Public and Private Preferences for Policies Related to Meat and Milk from Clones

Agricultural and Food Policy,

High-accuracy Geant4 simulation and semi-analytical modeling of nuclear resonance fluorescence

Nuclear resonance fluorescence (NRF) is a photonuclear interaction that enables highly isotope-specific measurements in both pure and applied physics scenarios. High-accuracy design and analysis of NRF measurements in complex geometries is aided by Monte Carlo simulations of photon physics and transport, motivating Jordan and Warren (2007) to develop the G4NRF codebase for NRF simulation in Geant4. In this work, we enhance the physics accuracy of the G4NRF code and perform improved benchmarking simulations. The NRF cross section calculation in G4NRF, previously a Gaussian approximation, has been replaced with a full numerical integration for improved accuracy in thick-target scenarios. A high-accuracy semi-analytical model of expected NRF count rates in a typical NRF measurement is then constructed and compared against G4NRF simulations for both simple homogeneous and more complex heterogeneous geometries. Agreement between rates predicted by the semi-analytical model and G4NRF simulation is found at a level of ${\sim}1\%$ in simple test cases and ${\sim}3\%$ in more realistic scenarios, improving upon the ${\sim}20\%$ level of the initial benchmarking study and establishing a highly-accurate NRF framework for Geant4.Comment: 16 pages, 6 figures, revised for peer revie

Experimental demonstration of an isotope-sensitive warhead verification technique using nuclear resonance fluorescence

Future nuclear arms reduction efforts will require technologies to verify that warheads slated for dismantlement are authentic without revealing any sensitive weapons design information to international inspectors. Despite several decades of research, no technology has met these requirements simultaneously. Recent work by Kemp et al. [Kemp RS, Danagoulian A, Macdonald RR, Vavrek JR (2016) Proc Natl Acad Sci USA 113:8618--8623] has produced a novel physical cryptographic verification protocol that approaches this treaty verification problem by exploiting the isotope-specific nature of nuclear resonance fluorescence (NRF) measurements to verify the authenticity of a warhead. To protect sensitive information, the NRF signal from the warhead is convolved with that of an encryption foil that contains key warhead isotopes in amounts unknown to the inspector. The convolved spectrum from a candidate warhead is statistically compared against that from an authenticated template warhead to determine whether the candidate itself is authentic. Here we report on recent proof-of-concept warhead verification experiments conducted at the Massachusetts Institute of Technology. Using high-purity germanium (HPGe) detectors, we measured NRF spectra from the interrogation of proxy 'genuine' and 'hoax' objects by a 2.52 MeV endpoint bremsstrahlung beam. The observed differences in NRF intensities near 2.2 MeV indicate that the physical cryptographic protocol can distinguish between proxy genuine and hoax objects with high confidence in realistic measurement times.Comment: 38 pages, 19 figures; revised for peer review and copy editing; addition to SI for realistic scenario projections; minor length reduction for journal requirement

Fluctuating shells under pressure

Thermal fluctuations strongly modify the large length-scale elastic behavior of crosslinked membranes, giving rise to scale-dependent elastic moduli. While thermal effects in flat membranes are well understood, many natural and artificial microstructures are modeled as thin elastic {\it shells}. Shells are distinguished from flat membranes by their nonzero curvature, which provides a size-dependent coupling between the in-plane stretching modes and the out-of-plane undulations. In addition, a shell can support a pressure difference between its interior and exterior. Little is known about the effect of thermal fluctuations on the elastic properties of shells. Here, we study the statistical mechanics of shape fluctuations in a pressurized spherical shell using perturbation theory and Monte Carlo computer simulations, explicitly including the effects of curvature and an inward pressure. We predict novel properties of fluctuating thin shells under point indentations and pressure-induced deformations. The contribution due to thermal fluctuations increases with increasing ratio of shell radius to thickness, and dominates the response when the product of this ratio and the thermal energy becomes large compared to the bending rigidity of the shell. Thermal effects are enhanced when a large uniform inward pressure acts on the shell, and diverge as this pressure approaches the classical buckling transition of the shell. Our results are relevant for the elasticity and osmotic collapse of microcapsules.Comment: To appear in PNAS; accepted version including Supplementary Informatio

An exploratory qualitative study of the relationship between an educational leader’s emotional intelligence and effective teams

