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Freshwater tolerance and mechanisms of freshwater acclimation in marine sticklebacks (Gasterosteus spp.)
Get PDF1 online resource (69 pages) : charts, graphsIncludes abstract and appendix.Includes bibliographic references (pages 63-69).Freshwater tolerance has evolved repeatedly in fishes, including in the Gasterosteidae family. However, Blackspotted Stickleback (Gasterosteus wheatlandi) and the endemic
Nova Scotian “white” Threespine Stickleback (Gasterosteus aculeatus) ecotype are largely
limited to marine environments. I tested if low freshwater tolerance might limit the
distribution of these fishes. Freshwater tolerance was assessed in wild caught fish
acclimated to 10 ppt and then transferred to freshwater (0 ppt) or control conditions (10
ppt) for a period of 21 days. There was no effect of salinity on survivorship or tissue water
content (a proxy for osmoregulatory homeostasis) in either species. mRNA content of
candidate gill ion transporters was measured via qPCR in Blackspotted Stickleback, and I
found this marine species can initiate the transcriptional changes associated with successful
freshwater acclimation in other sticklebacks. These data suggest that acute freshwater
tolerance does not limit initial freshwater colonization in these species
On path length, beam divergence, and retroreflector size in open path FTIR spectroscopy
Get PDF1 online resource (x, 78 pages) : colour illustrationsIncludes abstract and appendices.Includes bibliographical references (pages 75-78).Open-Path Fourier Transform InfraRed (OP-FTIR) spectroscopy is an established technique used to measure boundary layer trace gas concentrations, consisting of a spectrometer and a retroreflector separated by a measurement path. The detection limit is directly proportional to the optical path, which controls target gas spectral absorption feature depth; however, depending on the specifics of the spectrometer and telescope optics, beam divergence can begin overfilling the distant retroreflector array for paths greater than ~300 m, resulting in decreased returning radiation. In this case, the absorption signature of the target gas increases, but the signal to noise ratio of the recorded spectrum does not, making detection difficult. The results of an experiment where the retroreflector array area was increased to collect a larger fraction of returning radiation at path lengths ranging from ~200 m – 1000 m are discussed, including an analysis of both underlying spectra and quality indicators for retrieved concentrations of carbon monoxide. The results show that the larger retroreflector array results in smaller decreases in the signal-to-noise ratio as a function of the measurement path when compared to a smaller array. Next, the effectiveness of cleaning retroreflector arrays after extended field use is presented using quantitative information, including 1) a measured 10% increase in infrared intensity and 3) surface characterization of a single retroreflector cube corner array before and after the cleaning process, which resulted in no notable changes, but revealed corrosive processes and contaminants present on the cube. Lastly, the results of theoretical spectral simulations are discussed in detail for CO and HCHO (formaldehyde) showing how path length, water concentration, and target concentration affect the differential absorption spectrum of the target, also considering random and systematic noise levels. It was determined that path lengths > 300 m are necessary for robust HCHO measurements. A further 10 common atmospheric species are explored in Appendix B. Finally, spectral simulations also explore the relationship between absorbance and transmittance by increasing the target gas concentration, from which it is seen that for less abundant trace gases (i.e., HCHO at 1 ppb) concentration and transmittance are approximately linearly related
“Houses still standing” : modernity, myth and memory on Nova Scotia’s Devil’s Island
