Geometric Phases in Graphitic Cones

In this article we use a geometric approach to study geometric phases in graphitic cones. The spinor that describes the low energy states near the Fermi energy acquires a phase when transported around the apex of the cone, as found by a holonomy transformation. This topological result can be viewed as an analogue of the Aharonov-Bohm effect. The topological analysis is extended to a system with $n$ cones, whose resulting configuration is described by an effective defect.Comment: 4 pages, revtex

Fractionalization patterns in strongly correlated electron systems: Spin-charge separation and beyond

We discuss possible patterns of electron fractionalization in strongly interacting electron systems. A popular possibility is one in which the charge of the electron has been liberated from its Fermi statistics. Such a fractionalized phase contains in it the seed of superconductivity. Another possibility occurs when the spin of the electron, rather than its charge, is liberated from its Fermi statistics. Such a phase contains in it the seed of magnetism, rather than superconductivity. We consider models in which both of these phases occur and study possible phase transitions between them. We describe other fractionalized phases, distinct from these, in which fractions of the electron themselves fractionalize, and discuss the topological characterization of such phases. These ideas are illustrated with specific models of p-wave superconductors, Kondo lattices, and coexistence between d-wave superconductivity and antiferromagnetism.Comment: 28 pages, 11 fig

Analysis of the signal transfer and folding in N-Path filters with a series inductance

N-path filters exploiting switched-series-R-C networks can realize high-Q blocking-tolerant band-pass filters. Moreover, their center frequency is flexibly programmable by a digital clock. Unfortunately, the time variant nature of these circuits also results in unwanted signal folding. This paper proves analytically that folding can be reduced and band pass filtering can be improved by adding an inductance in series with the switched-R-C network. In contrast, a shunt capacitor degrades band-pass filter performance. The interaction between the reactive series impedance and the switched capacitors of an N-path filter complicates analysis due to memory effects associated with reactive components. Assuming $N$ identical signal paths with 1/$N$ duty cycle, we show it is possible to solve the set of differential equations, by assuming that the signals in each path only differ in delay. Analytical equations are verified versus simulations, and the benefits in filter properties and reduction in signal folding are demonstrated

An Ergonomic Evaluation of Douglas Fir Manual Pruning in New Zealand

This report summarizes the findings of an ergonomie evaluation of first lift manual pruning of Douglas fir under New Zealand plantation forestry conditions. Six subjects were each observed undertaking their normal work methods throughout their complete working day. Heart rate data were collected and analysed using several heart rate indices in order to determine the workload of first lift pruning. The average working heart rate was 112 bt.min"1 ± 10.6 (SD). Results indicate first lift pruning to be a moderate to heavy workload activity. The manual pruning work method may place severe pressures on the workers' tendons, related bones and nerves of the hand, wrist, and elbow. Alternative pruning methods may contain inherent health and safety risks which must be carefully considered by those involved in the occupation of professional tree pruning

Inter- and Intra-Observer Variability and the Effect of Experience in Cine-MRI for Adhesion Detection.

Cine-MRI for adhesion detection is a promising novel modality that can help the large group of patients developing pain after abdominal surgery. Few studies into its diagnostic accuracy are available, and none address observer variability. This retrospective study explores the inter- and intra-observer variability, diagnostic accuracy, and the effect of experience. A total of 15 observers with a variety of experience reviewed 61 sagittal cine-MRI slices, placing box annotations with a confidence score at locations suspect for adhesions. Five observers reviewed the slices again one year later. Inter- and intra-observer variability are quantified using Fleiss' (inter) and Cohen's (intra) κ and percentage agreement. Diagnostic accuracy is quantified with receiver operating characteristic (ROC) analysis based on a consensus standard. Inter-observer Fleiss' κ values range from 0.04 to 0.34, showing poor to fair agreement. High general and cine-MRI experience led to significantly (p < 0.001) better agreement among observers. The intra-observer results show Cohen's κ values between 0.37 and 0.53 for all observers, except one with a low κ of -0.11. Group AUC scores lie between 0.66 and 0.72, with individual observers reaching 0.78. This study confirms that cine-MRI can diagnose adhesions, with respect to a radiologist consensus panel and shows that experience improves reading cine-MRI. Observers without specific experience adapt to this modality quickly after a short online tutorial. Observer agreement is fair at best and area under the receiver operating characteristic curve (AUC) scores leave room for improvement. Consistently interpreting this novel modality needs further research, for instance, by developing reporting guidelines or artificial intelligence-based methods