Laurentian University
  • Greater Sudbury, Canada
Recent publications
Enzymatic degradation of elastin by matrix metalloproteinases (MMPs) leads to the permanent dilation of aortic wall and constitutes the most prominent characters of aortic aneurysm and aging-related medial degeneration. Hydrogen sulfide (H2S) as a gasotransmitter exhibits a wide variety of cardio-protective functions through its anti-inflammatory and anti-oxidative actions. Cystathionine gamma-lyase (CSE) is a main H2S-generating enzyme in cardiovascular system. The regulatory roles of CSE/H2S system on elastin homeostasis and blood vessel degeneration have not yet been explored. Here we found that aged CSE knockout mice had severe aortic dilation and elastic degradation in abdominal aorta and were more sensitive to angiotensin II-induced aortic elastolysis and medial degeneration. Administration of NaHS would protect the mice from angiotensin II-induced inflammation, gelatinolytic activity, elastin fragmentation, and aortic dilation. In addition, human aortic aneurysm samples had higher inflammatory infiltration and lower expression of CSE. In cultured smooth muscle cells (SMCs), TNFα-induced MMP2/9 hyperactivity and elastolysis could be attenuated by exogenously applied NaHS or CSE overexpression while further deteriorated by complete knockout of CSE. It was further found that H2S inhibited MMP2 transcription by posttranslational modification of Sp1 via S-sulfhydration. H2S also directly suppressed MMP hyperactivity by S-sulfhydrating the cysteine switch motif. Taken together, this study revealed the involvement of CSE/H2S system in the pathogenesis of aortic elastolysis and medial degeneration by maintaining the inactive form of MMPs, suggesting that CSE/H2S system can be a target for the prevention of age-related medial degeneration and treatment of aortic aneurysm.
Plain Language Summary The western Athabasca Basin, straddling the border of Saskatchewan and Alberta in Canada, is home to some of the highest‐grade, large tonnage uranium deposits in the world. Recent studies have suggested a spatial connection between uranium ore systems that are found near the earth’s surface and geological processes occurring deep within the crust. However, the processes connecting the lower crust to these shallow deposits is poorly understood. This study used 3D models created from magnetotelluric data, a passive a geophysical technique that measures the earth’s natural electric and magnetic fields, to image the earth from surface to a depth of 40 km. We identified a voluminous igneous intrusion that extends from the surface to great depths in the earth’s crust. We propose that this intrusion may have contributed to the uranium endowment of the basin, and that radiogenic heat from the large igneous body helped circulate uranium‐bearing fluids through the shallow crust along reactivated geologic structures. The modeling, when combined with other geoscientific datasets, showcases the role of high‐heat producing granitic intrusions in driving the hydrothermal fluid cells that formed the deposits.
This study addresses marine palaeoredox conditions of the mid-Neoproterozoic by analysing the Mo isotope, trace element, and U-Th-Pb isotope compositions of shallow water microbial carbonate, deep water pelagic carbonate, and shale from the Stone Knife Formation (SKF) in NW Canada. The U-Th-Pb isotope SKF systematics of reef microbialite carbonates, and the moderately expressed negative Ce anomalies are consistent with the presence of dissolved O2 in the surface waters. Thirteen of 14 analysed samples yield a depositional ²⁰⁶Pb/²³⁸U regression age of 0.850 ± 0.028 Ga. The Mo isotope data (δ⁹⁸Mo) are distinct for the microbial and pelagic carbonates and the deeper water shales, with the isotopically heaviest black shales 0.4 ‰ lighter than the heaviest carbonate. The bulk digestion carbonate δ⁹⁸Mo data scatter widely, ranging up to 1.64 ‰, and are not reproducible between repeat digestions. The spread in shallow-water carbonate δ⁹⁸Mo cannot be attributed to a single origin (e.g., admixture of silicate-hosted Mo) and probably reflects a combination of factors, including the complex pathway of Mo into microbial carbonates. Regardless, we propose a minimum δ⁹⁸Mo of 1.64 ‰ for the 0.85 Ga ocean, similar to other Neo- and Mesoproterozoic estimates from studies of proxies other than black shale. Our new black shale δ⁹⁸Mo data agree with most previous results from 1.8 to 0.7 Ga shales. If interpreted as reflecting seawater, this would mean a minimum oceanic δ⁹⁸Mo composition of only 1.29 ‰, implying a limited oxic reservoir compared to the modern Mo budget in agreement with previous studies. This study’s results suggest that the discrepancy could also be explained by a systematic offset between δ⁹⁸Mo compositions of black shales and the overlying water columns, regardless of depositional environment, akin to the relative depth distribution of δ⁹⁸Mo in modern euxinic water columns such as the Black Sea. If valid, an implied heavier seawater δ⁹⁸Mo throughout the Proterozoic would indicate that the magnitude of the Mo oxic sink remained relatively stable throughout the Proterozoic, shifting the apparent expansion of oxygen towards the younger boundary of the interpreted onset of the NOE (ca. 1.0–0.54 Ga).
