1,372 research outputs found
Towards the parameterisation of the Hubbard model for salts of BEDT-TTF: A density functional study of isolated molecules
We calculate the effective Coulomb repulsion between electrons/holes, U, and
site energy for an isolated BEDT-TTF [bis(ethylenedithio)tetrathiafulvalene]
molecule in vacuo. U=4.2 \pm 0.1 eV for 44 experimental geometries taken from a
broad range of conformations, polymorphs, anions, temperatures, and pressures
(the quoted `error' is one standard deviation). Hence we conclude that U is
essentially the same for all of the compounds studied. This shows that the
strong (hydrostatic and chemical) pressure dependence observed in the phase
diagrams of the BEDT-TTF salts is not due to U. Therefore, if the Hubbard model
is sufficient to describe the phase diagram of the BEDT-TTF salts there must be
significant pressure dependence on the intramolecular terms in the Hamiltonian
and/or the reduction of the Hubbard U due to the interaction of the molecule
with the polarisable crystal environment. The renormalised value of U is
significantly smaller than the bare value of the Coulomb integral:
F_0=5.2\pm0.1 eV across the same set of geometries, emphasising the importance
of using the renormalised value of U. The site energy (for holes), xi=5.0\pm0.2
eV, varies only a little more than U across the same set of geometries.
However, we argue that this plays a key role in understanding the role of
disorder in ET salts in general and in explaining the difference between the
beta_L and beta_H phases of beta-(BEDT-TTF)_2I_3 in particular.Comment: 13 pages, 6 figures, also see animations at
http://www.youtube.com/watch?v=3K2kP8hWpZI,
http://www.youtube.com/watch?v=wIz1cRsSdEs and
http://www.youtube.com/watch?v=bNzUBAS6AFM, Expanded discussion of
renormalisation effects. To appear in J. Chem. Phy
Date-setting in America for the Second Coming of Christ During the Late Nineteenth and Early Twentieth Century
The time of Second Advent of Jesus Christ has been of interest to His followers throughout the Christian age, and from time to time, some have gone so far as to fix a date for the event. In doing so, they have looked to Bible prophecies for a clue to the time of Christ\u27s return. Perhaps the outstanding period of date-setting was during the late eighteenth and early nineteenth centuries. During that time, there was a general advent awakening throughout the world. This was very marked in America where we find prophecy used during the revivals of the 1840\u27s in an effort to determine the exact date. The fact that He did not come at the time appointed has caused the Christian world to look with disdain upon those who tried in recent years, to determine the date of Christ\u27s return.
The purpose of this study has been to investigate the setting of dates, in America, for the second coming of Christ during the late nineteenth and early twentieth century, endeavoring to ascertain what prophecies were used in determining the date, and how these prophecies were interpreted
Radio-frequency reflectometry on an undoped AlGaAs/GaAs single electron transistor
Radio frequency reflectometry is demonstrated in a sub-micron undoped
AlGaAs/GaAs device. Undoped single electron transistors (SETs) are attractive
candidates to study single electron phenomena due to their charge stability and
robust electronic properties after thermal cycling. However these devices
require a large top-gate which is unsuitable for the fast and sensitive radio
frequency reflectometry technique. Here we demonstrate rf reflectometry is
possible in an undoped SET.Comment: Four pages, three figures, one supplementary fil
The effect of caffeine mouth rinse on self-paced cycling performance
The aim of the study was to determine whether caffeine mouth rinse would improve 30 min self-paced cycling trial. Twelve healthy active males (age 20.5±0.7 years, mass 87.4±18.3 kg) volunteered for the study. They attended the laboratory on 3 separate occasions performing a 30 min self-paced cycling trial. On one occasion water was given as a mouth rinse for 5 s (PLA), on another occasion a 6.4% maltodextrin (CHO) solution was given for 5 s and finally a caffeine solution (containing 32 mg of caffeine dissolved in 125 ml water; CAF) was given for 5 s. Distance cycled, heart rate, ratings of perceived exertion, cadence, speed and power output were recorded throughout all trials. Distance cycled during the CAF mouth rinse trial (16.2±2.8 km) was significantly greater compared to PLA trial (14.9±2.6 km). There was no difference between CHO and CAF trials (P=0.89). Cadence, power and velocity were significantly greater during the CAF trial compared to both PLA and CHO (P0.05). Caffeine mouth rinse improves 30 min cycling performance by allowing the participant to increase cadence, power and velocity without a concurrent increase in perceived exertion and heart rate
An Evaluation of the Marine Zoning and Aquaculture Plans in the Great Sandy Region, Australia: Indicators for Successful Integrated Coastal Zone Management
Plasma Cholesterol Ester Fatty Acids: A New Biochemical Abnormality in Obstructive Jaundice
Changes in fatty acid patterns may explain many of the observed abnormalities found in
obstructive jaundice. This study looked at fatty acids in plasma cholesterol esters, in a group of
patients with obstructive jaundice and a matched group of controls. Significant abnormalities
were demonstrated, most importantly a fall in essential fatty acids, in the jaundiced group.
Overall the saturation of this fraction, as assessed by double bond index, rose. The essential fatty
acids are important as factors in membrane function and as precursors of eicosanoids. The
abnormalities found in this study provide further evidence of the significance of EFA in patients
with obstructive jaundice
On CARICOM and the Varying Levels of and Motives for Integration Among the Member States
In an era of rapid transport and communication, spectators have come to expect a bridging of the classic political, social, and economic divide between states. It is taken for granted that states have more to work together than to strive independently for. CARICOM is the Caribbean\u27s experiment at regional integration and it member states have pledged their ostensible support. This study is aimed at gauging the true levels of enthusiasm of the member states, which have varied among them and over time. By analysing the trade pattern of the Members with each other in comparison with the rest of the world, the commitment of the member states was ascertained. The study explores various issues and characteristics of the region that help to bolster or threaten increased cooperation among the Members. Among these, external dependency, social peculiarities, and the vulnerability of the Members makes for an interesting and uncertain prediction for the group\u27s future. Using various indicators and indices from such sources as the World Bank, International Monetary Fund, and the Commonwealth Secretariat the states were compared and their various situations analysed to give reason for their varied levels of commitment to regionalisation through CARICOM. Certainly possessing more in common than not, the Members prove an exception, or perhaps a refutation to the idea of international cooperation being positively affected or catalysed by commonality
From coinductive proofs to exact real arithmetic: theory and applications
Based on a new coinductive characterization of continuous functions we
extract certified programs for exact real number computation from constructive
proofs. The extracted programs construct and combine exact real number
algorithms with respect to the binary signed digit representation of real
numbers. The data type corresponding to the coinductive definition of
continuous functions consists of finitely branching non-wellfounded trees
describing when the algorithm writes and reads digits. We discuss several
examples including the extraction of programs for polynomials up to degree two
and the definite integral of continuous maps
Malignant Pancreatic Polypeptide Secreting Tumour of Islet Cells: A Case for Aggressive Surgical Palliation
A case of a malignant pancreatic polypeptide secreting tumour is reported. The tumour was metastatic
at presentation at which time it was excised. Pancreatic duct obstruction occurred 3 years after excision causing severe pain on eating. Major palliative surgery, in the form of a pancreatico-jejunostomy, cured the severe symptoms. The patient survives, largely symptom free, over six years after original excision. This case illustrates the need for aggressive management of symptoms in tumours in which long term survival is possible despite locally advanced or metastatic disease
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