Soare R.J.,Dawson College |
Conway S.J.,Open University Milton Keynes |
Dohm J.M.,Tokyo Institute of Technology
Icarus | Year: 2014
The Argyre basin and associated rim-materials in the southern hemisphere of Mars are ancient, having been formed by the impact of a large body ~4. Gya. This notwithstanding, the regional landscape continues to be altered by a multiplicity of geological and geomorphological processes.Three landforms, whose close spatial-association is identified in a new geological map of the Argyre region (~290-360°E; ~30-72°S), feature prominently in the list of very Late Amazonian Epoch alterations:. (a)Small-sized (≤~20m in diameter) and unsorted polygons that exhibit metre to sub-metre elevated margins or shoulders, giving them a low-centred appearance; in "wet" permafrost environments on Earth low-centred polygons (LCPs) often are underlain by ice-wedges.(b)Gullies, seemingly formed by "wet" flow(s) and incised by the LCPs.(c)A putative (possibly ice-rich) latitude-dependent mantle (LDM) that underlies the LCPs and spatially-convergent "wet" gullies in all of our observations.These landforms occur from the middle to the high (near-polar) latitudes of the region and overlie geological units of all ages.Hitherto, the presence of the LCPs has been reported only fleetingly in the literature and only in as much as they have been observed on the walls of a few scalloped depressions in mid-Utopia Planitia. By contrast, we report the ubiquitous occurrence of the LCPs in and around the Argyre impact-basin on gully-margins and adjacent slopes as well as on relatively-flat inter-crater terrain.On the basis of three separate but related lines of reasoning we hypothesise that ice wedges could be present beneath LCP margins in our study region. If we are correct then these LCP sites are geomorphological expressions of boundary conditions that were relatively warm and wet in the recent past.First, substantial ice-wedging in permafrost environments on Earth requires the availability of meltwater. If, as some researchers propose, the formation of some "wet" gullies at the martian mid-latitudes is induced by the localised (slope-side and crater-wall) thaw of the underlying LDM at the gully sites themselves, then meltwater also should be available for ice-wedging and the formation of LCPs at these sites. Interestingly, LCPs are observed on gully-channel walls as expected if meltwater is associated with gully formation; however, in some instances the LCPs are also observed on the slope-side terrain that extends for hundreds of metres beyond the channel walls and even above the gully alcoves. This suggests that the distribution of icy terrain affected by thaw could be much more substantial than has been suggested hitherto.Second, LCPs that are identical in shape and scale to the slope-side LCPs are observed on relatively flat inter-crater terrain (also underlain by the LDM) that is distal from the "wet" gullies. By contrast, here, their distribution extends for kilometres. This too could be indicative of meltwater being more extensive in the regional landscape than most workers have thought possible.Third, on Earth the "dryness" or the "wetness" of a permafrost environment determines whether LCP margins are underlain by sand or by ice. When the observed LCPs and major deposits of sand in the study region are plotted on our new map of the Argyre impact-basin, we see that these deposits are rarely proximal. On the other hand, the LDM underlies the LCPs in all instances and, if modified by thaw, seems to be a likelier source of margin fill for the LCPs than sand. © 2014 Elsevier Inc.
Soare R.J.,Dawson College |
Conway S.J.,Open University Milton Keynes |
Dohm J.M.,University of Tokyo |
El-Maarry M.R.,University of Bern
Earth and Planetary Science Letters | Year: 2014
We report the observation of possible (hydraulic) open-system pingos (OSPs) at the mid latitudes (~37°S) in and around the Argyre impact-basin. OSPs are perennial (water)-ice cored mounds; they originate and evolve in periglacial and pro-glacial landscapes on Earth where intra- or sub-permafrost water under hydraulic/artesian pressure uplifts localised sections of surface or near-surface permafrost that then freezes in-situ. We invoke three lines of evidence in support of our analogue-based interpretation: (1) similarities of shape, size and summit traits between terrestrial OSPs and the Martian mounds; (2) clustered distribution and the slope-side location of the mounds, consistent with terrestrial permafrost-environments where OSPs are found; and, (3) spatially-associated landforms putatively indicative of periglacial and glacial processes on Mars that characterise OSP landscapes on Earth.This article presents five OSP candidate-locations and nests these mound locations within a new geological map of the Argyre impact-basin and margins. It also presents three periglacial hypotheses about the possible origin of the water required to develop the mounds. Alternative (non-periglacial) formation-hypotheses also are considered; however, we show that their robustness is not equal to that of the periglacial ones. © 2014 Elsevier B.V.
