Speeding up active mesh segmentation by local termination of nodes.

This article outlines a procedure for speeding up segmentation of images using active mesh systems. Active meshes and other deformable models are very popular in image segmentation due to their ability to capture weak or missing boundary information; however, where strong edges exist, computations are still done after mesh nodes have settled on the boundary. This can lead to extra computational time whilst the system continues to deform completed regions of the mesh. We propose a local termination procedure, reducing these unnecessary computations and speeding up segmentation time with minimal loss of quality

Biomechanical Foot Guidance Linkage

A gait replication apparatus can include a scalable mechanical mechanism configured to replicate different gaits . The scalable mechanical mechanism can include , for example , a four - bar linkage , a pantograph , a cam / Scotch - yoke mechanism , and so forth . In some embodiments , the mechanical mechanism includes a beam rotating about an axis passing proximate to its center , with a foot pedal slidably coupled with the beam , and a timing chain / belt or cable pulley - pair coupled with the foot pedal and looped about the beam . A method can include decomposing a foot path defined by Cartesian coordinates into polar coordinates , and providing a mechanical support for a foot , where a first mechanism controls an angular position of the mechanical support with respect to a reference frame , and a second mechanism controls a radial distance of the mechanical support from the reference frame

INTELLIGENT MODULAR TOOL FOR EMERGENCY SURGICAL TREATMENT DURING PAYLOADCRITICAL MISSIONS

During any extended mission to an extreme environment (i.e. the International Space Station, a lunar base or a manned mission to Mars) the chances of an otherwise minor mJury becoming life threatening grow to be significant. In order to address these concerns, equipment must be provided to diagnose and treat a wide range of possible afflictions while direct contact with Earth-based physicians is impossible. Minimally invasive surgery (MIS) is an excellent treatment option due to its history of decreasing trauma in patients and speeding recovery. In an effort to provide the maximum functionality for any given MIS procedure, an intelligent modular surgical system has been designed and is being further refined to assist surgeons and other practitioners during medical procedures without necessitating the inclusion of many different instruments. The overall design approach was to identify the functions of existing technology and then to design a device that combined functionalities whenever possible to minimize the overall complexity of the design. The intelligence in the design is intended to make finding instruments easier for the individual performing the surgical procedure rather than replace humans in the operating theater. This paper presents analysis quantifying the payload reduction achieved by the new modular design as it pertains to extended missions to extreme environments. In addition to assisting surgeons, this system will take approximately 25% less space than the current equivalent MIS tools

Extracting 3D parametric curves from 2D images of helical objects

Helical objects occur in medicine, biology, cosmetics, nanotechnology, and engineering. Extracting a 3D parametric curve from a 2D image of a helical object has many practical applications, in particular being able to extract metrics such as tortuosity, frequency, and pitch. We present a method that is able to straighten the image object and derive a robust 3D helical curve from peaks in the object boundary. The algorithm has a small number of stable parameters that require little tuning, and the curve is validated against both synthetic and real-world data. The results show that the extracted 3D curve comes within close Hausdorff distance to the ground truth, and has near identical tortuosity for helical objects with a circular profile. Parameter insensitivity and robustness against high levels of image noise are demonstrated thoroughly and quantitatively

Ureteral tunnel length versus ureteral orifice configuration in the determination of ureterovesical junction competence: A computer simulation model

Introduction The long-held belief that a ureteral re-implant tunnel should be five times the diameter of the ureter, as proposed by Paquin in 1959, ignores the effect of the orifice on the occurrence of reflux. In 1969, Lyon proposed that the shape of the ureteral orifice (UO) is more important than the intravesical tunnel. However, both theories missed quantitative evidence from principles of physics. The goal of the current study was to test Lyon’s theory through numerical models (i.e. to quantify the sensitivity of ureterovesical junction (UVJ) competence to intravesical tunnel length and to the UO). Materials and methods The closure of a three-dimensional spatial configuration of ureter, constrained within a bladder, was simulated. Two common UO shapes (i.e. golf type vs 2-mm volcano type (Summary Fig.)), and two different intravesical ureteral tunnel length/diameter ratios (3:1 and 5:1) were examined. The required closure pressures were then compared. Results The UO was a significant factor in determining closure pressure. Given the same intravesical ureteral tunnel length/ diameter ratio, the required closure pressure for the volcanic orifice was 78% less than that for the golf orifice. On the other hand, the intravesical ureteral tunnel length/diameter ratio had minimal effect on the required closure pressure. As the intravesical ureteral tunnel length/diameter ratio changed from3:1 to 5:1, the required closure pressure was reduced by less than 7%, regardless of the orifice shape. Conclusions The simulation results showed that UVJ competence was more sensitive to a 2-mm protrusion of the UO compared to an increase in the intravesical tunnel length from 3:1 to 5:1. This agrees with Lyon’s theory, and at the same time challenges Paquin’s 5:1 rule. Researchers could use this information to consider the UO configuration in further animal, human, computer or material models

Imaging the Developing Heart: Synchronized Timelapse Microscopy During Developmental Changes

How do you use imaging to analyse the development of the heart, which not only changes shape but also undergoes constant, high-speed, quasi-periodic changes? We have integrated ideas from prospective and retrospective optical gating to capture long-term, phase-locked developmental time-lapse videos. In this paper we demonstrate the success of this approach over a key developmental time period: heart looping, where large changes in heart shape prevent previous prospective gating approaches from capturing phase-locked videos. We use the comparison with other approaches to in vivo heart imaging to highlight the importance of collecting the most appropriate data for the biological question.Comment: Carl J. Nelson and Charlotte Buckley and John J. Mullins and Martin A. Denvir and Jonathan Taylor, "Imaging the Developing Heart: Synchronized Timelapse Microscopy During Developmental Changes", Proc. SPIE (10499), 10499-41 (2018). Copyright 2018 Society of Photo Optical Instrumentation Engineers (SPIE

Neuronal graphs: a graph theory primer for microscopic, functional networks of neurons recorded by Calcium imaging

Connected networks are a fundamental structure of neurobiology. Understanding these networks will help us elucidate the neural mechanisms of computation. Mathematically speaking these networks are 'graphs' - structures containing objects that are connected. In neuroscience, the objects could be regions of the brain, e.g. fMRI data, or be individual neurons, e.g. calcium imaging with fluorescence microscopy. The formal study of graphs, graph theory, can provide neuroscientists with a large bank of algorithms for exploring networks. Graph theory has already been applied in a variety of ways to fMRI data but, more recently, has begun to be applied at the scales of neurons, e.g. from functional calcium imaging. In this primer we explain the basics of graph theory and relate them to features of microscopic functional networks of neurons from calcium imaging - neuronal graphs. We explore recent examples of graph theory applied to calcium imaging and we highlight some areas where researchers new to the field could go awry

Optical air data systems and methods

Systems and methods for sensing air outside a moving aircraft are presented. In one embodiment, a system includes a laser for generating laser energy. The system also includes one or more transceivers for projecting the laser energy as laser radiation to the air. Subsequently, each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines one or more air parameters based on the scattered laser radiation. Such air parameters may include air speed, air pressure, air temperature and aircraft orientation angle, such as yaw, angle of attack and sideslip

Optical air data systems and methods

Systems and methods for sensing air outside a moving aircraft are presented. In one embodiment, a system includes a laser for generating laser energy. The system also includes one or more transceivers for projecting the laser energy as laser radiation to the air. Subsequently, each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines one or more air parameters based on the scattered laser radiation. Such air parameters may include air speed, air pressure, air temperature and aircraft orientation angle, such as yaw, angle of attack and sideslip