A waiting time phenomenon for thin film equations

We prove the occurrence of a waiting time phenomenon for solutions to fourth order degenerate parabolic differential equations which model the evolution of thin films of viscous fluids. In space dimension less or equal to three, we identify a general criterion on the growth of initial data near the free boundary which guarantees that for sufficiently small times the support of strong solutions locally does not increase. It turns out that this condition only depends on the smoothness of the diffusion coefficient in its point of degeneracy. Our approach combines a new version of Stampacchia's iteration lemma with weighted energy or entropy estimates. On account of numerical experiments, we conjecture that the aforementioned growth criterion is optimal

Cosmic variance of the galaxy cluster weak lensing signal

Intrinsic variations of the projected density profiles of clusters of galaxies at fixed mass are a source of uncertainty for cluster weak lensing. We present a semi-analytical model to account for this effect, based on a combination of variations in halo concentration, ellipticity and orientation, and the presence of correlated haloes. We calibrate the parameters of our model at the 10 per cent level to match the empirical cosmic variance of cluster profiles at M_200m=10^14...10^15 h^-1 M_sol, z=0.25...0.5 in a cosmological simulation. We show that weak lensing measurements of clusters significantly underestimate mass uncertainties if intrinsic profile variations are ignored, and that our model can be used to provide correct mass likelihoods. Effects on the achievable accuracy of weak lensing cluster mass measurements are particularly strong for the most massive clusters and deep observations (with ~20 per cent uncertainty from cosmic variance alone at M_200m=10^15 h^-1 M_sol and z=0.25), but significant also under typical ground-based conditions. We show that neglecting intrinsic profile variations leads to biases in the mass-observable relation constrained with weak lensing, both for intrinsic scatter and overall scale (the latter at the 15 per cent level). These biases are in excess of the statistical errors of upcoming surveys and can be avoided if the cosmic variance of cluster profiles is accounted for.Comment: 14 pages, 6 figures; submitted to MNRA

Simultaneous dual-element analyses of refractory metals in naturally occurring matrices using resonance ionization of sputtered atoms

The combination of secondary neutral mass spectrometry (SNMS) and resonance ionization spectroscopy (RIS) has been shown to be a powerful tool for the detection of low levels of elemental impurities in solids. Drawbacks of the technique have been the laser-repetition-rate-limited, low duty cycle of the analysis and the fact that RIS schemes are limited to determinations of a single element. These problems have been addressed as part of an ongoing program to explore the usefulness of RIS/SNMS instruments for the analysis of naturally occurring samples. Efficient two-color, two-photon (1+1) resonance ionization schemes were identified for Mo and for four platinum-group elements (Ru, Os, Ir, and Re). Careful selection of the ionization schemes allowed Mo or Ru to be measured simultaneously with Re, Os, or Ir, using two tunable dye lasers and an XeCl excimer laser. Resonance frequencies could be switched easily under computer control, so that all five elements can be rapidly analyzed. In situ measurements of these elements in metal grains from five meteorites were conducted. From the analyses, estimates of the precision and the detection limit of the instrument were made. The trade-off between lower detection limits and rapid multielement RIS analyses is discussed

A transcription map of the 6p22.3 reading disability locus identifying candidate genes

BACKGROUND: Reading disability (RD) is a common syndrome with a large genetic component. Chromosome 6 has been identified in several linkage studies as playing a significant role. A more recent study identified a peak of transmission disequilibrium to marker JA04 (G72384) on chromosome 6p22.3, suggesting that a gene is located near this marker. RESULTS: In silico cloning was used to identify possible candidate genes located near the JA04 marker. The 2 million base pairs of sequence surrounding JA04 was downloaded and searched against the dbEST database to identify ESTs. In total, 623 ESTs from 80 different tissues were identified and assembled into 153 putative coding regions from 19 genes and 2 pseudogenes encoded near JA04. The identified genes were tested for their tissue specific expression by RT-PCR. CONCLUSIONS: In total, five possible candidate genes for RD and other diseases mapping to this region were identified

Spatially resolved electron energy loss spectroscopy on n-type ultrananocrystalline diamond films

The addition of nitrogen to the synthesis gas during synthesis of ultrananocrystalline-diamond (UNCD) films results in films uniquely exhibiting very high n-type electrical conductivity even at ambient temperatures. This result is due to the formation of nanowires having elongated diamond core nanostructures and a sp2-bonded C sheath surrounding the core. The work presented here provides detailed confirmation of this important result through spatially resolved-electron energy loss spectroscopy. The direct observation of nitrogen incorporated in the sheath has been enabled. The incorporation of this nitrogen provides strong support to a plausible mechanism for the n-type conduction characteristic of the UNCD films

Multiwavelength Raman spectroscopy of diamond nanowires present in n-type ultrananocrystalline films

