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Cognitive therapy for compulsive checking in obsessive-compulsive disorder: A pilot trial
No full textWe evaluated a novel, empirically-based cognitive therapy for compulsive checking – a common form of obsessive-compulsive disorder. Twelve adults completed 12 sessions of the therapy. Significant reductions in checking-related symptoms were found pre- to post-treatment, and pre-treatment to 6-month follow-up (moderate to large effect sizes). Participants reported high treatment acceptability after the third session, which was maintained at post-treatment. This pilot trial provides preliminary support for treating compulsive checking using this novel cognitive approach
Bayesian risk assessment model of human cryptosporidiosis cases following consumption of raw Eastern oysters (Crassostrea virginica) contaminated with Cryptosporidium oocysts in the Hillsborough River system in Prince Edward Island, Canada
No full textCryptosporidium spp. has been associated with foodborne infectious disease outbreaks; however, it is unclear to what extent raw oyster consumption poses a risk to public health. Control of Cryptosporidium in shellfish harvest seawater in Canada is not mandatory and, despite relay/depuration processes, the parasite can remain viable in oysters for at least a month (depending on initial loads and seawater characteristics). Risks of human infection and illness from exposure to oysters contaminated with Cryptosporidium oocysts were assessed in a Bayesian framework. Two data sets were used: counts of oocysts in oysters harvested in Approved, Restricted, and Prohibited zones of the Hillsborough River system; and oocyst elimination rate from oysters exposed to oocysts in laboratory experiments. A total of 20 scenarios were assessed according to number of oysters consumed in a single serving (1, 10 and 30) and different relay times. The median probability of infection and developing cryptosporidiosis (e.g. illness) due to the consumption of raw oysters in Prince Edward Island was zero for all scenarios. However, the 95th percentiles ranged from 2% to 81% and from 1% to 59% for probability of infection and illness, respectively. When relay times were extended from 14 to 30 days and 10 oysters were consumed in one serving from the Restricted zones, these probabilities were reduced from 35% to 16% and from 15% to 7%, respectively. The 14-day relay period established by Canadian authorities for harvesting in Restricted zones seems prudent, though insufficient, as this relay period has been shown to be enough to eliminate fecal coliforms but not Cryptosporidium oocysts, which can remain viable in the oyster for over a month. Extending relay periods of 14 and 21 days for oysters harvested in Restricted zones to 30 days is likely insufficient to substantially decrease the probability of infection and illness. The highest risk was found for oysters that originated in Prohibited zones. Our findings suggest that Cryptosporidium oocysts are a potential cause of foodborne infection and illness when consuming raw oysters from Hillsborough River, one of the most important oyster production bays on Prince Edward Island. We discuss data gaps and limitations of this work in order to identify future research that can be used to reduce the uncertainties in predicted risks.Public Health Agency of CanadaFisheries and Oceans CanadaCanada Excellence Research Chair
Development of natural bio-links for neural cell bioprinting applications
No full textTissue engineering has played an exceptionally important role in addressing the increasing need for suitable tissue and organ replacements over the past few decades. Successful engineering of tissues that physiologically mimic their native counterparts relies on design and fabrication of temporary templates known colloquially as scaffolds. Scaffolds are commonly made of porous, biocompatible and often biodegradable biomaterials that enhance the cell and tissue growth and functionality. Among many scaffold engineering techniques, three-dimensional (3D) bioprinting is commonly used due to its ease of use and high speed of fabrication. In 3D bioprinting, a suspension of biomaterial, also known as bio-ink, is deposited in a layer-by-layer fashion to create the desired scaffold geometry according to a computer-aided design. An ideal bio-ink must be both “biocompatible” and “printable”: it must not impede the cell and tissue growth and it must retain the user-defined spatial arrangement following deposition from the printhead. It has been proven that all-natural bio-inks have high biocompatibility and reduced toxicity during degradation. Chitosan, starch, and agarose have all been used either on their own or as a blend
with other natural and synthetic polymers to create high performance bio-inks. The binary mixture of chitosan-starch and N,O-Carboxymethyl Chitosan (NOCC)-agarose have not been investigated for bioprinting applications of neurons. The objectives of this thesis are: 1. Investigate the suitability of starch and chitosan blends for cell seeding bioprinting applications; 2. Investigate the suitability of NOCC and agarose (ex. AG20NC80 = 20% agarose and 80% NOCC) blends for cell embedding bioprinting applications. To achieve objective 1, the printability and biocompatibility of chitosan and starch blend bio-inks
