Modification of supported lipid membranes by atomic force microscopy

The atomic force microscope (AFM) was used to structurally modify supported lipid bilayers in a controlled quantitative manner. By increasing the force applied by the AFM tip, lipid was removed from the scanned area, leaving a cut through the lipid bilayer. Cuts were repaired with the AFM by scanning the region with a controlled force and driving lipid back into the cut. A slow self-annealing of cuts was also observed

Titanium Nitride Films for Ultrasensitive Microresonator Detectors

Titanium nitride (TiNx) films are ideal for use in superconducting microresonator detectors because: a) the critical temperature varies with composition (0 < Tc < 5 K); b) the normal-state resistivity is large, \rho_n ~ 100 $\mu$Ohm cm, facilitating efficient photon absorption and providing a large kinetic inductance and detector responsivity; and c) TiN films are very hard and mechanically robust. Resonators using reactively sputtered TiN films show remarkably low loss (Q_i > 10^7) and have noise properties similar to resonators made using other materials, while the quasiparticle lifetimes are reasonably long, 10-200 $\mu$s. TiN microresonators should therefore reach sensitivities well below 10^-19 WHz^(-1/2).Comment: to be published in AP

Genetic Subdivision and Variation in Selfing Rates Among Central American Populations of the Mangrove Rivulus, Kryptolebias marmoratus.

We used 32 polymorphic microsatellite loci to investigate how a mixed-mating system affects population genetic structure in Central American populations (N = 243 individuals) of the killifish Kryptolebias marmoratus (mangrove rivulus), 1 of 2 of the world's only known self-fertilizing vertebrates. Results were also compared with previous microsatellite surveys of Floridian populations of this species. For several populations in Belize and Honduras, population structure and genetic differentiation were pronounced and higher than in Florida, even though the opposite trend was expected because populations in the latter region were presumably smaller and highly selfing. The deduced frequency of selfing (s) ranged from s = 0.39-0.99 across geographic locales in Central America. This heterogeneity in selfing rates was in stark contrast to Florida, where s &gt; 0.9. The frequency of outcrossing in a population (t = 1 - s) was tenuously correlated with local frequencies of males, suggesting that males are one of many factors influencing outcrossing. Observed distributions of individual heterozygosity showed good agreement with expected distributions under an equilibrium mixed-mating model, indicating that rates of selfing remained relatively constant over many generations. Overall, our results demonstrate the profound consequences of a mixed-mating system for the genetic architecture of a hermaphroditic vertebrate

Photoelectrochemical Hydrogen Evolution Using Si Microwire Arrays

Arrays of B-doped p-Si microwires, diffusion-doped with P to form a radial n+ emitter and subsequently coated with a 1.5-nm-thick discontinuous film of evaporated Pt, were used as photocathodes for H_2 evolution from water. These electrodes yielded thermodynamically based energy-conversion efficiencies >5% under 1 sun solar simulation, despite absorbing less than 50% of the above-band-gap incident photons. Analogous p-Si wire-array electrodes yielded efficiencies <0.2%, largely limited by the low photovoltage generated at the p-Si/H_2O junction

EMPHASIS/Nevada UTDEM user guide : version 1.0.

The Unstructured Time-Domain ElectroMagnetics (UTDEM) portion of the EMPHASIS suite solves Maxwell's equations using finite-element techniques on unstructured meshes. This document provides user-specific information to facilitate the use of the code for applications of interest

EMPHASIS/Nevada UTDEM user guide. Version 2.0.

The Unstructured Time-Domain ElectroMagnetics (UTDEM) portion of the EMPHASIS suite solves Maxwell's equations using finite-element techniques on unstructured meshes. This document provides user-specific information to facilitate the use of the code for applications of interest. UTDEM is a general-purpose code for solving Maxwell's equations on arbitrary, unstructured tetrahedral meshes. The geometries and the meshes thereof are limited only by the patience of the user in meshing and by the available computing resources for the solution. UTDEM solves Maxwell's equations using finite-element method (FEM) techniques on tetrahedral elements using vector, edge-conforming basis functions. EMPHASIS/Nevada Unstructured Time-Domain ElectroMagnetic Particle-In-Cell (UTDEM PIC) is a superset of the capabilities found in UTDEM. It adds the capability to simulate systems in which the effects of free charge are important and need to be treated in a self-consistent manner. This is done by integrating the equations of motion for macroparticles (a macroparticle is an object that represents a large number of real physical particles, all with the same position and momentum) being accelerated by the electromagnetic forces upon the particle (Lorentz force). The motion of these particles results in a current, which is a source for the fields in Maxwell's equations

