Long-Wavelength Anomalies in the Asymptotic Behavior of Mode-Coupling Theory

We discuss the dynamic behavior of a tagged particle close to a classical localization transition in the framework of the mode-coupling theory of the glass transition. Asymptotic results are derived for the order parameter as well as the dynamic correlation functions and the mean-squared displacement close to the transition. The influence of an infrared cutoff is discussed.Comment: 15 pages, 8 figures, to appear in J Phys Condens Matte

Origin of Rashba-splitting in the quantized subbands at Bi2Se3 surface

We study the band structure of the $\text{Bi}_2\text{Se}_3$ topological insulator (111) surface using angle-resolved photoemission spectroscopy. We examine the situation where two sets of quantized subbands exhibiting different Rashba spin-splitting are created via bending of the conduction (CB) and the valence (VB) bands at the surface. While the CB subbands are strongly Rashba spin-split, the VB subbands do not exhibit clear spin-splitting. We find that CB and VB experience similar band bending magnitudes, which means, a spin-splitting discrepancy due to different surface potential gradients can be excluded. On the other hand, by comparing the experimental band structure to first principles LMTO band structure calculations, we find that the strongly spin-orbit coupled Bi 6$p$ orbitals dominate the orbital character of CB, whereas their admixture to VB is rather small. The spin-splitting discrepancy is, therefore, traced back to the difference in spin-orbit coupling between CB and VB in the respective subbands' regions

Evolution of edge states in topological superfluids during the quantum phase transition

The quantum phase transition between topological and non-topological insulators or between fully gapped superfluids/superconductors can occur without closing the gap. We consider the evolution of the Majorana edge states on the surface of topological superconductor during transition to the topologically trivial superconductor on example of non-interacting Hamiltonian describing the spin-triplet superfluid 3He-B. In conventional situation when the gap is nullified at the transition, the spectrum of Majorana fermions shrinks and vanishes after the transition to the trivial state. If the topological transition occurs without the gap closing, the Majorana fermion spectrum disappears by escaping to ultraviolet, where Green's function approaches zero. This demonstrates the close connection between the topological transition without closing the gap and zeroes in the Green's function. Similar connection takes place in interacting systems where zeroes may occur due to interaction.Comment: 5 pages, 2 figures, JETP Letters style, version submitted to JETP Letter

Assessment of occlusive arterial disease of abdominal aorta and lower extremities arteries: value of multidetector CT angiography using an adaptive acquisition method

We evaluated 16-detector-row CT in the assessment of occlusive peripheral arterial disease (PAD) of the abdominal aorta and lower extremities using an adaptive method of acquisition to optimise arterial enhancement especially for the distal foot arteries. Thirty-four patients underwent transcatheter angiography (TCA) and CT angiography within 15days. For each patient, table speed and rotation were selected according to the calculated optimal transit time of contrast material obtained after a single bolus test and two dynamic acquisitions at aorta and popliteal arteries. Analysis included image quality and detection of stenosis equal or greater than 50% on a patient basis and on an arterial segment basis. Sensitivity and specificity of CT were calculated with the TCA considered as the standard of reference. CT was conclusive in all segments with no technical failures even in difficult cases with occluded bypasses and aneurysms. On patient-basis analysis, the overall sensitivity and specificity to detect significant stenosis greater than 50% were both 100%. Segmental analysis shows high values of sensitivity and specificity ranging from 91 to 100% and from 81 to 100%, respectively, including distal pedal arteries. Sixteen-detector-row CT angiography using an adaptive acquisition improves the image quality and provides a reliable non-invasive technique to assess occlusive peripheral arterial disease, including distal foot arterie

Orchestrating Cultural Heritage:Exploring the Automated Analysis and Organization of Charles S. Peirce's PAP Manuscript

This preliminary study introduces an innovative approach to the analysis and organization of cultural heritage materials, focusing on the archive of Charles S. Peirce. Given the diverse range of artifacts, objects, and documents comprising cultural heritage, it is essential to efficiently organize and provide access to these materials for the wider public. However, Peirce's manuscripts pose a particular challenge due to their extensive quantity, which makes comprehensive organization through manual classification practically impossible. In response to this challenge, our paper proposes a methodology for the automated analysis and organization of Peirce's manuscripts. We have specifically tested this approach on the renowned 115-page manuscript known as PAP. This study represents a significant step forward in establishing a research direction for the development of a larger project. By incorporating novel computational methods, this larger project has the potential to greatly enhance the field of cultural heritage organization

