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Metal complexes containing non-innocent ligands for functional materialsReinhardt, Maxwell James January 2013 (has links)
The existence of complexes of that display non-innocence has been of interest in the field of coordination chemistry since the investigations of square-planar dithiolene complexes of the late transition metals in the 1960s. The ligands used in these systems are termed “non-innocent” when bound to a number of the late transition metals, because the orbital energy levels are similar to those of the central metal ion. This allows there to be significant electron delocalisation over the complex with the potential for the complexes to exist in a number of electronic states due to the combined electrochemical activity. In 1966, Jørgensen classified innocence as ligands that “allow oxidation states of the central atoms to be defined”, thus by this logic non-innocent ligands are defined as complexes where the precise oxidation states of the ligand and metal are ambiguously assigned. However it should be noted that no ligand is inherently non-innocent, but rather the ligand may behave in a non-innocent manner under the right circumstances. The qualification of non-innocence should therefore only be applied to combinations of metal and ligand that result in the aforementioned properties. In this thesis, the term “non-innocent” will be used to define ligands that often possess non-innocent behaviour when complexed to the metal centres they are bound to. A general form of ligand that displays non-innocent behaviour is that of the 1,2-bidentate moiety with an unsaturated carbon backbone. The chelating donor groups (X) are either O, NH, S, or a combination of the three. The central transition metal is generally a late metal that favours a square-planar geometry, because the planarity of the complex is crucial for electron delocalisation within the molecule and molecular interactions in the solid material. When the metal is nickel or platinum for example, their square-planar complexes with such ligands have shown threemembered electron-transfer series. Specific examples of ligands that have been shown to display non-innocent behaviour are those of catechol (1,2-dihydroxybenzene) and 1,2-diaminobenzene, where the unsaturated backbone is provided by a phenyl group. The electronic nature of these compounds has been extensively investigated by the groups of Pierpont and Lever, with focus on their redox and magnetic properties. The combined metal and ligand redox activity results in interesting magnetic behaviour, with potential for magnetic exchange interactions between a paramagnetic metal centre and the radical ligand or between two radical ligands mediated by a diamagnetic metal centre. This research has been advanced by Wieghardt and co-workers who have performed experimental and theoretical examination of non-innocent complexes of 1,2-substituted phenyl chelates, where the donor group is a combination of O and NH. These studies have focused on the understanding the nature of the metal-ligand interactions to apply to biological systems, such as those observed at the active site of enzymes that act upon molecules with similar moieties to the non-innocent ligands. Compounds of catechol may be referred to as dioxolenes in analogy to the sulfur-based dithiolenes. The deprotonated, dianionic form of catechol is known as catecholate (cat), which can be readily oxidised to the monoanionic o-semiquinone (SQ) and neutral o-benzoquinone (Q) forms. It has been seen that catecholate compounds can be described by localised electronic states with defined oxidation states, unlike many of the dithiolene class of molecules. However these states can exist in equilibrium with each other when the metal and ligand orbitals are close in energy, with differences in the charge and spin definition in what has been described as “valence tautomerism”. Therefore, although the complexes may not be seen as non-innocent by definition that their oxidation states are not ambiguous, it is still a useful description due to the potential for easily accessible charge states. Metal dithiolene complexes, where the metal is coordinated by one or more ligands with two S-donor atoms linked by a conjugated backbone, are one of the best researched of the non-innocent class of molecules. The square-planar bis-dithiolenes of the late transition metals have interesting magnetic, optical and electrical properties arising from the delocalised nature of the constituent metal and ligand orbitals, which has enabled their use for a wide range of applications such as non-linear optics, transistors and near-infrared switches. Of particular interest is the ability to fine tune the electrical properties to fit the application by changing the substituents on the core dithiolene moiety. For example, Anthopoulos has shown that by lowering the energy of the lowest unoccupied molecular orbital (LUMO), stable n-channel conductivity can be observed in field-effect transistors (FETs). Materials based on square-planar non-innocent complexes have been tested in FETs, and been seen to display field-effect mobilities as high as 10˗2 cm2 V˗1 s˗1 as with Ni bis(o-diiminobenzo-semiquinonate) complexes. Most of these molecules are based on conjugated, chelating ligands such as 1,2-diaminobenzene and the dithiolene class of molecules. Field-effects have also been observed in square-planar Pt complexes, where the conductivity is thought to arise from beneficial Pt-Pt bonds in addition to the π-stacking between molecules. Despite the similarity to the diaminobenzene and dithiolene counterpart, there are no reports of catechol-based materials displaying field-effect properties in the literature. Catechol compounds are well-researched in the field of biological chemistry due to the prevalence of the catechol moiety and enzymes with which it interacts in nature. However they have not been examined far beyond their simple coordination chemistry or chemical characterisation.
