932 research outputs found
Nano-scale composition of commercial white powders for development of latent fingerprints on adhesives
This is the post-print version of the article - Copyright @ 2010 Elsevier.Titanium dioxide based powders are regularly used in the development of latent fingerprints on dark surfaces. For analysis of prints on adhesive tapes, the titanium dioxide can be suspended in a surfactant and used in the form of a powder suspension. Commercially available products, whilst having nominally similar composition, show varying levels of effectiveness of print development, with some powders adhering to the background as well as the print. X-ray fluorescence (XRF), analytical transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and laser particle sizing of the fingerprint powders show TiO2 particles with a surrounding coating, tens of nanometres thick, consisting of Al and Si rich material, with traces of sodium and sulphur. Such aluminosilicates are commonly used as anti-caking agents and to aid adhesion or functionality of some fingerprint powders; however, the morphology, thickness, coverage and composition of the aluminosilicates are the primary differences between the white powder formulations and could be related to variation in the efficacy of print development.This work is part funded by the Home Office Scientific Development Branch, UK
Trends in Non-Assigned Reading by High School Seniors
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66634/2/10.1177_019263659608058417.pd
Explaining variation in nascent entrepreneurship
This
paper aims at explaining cross-country variation in nascent
entrepreneurship. Regression analysis is applied using various explanatory
variables derived from three different approaches. We make use of the
Global Entrepreneurship Monitor database, including nascent
entrepreneurship rates for 36 countries in 2002 as well as variables from
standardized national statistics. The first approach relates the level of
entrepreneurship of a country to its level of economic development. We
find evidence for a U-shaped relationship. The second approach deals with
a regime switch where the innovative advantage moves from large,
established enterprises to small and new firms, because new technologies
have reduced the importance of scale economies in many sectors. The third
approach assumes that nascent entrepreneurship partly depends upon various
non-economic conditions in the domains technology, demography, culture and
institutions, influencing opportunities, resources, skills and
preferences. Several indicators of these aggregate conditions are found to
influence nascent entrepreneurship. A full, eclectic model combining the
three approaches includes a U-shaped relationship with per capita income
as well as with Porter's innovative capacity index in addition to effects
of the total business ownership rate (+), social security expenditure (-),
the aggregate tax rate (+) and population growth (+). In the model a
'(former) centralized command economies' dummy also plays a role (-).
Finally, the paper investigates whether determinants of nascent
entrepreneurship differ for opportunity-based and necessity- based forms
of entrepreneurial activity. A U-shaped relationship with per capita
income as well as with the innovative capacity index is only found for
opportunity-based entrepreneurial activity. For economically advanced
nations striving to promote entrepreneurship, the results suggest that
improving incentive structures for entrepreneurship and promoting the
entrepreneurial exploitation of scientific findings offer a promising
approach for public policy
Explaining nascent entrepreneurship across countries
This paper aims at explaining cross-country variation in nascent entrepreneurship. Regression
analysis is applied using various explanatory variables derived from three different approaches.
We make use of the Global Entrepreneurship Monitor database, including nascent
entrepreneurship rates for 36 countries in 2002 as well as variables from standardized national
statistics. The first approach relates the level of entrepreneurship of a country to its level of
economic development. We find evidence for a U-shaped relationship. The second approach
deals with a regime switch where the innovative advantage moves from large, established
enterprises to small and new firms, because new technologies have reduced the importance of
scale economies in many sectors. The third approach assumes that nascent entrepreneurship
depends upon aggregate conditions such as technology, demography, culture and
institutions, influencing opportunities, resources, skills and preferences. Several indicators of
these aggregate conditions are found to correlate with nascent entrepreneurship. A full model
combining the three approaches includes a U-shaped relationship with per capita income as well
as with Porterâs innovative capacity index in addition to effects of social security expenditure (-)
and the total business ownership rate (+). Finally, a (former) communist-country dummy plays
an important role
Radio Source Heating in the ICM: The Example of Cygnus A
One of the most promising solutions for the cooling flow problem involves
energy injection from the central AGN. However it is still not clear how
collimated jets can heat the ICM at large scale, and very little is known
concerning the effect of radio lobe expansion as they enter into pressure
equilibrium with the surrounding cluster gas. Cygnus A is one of the best
examples of a nearby powerful radio galaxy for which the synchrotron emitting
plasma and thermal emitting intra-cluster medium can be mapped in fine detail,
and previous observations have inferred possible shock structure at the
location of the cocoon. We use new XMM-Newton observations of Cygnus A, in
combination with deep Chandra observations, to measure the temperature of the
intra-cluster medium around the expanding radio cavities. We investigate how
inflation of the cavities may relate to shock heating of the intra-cluster gas,
and whether such a mechanism is sufficient to provide enough energy to offset
cooling to the extent observed.Comment: To appear in the Proceedings of "Heating vs. Cooling in Galaxies and
Clusters of Galaxies", August 2006, Garching (Germany), Eds. H. Boehringer,
G.W. Pratt, A. Finoguenov, P. Schuecker, Springer-Verlag series "ESO
Astrophysics Symposia", p.101, in press. 8 pages, 3 multiple figure
Effects of climate change on reproduction,larval development, and adult health of coral trout (Plectropomus spp.)
