FMRI Simulator: Development and Applications

Functional Magnetic Resonance Imaging (FMRI) is a non-invasive method of imaging brain function in-vivo. However, images produced in FMRI experiment almost invariably contain imperfections, known as artifacts. These artifacts can result from, for example, rigid-body motion of the head, magnetic field inhomogeneities, chemical shift and eddy currents. To investigate these artifacts, with the eventual aim of minimising or removing them completely, a computational model of the FMR image acquisition process was built which can simulate all of the above mentioned artifacts. The simulator uses a geometric definition of the object (brain), Bloch equations (to model the behaviour of the magnetisation) and a model for the Blood Oxygen Level Dependent (BOLD) activations. Furthermore, it simulates rigid-body motion of the object by solving Bloch equations for an object moving continuously in time (as opposed to assuming movement only between the acquisition of consecutive images). This is a novel approach in the area of MRI computer simulations. With this approach it is possible, in a controlled and precise way, to simulate the full effects of various rigid-body motion artifacts in FMRI data (e.g. spin-history effects, B0-motion interaction and within-scan motion blurring) and therefore formulate and test algorithms for their reduction. This thesis presents the development of the model for the simulator, its numerical implementation and solutions for the computational issues, and the validation of the simulator by comparing its outputs with existing theoretical and experimental results. Finally, the simulator is applied in a number of diverse applications. These applications include: comparing different acquisition techniques for eddy-current compensation; reproducing and extending experiments in neuronal current imaging; quantifying the performance of motion correction software; quantitatively evaluating the impact of stimulus correlated motion artifacts; and investigating the performance of Independent Component Analysis (ICA) as a tool for quantifying motion-related artifacts

Co-Creating Reassurance Journey Maps to Foster Engagement in Remote Patient Monitoring for Post-Operative Cancer Care

Remote patient monitoring can significantly enhance post-operative home recovery for cancer patients, yet its effectiveness is often hindered by low patient engagement. Reassurance has been identified as a key factor in improving engagement. Our study explored how cancer patients seek reassurance through a Patient Public Involvement workshop with former patients. This involved developing personas for participants to navigate reassurance scenarios and share their post-operative experiences. Based on this, we co-created a reassurance journey map to illustrate when reassurance is needed, the behaviours patients use to seek it, and how it can be effectively provided. Our findings highlight three key design principles: the limitations of digital technology in offering reassurance, the personalised nature of reassurance, and the need for holistic integration. These are intended to inform the design of reassurance-focused RPM systems that better support cancer patients during home recovery. Practical design recommendations are also provided for developers and clinicians

Tensile properties and fracture mechanism of IN-100 superalloy in high temperature range

Tensile properties and fracture mechanism of a polycrystalline IN-100 superalloy have been investigated in the range from room temperature to 900 °C. Optical microscopy (OM) and transmission electron microscopy (TEM) applying replica technique were used for microstructural investigation, whereas scanning electron microscopy (SEM) was utilized for fracture study. High temperature tensile tests were carried out in vacuumed chamber. Results show that strength increases up to 700 °C, and then sharply decreases with further increase in temperature. Elongation increases very slowly (6-7.5%) till 500 °C, then decreases to 4.5% at 900 °C. Change in elongation may be ascribed to a change of fracture mechanism. Appearance of a great number of microvoids prevails up to 500 °C resulting in a slow increase of elongation, whereas above this temperature elongation decrease is correlated with intergranular crystallographic fracture and fracture of carbides

Mycoremediation as Innovation Model of Ecoremediation of Highly Contaminated Soils

