3,542 research outputs found
Study of the Barringer Refractor Plate Correlation Spectrometer as a remote sensing instrument
Barringer refractor plate correlation spectrometer as remote sensing instrument of pollutant gases in atmospher
Hypervelocity impacts into stainless-steel tubes armored with reinforced beryllium
Hypervelocity impact into stainless steel tubes armored with reinforced berylliu
Solar-radiation-induced damage to optical properties of ZnO-type pigments Technical summary report, Jul. 1966 - Feb. 1968
Mechanisms of solar radiation damage to optical properties in zinc oxide pigments in visible and infrared region
Hypervelocity impact damage characteristics in beryllium and graphite plates and tubes
Hypervelocity impact damage characteristics in beryllium and graphite plates and tube
Phase Closure Nulling: results from the 2009 campaign
We present here a new observational technique, Phase Closure Nulling (PCN),
which has the potential to obtain very high contrast detection and spectroscopy
of faint companions to bright stars. PCN consists in measuring closure phases
of fully resolved objects with a baseline triplet where one of the baselines
crosses a null of the object visibility function. For scenes dominated by the
presence of a stellar disk, the correlated flux of the star around nulls is
essentially canceled out, and in these regions the signature of fainter,
unresolved, scene object(s) dominates the imaginary part of the visibility in
particular the closure phase. We present here the basics of the PCN method, the
initial proof-of-concept observation, the envisioned science cases and report
about the first observing campaign made on VLTI/AMBER and CHARA/MIRC using this
technique.Comment: To be published in the proceedings of the SPIE'2010 conference on
"Optical and Infrared Interferometry II
Strong Near-Infrared Emission Interior to the Dust-Sublimation Radius of Young Stellar Objects MWC275 and AB Aur
Using the longest optical-interferometeric baselines currently available, we
have detected strong near-infrared (NIR) emission from inside the
dust-destruction radius of Herbig Ae stars MWC275 and AB Aur. Our
sub-milli-arcsecond resolution observations unambiguously place the emission
between the dust-destruction radius and the magnetospheric co-rotation radius.
We argue that this new component corresponds to hot gas inside the
dust-sublimation radius, confirming recent claims based on spectrally-resolved
interferometry and dust evaporation front modeling.Comment: 12 pages, 4 figures, Accepted for publication in ApJ
The effect of prolonged simulated non- gravitational environment on mineral balance in the adult male, volume 1 Final report
Effect of prolonged bed rest with simulated weightlessness on mineral balance in male adult - Vol.
Pressure Driven Flow of Polymer Solutions in Nanoscale Slit Pores
Polymer solutions subject to pressure driven flow and in nanoscale slit pores
are systematically investigated using the dissipative particle dynamics
approach. We investigated the effect of molecular weight, polymer concentration
and flow rate on the profiles across the channel of the fluid and polymer
velocities, polymers density, and the three components of the polymers radius
of gyration. We found that the mean streaming fluid velocity decreases as the
polymer molecular weight or/and polymer concentration is increased, and that
the deviation of the velocity profile from the parabolic profile is accentuated
with increase in polymer molecular weight or concentration. We also found that
the distribution of polymers conformation is highly anisotropic and non-uniform
across the channel. The polymer density profile is also found to be
non-uniform, exhibiting a local minimum in the center-plane followed by two
symmetric peaks. We found a migration of the polymer chains either from or
towards the walls. For relatively long chains, as compared to the thickness of
the slit, a migration towards the walls is observed. However, for relatively
short chains, a migration away from the walls is observed.Comment: 11 pages, 13 figure
Bacterial evolution: Resistance is a numbers game
Plasmids are well known for spreading antibiotic-resistance genes between bacterial strains. Recent experiments show that they can also act as catalysts for evolutionary innovation, promoting rapid evolution of novel antibiotic resistance
Disentangling the effect of growth from development in size‐related trait scaling relationships
In plant ecology, the terms growth and development are often used interchangeably. Yet these constitute two distinct processes. Plant architectural traits (e.g. number of successive forks) can estimate development stages. Here, we show the importance of including the effect of development stages to better understand size‐related trait scaling relationships (i.e. between height and stem diameter). We focused on one common savanna woody species (Senegalia nigrescens) from the Greater Kruger Area, South Africa. We sampled 406 individuals that experience different exposure to herbivory, from which we collected four traits: plant height, basal stem diameter, number of successive forks (proxy for development stage), and resprouting. We analysed trait relationships (using standardized major axis regression) between height and stem diameter, accounting for the effect of ontogeny, exposure to herbivory, and resprouting. The number of successive forks affects the scaling relationship between height and stem diameter, with the slope and strength of the relationship declining in more developed individuals. Herbivory exposure and resprouting do not affect the overall height–diameter relationship. However, when height and stem diameter were regressed separately against number of successive forks, herbivory exposure and resprouting had an effect. For example, resprouting individuals allocate more biomass to both primary and secondary growth than non‐resprouting plants in more disturbed conditions. We stress the need to include traits related to ontogeny so as to disentangle the effect of biomass allocation to primary and secondary growth from that of development in plant functional relationships
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