9 resultados para Infinite dilution

em Brock University, Canada


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This thesis seeks to elucidate a motif common to the work both of Jean-Paul Sartre and Alain Badiou (with special attention being given to Being and Nothingness and Being and Event respectively): the thesis that the subject 's existence precedes and determines its essence. To this end, the author aims to explicate the structural invariances, common to both philosophies, that allow this thesis to take shape. Their explication requires the construction of an overarching conceptual framework within which it may be possible to embed both the phenomenological ontology elaborated in Being and Event and the mathematical ontology outlined in Being and Event. Within this framework, whose axial concept is that of multiplicity, the precedence of essence by existence becomes intelligible in terms of a priority of extensional over intensional determination. A series of familiar existentialist concepts are reconstructed on this basis, such as lack and value, and these are set to work in the task of fleshing out the more or less skeletal theory of the subject presented in Being and Event.

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An efficient way of synthesizing the deuterium labelled analogues of three methoxypyrazine compounds: 2-d3-methoxy-3-isopropylpyrazine, 2-d3-methoxy-3- isobutylpyrazine, and 2-d3-methoxy-3-secbutylpyrazine, has been developed. To confirm that the deuterium labels had been incorporated into the expected positions in the molecules synthesized, the relevant characterization by NMR, HRMS and GC/MS analysis was conducted. Another part of this work involved quantitative determination of methoxypyrazines in water and wines. Solid-phase extraction (SPE) proved to be a suitable means for the sample separation and concentration prior to GC/MS analysis.Such factors as the presence of ethanol, salt, and acid have been investigated which can influence the recovery by SPE for the pyrazines from the water matrix. Significantly, in this work comparatively simple fractional distillation was attempted to replace the conventional steam distillation for pre-concentrating a sample with a relatively large volume prior to SPE. Finally, a real wine sample spiked with the relevant isotope-labelled methoxypyrazines was quantitatively analyzed, revealing that the wine with 10 beetles per litre contained 138 ppt of 2-methoxy-3-isopropylpyrazine. Interestingly, we have also found that 2-methoxy-3-secbutylpyrazine exhibits an extremely low detection limit in GC/MS analysis compared with the detection limit of the other two methoxypyrazines: 2- methoxy-3-isopropylpyrazine and 2-methoxy-3-isobutylpyrazine.

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The effects of magnetic dilution and applied pressure on frustrated spinels GeNi2O4, GeCo2O4, and NiAl2O4 are reported. Dilution was achieved by substitution of Mg2+ in place of magnetically active Co2+ and Ni2+ ions. Large values of the percolation thresholds were found in GeNi(2-x)MgxO4. Specifically, pc1 = 0.74 and pc2 = 0.65 in the sub-networks associated with the triangular and kagome planes, respectively. This anomalous behaviour may be explained by the kagome and triangular planes behaving as coupled networks, also know as a network of networks. In simulations of coupled lattices that form a network of networks, similar anomalous percolation threshold values have been found. In addition, at dilution levels above x=0.30, there is a T^2 dependency in the magnetic heat capacity which may indicate two dimensional spin glass behaviour. Applied pressures in the range of 0 GPa to 1.2 GPa yield a slight decrease in ordering temperature for both the kagome and triangular planes. In GeCo(2-x)MgxO4, the long range magnetic order is more robust with a percolation threshold of pc=0.448. Similar to diluted nickel germanate, at low temperatures, a T^2 magnetic heat capacity contribution is present which indicates a shift from a 3D ordered state to a 2D spin glass state in the presence of increased dilution. Dynamic magnetic susceptibility data indicate a change from canonical spin glass to a cluster glass behaviour. In addition, there is a non-linear increase in ordering temperature with applied pressure in the range P = 0 to 1.0 GPa. A spin glass ground state was observed in Ni(1-x)MgxAl2O4 for (x=0 to 0.375). Analysis of dynamic magnetic susceptibility data yield a characteristic time of tau* = 1.0x10^(-13) s, which is indicative of canonical spin glass behaviour. This is further corroborated by the linear behaviour of the magnetic specific heat contribution. However, the increasing frequency dependence of the freezing temperature suggests a trend towards spin cluster glass formation.

