McGill University Thèses et mémoires publiés en 1991

This study focuses on the effects of nominal shocks on the real exchange rate. The model used to determine the effects of a monetary expansion on the real exchange rate assumes instantaneously clearing asset markets and sticky goods prices. A monetary expansion causes the nominal exchange rate to initially overshoot its long run equilibrium value followed by a series of appreciations. The real exchange rate depreciates sharply and then appreciates until its initial value is restored. A simple monetary model, a sticky price monetary model and a random walk model are empirically tested with Canadian/U.S. data over the 1972-1989 time …  Lire la suite

Few rotary blasthole drills presently used in open pit mines are equipped with automatic control systems. Those drilling control systems which do exist are based mainly on ladder programming techniques. This thesis is an investigation into a closed loop feedback control approach for drilling control. A model for the plant consisting of the machine's actuators and the drilling process at the bit-rock interface is described based on physical assumptions and past research in this area. The model equations are further refined by experimental (field) testing. The instrumentation of a TAMROCK-DRILTECH D75K drill rig and the subsequent drilling tests aimed at …  Lire la suite

lck is a member of the src family of tyrosine protein kinase genes expressed predominantly in T-lymphocytes. Its product, p56$ sp{ rm lck}$ is physically and functionally associated with the CD4 and CD8 T-cell surface antigens, suggesting a possible role in CD4/CD8-mediated tyrosine phosphorylation signals during the process of antigen stimulation. Activation of p56$ sp{ rm lck}$ by mutation of tyrosine 505 was prevented by further mutation of either the site of autophosphorylation, tyrosine 394 to phenylalanine, or the site of myristylation, glycine 2 to alanine, as determined by the effects of overexpression of these p56$ sp{ rm lck}$ mutants …  Lire la suite

The basic research question this thesis addresses is how the secondary status of Bangladeshi women is reinforced through household labour. It is argued that gender relations and housework shape each other. To develop this, it examines the degree of participation of women in different areas of housework and family decisions. The thesis further explores whether the autonomy of women coming from the traditional Bangladeshi family set-up has increased as a result of their immigration to Canada and their exposure to Canadian family values. This is done by a comparison of the family experiences of Canadian and Bangladeshi women. Finally, it …  Lire la suite

This thesis describes a search for DNA polymorphisms at the HEXA locus as well as the characterization of three Tay-Sachs disease (TSD) mutations in the Chinese population. No polymorphisms were detected in the HEXA gene by three different methods: (1) Southern blotting; (2) PCR amplification and restriction enzyme digestion of intronic sequences; (3) single strand conformational polymorphism (SSCP) analysis of introns. The apparent deficiency of accessible polymorphisms is a handicap in studying the origin, distribution, and frequency of mutant HEXA alleles in human populations. I have characterized five of six infantile TSD alleles segregating in three unrelated Chinese families in …  Lire la suite

Liquid hog manure (LHM) obtained from the Macdonald College farm was used in experiments aimed at (a) reducing the odor associated with LHM during handling and (b) conserving the fertilizer capacity of LHM. Various chemical treatments and sphagnum moss (SM) were evaluated to achieve the above objectives. Direct acidification to $<$ pH 5.0, sphagnum moss (SM) and its combination with aluminum sulfate (AS) resulted in significant (p $<$ 0.05) reduction in ammonia losses during storage of LHM. The SM and SM/AS combination also significantly (p $<$ 0.05) reduced both odor presence and offensiveness. Gas chromatographic (GC) and GC/mass spectrometry (GC/MS) …  Lire la suite

This study is concerned with the biodegradation of polycyclic aromatic hydrocarbons (PAHs), particularly the utilization of biological processes in the bioremediation of PAH-contaminated soils. In this regard, the effects of the contaminant bioavailability and the redox environment on the biodegradation process have been investigated. First, the mineralization of naphthalene in soil/water systems under denitrifying conditions has been studied. Results showed that naphthalene mineralization is influenced by its availability to the microbial population, which in turn is a function of the compound initial concentration, the sorption/desorption characteristics of the soil/contaminant complex and the organic content of the soil. Second, the biodegradation …  Lire la suite

