SiGe p-channel MOSFETs with tungsten gate

A self-aligned SiGe p-channel MOSFET tungsten gate process with 0.1 μm resolution is demonstrated. Interface charge densities of MOS capacitors realised with the low pressure sputtered tungsten process are comparable with thermally evaporated aluminium gate technologies (5×1010cm-2 and 2×1011 cm -2 for W and Al, respectively). Initial results from 1 μm gate length SiGe p-channel MOSFETs using the tungsten-based process show devices with a transconductance of 33 mS/mm and effective channel mobility of 190 cm

Classical and quantum pumping in closed systems

Pumping of charge (Q) in a closed ring geometry is not quantized even in the strict adiabatic limit. The deviation form exact quantization can be related to the Thouless conductance. We use Kubo formalism as a starting point for the calculation of both the dissipative and the adiabatic contributions to Q. As an application we bring examples for classical dissipative pumping, classical adiabatic pumping, and in particular we make an explicit calculation for quantum pumping in case of the simplest pumping device, which is a 3 site lattice model.Comment: 5 pages, 3 figures. The long published version is cond-mat/0307619. This is the short unpublished versio

Thermodynamics of Random Ferromagnetic Antiferromagnetic Spin-1/2 Chains

Using the quantum Monte Carlo Loop algorithm, we calculate the temperature dependence of the uniform susceptibility, the specific heat, the correlation length, the generalized staggered susceptibility and magnetization of a spin-1/2 chain with random antiferromagnetic and ferromagnetic couplings, down to very low temperatures. Our data show a consistent scaling behavior in all the quantities and support strongly the conjecture drawn from the approximate real-space renormalization group treatment.A statistical analysis scheme is developed which will be useful for the search of scaling behavior in numerical and experimental data of random spin chains.Comment: 13 pages, 13 figures, RevTe

Probing the energy bands of a Bose-Einstein condensate in an optical lattice

We simulate three experimental methods which could be realized in the laboratory to probe the band excitation energies and the momentum distribution of a Bose-Einstein condensate inside an optical lattice. The values of the excitation energies obtained in these different methods agree within the accuracy of the simulation. The meaning of the results in terms of density and phase deformations is tested by studying the relaxation of a phase-modulated condensate towards the ground state.Comment: 5 pages, 5 figure

Fracture in the Elderly Multidisciplinary Rehabilitation (FEMuR):study protocol for a phase II randomised feasibility study of a multidisciplinary rehabilitation package following hip fracture [ ISRCTN22464643 ]

Background Proximal femoral fracture is a common, major health problem in old age resulting in loss of functional independence and a high-cost burden on society, with estimated health and social care costs of £2.3 billion per year in the UK. Rehabilitation has the potential to maximise functional recovery and maintain independent living, but evidence of effectiveness is lacking. Usual rehabilitation care is delivered by a multi-disciplinary team in the hospital and in the community. An ‘enhanced rehabilitation’ intervention has been developed consisting of a workbook, goal-setting diary and extra therapy sessions, designed to improve self-efficacy and increase the amount and quality of the practice of physical exercise and activities of daily living. Methods/design This paper describes the design of a phase II study comprising an anonymous cohort of all proximal femoral fracture patients admitted to the three acute hospitals in Betsi Cadwaladr University Health Board over a 6-month period with a randomised feasibility study comparing the enhanced rehabilitation intervention with usual care. These will assess the feasibility of a future definitive randomised controlled trial and concurrent economic evaluation in terms of recruitment, retention, outcome measure completion, compliance with the intervention and fidelity of delivery, health service use data, willingness to be randomised and effect size for a future sample size calculation. Focus groups will provide qualitative data to contribute to the assessment of the acceptability of the intervention amongst patients, carers and rehabilitation professionals and the feasibility of delivering the planned intervention. The primary outcome measure is function assessed by the Barthel Index. Secondary outcomes measure the ability to perform activities of daily living, anxiety and depression, potential mediators of outcomes such as hip pain, self-efficacy and fear of falling, health utility, health service use, objectively assessed physical function and adverse events. Participants’ preference for rehabilitation services will be assessed in a discrete choice experiment. Discussion Phase II studies are an opportunity to not only assess the feasibility of trial methods but also to compare different methods of outcome measurement and novel methods of obtaining health service use data from routinely collected patient information. Trial registration Current Controlled Trials ISRCTN22464643, UKCRN16677

Random Exchange Quantum Heisenberg Chains

The one-dimensional quantum Heisenberg model with random $\pm J$ bonds is studied for $S=\frac{1}{2}$ and $S=1$. The specific heat and the zero-field susceptibility are calculated by using high-temperature series expansions and quantum transfer matrix method. The susceptibility shows a Curie-like temperature dependence at low temperatures as well as at high temperatures. The numerical results for the specific heat suggest that there are anomalously many low-lying excitations. The qualitative nature of these excitations is discussed based on the exact diagonalization of finite size systems.Comment: 13 pages, RevTex, 12 figures available on request ([email protected]

Two-sided Grassmann-Rayleigh quotient iteration

The two-sided Rayleigh quotient iteration proposed by Ostrowski computes a pair of corresponding left-right eigenvectors of a matrix $C$. We propose a Grassmannian version of this iteration, i.e., its iterates are pairs of $p$-dimensional subspaces instead of one-dimensional subspaces in the classical case. The new iteration generically converges locally cubically to the pairs of left-right $p$-dimensional invariant subspaces of $C$. Moreover, Grassmannian versions of the Rayleigh quotient iteration are given for the generalized Hermitian eigenproblem, the Hamiltonian eigenproblem and the skew-Hamiltonian eigenproblem.Comment: The text is identical to a manuscript that was submitted for publication on 19 April 200