292 research outputs found
Perceptions About The ISO 9000 (2000) Quality System Standard Revision And Its Value: The Dutch Experience
The aim of the research reported in this paper is to assess the relative value of the 2000 version of the ISO 9000 series of quality management system standards in comparison to the 1994 version. 773 organisations in the Netherlands which have all been certified to the ISO 9000 standard were surveyed (a response rate of 21.4%) and of these only 22 had not yet converted to the 2000 version of the standard. Amongst the major findings are an overall positive perception of the value of the ISO 9000 (2000) quality system standard and a consistently higher appreciation of the 2000 version compared to the 1994 version
Nanometre-scale optical property fluctuations in Cu2ZnSnS4 revealed by low temperature cathodoluminescence
Band tailing is a major contributing factor to the large open circuit voltage (Voc) deficit that is currently limiting Cu2ZnSnS4 (CZTS) photovoltaic devices. It occurs in highly doped, highly compensated semiconductors and gives rise to a non-uniform electronic band structure. Here we report spatially resolved fluctuations in CZTS optical properties using low temperature cathodoluminescence (CL) in a scanning electron microscope (SEM). Principal component analysis reveals three CL peaks whose relative intensity vary across domains ~ 100 nm in size. It is not known whether the non-uniform optical properties are due to changes in composition or due to structural order-disorder at constant composition. Measurement of composition with energy dispersive X-ray (EDX) analysis in an SEM and ordering with Micro-Raman mapping revealed CZTS to be uniform within the spatial resolution (estimated at ~ 0.4 µm and 1.1 µm respectively) and sensitivity of the two techniques. The CL results are consistent with the presence of band tailing in CZTS
The E-Business Research Network: summary of the results of the Dutch pilot survey
A project has been started with the intention to develop an E-Business Research Network on E-business related research in business and management. The initiative has been taken in co-operation between Erasmus University and UMIST to develop a project in which the first stage concerns the development of a database of researchers and their activities in e-business related research in business and management. The next stage will be to investigate the needs in companies in relation to e-business. It is hoped that an Internet-based database will stimulate interaction and communication between the supply and demand sides of e-business related research. This assumption is based on our previous research in Quality Management conducted in the early to mid 1990's.
This paper describes the project and also summarises the results of the first pilot questionnaire based on responses from researchers at universities in The Netherlands
Triggered Star Formation
Triggered star formation in bright rims and shells is reviewed. Shells are
commonly observed in the Milky Way and other galaxies, but most diffuse shells
seen in HI or the infrared do not have obvious triggered star formation. Dense
molecular shells and pillars around HII regions often do have such triggering,
although sometimes it is difficult to see what is triggered and what stars
formed in the gas before the pressure disturbances. Pillar regions without
clear age gradients could have their stars scattered by the gravity of the
heads. Criteria and timescales for triggering are reviewed. The insensitivity
of the average star formation rate in a galaxy to anything but the molecular
mass suggests that triggering is one of many processes that lead to
gravitational collapse and star formation.Comment: 16 pages, 4 figures, Ecole Evry Schatzman 2010: Star Formation in the
Local Universe. Lecture 4 of
The Spatial Distribution of the Young Stellar Clusters in the Star-forming Galaxy NGC 628
We present a study of the spatial distribution of the stellar cluster populations in the star-forming galaxy NGC 628. Using Hubble Space Telescope broadband WFC3/UVIS UV and optical images from the Treasury Program LEGUS (Legacy ExtraGalactic UV Survey), we have identified 1392 potential young ( Myr) stellar clusters within the galaxy using a combination of visual inspection and automatic selection. We investigate the clustering of these young stellar clusters and quantify the strength and change of clustering strength with scale using the two-point correlation function. We also investigate how image boundary conditions and dust lanes affect the observed clustering. The distribution of the clusters is well fit by a broken power law with negative exponent α. We recover a weighted mean index of for all spatial scales below the break at 3farcs3 (158 pc at a distance of 9.9 Mpc) and an index of above 158 pc for the accumulation of all cluster types. The strength of the clustering increases with decreasing age and clusters older than 40 Myr lose their clustered structure very rapidly and tend to be randomly distributed in this galaxy, whereas the mass of the star cluster has little effect on the clustering strength. This is consistent with results from other studies that the morphological hierarchy in stellar clustering resembles the same hierarchy as the turbulent interstellar medium
Interstellar MHD Turbulence and Star Formation
This chapter reviews the nature of turbulence in the Galactic interstellar
medium (ISM) and its connections to the star formation (SF) process. The ISM is
turbulent, magnetized, self-gravitating, and is subject to heating and cooling
processes that control its thermodynamic behavior. The turbulence in the warm
and hot ionized components of the ISM appears to be trans- or subsonic, and
thus to behave nearly incompressibly. However, the neutral warm and cold
components are highly compressible, as a consequence of both thermal
instability in the atomic gas and of moderately-to-strongly supersonic motions
in the roughly isothermal cold atomic and molecular components. Within this
context, we discuss: i) the production and statistical distribution of
turbulent density fluctuations in both isothermal and polytropic media; ii) the
nature of the clumps produced by thermal instability, noting that, contrary to
classical ideas, they in general accrete mass from their environment; iii) the
density-magnetic field correlation (or lack thereof) in turbulent density
fluctuations, as a consequence of the superposition of the different wave modes
in the turbulent flow; iv) the evolution of the mass-to-magnetic flux ratio
(MFR) in density fluctuations as they are built up by dynamic compressions; v)
the formation of cold, dense clouds aided by thermal instability; vi) the
expectation that star-forming molecular clouds are likely to be undergoing
global gravitational contraction, rather than being near equilibrium, and vii)
the regulation of the star formation rate (SFR) in such gravitationally
contracting clouds by stellar feedback which, rather than keeping the clouds
from collapsing, evaporates and diperses them while they collapse.Comment: 43 pages. Invited chapter for the book "Magnetic Fields in Diffuse
Media", edited by Elisabete de Gouveia dal Pino and Alex Lazarian. Revised as
per referee's recommendation
First measurement of direct photoproduction on the proton
We report on the results of the first measurement of exclusive
meson photoproduction on protons for GeV and GeV. Data were collected with the CLAS detector at the Thomas
Jefferson National Accelerator Facility. The resonance was detected via its
decay in the channel by performing a partial wave analysis of the
reaction . Clear evidence of the meson
was found in the interference between and waves at GeV. The -wave differential cross section integrated in the mass range of
the was found to be a factor of 50 smaller than the cross section
for the meson. This is the first time the meson has been
measured in a photoproduction experiment
Dense Stellar Populations: Initial Conditions
This chapter is based on four lectures given at the Cambridge N-body school
"Cambody". The material covered includes the IMF, the 6D structure of dense
clusters, residual gas expulsion and the initial binary population. It is aimed
at those needing to initialise stellar populations for a variety of purposes
(N-body experiments, stellar population synthesis).Comment: 85 pages. To appear in The Cambridge N-body Lectures, Sverre Aarseth,
Christopher Tout, Rosemary Mardling (eds), Lecture Notes in Physics Series,
Springer Verla
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