Two-dimensional Footprint Research Articles

Footprints of Geodesics in Persistent Homology

Given a metric space X and a subspace $$A\subset X$$ , we prove that A can generate various algebraic elements in persistent homology of X. We call such elements (algebraic) footprints of A. Our results imply that footprints typically appear in dimensions above $$\dim (A)$$ . Higher dimensional persistent homology thus encodes lower dimensional geometric features of X. We pay special attention to a specific type of geodesics in a geodesic surface X called geodesic circles. We explain how they may generate non-trivial odd-dimensional and two-dimensional footprints. In particular, we can detect even some contractible geodesics using two- and three-dimensional persistent homology. This provides a link between persistent homology and the length spectrum in Riemannian geometry.

Unsteady shallow meandering flows in rectangular reservoirs: A modal analysis of URANS modelling

Shallow flows are common in natural and human-made environments. Even for simple rectangular shallow reservoirs, recent laboratory experiments show that the developing flow fields are particularly complex, involving large-scale turbulent structures. For specific combinations of reservoir size and hydraulic conditions, a meandering jet can be observed. While some aspects of this pseudo-2D flow pattern can be reproduced using a 2D numerical model, new 3D simulations, based on the unsteady Reynolds-Averaged Navier-Stokes equations, show consistent advantages as presented herein. A Proper Orthogonal Decomposition was used to characterize the four most energetic modes of the meandering jet at the free surface level, allowing comparison against experimental data and 2D (depth-averaged) numerical results. Three different isotropic eddy viscosity models (RNG k-ε, k-ε, k-ω) were tested. The 3D models accurately predicted the frequency of the modes, whereas the amplitudes of the modes and associated energy were damped for the friction-dominant cases and augmented for non-frictional ones. The performance of the three turbulence models remained essentially similar, with slightly better predictions by RNG k-ε model in the case with the highest Reynolds number. Finally, the Q-criterion was used to identify vortices and study their dynamics, assisting on the identification of the differences between: i) the three-dimensional phenomenon (here reproduced), ii) its two-dimensional footprint in the free surface (experimental observations) and iii) the depth-averaged case (represented by 2D models).

Sexing white 2D footprints using convolutional neural networks.

Footprints are left, or obtained, in a variety of scenarios from crime scenes to anthropological investigations. Determining the sex of a footprint can be useful in screening such impressions and attempts have been made to do so using single or multi landmark distances, shape analyses and via the density of friction ridges. Here we explore the relative importance of different components in sexing two-dimensional foot impressions namely, size, shape and texture. We use a machine learning approach and compare this to more traditional methods of discrimination. Two datasets are used, a pilot data set collected from students at Bournemouth University (N = 196) and a larger data set collected by podiatrists at Sheffield NHS Teaching Hospital (N = 2677). Our convolutional neural network can sex a footprint with accuracy of around 90% on a test set of N = 267 footprint images using all image components, which is better than an expert can achieve. However, the quality of the impressions impacts on this success rate, but the results are promising and in time it may be possible to create an automated screening algorithm in which practitioners of whatever sort (medical or forensic) can obtain a first order sexing of a two-dimensional footprint.

All-Optical Electrophysiology for High-Throughput Functional Characterization of a Human iPSC-Derived Motor Neuron Model of ALS.

SummaryHuman induced pluripotent stem cell (iPSC)-derived neurons are an attractive substrate for modeling disease, yet the heterogeneity of these cultures presents a challenge for functional characterization by manual patch-clamp electrophysiology. Here, we describe an optimized all-optical electrophysiology, “Optopatch,” pipeline for high-throughput functional characterization of human iPSC-derived neuronal cultures. We demonstrate the method in a human iPSC-derived motor neuron (iPSC-MN) model of amyotrophic lateral sclerosis (ALS). In a comparison of iPSC-MNs with an ALS-causing mutation (SOD1 A4V) with their genome-corrected controls, the mutants showed elevated spike rates under weak or no stimulus and greater likelihood of entering depolarization block under strong optogenetic stimulus. We compared these results with numerical simulations of simple conductance-based neuronal models and with literature results in this and other iPSC-based models of ALS. Our data and simulations suggest that deficits in slowly activating potassium channels may underlie the changes in electrophysiology in the SOD1 A4V mutation.

