From the ground up : an agent-based model of regional structural change

The Saskatchewan farm sector is a dynamic system that is faced with the reality of farm consolidation and other structural adjustments. While structural adjustment may result in increased productivity at the farm-level, the declining farm population has a direct impact on rural regions. Given the economic difficulties now inherent in many rural regions, there has never been a more important time to improve our understanding of the structural dynamics of the farm sector. By utilizing agent-based methods, competition that exists between farm households in land markets is modelled in a dynamic framework. By modeling land markets in this manner, structural adjustments that occur due to the re-allocation of land among farm household becomes endogenous to the model. The farming simulation was validated by evaluating its ability to replicate actual structural shifts that occurred during the period of 1960-2000. The results obtained from the simulation were found to mirror historic shifts, which gives the author confidence that the parsimonious assumptions made are robust, yet still characteristic of farm level behaviour in the region. Other scenarios were simulated in order to estimate a counterfactual structural evolution of the modelled region, in the absence of government stabilization and support programs. Significant deviations are observed between the base and zero transfer scenarios with regards to the consolidation of farm assets among a declining number of farm households. Most significantly, the decline in farm numbers accelerated significantly in the late 1980’s in the zero transfer scenario compared to the base simulations. The application of an agent-based framework allowed for the study of regional structure with an emphasis on the behaviour and actions of the primary decisions makers within the system. While structural change is driven by a number of factors, the ability of a farm household to fully employ their labour resource was an important factor in the simulations. This contrasts with the finding that productive efficiency, and purchasing and market power at the farm level is not a necessary condition for the observed consolidation of farm assets

Analysis Of Pellet-Cladding Mechanical Interaction On U3Si2 Fuel With A Multi-Layer SiC Cladding Using Bison

U3Si2 is currently being considered as a possible replacement for the current light water reactor fuel, UO2. U3Si2’s high melting temperature, high uranium density, and high thermal conductivity are favorable in accident conditions, such as a loss of coolant accident. Improved accident performance is further expected when paired with a SiC/SiC cladding, since it provides relatively high strength and a high oxidation resistance. Modeling of U3Si2 and SiC/SiC in reactor is currently very important since much of their behavior is still unknown. By implementing models that describe the properties of U3Si2 and SiC/SiC into INL’s fuel performance code BISON, performance of this fuel/cladding combination can be compared to that of the standard UO2/Zircaloy. Included in these material models is a preliminary thermal creep model for U3Si2 based off of recent compressive creep data. In addition to the fuel performance analysis, due to the brittle nature of the monolithic SiC layer that surrounds the cladding, an in depth analysis on stresses in the cladding is done. Specifically performance during PCMI, when large interfacial pressures cause significant stresses in the cladding, and the effect of varying pelletcladding gap widths are analyzed

FIT-MART: Quantum Magnetism with a Gentle Learning Curve

We present a new open-source software package, FIT-MART, that allows non-experts to quickly get started simulating quantum magnetism. FIT-MART can be downloaded as a platform-idependent executable Java (JAR) file. It allows the user to define (Heisenberg) Hamiltonians by electronically drawing pictures that represent quantum spins and operators. Sliders are automatically generated to control the values of the parameters in the model, and when the values change, several plots are updated in real time to display both the resulting energy spectra and the equilibruim magnetic properties. Several experimental data sets for real magnetic molecules are included in FIT-MART to allow easy comparison between simulated and experimental data, and FIT-MART users can also import their own data for analysis and compare the goodness of fit for different models

Pulse Sequences for NMR Quantum Computers: How to Manipulate Nuclear Spins While Freezing the Motion of Coupled Neighbours

We show how to divide a coupled multi-spin system into a small subset of ``active'' spins that evolve under chemical shift or scalar coupling operators, and a larger subset of ``spectator'' spins which are returned to their initial states, as if their motion had been temporarily frozen. This allows us to implement basic one-qubit and two-qubit operations from which general operations on $N$-qubits can be constructed, suitable for quantum computation. The principles are illustrated by experiments on the three coupled protons of 2,3-dibromopropanoic acid, but the method is applicable to any spin-1/2 nuclei and to systems containing arbitrary numbers of coupled spins.Comment: 11 pages, 5 fig

NMR Quantum Logic Gates for Homonuclear Spin Systems

If NMR systems are to be used as practical quantum computers, the number of coupled spins will need to be so large that it is not feasible to rely on purely heteronuclear spin systems. The implementation of a quantum logic gate imposes certain constraints on the motion of those spins not directly involved in that gate, the so-called "spectator" spins; they must be returned to their initial states at the end of the sequence. As a result, a homonuclear spin system where there is appreciable coupling between every pair of spins would seem to require a refocusing scheme that doubles in complexity and duration for every additional spectator spin. Fortunately, for the more realistic practical case where long-range spin-spin couplings can be neglected, simpler refocusing schemes can be devised where the overall duration of the sequence remains constant and the number of soft pulses increases only linearly with the number of spectator spins. These ideas are tested experimentally on a six qubit system: the six coupled protons of inosine.Comment: 11 pages LaTeX plus 6 fig