Multiwavelength Raman spectroscopy is employed to investigate ultrananocrystalline diamond films deposited by the plasma enhanced chemical vapor deposition technique. Recently, we have shown that the addition of nitrogen in the gas source during synthesis induce the formation of diamond n-type films, exhibiting the highest electrical conductivity at ambient temperature. This point is related with the formation of elongated diamond nanostructures and the presence of sp2-bonded carbon in these films. The Raman results presented here confirm these aspects and provide a better and deeper understanding of the nature of these films and their related optical and electronic properties

Not all surveillance data are created equal—A multi‐method dynamic occupancy approach to determine rabies elimination from wildlife

1. A necessary component of elimination programmes for wildlife disease is effective surveillance. The ability to distinguish between disease freedom and non‐detection can mean the difference between a successful elimination campaign and new epizootics. Understanding the contribution of different surveillance methods helps to optimize and better allocate effort and develop more effective surveillance programmes. 2. We evaluated the probability of rabies virus elimination (disease freedom) in an enzootic area with active management using dynamic occupancy modelling of 10 years of raccoon rabies virus (RABV) surveillance data (2006–2015) collected from three states in the eastern United States. We estimated detection probability of RABV cases for each surveillance method (e.g. strange acting reports, roadkill, surveillance‐trapped animals, nuisance animals and public health samples) used by the USDA National Rabies Management Program. 3. Strange acting, found dead and public health animals were the most likely to detect RABV when it was present, and generally detectability was higher in fall– winter compared to spring–summer. Found dead animals in fall–winter had the highest detection at 0.33 (95% CI: 0.20, 0.48). Nuisance animals had the lowest detection probabilities (~0.02). 4. Areas with oral rabies vaccination (ORV) management had reduced occurrence probability compared to enzootic areas without ORV management. RABV occurrence was positively associated with deciduous and mixed forests and medium to high developed areas, which are also areas with higher raccoon (Procyon lotor) densities. By combining occupancy and detection estimates we can create a probability of elimination surface that can be updated seasonally to provide guidance on areas managed for wildlife disease. 5. Synthesis and applications. Wildlife disease surveillance is often comprised of a combination of targeted and convenience‐based methods. Using a multi‐method analytical approach allows us to compare the relative strengths of these methods, providing guidance on resource allocation for surveillance actions. Applying this multi‐method approach in conjunction with dynamic occupancy analyses better informs management decisions by understanding ecological drivers of disease occurrence

Thermoelectric power factors of nanocarbon ensembles as a function of temperature

Thermoelectric power factors of nanocarbon ensembles have been determined as a function of temperature from 400 to 1200 K. The ensembles, composed of mixtures of nanographite or disperse ultrananocrystalline diamond with B 4 C B4C , are formed into mechanically rigid compacts by reaction at 1200 K with methane gas and subsequently annealed in an argon atmosphere at temperatures up to 2500 K. The ensembles were characterized using scanning electron microscopy, Raman, x-ray diffraction, and high resolution transmission electron microscopy techniques and found to undergo profound nanostructural changes as a function of temperature while largely preserving their nanometer sizes. The power factors increase strongly both as a function of annealing temperature and of the temperature at which the measurements are carried out reaching 1 µW/K 2 ¿cm 1 µW/K2¿cm at 1200 K without showing evidence of a plateau. Density functional “molecular analog” calculations on systems based on stacked graphene sheets show that boron substitutional doping results in a lowering of the Fermi level and the creation of a large number of hole states within thermal energies of the Fermi level [P. C. Redfern, D. M. Greun, and L. A. Curtiss, Chem. Phys. Lett. 471, 264 (2009)]. We propose that enhancement of electronic configurational entropy due to the large number of boron configurations in the graphite lattice contributes to the observed thermoelectric properties of the ensembles

Diamond nanowires and the insulator-metal transition in ultrananocrystalline diamond films

Further progress in the development of the remarkable electrochemical, electron field emission, high-temperature diode, and optical properties of n-type ultrananocrystalline diamond films requires a better understanding of electron transport in this material. Of particular interest is the origin of the transition to the metallic regime observed when about 10% by volume of nitrogen has been added to the synthesis gas. Here, we present data showing that the transition to the metallic state is due to the formation of partially oriented diamond nanowires surrounded by an sp2-bonded carbon sheath. These have been characterized by scanning electron microscopy, transmission electron microscopy techniques (high-resolution mode, selected area electron diffraction, and electron-energy-loss spectroscopy), Raman spectroscopy, and small-angle neutron scattering. The nanowires are 80–100nm in length and consist of ~5nm wide and 6–10nm long segments of diamond crystallites exhibiting atomically sharp interfaces. Each nanowire is enveloped in a sheath of sp2-bonded carbon that provides the conductive path for electrons. Raman spectroscopy on the films coupled with a consideration of plasma chemical and physical processes reveals that the sheath is likely composed of a nanocarbon material resembling in some respects a polymer-like mixture of polyacetylene and polynitrile. The complex interactions governing the simultaneous growth of the diamond core and the sp2 sheath responsible for electrical conductivity are discussed as are attempts at a better theoretical understanding of the transport mechanism