Get PDF1 online resource (67 pages) : illustrationsIncludes abstract and appendix.Includes bibliographical references (pages 56-61).Once known as the "singing island" by folklorist Helen Creighton, Nova Scotia's Devil's Island has been sorely neglected by academics. By uncovering its history, mapping the community, and exploring Creighton's role in perpetuating the island's folk identity, this paper will examine the influence of the island on Creighton's later archival work. In exploring the island's shifting identity, from the epitome of true folk to an abandoned ghost village, this paper will also show how both identities promoted by Creighton contribute to her manufactured idea of the folk, which was later exploited by the tourism sector. This study also examines the effects of the relocation during WWII on former residents, exploring their inability to move back to the island after the war. With the recent passing of many former residents, "an intimate fund of memory" has disappeared and Devil's Island has become what Pierre Nora refers to as a lieu de mémoire. Using interviews from former residents and their descendants collected in 1998 and 2021, my paper will examine the disparity between second-hand memory and the childhood nostalgia for a lost place. This paper examines collected memories to highlight how the physical loss of the island contributed to the intense nostalgia and collective longing for a place no longer in existence. Applying both Pierre Nora's theory on the interconnectedness of history and memory and Maurice Halbwachs' theory of collective memory, I will analyze the shared memory and community experienced by former residents even after their displacement
Assessing the probable distribution of the potentially invasive Chinese mystery snail, Cipangopaludina chinensis, in Nova Scotia using a random forest model approach
Get PDFPublished versionNon-native species that become invasive threaten natural biodiversity and can lead
to socioeconomic impacts. Prediction of invasive species distributions is important
to prevent further spread and protect vulnerable habitats and species at risk (SAR)
from future invasions. The Chinese mystery snail, Cipangopaludina chinensis, native
to Eastern Asia, is a non-native, potentially invasive, freshwater snail now widely
established across North America, Belgium, and The Netherlands. This species was
first reported in Nova Scotia, eastern Canada in 1955, but was not found to be
established until the 1990s and now exists at high densities in several urban lakes.
Nonetheless, the presence and potential distribution of this species in Nova Scotia
remains unknown. Limited resources make it difficult to do a broad survey of
freshwater lakes in Nova Scotia, however a species distribution probability model
has the potential to direct focus to priority areas. We apply a random forest model
in tandem with a combination of water quality, fish community, anthropogenic
water use, and geomorphological data to predict C. chinensis habitat in Nova Scotia
(NS), Canada. All predicted probabilities of suitable C. chinensisi habitats in Nova
Scotia were > 50% and include Cape Breton Island, the Nova Scotia-New Brunswick
border, and the Halifax Regional Municipality. Suitable habitats predicted for
C. chinensis overlap with many SAR habitats, most notably brook floater mussel,
Alasmidonta varicosa, and yellow lampmussel, Lampsila cariosa. Our results indicate
that C. chinensis could become widespread throughout NS, appearing first in the
aforementioned areas of highest probability. Further research is required to test
C. chinensis ecological thresholds in order to improve the accuracy of future
species distribution and habitat models, and to determine C. chinensis impacts on
native freshwater mussel populations of conservation concern
Searching for the signature of a tetraneutron resonance
Get PDF1 online resource (ix, 101 pages) : illustrations, (chiefly colour)Includes abstract and appendices.Includes bibliographical references (pages 100-101).Many environments in the universe give rise to conditions extreme enough to allow exotic forms of nuclear matter. Understanding how this matter interacts allows us to better understand the nuclear forces and astronomical phenomena such as neutron stars. A tetraneutron is an exotic nuclear form which is composed of four neutrons. Its existence is debated, with an open question whether they can be held together briefly in a short-lived resonant state. The existence of the tetraneutron state would be observable in reactions with four neutrons as their end product. At the IRIS facility at TRIUMF, an experiment involving the reaction 8He(d, 6Li)4n was carried out by reacting a beam of 8He with a deuterium target and measuring the kinematics of the resulting 6Li. The existence of the tetraneutron state could be determined from the missing mass spectrum. In order to be able to interpret the results of the experiment, the effect of the non-resonant four neutron final state must be determined. This is done by simulating the non-resonant reaction with five-body final state through the experimental setup. This thesis covers my work in building this simulation using the properties of the reaction and the experimental setup
Digital quarantine : does social distancing lead to virtual distancing?