Estimation of stature from foot outline in adult Malaysian Malayalee ethnics for forensic investigation

Identification is a key component in any forensic investigation. Estimation of stature is an identifying characteristics to solve the crime. Foot impression is known to be a valuable scientific evidence encountered in the scenes of crime. Examination of footprint helps in estimation of stature of an individual since there is a strong relationship exists between foot impression and stature. There are people who still have the habit of walking barefoot in Asian countries like Malaysia, Sri Lanka, India, Thailand and Indonesia. The hard surfaces produce two-dimensional footprints while foot outline provides the size parameters of the fleshed bare foot and also represents the boundaries of the foot’s impression in soft soil, mud, or any other substances that produces a three-dimensional foot impression. It is shown that very limited studies were conducted on stature estimation from foot outline measurements. It is important to note that racial and cultural aspects of foot morphology must be considered while conducting the foot impression study. Researchers have cautioned that regression equations derived to estimate stature from foot impression for a particular population is erroneous to apply for other populations. Thus the present investigation is aimed to derive linear regression equations to estimate stature from foot outlines of Malaysian Malayalee ethnics.

A 3-D Folded Dipole Antenna Array for Far-Field Electromagnetic Energy Transfer

We present the concept and design of vertically stacked electromagnetic energy-harvesting system using folded dipole antennas. The proposed system is composed of stacked rectenna arrays or panels that are connected in various ways to channel the collected ac power to a single dc load. We show through experiments that by vertically stacking rectenna panels, the power collected per footprint is enhanced significantly. In fact, an improvement of up to 5 times is achieved in comparison to a single panel occupying the same two-dimensional footprint.

Stature estimation from the anthropometric measurements of foot outline in adult indigenous Melanau ethnics of East Malaysia by regression analysis

A person’s stature is an identifying characteristic in forensic investigation. Footprint is the one of the valuable physical evidence encountered in the crime scenes. Analysis of footprints helps in estimation of an individual’s stature because of the existence of strong correlation between foot impression and height. Foot impressions are still found at crime scenes, since offenders often tend to remove their footwear either to avoid noise or to gain better grip in climbing walls, etc., while entering or exiting. In Asian countries like India, Malaysia, Sri Lanka, Thailand, Indonesia, there are people who still have the habit of walking barefoot. The footprint provides the size dimensions of the foot’s plantar surface actually touching the floor or hard surface, which produces a two-dimensional footprint while foot outline provides the size parameters of the fleshed bare foot and also represents the boundaries of the foot’s impression in soft soil, mud, or any other substances that produces a three-dimensional footprint impression. The review of literature revealed that very limited studies were conducted on stature estimation from foot outline measurements. Most of the foot/foot impression studies have been conducted on mixed population. The researchers cautioned that racial and cultural aspects of foot morphology must be considered while conducting the foot impression study. In stature estimation using foot impression, formulae derived for a particular population is erroneous to apply for other populations. Hence the present study aims to derive population specific equations to estimate stature from foot outlines of indigenous Melanau ethnics of East Malaysia. Sri Lanka Journal of Forensic Medicine, Science & Law- December 2013;4(2):27-35 DOI: http://dx.doi.org/10.4038/sljfmsl.v4i2.6927

Formation, release and assembly of a non-evaporative photocurable liquid through micromolding and inkjet printing

