Dalhousie University
  • Halifax, NS, Canada
Recent publications
The need for objective measurement in psychiatry has stimulated interest in alternative indicators of the presence and severity of illness. Speech may offer a source of information that bridges the subjective and objective in the assessment of mental disorders. We systematically reviewed the literature for articles exploring speech analysis for psychiatric applications. The utility of speech analysis depends on how accurately speech features represent clinical symptoms within and across disorders. We identified four domains of the application of speech analysis in the literature: diagnostic classification, assessment of illness severity, prediction of onset of illness, and prognosis and treatment outcomes. We discuss the findings in each of these domains, with a focus on how types of speech features characterize different aspects of psychopathology. Models that bring together multiple speech features can distinguish speakers with psychiatric disorders from healthy controls with high accuracy. Differentiating between types of mental disorders and symptom dimensions are more complex problems that expose the transdiagnostic nature of speech features. Convergent progress in speech research and computer sciences opens avenues for implementing speech analysis to enhance objectivity of assessment in clinical practice. Application of speech analysis will need to address issues of ethics and equity, including the potential to perpetuate discriminatory bias through models that learn from clinical assessment data. Methods that mitigate bias are available and should play a key role in the implementation of speech analysis.
The Prince Edward Island (PEI) mussel aquaculture industry is being challenged by climate change induced environmental stressors including hypoxic/anoxic episodes, that can impact mussel health and survival. Physiological responses of mussels to hypoxia/anoxia have been studied; however, less is known about how transcriptomic response leads to physiology. The present study examined the transcriptomic response of acute (4 h) hypoxia in blue mussels (Mytilus edulis) from two sites and size classes in PEI, Canada. Overall, major changes in whole-mussel transcriptomics associated with metabolism, cellular organelles/processes and environmental sensing were observed in the first hours of hypoxia exposure. Differences in differentially expressed transcripts were observed between each site and size, indicating that responses to acute hypoxia exposure are highly complex. A size related pattern was observed, with seed size mussels having differential expression of transcripts associated with development, muscle function, and byssal attachment compared to the adults. Adult mussels had higher HSP 90 expression, while HSPs were predominately under-expressed in seed mussels. Seed mussels had significant under-expression of several classes of byssal thread attachment transcripts, indicating a decline in the production of byssal thread or detachment, both which have negative consequences for mussel aquaculture. Keywords: Dissolved oxygen; Hypoxia; Mussels; Gene expression; Climate change; Transcriptome
The multilabel learning task aims to predict the associated multiple classes of a given example simultaneously. Such task becomes more challenging when data arrives in stream since it requires concept drift adaptative, robust, and fast algorithm. In this article, we present an online semi-supervised classification algorithm () for multilabel text streams. By leveraging a few labeled instances, dynamically maintains the subspace of terms for each label with a set of evolving micro-clusters. For multilabel classification, $k$ nearest micro-clusters are employed for prediction by using a nonparametric Dirichlet model. To handle the gradual concept drift in term space, the triangular time function is adopted to calculate the difference between term arriving time and cluster life span. Whereas, abrupt concept drift is dealt by considering two procedures: 1) deleting outdated micro-cluster by exploiting the exponential decay function and 2) creating new micro-clusters by adopting the Chinese restaurant process based on the Dirichlet process. The conducted experimental study provides a comparison with 12 state-of-the-art algorithms on nine datasets in terms of classification performance, runtime, and memory consumption.
Effects of season and mixing on hydrocarbon concentrations and the microbial community response was explored in a series of mesocosm experiments simulating surface spills of diesel into coastal waters. Mixing of any amount contributed to hydrocarbons entering the water column, but diesel fuel composition had a significant effect on hydrocarbon concentrations. Higher initial concentrations of aromatic hydrocarbons resulted in higher water column concentrations, with minimal differences among seasons due to high variability. Regardless of the concentrations of hydrocarbons, prokaryotes increased and there were higher relative abundances of hydrocarbon affiliated bacteria with indications of biodegradation within 4 d of exposure. As concentrations decreased over time, the eukaryote community shifted from the initial community to one which appeared to be composed of organisms with some resilience to hydrocarbons. This series of experiments demonstrates the wide range of conditions under which natural attenuation of diesel fuel is an effective response.
