Alien Registration- Barnaby, Murray D. (Bucksport, Hancock County)

https://digitalmaine.com/alien_docs/19267/thumbnail.jp

Reheating the Universe After Multi-Field Inflation

We study in detail (p)reheating after multi-field inflation models with a particular focus on N-flation. We consider a variety of different couplings between the inflatons and the matter sector, including both quartic and trilinear interactions with a light scalar field. We show that the presence of multiple oscillating inflatons makes parametric resonance inefficient in the case of the quartic interactions. Moreover, perturbative processes do not permit a complete decay of the inflaton for this coupling. In order to recover the hot big bang, we must instead consider trilinear couplings. In this case we show that strong nonperturbative preheating is possible via multi-field tachyonic resonance. In addition, late-time perturbative effects do permit a complete decay of the condensate. We also study the production of gauge fields for several prototype couplings, finding similar results to the trilinear scalar coupling. During the course of our analysis we develop the mathematical theory of the quasi-periodic Mathieu equation, the multi-field generalization of the Floquet theory familiar from preheating after single field inflation. We also elaborate on the theory of perturbative decays of a classical inflaton condensate, which is applicable in single-field models also.Comment: 46+1 pages, 19 figure

Monitoring the performance of residents during training in off-pump coronary surgery.

OBJECTIVE: Control charts (eg, cumulative sum charts) plot changes in performance with time and can alert a surgeon to suboptimal performance. They were used to compare performance of off-pump coronary artery bypass surgery between a consultant and four resident surgeons and to compare performance of off-pump coronary artery bypass surgery and conventional coronary artery bypass grafting within surgeons. METHODS: Data were analyzed for consecutive patients undergoing coronary artery bypass grafting who were operated on by one consultant or one of four residents. Conversions were analyzed by intention to treat. Perioperative death or one or more of 10 adverse events constituted failure. Predicted risks of failure for individual patients were derived from the study population. Variable life-adjusted displays and risk-adjusted sequential probability ratio test charts were plotted. RESULTS: Data for 1372 patients were analyzed; 769 of the procedures were off-pump coronary artery bypass operations (56.0%). The consultant operated on 382 patients (293 off-pump, 76.7%), and the residents operated on 990 (474 off-pump, 47.9%). Patients operated on by residents tended to be older, more obese, more likely to require an urgent operation, and more likely to need a circumflex artery graft but less likely to have triple-vessel disease. There were 7 conversions (consultant 5, residents 2). The overall failure rate was 8.5% (9.2% for consultant's operations and 8.2% for residents' operations), including 10 deaths (0.7%). Predicted and observed risks of failure were similar for all five surgeons. After 100 off-pump coronary artery bypass operations, performance was the same or better for the residents as for the consultant. For all surgeons, performance was the same or better for off-pump as for conventional coronary artery bypass grafting. CONCLUSIONS: Off-pump coronary artery bypass surgery can be safely taught to cardiothoracic residents. Implementation of continuous performance monitoring for residents is practicable

Using simulation to develop business strategy skills of entrepreneurs - Some reflections on a pilot

It is recognized that the value of entrepreneurship education and the recruitment of practising entrepreneurs for such learning programmes can be problematic. This raises an important and challenging issue for universities when they are increasingly being asked to develop the leadership and management capabilities of entrepreneurs. In this account of practice, the authors explore the role for business simulation in the development of existing entrepreneurs’ and small business leaders’ strategic decision-making skills. The article describes and reflects on a pilot business simulation course, considering the challenges in the planning, the engagement of entrepreneurs and the delivery of the programme. It provides insights into the value of introducing this form of learning experience and exposes the significant challenges associated with engaging small business leaders

