590 research outputs found
Model for the low-temperature magnetic phases observed in doped YBa_2Cu_3O_{6+x}
A classical statistical model for the antiferromagnetic (AFM) ordering of the
Cu-spins in the CuO_2 planes of reduced YBa_2Cu_3O_{6+x} type materials is
presented. The magnetic phases considered are the experimentally observed
high-temperature AFI phase with ordering vector Q_I=(1/2,1/2,0), and the
low-temperature phases: AFII with Q_II=(1/2,1/2,1/2) and intermediate TA (Turn
Angle) phases TAI, TAII and TAIII with components of both ordering vectors. It
is shown that the AFII and TA phases result from an effective ferromagnetic
(FM) type coupling mediated by free spins in the CuO_x basal plane. Good
agreement with experimental data is obtained for realistic model parameters.Comment: 11 pages, 2 Postscript figures, Submitted to Phys.Rev.Let
Theory of Electromagnetic Wave Transmission through Metallic Gratings of Subwavelength Slits
We present FDTD calculations for transmission of light and other
electromagnetic waves through periodic arrays of slits in a metallic slab. The
results show resonant, frequency dependent, transmittance peaks for
subwavelength widths of the slits which can be up to a factor of ten with
respect to those out of resonance. Although our conclusions agree with previous
work by Lezec and Thio as regards both the magnitude of the enhancement and the
lack of contribution of surface plasmon polaritons of the metal surface to this
effect, we derive an interpretation from a theory that deals with emerging
beam- Rayleigh anomalies of the grating, and with Fabry-Perot resonances of the
perforated slab considered as an effective medium.Comment: 12 pages 3 figure
Theoretical study of the absorption spectra of the lithium dimer
For the lithium dimer we calculate cross sections for absorption of radiation
from the vibrational-rotational levels of the ground X [singlet Sigma g +]
electronic state to the vibrational levels and continua of the excited A
[singlet Sigma u +] and B [singlet Pi u] electronic states. Theoretical and
experimental data are used to characterize the molecular properties taking
advantage of knowledge recently obtained from photoassociation spectroscopy and
ultra-cold atom collision studies. The quantum-mechanical calculations are
carried out for temperatures in the range from 1000 to 2000 K and are compared
with previous calculations and measurements.Comment: 20 pages, revtex, epsf, 6 fig
Testing real-time systems using TINA
The paper presents a technique for model-based black-box conformance testing of real-time systems using the Time Petri Net Analyzer TINA. Such test suites are derived from a prioritized time Petri net composed of two concurrent sub-nets specifying respectively the expected behaviour of the system under test and its environment.We describe how the toolbox TINA has been extended to support automatic generation of time-optimal test suites. The result is optimal in the sense that the set of test cases in the test suite have the shortest possible accumulated time to be executed. Input/output conformance serves as the notion of implementation correctness, essentially timed trace inclusion taking environment assumptions into account. Test cases selection is based either on using manually formulated test purposes or automatically from various coverage criteria specifying structural criteria of the model to be fulfilled by the test suite. We discuss how test purposes and coverage criterion are specified in the linear temporal logic SE-LTL, derive test sequences, and assign verdicts
The Indignados protests in the Spanish and Greek press: Moving beyond the âprotest paradigmâ?
Continuous-flow in-line solvent-swap crystallization of vitamin D(3)
A continuous tandem in-line evaporationâcrystallization is presented. The process includes an in-line solvent-swap step, suitable to be coupled to a capillary based cooler. As a proof of concept, this setup is tested in a direct in-line acetonitrile mediated crystallization of Vitamin Dâ. This configuration is suitable to be coupled to a new end-to-end continuous microflow synthesis of Vitamin Dâ. By this procedure, vitamin particles can be crystallized in continuous flow and isolated using an in-line continuous filtration step. In one run in just 1 min of cooling time, âŒ50% (w/w) crystals of Vitamin Dâ are directly obtained. Furthermore, the polymorphic form as well as crystals shape and size properties are described in this paper.Marc EscribĂ -Gelonch, Volker Hessel, Manuel C. Maier, Timothy NoĂ«l, Maria Fernanda Neira dâAngelo and Heidrun Gruber-Woelfle
The Eurotower Strikes Back
The 2008 global financial crisis came with fearsâand, for some, hopesâthat a new wave of public mobilization would emerge in industrialized countries. Especially throughout the European Union (EU), the epicenter of the crisis, large protests were expected. Yet, the energy with which social groups mobilized against the proposed austerity measures quickly fizzled. This article provides new evidence for why this was the case. In line with Neo-Keynesian theory, we argue that the interest rate adjustments and political announcements of the European Central Bank (ECB) limited the potential for mass unrest in the member states of the Economic and Monetary Union (EMU) affected by the crisis. We provide evidence for our argument with yearly panel data and a new original data set of monthly political protests between 2001 and 2013. Our analyses support the hypothesis that the ECB was able to successfully assuage dissatisfaction with the limited reform options of the Eurozone member states in the wake of the Eurocrisis
Manual versus automatic bladder wall thickness measurements: a method comparison study
Purpose
To compare repeatability and agreement of conventional ultrasound bladder wall thickness (BWT) measurements with automatically obtained BWT measurements by the BVM 6500 device.
Methods
Adult patients with lower urinary tract symptoms, urinary incontinence, or postvoid residual urine were urodynamically assessed. During two subsequent cystometry sessions the infusion pump was temporarily stopped at 150 and 250 ml bladder filling to measure BWT with conventional ultrasound and the BVM 6500 device. For each method and each bladder filling, repeatability and variation was assessed by the method of Bland and Altman.
Results
Fifty unselected patients (30 men, 20 women) aged 21â86 years (median 62.5 years) were prospectively evaluated. Invalid BWT measurements were encountered in 2.1â14% of patients when using the BVM 6500 versus 0% with conventional ultrasound (significant only during the second measurement at 150 ml bladder filling). Mean difference in BWT values between the measurements of one technique was -0.1 to +0.01 mm. Measurement variation between replicate measurements was smaller for conventional ultrasound and the smallest for 250 ml bladder filling. Mean difference between the two techniques was 0.11â0.23 mm and did not differ significantly. The BVM 6500 device was not able to correctly measure BWTs above 4 mm.
Conclusions
Both BWT measurements are repeatable and agree with each other. However, conventional ultrasound measurements have a smaller measurement variance, can measure BWT in all patients, and BWTs above 4 mm
ââThe outraged youngâ: young Europeans, civic engagement and the new media in a time of crisisâ
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