7,531 research outputs found
Leading change in higher education
This article considers the situation in the UK higher education system and investigates specifically the leadership practice in a cluster of UK institutions as they changed their status. The research goes further to advocate a form of contextualized leadership that is relevant to higher institutions under change
Resource recovery and remediation of highly alkaline residues : a political-industrial ecology approach to building a circular economy
Highly alkaline industrial residues (e.g., steel slag, bauxite processing residue (red mud) and ash from coal combustion) have been identified as stocks of potentially valuable metals. Technological change has created demand for metals, such as vanadium and certain rare earth elements, in electronics associated with renewable energy generation and storage. Current raw material and circular economy policy initiatives in the EU and industrial ecology research all promote resource recovery from residues, with research so far primarily from an environmental science perspective. This paper begins to address the deficit of research into the governance of resource recovery from a novel situation where re-use involves extraction of a component from a bulk residue that itself represents a risk to the environment. Taking a political industrial ecology approach, we briefly present emerging techniques for recovery and consider their regulatory implications in the light of potential environmental impacts. The paper draws on EU and UK regulatory framework for these residues along with semi-structured interviews with industry and regulatory bodies. A complex picture emerges of entwined ownerships and responsibilities for residues, with past practice and policy having a lasting impact on current possibilities for resource recovery
Conceptual aspects of line tensions
We analyze two representative systems containing a three-phase-contact line:
a liquid lens at a fluid--fluid interface and a liquid drop in contact with a
gas phase residing on a solid substrate. We discuss to which extent the
decomposition of the grand canonical free energy of such systems into volume,
surface, and line contributions is unique in spite of the freedom one has in
positioning the Gibbs dividing interfaces. In the case of a lens it is found
that the line tension is independent of arbitrary choices of the Gibbs dividing
interfaces. In the case of a drop, however, one arrives at two different
possible definitions of the line tension. One of them corresponds seamlessly to
that applicable to the lens. The line tension defined this way turns out to be
independent of choices of the Gibbs dividing interfaces. In the case of the
second definition,however, the line tension does depend on the choice of the
Gibbs dividing interfaces. We provide equations for the equilibrium contact
angles which are form-invariant with respect to notional shifts of dividing
interfaces which only change the description of the system. Conceptual
consistency requires to introduce additional stiffness constants attributed to
the line. We show how these constants transform as a function of the relative
displacements of the dividing interfaces. The dependences of the contact angles
on lens or drop volumes do not render the line tension alone but a combination
of the line tension, the Tolman length, and the stiffness constants of the
line.Comment: 34 pages, 9 figure
Grand potential in thermodynamics of solid bodies and surfaces
Using the chemical potential of a solid in a dissolved state or the
corresponding component of the chemical potential tensor at equilibrium with
the solution, a new concept of grand thermodynamic potential for solids has
been suggested. This allows generalizing the definition of Gibbs' quantity
(surface work often called the solid-fluid interfacial free energy) at
a planar surface as an excess grand thermodynamic potential per unit surface
area that (1) does not depend on the dividing surface location and (2) is
common for fluids and solids.Comment: 6 page
Topics in Cubic Special Geometry
We reconsider the sub-leading quantum perturbative corrections to N=2 cubic
special Kaehler geometries. Imposing the invariance under axion-shifts, all
such corrections (but the imaginary constant one) can be introduced or removed
through suitable, lower unitriangular symplectic transformations, dubbed
Peccei-Quinn (PQ) transformations. Since PQ transformations do not belong to
the d=4 U-duality group G4, in symmetric cases they generally have a
non-trivial action on the unique quartic invariant polynomial I4 of the charge
representation R of G4. This leads to interesting phenomena in relation to
theory of extremal black hole attractors; namely, the possibility to make
transitions between different charge orbits of R, with corresponding change of
the supersymmetry properties of the supported attractor solutions. Furthermore,
a suitable action of PQ transformations can also set I4 to zero, or vice versa
it can generate a non-vanishing I4: this corresponds to transitions between
"large" and "small" charge orbits, which we classify in some detail within the
"special coordinates" symplectic frame. Finally, after a brief account of the