Phenomenology of a Pseudo-Scalar Inflaton: Naturally Large Nongaussianity

Many controlled realizations of chaotic inflation employ pseudo-scalar axions. Pseudo-scalars \phi are naturally coupled to gauge fields through c \phi F \tilde{F}. In the presence of this coupling, gauge field quanta are copiously produced by the rolling inflaton. The produced gauge quanta, in turn, source inflaton fluctuations via inverse decay. These new cosmological perturbations add incoherently with the "vacuum" perturbations, and are highly nongaussian. This provides a natural mechanism to generate large nongaussianity in single or multi field slow-roll inflation. The resulting phenomenological signatures are highly distinctive: large nongaussianity of (nearly) equilateral shape, in addition to detectably large values of both the scalar spectral tilt and tensor-to-scalar ratio (both being typical of large field inflation). The WMAP bound on nongaussianity implies that the coupling, c, of the pseudo-scalar inflaton to any gauge field must be smaller than about 10^{2} M_p^{-1}.Comment: 45 pages, 7 figure

Inhomogeneous tachyon condensation

We investigate the spacetime-dependent condensation of the tachyon in effective field theories. Previous work identified singularities in the field which appear in finite time: infinite gradients at the kinks, and (in the eikonal approximation) caustics near local minima. By performing a perturbation analysis, and with numerical simulations, we demonstrate and explain key features of the condensation process: perturbations generically freeze, and minima develop singular second derivatives in finite time (caustics). This last has previously been understood in terms of the eikonal approximation to the dynamics. We show explicitly from the field equations how this approximation emerges, and how the caustics develop, both in the DBI and BSFT effective actions. We also investigate the equation of state parameter of tachyon matter showing that it is small, but generically non-zero. The energy density tends to infinity near field minima with a charateristic profile. A proposal to regulate infinities by modifying the effective action is also studied. We find that although the infinities at the kinks are successfully regularised in the time-dependent case, caustics still present.Comment: 4 figures,19p

On Tunnelling In Two-Throat Warped Reheating

We revisit the energy transfer necessary for the warped reheating scenario in a two-throat geometry. We study KK mode wavefunctions of the full two-throat system in the Randall--Sundrum (RS) approximation and find an interesting subtlety in the calculation of the KK mode tunnelling rate. While wavepacket tunnelling is suppressed unless the Standard Model throat is very long, wavefunctions of modes localized in different throats have a non-zero overlap and energy can be transferred between the throats by interactions between such KK modes. The corresponding decay rates are calculated and found to be faster than the tunnelling rates found in previously published works. However, it turns out that the imaginary parts of the mode frequencies, induced by the decay, slow the decay rates themselves down. The self-consistent decay rate turns out to be given by the plane wave tunnelling rate considered previously in the literature. We then discuss mechanisms that may enhance the energy transfer between the throats over the RS rates. In particular, we study models in which the warp factor changes in the UV region less abruptly than in the RS model, and find that it is easy to build phenomenological models in which the plane wave tunnelling rate, and hence the KK mode interaction rates, are enhanced compared to the standard RS setup.Comment: 27 pages + appendices, 5 figures, latex. v2: Discussion of decay in Section 4 changed: the most dangerous graviton amplitudes are zero, the results are now more positive for the warped reheating scenario; typos fixed, discussion cleaned up. v3:corrections in Section 5 (decay rates slowed down), mild changes of overall conclusion

MATHEMATICAL FORMULAS FOR CALCULATING NET RETURNS FROM PARTICIPATION IN GOVERNMENT PROGRAMS, CRP, AND CROP INSURANCE ALTERNATIVES

The purpose of this report is to provide a revised version of the publication, "Mathematical Formulas for Calculating Net Returns from Participation in Government Commodity Programs including Marketing Loans" (Williams and Barnaby, 1994). The change in design of the government commodity programs and development of several crop insurance alternatives has been significant since the previous paper was published. The formulas for calculating net returns incorporate provisions from the Farm Security and Rural Investment Act of 2002 and several crop insurance designs developed in the 1990s. Individuals conducting research or education programs will be able to use this revision for reference when estimating net returns for producers under current commodity program and crop insurance plan provisions.Agricultural Finance,