Paidoussis, Michael P. (Supervisor)  Lire la suite

There seems to be wide acceptance of the idea that divergencies between legal systems give rise to disadvantages. These divergencies are, and have always been, regarded as inconveniences to overcome, particularily between the Civil and Common Law traditions, which present quite diverging points of view in the way the Law is thought. Today, one criterion of evaluating any harmonization of international legal norms is the extent to which the effort enhances certainty, a quality much appreciated in the field of international commercial contracts. In fact, today, there is a detectable effort on the international level to harmonize the laws, especially …  Lire la suite

A technique for combining equalization and differentially coherent detection is proposed for use in wireless communication when carrier phase recovery is difficult. A decision-feedback differentially coherent scheme, which generates an improved reference phase, is combined with a linear equalizer and the LMS algorithm is used to adapt the equalizer to an unknown channel. In addition, the proposed receiver is simulated for various two-dimensional signal constellations over multipath channels. It is shown that for high SNR, the degradation of this structure is negligible with respect to combined coherent detection and equalization. Therefore, this equalized differentially coherent detection scheme can be used …  Lire la suite

This study investigated the effects of an orientation program on the acculturative stress of international students. The sample consisted of 36 international graduate students who were studying at McGill University. An orientation program was designed and implemented using three delivery methods--information giving, support, and a combination of the two. Pre- and posttreatment levels of acculturative stress were statistically analysed to ascertain the effects of this program. The quantitative results lacked statistical significance, but the qualitative analysis of the data indicated the orientation program was beneficial for international students. Participant responses denoted that the combination method was the most effective in …  Lire la suite

Drilling and cutting operations are required in many industrial applications. For example an advanced flexible manufacturing system using robotics technologies may be required to perform such operations. Variation in the mechanical properties of a material to be processed, and compliance add complexity to the already nonlinear robotic system. Thus, these tasks are difficult to perform. For cutting and drilling processes, it is often desirable to maintain a constant cutting force to maintain productivity and also to maintain the quality of the finished workpiece. To counter the effect of the material variations while maintaining a constant cutting force, a controller mechanism …  Lire la suite

Amyloidosis is a chronic degenerative disease that is characterized by the deposition of fibrous $ beta$-pleated amyloid proteins in various soft tissues and organs (Glenner 1980, Kisilevsky 1983 & 1987). Sporadic form of Alzheimer's disease is one of the most common forms of systemic amyloidosis, with the current prevalence of approximately 4 million cases in the United States and 6 to 8 million cases worldwide (Kisilevsky 1987, Coleman 1990). Amyloidosis can be experimentally induced in animals. In the inflammation-associated mouse model of amyloidosis, the preamyloid phase, which usually lasts for a number of weeks, is shortened to 24 to 48 …  Lire la suite

An investigation of copper matte vacuum purification was undertaken. A mathematical model using monatomic, diatomic sulphide and diatomic oxide vapours of the impurities was developed to explain the vacuum refining process. The model was used to predict the overall refining rates for variables such as temperature, matte grade, oxygen activity and chamber pressure of the melt. A series of experiments was undertaken to characterize the dust produced during vacuum refining of copper matte. An attempt to selectively condense the vapours produced during the vacuum refining experiments was carried out. The "Lift-Spray" vacuum refining process was used to refine 15 to …  Lire la suite

The most common and generally best performing replacement algorithm in modern caches is LRU. Despite LRU's superiority, it is still possible that other feasible and implementable replacement policies could yield better performance. (34) found that an optimal replacement policy (OPT) would often have a miss rate 70% that of LRU. If better replacement policies exist, they may not be obvious. One way to find better policies is to study a large number of address traces for common patterns. Such an undertaking involves such a large amount of data, that some automated method of generating and evaluating policies is required. Genetic …  Lire la suite