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This investigation of geochemistry and mineralogy of heavy metals in fine grained (<63^m) sediment of the Welland River was imdertaken to: 1) describe metal dispersion patterns relative to a source, identify minerals forming and existing at the outfall region and relate sediment particle size to chemistry; 2) to delineate sample handling, preparation and evaluate, modify and develop analytical methods for heavy metal analysis of complex environmental samples. Ajoint project between Brock University and Geoscience Laboratories was initiated to test a contaminated site of the Welland River at the base of Atlas Speciality Steels Co. Methods were developed and utilized for particle size separation and two acid extraction techniques: 1) Partial extraction; 2) Total extraction. The mineralogical assessment identified calcite, dolomite, quartz and clays. These minerals are typical of the carbonate-shale rock basement of the Niagara Peninsula. Minerals such as, mullite and ferrocolumbite were found at the outfall region. These are not typical of the local geology and are generally associated with industrial pollutants. Partial and total extraction techniques were used to characterize the sediments based on chemical distribution, elemental behaviour and analytical differences. The majority of elements were lower in concentration in the partial extraction technique; suggesting these elements are bound in an acid extractable phase (exchangeable, organic and carbonate phases). The total extraction technique yielded higher elemental concentrations taking difficult oxides and silicates into solution. Geochemical analyses of grain size separates revealed that heavy metal (Co, Ni, V, Mn, Fe, Ba) concentrations did not increase with decreasing grain size. This is a function of the anthropogenic mill scale input into the river. The background elements (Sc, Y, Sr, Mg, Al and Ti) showed an increase in concentration to the finest grain size suggesting that it is directly related to the local mineralogy and geology. Dispersion patterns ofmetals fall into two distinct categories: 1) the heavy metals (Co, Cu, Ni, Zn, V and Cr), and 2) the background elements (Be, Sc, Y, Sr, Al and Ti). The heavy metals show a marked increase in the outfall region, while the background elements show a significant decrease at the outfall. This pattern is attributed to a "dilution effect" ofthe natural sediments by the anthropogenic mill scale sediments. Multivariant statistical analysis and correlation coefficient matrix results clearly support these results and conclusions. These results indicate the outfall region ofthe Welland River is highly contaminated with to heavy metals from the industrialized area of Welland. A short distance downstream, the metal concentrations return to baseline geochemical levels. It appears, contaminants rapidly come out of suspension and are deposited in close proximity to the source. Therefore, it is likely that dredging the sediment from the river may cause resuspension of contaminated sediments, but may not distribute the sediment as far as initially anticipated.