Title from PDF of title page viewed on December 9, 2013Dissertation advisor:Jennifer FriendVitaIncludes bibliographical references (pages 148-159)Thesis (Ed.D.)--School of Education. University of Missouri--Kansas City, 2013Since the passage of the No Child Left Behind Act, the work of educators has become more demanding and complex. Not only is the work more difficult, the current era of accountability subjects teachers and educational leaders to more public scrutiny. This challenging work, coupled with increased accountability, is a formula for an intensely emotional environment. Leaders in education are charged with successfully managing this emotional environment. Because teams are such prevalent structures in organizations, emotional intelligence is often demonstrated through a leader’s work with teams he or she supervises. The purpose of this phenomenological case study was to explore the relationship between the emotional intelligence of educational leaders and the perceived effectiveness of teams they supervise. This qualitative research was conducted using the theoretical tradition of phenomenology. It was informed through heuristic research and narrative inquiry. The themes of the conceptual framework supporting this research are emotions, intelligence, leadership, and team effectiveness. Separately, there has been a substantial amount of research done on each of these themes. But there are fewer studies that analyze emotional intelligence in the context of leadership and team effectiveness. Adding to this body of knowledge can potentially help leaders use emotional intelligence and enable teams to be more effective.Introduction -- Review of Literature -- Methodology -- Results and discussion -- Recommendations -- Appendix A. Leader questionnaire -- Appendix B. Individual leader interview questions -- Appendix C. Focus group interview questions -- Appendix D. Leader writing prompt -- Appendix E. Focus group writing promp

ALTERNATIVE CALIBRATION AND AUCTION INSTITUTIONS FOR PREDICTING CONSUMER WILLINGNESS-TO-PAY FOR NON-GENETICALLY MODIFIED CORN CHIPS

This study explores two important issues in experimental economics: calibration and auction institution. Consumer willingness-to-pay bids for corn chips made with non-genetically modified ingredients are elicited from a 1st price and 2nd price auction. Results suggest that responses to scale differential questions, in a survey, accurately predict consumer willingness-to-pay bids. The 2 nd price auction induces a greater percentage of marginal bidders to offer a positive bid than a 1st price auction. However, average bid levels in the 1st and 2nd price auctions were not statistically different from one other. In a small and unrepresentative sample, 70 percent of student participants were unwilling to pay to exchange a bag of genetically modified corn chips for a bag of non-genetically modified corn chips. However, 20 percent of respondents were willing to pay at least $0.25/oz for the exchange.Consumer/Household Economics, Demand and Price Analysis,

Theory of Interacting Dislocations on Cylinders

We study the mechanics and statistical physics of dislocations interacting on cylinders, motivated by the elongation of rod-shaped bacterial cell walls and cylindrical assemblies of colloidal particles subject to external stresses. The interaction energy and forces between dislocations are solved analytically, and analyzed asymptotically. The results of continuum elastic theory agree well with numerical simulations on finite lattices even for relatively small systems. Isolated dislocations on a cylinder act like grain boundaries. With colloidal crystals in mind, we show that saddle points are created by a Peach-Koehler force on the dislocations in the circumferential direction, causing dislocation pairs to unbind. The thermal nucleation rate of dislocation unbinding is calculated, for an arbitrary mobility tensor and external stress, including the case of a twist-induced Peach-Koehler force along the cylinder axis. Surprisingly rich phenomena arise for dislocations on cylinders, despite their vanishing Gaussian curvature.Engineering and Applied SciencesMolecular and Cellular BiologyPhysic

Validation of Geant4's G4NRF module against nuclear resonance fluorescence data from 238^{238}U and 27^{27}Al

G4NRF is a simulation module for modeling nuclear resonance fluorescence (NRF) interactions in the Geant4 framework. In this work, we validate G4NRF against both absolute and relative measurements of three NRF interactions near 2.2 MeV in $^{238}$U and $^{27}$Al using the transmission NRF data from the experiments described in arXiv:1712.02904. Agreement between the absolute NRF count rates observed in the data and predicted by extensive Geant4+G4NRF modeling validate the combined Geant4+G4NRF to within $15$--$20\%$ in the $^{238}$U NRF transitions and $8\%$ in $^{27}$Al, for an average $13\%$ discrepancy across the entire study. The difference between simulation and experiment in relative NRF rates, as expressed as ratios of count rates in various NRF lines, is found at the level of ${\lesssim}4\%$, and is statistically identical to zero. Inverting the analysis, approximate values of the absolute level widths and branching ratios for $^{238}$U and $^{27}$Al are also obtained.Comment: 12 pages, 4 figures, 4 tables; revisions after peer review comments, chiefly making the paper more concise and the reporting of results more clea

Physical cryptographic verification of nuclear warheads

How does one prove a claim about a highly sensitive object such as a nuclear weapon without revealing information about the object? This paradox has challenged nuclear arms control for more than five decades. We present a mechanism in the form of an interactive proof system that can validate the structure and composition of an object, such as a nuclear warhead, to arbitrary precision without revealing either its structure or composition. We introduce a tomographic method that simultaneously resolves both the geometric and isotopic makeup of an object. We also introduce a method of protecting information using a provably secure cryptographic hash that does not rely on electronics or software. These techniques, when combined with a suitable protocol, constitute an interactive proof system that could reject hoax items and clear authentic warheads with excellent sensitivity in reasonably short measurement times. Keywords: isotopic tomography; nuclear weapons; disarmament; verificationUnited States. Department of Energy (Award DE-NA0002534