A relativistic equation, known as the Kemmer-Duffin-Petiau (KDP) equation, for spin-0 particles is used to study low energy pion-nucleus scattering. This equation is linear and the optical potential is completely local in contrast to the quadratic Klein-Gordon equation which contains gradient terms in the p-wave part of the potential when applied to pion-nucleus scattering. Specifically, if we use an almost minimal coupling scheme (scalar and vector potentials), then this equation is equivalent to the Klein-Gordon equation with a Kisslinger potential and an effective Ericson-Ericson-Lorentz-Lorenz parameter $ lambda$ = 3. Experimentally, the $ lambda$ parameter is subject to uncertainty and no …  Lire la suite

That Ghana derives her foreign exchange earnings mainly from cocoa and gold exports cannot be over emphasised. There is therefore the need to forecast these commodities prices as accurately as possible for proper planning and execution of major policies, since the prices have been notoriously volatile during the past two decades and attempts to stabilize especially the price of the beans (which contributes about 60% of the country's foreign exchange) through the system of buffer stock and export restrictions have not been successful. In this regard, autoregressive integrated moving averages models are built and used to generate short run forecasts …  Lire la suite

During the summer 1988 and 1989, surveys were conducted on the muck soils, South of Montreal to estimate the prevalence and incidence of the carrot diseases. Cercospora blight was the most prevalent disease; 91% and 96% of the fields and 99% and 92% of the plants sampled were diseased in 1988 and 1989, respectively. In decreasing order of occurrence the diseases present were: Crown gall, Alternaria blight, Root Knot, Sclerotinia rot and Aster yellows. Greenhouse and field studies were carried out to evaluate partial resistance to Cercospora blight in 111 carrot cultivars based on the mean incubation period (MIP), the …  Lire la suite

The purpose of this research project has been to evaluate the feasibility of improving the impact properties of polypropylene (PP)/ethylene vinyl alcohol copolymer (EVOH) laminar blends by the incorporation of a rubber phase. The impact modifier was poly (ethylene-propylene) rubber (EPR). The study was conducted initially with a batch mixer, and then continued with an extruder. Furthermore, it was decided to evaluate the improvement in impact toughness of the blends upon addition of a polyethylene (PE) phase. The batch mixing studies showed that it is possible to bring the impact properties of maleated PP (MAPP)-based blends to the range of …  Lire la suite

Leaf surface wetness duration time is an important agrometeorological parameter that determines fungal infections and spread of plant diseases. Surface wetness could also contribute to the reduction of transpiration and enhance pesticide effectiveness. For these reasons, field and laboratory performances of commonly used electrical resistance (ER) sensors were compared with a beta-ray gauge (BRG). The BRG provided the most accurate measure of surface wetness duration which agreed favourably with visual observations since it uses a real leaf as a sensor. A commercially available electric grid sensor (Model 237, Campbell Scientific), which employs a hard epoxy-fibreglass board, was found to be …  Lire la suite

This thesis describes a study of novice problem solving in the domain of medicine. The study attempts to answer questions pertaining to the diagnostic accuracy, the generation and change of diagnostic hypotheses, and the use of clinical findings in the course of solving clinical cases with similar presenting complaints. Two specific issues are addressed: (1) how does the initial case presentation suggesting a common disease schema affect the diagnostic problem solving process of novices and intermediate subjects? (2) what are the processes the subjects used in coordinating hypothesis and evidence during diagnostic problem solving? Medical trainees (students and a resident) …  Lire la suite

We study the effective action that governs heterotic string theory compactified on a four-dimensional, N = 1 supersymmetric background. A scaling symmetry of the four-dimensional field T that represents the breathing mode on of internal manifold is introduced. This symmetry, being valid at each order in both perturbative series of the theory (string-loop and sigma model expansions), is used to find restrictions on the terms that can correct the truncated supersymmetric functions entering the effective action. We derive the general form of these corrections and show that, contrary to earlier conjectures in the literature, loops are not a priori counted …  Lire la suite

