1,740 research outputs found
(Never) Mind your p's and q's: Von Neumann versus Jordan on the Foundations of Quantum Theory
No full textIn early 1927, Pascual Jordan (1927b) published his version of what came to be known as the Dirac-Jordan statistical transformation theory. Later that year and partly in response to Jordan, John von Neumann (1927a) published the modern Hilbert space formalism of quantum mechanics. Central to both formalisms are expressions for conditional probabilities of finding some value for one quantity given the value of another. Beyond that Jordan and von Neumann had very different views about the appropriate formulation of problems in the new theory. For Jordan, unable to let go of the analogy to classical mechanics, the solution of such problems required the identification of sets of canonically conjugate variables, i.e., p’s and q’s. Jordan (1927e) ran into serious difficulties when he tried to extend his approach from quantities with fully continuous spectra to those with wholly or partly discrete spectra. For von Neumann, not constrained by the analogy to classical physics and aware of the daunting mathematical difficulties facing the approach of Jordan (and, for that matter, Dirac (1927)), the solution of a problem in the new quantum mechanics required only the identification of a maximal set of commuting operators with simultaneous eigenstates. He had no need for p’s and q’s. Related to their disagreement about the appropriate general formalism for the new theory, Jordan and von Neumann stated the characteristic new rules for probabilities in quantum mechanics somewhat differently. Jordan (1927b) was the first to state those rules in full generality, von Neumann (1927a) rephrased them and then sought to derive them from more basic considerations (von Neumann, 1927b). In this paper we reconstruct the central arguments of these 1927 papers by Jordan and von Neumann and of a paper on Jordan’s approach by Hilbert, von Neumann, and Nordheim (1928). We highlight those elements in these papers that bring out the gradual loosening of the ties between the new quantum formalism and classical mechanics
Family, followers and friends : the socio-political dynamics of the Anglo-Norman aristocracy, 1100-1204
No full textThree groups are examined: the family, followers and friends. The structure,functions and tensions of these groups are described and their dynamics analysed in the fields of decision making and conflict resolution.
The approach offers a dialectic between Latin and French sources, historical and literary, and social science theories. This opens up new avenues for analysis and allows a holistic description of medieval politics and society.
The family comprised parents and their children. Within this small unit affection was very strong; outside, it quickly declined. Although uncles and nephews had political links there was considerably less emotional attachment between them than between parent-child and sibling relationships.
Three types of follower are examined: household retainers, enfeoffed tenants and 'neighbours'. Household knights had the strongest emotional bonds to their lord and were
seen as the most loyal. Tenants who performed homage were called `men'; 'vassal' is shown to mean 'good follower'. An aristocrat exercised considerable control within his lands and beyond them he maintained some power. In these areas people may have obeyed his will without having any direct link with him. Such people were often called 'neighbours'.
Informal influences such as love and fear are shown to have more force than the formal bonds created through homage and oaths. Concepts of 'treason' and 'defiance' are also examined.
Five types of friendship are identified: friendship as courtesy, formal friendship, emotional friendship, company and companionship. Calling someone 'friend' was a sign of
politeness. Political agreements, often termed covenants, created formal bonds of friendship. A new methodology for investigating emotional friendship is proposed. Groups with a strong identity were called companies. Companionship was a close bond, usually between two men, that combined elements of formal and emotional friendship.