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Introduction In Difference and Repetition, Deleuze compares and contrasts Kierkegaard's and Nietzsche's ideas of repetition. He argues that neither of them really give a representation of repetition. Repetition for them is a sort of selective task: the way in which they determine what is ethical and eternal. With Nietzsche, it is a theater of un belie f. ..... Nietzsche's leading idea is to found the repetition in the etemal return at once on the death of God and the dissolution of the self But it is a quite different alliance in the theater of faith: Kierkegaard dreams of alliance between a God and a self rediscovered. I Repetition plays a theatrical role in their thinking. It allows them to dramatically stage the interplay of various personnae. Deleuze does give a positive account ofKierkegaard's "repetition"; however, he does not think that Kierkegaard works out a philosophical model, or a representation of what repetition is. It is true that in the book Repetition, Constantin Constantius does not clearly and fully work out the concept of repetition, but in Sickness Unto Death, Kierkegaard gives a full explanation of the self and its temporality which can be connected with repetition. When Sickness Unto Death is interpreted according to key passages from Repetition and The Concept of Anxiety, a clear philosophical concept of repetition can be established. In my opinion, Kierkegaard's philosophy is about the task of becoming a self, and I will be attempting to show that he does have a model of the temporality of self-becoming. In Sickness Unto Death, Kierkegaard explains his notions of despair with reference to sin, self, self-becoming, faith, and repetition. Despair is a sickness of the spirit, of the self, and accordingly can take three forms: in despair not to be conscious of having a self (not despair in the strict sense); in despair not to will to be oneself; in despair to will to be oneself2 In relation to this definition, he defines a self as "a relation that relates itself to itself and in relating itself to itself relates to another.''3 Thus, a person is a threefold relationship, and any break in that relationship is despair. Despair takes three forms corresponding to the three aspects of a self s relation to itself Kierkegaard says that a selfis like a house with a basement, a first floor, and a second floor.4 This model of the house, and the concept of the stages on life's way that it illustrates, is central to Kierkegaard's philosophy. This thesis will show how he unpacks this model in many of his writings with different concepts being developed in different texts. His method is to work with the same model in different ways throughout his authorship. He assigns many of the texts to different pseudonyms, but in this thesis we will treat the model and the related concepts as being Kierkegaard's and not only the pseudonyms. This is justified as our thesis will show this modelremains the same throughout Kierkegaard's work, though it is treated in different ways by different pseudonyms. According to Kierkegaard, many people live in only the basement for their entire lives, that is, as aesthetes ("in despair not to be conscious of having a self'). They live in despair of not being conscious of having a self They live in a merely horizontal relation. They want to get what they desire. When they go to the first floor, so to speak, they reflect on themselves and only then do they begin to get a self In this stage, one acquires an ideology of the required and overcomes the strict commands of the desired. The ethical is primarily an obedience to the required whereas the aesthetic is an obedience to desire. In his work Fear and Trembling (Copenhagen: 1843), Johannes de Silentio makes several observations concerning this point. In this book, the author several times allows the desired ideality of esthetics to be shipwrecked on the required ideality of ethics, in order through these collisions to bring to light the religious ideality as the ideality that precisely is the ideality of actuality, and therefore just as desirable as that of esthetics and not as impossible as the ideality of ethics. This is accomplished in such a way that the religious ideality breaks forth in the dialectical leap and in the positive mood - "Behold all things have become new" as well as in the negative mood that is the passion of the absurd to which the concept "repetition" corresponds.s Here one begins to become responsible because one seeks the required ideality; however, the required ideality and the desired ideality become inadequate to the ethical individual. Neither of them satisfy him ("in despair not to will to be oneself'). Then he moves up to the second floor: that is, the mystical region, or the sphere of religiousness (A) ("despair to will to be oneself). Kiericegaard's model of a house, which is connected with the above definition ofdespair, shows us how the self arises through these various stages, and shows the stages of despair as well. On the second floor, we become mystics, or Knights of Infinite Resignation. We are still in despair because we despair ofthe basement and the first floor, however, we can be fiill, free persons only ifwe live on all the floors at the same time. This is a sort of paradoxical fourth stage consisting of all three floors; this is the sphere of true religiousness (religiousness (B)). It is distinguished from religiousness (A) because we can go back and live on all the floors. It is not that there are four floors, but in the fourth stage, we live paradoxically on three at once. Kierkegaard uses this house analogy in order to explain how we become a self through these stages, and to show the various stages of despair. Consequently, I will be explaining self-becoming in relation to despair. It will also be necessary to explain it in relation to faith, for faith is precisely the overcoming of despair. After explaining the becoming of the self in relation to despair and faith, I will then explain its temporality and thereby its repetition. What Kierkegaard calls a formula, Deleuze calls a representation. Unfortunately, Deleuze does not acknowledge Kierkegaard's formula for repetition. As we shall see, Kierkegaard clearly gives a formula for despair, faith, and selfbecoming. When viewed properly, these formulae yield a formula for repetition because when one hasfaith, the basement, firstfloor, and secondfloor become new as one becomes oneself The self is not bound in the eternity ofthe first floor (ethical) or the temporality of the basement (aesthete). I shall now examine the two forms of conscious despair in such a way as to point out also a rise in the consciousness of the nature of despair and in the consciousness that one's state is despair, or, what amounts to the same thing and is the salient point, a rise in the consciousness of the self The opposite to being in despair is to have faith. Therefore, the formula set forth above, which describes a state in which there is not despair at all, is entirely correct, and this formula is also the formula for faMi in ^elating itself to itself and in willing to be itself, the self rests transparently in the power that established it.