News Article | November 3, 2016
With an upcoming publication in the Worldwide Leaders in Healthcare, Anna Zeitounian-Pucci, RN, joins the prestigious ranks of the International Nurses Association. Anna is a Registered Nurse with 32 years of experience in her field and an extensive expertise in all facets of nursing, especially as a Coordinator in Private Nursing. Anna is currently serving patients in Quebec, Canada. Anna received her Nursing Degree at Dawson College in Montreal, Quebec, Canada. She holds certification in Thanatology, and enjoys reading The American Journal of Nursing. Anna attributes her success to her approach towards her clientele: she listens, understands, and does not judge. When she is not assisting patients, Anna enjoys yoga and running, as well as being around animals. Learn more about Anna here: http://inanurse.org/network/index.php?do=/4131845/info/ and read her upcoming publication in the Worldwide Leaders in Healthcare.
Gaskin S.,McGill University |
Gaskin S.,Dawson College |
White N.M.,McGill University
Hippocampus | Year: 2013
The conditioned cue preference paradigm was used to study how rats use extra-maze cues to discriminate between 2 adjacent arms on an 8-arm radial maze, a situation in which most of the same cues can be seen from both arms but only one arm contains food. Since the food-restricted rats eat while passively confined on the food-paired arm no responses are reinforced, so the discrimination is due to Pavlovian stimulus-reward (or outcome) learning. Consistent with other evidence that rats must move around in an environment to acquire a spatial map, we found that learning the adjacent arms CCP (ACCP) required a minimum amount of active exploration of the maze with no reinforcers present prior to passive pairing of the extra-maze cues with the food reinforcer, an instance of latent learning. Temporary inactivation of the hippocampus during the pre-exposure sessions had no effect on ACCP learning, confirming other evidence that the hippocampus is not involved in latent learning. A series of experiments indentified a circuit involving fimbria-fornix and dorsal entorhinal cortex as the neural basis of latent learning in this situation. In contrast, temporary inactivation of the entorhinal cortex or hippocampus during passive training or during testing blocked ACCP learning and expression, respectively, suggesting that these two structures co-operate in using spatial information to learn the location of food on the maze during passive pairing and to express this combined information during testing. In parallel with these processes we found that the amygdala processes information leading to an equal tendency to enter both adjacent arms (even though only one was paired with food) suggesting that the stimulus information available to this structure is not sufficiently precise to discriminate between the ambiguous cues visible from the adjacent arms. Expression of the ACCP in normal rats depends on hippocampus-based learning to avoid the unpaired arm which competes with the amygdala-based tendency to enter that arm. In contrast, there is cooperation between amygdala- and hippocampus-based tendencies to enter the food-paired arm. These independent forms of learning contribute to the rat's ability to discriminate among spatial locations using ambiguous extra-maze cues. © 2013 Wiley Periodicals, Inc.
Neher A.,Dawson College
Medical Humanities | Year: 2011
Robert Knox (1791-1862) is typically remembered as the Edinburgh anatomist to whom the murderers Burke and Hare sold the bodies of their victims. This association brought Knox infamy and damaged his life and career. Before the Burke and Hare scandal, Knox was one of the most famous, original and influential anatomists in Britain. He was also something of a dandy with a sophisticated appreciation of the visual arts. His most significant writings on artistic subjects were his books A Manual of Artistic Anatomy and Great Artists and Great Anatomists: A Biographical and Philosophical Study. Knox's interesting and independently minded opinions on the central artistic questions of his day were taken seriously by his contemporaries. His demotion in the official history of anatomy following his involvement with Burke and Hare, however, also removed him from the history of art theory in 19th century Britain. Knox was such a magnetic and impressive figure, though, that he has to be brought back to his era and his era is not complete without him. This paper discusses how Knox's writings on anatomy and biology shaped his contributions to art theory. It is a first step towards returning Knox, the art theorist, to the cultural life of 19th century Britain.
Svec M.,Dawson College
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
Unitary evolution law describes isolated particle scattering processes in an empty Minkowski spacetime. We put forward a hypothesis that the physical Universe includes a quantum environment that interacts with some particle scattering and decay processes. While the scattering process is governed by the S-matrix dynamics and its conservation laws and unitarity, the interaction with the environment evolves the produced final state ρf(S) to the observed state ρf(O). To be consistent with the Standard Model this new interaction must be a pure dephasing interaction. Governed by a nonunitary evolution law, it modifies the phases of the S-matrix amplitudes and can give rise to mixing of such amplitudes to form observed amplitudes. We present the first test of unitary evolution law in particle scattering. Conservation of P-parity in strong interactions imposes constraints on partial wave helicity and nucleon transversity amplitudes in πN→ππN processes. An independent set of constraints on these amplitudes is imposed by the S-matrix unitary evolution law. The unitary evolution evolves pure initial states into pure final states leading to 9 independent constraints on 16 components of angular intensities in πN→ππN processes. When expressed in terms of parity conserving transversity amplitudes, all 9 constraints are identities provided a single constraint on the transversity amplitudes holds true. The constraint implies that relative phases between transversity amplitudes of the same naturality and transversity must be 0 or ±π. Assuming a self-consistent set of these unitary phases we use the CERN data on spin observables Ru0 and Ry0 to determine a unique solution for the S- and P-wave moduli below 1080 MeV. The data require ρ0(770)-f0(980) mixing in the S-wave but this unitary solution is excluded by data on observables Rx0 within at least 5 standard deviations. All previous amplitude analyses of πN→ππN processes found nonunitary relative phases in an apparent violation of the unitary evolution law. The contrast between the predicted unitary relative phases and the observed nonunitary phases presents unambiguous evidence for the nonunitary evolution of the produced final state and supports the hypothesis of the existence of a quantum environment and its pure dephasing interaction with particle scattering processes. © 2015 American Physical Society.
