634 research outputs found
Solid-state time-to-pulse-height converter developed
Solid-state circuit produces an output pulse with an amplitude directly proportional to the time interval between two input pulses. It uses selected circuit options to achieve variable mode operation and a tunnel diode controls the charging time of a capacitor in proportion to the time interval being measured
Identification of key water quality characteristics affecting the filterability of biologically treated effluent in low-pressure membrane filtration
There are many water quality characteristics which could influence the filterability of biologically treated effluent from Melbourne's Western Treatment Plant (WTP). Statistical correlation was used to identify the key water characteristics affecting the microfiltration (MF) and ultrafiltration (UF) filterability in terms of permeate volume of the treated effluent. The models developed showed that turbidity, dissolved organic carbon (DOC) and total suspended solids (TSS) were the key factors which influenced the MF and UF filterability. Turbidity was the dominant factor affecting the accuracy of the model for MF filterability while DOC was the major factor affecting the accuracy of the model for UF filterability. A prediction accuracy of 85% was obtained for MF and 86% for UF filterability of the WTP effluent. The characteristics of the organic components of the wastewater were demonstrated by EEM spectra to have seasonal variation which would have reduced the prediction accuracy. As turbidity, DOC and TSS can be determined on-line, the models would be useful for rapid prediction of the filterability of WTP effluent and this may assist the control of low-pressure membrane filtration processes
Investigating tiredness in Australian general practice - Do pathology tests help in diagnosis?
Copyright © 2003 Australian College of General Practitioners Copyright to Australian Family Physician. Reproduced with permission. Permission to reproduce must be sought from the publisher, The Royal Australian College of General Practitioners.INTRODUCTION: Tiredness is a common presentation in general practice for which pathology tests are commonly ordered. Our aim was to study their utilisation for tiredness. METHODS: We examined an integrated database which contains the medical records for 58,139 patients and their 696,518 associated general practitioner encounters. Three hundred and forty-two patients and their 1652 associated encounters were randomly selected out of 12,291 patients and their 26,748 associated encounters that had mentioned tiredness (or a synonym). RESULTS: One hundred and eighty-one patients (53%) had at least one pathology test ordered at any time in their episode of care. Patients over 60 years of age, patients who consulted their GP more than once and patients without comorbidity were more likely to have a pathology test ordered. Only 12 patients (3%) had a significant clinical diagnosis based on an abnormal pathology test. CONCLUSION: Pathology testing for patients presenting with tiredness is high. Most tests do not yield a significant clinical diagnosis.A Gialamas, JJ Beilby, NL Pratt, R Henning, JE Marley and JF Roddic
Functional Brain Imaging with Multi-Objective Multi-Modal Evolutionary Optimization
Functional brain imaging is a source of spatio-temporal data mining problems.
A new framework hybridizing multi-objective and multi-modal optimization is
proposed to formalize these data mining problems, and addressed through
Evolutionary Computation (EC). The merits of EC for spatio-temporal data mining
are demonstrated as the approach facilitates the modelling of the experts'
requirements, and flexibly accommodates their changing goals
Phase fluctuations in superconductors: from Galilean invariant to quantum XY models
We analyze the corrections to the superfluid density due to phase
fluctuations within both a continuum and a lattice model for - and d-wave
superconductors. We expand the phase-only action beyond the Gaussian level and
compare our results with the quantum XY model both in the quantum and in the
classical regime. We find new dynamic anharmonic vertices, absent in the
quantum XY model, which are responsible for the vanishing of the correction to
the superfluid density at zero temperature in a continuum (Galilean invariant)
model. Moreover the phase-fluctuation effects are reduced with respect to the
XY model by a factor at least of order .Comment: 4 pages; shorter version, accepted for publication on Phys. Rev. B
Rapid Com
Anisotropy in the helicity modulus of a 3D XY-model: application to YBCO
We present a Monte Carlo study of the helicity moduli of an anisotropic
classical three-dimensional (3D) XY-model of YBCO in superconducting state. It
is found that both the ab-plane and the c-axis helicity moduli, which are
proportional to the inverse square of the corresponding magnetic field
penetration depth, vary linearly with temperature at low temperatures. The
result for the c-axis helicity modulus is in disagreement with the experiments
on high quality samples of YBCO. Thus we conclude that purely classical phase
fluctuations of the superconducting order parameter cannot account for the
observed c-axis electrodynamics of YBCO.Comment: 7 pages, 1 figur
Strong-coupling perturbation theory for the two-dimensional Bose-Hubbard model in a magnetic field
The Bose-Hubbard model in an external magnetic field is investigated with
strong-coupling perturbation theory. The lowest-order secular equation leads to
the problem of a charged particle moving on a lattice in the presence of a
magnetic field, which was first treated by Hofstadter. We present phase
diagrams for the two-dimensional square and triangular lattices, showing a
change in shape of the phase lobes away from the well-known power-law behavior
in zero magnetic field. Some qualitative agreement with experimental work on
Josephson-junction arrays is found for the insulating phase behavior at small
fields.Comment: 7 pages, 5 figures include
Anisotropy in the helicity modulus of a quantum 3D XY-model: application to YBCO
We present a variational study of the helicity moduli of an anisotropic
quantum three-dimensional (3D) XY-model of YBCO in superconducting state. It is
found that both the ab-plane and the c-axis helicity moduli, which are
proportional to the inverse square of the corresponding magnetic field
penetration depth, vary with temperature T as T to the fourth power in the zero
temperature limit. Moreover, the c-axis helicity modulus drops with temperature
much faster than the ab-plane helicity modulus because of the weaker Josephson
couplings along the c-axis compared to those along the ab-plane. These findings
are in disagreement with the experiments on high quality samples of YBCO.Comment: 9 pages, 1 figur
The Bose Metal: gauge field fluctuations and scaling for field tuned quantum phase transitions
In this paper, we extend our previous discussion of the Bose metal to the
field tuned case. We point out that the recent observation of the metallic
state as an intermediate phase between the superconductor and the insulator in
the field tuned experiments on MoGe films is in perfect consistency with the
Bose metal scenario. We establish a connection between general dissipation
models and gauge field fluctuations and apply this to a discussion of scaling
across the quantum phase boundaries of the Bose metallic state. Interestingly,
we find that the Bose metal scenario implies a possible {\em two} parameter
scaling for resistivity across the Bose metal-insulator transition, which is
remarkably consistent with the MoGe data. Scaling at the superconductor-metal
transition is also proposed, and a phenomenolgical model for the metallic state
is discussed. The effective action of the Bose metal state is described and its
low energy excitation spectrum is found to be .Comment: 15 pages, 1 figur
One-dimensional Josephson arrays as superlattices for single Cooper pairs
We investigate uniform one-dimensional arrays of small Josephson junctions
(, ) with a realistic Coulomb interaction (here is the screening length
in units of the lattice constant of the array). At low energies this system can
be described in terms of interacting Bose particles (extra single Cooper pairs)
on the lattice. With increasing concentration of extra Cooper pairs, a
crossover from the Bose gas phase to the Wigner crystal phase and then to the
superlattice regime occurs. The phase diagram in the superlattice regime
consists of commensurable insulating phases with ( is integer)
separated by superconducting regions where the current is carried by
excitations with {\em fractional} electric charge . The Josephson
current through a ring-shaped array pierced by magnetic flux is calculated for
all of the phases.Comment: 4 pages (LATEX), 2 figure
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