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Investigations of 2-alkyl-3-methoxypyrazines (2-isopropyl-3-methoxypyra2ine, 2- secbutyl-3-methoxypyrazine and 2-isobutyl-3-niethoxypyrazine) in ladybug species {Coleoptera: Coccinellidae) and wine samples have been conducted. Headspace sampling coupled with gas chromatography-mass spectrometry was used to determine amounts of 2-alkyl-3-methoxypyra2ines in the ladybug species. Hippodamia convergens had the highest amount of alkybnethoxypyrazines, followed by Harmoma axyridis and the least in Coccinella septempunctata. Using a solvent extraction method, the precoccinelline alkaloid was found present in Hippodamia convergens and Coccinella septempunctata but not Harmonia axyridis. Steam distillation followed by a soHd phase extraction method as a sample preparation technique, enhanced detection while the isotope dilution method afforded accurate quantitation of the alkyknethoxypyrazines in the wine samples. Both ladybug-tainted and commercial wine samples were found to contain the 2- alkyl-3-methoxypyrazines. Wine samples prepared in 2001 generally contained higher levels than the corresponding 2003 samples. Levels of the 2-alkyl-3-methoxypyrazines found in the commercial wines ranged from a minimum value of 6 ng/L to 260 ±10 ng/L. Analyses revealed that for both ladybug species and wine samples, the 2- isopropyl-3-methoxypyrazine had the highest concentration, followed by 2-isobutyl- 3-methoxypyrazine and the least being the 2-secbutyl-3-methoxypyrazine. Possible contamination of the wine samples by ladybugs is thoroughly discussed. Furthermore, attempts to remove or reduce the levels of the alkylmethoxypyrazines with molecularly imprinted polymers from wine samples are presented in detail.

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The construction of adenovirus vectors for cloning and foreign gene expression requires packaging cell lines that can complement missing viral functions caused by sequence deletions and/or replacement with foreign DNA sequences. In this study, packaging cell lines were designed to provide in trans the missing bovine adenovirus functions, so that recombinant viruses could be generated. Fetal bovine kidney and lUng cells, acquired at the trimester term from a pregnant cow, were tranfected with both digested wild type BAV2 genomic DNA and pCMV-EI. The plasmid pCMV-EI was specifically constructed to express El of BAV2 under the control of the cytomegalovirus enhancer/promoter (CMV). Selection for "true" transformants by continuous passaging showed no success in isolating immortalised cells, since the cells underwent crisis resulting in complete cell death. Moreover, selection for G418 resistance, using the same cells, also did not result in the isolation of an immortalised cell line and the same culture-collapse event was observed. The lack of success in establishing an immortalised cell line from fetal tissue prompted us to transfect a pre-established cell line. We began by transfecting MDBK (Mardin-Dardy bovine kidney) cells with pCMV-El-neo, which contain the bacterial selectable marker neo gene. A series of MDBK-derived cell lines, that constitutively express bovine adenoviral (BAV) early region 1 (El), were then isolated. Cells selected for resistance to the drug G418 were isolated collectively for full characterisation to assess their suitability as packaging cell lines. Individual colonies were isolated by limiting dilution and further tested for El expression and efficiency of DNA uptake. Two cell lines, L-23 and L-24, out of 48 generated foci tested positive for £1 expression using Northern Blot analysis. DNA uptake studies, using both lipofectamine and calcium phosphate methods, were performed to compare these cells, their parental MDBK cells, 8 and the unrelated human 293 cells as a benchmark. The results revealed that the new MDBKderived clones were no more efficient than MDBK cells in the transient expression of transfected DNA and that they were inferior to 293 cells, when using lacZ as the reporter gene. In view of the inherently poor transfection efficiency of MDBK cells and their derivatives, a number of other bovine cells were investigated for their potential as packaging cells. The cell line CCL40 was chosen for its high efficiency in DNA uptake and subsequently transfected with the plasmid vector pCMV El-neo. By selection with the drug G418, two cell lines were isolated, ProCell 1 and ProCell 2. These cell lines were tested for El expression, permissivity to BAV2 and DNA uptake efficiency, revealing a DNA uptake efficiency of 37 % , comparable to that of CCL40. Attempts to rescue BAV2 mutants carrying the lacZ gene in place of £1 or £3 were carried out by co-transfecting wild type viral DNA with either the plasmid pdlElE-Z (which contains BAV2 sequences from 0% to 40.4% with the lacZ gene in place of the £1 region from 1.1% to 8.25%) or with the plasmid pdlE3-5-Z (which contains BAV2 sequences from 64.8% to 100% with the lacZ gene in place of the E3 region from 75.8% to 81.4%). These cotransfections did not result in the generation of a viral mutant. The lack of mutant generation was thought to be caused by the relative inefficiency ofDNA uptake. Consequently, cosBAV2, a cosmid vector carrying the BAV2 genome, was modified to carry the neo reporter gene in place of the £3 region from 75.8% to 81.4%. The use of a single cosmid vector earring the whole genome would eliminate the need for homologous recombination in order to generate a viral vector. Unfortunately, the transfection of cosBAV2- neo also did not result in the generation of a viral mutant. This may have been caused by the size of the £3 deletion, where excess sequences that are essential to the virus' survival might have been deleted. As an extension to this study, the spontaneous E3 deletion, accidently discovered in our viral stock, could be used as site of foreign gene insertion.

