The Density Matrix Renormalization Group Method applied to Interaction Round a Face Hamiltonians

Given a Hamiltonian with a continuous symmetry one can generally factorize that symmetry and consider the dynamics on invariant Hilbert Spaces. In Statistical Mechanics this procedure is known as the vertex-IRF map, and in certain cases, like rotational invariant Hamiltonians, can be implemented via group theoretical techniques. Using this map we translate the DMRG method, which applies to 1d vertex Hamiltonians, into a formulation adequate to study IRF Hamiltonians. The advantage of the IRF formulation of the DMRG method ( we name it IRF-DMRG), is that the dimensions of the Hilbert Spaces involved in numerical computations are smaller than in the vertex-DMRG, since the degeneracy due to the symmetry has been eliminated. The IRF-DMRG admits a natural and geometric formulation in terms of the paths or string algebras used in Exactly Integrable Systems and Conformal Field Theory. We illustrate the IRF-DMRG method with the study of the SOS model which corresponds to the spin 1/2 Heisenberg chain and the RSOS models with Coxeter diagram of type A, which correspond to the quantum group invariant XXZ chain.Comment: 22 pages, Latex, 18 figures in Postscript file

Kinorhynch diversity in the southern Gulf of Mexico and a description of Dracoderes chaac sp. nov.

Sediment collections from the southern Gulf of Mexico between the Texas—Mexico border and the Yucatán Peninsula have resulted in many new kinorhynch species distribution records and the finding and taxonomic description of a new species, Dracoderes chaac sp. nov. This study focused on the non—echinoderid members of the Phylum Kinorhyncha, many of which are rare or restricted to only a few locations. A total of 136 specimens were identified from 24 sediment stations, distributed among the following species: Antygomonas gwenae, Campyloderes vanhoeffeni, Centroderes readae, Condyloderes flosfimbriatus, Co. rohalorum, Cristaphyes panamensis, Dracoderes chaac sp. nov., Leiocanthus corrugatus, L. langi, L. quinquenudus, L. satanicus, Pycnophyes alexandroi, Semnoderes lusca, and Sphenoderes aspidochelone. Additional undescribed species in the genera Leiocanthus, Mixtophyes, and Paracentrophyes were recovered. Statistical analysis of the stations revealed a grouping of locations where the majority of the pycnophyid species were recovered. Some species (e.g., Ca. vanhoeffeni, S. aspidochelone) had an extensive distribution, while others were recorded from one or few locations only (e.g., A. gwenae, Co. rohalorum). Most of the species were reported from earlier collections in the northern Gulf of Mexico on the U.S. continental shelf, between 700–1100 km away

Evaluation of the performance of self-healing concrete at small and large scale under laboratory conditions

HEALCON is an EU-FP7 project which aims to develop self-healing concrete to create durable and sustainable concrete structures. While during the first years of the project the self-healing materials (including the healing agents and suitable encapsulation methodologies) and monitoring techniques were designed and tested at lab-scale, large scale elements have been tested near the end of the project to verify the feasibility and efficiency of the self-healing concrete under conditions closer to reality. For this paper, two types of healing agents were investigated for use in mortar and concrete. The first type of healing agent studied was a coated superabsorbent polymer (C-SAP). It is known that the autogenous healing capacity is increased by incorporation of superabsorbent polymers (SAPs) in mortar/concrete. The agents present in the crack can absorb intruding water, swell and block the crack, leading to immediate sealing, but can also exude moisture to the surrounding concrete environment stimulating healing of the concrete by hydration of unreacted cement particles or by CaCO3 precipitation. The disadvantage of these SAPs in the fresh mortar/concrete mix is however that they absorb large quantities of mixing water, leading to unwanted effects (e.g. loss of workability and macro-pore formation). By coating of the SAPs, we want to eliminate this disadvantage. The fluid bed spraying of the different layers was applied by VTT. A second healing agent studied, is a biogenic healing agent, namely a Mixed Ureolytic Culture (MUC). This type of healing agent was developed by Avecom in order to reduce the cost associated with the production of pure bacterial strains. This mixed ureolytic culture is moreover self-protecting and does not need any further encapsulation. At first, the performance of the healing agents itself was evaluated. For the coated SAPs, the swelling performance and swelling rate were determined, showing that the coating can limit the uptake of water during the first 10-15 minutes. For the MUC, the ureolytic and CaCO3 precipitating capacity was determined, immediately after production of the MUC and after 3 months of storage. The results show the potential of these mixed cultures to be used as self-healing agent in mortar/concrete, but also show a decrease of their effectiveness with time. Subsequently, the healing agents were incorporated in mortar mixes at UGent. A dosage of 1 wt% relative to the cement content caused a large reduction of the mechanical properties of the mortar (up to ~ 50%), except for the coated SAP. The sealing efficiency was evaluated with the water flow test, as designed by one of the project partners in HEALCON. The performance of reference mixes was compared to that of self-healing mixes with SAP, coated SAP or MUC (+ urea). Results showed that for cracks with a width less than 0.150 mm, all mortars were sealed (almost) completely after storage for 28 days in wet-dry environment (12 h wet – 12 h dry) after crack creation. For cracks with a larger width, differences were noticed between the different specimens. Moreover, also the immediate sealing effect induced by the presence of SAPs could be noticed. It has to be noted however that the crack width plays an important role but is varying along the crack length (within a specimen) and between specimens, making the analysis more difficult. In order to extend the application to concrete, self-healing and reference reinforced concrete beams (2500 x 400 x 200 mm) were produced at the Danish Technological Institute. The self-healing concretes contained coated SAPs or MUC. Moreover, the beams were equipped with corrosion sensors that are connected to a wireless monitoring system, developed by the Technology-Transfer- Initiative at the University of Stuttgart. The multi reference electrodes (MuRE) were installed alongside the reinforcements and measure the corrosion potential at certain positions. Data is collected in sufficiently dense intervals by battery powered nodes that transmit the data wirelessly to a base station and further on to a database where it can be accessed through a web based application for data analysis over the internet. At the age of 28 days, three-point bending cracks up to 0.6 mm were created in the beams. Subsequently, the beams were regularly sprayed with water (four times one hour per day) for 6 weeks and afterwards, the beams were, once a week, exposed to 3 wt% NaCl solution for 24 h. Evaluation of the self-healing performance by microscopic analysis (crack microscopy and analysis of thin sections) showed that for the reference beam and beam with MUC no significant healing could be noticed (probably because of insufficient supply of nutrients for the bacteria). For the beams with coated SAPs, the smaller cracks (0.1 and 0.2 mm) were partly closed. Continuous corrosion monitoring showed corrosion in the reference and MUC beams already after the first exposure to NaCl solution. Onset of corrosion was delayed in the case the beams contained coated SAPs

