Breakdown of Hydrodynamics in the Classical ID Heisenberg Model

Extensive spin‐dynamics simulations have been performed to study the dynamical behavior of the classical Heisenberg chain at infinite temperatures and long wavelengths. We find that the energy and spin show distinctly different dynamics in the isotropic system. The energy correlation function follows the classical diffusion theory prediction, namely, it decays exponentially with q 2 t. In contrast, the spin correlation function is found to decay exponentially as q 2.12 t ln t implying a logarithmically divergent diffusion constant and the failure of the usual hydrodynamic assumptions

Alternative antibody for the detection of CA19-9 antigen: a European multicenter study for the evaluation of the analytical and clinical performance of the Access (R) GI Monitor assay on the UniCel (R) Dxl 800 Immunoassay System

Background: Gastrointestinal cancer antigen CA19-9 is known as a valuable marker for the management of patients with pancreatic cancer. Methods: The analytical and clinical performance of the Access(R) GI Monitor assay (Beckman Coulter) was evaluated on the UniCel(R) Dxl 800 Immunoassay System at five different European sites and compared with a reference method, defined as CA19-9 on the Elecsys System (Roche Diagnostics). Results: Total imprecision (%CV) of the GI Monitor ranged between 3.4% and 7.7%, and inter-laboratory reproducibility between 3.6% and 4.0%. Linearity upon dilution showed a mean recovery of 97.4% (SD+7.2%). Endogenous interferents had no influence on GI Monitor levels (mean recoveries: hemoglobin 103%, bilirubin 106%, triglycerides 106%). There was no high-dose hook effect up to 115,000 kU/L. Clinical performance investigated in sera from 1811 individuals showed a good correlation between the Access' GI Monitor and Elecsys CA19-9 (R = 0.959, slope = 1.004, intercept +0.17). GI Monitor serum levels were low in healthy individuals (n = 267, median = 6.0 kU/L, 95th percentile = 23.1 kU/L), higher in individuals with various benign diseases (n = 550, medians = 5.8-13.4 kU/L, 95th percentiles = 30.1-195.5 kU/L) and even higher in individuals suffering from various cancers (n = 995, medians = 8.4-233.8 kU/L, 95th percentiles = 53.7-13,902 kU/L). Optimal diagnostic accuracy for cancer detection against the relevant benign control group by the GI Monitor was found for pancreatic cancer {[}area under the curve (AUC) 0.83]. Results for the reference CA19-9 assay were comparable (AUC 0.85). Conclusions: The Access(R) GI Monitor provides very good methodological characteristics and demonstrates an excellent analytical and clinical correlation with the Elecsys CA19-9. The GI Monitor shows the best diagnostic accuracy in pancreatic cancer. Our results also suggest a clinical value of the GI Monitor in other cancers

Exploring Asynchronous Brainstorming in Large Groups: A Field Comparison of Serial and Parallel Subgroups

Objective: To compare the results of two different modes of using multiple groups (instead of one large group) in order to identify problems and develop solutions. Background: Many of the complex problems facing organizations today require the use of very large groups or collaborations of groups from multiple organizations. There are many logistical problems associated with the use of such large groups including the ability to bring everyone together at the same time and location. Methods: A field study involving two different organizations, comparing productivity and satisfaction of group. The approaches included a) multiple small groups, each completing the entire process from start to end, and combining the results at the end (Parallel mode); and b) multiple subgroups, each building on the work provided by previous subgroups (Serial mode). Results: Groups using the serial mode produced more elaborations compared to parallel groups, whereas parallel groups produced more unique ideas compared to the serial groups. No significant differences were found related to satisfaction with process and outcomes between the two modes. Conclusion: Preferred mode depends on the type of task facing the group. Parallel groups are more suited for tasks where a variety of new ideas are needed, whereas serial groups are best suited when elaboration and in depth thinking on the solution are required. Application: Results of this research can guide the development of facilitated sessions of large groups or ‘teams of teams’

Reading the orbital angular momentum of light using plasmonic nanoantennas

Orbital angular momentum of light has recently been recognized as a new degree of freedom to encode information in quantum communication using light pulses. Methods to extract this information include reversing the process by which such twisted light was created in the first place or interference with other beams. Here we propose an alternative new way to directly read out the extra information encoded in twisted light using plasmonic nanoantennas by converting the information about the orbital angular momentum of light into spectral information using bright and dark modes. Exemplarily considering rotation-symmetric nanorod nanoantennas, we show that their scattering cross section is sensitive to the value of the orbital angular momentum combined with the polarization of an incident twisted light beam. Explaining the twist dependence of the excited modes with a new analytical model, our results pave the way to twisted light nanoplasmonics, which is of central importance for future on-chip communication using orbital angular momentum of light

Self-Consistent Born Approximation for the Hole Motion in the Three-Band Model: a Comparison with Photoemission Experiments

The dispersion relation of the single hole in the CuO2 plane is calculated in the self-consistent Born approximation for the three-band Hamiltonian. We find that direct oxygen-oxygen hopping removes the strong anisotropy of the hole spectrum around the band minima. Our results compare well with recent photoemission measurements of the single-hole dispersion relation in Sr2CuO2Cl2

Quasiparticle excitations in frustrated antiferromagnets

We have computed the quasiparticle wave function corresponding to a hole injected in a triangular antiferromagnet. We have taken into account multi-magnon contributions within the self consistent Born approximation. We have found qualitative differences, under sign reversal of the integral transfer t, regarding the multi-magnon components and the own existence of the quasiparticle excitations. Such differences are due to the subtle interplay between magnon-assisted and free hopping mechanisms. We conclude that the conventional quasiparticle picture can be broken by geometrical frustration without invoking spin liquid phases.Comment: 5 pages, 4 figures, presented at " At the Frontiers of the condensed Matter II, Buenos Aires. June, 2004 ". To be published in Physica