31,278 research outputs found

### Changing times of feminism and higher education: From community to employability

This article discusses the creation of space and time for feminist approaches in higher education in the context of shifting community and employment relations and the restructuring of higher education space-time. It draws on the reflections of three feminist academics concerning aspects of their work biographies in two very different higher education settings. It explores the shift from working in an academic department concerned with community studies to one concerned with education and related employment. The article focuses on the attempt to sustain feminist practices through these changing times and settings and is informed by the work on time and space by Barbara Adam, Henri Lefebvre and Doreen Massey. Â© 2011 Taylor & Francis

### Green's function theory of quasi-two-dimensional spin-half Heisenberg ferromagnets: stacked square versus stacked kagom\'e lattice

We consider the thermodynamic properties of the quasi-two-dimensional
spin-half Heisenberg ferromagnet on the stacked square and the stacked kagom\'e
lattices by using the spin-rotation-invariant Green's function method. We
calculate the critical temperature $T_C$, the uniform static susceptibility
$\chi$, the correlation lengths $\xi_\nu$ and the magnetization $M$ and
investigate the short-range order above $T_C$. We find that $T_C$ and $M$ at
$T>0$ are smaller for the stacked kagom\'e lattice which we attribute to
frustration effects becoming relevant at finite temperatures.Comment: shortened version as published in PR

### Low pressure arc electrode

Reducing the pressure in the vicinity of the arc attachment point by allowing the gas to flow through a supersonic nozzle minimizes local heating rates, prevents ablation, and increases the efficiency of coaxial gas-flow arcs

### Quantum $J_1$--$J_2$ antiferromagnet on the stacked square lattice: Influence of the interlayer coupling on the ground-state magnetic ordering

Using the coupled-cluster method (CCM) and the rotation-invariant Green's
function method (RGM), we study the influence of the interlayer coupling
$J_\perp$ on the magnetic ordering in the ground state of the spin-1/2
$J_1$-$J_2$ frustrated Heisenberg antiferromagnet ($J_1$-$J_2$ model) on the
stacked square lattice. In agreement with known results for the $J_1$-$J_2$
model on the strictly two-dimensional square lattice ($J_\perp=0$) we find that
the phases with magnetic long-range order at small $J_2< J_{c_1}$ and large
$J_2> J_{c_2}$ are separated by a magnetically disordered (quantum
paramagnetic) ground-state phase. Increasing the interlayer coupling
$J_\perp>0$ the parameter region of this phase decreases, and, finally, the
quantum paramagnetic phase disappears for quite small $J_\perp \sim 0.2 ... 0.3
J_1$.Comment: 4 pages, 3 figure

### A remark on the multipliers on spaces of weak products of functions

If $\mathcal{H}$ denotes a Hilbert space of analytic functions on a region
$\Omega \subseteq \mathbb{C}^d$, then the weak product is defined by
$\mathcal{H}\odot\mathcal{H}=\left\{h=\sum_{n=1}^\infty f_n g_n :
\sum_{n=1}^\infty \|f_n\|_{\mathcal{H}}\|g_n\|_{\mathcal{H}} <\infty\right\}.$
We prove that if $\mathcal{H}$ is a first order holomorphic Besov Hilbert space
on the unit ball of $\mathbb{C}^d$, then the multiplier algebras of
$\mathcal{H}$ and of $\mathcal{H}\odot\mathcal{H}$ coincide.Comment: v1: 6 pages. To appear Concr. Ope

### On undecidability results of real programming languages

Original article can be found at : http://www.vmars.tuwien.ac.at/ Copyright Institut fur Technische InformatikOften, it is argued that some problems in data-flow analysis such as e.g. worst case execution time analysis are undecidable (because the halting problem is) and therefore only a conservative approximation of the desired information is possible. In this paper, we show that the semantics for some important real programming languages â€“ in particular those used for programming embedded devices â€“ can be modeled as finite state systems or pushdown machines. This implies that the halting problem becomes decidable and therefore invalidates popular arguments for using conservative analysis

### The frustrated spin-1/2 J1-J2 Heisenberg ferromagnet on the square lattice: Exact diagonalization and Coupled-Cluster study

We investigate the ground-state magnetic order of the spin-1/2 J1-J2
Heisenberg model on the square lattice with ferromagnetic nearest-neighbor
exchange J1<0 and frustrating antiferromagnetic next-nearest neighbor exchange
J2>0. We use the coupled-cluster method to high orders of approximation and
Lanczos exact diagonalization of finite lattices of up to N=40 sites in order
to calculate the ground-state energy, the spin-spin correlation functions, and
the magnetic order parameter. We find that the transition point at which the
ferromagnetic ground state disappears is given by J2^{c1}=0.393|J1| (exact
diagonalization) and J2^{c1}=0.394|J1| (coupled-cluster method). We compare our
results for ferromagnetic J1 with established results for the spin-1/2 J1-J2
Heisenberg model with antiferromagnetic J1. We find that both models (i.e.,
ferro- and antiferromagnetic J1) behave similarly for large J2, although
significant differences between them are observed for J2/|J1| \lesssim 0.6.
Although the semiclassical collinear magnetic long-range order breaks down at
J2^{c2} \approx 0.6J1 for antiferromagnetic J1, we do not find a similar
breakdown of this kind of long-range order until J2 \sim 0.4|J1| for the model
with ferromagnetic J1. Unlike the case for antiferromagnetic J1, if an
intermediate disordered phase does occur between the phases exhibiting
semiclassical collinear stripe order and ferromagnetic order for ferromagnetic
J1 then it is likely to be over a very small range below J2 \sim 0.4|J1|.Comment: 15 pages, 7 figures, 2 table

### Three- and Four-point correlators of excited bosonic twist fields

We compute three- and four-point correlation functions containing excited
bosonic twist fields. Our results can be used to determine properties, such as
lifetimes and production rates, of massive string excitations localised at
D-brane intersections, which could be signatures of a low string scale even if
the usual string resonances are inaccessible to the LHC.Comment: 42 pages, no figure

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