Electronic and phononic Raman scattering in detwinned YBa2_2Cu3_3O6.95_{6.95} and Y0.85_{0.85}Ca0.15_{0.15}Ba2_2Cu3_3O6.95_{6.95}: s-wave admixture to the dx2−y2d_{x^2-y^2}-wave order parameter

Inelastic light (Raman) scattering has been used to study electronic excitations and phonon anomalies in detwinned, slightly overdoped YBa$_2$Cu$_3$O$_{6.95}$ and moderately overdoped Y$_{0.85}$Ca$_{0.15}$Ba$_2$Cu$_3$O$_{6.95}$ single crystals. In both samples modifications of the electronic pair-breaking peaks when interchanging the a- and b-axis were observed. The lineshapes of several phonon modes involving plane and apical oxygen vibrations exhibit pronounced anisotropies with respect to the incident and scattered light field configurations. Based on a theoretical model that takes both electronic and phononic contributions to the Raman spectra into account, we attribute the anisotropy of the superconductivity-induced changes in the phonon lineshapes to a small s-wave admixture to the $d_{x^2-y^2}$ pair wave-function. Our theory allows us to disentangle the electronic Raman signal from the phononic part and to identify corresponding interference terms. We argue that the Raman spectra are consistent with an s-wave admixture with an upper limit of 20 percent.Comment: accepted in Phys. Rev. B, 11 page

Euclidean Greedy Drawings of Trees

Greedy embedding (or drawing) is a simple and efficient strategy to route messages in wireless sensor networks. For each source-destination pair of nodes s, t in a greedy embedding there is always a neighbor u of s that is closer to t according to some distance metric. The existence of greedy embeddings in the Euclidean plane R^2 is known for certain graph classes such as 3-connected planar graphs. We completely characterize the trees that admit a greedy embedding in R^2. This answers a question by Angelini et al. (Graph Drawing 2009) and is a further step in characterizing the graphs that admit Euclidean greedy embeddings.Comment: Expanded version of a paper to appear in the 21st European Symposium on Algorithms (ESA 2013). 24 pages, 20 figure

Stomatal conductance limited the CO2 response of grassland in the last century

The anthropogenic increase of atmospheric CO2 concentration (ca) is impacting carbon (C), water and nitrogen (N) cycles in grassland and other terrestrial biomes. Plant canopy stomatal conductance is a key player in these coupled cycles: it is a physiological control of vegetation water-use efficiency (the ratio of C gain by photosynthesis to water loss by transpiration), and it responds to photosynthetic activity, which is influenced by vegetation N status. It is unknown if the ca-increase and climate change over the last century have already affected canopy stomatal conductance and its links with C and N processes in grassland. Results: Here, we assessed two independent proxies of (growing season-integrating canopy-scale) stomatal conductance changes over the last century: trends of δ18O in cellulose (δ18Ocellulose) in archived herbage from a wide range of grassland communities on the Park Grass Experiment at Rothamsted (U.K.), and changes of the ratio of yields to the CO2 concentration gradient between the atmosphere and the leaf internal gas space (ca – ci). The two proxies correlated closely (R2=0.70), in agreement with the hypothesis. In addition, the sensitivity of δ18Ocellulose-changes to estimated stomatal conductance changes agreed broadly with published sensitivities across a range of contemporary field and controlled environment studies, further supporting the utility of δ18Ocellulose-changes for historical reconstruction of stomatal conductance changes at Park Grass. Trends of δ18Ocellulose differed strongly between plots and indicated much greater reductions of stomatal conductance in grass-rich than dicot-rich communities. Reductions of stomatal conductance were connected with reductions of yield trends, nitrogen acquisition and nitrogen nutrition index. Although all plots were nitrogen-limited or phosphorus- and nitrogen-co-limited to different degrees, long-term reductions of stomatal conductance were largely independent of fertilizer regimes and soil pH, except for nitrogen fertilizer supply which promoted the abundance of grasses