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A seascape genetics approach to exploring the phylogeographic response of marine fishes to late Quaternary climate changeSbrocco, Elizabeth Jones January 2012 (has links)
Thesis (Ph.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / Whether a species will flourish or face extinction under a new climate regime is largely determined by its dispersal ability, its adaptive capacity or some combination of these processes. These processes have also played important roles in the evolutionary histories of species, ultimately shaping their contemporary distributions. In terrestrial studies, a landscape genetics approach is often used to explain how geographic, ecological and evolutionary processes interact to structure spatial genetic variation across populations, but these approaches have only begun to be used in marine ecosystems. This dissertation fills an emerging niche in marine ecology by taking an interdisciplinary seascape genetics approach to investigating the interplay of climate, dispersal and adaptation as shallow-water marine fishes respond to environmental heterogeneity over space and climatological shifts over time. [TRUNCATED] / 2031-01-02
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Les écrits tardifs de Mark Twain : un corpus illisible ? / Mark Twain’s later writings : An unreadable body of works ?Tromp, Alicia 05 November 2016 (has links)
Depuis plusieurs décennies, la critique américaine bouscule les limites traditionnelles du concept de « canon ». Les « grands » auteurs n’ont pas pour autant été congédiés et la notion de canon continue à jouer un rôle central. Ce phénomène double est particulièrement frappant chez Mark Twain. Le corpus illustrant le mieux ce mélange d’hypercanonicité et d’obscurité totale est sans doute celui qui regroupe les textes composés après l’œuvre twainienne canonique par excellence, les célèbres Adventures of Huckleberry Finn : le Twain tardif. Si ces textes sont de plus en plus lus, l’effort d’analyse critique achoppe presque invariablement sur une problématique revenante : celle de leur marginalité ou plus spécifiquement encore, de leur illisibilité. Cette thèse interroge la notion d’illisibilité en conjonction avec la question de la « tardiveté » de ces écrits.L’illisibilité du corpus twainien tardif commence dès l’époque de la rédaction de ces écrits, par une illisibilité dans son acception la plus matérielle et littérale. Cette illisibilité s’accompagnait d’entrée de jeu d’un autre type d’illisibilité, fondé sur le jugement et l’appréciation esthétiques (des textes illisibles car mal écrits). Cette thèse cherche à lire l’illisible, sans pour autant chercher à réhabiliter le corpus, sans même entreprendre de confirmer l’existence pleine de l’objet d’étude choisi, de ce corpus tardif en tant qu’ensemble de textes unifiables à l’intérieur d'une catégorie chronologique close et évidente. Loin d’ignorer l’ennui, l’exaspération et la déception que ces textes ont pu inspirer, il s’agit de problématiser la notion d'illisible. / Although deconstructed and challenged, the idea of the literary canon seemsto have survived. This ambiguous phenomenon has affected approaches to Mark Twain’swork to a profound degree. The group of texts most aptly illustrating this odd interlacingof hypercanonicity and complete obscurity is that which follows Huckleberry Finn : thelater writings of Twain. These texts invariably call up the question of their marginalityand their unreadability. Why were they left unread for so many years, and why do theycontinue to be so marginal, when compared to the immense success of the Adventures ?Can some of the manuscripts be salvaged by means of certain literary approaches and atspecific times in the history of aesthetic moods ? This PhD on Twain’s later writingsaims to explore the idea of unreadability by combining it with theoretical and criticalaccounts of lateness. « Unreadability » as a central notion to Twain’s later work startswith the most material and literal meaning of the word – that which cannot be read – andbegan as early as the moment of composition of these texts : many manuscripts remainedunpublished, incomplete, or were rejected by the publishers Twain approached. Thisillegibility combined with the texts’ frequently decried unreadability. The aim of this PhDis to read late Twain without necessarily attempting to rehabilitate these texts, withouteven confirming the full existence of the idea of « late » Twain. Instead of ignoring theexasperation and disappointment many critics and readers have experienced, this thesiswill attempt to work with this unreadability, but not without questioning and redefiningthe notion of unreadability and its contraries.