BACKGROUND: There is a dearth of research about occupational health and safety experience in Indigenous communities and compensation applications from Indigenous workers appear limited. OBJECTIVE: This qualitative descriptive study was designed to explore workers’ compensation experiences in some Canadian Indigenous communities. METHODS: A community-based participatory research approach was used to conduct focus groups (n = 25 participants) in three Northeastern Ontario (NEO) Indigenous communities and at one NEO Indigenous employment centre. Semi-structured focus group questions addressed community experience with workers’ compensation, the compensation process, and discussion of a training session about the process. Reflexive thematic analysis followed Braun and Clarke procedures. RESULTS: Discussion with study participants resulted in these themes: 1) both lack of knowledge, and knowledge, about compensation demonstrated, 2) impact of lack of compensation coverage and need for universal coverage on reserve, 3) need for community training sessions about workers compensation, 4) workload and financial impact of workers’ compensation on reserve, and 5) requirement for cultural competence training in the compensation board. CONCLUSIONS: This qualitative descriptive study revealed the: need for more information about applying for workers’ compensation and navigating the process, need for universal workplace insurance coverage in Indigenous communities, demand for community-based compensation process training, community costs of compensation, and the requirement for cultural safety and competence training for compensation organization employees. More education about the workers’ compensation process would be of benefit to leadership, health care providers, administrative personnel, employers, and employees on reserves. Nurses in community health centres are well situated to provide further guidance.
High critical temperature cuprate superconducting materials are composed of copper oxide layers and interlayer charge reservoirs. When not doped, these cuprates behave as antiferromagnetic Mott insulators. We propose to design new materials by combining alternating layers of parents of hole-doped and electron-doped cuprates and modifications thereof. The idea behind this combination is to frustrate antiferromagnetism near half-filing. Our goal is to find an undoped cuprate that can be a quantum metal, which means a metal characterized by long-range antiferromagnetic order or only strong antiferromagnetic correlations, i.e., it could thus be a stable ground state against other perturbations. However, the new metallic states sought here could be precursors to new superconducting states in the absence or presence of doping. Using the density functional theory, we report on two hypothetical compounds, {La}{Pr}CuO4 and {La}{V}CuO4, that illustrate the different physics described above. The curly brackets mean that the preparation of these compounds shall be done by depositing a layer containing Pr, then one CuO2 layer, then finally the La layer in {La}{Pr}CuO4 for example. We examined the configurations formed by the positions of the charge reservoir‘s atoms with respect to the CuO2 layer in the new procedure we propose here. This paper reports on the X-ray diffraction, electronic, optical, and magnetic properties of these hypothetical materials. We found that {La}{Pr}CuO4 is a Mott insulator, but {La}{V}CuO4 is an undoped correlated quantum metal with long-range antiferromagnetic order. These two compounds illustrate well the transition from a Mott insulator to a quantum metal.