Mikoremedijacija je oblik bioremedijacije koji pomoću gljiva vrši detoksikaciju zagađenih zemljišta i voda. Gljive igraju važnu ulogu u svim ekosistemima i u stanju su da regulišu protok hranljivih materija i energije. Jedna od osnovnih uloga gljiva u ekosistemu je razgradnja koju vrše micelijumi. Micelijumi izlučuju vanćelijske enzime i kiseline koje razgrađuju lignin i celulozu. To su organska jedinjena iz lanca ugljenika i vodonika strukturom slična mnogim organskim zagađivačima. Na taj način razgrađuju lance toksina u jednostavnije i manje toksične hemikalije. Enzimi gljive mogu razložiti neke od najotpornijih materijala napravljenih od strane čoveka i prirode kao što su nafta, ulje, pesticidi, lijekovi, tekstilne boje itd. Neke od poznatih gljiva koje se koriste u mikoremedijaciji su: bukovača (Pleurotus ostreatus), ćuranov rep (Trametes versicolor), Shiitake gljive (Lentinus edodes), gljive bele truleži (Phanerochaete chrysosporium), Reishi gljive (Ganoderma lucidum), smrčak (Morchella Conica) itd. Najčešći metod mikoremedijacije je da se inokulišu drveni opiljci ili slama sa micelijumom gljive i stave na površinu kontaminiranog zemljišta ili tamo gde kontaminirana voda mora da proteče kroz to. U zavisnosti od nivoa zagađenja neophodno je izvršiti nekoliko uzastopnih primena da bi se toksini smanjili na prihvatljiv nivo. Micelije luče enzime koji usvajaju toksične materije sve dok se ne razviju u odrasle pečurke. Stoga je bitno zadržati miceliju da što duže raste prije nego se pretvori u oblik ploda. Prolećna inokulacija je bolja nego jesenja, jer micelije imaju više vremena da se rašire. Mnogi faktori utiču na brzinu i sposobnost apsorpcije i razgradnje toksina pomoću gljiva, a neki od njih su priroda ugljovodonika, temperatura, pH vrednost zemljišta, kiseonik, vlažnost vazduha i dr.Mycoremediation is the form of bioremediation which helps with fungi performing detoxification of contaminated soils and waters. Fungi play important role in all environments and are able to regulate the transfer of nutritious materials and energy. One of the basic roles of fungi in ecosystem is degradation which is performed by mycelia. Mycelia excrete extracellular enzymes and acids which break lignin and cellulose. Those are organic compounds from the chain of carbon and hydrogen similar by its structures to many organic pollutants. This way they break down toxins into simpler and less toxic chemicals. Fungi enzymes can break down some of the most resistant materials made by man and nature like crude oil, oil, pesticides, medicine, textile colors, etc. Some of know fungi which are used in mycoremediation are: Oysters (Pleurotus ostreatus), Turkey Tail (Trametes versicolor), Shittake mushrooms (Lentinus edodes), White-rot fungi (Phanerochaete chrysosporium), Reishi mushrooms (Ganoderma lucidum), Morel (Morchella Conica), etc. The most common method is to inoculate wood chips or straw with your mycoremediators and put that substrate on top of the problem soil or where the contaminated water has to flow through it. Depending on the level of contamination it is necessary to execute several consecutive applications in order for toxins to be reduced to acceptable level. Mycelia secrete enzymes which absorb toxic material all the time until they develop to grown mushrooms. Therefore, it is important to keep mycelia to grow as long as possible before it transforms in a form of fruit. Spring inoculations work better than fall inoculations as the mycelium has more time to grow- out. Many factors affect the speed and capability of absorption and degradation of toxins using fungi, and some of them are the nature of hydrocarbons, temperature, PH value of the soil, oxygen, humidity of air and similar

Održivo upravljanje otpadom u lokalnim samoupravama i zaštićenim područjima u Republici Srbiji

