602 research outputs found
James Bond: international man of gastronomy
No full textThis article is concerned with the representation of food and drink in Ian Fleming’s James Bond novels. In particular, it examines how the author uses Bond’s culinary knowledge and habits of consumption as an important constituent of his hero’s character. Similarly, the food choices of other characters, notably villains, are shown to be linked, by Fleming, to core aspects of their identity − principally their ethnicity. Bond’s impulse to observe and classify, very much in evidence in the novels’ food sequences, is examined in terms of the texts’ construction of Bond as a skilled identifier of signs
Solving eigenvalue response matrix equations with nonlinear techniques
No full textThis paper presents new algorithms for use in the eigenvalue response matrix method (ERMM) for reactor eigenvalue problems. ERMM spatially decomposes a domain into independent nodes linked via boundary conditions approximated as truncated orthogonal expansions, the coefficients of which are response functions. In its simplest form, ERMM consists of a two-level eigenproblem: an outer Picard iteration updates the k-eigenvalue via balance, while the inner λ -eigenproblem imposes neutron balance between nodes. Efficient methods are developed for solving the inner λ-eigenvalue problem within the outer Picard iteration. Based on results from several diffusion and transport benchmark models, it was found that the Krylov-Schur method applied to the λ -eigenvalue problem reduces Picard solver times (excluding response generation) by a factor of 2–5. Furthermore, alternative methods, including Picard acceleration schemes, Steffensen’s method, and Newton’s method, are developed in this paper. These approaches often yield faster k-convergence and a need for fewer k-dependent response function evaluations, which is important because response generation is often the primary cost for problems using responses computed online (i.e., not from a precomputed database). Accelerated Picard iteration was found to reduce total computational times by 2–3 compared to the unaccelerated case for problems dominated by response generation. In addition, Newton’s method was found to provide nearly the same performance with improved robustness
Feast or flee: government payments and labor migration from agriculture in the United States
No full textGovernment payments have been a part of agriculture since 1933 and at no time has the government stated a policy objective of decreasing the agricultural labor force. The reality of the matter may be considerably different. Using time series data and new econometric techniques, this study finds agricultural policy may have an unintended impact on labor migration. Specifically, we find that government payments increased labor migration from the farm. From 1939 to 2007, increased direct government payments resulted in greater migration of labor from agriculture. Government policy appears to have shown limited success at sustaining the agricultural labor force
Selective anticancer activity of a hexapeptide with sequence homology to a non-kinase domain of Cyclin Dependent Kinase 4
No full textBackground: cyclin-dependent kinases 2, 4 and 6 (Cdk2, Cdk4, Cdk6) are closely structurally homologous proteins which are classically understood to control the transition from the G1 to the S-phases of the cell cycle by combining with their appropriate cyclin D or cyclin E partners to form kinase-active holoenzymes. Deregulation of Cdk4 is widespread in human cancer, CDK4 gene knockout is highly protective against chemical and oncogene-mediated epithelial carcinogenesis, despite the continued presence of CDK2 and CDK6; and overexpresssion of Cdk4 promotes skin carcinogenesis. Surprisingly, however, Cdk4 kinase inhibitors have not yet fulfilled their expectation as 'blockbuster' anticancer agents. Resistance to inhibition of Cdk4 kinase in some cases could potentially be due to a non-kinase activity, as recently reported with epidermal growth factor receptor. Results: a search for a potential functional site of non-kinase activity present in Cdk4 but not Cdk2 or Cdk6 revealed a previously-unidentified loop on the outside of the C'-terminal non-kinase domain of Cdk4, containing a central amino-acid sequence, Pro-Arg-Gly-Pro-Arg-Pro (PRGPRP). An isolated hexapeptide with this sequence and its cyclic amphiphilic congeners are selectively lethal at high doses to a wide range of human cancer cell lines whilst sparing normal diploid keratinocytes and fibroblasts. Treated cancer cells do not exhibit the wide variability of dose response typically seen with other anticancer agents. Cancer cell killing by PRGPRP, in a cyclic amphiphilic cassette, requires cells to be in cycle but does not perturb cell cycle distribution and is accompanied by altered relative Cdk4/Cdk1 expression and selective decrease in ATP levels. Morphological features of apoptosis are absent and cancer cell death does not appear to involve autophagy. Conclusion: these findings suggest a potential new paradigm for the development of broad-spectrum cancer specific therapeutics with a companion diagnostic biomarker and a putative functional site for kinase-unrelated activities of Cdk4
Diversity oriented, computer guided catalyst design: Application of chemoinformatics to catalysis
No full textThe first half of this thesis (Chapter 2 and 3) focus on the development and application of a diversity oriented, computer guided catalyst optimization chemoinformatic workflow. This process seeks to combine the power of chemoinformatic diversity analysis and QSAR modeling with diversity and discovery oriented synthesis to rapidly and efficiently design active and selective catalysts for unsolved problems and novel transformations in synthetic organic chemistry. Chapter 2 focuses on the iterations of development that have resulted in the current chemoinformatic workflow, and Chapter 3 focuses on applications of the chemoinformatic methods developed for the workflow towards problems in enantioselective catalysis.