The miniaturization of components in mechanical and electronic equipment has been the driving force for the fast development of micro/nanosystems [...].
Fetal programming is the concept that maternal stressors during critical periods of fetal development can alter offspring phenotypes postnatally. Excess glucocorticoids can interact with the fetus to effect genetic and epigenetic changes implicated in adverse developmental outcomes. The present study investigates how chronic exposure to the synthetic glucocorticoid dexamethasone during late gestation alters the expression of genes related to behavior in brain areas relevant to the regulation and function of the hypothalamic–pituitary–adrenal axis. Pregnant Wistar Kyoto rats received subcutaneous injections of dexamethasone (100 μg/kg) daily from gestational day 15–21 or vehicle only as sham controls. The amygdala and paraventricular nucleus (PVN) were micro-punched to extract mRNA for reverse transcription and quantitative polymerase chain reaction for the analysis of the expression of specific genes. In the PVN, the expression of the glucocorticoid receptor NR3C1 was downregulated in female rats in response to programming. The expression of CACNA1C encoding the Cav1.2 pore subunit of L-type voltage-gated calcium channels was downregulated in male and female rats prenatally exposed to dexamethasone. Collectively, the results suggest that prenatal exposure to elevated levels of glucocorticoids plays a role in the dysregulation of the hypothalamic–pituitary–adrenal axis and potentially learning and memory by altering the expression of specific genes within the amygdala and PVN.
Objectives The overall objective of this proposed project is to examine the impact of the COVID-19 pandemic on the mental health, functioning and wellbeing of medical laboratory technologists (MLT) and medical laboratory technicians/assistants (MLT/A) in Ontario, Canada. Methods A cross-sectional study included a self-reported questionnaire for MLT and MLT/A in Ontario. The questionnaire included questions about demographics and occupational characteristics. Questions about mental health, functioning, well-being and psychosocial work environments were also included using validated questionnaires. Results There were 551 MLT and 401 MLT/A in the analytic sample. Most of the respondents were women. The mean age and standard deviation of the overall sample were 42.0 ± 11.8. MLT demonstrated higher quantitative demands, possibilities for development, and organizational justice compared to MLT/A. The scores of work pace, emotional demands, role conflicts, job insecurity, insecurity over working conditions and negative acts were higher for MLT/A than MLT. The WHODAS 2.0 scores of the respondents were 20.80 ± 6.68, higher than approximately 92% average people. For both groups, most respondents scored the COPSOQ-III domains as worse since COVID-19. Conclusion The study provides preliminary evidence regarding the workplace mental health outcomes of medical laboratory professionals in Ontario, Canada. The findings suggest that MLT and MLT/A experience psychosocial work conditions that impact mental health, functioning and disability. Accordingly, additional research is necessary to understand the experiences of medical laboratory professionals.
