Gordon Eric SartyUniversity of Saskatchewan | U of S · Psychology, Biomedical Engineering Physics
Gordon Eric Sarty
P.Eng., Ph.D.
About
119
Publications
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Introduction
Current project = Development of MRI for use in space and on the Moon using gradient-free technology. The technology includes TRASE and quantum materials.
Past projects = Observational and theoretical astrophysics of compact objects, binaries and black holes. Camera network for fireballs. Mathematical physiology, especially of ovaries. fMRI.
Publications
Publications (119)
Interprofessional collaboration (IPC) in stroke care is accepted as best practice and necessary given the multi-system challenges and array of professionals involved. Our two-part stroke team simulations offer an intentional interprofessional educational experience (IPE) embedded in pre-licensure occupational therapy, physical therapy, pharmacy, me...
Objective
The design of an MRI for use in space requires that the hardware be kept to an absolute minimum in terms of mass, complexity, and power. In addition, NASA requirements are that the external stray field needs to be less than 3.2 Gauss, 7 cm from the MRI enclosure.TheoryRF encoding designs with Halbach magnets offer the best chance of meeti...
Detectors based on an ensemble of nitrogen-vacancy (NV) centres in diamond are the latest addition to the list of magnetometers capable of detecting weak magnetic fields. Here, we report the design, construction, and testing of an NV magnetometer with a wide spatial area excitation and collection capability. The system was developed for the purpose...
Recently designed dipolar Halbach magnets used in portable MRI systems are much lighter and more compact than standard permanent or superconductive magnets. However, improved designs and manufacturing techniques aiming at lower weight and smaller external size are an area of continual interest especially for application to space flight. Most Halbac...
TRansmit Array Spatial Encoding (TRASE) Magnetic Resonance Imaging (MRI) encodes image information in the Nuclear Magnetic Resonance (NMR) signal using spatially varying phases in a multiple spin-echo radio frequency (RF) pulse sequence. When the TRASE transmit coils are perfect, the spatial isophase RF contours produced are straight and orthogonal...
Transmit Array Spatial Encoding (TRASE) is a novel MRI technique that encodes spatial information by introducing phase gradients in the transmit RF (B1) magnetic field. Since TRASE relies on the use of multiple RF fields (B1 fields with different phase gradients) for k-space traversal, a TRASE pulse sequence requires RF pulses that are produced by...
MRI is desired for monitoring bone and muscle deterioration in astronauts during long-term spaceflights and on the International Space Station (ISS). However, the magnet is generally too heavy to be transported to the ISS. Therefore, we designed a light (~ 10 kg) magnet that allows transmit array spatial encoding (TRASE) MRI of the ankle on the ISS...
Optical centres embedded via nitrogen doping in polycrystalline diamonds (PCDs) are becoming increasingly useful for several wide-area applications including magnetic field sensing. Therefore, investigating the effect of step-wise surface nitrogen doping in PCDs deposited at low pressure is essential. In this study, the influence of a step-wise sur...
Introduction
Professional behaviour is regarded as an important competency for occupational therapy practice, yet little guidance exists for indicators underpinning development or remediation in the educational or practice settings. This study sought to confirm the content validity of observable professional behaviour indicators from an existing ev...
Nitrogen-vacancy (NV) centres in diamonds are emerging quantum materials having applications in quantum computing and magnetic field sensing. The ability to synthesize polycrystalline diamond films from chemical vapour deposition technique offers a possibility to grow cheap diamonds with NV centres over large areas. Till date, extensive studies hav...
Transmit Array Spatial Encoding (TRASE) is an MRI technique that uses radio-frequency (RF) magnetic field (B1) phase gradients for spatial encoding. A TRASE pulse sequence consists of a long echo train in which each echo samples a different k-space point. Due to the need for accurate refocusing, TRASE imaging performance depends on |B1| homogeneity...
Nitrogen-vacancy (NV) centres in diamonds are emerging as spin-sensors of immense interest with applications in physics and the life sciences. The ability to synthesize polycrystalline diamond films from a chemical vapour deposition (CVD) technique on a silicon substrate offers the possibility to grow cheap diamonds with NV centres over large areas...
The last few decades have seen a growing interest in the study of nitrogen-vacancy (NV) centres in diamonds because of the large number of potential applications. Of those numerous applications, the NV centre can act as a sensor that has the ability to detect weak magnetic fields with high signal-to-noise (SNR). Recently, Sarty et al. developed a r...