Plain Language Summary While many studies have been devoted to understanding the processes and mechanisms underlying the sea surface temperature (SST) cooling induced by tropical cyclones (TCs), few studies have attempted to predict the spatial and temporal evolution of the sea surface temperature (SST) cooling triggered by TCs. In this study, we proposed to achieve this goal by building a model using an efficient and robust machine learning‐based method. The constructed model uses 12 predictors associated with TC characteristics (e.g., intensity, and translation speed) and pre‐storm ocean states (e.g., mixed layer depth). The model performs well in producing the TC‐induced spatial structure and temporal evolution of the cold wake and can capture most of the variance in the observed SST response. We quantified the relative importance of the 12 predictors, and found that TC intensity, translation speed and size, and pre‐storm mixed layer depth and SST dominate in deciding the magnitude of the SST response. The results and proposed method have important implications for predicting the response of ocean primary production to the TC wind pump effects.
Historical fishing effort has resulted, in many parts of the ocean, in increasing catches of smaller, lower trophic level species once larger higher trophic level species have been depleted. Concurrently, changes in the geographic distribution of marine species have been observed as species track their thermal affinity in line with ocean warming. However, geographic shifts in fisheries, including to deeper waters, may conceal the phenomenon of fishing down the food web and effects of climate warming on fish stocks. Fisheries-catch weighted metrics such as the Mean Trophic Level (MTL) and Mean Temperature of the Catch (MTC) are used to investigate these phenomena, although apparent trends of these metrics can be masked by the aforementioned geographic expansion and deepening of fisheries catch across large areas and time periods. We investigated instances of both fishing down trophic levels and climate-driven changes in the geographic distribution of fished species in New Zealand waters from 1950-2019, using the MTL and MTC. Thereafter, we corrected for the masking effect of the geographic expansion of fisheries within these indices by using the Fishing-in-Balance (FiB) index and the adapted Mean Trophic Level (aMTL) index. Our results document the offshore expansion of fisheries across the New Zealand Exclusive Economic Zone (EEZ) from 1950-2019, as well as the pervasiveness of fishing down within nearshore fishing stock assemblages. We also revealed the warming of the MTC for pelagic-associated fisheries, trends that were otherwise masked by the depth-and geographic expansion of New Zealand fisheries across the study period.
Background In June 2016, Canada legalized medical assistance in dying (MAiD). From the outset, some healthcare institutions (including faith-based and non-faith-based hospitals, hospices, and residential aged care facilities) have refused to allow aspects of MAiD onsite, resulting in patient transfers for MAiD assessments and provision. There have been media reports highlighting the negative consequences of these “institutional objections”, however, very little research has examined their nature and impact. Methods This study reports on findings from 48 semi-structured qualitative interviews conducted with MAiD assessors and providers, MAiD team members (working to coordinate care and lead MAiD programs in institutions and health authorities), and family caregivers on their experiences with institutional objection. Participants were recruited from the Canadian provinces of British Columbia, Ontario, and Nova Scotia. Data were analyzed using inductive thematic analysis. Results Themes identified were: (1) basis for institutional objection (with objections commonly rooted in religious values and a particular philosophy of palliative care); (2) scope of objection (demonstrating a wide range of practices objected to); (3) lack of transparency regarding institutional position; (4) impacts on patients; (5) impacts on health practitioners; and (6) catalysts for change. Participants reported that many institutions’ objections had softened over time, lessening barriers to MAiD access and adverse impacts on patients and health practitioners. Participants attributed this positive change to a range of catalysts including advocacy by health practitioners and family members, policymaking by local health authorities, education, and relationship building. Nevertheless, some institutions, particularly faith-based ones, retained strong objections to MAiD, resulting in forced transfers and negative emotional and psychological impacts on patients, family members, and health practitioners. Conclusions This paper adds to the limited evidence base about the impacts of institutional objection and can inform practical and regulatory solutions in Canada and abroad. Reform is needed to minimize the negative impacts on patients, their caregivers, and health practitioners involved in MAiD practice.
Objective This study proposes to identify and validate weighted sensor stream signatures that predict near-term risk of a major depressive episode and future mood among healthcare workers in Kenya. Approach The study will deploy a mobile application (app) platform and use novel data science analytic approaches (Artificial Intelligence and Machine Learning) to identifying predictors of mental health disorders among 500 randomly sampled healthcare workers from five healthcare facilities in Nairobi, Kenya. Expectation This study will lay the basis for creating agile and scalable systems for rapid diagnostics that could inform precise interventions for mitigating depression and ensure a healthy, resilient healthcare workforce to develop sustainable economic growth in Kenya, East Africa, and ultimately neighboring countries in sub-Saharan Africa. This protocol paper provides an opportunity to share the planned study implementation methods and approaches. Conclusion A mobile technology platform that is scalable and can be used to understand and improve mental health outcomes is of critical importance.