Despite a well-developed structural framework, orogenic gold deposits from the Malartic-Val-d’Or Camp (MVC) report ages that span nearly 345 million years (~ 2705–2360 Ma), significantly post-dating the tectono-metamorphic history of the Abitibi-Wawa Orogeny, and are in conflict with the structural setting along the retrograde path of the orogenic cycle. Gold in the MVC is commonly associated with three events that form pre- and syn-/late-regional penetrative fabric (S2), developed during major N-S shortening (D2, ~ 2669–2643 Ma): (1) pre-D2 quartz-carbonate veins; (2) deformed quartz-carbonate stockworks, entrained in S2; (3) laminated brittle-ductile quartz-tourmaline-carbonate reverse-shear and tension veins, sub-parallel to S2, which contain the bulk of the gold. Here, we present in situ U–Pb geochronological and rare earth element (REE) data from 85 xenotime grains, hosted by quartz-carbonate veins (Kiena S50) and quartz-tourmaline-carbonate veins (Goldex, Triangle, Plug #4, Beaufor, Pascalis Gold Trend, and Akasaba West). Xenotime in textural equilibrium with Au-hosting pyrite of pre-D2 veins yields a subtle negative Eu anomaly and elevated medium-REE contents, and records an auriferous hydrothermal event at 2686 ± 15 Ma (n = 19; 11 grains; MSWD = 2.8), consistent with cross-cutting relationships with dated intrusions. Late-D2 veins record two subsequent hydrothermal events, based on texture and chemistry of xenotime. Xenotime in textural equilibrium with gold-bearing pyrite contains elevated medium-REE values (Nd>1000 ppm; Sm>2490 ppm) and constrains the timing of vein emplacement to 2643 ± 3 Ma (n = 92; 44 grains; MSWD = 1.2), dating the main phase of quartz-tourmaline-carbonate vein formation and major gold precipitation. Xenotime in textural disequilibrium with auriferous sulfides, located at dissolved sulfide grain boundaries and in sulfide fractures, contains lower medium-REE values (Nd<1000 ppm; Sm<2490 ppm), and yields an age of 2607 ± 5 Ma (n = 63; 30 grains; MSWD = 1.9), indicating a second period of gold mineralization. Our data imply that district-scale gold mineralization in the MVC formed during at least two short-lived hydrothermal periods with the bulk of orogenic gold introduced along the retrograde path of the orogenic cycle, ~25–30 million years post-peak metamorphism.
Bare and manganese dioxide coated ANSI-304 stainless steel anodes were evaluated for use in electrolytic cyanide waste effluent treatment using bicarbonate buffered electrolytes. Cyclic voltammetry of 10 mM carbonate pH 10 buffered electrolytes showed evidence of mass transfer limited cyanide oxidation just prior to the onset of oxygen gas evolution for both electrode types, and a reaction mechanism in which cyanide is oxidized via reaction with hydroxyl radical containing higher oxidation state species on electrode surfaces is proposed. The results of galvanostatic experiments, conducted in the same base electrolyte with addition of 250 mg L ⁻¹ cyanide at a current density of 2 mA cm ⁻² , were fit to a pseudo-first order model of mass transfer limited cyanide oxidation with little difference in cyanide oxidation performance between bare steel and the MnO 2 coated electrodes. However, addition of 10 mg L ⁻¹ of dissolved copper to the electrolyte was found to enhance the kinetics of cyanide oxidation when employing bare stainless steel electrodes, but had no appreciable effect on cyanide oxidation performance for cells employing manganese dioxide coated electrodes.
To systematically study the influence of loading environment system stiffness (LESS) on post-peak stress-strain curves and failure modes of brittle hard rocks, marble and granite specimens are tested under uniaxial compression under axial-straincontrolled loading using a brittle hard rock testing system named Stiffman with variable LESS. The test results show that the post-peak descending slopes of the stress-strain curves under low LESS are steep, and with the increase of the LESS, the slopes are gentle. In addition, as LESS increases, AE events in the post-peak deformation stage gradually transit from a concentrated distribution near the peak strength to a dispersed distribution in the whole post-peak deformation stage, and the maximum AE rate and the maximum cumulative AE count decrease approximately linearly with the increase of LESS. The number of splitting macrocracks and the degree of damage decrease as LESS increases, indicating that the post-peak failure process is more stable when LESS is high. The mechanism that leads to different post-peak descending slopes of stress-strain curves under different LESS is analyzed by comparing the variations of axial stress, axial and lateral strains, rates of axial and lateral strains over time in the loading process, and analyzing the relations between the maximum axial stress drop rate, the average axial strain rate amplitude, the maximum lateral strain rate and LESS. Fitting formulas relating LESS to the post-peak deformation modulus are established. Finally, pillar stability is discussed based on energy absorption and release considering the post-peak slopes of the pillar and surrounding rock. Considering the influence of LESS on the post-peak stress-strain curves of rocks, it is advisable to obtain strength and deformation properties of brittle rocks in line with the field LESS so as to provide more accurate parameters for rock engineering design and analysis.