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RESERVOIR CHARACTERIZATION OF THE KIZLER NORTH FIELD, LYON CO., KANSAS, USAHASAN, MD NAHIDUL 01 August 2019 (has links)
The Kizler North Field is near the western flank of the Forest City Basin in Lyon Co., Kansas, USA and produces oil from the Hunton Formation, Viola Formation and Simpson Group reservoirs. The structure strikes NW through the field that is part of a larger wrench fault system. This modern prospect analysis of the Kizler North Field, aids in understanding the reservoir properties of the Hunton Formation, Viola Formation and Simpson Group rocks, the play mechanism of the field, and provides recommendations for additional drilling locations.
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Zur lokalen Epidemiologie multiresistenter biofilmbildender Staphylococcus epidermidis Stämme bei sehr kleinen Frühgeborenen und ihren Müttern / Local epidemiology of multi-resistant biofilm forming Staphylococcus epidermidis strains in very low birth weight infants and their mothersGellichsheimer, Eva January 2012 (has links) (PDF)
Das grampositive Bakterium Staphylococcus epidermidis ist ein wesentlicher Bestandteil der kommensalen Flora der Haut und der Schleimhäute des Menschen. Jedoch stellen diese Bakterien eine häufige Ursache nosokomialer Katheter-assozierter Infektionen bei immunsupprimierten Patienten dar. Dies liegt zum einen an der Fähigkeit von S. epidermidis, Biofilm zu bilden. Diese physikalische Barriere schützt die Bakterien vor dem Immunsystem sowie vor Antibiotika. Dabei zählen sie zu den häufigsten Erregern von Infektionen an implantierten Fremdkörpern mit Plastikoberflächen, wie z. B. Venenkathetern, künstlichen Herzklappen oder Gefäßprothesen. Zum anderen stellt die Antibiotikaresistenzentwicklung unter S. epidermidis ein zunehmendes Problem dar. Vor allem die late-onset Sepsis, die durch S. epidermidis als Erreger verursacht werden kann, stellt für Frühgeborene eine Gefahr dar. Ziel der vorliegenden Arbeit war, für S. epidermidis als häufigsten und klinisch bedeutsamen KoNS zu eruieren, ob die zunehmende Dauer des stationären Krankenhausaufenthaltes von sehr kleinen Frühgeborenen mit einer höheren Rate an ica-Präsenz, Biofilmbildung und Antibiotikaresistenz assoziiert ist, sowie die Verbreitungswege und das Reservoir für diese S. epidermidis-Stämme zu identifizieren. Hierzu wurden sequenzielle Isolate von S. epidermidis bei Müttern, Kindern und vom Krankenhauspersonal gewonnen und mittels MLST (Multilocus-Sequence-Typing) klonal typisiert. Sie wurden auf Antibiotikaresistenzen, Biofilmbildung und Präsenz des icaA-Gens, das eine Rolle bei der Biofilmbildung spielt, sowie des mecA-Gens untersucht und mit Isolaten, die aus Blutkulturen oder Venenkatheter des Kindes isoliert wurden, verglichen. Es fiel auf, dass die Isolate der sehr kleinen Frühgeborenen deutlich mehr Virulenzfaktoren, wie z.B. Biofilmbildung, hohe Antibiotikaresistenzraten sowie die Präsenz des mecA- und des icaA- Gens, als die maternalen Stämme besaßen. Im Vergleich mit den Ergebnissen der untersuchten Personalstämme liegt der Verdacht nahe, dass oftmals auch das Personal als Transmitter, vor allem von Klonen mit mehreren Virulenzfaktoren, dient. Das Krankenhaus-Milieu scheint dabei ein ideales Reservoir für die Ausbreitung solcher gefährlichen S. epidermidis-Stämme zu sein. / Staphylococcus epidermidis is usually a commensal inhabitant of the human skin and mucosa. However, they are a common cause of nosocomial infections, especially in context with medical devices and catheters in immunocompromised patients. This is due to the ability of Staphylococcus epidermidis to form biofilms on inert surfaces of medical devices, like intravenous catheters or artificial arthroplastics. Furthermore the development of antibiotic resistances among Staphylococcus epidermidis is another