Moderni način života i težnja ka što bržem tehnološkom razvoju stvaraju sve veće probleme vezane za količine i menadžment generisanim otpadom. Upravljanje otpadom predstavlja složeni proces usled konstantne opasnosti po životnu sredinu kroz zagađenje vazduha, vode i zemljišta, kao i zdravlje ljudi. Nedostatak informacija o količinama, sastavu i mestu nastajanja otpada otežava proces deponovanja i kategorizacije, kao i njegovu reciklažu ili ponovnu upotrebu. Industrijalizacijom i razvojem modernog društva i neracionalnim korišćenjem prirodnih resursa povećava se količina otpada, te se javlja i potreba za organizovanim pristupom ovom problemu. Za rešavanje ovih pitanja, između ostalog, neophodni su konstantan monitoring, sprovođenje zakonske regulative i povećanje javne svesti. Ovo se posebno odnosi na prikupljanje pouzdanih podataka o količinama generisanog otpada, te njegovom zbrinjavanju u okviru lokalnih samouprava i zaštićenih područja. U Republici Srbiji za sada ne postoji sistemski organizovano upravljanje otpadom. Međutim, postoji dugoročna strategija u oblasti zaštite životne sredine koja podrazumeva poboljšanje kvaliteta života stanovništva i očuvanje prirode, gde važno mesto zauzima i pravilno postupanje sa otpadom.The modern way of life and aspiration for faster technological development creates increasing problems related to waste quantities and management. Waste management is a complex process due to the constant danger to the environment through pollution of air, water and soil as well as the human health. Lack of waste quantity, composition and location informations makes disposal and categorization process more difficult, as well as its recycling or reuse. Industrialization and development of modern society and irrational usage of natural resources increases the amount of waste, which creates the need for an organized approach to this problem. In order to resolve these issues, among other, the constant monitoring, implementation of legislation and increasing public awareness are necessary. This particularly refers to the collection of reliable data on the quantities of generated waste, and its disposal within the local communities and protected areas. There is no systemic organized waste management in the Republic of Serbia for the time being. However, there is the long-term strategy in the field of environmental protection, which implies improving the population quality of life and preserving the nature, where an important place has the proper waste treatment

Axon radius estimation with Oscillating Gradient Spin Echo (OGSE) diffusion MRI

The estimation of axon radius provides insights into brain function [1] and could provide progression and classification biomarkers for a number of white matter diseases [2-4]. A recent in silico study [5] has shown that optimised gradient waveforms (GEN) and oscillating gradient waveform spin echo (OGSE) have increased sensitivity to small axon radius compared to pulsed gradient spin echo (PGSE) diffusion MR sequences. In a follow-up study [6], experiments with glass capillaries show the practical feasibility of GEN sequences and verify improved pore-size estimates. Here, we compare PGSE with sine, sine with arbitrary phase, and square wave OGSE (SNOGSE, SPOGSE, SWOGSE, respectively) for axon radius mapping in the corpus callosum of a rat, ex-vivo. Our results suggest improvements in pore size estimates from OGSE over PGSE, with greatest improvement from SWOGSE, supporting theoretical results from [5] and other studies [7-9]

Axon radius estimation with Oscillating Gradient Spin Echo (OGSE) diffusion MRI

The estimation of axon radius provides insights into brain function [1] and could provide progression and classification biomarkers for a number of white matter diseases [2-4]. A recent in silico study [5] has shown that optimised gradient waveforms (GEN) and oscillating gradient waveform spin echo (OGSE) have increased sensitivity to small axon radius compared to pulsed gradient spin echo (PGSE) diffusion MR sequences. In a follow-up study [6], experiments with glass capillaries show the practical feasibility of GEN sequences and verify improved pore-size estimates. Here, we compare PGSE with sine, sine with arbitrary phase, and square wave OGSE (SNOGSE, SPOGSE, SWOGSE, respectively) for axon radius mapping in the corpus callosum of a rat, ex-vivo. Our results suggest improvements in pore size estimates from OGSE over PGSE, with greatest improvement from SWOGSE, supporting theoretical results from [5] and other studies [7-9]

Oscillations in a maturation model of blood cell production.

We present a mathematical model of blood cell production which describes both the development of cells through the cell cycle, and the maturation of these cells as they differentiate to form the various mature blood cell types. The model differs from earlier similar ones by considering primitive stem cells as a separate population from the differentiating cells, and this formulation removes an apparent inconsistency in these earlier models. Three different controls are included in the model: proliferative control of stem cells, proliferative control of differentiating cells, and peripheral control of stem cell committal rate. It is shown that an increase in sensitivity of these controls can cause oscillations to occur through their interaction with time delays associated with proliferation and differentiation, respectively. We show that the characters of these oscillations are quite distinct and suggest that the model may explain an apparent superposition of fast and slow oscillations which can occur in cyclical neutropenia. © 2006 Society for Industrial and Applied Mathematics