We present an applied model that helps restoration practitioners select an ideal mix of species to plant in order to meet their restoration objectives. The model generates virtual plant communities designed to optimize the delivery of multiple ecosystem functions. We used an optimization approach to find the most cost-effective combinations of species to plant to optimize the delivery of four ecosystem functions: rapid establishment of vegetation cover, soil building, biological soil health and resistance to invasion. We used trait-function relationships to characterize species' effects on ecosystem functions. This model accounts for key operational constraints selected by the user, including budget, the number of species to plant, and which functions to consider. The user can also decide whether or not to maximize the functional diversity of the species mix to increase its resilience to global environmental change. To demonstrate the practicality of this approach, we derived optimal species mixtures for the restoration of forests damaged by Cu-Ni smelters in the City of Greater Sudbury (Ontario, Canada). The species mixtures generated by the model varied according to which functions and operational constraints were selected. Results show that the species mixtures that were the most effective at delivering multiple functions were also cost-effective, but were less functionally diverse. This tool provides restoration practitioners with cost-effective restoration strategies for managing the recovery of multi-faceted socio-economic and environmental values in disturbed landscapes.
The mechanical responses of tunnels are time-dependent due to creep deformation of rock masses, which can result in large deformations on tunnel walls over time and influence excavation stability. This study investigates time-dependent deformation behaviors of tunnels excavated in jointed rock masses. The creep deformations of both rock and joints are considered using a creep model for jointed rock masses implemented in a distinct-element method code. Simulations of the time-dependent deformation behavior of tunnels are conducted using two-dimensional plane strain models based on the convergence-confinement analysis method. The weakening of the rock mass in a cross-section in an excavated tunnel due to time-dependent deformation of rock mass is simulated using the internal pressure reduction method. Stand-up times of tunnels excavated in jointed rock masses with different rock mass qualities and unsupported roof spans are simulated. The simulation results agree with field data, which validates the effectiveness of the analysis approach used. The analysis approach provides a useful tool for improving the understanding of time-dependent deformation behavior of tunnels.
In this article, we consider flat and curved Riemannian symmetric spaces in the complex case and we study their basic integral kernels, in potential and spherical analysis: heat, Newton, Poisson kernels and spherical functions, i.e. the kernel of the spherical Fourier transform. We introduce and exploit a simple new method of construction of these W‐invariant kernels by alternating sum formulas. We then use the alternating sum representation of these kernels to obtain their asymptotic behavior. We apply our results to the Dyson Brownian Motion on Rd${\bf R}^d$.
Innovative and beneficial science stems from diverse teams and authorships that are inclusive of many perspectives. In this paper, we explore the status of inclusivity in remote sensing academic publishing, using an audit of peer-reviewed journal editorial board composition. Our findings demonstrate diversity deficiency in gender and country of residence, limiting the majority of editors to men residing in four countries. We also examine the many challenges underrepresented communities within our field face, such as implicit bias, harsher reviews, and fewer citations. We assert that in the field of remote sensing, the gatekeepers are not representative of the global society and this lack of representation restricts what research is valued and published, and ultimately who becomes successful. We present an action plan to help make the field of remote sensing more diverse and inclusive and urge every individual to consider their role as editor, author, reviewer, or reader. We believe that each of us have a choice to continue to align with a journal/institution/society that is representative of the dynamic state of our field and its people, ensuring that no one is left behind while discovering all the fascinating possibilities in remote sensing.