were investigated using a systematic framework. To consider the effects of flattening of filaments following deposition, the conventional framework was revised. Varying compositions of chitosan and starch blends were used to print scaffolds to grow neuron cells, and printability, cytotoxicity and cell viability for each scaffold were monitored. It was observed that, although increasing the potato starch content contributes to better printability of the bio-ink, more chitosan must be added to achieve higher biocompatibility. Therefore, a compromise in printability and biocompatibility must be made when starch and chitosan blends are used for scaffold fabrication. To achieve objective 2, the suitability of bio-inks composed of pure NOCC, pure agarose and their binary blends for applications in 3D bioprinting was investigated. The loss and storage moduli of each bio-ink were characterized, and it was observed that increasing the NOCC concentration enhances the rheological properties. The printability number for each bio-ink was determined and compared to the rheology results. The printability calculation was in agreement with the rheological studies. It was observed that while increasing the agarose concentration leads to a decrease in the rheological and printability properties of the bio-inks, it leads to an increase in cell viability. Therefore, when mixtures of agarose and NOCC are used, a balanced mixture of AG40NC60 is a suitable bio-ink in terms of biocompatibility as well as printability. With further development, these bio-inks could be used for a wide range of applications in the field of tissue engineering. In particular, in the long term, the scaffolds developed in this thesis can be used to create in-vitro models of the blood brain barrier (BBB). These models have the potential to be used for drug testing and consequently save the lives of many people who suffer from neurodegenerative diseases
Microbiome profiling reveals a microbial dysbiosis during a natural outbreak of tenacibaculosis (Yellow Mouth) in Atlantic salmon
No full textTenacibaculosis remains a major health issue for a number of important aquaculture species globally. On the west coast of Canada, yellow mouth (YM) disease is responsible for significant economic loss to the Atlantic salmon industry. While Tenacibaculum maritimum is considered to be the primary agent of clinical YM, the impact of YM on the resident microbial community and their influence on the oral cavity is poorly understood. Using a 16s rRNA amplicon sequencing analysis, the present study demonstrates a significant dysbiosis and a reduction in diversity of the microbial community in the YM affected Atlantic salmon. The microbial community of YM affected fish was dominated by two amplicon sequence variants (ASVs) of T. maritimum, although other less abundant ASVs were also found. Interestingly clinically unaffected (healthy) and YM surviving fish also had a high relative abundance of T. maritimum, suggesting that the presence of T. maritimum is not solely responsible for YM. A statistically significant association was observed between the abundance of T. maritimum and increased abundance of Vibrio spp. within fish displaying clinical signs of YM. Findings from our study provide further evidence that YM is a complex multifactorial disease, characterized by a profound dysbiosis of the microbial community which is dominated by distinct ASVs of T. maritimum. Opportunistic taxa, including Vibrio spp., may also play a role in clinical disease progression.Commonwealth Scientific and Industrial Research OrganisationCanada Excellence Research ChairsUniversity of Prince Edward Islan
Evaluating the added values of regional climate modeling over China at different resolutions
No full textPrevious studies have suggested that dynamical downscaling to global climate models can produce improved climate simulations at regional and local scales. However, the expensive computational requirements of dynamical downscaling inevitably add a limit to the spatial resolution of the resulting regional climate simulations. In order to find a balance between computational requirements and simulation improvements, it is extremely important to investigate how the spatial resolution of regional climate simulation affects the added values of dynamical downscaling; yet, it is still not well understood. Therefore, in this study, we conduct long-term climate simulations for the entire country of China with the PRECIS regional climate model at two different spatial resolutions (i.e., 25 and 50 km). The purpose is to evaluate whether a fine-resolution model simulation, given its considerable requirements for computational resources, would add more valuable information for understanding regional climatology than a coarse-resolution model simulation. Our results show that the PRECIS can reasonably reproduce the spatial distribution of seasonal and monthly mean temperature and precipitation over the most of regions in China. However, in the process of downscaling, RCM with higher resolution cannot always produce more accurate output. In regard to precipitation simulations, compared with the host GCM, it is difficult to determine exactly a homogeneous improvement of performance in downscaling, both in terms of spatial patterns as well as magnitude of errors. For interannual variability, variations in temperature are closer to observation than precipitation and the high-resolution R25 has better skills over the northwest than R50. Moreover, except for the west, it is shown that PRECIS is able to better reproduce the probability distribution function of precipitation and some impact-relevant indices such as the number of consecutive wet days and simple precipitation intensity index in spatial distribution