With the institution of the Moroccan Protectorate by the French in 1912, the military command had as its primary intention that of restoring law and order. Under the strong personality of the "resident general", Lyautey, a new era of "soft" political colonization was introduced in Morocco; brutish military conquests were followed by a certain cooptation process of the Moroccan elite. This association policy allowed the perception of real cooperation between the French and the Moroccans but was actually aimed at the tight regulation of the population. The efficiency of this regulation was achieved through its technocratic approach; it showed respect …  Lire la suite

Microcomputer technology and the provision of alternative data entry devices offers numerous opportunities for physically disabled individuals to integrate into work and school settings. For therapists specializing in adapted access one of the main challenges involves prescribing and customizing suitable input devices since objective procedures to facilitate this process are lacking. The two papers presented in this thesis aimed to respond to this limitation. In the first paper the adapted access process was viewed within the context of a human factors model. A critical review of the literature relating specific human factors criteria (e.g. digit loading) to ergonomic solutions (e.g. …  Lire la suite

The issue of nonresponse to surveys is a serious problem in survey research because it reduces the amount of information obtained, creates a significant nuisance for data analysis and may introduce bias into the survey results by flawing the representativeness of the target population under investigation. This paper examines item-nonresponse and "don't know" responses in the General Social Survey of Canada of 1985 and comments specifically on the different effects of personal and telephone interviewing technique on rate of item omission. The effect of sensitivity of the question, and position of the item in the questionnaire on nonresponse are also …  Lire la suite

A two-length-scale turbulence model is introduced in this thesis for the computation of quasi-two-dimensional turbulent shear flow with two distinct length scales of motion. In the model, the turbulence motions of the two distinct length scales are computed separately. The small-scale turbulence is treated as a background component locally in equilibrium while the large-scale turbulence is simulated using a second-order closure procedure. The development of the turbulent shear flows depends on the rate of energy transfer from the large-scale to the small-scale turbulence. Two mechanisms are identified to have a significant effect on the rate of this energy transfer. On …  Lire la suite

In this work, the carbothermal reduction of Al$ sb2$O$ sb3$ to AlN was studied. Several kinds of aluminum oxides including $ alpha$-Al$ sb2$O$ sb3$, $ gamma$-Al$ sb2$O$ sb3$, $ theta$-Al$ sb2$O$ sb3$ and boehmite (AlOOH) were examined in order to observe the differences in reaction behaviour and powder characteristics obtained from each type of precursor. Cane sugar (sucrose) and carbon black were used as carbon sources. Reaction conditions studied were carbon to alumina ratio, temperature and reaction time. Sucrose resulted in a close-to-stoichiometric ratio of Al$ sb2$O$ sb3$:C (1:3.2) achieving full conversion to AlN and produced a regular powder morphology, …  Lire la suite

Historical evidence has shown that increases in coffee prices, though generating a short term gain in export earnings for producers, also lead to increased plantings of the coffee crop. This in turn leads to overproduction and a subsequent drop in coffee prices. The establishment of the International Coffee Agreements was meant to stabilize this fluctuating behaviour in coffee prices. The purpose of this paper is to present an overall analysis of coffee prices in order to predict the future course of prices under two circumstances. First, when the international coffee market is governed by the mandates of the International Coffee …  Lire la suite

Following and at times reworking the relation between language, society and selfhood in the antifoundationalist philosophies of Charles Taylor and Richard Rorty, the thesis develops the idea of the novel as a kind of conversation. The thesis takes James Joyce's Ulysses as a progression of thought and style in which its three principal characters, Stephen Dedalus, Leopold Bloom and Molly Bloom, expound their views and then lapse into silence as part of an ongoing conversation. Three episodic conversations in particular are discussed: for Stephen, Scylla and Charybdis; for Bloom, Cyclops; and for Molly, Penelope. These conversations, it is suggested, parallel …  Lire la suite

