LDRD final report on carbon nanotube composites

Carbon nanotubes and their composites were examined using computational and experimental techniques in order to modify the mechanical and electrical properties of resins. Single walled nanotubes were the focus of the first year effort; however, sufficient quantities of high purity single walled nanotubes could not be obtained for mechanical property investigations. The unusually high electrical conductivity of composites loaded with <1% of multiwalled nanotubes is useful, and is the focus of continuing, externally funded, research

History of Deer Herd Reduction for Tick Control on Maine’s Offshore Islands

The incidence of Lyme disease in Maine is associated with high abundance of blacklegged (deer) ticks, which in turn has been partly attributed to local overabundance of white-tailed deer. With evidence from Monhegan Island that the complete removal of deer reduced ticks and risk of contracting Lyme disease, nine other offshore communities initiated efforts to cull deer. We reviewed and summarized available histories of deer management on Maine’s offshore islands. Concern about Lyme disease provided the overarching impetus for deer culls. Culls mostly occurred on islands that have no regular firearms hunting season, island communities have been challenged to control deer numbers, and social acceptance of deer culls varied. Integrated tick management (ITM) is the key to controlling ticks, but statewide ITM policy is lacking. Formation of vector control districts with statewide ITM policy would support all communities in Maine

The Origin of the Dust Arch in the Halo of NGC 4631: An Expanding Superbubble?

We study the nature and the origin of the dust arch in the halo of the edge-on galaxy NGC 4631 detected by Neininger & Dumke (1999). We present CO observations made using the new On-The-Fly mapping mode with the FCRAO 14m telescope, and find no evidence for CO emission associated with the dust arch. Our examination of previously published HI data shows that if previous assumptions about the dust temperature and gas/dust ratio are correct, then there must be molecular gas associated with the arch, below our detection threshold. If this is true, then the molecular mass associated with the dust arch is between 1.5 x 10^8 M(sun)and 9.7 x 10^8 M(sun), and likely towards the low end of the range. A consequence of this is that the maximum allowed value for the CO-to-H_2 conversion factor is 6.5 times the Galactic value, but most likely closer to the Galactic value. The kinematics of the HI apparently associated with the dust arch reveal that the gas here is not part of an expanding shell or outflow, but is instead two separate features (a tidal arm and a plume of HI sticking out into the halo) which are seen projected together and appear as a shell. Thus there is no connection between the dust "arch" and the hot X-ray emitting gas that appears to surround the galaxy Wang et al. (2001).Comment: 14 pages, including 4 figures. Accepted by A.J. for March 200

Near-field interactions between metal nanoparticle surface plasmons and molecular excitons in thin-films: part I: absorption

In this and the following paper (parts I and II, respectively), we systematically study the interactions between surface plasmons of metal nanoparticles (NPs) with excitons in thin-films of organic media. In an effort to exclusively probe near-field interactions, we utilize spherical Ag NPs in a size-regime where far-field light scattering is negligibly small compared to absorption. In part I, we discuss the effect of the presence of these Ag NPs on the absorption of the embedding medium by means of experiment, numerical simulations, and analytical calculations, all shown to be in good agreement. We observe absorption enhancement in the embedding medium due to the Ag NPs with a strong dependence on the medium permittivity, the spectral position relative to the surface plasmon resonance frequency, and the thickness of the organic layer. By introducing a low index spacer layer between the NPs and the organic medium, this absorption enhancement is experimentally confirmed to be a near field effect In part II, we probe the impact of the Ag NPs on the emission of organic molecules by time-resolved and steady-state photoluminescence measurements

Inhaler technique mastery and maintenance in healthcare professionals trained on different devices

Peer reviewedPostprin

A dust component 2 kpc above the plane in NGC 891

The halo of NGC 891 has been the subject of studies for more than a decade. One of its most striking features is the large asymmetry in H$\alpha$ emission. In this letter, we will take a quantitative look at this asymmetry at different wavelengths for the first time. We suggest that NGC 891 is intrinsically almost symmetric and the large asymmetry in H$\alpha$ emission is mostly due to dust attenuation. We will quantify the additional optical depth needed to cause the observed asymmetry in this model. By comparing large strips on the North East side of the galaxy with strips covering the same area in the South West we can quantify and analyze the asymmetry in the different wavelengths. From the 24 $\mu$m emission we find that the intrinsic asymmetry in star formation in NGC 891 is small i.e., $\sim 30$. The additional asymmetry in H$\alpha$ is modeled as additional symmetric dust attenuation which extends up to $\sim$ 40\arcsec (1.9 kpc) above the plane of the galaxy with a mid-plane value of $\tau$=0.8 and a scale height of 0.5 kpcComment: A&A in press. 5 pages, 3 figure

A Phase Front Instability in Periodically Forced Oscillatory Systems

Multiplicity of phase states within frequency locked bands in periodically forced oscillatory systems may give rise to front structures separating states with different phases. A new front instability is found within bands where $\omega_{forcing}/\omega_{system}=2n$ ($n>1$). Stationary fronts shifting the oscillation phase by $\pi$ lose stability below a critical forcing strength and decompose into $n$ traveling fronts each shifting the phase by $\pi/n$. The instability designates a transition from stationary two-phase patterns to traveling $n$-phase patterns

Luminous infrared galaxies as possible sources of the UHE cosmic rays

Ultra High Energy (UHE) particles coming from discrete extragalactic sources are potential candidates for EAS events above a few tens of EeV. In particular, galaxies with huge infrared luminosity triggered by collision and merging processes are possible sites of UHECR acceleration. Using the PSCz catalogue of IR galaxies we calculate a large scale anisotropy of UHE protons originating in the population of the luminous infrared galaxies (LIRGs). Small angle particle scattering in weak irregular extragalactic magnetic fields as well as deflection by regular Galactic field are taken into account. We give analytical formulae for deflection angles with included energy losses on cosmic microwave background (CMB). The hypotheses of the anisotropic and isotropic distributions of the experimental data above 40 EeV from AGASA are checked, using various statistical tests. We show that on the basis of the small scale clustering analysis there is a much better correlation of the UHECRs data below GZK cut-off with the predictions of the LIRG origin than with those of isotropy. We derive analytical formulae for a probability of a given number of doublets, triplets and quadruplets for any density distribution of independent events on the sky. The famous AGASA UHE triple event is found to be very well correlated on the sky with the brightest extragalactic infrared source within 70 Mpc - merger galaxies Arp 299 (NGC 3690 + IC 694).Comment: 17 pages, 10 figures, accepted for publ: Journal of Physics