Climate change is emerging as the single greatest threat to coral-reef ecosystems.The most immediate impacts will be a loss of diversity and changes to fish community composition and may lead to eventual declines in abundance and productivity of key fisheries species. A key component of this research is to assess effects of projected changes in environmental conditions (temperature and ocean acidity) due to climate change on reproduction, growth and development of coral trout (Plectropomus leopardis).Ultimately, this research will fill key knowledge gaps about climate change impacts on larger fishes, which are fundamental to optimizing resilience-based management, and in turn improve the adaptive capacity of industries and communities along the Great Barrier Reef
Nanostructure and paramagnetic centres in diamond-like carbon: Effect of Ar dilution in PECVD process
Diamond-like carbon (DLC) films were deposited utilising plasma enhanced chemical vapour deposition (PECVD) with acetylene precursor, diluted with 0 â 45% argon. Electron paramagnetic resonance (EPR) measurements show the presence of one paramagnetic centre with no change in spin population over the range of film deposition conditions. However, the EPR linewidth decreases with increasing argon content of the precursor mix, suggesting an enhancement of motional narrowing due to an increase in electron delocalization, related to an increase in the sp2 cluster size. Atomic force microscopy (AFM) measurements indicate the surface of the DLC is formed of nanoscale asperities of material. With radii of tens of nanometres for films deposited with zero argon, the size of the features increases with the argon dilution of the acetylene. Energy dispersive x-ray analysis and electrical measurements further elucidate the changes in film structure
Thinking about growth : a cognitive mapping approach to understanding small business development
School of Managemen
Exceptionally Slow Rise in Differential Reflectivity Spectra of Excitons in GaN: Effect of Excitation-induced Dephasing
Femtosecond pump-probe (PP) differential reflectivity spectroscopy (DRS) and
four-wave mixing (FWM) experiments were performed simultaneously to study the
initial temporal dynamics of the exciton line-shapes in GaN epilayers. Beats
between the A-B excitons were found \textit{only for positive time delay} in
both PP and FWM experiments. The rise time at negative time delay for the
differential reflection spectra was much slower than the FWM signal or PP
differential transmission spectroscopy (DTS) at the exciton resonance. A
numerical solution of a six band semiconductor Bloch equation model including
nonlinearities at the Hartree-Fock level shows that this slow rise in the DRS
results from excitation induced dephasing (EID), that is, the strong density
dependence of the dephasing time which changes with the laser excitation
energy.Comment: 8 figure
Nonextensivity of the cyclic Lattice Lotka Volterra model
We numerically show that the Lattice Lotka-Volterra model, when realized on a
square lattice support, gives rise to a {\it finite} production, per unit time,
of the nonextensive entropy . This finiteness only occurs for for the growth mode
(growing droplet), and for for the one (growing stripe). This
strong evidence of nonextensivity is consistent with the spontaneous emergence
of local domains of identical particles with fractal boundaries and competing
interactions. Such direct evidence is for the first time exhibited for a
many-body system which, at the mean field level, is conservative.Comment: Latex, 6 pages, 5 figure
- âŠ