3,273 research outputs found
Restoration Design for an Urban River: Some Lessons Learned
In 1997, a project was completed on the Mad River in Waterbury, Connecticut to provide physical habitat enhancement measures in a previously altered reach of river. That project provides several lessons about the application of such restoration techniques in an urbanized setting
A New Component in the Radio Continua of PNe
A byproduct of experiments designed to map the CMB is the recent detection of a new component of foreground galactic emission. The anomalous foreground at 10–30 GHz, unexplained by traditional emission mechanisms, correlates with 100 mum dust emission, and is thus presumably due to dust.Is the anomalous foreground ubiquitous in the Galaxy? I will present evidence obtained with the CBI and SIMBA+SEST supporting the existence of the new component in the ISM at large, and in specific objects, in the form of a 31 GHz excess over free-free emission in PNe
High magnetic field superconducting properties of Nb3Sn films Final report
High magnetic field superconducting properties of niobium stannide films and shielding characterictics of stannide layer
Physical characteristics of G331.5-0.1: The luminous central region of a Giant Molecular Cloud
We report molecular line and dust continuum observations toward the high-mass
star forming region G331.5-0.1, one of the most luminous regions of massive
star-formation in the Milky Way, located at the tangent region of the Norma
spiral arm, at a distance of 7.5 kpc. Molecular emission was mapped toward the
G331.5-0.1 GMC in the CO (J=1-0) and C18O (J=1-0) lines with NANTEN, while its
central region was mapped in CS (J=2-1 and J=5-4) with SEST, and in CS (J=7-6)
and 13CO (J=3-2) with ASTE. Continuum emission mapped at 1.2 mm with SIMBA and
at 0.87 mm with LABOCA reveal the presence of six compact and luminous dust
clumps, making this source one of the most densely populated central regions of
a GMC in the Galaxy. The dust clumps are associated with molecular gas and they
have the following average properties: size of 1.6 pc, mass of 3.2x10^3 Msun,
molecular hydrogen density of 3.7x10^4 cm^{-3}, dust temperature of 32 K, and
integrated luminosity of 5.7x10^5 Lsun, consistent with values found toward
other massive star forming dust clumps. The CS and 13CO spectra show the
presence of two velocity components: a high-velocity component at ~ -89 km
s^{-1}, seen toward four of the clumps, and a low-velocity component at ~ -101
km s^{-1} seen toward the other two clumps. Radio continuum emission is present
toward four of the molecular clumps, with spectral index estimated for two of
them of 0.8+-0.2 and 1.2+-0.2. A high-velocity molecular outflow is found at
the center of the brightest clump, with a line width of 26 km s^{-1} (FWHM) in
CS (J=7-6). Observations of SiO (J=7-6 and J=8-7), and SO (J_K=8_8-7_7 and
J_K=8_7-7_6) lines provide estimates of the gas rotational temperature toward
this outflow >120 K and >75 K, respectively.Comment: 34 pages, 20 figures, 11 tables, Accepted for Publication in The
Astrophysical Journa
Measuring the notched compressive strength of composite laminates: Specimen size effects
Large fibre reinforced composite structures can give much lower strengths than small test specimens, so a proper understanding of scaling is vital for their safe and efficient use. Small size (scale) specimens are commonly tested to justify allowable stresses, but could be dangerous if results are extrapolated without accounting for scaling effects. On the other hand large factors are sometimes applied to compensate for uncertainties, resulting in overweight designs. The most important variables of scaling effects on the strength of composites with open holes have been identified from experimental tests as notch size, ply and laminate thickness. In this study, these have been scaled both independently and simultaneously over a large range of combinations. The specimens are fabricated from commercially available (Hexcel Composites Ltd.) carbon/epoxy pre-impregnated tapes 0.125 mm thick (IM7/8552). The material is laid up by hand in unidirectional [04]ns with n = 2, 3, 4, and 8 (i.e., 2, 3, 4 and 8 mm thick) and multidirectional laminates; two generic quasi-isotropic lay-ups, one fabricated with blocked plies [45n/90n/−45n/0n]s and the other with distributed layers [45/90/−45/0]ns with n = 2, 4 and 8 are examined. It is shown that the critical failure mechanism in these laminates is in the form of fibre microbuckling or kinking. The unnotched compressive strength in unidirectional specimens thicker than 2 mm is found to be limited by the stress concentration developed at the end tabs and manufacturing induced defects in the form of ply waviness, fibre misalignment and voids rather than specimen size (scaling). In the open hole specimens, for both lay-ups, the strength reduction observed is due to hole size effect rather than specimen thickness or volume increase. The open hole (notched) compressive strength results obtained compare favourably to predictions by a linear softening cohesive zone fracture model developed in earlier work by the second author
Multi-order interference is generally nonzero
It is demonstrated that the third-order interference, as obtained from
explicit solutions of Maxwell's equations for realistic models of three-slit
devices, including an idealized version of the three-slit device used in a
recent three-slit experiment with light (U. Sinha et al., Science 329, 418
(2010)), is generally nonzero. The hypothesis that the third-order interference
should be zero is shown to be fatally flawed because it requires dropping the
one-to-one correspondence between the symbols in the mathematical theory and
the different experimental configurations.Comment: Replaced Figs. 4,5 and caption of Fig.
