The influence of internal pressure and neuromuscular agents on biomechanics: an empirical and multi-compartmental modelling study.

The function of a specific tissue and its biomechanics are interdependent, with pathologies or ageing often being intertwined with structural decline. The biomechanics of , a model organism widely used in pharmacological and ageing research, has been established as biomarker for healthy ageing. However, the properties of the constituent tissues, and their contribution to the overall mechanical characteristics of the organism, remain relatively unknown.

Perception of Soft Objects in Virtual Environments Under Conflicting Visual and Haptic Cues.

In virtual/augmented/mixed reality (VR/AR/MR) applications, rendering soft virtual objects using a hand-held haptic device is challenging due to the anatomical restrictions of the hand and the ungrounded nature of the design, which affect the selection of actuators and sensors and hence limit the resolution and range of forces displayed by the device. We developed a cable-driven haptic device for rendering the net forces involved in grasping and squeezing 3D virtual compliant (soft) objects being held between the index finger and thumb only. Using the proposed device, we investigate the perception of soft objects in virtual environments.

Data-driven malaria prevalence prediction in large densely populated urban holoendemic sub-Saharan West Africa.

Over 200 million malaria cases globally lead to half-million deaths annually. The development of malaria prevalence prediction systems to support malaria care pathways has been hindered by lack of data, a tendency towards universal "monolithic" models (one-size-fits-all-regions) and a focus on long lead time predictions. Current systems do not provide short-term local predictions at an accuracy suitable for deployment in clinical practice.

Expert-level automated malaria diagnosis on routine blood films with deep neural networks.

Over 200 million malaria cases globally lead to half a million deaths annually. Accurate malaria diagnosis remains a challenge. Automated imaging processing approaches to analyze Thick Blood Films (TBF) could provide scalable solutions, for urban healthcare providers in the holoendemic malaria sub-Saharan region.

Mechanical properties measured by atomic force microscopy define health biomarkers in ageing C. elegans.

Genetic and environmental factors are key drivers regulating organismal lifespan but how these impact healthspan is less well understood. Techniques capturing biomechanical properties of tissues on a nano-scale level are providing new insights into disease mechanisms. Here, we apply Atomic Force Microscopy (AFM) to quantitatively measure the change in biomechanical properties associated with ageing Caenorhabditis elegans in addition to capturing high-resolution topographical images of cuticle senescence.

Coding source localization through inter-spike delay: modelling a cluster of Pacinian Corpuscles using time-division multiplexing approach.

The Pacinian Corpuscle (PC) is the most sensitive mechanoreceptor in the human body found in clusters of two or three. We extended our previous model of an isolated-PC to a cluster-PC focussing on relative spike delay and displacement threshold for understanding how the stimulus location is coded. In our model, two PCs with Gaussian overlapping receptive fields are arranged beneath the skin model.

Three-dimensional behavioural phenotyping of freely moving C. elegans using quantitative light field microscopy.

Behavioural phenotyping of model organisms is widely used to investigate fundamental aspects of organism biology, from the functioning of the nervous system to the effects of genetic mutations, as well as for screening new drug compounds. However, our capacity to observe and quantify the full range and complexity of behavioural responses is limited by the inability of conventional microscopy techniques to capture volumetric image information at sufficient speed. In this article we describe how combining light field microscopy with computational depth estimation provides a new method for fast, quantitative assessment of 3D posture and movement of the model organism Caenorhabditis elegans (C.

Natural Infection of C. elegans by an Oomycete Reveals a New Pathogen-Specific Immune Response.

In its natural habitat, the nematode Caenorhabditis elegans encounters a plethora of other organisms, including many that are pathogenic [1, 2]. The study of interactions between C. elegans and various pathogens has contributed to characterizing key mechanisms of innate immunity [2-4].

Determining the biomechanics of touch sensation in C. elegans.

The sense of touch is a fundamental mechanism that nearly all organisms use to interact with their surroundings. However, the process of mechanotransduction whereby a mechanical stimulus gives rise to a neuronal response is not well understood. In this paper we present an investigation of the biomechanics of touch using the model organism C.

Nano-mechanical single-cell sensing of cell-matrix contacts.

Extracellular protein matrices provide a rigidity interface exhibiting nano-mechanical cues that guide cell growth and proliferation. Cells sense such cues using actin-rich filopodia extensions which encourage favourable cell-matrix contacts to recruit more actin-mediated local forces into forming stable focal adhesions. A challenge remains in identifying and measuring these local cellular forces and in establishing empirical relationships between them, cell adhesion and filopodia formation.

In-vivo high resolution AFM topographic imaging of Caenorhabditis elegans reveals previously unreported surface structures of cuticle mutants.

Atomic force microscopy (AFM) is a powerful method for topographic imaging of surfaces with nanometer resolution. AFM offers significant advantages over scanning electron microscopy (SEM) including the acquisition of quantitative 3D-images and biomechanical information. More importantly, for in-vivo biological imaging, AFM does not require sample dehydration/labeling.

Investigation of mechanosensation in C. elegans using light field calcium imaging.

We describe a new experimental approach to investigate touch sensation in the model organism C. elegans using light field deconvolution microscopy. By combining fast volumetric image acquisition with controlled indentation of the organism using a high sensitivity force transducer, we are able to simultaneously measure activity in multiple touch receptor neurons expressing the calcium ion indicator GCaMP6s.

Viscoelastic characterization of the primate finger pad in vivo by microstep indentation and three-dimensional finite element models for tactile sensation studies.