Get PDF1 online resource (vi, 40 pages) : colour illustrationsIncludes abstract.Includes bibliographical references (pages 37-39).During the COVID-19 pandemic, public health officials actively promoted messaging on quarantine, isolation, and social distancing to reduce viral transmission and keep people safe. This paper examines the possibility of spillover effects that isolation-oriented interventions may have in a non-physical domain, specifically digital behaviors. While users indeed spend more time online during the pandemic, this may also manifest as a meaningful change in digital behaviors—people are engaging less online. Evidence from four studies reveal that users are sharing less news content, commenting less on discussion boards, engaging less with popular social media accounts, and even changing their search query behavior to fulfill peripheral safety needs (i.e., anti-virus software) in the wake of the pandemic. This paper documents an unintended consequence of isolation rhetoric in health promotion and, by identifying changes to our digital behaviors, this paper suggests ways to develop interventions to bolster social connectedness and collective mental health
ESG transparency on firm performance : an empirical research of Covid-19 in global logistics firms
Get PDF1 online resource (v, 60 pages)Includes abstract and appendix.Includes bibliographical references (pages 59-60).Supply chain management (SCM) facilitated by the forces of globalization
and technology evolution was playing an unassailable role in serving the
world. The impact of Covid-19 caused disruption to these supply chains.
The objective of this paper is to investigate the quasi-potential impact of the
environment, social, and governance (ESG) disclosure on the firms’
performance in the transportation and logistics industry and the influence of
the pandemic.
The empirical analysis, conducted on a sample of worldwide publicly traded
companies, shows that the ESG disclosure score (ESGD) especially ESGD
at higher level significantly contributes to firm value despite a relatively
lower level of ESGD increases with a drop in firm value at the onset of the
Covid-19 pandemic. As expected, the results also indicate that the effect of
ESGD is significantly associated with a positive change in firm value during
the pandemic and post-pandemic period
The impact of victim impact statements
Get PDF1 online resource (viii, 263 pages) : colour illustrationsIncludes abstract and appendices.Includes bibliographical references (pages 195-222).Victim impact statements (VIS) are testimonies that convey the emotional, physical, and financial harm that victims have suffered as the result of a crime. This study sheds light on this victims' experiences with the justice system, and consists of two studies designed to explore the impact of victim impact statements. Study 1 examined 1332 sentencing rulings to discover the relationship between VIS and sentencing. Overall, VIS do not contribute to longer custodial sentences. However, VIS are more likely to be submitted in cases where the crime is more severe. Study 2 of this thesis was a content analysis of 82 Canadian VIS. Overall, victims find the process of writing and submitting VIS to be retraumatizing and difficult. They most commonly discuss the long-lasting emotional impacts of crime. These findings have implications for victims, victim service workers, legal professionals, and others in our justice system
2021-03-02 Senate Minutes and Agendas
No full textMinutes and agenda for the March 2nd, 2021 meeting of Saint Mary's University Senate
Investigation of enhancement of growth in Sorghum bicolor by inoculation with plant growth-promoting microbes
Get PDF1 online resource (170 pages) : illustrations (chiefly colour)Includes abstract and appendices.Includes bibliographical references (pages 117-132).Hybrids of Sorghum bicolor (L.) Moench have potential as second-generation biofuel feedstock crops in Canada. This study's objective was to screen five plant growth-promoting microbial strains (Gluconacetobacter diazotrophicus PAL5T, G. azotocaptans DS1, Azospirillum lipoferum N7, A. brasilences N8 and Penicillium bilaii) for growth-enhancing effects on four sorghum genotypes. Two greenhouse studies and one field study were conducted. Glocanoacetobacter diaztrophicus (PAL5T)-treated CSSH 45 cultivar showed a significant increase in shoot dry weight by 19%, in N content by 27% and in P content by 37% compared to uninoculated control plants in one of the greenhouse studies. None of the microbial inoculants significantly increased growth of the sorghum in the field, although Azospirillum brasilense (N8) treated genotypes consistently had the highest mean shoot dry weight. According to the overall results of the study, PAL5T and N8 may offer the greatest potential for use as growth-promoting bacteria in sorghum production