein-protein (biotin-NeutrAvidin) binding kinetics, which is further compared to detection based on conventional optical extinction spectroscopy.

X-ray diffraction analysis of internal wool lipids.

Polarised optical microscopy (POM) and X-ray diffraction techniques were applied to intercellular lipids extracted from wool to study their structural arrangement in order to determine their role in the diffusion properties of wool fibre. Intercellular wool lipids (IWL) arranged as concentrated liposomes were shown to be a good intercellular lipid model, allowing their study by X-ray diffraction techniques. The results confirm that intercellular lipids of wool fibre are organised in a lamellar structure of 5.

Efficacy of stratum corneum lipid supplementation on human skin.

Recent studies suggest that supplementing intercellular lipids of the stratum corneum in ageing populations or in people with dry skin can stimulate the functioning of the skin. This work lends support to the reinforcement capacity of two different stratum corneum lipid mixtures (synthetic stratum corneum lipid mixtures, SSCL, and internal wool lipid extracts, IWL) formulated as liposomes on healthy skin of two differently aged groups of individuals. Protection of healthy skin against detergent-induced dermatitis was evaluated.

Influence of cholesterol on liposome fluidity by EPR. Relationship with percutaneous absorption.

The influence of liposome composition on bilayer fluidity and its effect on the percutaneous absorption into the skin were investigated. Liposomes formed with saturated or unsaturated phospholipids (H-PC or PC) with varying amounts of cholesterol were prepared and their penetration behaviour into the stratum corneum was followed up by means of the stripping method. The order and dynamics of the hydrophobic domain of the vesicles were studied using electron paramagnetic resonance (EPR) methodology.

Effect of internal wool lipid liposomes on skin repair.

Intercellular lipids of the stratum corneum (SC) play a crucial role in keeping an optimal skin barrier function and in regulating the water-holding capacity. Recently, the internal lipids have been extracted from wool fibre. This lipid extract has a composition similar to that of the SC lipids.

Motion estimation using higher order statistics.

The objective of this paper is to introduce a fourth-order cost function of the displaced frame difference (DFD) capable of estimating motion even for small regions or blocks. Using higher than second-order statistics is appropriate in case the image sequence is severely corrupted by additive Gaussian noise. Some results are presented and compared to those obtained from the mean kurtosis and the mean square error of the DFD.