Magnetic data are widely available and useful in many exploration and applied-geophysics projects. The magnetic data are usually processed, imaged, and interpreted in commercial software packages. The algorithms used in these packages are sometimes difficult to check or tune, and the code is not available for review. However, these packages often have an application programming interface (API) for people to access data and undertake their own processing and data enhancement. In many cases, these APIs use the Python programming language. In the course of developing a new method for transforming magnetic data called reduction to pole and vertical dip (RTPVD), the initial test code was written in Python. This initial code was then rewritten and incorporated into GAMS, an open-source software package capable of using a Python API to read from and then write transformed (or enhanced) data to a commercial database. In addition to RTPVD, the other enhancements GAMS can generate are the zeroth-order analytic-signal amplitude (ASA 0 ), tilt, spatial derivatives of ASA 0 , the zeroth-order local wavenumber, the first-order analytic-signal amplitude, and the apparent susceptibility. These transformations require that the data be transformed to the wavenumber domain using a fast Fourier transform (FFT), operated on, and then transformed back to the space domain. The FFT and some of the preprocessing steps can be done with a number of built-in Python tools. For the preprocessing steps, some of the available Python options are fast, but they can occasionally introduce unwanted artifacts. Our open-source tool allows users to test the different options and check the intermediate steps to ensure the result is appropriate.
For the perspective of the latest happening news or some events occurring worldwide, social media is widely used and the reaction given by the people’s opinion is in the form of raw natural data in many languages and environments. All those written views have some unbalanced statements, i.e., some sensitive information or some slang words and uneven words. This makes opinion mining and making strategic decision useful in the future market. The structured and unbalanced data, Natural Language Processing (NLP) and Data Mining techniques are used for sentiment analysis. In the developed method, the study focuses on Twitter data on Citizenship Amendment Act of India, 2019 to detect the sentiment of the views from people all over the world using machine learning techniques. Many people had given their opinions and views about this new rule for CAA throughout that time. By purifying and analyzing the data using NLP techniques, VADER (Valence Aware Dictionary and sEntiment Reasoner) sentiment polarity is calculated. The dataset is normalized to be used by machine learning algorithms and prepared using natural language techniques such as Word Tokenization, Stemming and lemmatization, and Part of Speech (POS) Tagging. All that input variables are converted into vectors by Term Frequency-Inverse Document Frequency (TF-IDF). This method is implemented in a python programming language. The evaluation parameters such as accuracy, precision, recall, and F1-score were obtained for Naïve Bayes, SVM (support vector machine), K-Nearest Neighbor, Neural Network, Logistic Regression, Random Forest and LSTM (Long-short Term Memory) based RNN (Recurrent Neural Network). Finally, the results are compared. A One-way Analysis of Variance (ANOVA) test was performed on the mean values of performance metrics on all the methods.
The formulation of a one-dimensional model for the simultaneous evaluation of hydrodynamics and mass transfer in bubbly flow is presented in detail. The mass transfer due to the solubility kinetics and psychrometric aspects of the process is evaluated while accounting for the effects of process temperature and salinity of the liquid phase. While developed for downward co-current bubbly flow, the predictions of the model show good agreement with experimental data found in the literature for co-current upward bubble column. Using the model, the predicted profiles of pressure, temperature, liquid velocity, slip velocity, species’ gas-phase molar flow rate along the axis of the pilot HAC downcomer under selected scenarios are presented. Modelling of the pilot and demonstrator scale HAC downcomers suggest that the psychrometric aspects of the compression process will be the determining factor for selecting HAC operating temperatures. Modelling of gas absorption in aqueous electrolyte solutions suggest that an intent to reduce gas solubility may be defeated due to the reduction of bubble size and the resulting increase in interfacial area. Initialisation of liquid phase concentrations of gas species are discussed with simulations showing the diminishing absorption rate with repeated cycles of gas compression when no gas is removed. The potential impacts on the applications of compressed air production and carbon capture are also discussed.
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4,054 members
Ramya Narendrula
  • PhD in Biomolecular Sciences
Pawoumodom Matthias L. Takouda
  • Finance & Operations
Stephen D. Ritchie
  • School of Human Kinetics
Brahim Chebbi
  • School of Engineering
Jean-Charles, J.-Ch., JC Cachon
  • Marketing and Management
Greater Sudbury, Canada