31,704 research outputs found
Evaluating the psychometric properties of the multigroup ethnic identity measure (MEIM) within the United Kingdom
In the present study, we examined the psychometric properties of the Multigroup Ethnic Identity Measure (MEIM) (Phinney, 1992; Phinney & Alipuria, 1990) among an ethnically diverse sample within the United Kingdom. In initial analyses, we evaluated the goodness-of-fit of a one-factor model (i.e., global ethnic identity) and the goodness-of-fit of a two-factor model (i.e., correlated but distinct Exploration and Commitment components). Results of initial confirmatory factor analyses led us to reject both the one-factor and two-factor models. Results of subsequent exploratory and confirmatory factor analyses revealed a three-factor structure (i.e., correlated but distinct Behavioral, Cognitive, and Affective components of ethnic identity) among the sample as a whole (n = 234) and among Asian Indian persons (n = 88) in particular, though resulst were mixed among White U.K./Irish persons (n = 54) in particular. Implications for the study of ethnicity-related concepts in the incerasibgly multi-cultural U.K. are discussed
Temperature dependence of the phonon entropy of vanadium
The phonon density-of-states (DOS) of elemental vanadium was measured at elevated temperatures by inelastic neutron scattering. The phonon softening predicted by thermal expansion against the bulk modulus is much larger than the measured shifts in phonon energies. We conclude that the phonon anharmonicities associated with thermal expansion are largely canceled by effects from phonon-phonon scattering. Prior measurements of the heat capacity and calculations of the electronic entropy of vanadium are assessed, and consistency requires an explicit temperature dependence of the phonon DOS. Using data from the literature, similar results are found for chromium, niobium, titanium, and zirconium
Are there any good digraph width measures?
Several different measures for digraph width have appeared in the last few
years. However, none of them shares all the "nice" properties of treewidth:
First, being \emph{algorithmically useful} i.e. admitting polynomial-time
algorithms for all \MS1-definable problems on digraphs of bounded width. And,
second, having nice \emph{structural properties} i.e. being monotone under
taking subdigraphs and some form of arc contractions. As for the former,
(undirected) \MS1 seems to be the least common denominator of all reasonably
expressive logical languages on digraphs that can speak about the edge/arc
relation on the vertex set.The latter property is a necessary condition for a
width measure to be characterizable by some version of the cops-and-robber game
characterizing the ordinary treewidth. Our main result is that \emph{any
reasonable} algorithmically useful and structurally nice digraph measure cannot
be substantially different from the treewidth of the underlying undirected
graph. Moreover, we introduce \emph{directed topological minors} and argue that
they are the weakest useful notion of minors for digraphs
High-Redshift Superclustering of QSO Absorption Line Systems on 100 Mpc Scales
We have analyzed the clustering of C IV absorption line systems in an
extensive new catalog of heavy element QSO absorbers. The catalog permits
exploration of clustering over a large range in both scale (from about 1 to
over 300 Mpc) and redshift (z from 1.2 to 4.5). We find significant evidence
(5.0 sigma) that C IV absorbers are clustered on comoving scales of 100 Mpc and
less --- similar to the size of voids and walls found in galaxy redshift
surveys of the local universe --- with a mean correlation function over these scales. We find, on these scales, that the mean
correlation function at low (z=1.7), medium (z=2.4), and high redshift (z=3.0)
is , , and , respectively.
Thus, the superclustering is present even at high redshift; furthermore, it
does not appear that the superclustering scale, in comoving coordinates, has
changed significantly since then. We find 7 QSOs with rich groups of absorbers
(potential superclusters) that account for a significant portion of the
clustering signal, with 2 at redshift . We find that the
superclustering is just as evident if we take instead of 0.5;
however, the inferred scale of clustering is then 240 Mpc , which is larger
than the largest scales of clustering known at present. This discrepancy may be
indicative of a larger value of , and hence . The evolution of
the correlation function on 50 Mpc scales is consistent with that expected in
cosmologies with density parameter ranging from 0.1 to 1.
Finally, we find no evidence for clustering on scales greater than 100 Mpc
() or 240 Mpc ().Comment: 16 LaTeX pages with 3 encapsulated Postscript figures included, uses
AASTeX (v. 4.0) available at ftp://ftp.aas.org/pubs/ , to appear in The
Astrophysical Journal Letter
Synchronizing Sequencing Software to a Live Drummer
Copyright 2013 Massachusetts Institute of Technology. MIT allows authors to archive published versions of their articles after an embargo period. The article is available at
A review of modular strategies and architecture within manufacturing operations
This paper reviews existing modularity and modularization literature within manufacturing operations. Its purpose is to examine the tools, techniques, and concepts relating to modular production, to draw together key issues currently dominating the literature, to assess managerial implications associated with the emerging modular paradigm, and to present an agenda for future research directions. The review is based on journal papers included in the ABI/Inform electronic database and other noteworthy research published as part of significant research programmes. The research methodology concerns reviewing existing literature to identify key modular concepts, to determine modular developments, and to present a review of significant contributions to the field. The findings indicate that the modular paradigm is being adopted in a number of manufacturing organizations. As a result a range of conceptual tools, techniques, and frameworks has emerged and the field of modular enquiry is in the process of codifying the modular lexicon and developing appropriate modular strategies commensurate with the needs of manufacturers. Modular strategies and modular architecture were identified as two key issues currently dominating the modular landscape. Based on this review, the present authors suggest that future research areas need to focus on the development and subsequent standardization of interface protocols, cross-brand module use, supply chain power, transparency, and trust. This is the first review of the modular landscape and as such provides insights into, first, the development of modularization and, second, issues relating to designing modular products and modular supply chains
Experimentally Constrained Molecular Relaxation: The case of hydrogenated amorphous silicon
We have extended our experimentally constrained molecular relaxation
technique (P. Biswas {\it et al}, Phys. Rev. B {\bf 71} 54204 (2005)) to
hydrogenated amorphous silicon: a 540-atom model with 7.4 % hydrogen and a
611-atom model with 22 % hydrogen were constructed. Starting from a random
configuration, using physically relevant constraints, {\it ab initio}
interactions and the experimental static structure factor, we construct
realistic models of hydrogenated amorphous silicon. Our models confirm the
presence of a high frequency localized band in the vibrational density of
states due to Si-H vibration that has been observed in a recent vibrational
transient grating measurements on plasma enhanced chemical vapor deposited
films of hydrogenated amorphous silicon.Comment: 13 pages, 4 figure
On the Monadic Second-Order Transduction Hierarchy
We compare classes of finite relational structures via monadic second-order
transductions. More precisely, we study the preorder where we set C \subseteq K
if, and only if, there exists a transduction {\tau} such that
C\subseteq{\tau}(K). If we only consider classes of incidence structures we can
completely describe the resulting hierarchy. It is linear of order type
{\omega}+3. Each level can be characterised in terms of a suitable variant of
tree-width. Canonical representatives of the various levels are: the class of
all trees of height n, for each n \in N, of all paths, of all trees, and of all
grids
- …