Polyethylene terephthalate (PET) tape is widely used by well-known lithium-ion battery manufacturers to prevent electrode stacks from unwinding during assembly. PET tape is selected since it has suitable mechanical and electrical properties, but its chemical stability has been largely overlooked. In the absence of effective electrolyte additives, PET can depolymerize into its monomer dimethyl terephthalate, which is an unwanted redox shuttle that induces substantial self-discharge in a lithium-ion cell. This study presents a chemical screening experiment to probe the PET decomposition mechanism involving in situ generated methanol and lithium methoxide from dimethyl carbonate, one of the most common electrolyte solvents in lithium-ion cells. By screening other polymers, it is found that polypropylene and polyimide (Kapton) are stable in the electrolyte. Finally, it is demonstrated that reversible self-discharge of LiFePO4–graphite cells can be virtually eliminated by replacing PET jellyroll tape with chemically stable polypropylene tape.
We show how, given positive constants \(\epsilon \) and \(\delta \), and an \(\alpha \)-balanced straight-line program with g rules for a text T[1..n], we can build an O(g)-space index that, given a pattern P[1..m], in \(O(m\log ^\delta g)\) time finds w.h.p. a substring of P that occurs in T and whose length is at least a \((1 - \epsilon )\) fraction of the longest common substring of P and T. The correctness can be ensured within the same expected query time.
The positional Burrows–Wheeler Transform (PBWT) was presented as a means to find set-maximal exact matches (SMEMs) in haplotype data via the computation of the divergence array. Although run-length encoding the PBWT has been previously considered, storing the divergence array along with the PBWT in a compressed manner has not been as rigorously studied. We define two queries that can be used in combination to compute SMEMs, allowing us to define smaller data structures that support one or both of these queries. We combine these data structures, enabling the PBWT and the divergence array to be stored in a manner that allows for finding SMEMs. We estimate and compare the memory usage of these data structures, leading to one data structure that is most memory efficient. Lastly, we implement this data structure and compare its performance to prior methods using various datasets taken from the 1000 Genomes Project data.
Recently, Conte et al. generalized the longest-common prefix (LCP) array from strings to Wheeler DFAs, and they showed that it can be used to efficiently determine matching statistics on a Wheeler DFA [DCC 2023]. However, storing the LCP array requires \( O(n \log n) \) bits, n being the number of states, while the compact representation of Wheeler DFAs often requires much less space. In particular, the BOSS representation of a de Bruijn graph only requires a linear number of bits, if the size of alphabet is constant. In this paper, we propose a sampling technique that allows to access an entry of the LCP array in logarithmic time by only storing a linear number of bits. We use our technique to provide a space-time trade-off to compute matching statistics on a Wheeler DFA. In addition, we show that by augmenting the BOSS representation of a k-th order de Bruijn graph with a linear number of bits we can navigate the underlying variable-order de Bruijn graph in time logarithmic in k, thus improving a previous bound by Boucher et al. which was linear in k [DCC 2015].
This paper presents a way to compactly represent dynamic connected planar embeddings, which may contain self loops and multi-edges, in \(4m + o(m)\) bits, to support basic navigation in \(O(\lg n)\) time and edge and vertex insertion and deletion in \(O(\lg ^{1+\epsilon }n)\) time, where n and m are respectively the number of vertices and edges currently in the graph and \(\epsilon \) is an arbitrary positive constant. Previous works on dynamic succinct planar graphs either consider decremental settings only or are restricted to triangulations where the outer face must be a simple polygon and all inner faces must be triangles. To the best of our knowledge, this paper presents the first representation of dynamic compact connected planar embeddings that supports a full set of dynamic operations without restrictions on the sizes or shapes of the faces.
