Form Factors for Quasi-particles in c=1 Conformal Field Theory

The non-Fermi liquid physics at the edge of fractional quantum Hall systems is described by specific chiral Conformal Field Theories with central charge c=1. The charged quasi-particles in these theories have fractional charge and obey a form of fractional statistics. In this paper we study form factors, which are matrix elements of physical (conformal) operators, evaluated in a quasi-particle basis that is organized according to the rules of fractional exclusion statistics. Using the systematics of Jack polynomials, we derive selection rules for a special class of form factors. We argue that finite temperature Green's functions can be evaluated via systematic form factor expansions, using form factors such as those computed in this paper and thermodynamic distribution functions for fractional exclusion statistics. We present a specific case study where we demonstrate that the form factor expansion shows a rapid convergence.Comment: 36 pages, 1 postscript figur

Quasi-particles for quantum Hall edges

We discuss a quasi-particle formulation of effective edge theories for the fractional quantum Hall effect. Fundamental quasi-particles for the Laughlin state with filling fraction \nu =1/3 are edge electrons of charge -e and edge quasi-holes of charge +e/3. These quasi-particles satisfy exclusion statistics in the sense of Haldane. We exploit algebraic properties of edge electrons to derive a kinetic equation for charge transport between a \nu=1/3 fractional quantum Hall edge and a normal metal.Comment: Latex, 6 pages, Contribution to the proceedings of the XXXIVth Rencontres de Moriond `Quantum Physics at Mesoscopic Scale

Short and random: Modelling the effects of (proto-)neural elongations

To understand how neurons and nervous systems first evolved, we need an account of the origins of neural elongations: Why did neural elongations (axons and dendrites) first originate, such that they could become the central component of both neurons and nervous systems? Two contrasting conceptual accounts provide different answers to this question. Braitenberg's vehicles provide the iconic illustration of the dominant input-output (IO) view. Here the basic role of neural elongations is to connect sensors to effectors, both situated at different positions within the body. For this function, neural elongations are thought of as comparatively long and specific connections, which require an articulated body involving substantial developmental processes to build. Internal coordination (IC) models stress a different function for early nervous systems. Here the coordination of activity across extended parts of a multicellular body is held central, in particular for the contractions of (muscle) tissue. An IC perspective allows the hypothesis that the earliest proto-neural elongations could have been functional even when they were initially simple short and random connections, as long as they enhanced the patterning of contractile activity across a multicellular surface. The present computational study provides a proof of concept that such short and random neural elongations can play this role. While an excitable epithelium can generate basic forms of patterning for small body-configurations, adding elongations allows such patterning to scale up to larger bodies. This result supports a new, more gradual evolutionary route towards the origins of the very first full neurons and nervous systems.Comment: 12 pages, 5 figures, Keywords: early nervous systems, neural elongations, nervous system evolution, computational modelling, internal coordinatio

Metal sources for the Katanga Copperbelt deposits (DRC) insights from Sr and Nd isotope ratios

The ore deposits of the Central African Copperbelt formed during a multiphase mineralisation process. The basement underlying the Neoproterozoic Katanga Supergroup that hosts the ore, demonstrates the largest potential as metal source. Various ore deposits that formed during different mineralisation phases are taken as case studies, i.e. Kamoto, Luiswishi, Kambove West, Dikulushi and Kipushi (Democratic Republic of Congo, DRC). The Sr and Nd isotopic compositions of gangue carbonates associated with these deposits is determined and compared with those of rocks from several basement units, bordering or underlying the Copperbelt, to infer the metal sources. The mineralising fluid of diagenetic stratiform Cu-Co mineralisation interacted with felsic basement rocks underlying the region. The Co from these deposits is most likely derived from mafic rocks, but this is not observed in the isotopic signatures. Syn-orogenic, stratabound Cu-Co mineralisation resulted mainly from remobilisation of diagenetic sulphides. A limited, renewed contribution of metals from felsic basement rocks might be indicated by the isotope ratios in the western part of the Copperbelt, where the metamorphic grade is the lowest. The mineralising fluid of syn- and post-orogenic, vein-type mineralisations interacted with local mafic rocks, and with felsic basement or siliciclastic host rocks

Modeling spontaneous activity across an excitable epithelium: Support for a coordination scenario of early neural evolution

Internal coordination models hold that early nervous systems evolved in the first place to coordinate internal activity at a multicellular level, most notably the use of multicellular contractility as an effector for motility. A recent example of such a model, the skin brain thesis, suggests that excitable epithelia using chemical signaling are a potential candidate as a nervous system precursor.We developed a computational model and a measure for whole body coordination to investigate the coordinative properties of such excitable epithelia. Using this measure we show that excitable epithelia can spontaneously exhibit body-scale patterns of activation. Relevant factors determining the extent of patterning are the noise level for exocytosis, relative body dimensions, and body size. In smaller bodies whole-body coordination emerges from cellular excitability and bidirectional excitatory transmission alone.Our results show that basic internal coordination as proposed by the skin brain thesis could have arisen in this potential nervous system precursor, supporting that this configuration may have played a role as a proto-neural system and requires further investigation

Measuring body satisfaction in women with eating disorders and healthy women:appearance-related and functional components in the Body Cathexis Scale (Dutch version)

Purpose Differentiating the concept of body satisfaction, especially the functional component, is important in clinical and research context. The aim of the present study is to contribute to further refinement of the concept by evaluating the psychometric properties of the Dutch version of the Body Cathexis Scale (BCS). Differences in body satisfaction between clinical and non-clinical respondents are also explored. Method Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used to investigate whether functional body satisfaction can be distinguished as a separate factor, using data from 238 adult female patients from a clinical sample and 1060 women from two non-clinical samples in the Netherlands. Univariate tests were used to identify differences between non-clinical and clinical samples. Results EFA identified functionality as one of three factors, which was confirmed by CFA. CFA showed the best fit for a three-factor model, where functionality, non-weight, and weight were identified as separate factors in both populations. Internal consistency was good and correlations between factors were low. Women in the non-clinical sample scored significantly higher on the BCS than women with eating disorders on all three subscales, with high effect sizes. Conclusions The three factors of the BCS may be used as subscales, enabling researchers and practitioners to use one scale to measure different aspects of body satisfaction, including body functionality. Use of the BCS may help to achieve a more complete understanding of how people evaluate body satisfaction and contribute to further research on the effectiveness of interventions focussing on body functionality

Shifting the Focus:A Pilot Study on the Effects of Positive Body Exposure on Body Satisfaction, Body Attitude, Eating Pathology and Depressive Symptoms in Female Patients with Eating Disorders

One of the most commonly used techniques for the treatment of body image problems in eating disorders (ED) is body exposure (BE). However, evidence of its effectiveness in clinical populations is scarce. In the Positive Body Experience (PBE) protocol, the focus of positive BE is on aesthetic, functional and tactile aspects of the body. The current study evaluates the outcomes of positive BE with regard to changes in attitudinal body image and eating pathology, as well as the factors that influence these changes, in a sample of 84 adult female patients with different EDs who did not receive any other treatment for their EDs during the period in which BE treatment occurred. The results show significant positive changes in attitudinal body image, ED behaviors and depressive symptoms, with depressive symptoms at baseline mediating the changes in attitudinal body image. This study indicates that the PBE protocol is a suitable intervention for reducing negative attitudinal body image in anorexia and bulimia nervosa patients, as well as those with binge eating disorder. Furthermore, the results suggest that positive non-weight-related and functional body satisfaction are strong catalysts for change and that depressive symptoms play an important role in the ability to change. Additional RCTs are needed to gain more insight into the effects of PBE