Using Behavioral Realism to Estimate Presence: A Study of the Utility of Postural Responses to Motion Stimuli

We recently reported that direct subjective ratings of the sense of presence are potentially unstable and can be biased by previous judgments of the same stimuli (Freeman et al., 1999). Objective measures of the behavioral realism elicited by a display offer an alternative to subjective ratings. Behavioral measures and presence are linked by the premise that, when observers experience a mediated environment (VE or broadcast) that makes them feel present, they will respond to stimuli within the environment as they would to stimuli in the real world. The experiment presented here measured postural responses to a video sequence filmed from the hood of a car traversing a rally track, using stereoscopic and monoscopic presentation. Results demonstrated a positive effect of stereoscopic presentation on the magnitude of postural responses elicited. Posttest subjective ratings of presence, vection, and involvement were also higher for stereoscopically presented stimuli. The postural and subjective measures were not significantly correlated, indicating that nonproprioceptive postural responses are unlikely to provide accurate estimates of presence. Such postural responses may prove useful for the evaluation of displays for specific applications and in the corroboration of group subjective ratings of presence, but cannot be taken in place of subjective ratings

On the Convergence of the Electronic Structure Properties of the FCC Americium (001) Surface

Electronic and magnetic properties of the fcc Americium (001) surface have been investigated via full-potential all-electron density-functional electronic structure calculations at both scalar and fully relativistic levels. Effects of various theoretical approximations on the fcc Am (001) surface properties have been thoroughly examined. The ground state of fcc Am (001) surface is found to be anti-ferromagnetic with spin-orbit coupling included (AFM-SO). At the ground state, the magnetic moment of fcc Am (001) surface is predicted to be zero. Our current study predicts the semi-infinite surface energy and the work function for fcc Am (001) surface at the ground state to be approximately 0.82 J/m2 and 2.93 eV respectively. In addition, the quantum size effects of surface energy and work function on the fcc Am (001) surface have been examined up to 7 layers at various theoretical levels. Results indicate that a three layer film surface model may be sufficient for future atomic and molecular adsorption studies on the fcc Am (001) surface, if the primary quantity of interest is the chemisorption energy.Comment: 34 pages, 9 figure

Bostonia: The Boston University Alumni Magazine. Volume 20

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Stakeholder Approach to Better Understand Psychological Health Services in the Military

Ensuring the psychological well-being of service members and their families has emerged as one of the principal challenges of today‟s armed services. Given that the system of care of psychological health services in the United States Military cannot be divorced from the large healthcare delivery system, an enterprise perspective is needed to truly understand the dynamics of the system of care. This paper makes two key contributions: it identifies the key stakeholders of the military health enterprise with respect to psychological health, and analyzes the espoused senior leadership values over the last decade as seen in the stakeholder reports. This stakeholder analysis highlights the challenges faced in melding the constituent organizations into an enterprise, especially in the face of leadership turnover. The thematic analysis of senior leadership values shows an evolution of focus from managing execution of care to a more holistic emphasis on healthy lifestyles and psychological health

Type IIP Supernova SN 2004et: A Multi-Wavelength Study in X-Ray, Optical and Radio

We present X-ray, broad band optical and low frequency radio observations of the bright type IIP supernova SN 2004et. The \cxo observed the supernova at three epochs, and the optical coverage spans a period of $\sim$ 470 days since explosion. The X-ray emission softens with time, and we characterise the X-ray luminosity evolution as \Lx \propto t^{-0.4}. We use the observed X-ray luminosity to estimate a mass-loss rate for the progenitor star of \sim \ee{2}{-6} M_\odot \mathrm{yr}^{-1}. The optical light curve shows a pronounced plateau lasting for about 110 days. Temporal evolution of photospheric radius and color temperature during the plateau phase is determined by making black body fits. We estimate the ejected mass of $^{56}$Ni to be 0.06 $\pm$ 0.03 M$_\odot$. Using the expressions of Litvinova & Nad\"{e}zhin (1985) we estimate an explosion energy of (0.98 $\pm$ 0.25) $\times 10^{51}$ erg. We also present a single epoch radio observation of SN 2004et. We compare this with the predictions of the model proposed by Chevalier et al. (2006). These multi-wavelength studies suggest a main sequence progenitor mass of $\sim$ 20 M$_\odot$ for SN 2004et.Comment: 13 Figures, Accepted for Publication in MNRA