This thesis attempts to analyse both the characteristics and the presuppositions that constitute the writing of the philosopher and literary critic, Jacques Derrida. More concretely, this analysis proposes to bring out the principal factors that illustrate the form of writing and thought in Glas. Glas is a real laboratory where Derrida plays with the "text" and the broken form of thought. Derrida proves that the broken form of writing can neither achieve the status of oeuvre nor protect its own literary nature.  Lire la suite

Rheological behavior of two commercial brands of stirred yogurt were investigated using a Haake RV 20 rotational viscometer. For samples from both brands, the upward shear-rate flow behavior generally followed the Herschel-Bulkley model and the downward flow curves were linear. They demonstrated progressive structural degradation with repeated shearing. In the steady shear runs, all samples exhibited apparent thixotropic behavior and did not attain the equilibrium condition even after 60 min of continuous shearing. The time-dependent stress decay behavior of all samples were accurately described by Weltman's logarithmic time model. The rheological properties of both yogurt brands were qualitatively similar. Both …  Lire la suite

A study was conducted to measure pesticide concentrations from two tile-drained potato fields in Saint-Leonard d'Aston, Quebec. Soil and water samples were analysed for the pesticides metribuzin, fenvalerate and aldicarb in 1989, and for metribuzin and phorate in 1990. Metribuzin concentrations up to 3.47 $ mu$g/l were detected in the tile drain water. Surface runoff samples had metribuzin concentrations up to 47.086 $ mu$g/l. Aldicarb was not detected in any of the water samples. Fenvalerate was detected in surface runoff at a level of 0.05 $ mu$g/l during the 1989 growing season. Phorate was not detected in subsurface drain water …  Lire la suite

This study analyzed the perceptions of 184 teachers in 38 member institutions of the Canadian Association of Independent Schools to determine the most important characteristics and indicators of school effectiveness. Review of the school effectiveness literature indicated eight characteristics of school effectiveness: leadership, expectations, mission, time on task, monitoring, basic skills, climate, and parent/community participation. In addition, research on school effectiveness has found certain procedures or activities that contribute to effective schooling, termed indicators for this study. Of the eight characteristics, creating a positive learning climate was ranked highest, as was the case in a recent study of private schools …  Lire la suite

Moral education in Japanese and Taiwanese primary schools is an important source of political socialization. An analysis of these two countries' moral education curricula reveals traditions which reinforce national solidarity and central governmental authority. Moreover, political ideology is merged with supporting academic, economic, and cultural values. This study examines the political ideology of the moral education curricula in Japanese and Taiwanese primary schools, the values and behavior promoted by these ideologies, as well as the similarities and differences between the Japanese and Taiwanese systems. It is shown that a distinctive feature of both systems is the emphasis placed on political …  Lire la suite

This thesis elaborates three aspects in the field of flow-induced vibrations associated with annular geometries. A method to find the unsteady fluid forces on a cylinder oscillating in annular turbulent flow is developed by considering the superposition of the turbulent fluctuating quantities on potential flow. The theory is compared with experiments. Then, the unsteady fluid forces acting on the vibrating cylinder walls of non-uniform annular configurations are computed by a method which performs the accurate time integration of the Navier-Stokes equations. It is the extension for unsteady flows of the method of artificial compressibility used for steady flows. A time-discretization …  Lire la suite

The merger provisions of the Competition Act proclaimed on June 19, 1986 are similar in with section 7 of the Clayton Act and the decisions of U.S. Courts in antitrust merger cases. In the U.S. and Canada a merger may be enjoined only if it is likely to lessen competition substantially. Subsection 92(2) and section 93 of the Competition Act supply a list of factors that may be used in the assessment of the probable impact on competition that a merger could have. The author discusses the meaning of subsection 92(2) of the Competition Act and the relevance of the …  Lire la suite