problem. Especially the late-onset-sepsis is a danger for very low birth weight premature infants. The aim of the study was to identify for S. epidermidis isolates in very preterm infants, if a longer stay in the hospital is associated with a higher carriage of the ica-operon, a higher antibiotic resistance and the ability to form biofilms. The reservoir and the means of distribution of these nosocomial isolates should be idendified. Therefore sequential isolates were taken from mothers, their children and from the hospital staff. They were clonally typified by MLST (Multilocus-Sequence-Typing) and tested for antibiotic resistances, biofilm formation and the presence of the icaA- and mecA gene. Then they were compared with isolates from blood cultures or venous catheters from the preterm infants. Herby it was remarkable that the isolates of the very premature infants had more virulence factors, e.g. formation of biofilm, antibiotic resistances and the presence of the icaA- and mecA gene, as the maternal isolates. Compared to the results of the isolates from the medical staff it could be suggested that the staff transmits these opportunistic pathogens. The hospital environment seems to be an ideal reservoir for these dangerous S. epidermidis isolates.
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Reconsidering Late Roman Cyprus: Using new material from Nea Paphos to review current artefact typologiesRowe, Andrea Helen January 2005 (has links)
This thesis is based around detailed analysis of an assemblage of newly excavated material from the Paphos Theatre site in SW Cyprus. Before presenting the new work, the academic context into which it must fit is investigated. This process of re-evaluating past work sets up a framework within which the new material would be expected to fit. In fact, research on Late Roman Cyprus is not as advanced as might be expected after over seventy years of excavation. This is most particularly the case for fundamental principles like typology and chronology for the local ceramics and glass. A review of past and current excavations shows that the typology of Cypriot Red Slip ware is widely used around the Eastern Mediterranean as a dating tool for deposits containing this distinctive Fine ware. This makes it essential that it be confirmed to be a reliable and substantially correct construct. Unfortunately, a re-analysis of the foundations of the Cypriot red Slip ware typology and chronology reveals many uncertainties and establishes the necessity for new material from secure deposits to help refine current typologies. The artefact assemblage from Area Three at the Paphos Theatre provides just such an opportunity. A combination of a series of sealed deposits, a high density of artifacts and identifiable coins has enabled a comprehensive study to be achieved. A major collapse, probably an earthquake, sealed a paved street and drainage system in the trenches and this episode can be pinpointed to around the mid to late fifth century by the coin evidence. Most interesting is the fact that the dating suggested by the coins does not match the dating usually assigned to the associated pottery and glass. After establishing the reliability of the coin evidence, the study of the other artefacts offers new ideas about the dating and typology of the local Cypriot Red Slip ware, Cooking ware, Lamps and Glass. In fact an analysis of all the pottery from the site suggests that the chronology of Cypriot Red Slip ware and Cooking ware in particular needs to be pushed back to focus on a floruit in the fourth and fifth centuries. This is at least one hundred years earlier than current typologies that focus on the mid sixth to seventh centuries. This analysis provides some reliable fixed points, for both local pottery and glass, earlier in the Late Roman sequence upon which future work can be built.