While the idea of using spatial encoding fields (SEM) for image formation has been proven, conventional wisdom still holds that a magnetic resonance imaging (MRI) system begins with a highly uniform magnetic field. In particular, radio frequency (RF) encoding MRIs designed and tested to date have largely used uniform magnetic fields. Here we demons...
Objectives:
Major depression in the context of chronic pain has been conceptualized implicitly as a latent variable, in which symptoms are viewed as manifestations of an underlying disorder. A network approach provides an alternative model and posits that symptoms are causally connected, rather than merely correlated, and that disorders exist as s...
Interprofessional practice (IPP) is the accepted standard of care for clients following a stroke. A brief, embedded and evidence-based IPP team simulation was designed to address stroke care knowledge and IPP competencies for students within limited curriculum space. Each team was required to construct a collaborative care plan for their patient du...
Background:
In B1 encoded MRI, a realistic non-linear phase RF encoding coil will generate an inhomogeneous B1 field that leads to spatially dependent flip angles. The non-linearity of the B1 phase gradient can be compensated for in the reconstruction, but B1 inhomogeneity remains a problem. The effect of B1 inhomogeneity on tip angles for convent...
RF phase encoded MRI uses spatial RF phase gradients in place of B0 gradients coils to encode information. Using a nonlinear RF phase gradient coil instead of linear one leads to a larger field of view. However, this coil will generate an in-homogeneous B1 field which result in pulse imperfection. To minimize the effect of pulse imperfection, the a...
Portable MRI can be possible by eliminating gradient coils and B0 homogeneity requirements. Relaxing the B0 homogeneity requirements leads to non-uniform B0 field. In-homogeneous B0 fields have the potential to encode spatial information in one direction for use in novel image encoding schemes. We investigated the possibility of image reconstructio...
Diffusion-weighted imaging (DWI) is based on the detection of water molecule movement in interstitial and intracellular space, and that motion may be restricted in ischemia and in tumors. An early diagnosis and
characterization of several cancer related diseases is possible with DWI. Diffusion-weighted images are therefore important for patient ma...
Introduction: Conventional Magnetic Resonance Imagers (MRI) use a uniform main magnetic field (B 0) to polarize the sample being imaged. Non-homogeneity in the B 0 field leads to image distortion. In practice it is impossible to have a perfectly homogeneous B 0 field so shim coils are used to remove the inhomogeneity of the field. However, shim coi...
Purpose: The TRansmit Array Spatial Encoding (TRASE) method encodes spatial information through the use of spatially varying B 1 transmit phase fields instead of using traditional B 0 gradient coil systems [1]. An ideal TRASE coil array creates B 1 fields with linearly-varying spatial phases. The imaging data generated with an ideal array may be re...
The present study is a cluster analytic examination and validation of psychopathic offender subtypes from 4 combined samples of Canadian federally incarcerated offenders, most of whom were serving sentences for violent offenses. The men were rated on the Hare Psychopathy Checklist-Revised (PCL-R; Hare, 1991, 2003) on the basis of comprehensive file...
Progress in the development of portable MRI hinges on the ability to use lightweight mag- nets that have non-uniform magnetic fields. An image encoding method and mathematical procedure for recovering the image from the NMR signal from non-uniform magnets with closed isomagnetic contours is given. Individual frequencies in an NMR signal from an obj...
A wrist-sized Magnetic Resonance Imager (MRI) has been designed for installation on the International Space Station (ISS) in 2016. The ISS-MRI will be housed in an double EXPRESS rack in an ISS standard International Standard Payload Rack (ISPR). The design mass of the complete ISS-MRI is less than 50 kg. The ISS-MRI uses new approaches to MRI magn...
Dwarf galaxies and globular clusters may contain intermediate mass black
holes ($10^{3}$ to $10^{5}$ solar masses) in their cores. Estimates of
~$10^{3}$ neutron stars in the central parsec of the Galaxy and similar numbers
in small elliptical galaxies and globular clusters along with an estimated high
probability of ms-pulsar formation in those en...
The change and deterioration of an astronaut's physiology during long-term space flight remains a significant concern. A magnetic resonance imager (MRI), that is available during space flight, would be a valuable tool that can be used to understand more fully the altered physiological processes, and to find ways of ameliorating those changes. The f...