Perturbation theory of transfer function matrices
Zeros of rational transfer function matrices are the eigenvalues
of associated polynomial system matrices , under minimality
conditions. In this paper we define a structured condition number for a simple
eigenvalue of a (locally) minimal polynomial system matrix
, which in turn is a simple zero of its transfer
function matrix . Since any rational matrix can be written as the
transfer function of a polynomial system matrix, our analysis yield a
structured perturbation theory for simple zeros of rational matrices
. To capture all the zeros of , regardless of whether
they are poles or not, we consider the notion of root vectors. As corollaries
of the main results, we pay particular attention to the special case of
being not a pole of since in this case the results get
simpler and can be useful in practice. We also compare our structured condition
number with Tisseur's unstructured condition number for eigenvalues of matrix
polynomials, and show that the latter can be unboundedly larger. Finally, we
corroborate our analysis by numerical experiments.Comment: 20 pages, 6 figure
Identifying the roles of university fundraisers in securing transformational gifts: Lessons from Canada
As university public funding diminishes so the need for private funding increases commensurately. We investigate how a purposive sample of 16 professional university fundraisers in Canada successfully secured large (>$5m CAD) transformation donations from high-net-worth Canadian philanthropists. Using an inductive process, we articulate three key roles (the 3Ns – Networker, Negotiator and Knowledge-broker) professional fundraisers use for securing transformational gifts. Collectively, these roles indicate the relational nature of transformational giving; gifts arise from a co-created dyadic process of fundraiser–philanthropist interaction. The recommendations have major implications for how university development teams are developed, structured, trained and rewarded. We suggest further research investigates how trust develops between fundraisers and transformational gift-givers, and the motivations for transformational giving
Anomalous radio emission from dust in the Helix
A byproduct of experiments designed to map the CMB is the recent detection of
a new component of foreground Galactic emission. The anomalous foreground at ~
10--30 GHz, unexplained by traditional emission mechanisms, correlates with
100um dust emission. We report that in the Helix the emission at 31 GHz and
100um are well correlated, and exhibit similar features on sky images, which
are absent in H\beta. Upper limits on the 250 GHz continuum emission in the
Helix rule out cold grains as candidates for the 31 GHz emission, and provide
spectroscopic evidence for an excess at 31 GHz over bremsstrahlung. We estimate
that the 100um-correlated radio emission, presumably due to dust, accounts for
at least 20% of the 31 GHz emission in the Helix. This result strengthens
previous tentative interpretations of diffuse ISM spectra involving a new dust
emission mechanism at radio frequencies. Very small grains have not been
detected in the Helix, which hampers interpreting the new component in terms of
spinning dust. The observed iron depletion in the Helix favors considering the
identity of this new component to be magnetic dipole emission from hot
ferromagnetic grains. The reduced level of free-free continuum we report also
implies an electronic temperature of Te=4600\pm1200K for the free-free emitting
material, which is significantly lower than the temperature of 9500\pm500K
inferred from collisionally-excited lines (abridged).Comment: Accepted for publication in Ap
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