Time-dependent Kohn-Sham theory with memory

In time-dependent density-functional theory, exchange and correlation (xc) beyond the adiabatic local density approximation can be described in terms of viscoelastic stresses in the electron liquid. In the time domain, this leads to a velocity-dependent xc vector potential with a memory containing short- and long-range components. The resulting time-dependent Kohn-Sham formalism describes the dynamics of electronic systems including decoherence and relaxation. For the example of collective charge-density oscillations in a quantum well, we illustrate the xc memory effects, clarify the dissipation mechanism, and extract intersubband relaxation rates for weak and strong excitations.Comment: 4 pages, 4 figure

Photoelectron spectra of anionic sodium clusters from time-dependent density-functional theory in real-time

We calculate the excitation energies of small neutral sodium clusters in the framework of time-dependent density-functional theory. In the presented calculations, we extract these energies from the power spectra of the dipole and quadrupole signals that result from a real-time and real-space propagation. For comparison with measured photoelectron spectra, we use the ionic configurations of the corresponding single-charged anions. Our calculations clearly improve on earlier results for photoelectron spectra obtained from static Kohn-Sham eigenvalues

Non-adiabatic electron dynamics in time-dependent density-functional theory

Time-dependent density-functional theory (TDDFT) treats dynamical exchange and correlation (xc) via a single-particle potential, Vxc(r,t), defined as a nonlocal functional of the density n(r',t'). The popular adiabatic local-density approximation (ALDA) for Vxc(r,t) uses only densities at the same space-time point (r,t). To go beyond the ALDA, two local approximations have been proposed based on quantum hydrodynamics and elasticity theory: (a) using the current as basic variable (C-TDDFT) [G. Vignale, C. A. Ullrich, and S. Conti, Phys. Rev. Lett. 79, 4878 (1997)], (b) working in a co-moving Lagrangian reference frame (L-TDDFT) [I. V. Tokatly, Phys. Rev. B 71, 165105 (2005)]. This paper illustrates, compares, and analyzes both non-adiabatic theories for simple time-dependent model densities in the linear and nonlinear regime, for a broad range of time and frequency scales. C- and L-TDDFT are identical in certain limits, but in general exhibit qualitative and quantitative differences in their respective treatment of elastic and dissipative electron dynamics. In situations where the electronic density rapidly undergoes large deformations, it is found that non-adiabatic effects can become significant, causing the ALDA to break down.Comment: 15 pages, 15 figure

Understanding the connection between platelet-activating factor, a UV-induced lipid mediator of inflammation, immune suppression and skin cancer.

none2siLipid mediators of inflammation play important roles in several diseases including skin cancer, the most prevalent type of cancer found in the industrialized world. Ultraviolet (UV) radiation is a complete carcinogen and is the primary cause of skin cancer. UV radiation is also a potent immunosuppressive agent, and UV-induced immunosuppression is a well-known risk factor for skin cancer induction. An essential mediator in this process is the glyercophosphocholine 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine commonly referred to as platelet-activating factor (PAF). PAF is produced by keratinocytes in response to diverse stimuli and exerts its biological effects by binding to a single specific G-protein-coupled receptor (PAF-R) expressed on a variety of cells. This review will attempt to describe how this lipid mediator is involved in transmitting the immunosuppressive signal from the skin to the immune system, starting from its production by keratinocytes, to its role in activating mast cell migration in vivo, and to the mechanisms involved that ultimately lead to immune suppression. Recent findings related to its role in regulating DNA repair and activating epigenetic mechanisms, further pinpoint the importance of this bioactive lipid, which may serve as a critical molecular mediator that links the environment (UVB radiation) to the immune system and the epigenome.openDamiani, E; Ullrich, S.E.Damiani, Elisabetta; Ullrich, S. E

Effect of Alternative Wheat and Feed Grain Prices on Optimum Farm Plans and Income in Central South Dakota: Aurora, Brule, Charles Mix, Gregory and Jerauld Counties