Complex paediatric health conditions are increasingly associated with survival into adulthood resulting in more youth with complex care needs (CCN) transitioning from paediatric to adult healthcare. Current transition practices, when present, are disorganized, resulting in health status deterioration and complications due to unmet needs. The aim of this qualitative descriptive study is to develop a broader understanding of the current transition practices and experiences, as well as recommendations of care providers who support youth with CCN in the transition from paediatric to adult healthcare. Fifteen care providers from two Eastern Canadian provinces were interviewed using a semi-structured interview guide. The data collected were analyzed using inductive thematic analysis following the six phases outlined by Braun and Clarke (2006). The findings from this research demonstrate (1) a shortage of care providers, (2) inconsistent timing for transition initiation, and (3) lack of available community resources and services. Participant recommendations include (1) a designated transition coordinator; (2) transition policy implementation; (3) improved collaboration between and across care teams; and (4) the integration of virtual care to facilitate the transition process. The results of this study can potentially improve transition practices and policies and guide future research in this area.
Peripartum pain has been associated with postpartum depression (PPD), and labour epidural analgesia (LEA) may be able to modify this risk. The objective of this historical cohort study was to examine the association between LEA and PPD among primiparous patients. With institutional research ethics board approval, a provincial perinatal database was searched for primiparous patients who delivered a liveborn singleton infant between 2004 and 2018. Those patients who experienced PPD following their first delivery were identified by a history of PPD in the perinatal records of their second pregnancy. We used logistic regression to compute odds ratios (ORs) for the association between LEA and PPD and performed an adjusted analysis to control for confounding variables. A total of 35,437 primiparous patients were identified, 67% (n = 23,599) of whom received LEA. In the cohort, 3.7% (n = 1,296) of patients developed PPD. Patients who received LEA had increased odds of developing PPD compared with patients who did not receive LEA (adjusted OR, 1.29; 95% confidence interval [CI], 1.12 to 1.48). In a multivariable regression model, LEA remained a significant predictor for PPD, as did body mass index, pre-existing anxiety, and maternal antidepressant use. This historical cohort study found an association between LEA and PPD among primiparous patients who subsequently had a second pregnancy in the same province. The findings call into question the hypothesis that LEA decreases the risk for PPD and further illustrates the complexities of PPD.
Background Because of critical shortage of physician anaesthesiologists, the government of Tanzania adopted a task shifting strategy for provision of anaesthesia services. This paper describes the results of an operational study designed to increase the number of anaesthesia providers for emergency obstetric surgeries in order to reduce maternal and perinatal mortality in underserved rural Tanzania. Methods In 2016 a before-after cohort study was conducted in seven health centres in rural Tanzania. Five health centres received an intervention and two were selected to track secular trends (control group). Ten associate clinicians, i.e. assistant medical officers, clinical officers, and nurse midwives, from five health centres were trained in anaesthesia skills for emergency obstetric surgeries for three months followed by quarterly supportive supervision, mentoring and teleconsultation to reinforce skills. Primary and secondary outcome measures included Caesarean delivery (CD) rate, quality and safety of anaesthesia, and uptake of the educational program for anaesthesia. Results Out of the 2,179 CDs performed in the intervention facilities from 2016 to 2019, two women died from complications of anaesthesia. The risk of death from anaesthetic complications was 0.9 per 1000 CD (95% CI 0.1–3.3. The risk of death was not established in the control group because of inadequate documentation and records keeping. The proportion of CD performed under spinal anaesthesia in intervention facilities doubled from 28% (60/214 with 95% CI 22–35) at baseline (July 2014 – June 2016) to 57% (558/971 with 95% CI of 54–61) in year three (July 2018 - June 2019), while in the control group increased by only 40% from 19% (92/475 with 95% CI of 16–23) at baseline and 27% (68/251 with 95% CI of 22–33) in year three. In 2020I, this educational training program was then adopted by the government with minor content changes and increasing duration of training to six months. Conclusions This three month educational training program for associate clinicians in anaesthesia, complemented by supportive supervision, can increase the CD rate to one that fills the “unmet need” and the proportion of operations performed under spinal anaesthesia, the gold standard technique for CD. The program can be used to meet the urgent demand for anaesthesia services in other underserved areas in Africa.
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11,903 members
Manuel Mattheisen
  • Department of Community Health & Epidemiology
Robert Wingate Lee
  • Department of Biology
Deborah Adewole
  • Department of Animal Science and Aquaculture
Petra Mudie
  • Faculty of Graduate Studies
6100 University Ave, Suite 5010, PO Box 15000, B3H 4R2, Halifax, NS, Canada
Head of institution
Deep Saini