Concurrent panel session 1: Environmental sustainability and Las Vegas

Moderator: Dr. Stan Smith, UNLV School of Life Sciences Scribe: Crystal Jackson, UNLV Department of Sociology Conference white paper & Full summary of panel session, 6 page

Green's function for gravitational waves in FRW spacetimes

A method for calculating the retarded Green's function for the gravitational wave equation in Friedmann-Roberson-Walker spacetimes, within the formalism of linearized Einstein gravity is developed. Hadamard's general solution to Cauchy's problem for second-order, linear partial differential equations is applied to the FRW gravitational wave equation. The retarded Green's function may be calculated for any FRW spacetime, with curved or flat spatial sections, for which the functional form of the Ricci scalar curvature $R$ is known. The retarded Green's function for gravitational waves propagating through a cosmological fluid composed of both radiation and dust is calculated analytically for the first time. It is also shown that for all FRW spacetimes in which the Ricci scalar curvatures does not vanish, $R \neq 0$, the Green's function violates Huygens' principle; the Green's function has support inside the light-cone due to the scatter of gravitational waves off the background curvature.Comment: 9 pages, FERMILAB-Pub-93/189-

Department of Radiation Oncology and Kimmel Cancer Center, Thomas jefferson University, The intronic G13964C variant in p53 is not a high-risk mutation in familial breast cancer in Australia.

BACKGROUND: Mutations in BRCA1 and BRCA2 account for approximately 50% of breast cancer families with more than four affected cases, whereas exonic mutations in p53, PTEN, CHK2 and ATM may account for a very small proportion. It was recently reported that an intronic variant of p53--G13964C--occurred in three out of 42 (7.1%) \u27hereditary\u27 breast cancer patients, but not in any of 171 \u27sporadic\u27 breast cancer control individuals (P = 0.0003). If this relatively frequent occurrence of G13964C in familial breast cancer and absence in control individuals were confirmed, then this would suggest that the G13964C variant plays a role in breast cancer susceptibility. METHOD: We genotyped 71 familial breast cancer patients and 143 control individuals for the G13964C variant using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) analysis. RESULTS: Three (4.2%; 95% confidence interval [CI] 0-8.9%) G13964C heterozygotes were identified. The variant was also identified in 5 out of 143 (3.5%; 95% CI 0.6-6.4%) control individuals without breast cancer or a family history of breast cancer, however, which is no different to the proportion found in familial cases (P = 0.9). CONCLUSION: The present study would have had 80% power to detect an odds ratio of 4.4, and we therefore conclude that the G13946C polymorphism is not a \u27high-risk\u27 mutation for familial breast cancer

Symptoms of depression and cardiovascular reactions to acute psychological stress: Evidence from a population study

Depression and exaggerated cardiovascular reactivity are considered risk factors for cardiovascular disease, possibly as a result of common antecedents, such as altered autonomic nervous system function. We examined the association between depressive symptomatology and cardiovascular reactions to psychological stress in 1608 adults (875 women) comprising three distinct age cohorts: 24-, 44-, and 63-year olds. Depression was assessed using the Hospital Anxiety and Depression Scale. Blood pressure and heart rate were measured at baseline and during the paced auditory serial arithmetic test. Depression scores were negatively associated with systolic blood pressure and heart rate reactions, after adjustment for likely confounders such as sex, cohort, occupational status, body mass index, stress task performance score, baseline cardiovascular activity, antidepressant and antihypertensive medication. The direction of association was opposite to that which would be expected if excessive reactivity were to mediate the association between depression and cardiovascular disease outcomes or if they shared common antecedents