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Molecular characterization of 33K protein of bovine adenovirus type 3Kulshreshtha, Vikas 04 March 2009
Bovine adenovirus type 3 (BAdV-3) is a non-enveloped icosahedral particle which contains a double stranded DNA genome. The genome of BAdV-3 is organized into early, intermediate and late regions. The late region is organized into seven regions L1-L7 (Reddy et.al., 1998). The L6 region of late transcription unit of BAdV-3 encodes one of the non structural protein named 33K protein. The objective of the present study was to characterize the 33K protein and to identify the viral/cellular proteins involved in the interaction with 33K protein.<p>
The RT-PCR analysis revealed the presence of spliced and unsliced mRNAs encoding 33K and 22K proteins respectively in BAdV-3 infected cells. The 33K and 22K proteins share a N-terminus region of 138 amino acids. To determine the specificity of these two proteins, rabbit polyclonal antiserum was raised against peptides representing unique C- terminal regions of the proteins. Anti-33Kp serum detected two major proteins of 42 kDa and 22 kDa and five minor proteins of 39kDa, 35kDa, 29kDa, 25kDa and 19kDa in BAdV-3 infected cells or 33K transfected cells. Similarly, anti-22Kp serum detected three proteins of 41kDa, 39kDa and 37kDa in BAdV-3 infected cells. However, a protein of 39kDa and 37kDa was detected in 22K (having splice sites removed) transfected cells. The 33K protein is predominantly localized to the nucleus of BAdV-3 infected cells and is involved in stimulating the transcription from major late promoter. Analysis of mutant 33K proteins demonstrated that amino acids 201-240 and amino acid 204-231 are required for nuclear localization and MLP transactivation.<p>
The adenovirus 33K protein appears to be a multifunctional protein performing different role in viral infection. Earlier study has shown that the 33K protein plays a role in viral capsid assembly and efficient capsid DNA interaction in BAdV-3 (Kulshreshtha et.al., 2004). The involvement of 33K protein in different steps of adenovirus replication may require protein protein interaction. Using 33K protein as bait in yeast two hybrid system, open reading frames (ORFs) of BAdV-3 were screened for the potential interactions with 33K protein. The 33K protein showed specific interactions with two late viral proteins- 100K and protein V (pV). The yeast two hybrid findings were validated by in vitro binding using <i>in vitro</i> synthesized transcription-translation products. It was demonstrated that the interaction of 33K with 100K and pV takes place during BAdV-3 infection. The stretch of amino acids 81-120 and 161-200 in 33K protein were involved in the interaction with pV and 100K protein.<p>
For screening the cellular interactions, the 33K protein was used as a bait to screen bovine retina cDNA library. The yeast two hybrid screening revealed that the 33K protein appears to interact with bovine presenilin-1-associated protein / mitochondrial carrier homolog 1 (BoPSAP / BoMtch1) and bovine microtubule associated protein (BoMAP). However, subsequent analysis by various <i>in vitro</i> and <i>in vivo</i> assays could only confirm the interaction between 33K protein and BoPSAP/BoMtch1. In addition, the 33K protein was also shown to be colocalized with BoPSAP in mitochondria. Based on these observations, it may be possible that 33K protein may play an anti-apoptotic by interacting with BoPSAP since the human homolog of PSAP has been known to induce apoptosis.
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Vickers focus and mortlach-examining cultural connections in the Makotchi-Ded Dontipi localeMokelki, Lorie Lynn 07 June 2007
Many of the pre-contact and early contact cultures of the Northern Plains have been the subjects of debate in archaeological circles. Mortlach and Vickers focus are no exception. One of the issues to date is the possible relationship between these two groups. A key to understanding this relationship lies in the Makotchi-Ded Dontipi locale in Manitobas Lauder Sandhills. This unique ecological island is home to a great number of sites (Hamilton and Nicholson1999), including neighboring Vickers focus and Mortlach sites.<p>This study offers the results of a comprehensive analysis of the pottery assemblages recovered from the Jackson, Vera, Twin Fawns, Schuddemat and Hollow B sites of the Makotchi-Ded Dontipi locale. In addition, it examines the prior cultural affiliation of these sites. Though in many ways different from eastern Vickers focus assemblages, Jackson and Vera assemblages should be considered Vickers focus. Many of the discrepancies are due to the changing nature of the sites over time in conjunction with contact with neighboring Mortlach groups. Schuddemat and Twin Fawns also differ from typical Mortlach assemblages. These differences can be attributed to their location on the eastern periphery of the Mortlach spatial distribution where they came in contact with, and were likely joined by Vickers focus people.<p>Mortlach, Vickers focus and Wascana ware are likely all a part of a larger phenomenon of eastern Woodlands migration onto the Canadian Plains. These cultures became distinct over time through interaction with neighboring groups and exploitation of territorial resource bases. Though distinct, they share a number of similarities reflecting common ancestors. These similarities culminate in the Makotchi-Ded Dontipi locale where interaction between Mortlach and Vickers focus people likely resulted in the amalgamation of Vickers focus into Mortlach. This amalgamation is reflected in the pottery assemblages of Twin Fawns and Schuddemat which seem to represent a Vickers variant of the Lake Midden subphase of Mortlach.