Breast asymmetry analysis employing tree-structured wavelet transform

Statistically distributed developmental asymmetries appearing in paired body structures such as breasts in women are usually related to unhealthy biological conditions. In particular, there is evidence that breast cancer patients show more breast dimensional asymmetries and larger breasts than age-matched healthy women. It was also recently reported the application of Gabor nonorthogonal wavelets filtering for analyzing asymmetries of the directional structures appearing in mammograms corresponding to healthy and breast cancer patients. In this paper the Tree-Structured Wavelet Transform, which uses orthogonal wavelet bases, is applied for the first time in order to quantify texture asymmetries between left- and right- mammograms in women. In order to assess the suitability of the method, it was applied to characterize breast asymmetries of mammograms corresponding to a small population of 63 healthy women with ages ranging between 30 and 70 years. The obtained results justify further improvements of this method and its application for correlating asymmetries and the predisposition to breast cancer.Eje: Aplicaciones biomédicasRed de Universidades con Carreras en Informática (RedUNCI

Environmental determinism of year to year recruitment variability of European eel in a small coastal catchment, the Frémur river, north-west France

The influence of environmental factors (mainly the river flow) on the year-to-year variability of European eel Anguilla anguilla fluvial recruitment in a small coastal River (north-west France) was examined. A comprehensive survey of catches from fixed traps at two weirs located at 4·5 km (Pont es Omnes Dam) and 6·0 km (Bois Joli Dam) above the river mouth was carried out between 1997 and 2004. Young pigmented elvers (mean ± s.d. total length, 133·7 ± 29·6 mm) were recruited in eel-passes from February to October, but the main runs followed a modal curve from April to September with a peak centred in May to June. Catches varied greatly between years, from 381 to 26 765 elvers. For each trap, a positive linear relationship between monthly mean river flow that preceded the maximal intensity of captures and annual total catches was observed. These relationships explained 73·1% (P <0.01) and 89·0% (P <0.001) of the year-to-year variability of the recruitment observed in the Pont es Omnes and Bois Joli traps respectively. A significant increase in river flow at the beginning of the migration peak would thus trigger a greater proportion of A. anguilla settled in the estuary and in the downstream zone of the Fremur River to begin their freshwater colonization. The physicochemical roles of changes in river discharge in stimulating upstream migration are discussed. It is concluded that fluvial recruitment in the Fremur River is mainly determined by environmental factors

The scattering from generalized Cantor fractals

We consider a fractal with a variable fractal dimension, which is a generalization of the well known triadic Cantor set. In contrast with the usual Cantor set, the fractal dimension is controlled using a scaling factor, and can vary from zero to one in one dimension and from zero to three in three dimensions. The intensity profile of small-angle scattering from the generalized Cantor fractal in three dimensions is calculated. The system is generated by a set of iterative rules, each iteration corresponding to a certain fractal generation. Small-angle scattering is considered from monodispersive sets, which are randomly oriented and placed. The scattering intensities represent minima and maxima superimposed on a power law decay, with the exponent equal to the fractal dimension of the scatterer, but the minima and maxima are damped with increasing polydispersity of the fractal sets. It is shown that for a finite generation of the fractal, the exponent changes at sufficiently large wave vectors from the fractal dimension to four, the value given by the usual Porod law. It is shown that the number of particles of which the fractal is composed can be estimated from the value of the boundary between the fractal and Porod regions. The radius of gyration of the fractal is calculated analytically.Comment: 8 pages, 4 figures, accepted for publication in J. Appl. Crys

