Causal vs. Noncausal Description of Nonlinear Wave Mixing; Resolving the Damping-Sign Controversy

Frequency-domain nonlinear wave mixing processes may be described either using response functions whereby the signal is generated after all interactions with the incoming fields, or in terms of scattering amplitudes where all fields are treated symetrically with no specific time ordering. Closed Green's function expressions derived for the two types of signals have different analytical properties. The recent controversy regarding the sign of radiative damping in the linear (Kramers Heisenberg) formula is put in a broader context

Improved Simulation of the Mass Charging for ASTROD I

The electrostatic charging of the test mass in ASTROD I (Astrodynamical Space Test of Relativity using Optical Devices I) mission can affect the quality of the science data as a result of spurious Coulomb and Lorentz forces. To estimate the size of the resultant disturbances, credible predictions of charging rates and the charging noise are required. Using the GEANT4 software toolkit, we present a detailed Monte Carlo simulation of the ASTROD I test mass charging due to exposure of the spacecraft to galactic cosmic-ray (GCR) protons and alpha particles (3He, 4He) in the space environment. A positive charging rate of 33.3 e+/s at solar minimum is obtained. This figure reduces by 50% at solar maximum. Based on this charging rate and factoring in the contribution of minor cosmic-ray components, we calculate the acceleration noise and stiffness associated with charging. We conclude that the acceleration noise arising from Coulomb and Lorentz effects are well below the ASTROD I acceleration noise limit at 0.1 mHz both at solar minimum and maximum. The coherent Fourier components due to charging are investigated, it needs to be studied carefully in order to ensure that these do not compromise the quality of science data in the ASTROD I mission.Comment: 20 pages, 14 figures, submitted to International Journal of Modern Physics

Piman Song Syntax: Its Historical Significance

Proceedings of the Seventh Annual Meeting of the Berkeley Linguistics Society (1981), pp. 275-28

Esselen Structural Prehistory

Proceedings of the Eighth Annual Meeting of the Berkeley Linguistics Society (1982

Biological Survey Report for the Calypso Natural Gas Pipeline: Shore Approach Route North of Port Everglades Entrance Channel with Landing South of Port Everglades Entrance Channel

The Calypso Natural Gas Pipeline Project (project) will include a 24-inch pipeline which will extend from the Exclusive Economic Zone (EEZ) off the southeast Florida coastline to a shore approach at Port Everglades in Fort Lauderdale, Florida. This report, which was commissioned in May 2001 and completed in July, 2001, documents the results of a detailed biological survey of underwater marine habitats from 5 to 200 feet water depth for the pipeline route. The route, which was established based on the subsea survey that was completed in May 2001 by Williamson & Associates, Inc., includes a shore approach from the north of the Port Everglades entrance channel to a pipeline landing site south of the Port Everglades entrance channel. The purpose of this biological survey report was to identify benthic characteristics within the nearshore pipeline corridor and to identify and evaluate potential temporary impacts to the marine ecosystems. The pipeline corridor investigated was 300 feet wide and extended from the shoreline to the 200 foot water depth, a distance of approximately 14,000 feet. In addition, some video surveying was conducted to approximately the 250-foot depth contour (an additional distance of approximately 500 feet). Underwater survey methods included use of SCUBA diving to conduct underwater quantitative biological transects and integrated video mapping using a vessel towed system which provided a permanent record together with a DGPS location. Remote sensing information included use of aerial photographs and LIDAR bathymetry to guide habitat delineation. A total of eight (8) benthic habitats were defined within the pipeline corridor. These habitats included: 1. First Reef 2. Submerged Breakwater/Spoil 3. Second Reef 4. Second Reef-Sand Complex 5. Sand 6. Third Reef 7. Third Reef-Sand Complex, and 8. Third Reef Transitional. Density (number per m2) of hard corals, soft corals, and sponges was determined at several representative transects within certain habitats. Results of the study indicated that overall coverage by hard corals, soft corals, and sponges is very low in the proposed project area. Along the proposed pipeline route, percent hard coral coverage ranged from 0.16% in the Submerged Breakwater / Spoil Area to 1.34% in the Third Reef habitat. Soft coral density was lowest in Second Reef-Sand Complex (0.02 soft corals per m2) and highest at the Third Reef (11.85 soft corals per m2). Sponge density varied from 0.23 sponges per m2 in the Submerged Breakwater / Spoil Area to 19.48 sponges per m2in the Second Reef zone. Previous surveys in the general project vicinity indicate that no zooxanthellate reef-building hard corals occur in water depths greater than about 120 feet of seawater (FSW). Direct impacts of approximately 1.60 acres of hardbottom habitat characterized by very low coverage by hard corals, sponges and soft corals are expected. These impacts will occur at proposed horizontal directional drilling exit or entrance holes, laydown areas of pipeline, trenching, and blanketing to bury pipeline from the Port Everglades entrance channel from the shoreline to the 200-foot depth contour, as shown in Tables 5, 6, and 7. A further approximately 4.34 acres of area would be affected adversely by temporary indirect effects (i.e., sedimentation and turbidity) effects as shown in Tables 8, 9, and 10. Table 11 provides a summary total that 5.94 acres of hardbottom habitat would be directly or indirectly affected. In addition, approximately 0.008 acres of very sparse seagrass (Halophila decipiens) will be directly impacted. Finally, no threatened or endangered species (including the federally threatened seagrass Halophila johnsonii) were observed in the project area. Observations were conducted to the approximate 250-foot depth contour. Video surveys to that depth indicated benthic conditions consistent with those of the Third Reef Transitional complex and open sand. Project activities beyond 200 FSW will consist only of pipe placement directly on the sea bottom

