Exact sampling of self-avoiding paths via discrete Schramm-Loewner evolution

We present an algorithm, based on the iteration of conformal maps, that produces independent samples of self-avoiding paths in the plane. It is a discrete process approximating radial Schramm-Loewner evolution growing to infinity. We focus on the problem of reproducing the parametrization corresponding to that of lattice models, namely self-avoiding walks on the lattice, and we propose a strategy that gives rise to discrete paths where consecutive points lie an approximately constant distance apart from each other. This new method allows us to tackle two non-trivial features of self-avoiding walks that critically depend on the parametrization: the asphericity of a portion of chain and the correction-to-scaling exponent.Comment: 18 pages, 4 figures. Some sections rewritten (including title and abstract), numerical results added, references added. Accepted for publication in J. Stat. Phy

Microhabitat use by the white-clawed crayfish in a Tuscan stream.

Habitat modification, pollution, overfishing, poaching, competition from nonindigenous species, and diseases have led to the extinction in Europe of many populations of indigenous crayfish. Under the rationale that any programme of reintroduction should be preceded by a thorough understanding of habitat requirements of the species of concern, we studied the microhabitat use of an Austropotamobius pallipes population in Tuscany, central Italy. Microhabitat use was assessed for water depth, current velocity, substrate, percentages of boulders, underwater tree roots, and in-stream vegetation cover. Results show that A. pallipes’ habitat use is size-partitioned. Smaller individuals mostly occupy stream edges in shallow waters with submerged roots, whereas larger individuals use deeper waters, often associated with boulders. Crayfish spatial distribution is restricted mostly to the microhabitats characterised by extensive cover and slow current velocity. The study highlights the importance of habitat heterogeneity and cover elements for the protection of this indigenous species

Reply to comment by S. Peacock on “Glacial-interglacial circulation changes inferred from 231Pa/230Th sedimentary record in the North Atlantic region”

Peacock [2010, P10 hereafter] takes issue with several aspects of our recent article [Gherardi et al., 2009, G09hereafter]: (1) our description of the modern Atlantic meridional overturning circulation (AMOC), (2) apparent inconsistencies between modern circulation and our Holo-cene sedimentary 231Pa/230Th bathymetric profile, and (3) our use of cores for reconstructing AMOC from locations that do not lie beneath the Deep Western Boundary Current (DWBC). We welcome the comment as it affords us the opportunity to clarify important aspects of our approach to studying paleocirculation and to address any potential mis-understandings arising from the wording of our original text

Highly transparent poly(2-ethyl-2-oxazoline)-TiO2 nanocomposite coatings for the conservation of matte painted artworks

A nanocomposite coating based on TiO2 nanoparticles and poly(2-ethyl-2-oxazoline) is used as consolidant of matte painted surfaces (temperas, watercolors, modern paintings). The aim of this work is to provide advances in the conservation of these works of art, while preserving their optical appearance, in terms of colour and gloss. Fiber Optic Reflectance Spectroscopy (FORS) measurements of a painting-model (an acrylic black monochrome) treated with the nanocomposite coatings revealed that it is possible to match the optical appearance of the painted surface by tuning the amount of nanoparticles in the polymeric matrix. The requirement of retreatability of the material has been verified by removing the nanocomposite cast on the painted surface with aqueous solutions. FTIR and SEM/EDX measurements showed that almost no traces of the nanocomposite remained on the painted surface, allowing its use for the treatment of real paintings. Test were performed using a contemporary studio-model on canvas attributed to Agostino Bonalumi (1935–2013)

Understanding Interorganizational Learning Based on Social Spaces and Learning Episodes

Different organizational settings have been gaining ground in the world economy, resulting in a proliferation of different forms of strategic alliances that translate into a growth in the number of organizations that have started to deal with interorganizational relationships with different actors. These circumstances reinforce Crossan, Lane, White and Djurfeldt (1995) and Crossan, Mauer and White (2011) in exploring what authors refer to as the fourth, interorganizational, level of learning. These authors, amongst others, suggest that the process of interorganizational learning (IOL) warrants investigation, as its scope of analysis needs widening and deepening. Therefore, this theoretical essay is an attempt to understand IOL as a dynamic process found in interorganizational cooperative relationships that can take place in different structured and unstructured social spaces and that can generate learning episodes. According to this view, IOL is understood as part of an organizational learning continuum and is analyzed within the framework of practical rationality in an approach that is less cognitive and more social-behavioral

Habitat use by the endangered white-clawed crayfish Austropotamobius species complex: a systematic review

Understanding habitat requirements is a key part of conserving declining species, particularly when reintroductions are planned as part of the recovery strategy. The white-clawed crayfish (Austropotamobius pallipes) has undergone severe declines across its range and is now classified by the International Union for Conservation of Nature (IUCN) as ‘endangered’. Translocation of threatened A. pallipes populations to isolated ‘Ark sites’ where threats are minimised is an increasingly used conservation tool. A full feasibility assessment of potential Ark sites, including an assessment of habitat suitability, is recommended within translocation guidelines developed by the IUCN. This literature review employed a systematic search and ‘vote counting’ approach to identify and assess the relative importance of physical habitat requirements of A. pallipes. Many habitat features were positively associated with crayfish presence, in particular: boulder substrate, trees/shading, woody debris, exposed roots, and undercut banks; and habitat use patterns varied among crayfish sexes and size classes. Ark sites should incorporate heterogeneous habitat, with as many of these features as possible, to provide both ample refugia and rich foraging areas