This description of the socio-political dynamics of the aristocracy offers an alternative to earlier models and greatly enhances our understanding of Anglo-Norman politics and society
Molecular characterization of Giardia spp. and Cryptosporidium spp. from dogs and coyotes in an urban landscape suggests infrequent occurrence of zoonotic genotypes
No full textGiardia spp. and Cryptosporidium spp. are common gastrointestinal parasites with the potential for zoonotic transmission. This study aimed to (1) determine the genotypes occurring in dogs and coyotes occupying a similar urban area; (2) determine if these hosts were infected with potentially zoonotic genotypes; (3) provide baseline molecular data. In August and September 2012, 860 dog owners living in neighborhoods bordering six urban parks in Calgary, Alberta, Canada, provided faecal samples from their dogs. From March 2012 through July 2013, 193 coyote faeces were also collected from five of six of the same parks. Direct immunofluorescence microscopy (DFA) indicated that Giardia spp. and Cryptosporidium spp. infected a total of 64 (7.4%) and 21 (2.4%) dogs, as well as 15 (7.8%) and three (1.6%) coyotes, respectively. Semi-nested, polymerase chain reactions targeting the 16S small-subunit ribosomal ribonucleic acid (SSU rRNA) and 18S SSU rRNA genes of Giardia spp. and Cryptosporidium spp., respectively, were conducted on samples that screened positive by DFA, and products were sequenced and genotyped. Dogs were infected with Giardia intestinalis canid-associated assemblages C (n=14), D (n=13), and Cryptosporidium canis (n=3). Similarly, G. intestinalis assemblages C (n=1), D (n=1) and C. canis (n=1), were detected in coyotes, as well as G. intestinalis assemblage A (n=1) and Cryptosporidium spp. vole genotype (n=1). Dogs and coyotes were predominantly infected with host-specific genotypes and few potentially zoonotic genotypes, suggesting that they may not represent a significant risk for zoonotic transmission of these parasites in urban areas where these hosts are sympatric
Plan for the improvement of the Gowanus Canal, Brooklyn, New York
No full textThesis (B.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1906 (first author), and Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Civil and Sanitary Engineering, 1906 (second author).by Norman P. Gerhard and Charles F. Breitzke.B.S
Escherichia coli contamination of rural well water in Alberta, Canada is associated with soil properties, density of livestock and precipitation
No full textWaterborne outbreaks of infectious disease continue to be a public health risk, particularly those in areas where testing of private and public small system groundwater systems is left to the owners/overseers of these wells who may not recognize the importance of testing and treatment. Recognizing factors associated with contamination of wells is important for public safety and can encourage well owners/overseers to test regularly and properly maintain drinking water supplies. Tests results for presence/absence of total coliforms and Escherichia coli for private and public untreated well water for the years 2010-2012 (n=56,609) were provided by the Alberta Provincial Laboratory for Public Health. Tests were geolocated with the Alberta Township Survey System and aggregated to the quarter section. Agricultural independent variables were provided by the Canadian Agricultural Census and monthly cumulative precipitation was calculated using Alberta Agriculture and Forestry’s website of weather station data. Overall frequency of E. coli-positive wells in the study was 1.4%. A marginal multivariable logistic regression model was fit using generalized estimating equations to account for repeat testing of some quarter sections. Three significant factors associated with increased E. coli-positive untreated drinking water wells were identified: soil properties (KSat and sand content), animal density and monthly cumulative precipitation
Hydrographic data from Oregon coastal waters: June 1960 through May 1961
No full textby Bruce Wyatt and Norman F. Kujala ; edited by Elizabeth Strong.This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Includes bibliographical references (page 3).Office of Naval Research Nonr 1286(10) NR 083-102.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
Perceptions of power in the contemporary american novel
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Florianópolis, 1996.Este estudo tenta delinear como o poder - tanto institutional quanto representacional - é percebido na ficção norte-americana do período pós-guerra até o presente. O trabalho examina romancistas representativos e analisa uma série de trabalhos individuais dentro de seu conteúdo histórico. Na primeira parte, teorias sócio-políticas sobre o poder fornecem o suporte teórico para detectar como o poder é visto nos romances. A segunda parte discute o romance político pós-guerra, Gore Vidal e Norman Mailer, entre outros. Constata-se que uma percepção de poder Weberiana (adversarial) de poder por parte dos romancistas da segunda parte é substuída por uma visão Foucaltiana (poder insidiosamente filtrado) por parte dos romancistas da terceira parte, o que corresponde a transformação da sociedade contemporânea, sua política e cultura no capitalismo multinacional, durante e depois dos anos 60
Christian F. Feest, ed. Studies in American Indian Art: A Memorial Tribute to Norman Feder