Development of a microbe domestication pod (MD Pod) for in situ cultivation of micro‐encapsulated marine bacteria
No full textMicrobial marine natural products hold significant potential for the discovery of new bioactive therapeutics such as antibiotics. Unfortunately, this discovery is hindered by the inability to culture the majority of microbes using traditional laboratory approaches. While many new methods have been developed to increase cultivability, a high‐throughput in situ incubation chamber capable of simultaneously isolating individual microbes while allowing cellular communication has not previously been reported. Development of such a device would expedite the discovery of new microbial taxa and, thus, facilitate access to their associated natural products. In this study, this concept is achieved by the development of a new device termed by the authors as the microbe domestication (MD) Pod. The MD Pod enables single‐cell cultivation by isolating marine bacterial cells in agarose microbeads produced using microfluidics, while allowing potential transmission of chemical signals between cells during in situ incubation in a chamber, or “Pod,” that is deployed in the environment. The design of the MD Pod was optimized to ensure the use of biocompatible materials, allow for simple assembly in a field setting, and maintain sterility throughout incubation. The encapsulation process was designed to ensure that the viability of marine sediment bacteria was not adversely impacted by the encapsulation process. The process was validated using representative bacteria isolated from temperate marine sediment samples: Marinomonas polaris, Psychrobacter aquimaris, and Bacillus licheniformis. The overall process appeared to promote metabolic activity of most representative species. Thus, microfluidic encapsulation of marine bacteria and subsequent in situ incubation in the MD Pod is expected to accelerate marine natural products discovery by increasing the cultivability of marine bacteria
Fabrication of microfluidic chips using controlled dissolution of 3D printed scaffolds
No full textMicrofluidic chips are commonly fabricated using soft lithography, which often requires a clean room and micropatterning equipment. Recently, microfluidic chips are increasingly fabricated using 3D printing, but this technology is still limited in smallest channel printability, transparency, supports residue, and biocompatibility. In this work, a simple, fast, and inexpensive step is introduced to fabricate polydimethylsiloxane (PDMS) microfluidic chips using enhanced internal scaffold removal (eISR). It is found that final channel dimension decreases by 0.22 ± 0.02 μm/revolution with a 7% error using eISR. Surface topology is inspected after dissolution using scanning electron microscopy. A T‐junction device, bifurcation channels, and curved channels are fabricated to demonstrate the usability of eISR in multiple applications. Compared to previous methods, eISR provides acrylonitrile–butadiene–styrene dissolution before PDMS casting to achieve thinner and smoother channels produced using a commercial 3D printer
Monte Carlo and Quasi Monte Carlo approach to Ulam's method for position dependent random maps
No full textWe consider position random maps T = {τ1(x), τ2(x),..., τK(x); p1(x), p2(x),..., pK(x)} on I = [0,1], where τk
, k =
1,2,...,K is non-singular map on [0,1] into [0,1] and {p1(x), p2(x),..., pK(x)} is a set of position dependent
probabilities on [0,1]. We assume that the random map T posses a density function f
∗ of the unique absolutely
continuous invariant measure (acim) µ
∗
. In this paper, first, we present a general numerical algorithm for the
approximation of the density function f
∗
. Moreover, we show that Ulam’s method is a special case of the general
method. Finally, we describe a Monte-Carlo and a Quasi Monte Carlo implementations of Ulam’s method for the
approximation of f
∗
. The main advantage of these methods is that we do not need to find the inverse images of
subsets under the transformations of the random map T
Fund managers’ association networks, information sharing and fund performance
No full textThis article studied the social network of fund managers based on their historical working relationships, and investigated how these relations influenced their information sharing as well as the fund performance. We found that (i) An investment portfolio with a high degree of information sharing had a high average return and Sharpe ratio. (ii) Fund managers’ degree of centrality in social networks had a significant positive effect on their information sharing and trading behaviours
