3,429 research outputs found
Staircase Models from Affine Toda Field Theory
We propose a class of purely elastic scattering theories generalising the
staircase model of Al. B. Zamolodchikov, based on the affine Toda field
theories for simply-laced Lie algebras g=A,D,E at suitable complex values of
their coupling constants. Considering their Thermodynamic Bethe Ansatz
equations, we give analytic arguments in support of a conjectured
renormalisation group flow visiting the neighbourhood of each W_g minimal model
in turn.Comment: 22 pages, Saclay-Bologna preprint SPhT/92-065, DFUB-92-0
WORK TOGETHER… WHEN APART CHALLENGES AND WHAT IS NEED FOR EFFECTIVE VIRTUAL TEAMS
Increasingly competitive global markets and accelerating technological changes have increased the need for people to contact via electronic medium to have daily updates, the people those who could not able to meet face to face every day. Those who contact via electronic medium i.e. Virtual Team, are having number of benefit but to achieve these potential benefits, however, leaders need to overcome liabilities inherent in the lack of direct contact among team members and managers. Team members may not naturally know how to interact effectively across space and time. By this paper author try to throw some lights on the challenges that virtual team faces and try to elaborate what is needed for Virtual Team
Survival with Treated and Well-Controlled Blood Pressure: Findings from a Prospective Cohort Study.
AIM: To compare survival and incident cardiovascular disease between normotensive, untreated hypertensive, treated and poorly-controlled hypertensive and treated and well-controlled hypertensive adults.
METHODS AND RESULTS: Data from the British Regional Heart Study (men) and British Women's Heart and Health Study (women) were used (N = 6476). Blood pressure and treatment were assessed at baseline (1998-2001) when participants were aged 60-79 years and participants were followed up for a median of 8 years. Date and cause of death were obtained from death certificates and non-fatal cardiovascular disease events were obtained from repeat detailed medical record reviews. Of the whole cohort 52% of women and 49% of men had untreated hypertension and a further 22% and 18%, respectively, had poorly treated hypertension. Just 3% of women and 4% of men had treated and well controlled hypertension and 23% and 29%, respectively, were normotensive. Compared to normotensive individuals, incident cardiovascular disease (fatal and non-fatal) was increased in those with poorly-controlled hypertension (Hazard Ratio (HR): 1.88; 95%CI: 1.53, 2.30), those with untreated hypertension (HR 1.46; 95%CI 1.22, 1.75) and those who were well-controlled hypertension (HR 1.38; 95%CI 0.94, 2.03). Adjustment for baseline differences in mean blood pressure between the groups resulted in attenuation of the increased risk in the poorly-controlled (1.52 (1.18, 1.97) and untreated groups (1.21 (0.97, 1.52), but did not change the association in the well-controlled group. All-cause mortality was also increased in all three hypertension groups but estimates were imprecise with wide confidence intervals.
CONCLUSIONS: Half of women and men aged 60-79 in Britain had untreated hypertension and only a very small proportion of those with diagnosed and treated hypertension were well controlled. Those with hypertension, irrespective of whether this was treated and controlled or not, were at greater risk of future cardiovascular disease than those who are normotensive
Spin-to-Orbital Angular Momentum Conversion and Spin-Polarization Filtering in Electron Beams
We propose the design of a space-variant Wien filter for electron beams that
induces a spin half-turn and converts the corresponding spin angular momentum
variation into orbital angular momentum of the beam itself by exploiting a
geometrical phase arising in the spin manipulation. When applied to a spatially
coherent input spin-polarized electron beam, such a device can generate an
electron vortex beam, carrying orbital angular momentum. When applied to an
unpolarized input beam, the proposed device, in combination with a suitable
diffraction element, can act as a very effective spin-polarization filter. The
same approach can also be applied to neutron or atom beams.Comment: 9 pages, 5 figure
Polarization-controlled evolution of light transverse modes and associated Pancharatnam geometric phase in orbital angular momentum
We present an easy, efficient and fast method to generate arbitrary linear
combinations of light orbital angular momentum eigenstates
starting from a linearly polarized TEM laser beam. The method exploits
the spin-to-orbital angular momentum conversion capability of a
liquid-crystal-based -plate and a Dove prism inserted in a Sagnac polarizing
interferometer. The nominal generation efficiency is 100\%, being limited only
by reflection and scattering losses in the optical components. When closed
paths are followed on the polarization Poincar\'{e} sphere of the input beam,
the associated Pancharatnam geometric phase is transferred unchanged to the
orbital angular momentum state of the output beam.Comment: 5 pages and 5 figure
Optimisation of quantum Monte Carlo wave function: steepest descent method
We have employed the steepest descent method to optimise the variational
ground state quantum Monte Carlo wave function for He, Li, Be, B and C atoms.
We have used both the direct energy minimisation and the variance minimisation
approaches. Our calculations show that in spite of receiving insufficient
attention, the steepest descent method can successfully minimise the wave
function. All the derivatives of the trial wave function respect to spatial
coordinates and variational parameters have been computed analytically. Our
ground state energies are in a very good agreement with those obtained with
diffusion quantum Monte Carlo method (DMC) and the exact results.Comment: 13 pages, 3 eps figure
Femtosecond-laser pumped CdSiP<sub>2</sub> optical parametric oscillator producing 100 MHz pulses centered at 6.2 μm
Resolution in Linguistic Propositional Logic based on Linear Symmetrical Hedge Algebra
The paper introduces a propositional linguistic logic that serves as the
basis for automated uncertain reasoning with linguistic information. First, we
build a linguistic logic system with truth value domain based on a linear
symmetrical hedge algebra. Then, we consider G\"{o}del's t-norm and t-conorm to
define the logical connectives for our logic. Next, we present a resolution
inference rule, in which two clauses having contradictory linguistic truth
values can be resolved. We also give the concept of reliability in order to
capture the approximative nature of the resolution inference rule. Finally, we
propose a resolution procedure with the maximal reliability.Comment: KSE 2013 conferenc
Generation of Nondiffracting Electron Bessel Beams
Almost 30 years ago, Durnin discovered that an optical beam with a transverse intensity profile in the form of a Bessel function of the first order is immune to the effects of diffraction. Unlike most laser beams, which spread upon propagation, the transverse distribution of these Bessel beams remains constant. Electrons also obey a wave equation (the Schrödinger equation), and therefore Bessel beams also exist for electron waves. We generate an electron Bessel beam by diffracting electrons from a nanoscale phase hologram. The hologram imposes a conical phase structure on the electron wave-packet spectrum, thus transforming it into a conical superposition of infinite plane waves, that is, a Bessel beam. We verify experimentally that these beams can propagate for 0.6 m without measurable spreading and can also reconstruct their intensity distributions after being partially obstructed by an obstacle. Finally, we show by numerical calculations that the performance of an electron microscope can be increased dramatically through use of these beams
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