Closely linked to the notion of God, spirituality dominates throughout Gabrielle Roy's writings. The characters speculate about the meaning of life and death, about good and evil. Of all Roy's writings, it is undoubtedly in Alexandre Chenevert that these searching questions are most expressly depicted. In this thesis, we will study the manner in which the romantic background of Alexandre Chenevert reflects the religious experience of post-war French Canadians. Under the guise of distorted images, the novel does, in fact, hide an abundant network of themes referring to the religious context of the 1940's-1950's. This period was marked by challenging …  Lire la suite

A set ${ cal P} = P sb1,P sb2, ...,P sb{k}$ of polygons is called a k-cover of a simple polygon P if $P = cup sbsp{i=1}{k} P sb{i}$. It has been shown that finding k-covers of polygons by subpolygons of a given class is almost always NP-hard, whenever k is allowed to vary. Shermer (She91a) gave a linear time algorithm to determine if P has a two-cover by convex polygons, and to find one if it exists. A polygon P is star-shaped if it has a point which sees all the others, and $L sb{k}$-convex if every pair of …  Lire la suite

Le but de cette etude est de découvrir la perception que des professeures de français langue seconde ont de l'education interculturelle.  Lire la suite

This thesis studies the introduction of a priori structure into the design of learning systems based on artificial neural networks applied to sequence recognition, in particular to phoneme recognition in continuous speech. Because we are interested in sequence analysis, algorithms for training recurrent networks are studied and an original algorithm for constrained recurrent networks is proposed and test results are reported. We also discuss the integration of connectionist models with other analysis tools that have been shown to be useful for sequences, such as dynamic programming and hidden Markov models. We introduce an original algorithm to perform global optimization of …  Lire la suite

The aqueous behaviour of rhodium (III) (Rh) in chloride solutions was investigated with the objective of evaluating its response to solvent extraction with 8-hydroxyquinoline derivatives. A theoretical analysis of the abundance of the various chloro-complexes in solution revealed that monoaquo-pentachlororhodate and hexachlororhodate are the most common forms of Rh(III) in chloride solutions ($>$0.5M Cl$ sp{-}$) and that the relative abundance of hexachlororhodate may be lower than was previously reported. The extraction degree of Rh(III) with 8-hydroxyquinoline derivatives from solutions ranging in acidity from 0.7 to 8.0M and in chloride concentration from 0.7 to 4M was found to follow the calculated …  Lire la suite

To define the viral target sites of cellular permissive factors, simian virus 40-polyomavirus hybrid origins for DNA replication were formed by joining the auxiliary domain of one viral origin to the origin core of the other, and vice versa. The replicative capacity of these constructs were assessed in a number of mouse and monkey cell lines which express the large T antigen of polyomavirus or SV40. The results of this analysis showed that the auxiliary domains of the viral replication origins could substitute for one another in DNA replication, provided that the viral origin core and its cognate large T …  Lire la suite

"Les effets de plusieurs concentrations (0, 0.1, 1, 10 et 100 mg!L) de chlorure de tributylétain (TBT) sur les transformations de l'azote, contrôlées par les microorganismes du sédiment ont été étudiés. Les tests de réduction de l'acétylène et de l'inhibition par l'acétylène ont servi respectivement d'indicateurs pour la fiXation de l'azote et pour la denitrification. Un effet d'inhibition du produit toxique, relié à la dose, fut observé sur les cultures de surnageant du sédiment, ce dernier obtenu par centrifugation du sédiment. Cet effet n'a pas été observé sur les cultures de sédiment entier. Après huit jours d'incubation, les cultures de …  Lire la suite