action of PQ transformations on the recently established correspondence between
Cayley's hyperdeterminant and elliptic curves, we derive an equivalent,
alternative expression of I4, with relevant application to black hole entropy.Comment: 1+39 page
Quantum bistability and spin current shot noise of a single quantum dot coupled to an optical microcavity
Here we explore spin dependent quantum transport through a single quantum dot
coupled to an optical microcavity. The spin current is generated by electron
tunneling between a single doped reservoir and the dot combined with intradot
spin flip transitions induced by a quantized cavity mode. In the limit of
strong Coulomb blockade, this model is analogous to the Jaynes-Cummings model
in quantum optics and generates a pure spin current in the absence of any
charge current. Earlier research has shown that in the classical limit where a
large number of such dots interact with the cavity field, the spin current
exhibits bistability as a function of the laser amplitude that drives the
cavity. We show that in the limit of a single quantum dot this bistability
continues to be present in the intracavity photon statistics. Signatures of the
bistable photon statistics manifest themselves in the frequency dependent shot
noise of the spin current despite the fact that the quantum mechanical average
spin current no longer exhibits bistability. Besides having significance for
future quantum dot based optoelectronic devices, our results shed light on the
relation between bistability, which is traditionally viewed as a classical
effect, and quantum mechanics
Thermal analysis applied to estimation of solidification kinetics of Al–Si aluminium alloys
Evaluation of solidification kinetics by thermal analysis is a useful tool for quality control of Al–Si melts before pouring provided it is rapid and highly reproducible. Series of thermal analysis records made with standard cups are presented that show good reproducibility. They are evaluated using a Newton’s like approach to get the instantaneous heat evolution and from it solidification kinetics. An alternative way of calculating the zero line is proposed which is validated by the fact that the latent heat of solidification thus evaluated is within 5% of the value calculated from thermodynamic data. Solidification kinetics was found highly reproducible provided appropriate experimental conditions were achieved: high enough casting temperature for the cup to heat up to the metal temperature well before solidification starts; and equal and homogeneous temperatures of the metal and of the cup at any time in the temperature range used for integration
Light-Induced Atomic Desorption for loading a Sodium Magneto-Optical Trap
We report studies of photon-stimulated desorption (PSD), also known as
light-induced atomic desorption(LIAD), of sodium atoms from a vacuum cell glass
surface used for loading a magneto-optical trap (MOT). Fluorescence detection
was used to record the trapped atom number and the desorption rate. We observed
a steep wavelength dependence of the desorption process above 2.6 eV photon
energy, a result significant for estimations of sodium vapor density in the
lunar atmosphere. Our data fit well to a simple model for the loading of the
MOT dependent only on the sodium desorption rate and residual gas density. Up
to 3.7x10^7 Na atoms were confined under ultra-high vacuum conditions, creating
promising loading conditions for a vapor cell based atomic Bose-Einstein
condensate of sodium.Comment: Sodium LIAD loaded MOT, 7 pages, 5 figures. Revised submitted
manuscript with minor corrections, new data presented, Fig.5 change
Mesoscopic Phase Fluctuations: General Phenomenon in Condensed Matter
General conditions for the occurrence of mesoscopic phase fluctuations in
condensed matter are considered. The description of different thermodynamic
phases, which coexist as a mixture of mesoscopically separated regions, is
based on the {\it theory of heterophase fluctuations}. The spaces of states,
typical of the related phases, are characterized by {\it weighted Hilbert
spaces}. Several models illustrate the main features of heterophase condensed
matter.Comment: 23 pages, Latex, no figure
A recommended method for detecting salmonellae in composted biosolids
It has been found in Australia and in the United States that composting does not always result in the complete removal of salmonellae from biosolids. It is therefore likely that monitoring of composted Biosolids for salmonellae will be required in Australia to ensure the safety of biosolids products. At present rapid methods of detection such as PCR and ELISA are not sufficiently developed to monitor environmental samples. The relative efficiency of various culture methods for detecting salmonellae in composted biosolids was therefore investigated. On the basis of the results a presence/absence method is recommended for the detection of salmonellae in biosolids products. The recommended technique involves pre-enrichment of samples, followed by enrichment in Rappaport-Vassiliadis and mannitol selenite enrichment broths, and isolation on lysine mannitol glycerol agar
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