Alternative Stacking Sequences in Hexagonal Boron Nitride

The relative orientation of successive sheets, i.e. the stacking sequence, in layered two-dimensional materials is central to the electronic, thermal, and mechanical properties of the material. Often different stacking sequences have comparable cohesive energy, leading to alternative stable crystal structures. Here we theoretically and experimentally explore different stacking sequences in the van der Waals bonded material hexagonal boron nitride (h-BN). We examine the total energy, electronic bandgap, and dielectric response tensor for five distinct high symmetry stacking sequences for both bulk and bilayer forms of h-BN. Two sequences, the generally assumed AA' sequence and the relatively unknown (for h-BN) AB (Bernal) sequence, are predicted to have comparably low energy. We present a scalable modified chemical vapor deposition method that produces large flakes of virtually pure AB stacked h-BN; this new material complements the generally available AA' stacked h-BN

Relationship of Transmural Variations in Myofiber Contractility to Left Ventricular Ejection Fraction: Implications for Modeling Heart Failure Phenotype With Preserved Ejection Fraction

The pathophysiological mechanisms underlying preserved left ventricular (LV) ejection fraction (EF) in patients with heart failure and preserved ejection fraction (HFpEF) remain incompletely understood. We hypothesized that transmural variations in myofiber contractility with existence of subendocardial dysfunction and compensatory increased subepicardial contractility may underlie preservation of LVEF in patients with HFpEF. We quantified alterations in myocardial function in a mathematical model of the human LV that is based on the finite element method. The fiber-reinforced material formulation of the myocardium included passive and active properties. The passive material properties were determined such that the diastolic pressure-volume behavior of the LV was similar to that shown in published clinical studies of pressure-volume curves. To examine changes in active properties, we considered six scenarios: (1) normal properties throughout the LV wall; (2) decreased myocardial contractility in the subendocardium; (3) increased myocardial contractility in the subepicardium; (4) myocardial contractility decreased equally in all layers, (5) myocardial contractility decreased in the midmyocardium and subepicardium, (6) myocardial contractility decreased in the subepicardium. Our results indicate that decreased subendocardial contractility reduced LVEF from 53.2 to 40.5%. Increased contractility in the subepicardium recovered LVEF from 40.5 to 53.2%. Decreased contractility transmurally reduced LVEF and could not be recovered if subepicardial and midmyocardial contractility remained depressed. The computational results simulating the effects of transmural alterations in the ventricular tissue replicate the phenotypic patterns of LV dysfunction observed in clinical practice. In particular, data for LVEF, strain and displacement are consistent with previous clinical observations in patients with HFpEF, and substantiate the hypothesis that increased subepicardial contractility may compensate for subendocardial dysfunction and play a vital role in maintaining LVEF

17β-Estradiol dysregulates innate immune responses to Pseudomonas aeruginosa respiratory infection and is modulated by estrogen receptor antagonism

ABSTRACT Females have a more severe clinical course than males in terms of several inflammatory lung conditions. Notably, females with cystic fibrosis (CF) suffer worse outcomes, particularly in the setting of Pseudomonas aeruginosa infection. Sex hormones have been implicated in experimental and clinical studies; however, immune mechanisms responsible for this sex-based disparity are unknown and the specific sex hormone target for therapeutic manipulation has not been identified. The objective of this study was to assess mechanisms behind the impact of female sex hormones on host immune responses to P. aeruginosa . We used wild-type and CF mice, which we hormone manipulated, inoculated with P. aeruginosa , and then examined for outcomes and inflammatory responses. Neutrophils isolated from mice and human subjects were tested for responses to P. aeruginosa . We found that female mice inoculated with P. aeruginosa died earlier and showed slower bacterial clearance than males ( P &lt; 0.0001). Ovariectomized females supplemented with 17β-estradiol succumbed to P. aeruginosa challenge earlier than progesterone- or vehicle-supplemented mice ( P = 0.0003). 17β-Estradiol-treated ovariectomized female mice demonstrated increased lung levels of inflammatory cytokines, and when rendered neutropenic the mortality difference was abrogated. Neutrophils treated with 17β-estradiol demonstrated an enhanced oxidative burst but decreased P. aeruginosa killing and earlier cell necrosis. The estrogen receptor (ER) antagonist ICI 182,780 improved survival in female mice infected with P. aeruginosa and restored neutrophil function. We concluded that ER antagonism rescues estrogen-mediated neutrophil dysfunction and improves survival in response to P. aeruginosa . ER-mediated processes may explain the sex-based mortality gap in CF and other inflammatory lung illnesses, and the ER blockade represents a rational therapeutic strategy. </jats:p

Flexible Lipid Bilayers in Implicit Solvent

A minimalist simulation model for lipid bilayers is presented. Each lipid is represented by a flexible chain of beads in implicit solvent. The hydrophobic effect is mimicked through an intermolecular pair potential localized at the ``water''/hydrocarbon tail interface. This potential guarantees realistic interfacial tensions for lipids in a bilayer geometry. Lipids self assemble into bilayer structures that display fluidity and elastic properties consistent with experimental model membrane systems. Varying molecular flexibility allows for tuning of elastic moduli and area/molecule over a range of values seen in experimental systems.Comment: 5 pages, 5 figure