The theory of embodied cognition postulates that the brain represents semantic knowledge as a function of the interaction between the body and the environment. The goal of our research was to provide a neuroanatomical examination of embodied cognition using action-related pictures and words. We used functional magnetic resonance imaging (fMRI) to e...
The management of weightlessness-induced musculoskeletal deterioration, along with other medical issues, in astronauts on long-term space flights remains a primary problem to be solved before interplanetary travel becomes feasible. Finding ways to prevent or reduce these medical sequelae to acceptable levels by exercise and (or) pharmacological int...
Some researchers have argued in favour of verbs primarily activating the left frontal operculum (FO) in the dorsal stream, and left middle temporal (MT) region in the ventral stream, and that nouns primarily activate the left inferior temporal (IT) region in the ventral stream. Others have suggested that the activation representing noun and verb pr...
A complete understanding of the pathophysiological changes that occur during long-duration spaceflight, and of the countermeasures needed to ameliorate their effects, remains elusive. A primary reason for that lack of basic knowledge is the very limited amount of in-flight physiological data available. The ability to image astronauts frequently wit...
We present the results of space-based photometric and ground-based
spectroscopic observing campaigns on the gamma-ray binary LS 5039. The new
orbital and physical parameters of the system are similar to former results,
except we found a lower eccentricity. Our MOST-data show that any broad-band
optical photometric variability at the orbital period...
The purpose of this study was to assess cortical activation associated with the cross-education effect to an immobilized limb, using functional magnetic resonance imaging.
Fourteen right-handed participants were assigned to two groups. One group (n = 7) wore a cast and strength trained the free arm (CAST-TRAIN). The second group (n = 7) wore a cast...
Building on the currently active program of observing High Mass X-ray
Binaries (HMXBs), we describe here a challenging extension of the
project for experienced AAVSO observers who want to push their observing
to the limit. A new subclass of HMXBs, the Supergiant Fast X-ray
Transients (SFXTs), have been recently discovered in INTEGRAL data and
are s...
CBET 2729 available at Central Bureau for Astronomical Telegrams.
CBET 2728 available at Central Bureau for Astronomical Telegrams.
Hierarchical triple systems comprise a close binary and a more distant component. They are important for testing theories of star formation and of stellar evolution in the presence of nearby companions. We obtained 218 days of Kepler photometry of HD 181068 (magnitude of 7.1), supplemented by ground-based spectroscopy and interferometry, which show...
Received [year] [month] [day]; accepted [year] [month] [day] Abstract We searched for long period variation in V -band, I C -band and RXTE X-ray light curves of the High Mass X-ray Binaries (HMXBs) LS 1698 / RX J1037.5−5647, HD 110432 / 1H 1249−637 and HD 161103 / RX J1744.7−2713 in an attempt to discover orbitally induced variation. Data were obta...
CBET 2684 available at Central Bureau for Astronomical Telegrams.
The scientific investigation of Nature relies on mathematics. While mathematics itself is precise, its application to the understanding of nature always involves an approximation. The approximate nature of mathematical application ultimately limits the scientific approach to Nature, but the freedom to make appropriate approximations allows us to un...
The Canadian Astronomical Society (CASCA) has a very active Education and Public Outreach (EPO) Committee that promotes and supports astronomy education and outreach across Canada. The Committee submitted a White Paper to Canada's Long Range Planning Panel in 2010 outlining the goals of Canadian astronomy EPO for the next 10 years. This poster will...
A long‐term observing project to determine unknown orbital periods in High Mass X‐ray Binaries (HMXB) has been underway since 2005. The primary search methods are to look for periodicities in optical light curves and in spectroscopically
measured
radial velocities. In the course of our searches, other non‐orbital periodicities and variations were...
The results of a coordinated space-based photometric and ground-based spectroscopic observing campaign on the enigmatic gamma-ray binary LS 5039 are reported. Sixteen days of observations from the MOST satellite have been combined with high-resolution optical echelle spectroscopy from the 2.3m ANU Telescope in Siding Spring, Australia. These observ...
The aim of this work is to combine behavioural and functional magnetic resonance imaging (fMRI) data to advance our knowledge of where the Frequency x Regularity interaction on word naming is located in the cerebral cortex. Participants named high and low frequency, regular and exception words in a behavioural lab (Experiment 1) and during an fMRI...
