Loop Expansion in Light-Cone ϕ4\phi^4 Field Theory

A loop expansion is implemented based on the path integral quantization of the light-cone $\phi^4$ field theory in 1+1 dimensions. The effective potential as a function of the zero-mode field $\omega$ is calculated up to two loop order and its derivative with respect to $\omega$ is used to determine the vacuum expectation value of the field $\phi$. The critical coupling constant at the spontaneous symmetry breakdown is consistent with that obtained in the ordinary instant-form field theory. The critical exponents which describe the behavior of the susceptibility and the vacuum expectation value of $\phi$ near the critical point are evaluated from the effective potential. The one loop diagrams for the connected Green's function are calculated in momentum space. The relevant equal-time correlation function is shown to be closely related.Comment: 12 pages, plain Tex, 1 table, 3 figures available from [email protected] , accepted by Phys. Rev.

Energetics of the global ocean: The role of mesoscale eddies

This article reviews the energy cycle of the global ocean circulation, focusing on the role of baroclinic mesoscale eddies. Two of the important effects of mesoscale eddies are: (i) the flattening of the slope of large-scale isopycnal surfaces by the eddy-induced overturning circulation, the basis for the Gent–McWilliams parametrization; and (ii) the vertical redistribution of the momentum of basic geostrophic currents by the eddy-induced form stress (the residual effect of pressure perturbations), the basis for the Greatbatch–Lamb parametrization. While only point (i) can be explained using the classical Lorenz energy diagram, both (i) and (ii) can be explained using the modified energy diagram of Bleck as in the following energy cycle. Wind forcing provides an input to the mean KE, which is then transferred to the available potential energy (APE) of the large-scale field by the wind-induced Ekman flow. Subsequently, the APE is extracted by the eddy-induced overturning circulation to feed the mean KE, indicating the enhancement of the vertical shear of the basic current. Meanwhile, the vertical shear of the basic current is relaxed by the eddy-induced form stress, taking the mean KE to endow the eddy field with an energy cascade. The above energy cycle is useful for understanding the dynamics of the Antarctic Circumpolar Current. On the other hand, while the source of the eddy field energy has become clearer, identifying the sink and flux of the eddy field energy in both physical and spectral space remains major challenges of present-day oceanography. A recent study using a combination of models, satellite altimetry, and climatological hydrographic data shows that the western boundary acts as a “graveyard” for the westward-propagating eddies

FACTORS INFLUENCING CHANGES IN POTATO AND POTATO SUBSTITUTE DEMAND

Despite the rapid rise in complex carbohydrate consumption over the last twenty-five years, fresh potato consumption has fallen by over 50%. Fresh potato growers and retailers alike need to know whether these changes reflect consumer responses to changing relative prices or incomes, or whether they are due to changes in consumer tastes. This paper uses a linear approximation almost ideal demand system (LA/AIDS) to investigate the effect of relative prices, expenditures, and a set of socioeconomic variables on complex carbohydrate demand. Estimation results show that the socioeconomic variables explain some of the changes in demand, but a significant amount remains as evidence of a change in consumer tastes.Demand and Price Analysis,

Effective Medium Theory of Filamentous Triangular Lattice

We present an effective medium theory that includes bending as well as stretching forces, and we use it to calculate mechanical response of a diluted filamentous triangular lattice. In this lattice, bonds are central-force springs, and there are bending forces between neighboring bonds on the same filament. We investigate the diluted lattice in which each bond is present with a probability $p$. We find a rigidity threshold $p_b$ which has the same value for all positive bending rigidity and a crossover characterizing bending-, stretching-, and bend-stretch coupled elastic regimes controlled by the central-force rigidity percolation point at $p_{\textrm{CF}} \simeq 2/3$ of the lattice when fiber bending rigidity vanishes.Comment: 15 pages, 9 figure

Shear wave generation using a spiral electromagnetic acoustic transducer

A spiral electromagnetic acoustic transducer (EMAT) is efficient in eddy current generation and has been used for surface defect inspection using Rayleigh waves or thickness gauging based on plane waves in echo mode. Measured and calculated particle velocities and directivities are presented. It is found that the shear wave is not predominantly a plane wave. It has zero amplitude on the axis of the generation EMAT and has maximum amplitude at the critical angle. The shear wave could be used in the steel industry for both internal and surface defect inspections together with Rayleigh wave

Predicting Convection Configurations in Coupled Fluid-Porous Systems

A ubiquitous arrangement in nature is a free-flowing fluid coupled to a porous medium, for example a river or lake lying above a porous bed. Depending on the environmental conditions, thermal convection can occur and may be confined to the clear fluid region, forming shallow convection cells, or it can penetrate into the porous medium, forming deep cells. Here, we combine three complementary approaches - linear stability analysis, fully nonlinear numerical simulations and a coarse-grained model - to determine the circumstances that lead to each configuration. the coarse-grained model yields an explicit formula for the transition between deep and shallow convection in the physically relevant limit of small Darcy number. Near the onset of convection, all three of the approaches agree, validating the predictive capability of the explicit formula. the numerical simulations extend these results into the strongly nonlinear regime, revealing novel hybrid configurations in which the flow exhibits a dynamic shift from shallow to deep convection. This hybrid shallow-to-deep convection begins with small, random initial data, progresses through a metastable shallow state and arrives at the preferred steady state of deep convection. We construct a phase diagram that incorporates information from all three approaches and depicts the regions in parameter space that give rise to each convective state

Femtosecond Laser Backside Ablation of Gold Film on Silicon Substrate

Citation: Lei, S., Grojo, D., Ma, J., Yu, X., & Wu, H. (2016). Femtosecond Laser Backside Ablation of Gold Film on Silicon Substrate. Procedia Manufacturing, 5, 594-608. doi:10.1016/j.promfg.2016.08.049Femtosecond laser ablation of gold thin film on the front and backside of silicon substrate is investigated, with backside ablation being the focus and front side ablation for comparison. The experiments are performed using 100 fs pulses delivered through an ultrafast laser source combined with an OPA for wavelength conversion at 1300 nm. We create a single shot ablation matrix by varying focus position and pulse energy. The laser beam is characterized using an IR imaging technique at both the front and backside of the substrate. It is found that the pulse profile experiences little distortion after passing though the 1 mm silicon substrate, despite the high pulse energy used. However, a comparison of the front and back ablation site indicates significant attenuation of pulse energy due to nonlinear absorption. Two types of damage happen depending on laser fluence: ablation and burst. Burst damage is confirmed with finite element simulation. © 2016 The Author

Integrating Healthcare Ethical Issues Into IS Education

Federal initiatives are encouraging the increase of IS graduates to work in the healthcare environment because they possess knowledge of datasets and dataset management that are key to effective management of electronic health records (EHRs) and health information technology (IT). IS graduates will be members of the healthcare team, and as such, they should gain an understanding of bioethics and \u27level the playing field\u27 so that they may meaningfully contribute to the healthcare team. Moreover, they should be mindful of professional ethical codes and common ground that healthcare and IS professions share, particularly with regard to ethical principles of beneficence, autonomy, fidelity, and justice. The purpose of this paper is to present ways to integrate healthcare ethical issues within IS education. To this end, we discuss the notion of a mutual understanding of bioethics and present professional codes of ethics as an advance organizer. We also offer an example ( Fidelity and The Case of Two Datasets ) that may be used in class to illustrate a specific IS healthcare ethical dilemma. Prepared with the knowledge of ethical problems in healthcare organizations, IS professionals can meaningfully contribute to the deliberations and resolutions of the problems that will emerge as more healthcare facilities employ EHRs