Characterisation of chitin in the cuticle of a velvet worm (Onychophora)

*Kaya, Murat ( Aksaray, Yazar ) *Baran, Talat ( Aksaray, Yazar )We characterize the trunk cuticle of velvet worms of the Peripatoides novaezealandiae-group (Onychophora) using SEM, TEM, Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). TEM and SEM revealed a relatively uniform organization of the delicate cuticle that is covered by numerous bristled and nonbristled papillae with ribbed scales arranged in transverse rows. The cuticle consists of a very thin multilayered epicuticle of varying appearance followed by the largely fibrous procuticle. The irregularly arranged nanofibres of isolated cuticular chitin seen by SEM are considered as bundles of chitin fibres. FT-IR and TGA showed that the chitin is of the α-type. This confirms and broadens the single previous study in which the presence of α-chitin in a velvet worm was demonstrated with a single analysis (X-ray diffraction)...

Differences in Hypercholesterolemia and Atherogenesis Induced by Common Androgen Deprivation Therapies in Male Mice

Background-Treatment of prostate cancer often involves androgen deprivation therapy (ADT) by gonadotropin-releasing hormone (GnRH) receptor agonists, GnRH receptor antagonists, or orchiectomy. ADT may increase the rate of cardiovascular disease events, but recent clinical studies suggested that not all means of ADT carry the same risk, raising the possibility of non-testosterone-mediated effects of different forms of ADT on atherosclerosis. Here we compared effects of ADT on atherosclerosis in intact and orchiectomized Apoe-deficient mice. Methods and Results-Chow-fed Apoe-deficient mice were allocated to orchiectomy and/or monthly injections with the GnRH receptor agonist leuprolide or the GnRH receptor antagonist degarelix. Atherosclerosis was quantified at 26 weeks of age in the aortic arch by en face examination and in the aortic root by histology. In intact Apoe-deficient mice, all types of ADT reduced testosterone production to castration levels. Although hypercholesterolemia was accentuated in leuprolide-treated mice, the amount and composition of atherosclerosis was not different between the different types of ADT. In orchiectomized Apoe-deficient mice, leuprolide, but not degarelix, augmented hypercholesterolemia, changed body, thymus, and spleen weights, and increased atherosclerosis in the aortic root. No direct effects of the drugs were detectable on cytokine secretion from murine bone marrow-derived macrophages or on splenocyte proliferation. Conclusions-No differences in the development of atherosclerosis were detected among groups of intact Apoe-deficient mice treated with different types of ADT. A pro-atherogenic, possibly cholesterol-mediated, effect of leuprolide was seen in orchiectomized mice that might be relevant for understanding the potential cardiovascular risk associated with GnRH agonist-based ADT.The study was investigator-initiated and sponsored by Ferring Pharmaceuticals.S

Effects of Water Stress, Defoliation and Crop Thinning on Vitis vinifera L. cv. Solaris: Part I: Plant Responses, Fruit Development and Fruit Quality

Viticultural practices and irrigation have a major impact on fruit development and yield, and ultimately on must quality. The effects of water deficit (WD), defoliation (Def), and crop-thinning (CT) on Solaris plants and fruit development, as well as on the chemical composition of grape juice were investigated. WD was induced at three periods during fruit development (pre-veraison, veraison, and ripening) in pot-grown plants, while Def and CT were carried out on field-grown plants. Environmental and vegetative parameters were monitored during the experiments. The bulk chemical composition of the fruits was determined in juice by Fourier Transform-Infrared (FT-IR) spectroscopy throughout fruit ripening and at final harvest. The results showed that WD reduced soil water content and leaf water status. CT significantly reduced yield per vine, but increased cluster size. Mid to late WD reduced soluble solids by 1%. CT increased sugar content in juice, while Def decreased sugar accumulation. Total acids were higher in the juice from the field vines. Yet, CT lowered malic and tartaric acids. Def increased tartaric acid. Ammonia and alpha amino nitrogen were higher in the juice from pot-grown vines, while pH was lowered by Def and raised by CT. It is concluded that Solaris has a remarkable ability to tolerate and recover from WD. CT and Def significantly affected the bulk chemical composition of grapes in terms of total acidity and sugar accumulation, with CT grapes having the highest sugar content and the lowest total acidity and Def the oppositeinfo:eu-repo/semantics/publishedVersio