Cosmology of the Spinor Emergent Universe and Scale-invariant Perturbations

A nonsingular emergent universe cosmology can be realized by a nonconventional spinor field as first developed in \cite{Cai:2012yf}. We study the mechanisms of generating scale-invariant primordial power spectrum of curvature perturbation in the frame of spinor emergent universe cosmology. Particularly, we introduce a light scalar field of which the kinetic term couples to the bilinear of the spinor field. This kinetic coupling can give rise to an effective "Hubble radius" for primordial fluctuations from the scalar field to squeeze at large length scales as well as to form a nearly scale-invariant power spectrum. We study the stability of the backreaction and constrain the forms of the coupling terms. These almost scale-independent fluctuations are able to be transferred into curvature perturbation after the epoch of emergent universe through a generalized curvaton mechanism and thus can explain cosmological observations.Comment: 11 pages, 4 figure

Unifying temperature definition in atomistic and field representations of conservation laws

This work presents a formalism to derive field quantities and conservation laws from the atomistic using the theory of distributions as the mathematical tool. By defining temperature as a derived quantity, as that in molecular kinetic theory and atomistic simulations, a field representation of the conservation law of linear momentum is precisely derived and expressed in terms of temperature field, leading to a unified atomistic and continuum description of temperature and a new conservation equation of linear momentum that, supplemented by an interatomic potential, completely governs thermal and mechanical processes across multiple scales from the atomic to the continuum and can solve for atomistic trajectories for systems at finite temperatures, as well as the evolution of local field quantities in space and time with atomic or multiscale resolution. Four sets of numerical examples are presented to demonstrate the efficacy of the formulation in capturing the effect of temperature or thermal fluctuations, including phonon density of states, thermally activated dislocation motion, dislocation formation during heteroepitaxy, and attenuation of longitudinal acoustic waves as a result of their interaction with thermal phonons

Inducing R&D investment with price ceilings

Though government intervention is prevalent in the market for research and development (R&D), most literature has focused on the use of subsidies, patents or joint research ventures to obtain the efficient R&D investment. By using a two-stage duopoly model in which firms first choose the level of investment and then output, our paper shows that the introduction of a price ceiling by the regulator will result in the optimal level of R&D. This interesting but counterintuitive result contrasts with the existing literature and advances our understanding about price ceilings.Research and development; Subsidy; Price ceiling

Essays on Timing of Firm Actions in Industrial Economics

The timing of actions by firms plays an important role in industrial economics. It is key to strategic advantage in oligopoly models whether firms compete on quantity or on price. In a vertical relationship between input suppliers and final-good manufacturers, a firm which chooses a strategy first will take into account the response by those firms moving second and different sequence of play leads to different market outcomes. In my dissertation, I study the determinants and implications of the timing of firm actions in a variety of scenarios. In my first two essays, I examine how market leadership may arise endogenously in oligopoly models and focus on the effect of information about uncertain market demand. My first essay studies a quantity game and I identify the circumstance under which a perishable information asymmetry regarding stochastic demand causes market leadership. In an information acquisition game, I show that Stackelberg equilibrium in the full game is supported only when firms have different costs of information. My second essay considers a duopoly in which firms supply a differentiated product and compete on price. I find that different equilibrium outcomes arise under different information structures. Under asymmetric information, a firm’s information advantage leads to a strategic disadvantage of leading in the price game. The time value of information may well be negative, contrasting with results in the first essay. In my third essay, I consider a vertical relationship in which a supplier sets the price of an input and the firm that produces the final good must choose how much to invest in some complementary input or process. Two models with different sequence of firm actions are studied and yield different pricing strategies for the upstream monopolist. Interestingly, a change of the sequence from one model (the upstream firm commits to input prices first) to the other (the upstream firm sets input prices after investments are made) benefits all parties including the upstream monopolist, the downstream firms and the consumers

Genetic Diversity, Micro Propagation, and Cold Hardiness of Ilex glabra (L.) A. Gray