Ganguli A.,Dawson College
Journal of International Trade and Economic Development | Year: 2013
Motivated by the debate in the trade liberalization and the environment literature, this article examines the effect of enhancing green productivity (GP) on bilateral trade flows. The uptake of per capita ISO14001 certification counts is used to measure GP. The existing literature provides other key determinants of bilateral trade flows. This article employs an augmented gravity model and presents panel data analysis on 26 countries from 1995-2004. Since GP is closely related to quality management, this article also examines the joint effect of the measure of quality management systems (QMS) and the measure of GP. Several fixed effects regression equations are estimated. The results support the hypothesis that enhancing green productivity is a positive and statistically significant determinant of real bilateral exports. The joint significance of the measures of GP and QMS is also supported. This article lends empirical support for the new trade theory and Linder's hypothesis and is consistent with those obtained in the existing literature. © 2013 Copyright Taylor and Francis Group, LLC.
Neher A.,Dawson College
Social History of Medicine | Year: 2015
William Clift (1775-1849) was John Hunter's last assistant and six years after Hunter's death he became the first conservator of the Hunterian Museum of the Royal College of Surgeons of England. It was the conservator's duty to anatomise murderers whohad been sentenced to death and dissection. Clift dutifully fulfilled his role and recorded any medically noteworthy features of the bodies. But he did somethingquite out of the ordinaryandsingularwhenhedrewcarefulandsensitively observed portraits of the freshly executed criminals. The drawings are captivating because of the way in which they occupy a representational space that does not fit within medical illustration, artistic portraiture, socialdocumentary or any other conventional category. This paper explores the characteristics that the sketches have as representations and discusses the reasons that might have been behind their creation. © The Author 2015.
Oukarroum A.,University of Quebec at Montréal |
Polchtchikov S.,University of Quebec at Montréal |
Polchtchikov S.,Dawson College |
Perreault F.,University of Quebec at Montréal |
Popovic R.,University of Quebec at Montréal
Environmental Science and Pollution Research | Year: 2012
Purpose: In this study, the effect of silver nanoparticles (AgNPs) on the photosynthetic performance of two green algae, Chlorella vulgaris and Dunaliella tertiolecta, was investigated at 25°C and 31°C. Methods: To induce AgNPs effect, algal cells were exposed for 24 h to concentrations varying from 0 to 10 mg/L. The polyphasic OJIP fluorescence transient was used to evaluate photosystem II (PSII). Results: We show that growth media and temperature had different effects in AgNPs agglomerates formation and Zeta potential. When temperature conditions change, inhibitory effect of AgNPs also undergoes changes. Increase of temperature induced higher altering effects to PSII quantum yield, primary photosynthetic electron transport, and consequently higher decrease of total photosynthetic performance if compared to AgNPs effect alone. AgNPs has a negative effect on D. tertiolecta compared to C. vulgaris. Conclusion: We conclude that temperature tends to enhance the toxic effects on aquatic alga and these alterations might have serious consequences on ecosystem equilibrium and aquatic plant communities. © 2011 Springer-Verlag.
Pearce G.,University of Western Ontario |
Osinski G.R.,University of Western Ontario |
Soare R.J.,Dawson College
Icarus | Year: 2011
We describe and interpret a series of previously unidentified glacial-like lobes (34-43°N; 107-125°E) that were discovered as part of a survey of large (D> 5. km) impact craters in Utopia Planitia, one of the great northern plains of Mars. The lobes have characteristics that are consistent with a glacial origin. Evidence includes curvilinearity of form, lineations and ridges, and surface textures that are thought to form by the sublimation of near-surface volatiles. The lobes display morphologies that range from wedge-shaped to near-circular to elongate. The flow directions are towards the northern walls in the case of craters with large single lobes, and in all directions in the case of the largest (D> 30. km) craters. Concentric crater fill is also interspersed within craters of our study region, with such craters having much higher filling rates than those with flow lobes. We suggest that the impact crater population in south-west Utopia Planitia demonstrates a spectrum of glacial modifications, from low levels of filling in the case of craters with elongate lobes at one extreme, to concentric crater fill in highly-filled craters at the other. © 2010 Elsevier Inc.