When we touch an object, surface loads imposed on the skin are transmitted to thousands of specialized nerve endings (mechanoreceptors) embedded within the skin. These mechanoreceptors transduce the mechanical signals imposed on them into a neural code of the incident stimuli, enabling us to feel the object. To understand the mechanisms of tactile sensation, it is critical to understand the relationship between the applied surface loads, mechanical state at the mechanoreceptor locations, and transduced neural codes.

Vibrotactile sensitivity threshold: nonlinear stochastic mechanotransduction model of the Pacinian Corpuscle.

Based on recent discoveries of stretch and voltage activated ion channels in the receptive area of the Pacinian Corpuscle (PC), this paper describes a two-stage mechanotransduction model of its near threshold Vibrotactile (VT) sensitivity valid over 10 Hz to a few kHz. The model is based on the nonlinear and stochastic behavior of the ion channels represented as dependent charge sources loaded with membrane impedance. It simulates the neural response of the PC considering the morphological and statistical properties of the receptor potential and action potential with the help of an adaptive relaxation pulse frequency modulator.

Multiscale layered biomechanical model of the pacinian corpuscle.

This paper describes a multiscale analytical model of the lamellar structure and the biomechanical response of the Pacinian Corpuscle (PC). In order to analyze the contribution of the PC lamellar structure for detecting high-frequency vibrotactile (VT) stimuli covering 10 Hz to a few kHz, the model response is studied against trapezoidal and sinusoidal stimuli. The model identifies a few generalizable features of the lamellar structure which makes it scalable for different sizes of PC with different number of lamellae.

Rehabilitation Program Integrating Virtual Environment to Improve Orientation and Mobility Skills for People Who Are Blind.

This paper presents the integration of a virtual environment (BlindAid) in an orientation and mobility rehabilitation program as a training aid for people who are blind. BlindAid allows the users to interact with different virtual structures and objects through auditory and haptic feedback. This research explores if and how use of the BlindAid in conjunction with a rehabilitation program can help people who are blind train themselves in familiar and unfamiliar spaces.

Human haptic perception is interrupted by explorative stops of milliseconds.

Introduction: The explorative scanning movements of the hands have been compared to those of the eyes. The visual process is known to be composed of alternating phases of saccadic eye movements and fixation pauses. Descriptive results suggest that during the haptic exploration of objects short movement pauses occur as well.

Beaming into the rat world: enabling real-time interaction between rat and human each at their own scale.

Immersive virtual reality (IVR) typically generates the illusion in participants that they are in the displayed virtual scene where they can experience and interact in events as if they were really happening. Teleoperator (TO) systems place people at a remote physical destination embodied as a robotic device, and where typically participants have the sensation of being at the destination, with the ability to interact with entities there. In this paper, we show how to combine IVR and TO to allow a new class of application.

Newly blind persons using virtual environment system in a traditional orientation and mobility rehabilitation program: a case study.

This paper presents a virtual reality system (the BlindAid) developed for orientation and mobility training of people who are newly blind. The BlindAid allows users to interact with different virtual structures and objects via auditory and haptic feedback. This case study aims to examine if and how the BlindAid, in conjunction with a traditional rehabilitation programme, can help people who are newly blind develop new orientation and mobility methods.

Developments in brain-machine interfaces from the perspective of robotics.

Many patients suffer from the loss of motor skills, resulting from traumatic brain and spinal cord injuries, stroke, and many other disabling conditions. Thanks to technological advances in measuring and decoding the electrical activity of cortical neurons, brain-machine interfaces (BMI) have become a promising technology that can aid paralyzed individuals. In recent studies on BMI, robotic manipulators have demonstrated their potential as neuroprostheses.

An efficient soft tissue characterization algorithm from in vivo indentation experiments for medical simulation.

Background: Realistic virtual reality surgical training simulators require an accurate biomechanical model of in vivo soft tissue behaviour. One of the challenges in modelling is to characterize soft tissue properties incorporating the experimental measurements of organ behaviour.

Method: Organ measurements were collected from intra-abdominal organs of pigs, using a robotic indenter and a force transducer.

The muscle activation method: an approach to impedance control of brain-machine interfaces through a musculoskeletal model of the arm.

Current demonstrations of brain-machine interfaces (BMIs) have shown the potential for controlling neuroprostheses under pure motion control. For interaction with objects, however, pure motion control lacks the information required for versatile manipulation. This paper investigates the idea of applying impedance control in a BMI system.

Virtual surgery simulation for medical training using multi-resolution organ models.

Background: Real-time simulation of organ deformation is one of the biggest challenges in virtual surgery, due to the conflicting requirements of real-time interactivity and simulation realism. In this paper we propose a method to overcome this challenge by introducing a multi-resolution modelling technique.

Methods: In our approach a reasonably coarse global model is locally enhanced, using a mesh subdivision and smoothing algorithm.

In vivo mechanical behavior of intra-abdominal organs.

For realistic surgical simulation in a virtual environment, in vivo material properties of biological tissues are required for simulating the deformations and the reaction forces from the tool-tissue interactions. In this paper, the in vivo static and dynamic mechanical behavior of the liver and lower esophagus of pigs were presented both in linear and nonlinear regions under compressive and shear indentations. A robotic device was programmed to function as a mechanical stimulator with a 2-mm flat-tipped cylindrical probe attached to its tip.

Continuous shared control for stabilizing reaching and grasping with brain-machine interfaces.

Research on brain-machine interfaces (BMI's) is directed toward enabling paralyzed individuals to manipulate their environment through slave robots. Even for able-bodied individuals, using a robot to reach and grasp objects in unstructured environments can be a difficult telemanipulation task. Controlling the slave directly with neural signals instead of a hand-master adds further challenges, such as uncertainty about the intended trajectory coupled with a low update rate for the command signal.