Ilex glabra (L.) A.Gray (inkberry) is a native evergreen shrub with dark green foliage and compact habit. This shrub has gained popularity in the northern landscapes of the United States and more nursery growers would like to produce it. To better understand genetic relationships among inkberry cultivars and breed cold-hardy cultivars for northern nursery growers and landscape specialists, the following projects were conducted. A group of 48 inkberry accessions and two other Ilex species (Ilex crenata Thunb. and I. mutchagara Makino) were studied using amplified fragment length polymorphism (AFLP) markers. A total of 229 markers between 50 and 500 base pairs (bps) were produced from eight AFLP primer combinations. Eighty-seven percent of the markers were polymorphic. The markers for each primer-pair ranged from 22 to 45 and the genetic distance ranged from 0.001 to 0.349. Within the inkberry clade, 48 accessions were classified into six groups including, a wild species group and five cultivated groups, ‘Densa’, f. leucocarpa, ‘Pretty Girl’, ‘Shamrock’ and ‘Viridis’. Within each group, the legitimacy of named cultivars and distinguished clones were discussed based on both morphological and molecular data. Inkberry was hybridized with cold-hardy male Ilex verticillata (L.) A. Gray (common winterberry) and Ilex × meserveae S.Y. Hu (meserve holly) to increase the cold hardiness. Cross pollination of inkberry and its five cultivars with both male plants was carried out in a greenhouse. Inkberry ‘Chamzin’ and ‘Densa’ had higher compatibility with either common winterberry or meserve holly, while inkberry wild species and its cultivar ‘Compacta’ were less compatible, and ‘Nigra’ and ‘Shamrock’ were almost incompatible. The pollen germination in situ observed with fluorescence microscope also supported the above results. Pollen germination of common winterberry and meserve holly on the stigma of inkberry wild species and inkberry ‘Chamzin’, ‘Compacta’, ‘Densa’ was more than that on inkberry ‘Nigra’ and ‘Shamrock’. A dramatic reduction in the number of pollen tubes was observed as they grew along the style and into ovary. The percentage of pollen tubes reaching the ovary of inkberry wild species and inkberry ‘Chamzin’, ‘Compacta’, ‘Densa’ was higher than that of inkberry ‘Nigra’ and ‘Shamrock’. Most of their fruit set were aborted and the fully developed seeds were less than 54.2% (meserve holly) and 32.4% (common winterberry). Reproduction barriers, including the inhibition of pollen germination, pollen tube growth to the style and the ovary, and lack of fertilization, resulted in the cross incompatibility of inkberry with both cold hardy species. Further cross-pollination should consider the incompatibility of cultivar variations. Nodal segments containing one axillary bud (1-1.5 cm) of inkberry were established on a Murashige and Skoog (MS) medium without hormones. The sprouted shoots (~1.0 cm) were cultured on a MS medium supplemented with BAP, KIN or ZT at 2.3, 4.5, 9.1, or 18.2 µM. After 38 days, ZT and BAP induced multiple shoot formation with multiplication rates of 4-6, while the multiplication rate of KIN was less than 2. Shoots cultured on ZT grew significantly taller than those on BAP and KIN. The height of the longest shoots treated with ZT was 4.6 cm, 1.6-2.2 times greater than those treated with BAP or KIN. Shoots (~2 cm) were subcultured on ¼ strength MS (¼ MS) medium containing either IBA or NAA at 2.6, 5.1, or 10.3 µM. Adventitious roots formed in vitro after 2-4 weeks. IBA at 10.3 µM produced the best rooting (100%) compared to other treatments after 38 days of culture. The average number of roots per shoot for IBA was about 15, 1.6-3.1 times as many as that of other treatments. All rooted plantlets were successfully transplanted. Cold hardiness tests of inkberry cultivars were conducted in both field trials and laboratory tests. A total of 72% and 93% of plants survived for 2007 and 2008 planting, respectively. ‘Shamrock’ was the most cold-hardy cultivar; f. leucocarpa, ‘Viridis’, and ‘Nigra’ were the least cold-hardy cultivars; while ‘Compacta’, ‘Densa’, ‘Chamzin’, ‘Pretty Girl’, and wild species had intermediate cold hardiness. Based on controlled freezing test of inkberry cultivars, the REC50 value of inkberry cultivars ranged from -19 to -32 ?? for Jan. 2007 and -18 to -38 ?? for Jan. 2008. The cold hardiness rate from field trials was significantly correlated with the REC50 value from laboratory tests. Laboratory test could be used to reliably predict the cold tolerance of inkberry cultivars in the field

Growth, Morphological, and Biochemical Responses of Four Native Species to Salinity Stress

Native plants are of great value in landscape maintenance. Despite their importance in the landscape, the salt tolerance of most native plants has received little attention. The present research was designed to assess morphological, physiological, and biochemical responses of four Utah-native plants [Arctostaphylos uva-ursi (kinnikinnick), Cercocarpus ledifolius (curl-leaf mountain mahogany), Cercocarpus montanus ‘Coy’ (alder-leaf mountain mahogany), and Shepherdia ×utahensis ‘Torrey’ (hybrid buffaloberry)] at different salinity levels. Each species was irrigated with a nutrient solution at an electrical conductivity (EC) of 1.2 dS·m-1 (control) or saline solutions at ECs of 5.0 or 10.0 dS·m-1 for 8 weeks. The experiment was a randomized complete block design with 10 replications. At 8 weeks after the initiation of the experiment, A. uva-ursi and C. montanus ‘Coy’ had slight foliar salt damage with an average visual score of 3.7 (0 = dead, 5 = excellent with no sign of foliar salt damage) when irrigated with saline solution at an EC of 5.0 dS·m-1 and were dead at an EC of 10.0 dS·m-1. Similarly, C. ledifolius had an average visual score of 3.2 when irrigated with saline solution at an EC of 10.0 dS·m-1. However, almost no foliar salt damage was observed on S. ×utahensis ‘Torrey’ during the experimental period. In addition, the shoot dry weight of all species was reduced with elevated salinity levels in the irrigation water. Salinity stress also reduced gas exchange rates of plants and affected their mineral content. Proline accumulated in the leaves of native plants but was species-dependent. In conclusion, S. ×utahensis ‘Torrey’ was tolerant to salinity stress followed by C. ledifolius; A. uva-ursi and C. montanus ‘Coy’ were sensitive to salinity stress