LS 5039 is a relatively close microquasar consisting of a late O-type star and a compact object (very possibly a black hole) on a highly eccentric orbit with a period of 3.9 days. The high X-ray, gamma-ray and radio luminosity indicate light-matter interaction, which arise from the stellar wind of the primary star accreting toward the black hole. F...
IAUC 9093 available at Central Bureau for Astronomical Telegrams.
A bright fireball was widely observed across Alberta, Saskatchewan,
Manitoba, and Montana during late twilight on November 20, 2008. The
fireball and subsequent dust trail, or shadows cast by the fireball,
were widely recorded. The meteoroid had a below average initial velocity
and sufficient data exist to constrain the orbit. The fireball
fragment...
The direct observation of clumpy circumstellar material in high mass X-ray binaries (HMXBs) is proposed. We propose to observe the two HMXBs V420 Aur and LS 5039, based on our optical data obtained over the past four years. With precision time- series photometry from the post-cryo IRAC instrument we expect the following scientific return: (i) Chara...
A bright fireball was widely observed across Alberta, Saskatchewan and Manitoba from 17:26:40 to 17:26:45 MST during late twilight on November 20, 2008.
The high-mass X-ray binary RX J0146.9+6121, with optical counterpart LS I+61°235 (V831 Cas), is an intriguing system on the
outskirts of the open cluster NGC 663. It contains the slowest Be type X-ray pulsar known with a pulse period of around 1400
s and, primarily from the study of variation in the emission line profile of Hα, it is known to have...
We report on post X-ray outburst (ATEL #1792) observations of the transient pulsar and Be/X-ray binary V0332+53 (BQ Cam). We obtained an optical spectrum (range 4700-7000 Angstroms, resolution 3 Angstroms) on October 22.54 UT using the 1.82-m Plaskett Telescope of the National Research Council of Canada. The spectrum shows a strong (FWHM 12 Angstro...
The objective of this investigation was to examine the cognitive characteristics of individuals who demonstrate successful and unsuccessful self-regulation of physical activity behavior. In Study 1, participants articulated 1-week intentions for physical activity and wore a triaxial accelerometer over the subsequent 7 days. Among those who were mot...
The temperatures of electrons and ions in the post-shock accretion region of a magnetic cataclysmic variable (mCV) will be equal at sufficiently high mass flow rates or for sufficiently weak magnetic fields. At lower mass flow rates or in stronger magnetic fields, efficient cyclotron cooling will cool the electrons faster than the electrons can coo...
We examined the correlation between behavioural reaction time and functional imaging parameters of the blood oxygenated level dependent (BOLD) response in Broca's Area during a word identification task, and whether the correlation [Magnetic Resonance Imaging 22 (2004) 451-455] varies as a function of four stimulus types: regular words (REGs) (e.g.,...
Previous neuroanatomical research has shown that semantic processing of action-related language activates the premotor, motor, and sensory cortices somatotopically (e.g., Tettamanti et al., J Cognitive Neurosci. 2005;17(2): 273-281, using a listening task, and Hauk et al., Neuron. 2004;41:301-307 and Pulvermuller et al., Eur J Neurosci 2005;21:793-...
The blood oxygen level-dependent (BOLD) fMRI signal does not measure neuronal activity directly. This fact is a key concern for interpreting functional imaging data based on BOLD. Mathematical models describing the path from neural activity to the BOLD response allow us to numerically solve the inverse problem of estimating the timing and amplitude...
Cross-education of strength is the increase in strength of the untrained contralateral limb after unilateral training of the opposite homologous limb. We investigated central and peripheral neural adaptations associated with cross-education of strength. Twenty-three right-handed females were randomized into a unilateral training group or an imagery...
The problem of evaluating an averaged functional magnetic resonance imaging (fMRI) response for repeated block design experiments was considered within a semiparametric regression model with autocorrelated residuals. We applied functional data analysis (FDA) techniques that use a least-squares fitting of B-spline expansions with Tikhonov regulariza...
We demonstrate, and show how to eliminate, a task-correlated breathing activation artefact created while performing exercise tasks during a gap in functional magnetic resonance imaging (fMRI).
Two studies are presented. The first was intended to isolate a reliable fMRI paradigm for intense handgrip contractions. A gapped acquisition was used to red...
This is a call for amateur astronomers who have the equipment and experience for producing high quality photometry to contribute to a program of finding periods in the optical light curves of high mass X-ray binaries (HMXB). HMXBs are binary stars in which the lighter star is a neutron star or a black hole and the more massive star is an O type sup...