The purpose of this report is to present some results of a cooperative research project between the South Dakota Agricultural Experiment Station and the Farm Production Economics Division, Economic Research Service, U. S. Department of Agriculture. This research contributes to a larger project-GP-5, Economic Problems in the Production and Marketing of Great Plains Wheat. The general objectives of the research undertaken in South Dakota were: ( 1) To provide economic data needed by farmers to make profitable adjustments in their farming systems and production practices and (2) To develop a research background for evaluating Government farm programs under varying assumptions

Mindfulness, Self-Compassion, Executive Functioning, and Stress: Exploring a Process Model in Adolescents

The association of trait mindfulness with emotional well-being has been found to be mediated by executive functioning. However, there is little empirical evidence on this process in adolescents. Therefore, this study tested these associations using an adolescent sample participating in a physical education yoga class. This study extended previous research by also including self-compassion and state mindfulness in addition to trait mindfulness. A prospective design employed a pilot yoga curriculum in a high school physical education class. Adolescents (N = 20) completed assessments of trait mindfulness and self-compassion at baseline, state mindfulness experienced during yoga classes over the 12 week physical education yoga class, and six indices of executive functioning and stress at the end of the 12 weeks. Path analysis was used to test the process model found by Short with the extensions of self-compassion and state mindfulness. Self-compassion directly predicted problems with activity level impulse control and indirectly predicted stress. When self-compassion did not predict specific executive functioning indicators, state mindfulness experienced in yoga predicted stress. This study contributes preliminary evidence that suggests further research into the unique effects of trait and state mindfulness as well as self-compassion on adolescent cognitive and affective outcomes. Results support the use of contemplative practices, such as yoga, in adolescent physical education as a strategy to boost emotion regulation processes

Effect of Alternative Wheat and Feed Grain Prices on Optimum Farm Plans and Income in Cetnral South Dakota: Brown and Spink Counties

The purpose of this report is to present some results of a cooperative research project between the South Dakota Agricultural Experiment Station and the Farm Production Economics Division, Economic Research Service, U. S. Department of Agriculture. This research contributes· to a larger project-GP-5, Economic Problems in the Production and Marketing of Great Plains Wheat. The general objectives of the research undertaken in South Dakota were: (1) to provide economic data needed by farmers to make profitable adjustments in their farming systems and production practices and (2) to develop a research background for evaluating government farm programs under varying assumptions

Effect of Alternative Wheat and Feed Grain Prices on Optimum Farm Plans and Income: Beadle, Clark, Codington, Day, Marshall and Roberts Counties

The purpose of this report is to present some results of a cooperative research project between the South Dakota Agricultural Experiment Station and the Farm Production Economics Division, Economic Research Service, U. S. Department of Agriculture. This research contributes to a larger project-GP-5, Economic Problems in the Production and Marketing of Great Plains Wheat. The general objectives of the research undertaken in South Dakota were: (1) to provide economic data needed by farmers to make profitable adjustments in their farming systems and production practices and (2) to develop a research background for evaluating government farm programs under varying assumptions

Effect of Alternative Wheat and Feed Grain Prices on Optimum Farm Plans and Income in Central South Dakota: Buffalo, Hand and Hyde Counties

The purpose of this report is to present some results of a cooperative research project between the South Dakota Agricultural Experiment Station and the Farm Production Economics Division, Economic Research Service, U. S. Department of Agriculture. This research contributes to a larger project-GP-5, Economic Problems in the Production and Marketing of Great Plains Wheat. The general objectives of the research undertaken in South Dakota were (1) To provide economic data needed by farmers to make profitable adjustments in their farming systems and production practices and (2) To develop a research background for evaluating Government farm programs under varying assumptions

Effect of Alternative Wheat and Feed Grain Prices on Optimum Farm Plans and Income in Central South Dakota: Hughes and Sully Counties

The purpose of this report is to present some results of a cooperative research project between the South Dakota Agricultural Experiment Station and the Farm Production Economics Division, Economic Research Service, U. S. Department of Agriculture. This research contributes to a larger project-GP-5, Economic Problems in the Production and Marketing of Great Plains Wheat. The general objectives of the research undertaken in South Dakota were: (1) To provide economic data needed by farmers to make profitable adjustments in their farming systems and production practices and (2) To develop a research background for evaluating Government farm programs under varying assumptions