This paper presents a hybrid method combining micromolding and inkjet printing for the formation of microparts at milli- to micrometer scales. Two-dimensional footprints of versatile shapes such as rotors and characters are first realized by micromolding. Then microdroplets are inkjet-printed into the micro-cavities of the micromolds, yielding three-dimensional formations of liquid with remarkable heights. Printed liquid of NOA 89 is photocurable for ultraviolet (UV) light, featuring 100% solids without the evaporation involved in solidification. After UV curing the liquid formations created solid and coherent textures with voids found through experiments. The shapes and morphologies of the formed parts are found to be uniform and smooth while using hydrophobic PDMS (polydimethysiloxane) as the material of the micromolds. Moreover, release of microparts from those molds is achievable by simple bending due to the elastomer property of PDMS. The molds and parts remain intact after separation. The assembly of the released parts of the rotors into the micro-channels of a PDMS fluidic chip is also demonstrated. Hence, the current method provides access to a cost-efficient manufacturing process of microparts with little waste as the micromolds can be reused via inkjet printing.

Reliability of a two-dimensional footprint measurement approach

Although footprint evidence can be taken from the scene of a crime, the science underpinning such measurement in forensic science has not been fully explored. A literature search revealed various measuring approaches, all of which demonstrated either little or no measurement rigour in terms of reliability. The aim of this study was to apply a robust measurement approach for testing the reliability of two-dimensional footprint impressions. Three dynamic and three static footprints were taken from the right foot of thirty female and thirty one male volunteers using the 'Inkless Shoeprint Kit'. The images were digitised. Lengths, widths and angles were measured using a selection of currently employed methods. An investigation of the reliability of the chosen measuring method suggested high intra-rater agreement: for example, the length measurement suggested an intraclass correlation coefficient (ICC) 0.99, 95% Confidence Interval (CI) -0.28 to 0.01, standard error of measurement (SEM) 0.07, Limits of Agreement (LOA) -0.91 to 0.65. Inter-rater reliability between three operators was also high: SEM ranged from 0.05 mm to 0.07 mm, ICC 0.99. Our study has established a reliable two-dimensional measuring technique that could be used for footprint comparison in further research.

Footprint issues in scintillometry over heterogeneous landscapes

Abstract. Scintillometry is widely recognized as a potential tool for obtaining spatially aggregated sensible heat fluxes at regional scales. Although many investigations have been made over contrasting component surfaces, few aggregation schemes consider footprint contributions. In this paper, an approach is presented to infer average sensible heat flux over a very heterogeneous landscape by using a large aperture scintillometer. The methodology is demonstrated on simulated data and tested on a time series of measurements obtained during the SPARC2004 experiment in Barrax, Spain. Results show that the two-dimensional footprint approach yields more accurate results of aggregated sensible heat flux than traditional methods.

Imaging large arrays of supported lipid bilayers with a macroscope

Herein, the authors present fluorescence resonance energy transfer (FRET) and two-dimensional protein saturation data acquired from spatially addressed arrays of solid supported lipid bilayers (SLBs). The SLB arrays were imaged with an epifluorescencetotal internal reflection macroscope. The macroscope allowed 1x imaging and had a relatively high numerical aperture (0.4). Such powerful light gathering and large field of view capabilities make it possible to simultaneously image dozens of addressed SLBs. Three experiments have been performed. First, a 9x7 array of supported lipid bilayer was fabricated and imaged in which each bilayer element was individually addressed. Second, a FRET assay was developed between Texas Red-DHPE (1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine) and NBD-PE (1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-n-(7-nitro-2-1,3-benzoxadiazol-4-yl)). The concentration of dye could be varied at each address and the value of the Forster radius (7.3+/-0.6 nm) was easily abstracted. Third, a ligandreceptor recognition assay was designed to show the two-dimensional number density of proteins which can be bound at saturation. It was found for the streptavidinbiotin pair that the protein saturated at the interface above 3 mol % biotin concentration. This corresponded to a two-dimensional footprint of 40 nm(2) for the streptavidin molecule. These results clearly open the door to using individually addressed bilayers for obtaining large amounts of biophysical data at the supported bilayeraqueous interface. Such abilities will be crucial to obtaining sufficient data for determining the interfacial mechanisms for a variety of membraneprotein interactions.