The second half of this thesis (Chapter 4) focuses on the use of chemoinformatics to develop design criteria for active phase-transfer catalysts. The most common parameter used to predict PTC rates, the ammonium ion accessibility, q, is defined in such a way that limits its use to straight-chain tetraalkylammonium catalysts. To find a general descriptor of rate, eight linear, symmetrical tetraalkylammonium cations were examined to determine if a model containing broadly applicable descriptors could be found. The catalytic activity of these salts was determined under PTC conditions (operating under an interfacial, transport-rate limiting mechanism) and was compared with these molecular descriptors. Models could be generated from the ammonium ion accessibility parameter q and the amphiphilic cross-sectional area descriptor (XSA), and each gave a correlative model predicting the rate of alkylation. However, a similar model cannot be generated from a descriptor that is a direct measure of ammonium ion accessibility, the solvent accessible ammonium surface area (NC4_SA). These models lead to the conclusion that q must approximate catalyst properties other than ammonium ion accessibility. Additionally, the relationship between XSA and rate demonstrates that XSA approximates the complex behavior of ammonium ions at the interfacial region of a biphasic system, allowing for its use as a general descriptor for transport-limiting PTC rate approximationsSubmission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2020-05-01The student, Jeremy Henle, accepted the attached license on 2018-01-18 at 15:25.The student, Jeremy Henle, submitted this Dissertation for approval on 2018-01-18 at 15:34.This Dissertation was approved for publication on 2018-01-19 at 14:24.DSpace SAF Submission Ingestion Package generated from Vireo submission #12014 on 2018-08-31 at 17:24:31Made available in DSpace on 2018-09-04T20:46:44Z (GMT). No. of bitstreams: 3
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Revealing hidden dynamics via single nanoparticle studies
No full textSubmission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-08-01Nanomaterials constitute the frontier in materials science. Materials with such length scales are typically the minimum units which contain sufficient atoms to display the collective properties which we typically think of a discerning solid-state materials from individual atoms. Characterization techniques, predominantly electron microscopy and tip based methods, have rapidly advance in recent years and now provide routine methods for structural characterization on such length scales. However these methods are fundamentally incompatible with typical environments in which such materials find applications, i.e. in solution under reactive conditions. Herein I seek to develop methodologies based on simple optical microscopy to study individual nano-sized pieces of materials undergoing dynamical restructuring and surface binding events, both to demonstrate the feasibility of the methodology, as well as probe some of the fundamental statistical behavior of such materials under these conditions.