No full textLike few of his contemporaries, Norman Feder helped shape the study of American Indian art. In a career spanning four decades as hobbyist craftsman, author, curator, and editor, Feder contributed to the theoretical and methodological foundation of a discipline about to emerge from the narrow interests of museum anthropologists and devoted amateurs into public prominence and widespread appreciation
Evaluating the reliability of NAND multiplexing with PRISM
No full textProbabilistic-model checking is a formal verification technique for analyzing the reliability and performance of systems exhibiting stochastic behavior. In this paper, we demonstrate the applicability of this approach and, in particular, the probabilistic-model-checking tool PRISM to the evaluation of reliability and redundancy of defect-tolerant systems in the field of computer-aided design. We illustrate the technique with an example due to von Neumann, namely NAND multiplexing. We show how, having constructed a model of a defect-tolerant system incorporating probabilistic assumptions about its defects, it is straightforward to compute a range of reliability measures and investigate how they are affected by slight variations in the behavior of the system. This allows a designer to evaluate, for example, the tradeoff between redundancy and reliability in the design. We also highlight errors in analytically computed reliability bounds, recently published for the same case study
A Polyphasic Perspective on Escherichia coli Niche-Specificity: The Characterization of Naturalized, Wastewater-Specific E. coli and the Emergence of Wastewater Treatment Resistance in the Microbial World
No full textAlthough typically considered to be capable of colonizing and transiting between several different niches, evidence suggests that the Escherichia coli species exhibits a significant degree of host- and niche-specificity. This has led to the hypothesis that E. coli taxonomy may be more appropriately described using a ‘species-complex’ model, consisting of several distinct niche-specific groups known as ‘ecotypes’. While various microbial taxonomic schemes have been developed to date, current conventional microbial diagnostic and classification methods appear to be unsuitable for reliably identifying and differentiating between microbial ecotypic groups.
Herein, we describe the application of a logic regression-based workflow for the discovery of putative E. coli ecotypes, and the subsequent polyphasic characterization of the specific genotypic, phenotypic, and ecotypic adaptations underlying their niche-specificity. Building on previous studies in our laboratory, logic regression was used to analyse the sequence variation contained within intergenic regions (ITGRs) across the E. coli genome. Reinforcing previous findings, logic regression modelling was found to generate highly niche-specific single nucleotide polymorphism (SNP) biomarkers across a wide range of host and environmental niches that not only appeared to demarcate putative E. coli ecotypes, but also could be used for the source (i.e., ecotype) attribution of unknown environmental strains. Interestingly, in addition to being effective for differentiating between host-associated E. coli ecotypes, logic regression also consistently distinguished wastewater-derived strains from their host-associated counterparts, suggesting they may represent a unique E. coli ecotype adapted to engineered environments as primary niches.
Through a polyphasic approach, various characteristics underlying this ‘naturalized-engineered’ ecotype were identified. Wastewater- and meat plant-derived strains were found to group into naturalized-engineered-associated sequence types (ST635 and ST399) and several serotypes, representing distinct lineages that may have independently emerged across food- and water-associated engineered environments. Strains belonging to these naturalized-engineered ecotypic groups were characterized by unique genetic traits, as they were enriched in genes and genetic markers associated with biofilm formation, microbial defense, and stress resistance (i.e., against DNA-damaging stimuli, oxidizing agents, heat, heavy metals), but lacked host-adaptive genes related to colonization and virulence. Recapitulating these genotypic findings, wastewater-specific (WWS) E. coli strains were also characterized by various phenotypic adaptations that could promote their survival across the wastewater treatment train, including enhanced resistance to heat, slower growth kinetics, and enhanced biofilm formation under nutrient-limiting and low temperature conditions.
As such, with the WWS strains as a model system, we were able to demonstrate the utility of our logic regression-based, polyphasic workflow for the exploration of putative ecotypes within the E. coli species. While these findings have important conceptual implications for prokaryotic taxonomy, especially in how bacterial species may be defined, the characterization of a wastewater treatment resistant ecotype implies that other E. coli populations could also be evolving resistance to wastewater disinfection. Reflecting this, comprehensive comparative genomic approaches revealed that other, non-naturalized wastewater-derived E. coli strains surviving wastewater treatment were virtually identical to clinically relevant extraintestinal pathogenic E. coli (ExPEC) strains. Our findings, therefore, also point to a concerning public health prospect – that pathogenic microbes could similarly be evolving resistance to wastewater treatment and disinfection
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