There have been several studies supporting the notion of a ventral-dorsal distinction in the primate cortex for visual object processing, whereby the ventral stream specializes in object identification, and the dorsal stream is engaged during object localization and interaction. There is also a growing body of evidence supporting a ventral stream t...
The ratios of hydrogen Balmer emission line intensities in cataclysmic variables are signatures of the physical processes that produce them. To quantify those signatures relative to classifications of cataclysmic variable types, we applied the multivariate statistical analysis methods of principal components analysis and discriminant function analy...
Most current models of the neurophysiology of basic reading processes agree on a system involving two cortical streams: a ventral stream (occipital-temporal) used when accessing familiar words encoded in lexical memory, and a dorsal stream (occipital-parietal-frontal) used when phonetically decoding words (i.e., mapping sublexical spelling onto sou...
fMRI is a very popular method for researchers and clinicians to image human brain activity in response to given mental tasks. This book presents a comprehensive review of the methods for computing activity maps, while providing an intuitive and mathematical outline of how each method works. The approaches include statistical parametric maps (SPM),...
The objective of the study was to determine if nuclear magnetic resonance (NMR) spectral features of ovarian follicular fluid were correlated with the physiological status of follicles so that we could assess the feasibility of using NMR spectroscopy during assisted reproduction therapy. Thirty-five sexually mature, nullparious heifers were monitor...
Introduction. A mathematical model of ovarian follicular growth is applied to the problem of predicting ovarian response in a superstimulation protocol. Methods. Fifty-four women enrolled in an ovarian superstimulation program of therapy for the amelioration of idiopathic infertility had their ovarian cycles synchronized by taking Demulen 30 for tw...
To implement and evaluate a multiple-process functional magnetic resonance imaging (fMRI) paradigm designed to effectively and efficiently activate several language-related regions for use with neurosurgical patients. Both overt and covert response conditions were examined.
The fMRI experiments compared the traditional silent word-generation condit...
The temporal magnetic resonance (MR) appearance of human brain tissue during formalin fixation was measured and modeled using a diffusion mathematical model of formalin fixation. Coronal MR images of three human brains before formalin fixation and at multiple time points thereafter were acquired. T1 relaxation, T2 relaxation, water apparent diffusi...
To evaluate different imaging protocols, especially with respect to radio frequency (RF) receiver coil location, for their suitability in providing least squares derived quantitative T2 values of ovarian follicular fluid for investigations of basic ovarian physiology.
The ovaries of 10 women were imaged via magnetic resonance imaging (MRI) using ex...
Online MRI software for clinical functional magnetic resonance imaging (fMRI) testing is currently limited to a simple t-test method. Here we evaluate a repeated block design general linear model (GLM) method of analysis, BOLDfold, that is simple and robust enough to be used directly on a clinical MRI without the need for off-line processing. Six s...
Research on the modularity of perceptual and cognitive processes has often pointed to a ventral-dorsal distinction in cortical pathways that depend upon the nature of the stimuli and the task. However, it is not clear whether the dorsal, occipital-parietal stream specializes in locating visual objects (i.e., a "where" stream), or taking action towa...
We present time-series observations, spectra and archival outburst data of a newly-discovered variable star in Hercules, Var Her 04. Its orbital period, mass ratio, and outburst amplitude resemble those of the UGWZ-type subclass of UGSU dwarf novae. However, its supercycle and outburst light curve defy classification as a clear UGWZ. Var Her 04 is...
Previous functional magnetic resonance imaging (fMRI) studies have investigated the role of phonological processing by utilizing nonword rhyming decision tasks (e.g., Pugh et al., 1996). Although such tasks clearly engage phonological components of visual word recognition, it is clear that decision tasks are more cognitively involved than the simpl...
The objective of the study was to determine the feasibility of using apparent diffusion coefficient (ADC) measurement for the differential diagnosis of malignancy in ovarian masses.
Twelve cases involving ovarian masses were imaged using spin echo diffusion magnetic resonance imaging (MRI). Five cases involved malignant ovarian masses, on the basis...
The number of MRI applications that use radial k-space data acquisition have been increasing because of their inherent robustness to motion-induced reconstruction image artifacts relative to Cartesian acquisition methods. However, images reconstructed from radial data are more prone to image degrading effects due to magnetic field inhomogeneities t...