Specifically, I focus two predominant systems. The first is a well-studied model system in surface science, that of alkanethiol binding to the surface of individual Ag nanoparticles. This work demonstrates that (surface) structural heterogeneity can influence rates of binding, particularly varying degrees of negative feedback on subsequent binding events depending on the nanoparticle. Secondly, I study galvanic exchange reactions, also on individual Ag nanoparticles. By tuning reactivity of the ionic metal complex inducing replacement, I demonstrate a transition between surface reaction limited and critically driven reaction dynamics. Critical dynamics manifest as distinct temporal offsets between individual nanoparticles in an ensemble undergoing this transition. Such dynamics as demonstrably not the result of structural (or surface structural) heterogeneities, but rather arise due to the stochastic nature of the initial of the critical event at near equilibrium reaction conditions. It is demonstrated that the surface structure does scale the relative concentration at the surface however, which in turn affects the overall ensemble rate, but not the reaction mechanism. Such insight is important from a nanomaterials synthesis prospective, for a detailed understanding of nanoscale corrosion and for accurately model the behavior of nanomaterials transformations.The student, Jeremy Smith, accepted the attached license on 2016-06-10 at 13:55.The student, Jeremy Smith, submitted this Dissertation for approval on 2016-06-10 at 14:04.This Dissertation was approved for publication on 2016-06-10 at 15:52.DSpace SAF Submission Ingestion Package generated from Vireo submission #9655 on 2016-11-10 at 12:19:20Made available in DSpace on 2016-11-10T18:27:28Z (GMT). No. of bitstreams: 5
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Multigroup diffusion preconditioners for multiplying fixed-source transport problems
No full textSeveral preconditioners based on multigroup di usion are developed for application to multiplying fi xed-source transport problems using the discrete ordinates method. By starting from standard, one-group, diff usion synthetic acceleration (DSA), a multigroup diff usion preconditioner is constructed that shares the same fi ne mesh as the transport problem. As a cheaper but effective alternative, a two-grid, coarse-mesh, multigroup diff usion preconditioner is examined, for which a variety of homogenization schemes are studied to generate the coarse mesh operator. Finally, a transport-corrected diff usion preconditioner based on application of the Newton-Shulz algorithm is developed. The results of several numerical studies indicate the coarse-mesh, diff usion preconditioners work very well. In particular, a coarse-mesh, transport-corrected, diff usion preconditioner reduced the computational time of multigroup GMRES by up to a factor of 17 and outperformed best-case Gauss-Seidel results by over an order of magnitude for all problems studied
Open Access: Faculty and graduate student panel discussion
No full textThe Open Access Week panel discussion includes Virginia Tech graduate students, faculty, and alumni who have been involved in open access publishing from the author and editor perspectives. Each will relate their experience with open access, followed by a discussion, including questions from the audience. Light refreshments will be served. Panelists include:
- Carola Haas (faculty, Fish and Wildlife Conservation)
- Scott King (faculty, Geophysics)
- Alison Burke (PhD candidate, Biomedical Sciences)
- Sascha Engel (PhD candidate, ASPECT)
- Titilola Obilade (former adjunct faculty, School of Education)
- Jeremy Ernst (faculty, Integrative STEM Education)Virginia Tech. University LibrariesThis panel discussion was held in the Multipurpose Room of Virginia Tech's Newman Library on October 19, 2015 at 5:30pm EST
A High-Order, Time-Dependent, Response Matrix Method for Reactor Kinetics
No full textA high-order, transient transport method based on the response matrix formalism is developed for application to reactor kinetics problems. The method combines recent advances in both static and transient response matrix methods with an explicit response-based treatment of delayed neutron precursors first proposed in the 1970s. In addition, an orthogonal basis for the time variable based on point kinetics is proposed as an alternative to a strictly polynomial basis. The method is demonstrated on infinite medium problems, the results of which show that the method can be successfully applied to reactor kinetics problems with and without precursors
The theory of eucharistic presence in the early Caroline divines, examined in its European theological setting
No full textThe question of Christ's presence in the eucharist was an issue
which caused great controversy in the Reformation period, and which
continued to evoke dispute during the seventeenth century. Various
interpretations of the Caroline divines' teaching on the eucharistic
presence have been offered, but often they seem either to indicate the
theological position of the writer rather than that of the theologians
considered, or to ignore the broader context of eucharistic doctrine.
The purpose of this study, therefore, was 1. to investigate the
theology of eucharistic presence in the thinking of several seventeenth-century
Anglican divines, and 2. to examine their teaching in relation
to the sixteenth-century Anglican heritage and the various continental
sacramental doctrines, Reformed, Lutheran, Roman Catholic and Eastern
Orthodox.
To accomplish this goal, eight theologians were chosen for examination:
Adrianus Saravia, Lancelot Andrewes, John Cosin, Richard
Montague, William Forbes, William Laud, Jeremy Taylor and Herbert
Thorndike. When available, nineteenth-century editions of their works
were used; otherwise, seventeenth-century texts were employed.
Similarly, modern editions of Roman, Orthodox, Lutheran and Reformed
writings were utilized when possible. Thy examination of eucharistic
teaching included seven major points: 1. the sacrament as mystery,
2. eucharistic change, 3. the relationship between Christ's body and
the bread, 4. eucharistic communion, 5. the nature of Christ's body in
the sacrament, 6. consecration, and 7. adoration in the eucharist.
This study has shown that there was great diversity in the
thinking of the Caroline divines (although they did not treat the
subject of eucharistic presence with equal detail or depth); no
unified understanding of sacramental presence was expressed. Reformed
ideas inherited from the previous century remained strong, but new
tendencies toward other understandings of the eucharist can be
discerned. The period, therefore, can be seen to represent a new
stage in the history of Anglican eucharistic doctrine
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