This dissertation is a study of the first three plays that Jean-Jacques Rousseau wrote for the operatic stage: Iphis and La Decouverte du nouveau monde, both examples of the genre tragedie lyrique, and Les Muses galantes, an opera-ballet. Semiotic and poetic analyses bring to light striking resemblances between the dramatic situations depicted in the operas and the personal drama of the young Rousseau in love. As a whole, the operas reveal two distinct portraits of the self in love. The first, painted in colours of passion, reveals a self implicated in triangular relationships that are resolved through the abnegation of …  Lire la suite

By the methods of gel electrophoresis, protein blotting, and lectin staining, we compared the cell membrane glycoproteins of the human erythroleukemia cell line K562 with those of a NK-resistant subclone (Clone I), and a Con A-resistant subclone of Clone I called "Con A-R1". Although parental K562 and Clone I cells gave identical patterns, Con A-R1 contained two major populations of fucosylated proteins. Immunological analysis by flow cytometry and histochemical staining with lectins demonstrated that in Con A-R1 the H blood group epitope appeared concurrently with the disappearance of the $ alpha$1-3 fucosyllactosamine (Le$ sp{ rm X}$) epitope. Incubation of cells …  Lire la suite

Complementary analytical, numerical, and experimental investigations of fluid flow and heat transfer in closed-loop thermosyphons with vertical heated and cooled sections are presented in this thesis. A new model is proposed to couple the local results of numerical simulations performed in the heated and cooled section of a thermosyphon with a one-dimensional analytical model. The numerical simulations are based on a finite-volume numerical method which was formulated for the solution of laminar mixed-convection flows in vertical pipes with (or without) conjugate conduction in the pipe wall. Experimentally, a closed-loop thermosyphon was specially designed and constructed for this study. In the …  Lire la suite

The world faces an environmental crisis which can only be resolved through global co-operation and solidarity. Traditional international environmental law, based on the positivist notion of sovereignty, cannot offer adequate solutions. International environmental law must be based on a global approach founded on the notion of a common concern of humankind. This global approach has to provide a legal framework for the protection of the global environment. But it also must take into account the diverging needs and expectations of the different states. Furthermore, it must be realistic and cannot simply demand the replacement of sovereign states by a world …  Lire la suite

We consider various properties of the general three-way layout in experimental design, and begin with the information or C-matrices that play a key role, particularly with row-column and two-way elimination of heterogeneity designs. We introduce a new class of three-way layouts that satisfy a certain "generalized" decomposability property and obtain several new results for such layouts. Four different types of canonical correlations and associated canonical efficiency factors are considered and their connection with connectedness and orthogonality examined. We obtain a new inequality involving the average efficiency factors of a two-way elimination of heterogeneity design and of its two subdesigns. The …  Lire la suite

The metabolism of several anabolic 17$ alpha$-methyl steroids, namely formebolone, mestanolone, methandienone, methyltestosterone, oxandrolone, oxymetholone and stanozolol, were investigated. The identification of metabolites was based on GC/MS analysis of different derivatives, and chemical synthesis of corresponding reference steroids. Common metabolic reactions have been studied and structure-metabolism relationships were discussed. New biotransformation routes, such as oxidative pathways of 2-formyl and 2-hydroxymethylene steroids, have been unveiled. The mechanism of 17-epimerization of these 17$ beta$-hydroxy-17$ alpha$-methyl steroids in vivo has also been clarified. A simple and convenient method for the preparation of 17$ beta$-tertiary sulfate derivatives of these steroids has been developed. A …  Lire la suite

A new model is proposed for the calculation of relative depth doses for diagnostic radiology using a direct photon transport/ray tracing technique which incorporates both primary and first scatter dose. The x-ray spectra are generated from computer algorithms based on the Birch and Marshall semi-empirical model; the spectra are established by matching calculated and measured transmission data. The algorithms for the generation of x-ray spectra and for the calculation of depth doses are described. Relative depth doses are determined for a number of radiographic techniques. The calculations are compared with measured and published depth doses; the agreement is very good …  Lire la suite