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Shoreline Dynamics and Environmental Change Under the Modern Marine Transgression: St. Catherines Island, GeorgiaMeyer, Brian K. 01 August 2013 (has links)
The current study has evaluated shoreline dynamics and environmental change at St. Catherines Island, Georgia, with attention to the two major controls of barrier island formation and modification processes. These major controls include the increase in accommodation space, or the rate of sea level rise for the Georgia Bight which has remained constant in 20th and 21st century tide gauge data and dynamically changing rates of sediment supply based on anthropogenic modifications to land cover (Trimble, 1974) that are reflected in sediment transport (McCarney-Castle et al., 2010). Vibracoring and radiocarbon data provided valuable insights into the stratigraphy and development of St. Catherines Island. A stratigraphic model has been developed for the sediments associated with the Late Holocene accretional terrains where multiple small scale fluctuations in sea level have resulted in the formation of a sedimentary veneer punctuated with transgressive surfaces and regressive sequences. A working model for an interpolated Late Holocene sea level curve has been constructed using direct evidence from vibracore data as constraining points and indirect evidence from other regional sea level studies to provide additional structure. The relationship between the timing of the regressions versus periods of beach ridge formation and implications from the current shoreline dynamics study regarding the role of sediment supply complement each other. The ages of beach ridge formation strongly correlate to periods that are associated with regressions in sea level based on the sedimentary record and an evaluation of Late Holocene sea level conditions. The evaluation of anthropogenic modifications to the rate of sediment supply performed under the current study indicates that in spite of significant changes in sediment flux rates of +300% (pre-dam era) and -20% (post-dam era), shoreline retreat was continuous during the study period with an acceleration noted in the rates of shoreline retreat associated with spit and berm landforms during the post-dam or modern era. The two associations indicate strongly that the rate of sediment supply plays a secondary role to the major control of the rate of sea level rise in the formation and modification processes at St. Catherines Island.
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Vickers focus and mortlach-examining cultural connections in the Makotchi-Ded Dontipi localeMokelki, Lorie Lynn 07 June 2007 (has links)
Many of the pre-contact and early contact cultures of the Northern Plains have been the subjects of debate in archaeological circles. Mortlach and Vickers focus are no exception. One of the issues to date is the possible relationship between these two groups. A key to understanding this relationship lies in the Makotchi-Ded Dontipi locale in Manitobas Lauder Sandhills. This unique ecological island is home to a great number of sites (Hamilton and Nicholson1999), including neighboring Vickers focus and Mortlach sites.<p>This study offers the results of a comprehensive analysis of the pottery assemblages recovered from the Jackson, Vera, Twin Fawns, Schuddemat and Hollow B sites of the Makotchi-Ded Dontipi locale. In addition, it examines the prior cultural affiliation of these sites. Though in many ways different from eastern Vickers focus assemblages, Jackson and Vera assemblages should be considered Vickers focus. Many of the discrepancies are due to the changing nature of the sites over time in conjunction with contact with neighboring Mortlach groups. Schuddemat and Twin Fawns also differ from typical Mortlach assemblages. These differences can be attributed to their location on the eastern periphery of the Mortlach spatial distribution where they came in contact with, and were likely joined by Vickers focus people.<p>Mortlach, Vickers focus and Wascana ware are likely all a part of a larger phenomenon of eastern Woodlands migration onto the Canadian Plains. These cultures became distinct over time through interaction with neighboring groups and exploitation of territorial resource bases. Though distinct, they share a number of similarities reflecting common ancestors. These similarities culminate in the Makotchi-Ded Dontipi locale where interaction between Mortlach and Vickers focus people likely resulted in the amalgamation of Vickers focus into Mortlach. This amalgamation is reflected in the pottery assemblages of Twin Fawns and Schuddemat which seem to represent a Vickers variant of the Lake Midden subphase of Mortlach.
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