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The ease of production and manipulation has made plasmid DNA a prime target for its use in gene transfer technologies such as gene therapy and DNA vaccines. The major drawback of plasmid however is its stability within mammalian cells. Plasmid DNA is usually lost by cellular mechanisms or as a result of mitosis by simple dilution. This study set out to search for mammalian genomic DNA sequences that would enhance the stability of plasmid DNA in mammalian cells.Creating a plasmid based genomic DNA library, we were able to screen the human genome by transfecting the library into Human Embryonic Kidney (HEK 293) Cells. Cells that contained plasmid DNA were selected, using G418 for 14 days. The resulting population was then screened for the presence of biologically active plasmid DNA using the process of transformation as a detector.A commercially available plasmid DNA isolation kit was modified to extract plasmid DNA from mammalian cells. The standardized protocol had a detection limit of -0.6 plasmids per cell in one million cells. This allowed for the detection of 45 plasmids that were maintained for 32 days in the HEK 293 cells. Sequencing of selected inserts revealed a significantly higher thymine content in comparison to the human genome. Sequences with high A/T content have been associated with Scaffold/Matrix Attachment Region (S/MAR) sequences in mammalian cells. Therefore, association with the nuclear matrix might be required for the stability of plasmids in mammalian cells.

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Methoxypyrazines are aroma active compounds found in many wine varietals. These compounds can be of either grape-derived nature or can be introduced into wines via Coccinellidae beetles. Regardless of their origin, methoxypyrazines can have either a beneficial role for wine quality, contributing to the specificity of certain wine varietals (Cabernet sauvignon, Cabernet franc, Sauvignon blanc) or a detrimental role, particularly at higher concentrations, resulting in overpowering green, unripe and herbaceous notes. When methoxypyrazines of exogenous nature are responsible for these unpleasant characteristics, wines are considered to be affected by what is generally known as Ladybug taint (LBT). This is work is a collection of studies seeking to create a sensitive analytical method for the detection and quantification of methoxypyrazines in wines; to investigate the role of different Coccinellidae species in the tainting of wines with LBT and identify the main compounds in ladybug tainted wines responsible for the typical green herbaceous characteristics; to determine the human detection threshold of 2,5-dimethyl-3-methoxypyrazine in wines as well as investigate its contribution to the aroma of wines; and finally to survey methoxypyrazine concentrations in a large set of wines from around the world. In the first study, an analytical method for the detection and quantitation of methoxypyrazines in wines was created and validated. The method employs multidimensional Gas Chromatography coupled with Mass Spectrometry to detect four different methoxypyrazines (2,5-dimethyl-3-methoxypyrazine, isobutyl methoxypyrazine, secbutyl methoxypyrazine and isopropyl methoxypyrazines) in wine. The low limits of detection for the compounds of interest, improved separation and isolation capabilities, good validation data, as well as the ease of use recommend this method as a good alternative to the existing analytical methods for methoxypyrazine detection in wine. In the second study the capacity of two Coccinellidae species, found in many wine regions – Harmonia axyridis and Coccinella septempunctata - to taint wines is evaluated. Coccinella septempunctata is shown to be as capable as causing LBT in wines as Harmonia axyridis. Dimethyl methoxypyrazine, previously thought to be of exogenous nature only (from Coccinellidae haemolymph), is also detected in control (untainted) wines. The main odor active compounds in LBT wines are investigated through Aroma Extract Dilution Assay. These compounds are identified as isopropyl methoxypyrazine, sec- and iso- butyl methoxypyrazine. In the third study, the human detection threshold for dimethyl methoxypyrazine in wine is established to be 31 ng/L in the orthonasal modality and 70 ng/L retronasally. After wines spiked with various amounts of dimethyl methoxypyrazine are evaluated sensorally, dimethyl methoxypyrazine causes significant detrimental effects to wine aroma at a concentration of 120 ng/L. The final study examines methoxypyrazine (dimethyl methoxypyrazine, isopropyl methoxypyrazine, secbutyl methoxypyrazine and isobutyl methoxypyrazine) concentrations in 187 wines from around the world. Dimethyl methoxypyrazine is detected in the majority of the red wines tested. Data are interpreted through statistical analyses. A new measure for predicting greenness/herbaceousness in wines - methoxypyrazine “total impact factor” is proposed.