Characterization and structural determination of a new anti-MET function-blocking antibody with binding epitope distinct from the ligand binding domain

The growth and motility factor Hepatocyte Growth Factor/Scatter Factor (HGF/SF) and its receptor, the product of the MET proto-oncogene, promote invasion and metastasis of tumor cells and have been considered potential targets for cancer therapy. We generated a new Met-blocking antibody which binds outside the ligand-binding site, and determined the crystal structure of the Fab in complex with its target, which identifies the binding site as the Met Ig1 domain. The antibody, 107_A07, inhibited HGF/SF-induced cell migration and proliferation in vitro and inhibited growth of tumor xenografts in vivo. In biochemical assays, 107_A07 competes with both HGF/SF and its truncated splice variant NK1 for MET binding, despite the location of the antibody epitope on a domain (Ig1) not reported to bind NK1 or HGF/SF. Overlay of the Fab-MET crystal structure with the InternalinB-MET crystal structure shows that the 107_A07 Fab comes into close proximity with the HGF/SF-binding SEMA domain when MET is in the “compact”, InternalinB-bound conformation, but not when MET is in the “open” conformation. These findings provide further support for the importance of the “compact” conformation of the MET extracellular domain, and the relevance of this conformation to HGF/SF binding and signaling

Fluid geochemistry of the Los Humeros geothermal field (LHGF - Puebla, Mexico): New constraints for the conceptual model

Geothermal power in Mexico is mainly produced in four geothermal fields operated by the Comision Federal de Electricidad (CFE): Cerro Prieto, Los Azufres, Los Humeros, and Las Tres Virgenes. The Los Humeros Geothermal Field (LHGF) is ranked third in terms of generated capacity, and in the last decade its installed capacity has doubled (up to 95.0 MW). Further increases in the geothermal power generation capacity in Mexico are planned, and thus the LHGF warrants further examination. The development and growth phases of any geothermal project must start from an awareness of the conceptual model of the natural system studied. The recharge mechanism, feeding zones, and fluid flow-path must be identified, along with the estimation of the temperature at the productive level and of phase separation (liquid - steam). To accomplish this, detailed fluid geochemical surveys were carried out in June 2017 and March 2018, in which 57 and 87 samples were collected, respectively, from cold and thermal springs, water wells and maar lakes located around and inside the LHGF. Samples from fumaroles inside the producing area were also collected for the first time, together with fluid from re-injection wells. The presence of a meteoric component, which plays an important role at the regional scale, is confirmed by the chemical and isotope data, and its contribution in terms of recharge may be higher than previously assumed. The Sierra Madre Oriental, on the west side of the LHGF, is characterized by widespread outcrops of limestone belonging to the same geological formation as those at the bottom of the LHGF. The isotope composition (delta D and delta O-18, respectively -77.3 parts per thousand and -10.50 parts per thousand for the hypothetical Infiltration Water IW) is similar to that observed in cold springs located in the Sierra Madre Oriental, and from this the evolution of isotopes in the liquid-rock-steam system during water-rock interaction and phase separation processes can be modelled. Thus, the experimental data obtained for natural gas emissions (fumarolic condensates) and for geothermal fluids can be reproduced. These findings suggest that geothermal fluids in the LHGF are likely to be derived from meteoric water infiltrating (IW) the limestone outcrops of the Sierra Madre Oriental. During their flow-path, the infiltrating waters exchange isotopes at a high temperature with the crustal rocks, which have a much higher O-18/O-16 ratio, resulting in a shift towards higher delta O-18 (-4.35 parts per thousand +/- 1) as the water O exchanges with rock O. The vapor phase can be separated from this deep water (DW) and it is discharged from the fumarolic effluents of Loma Blanca. Single Step Vapor Separation (SSVS) and Continuous Steam Separation processes (CSS) were modelled using stable isotopes of water. The results of geochemical modeling agree with available data for geothermal liquids discharged from several geothermal wells, suggesting that steam separation may be interpreted either as SSVS or CSS. Other processes can affect the chemistry and isotope composition of geothermal fluids (e.g. phase segregation, gas exchange, contributions from magmatic-volcanic deep fluids and re-injection fluids). The proposed conceptual model is consistent with both the geochemical data and the geological setting, and provides a useful point of reference for examining the fluid flow-path and geochemical processes active in the LHGF, at least at a general level. An involvement of magmatic-volcanic deep fluids in the feeding mechanism of the geothermal system cannot be excluded at priori, but the regional meteoric end-member is supported by the data and it seems the most important component

Redefining innovation processes: The digital designers at work

As design in digital innovation has become a thing, we highlight the inconclusive concepts that describe design activity in innovation processes. Proposing an alternative theoretical lens - a sociomaterial practice lens - we claim that this view can reveal the contribution of digital designers to the work of innovation. This paper draws on a research study with digital designers in the UK. At the same time as we begin to reconceptualise the ways digital design activity can be described, we also illustrate a theoretical framework based on 1) action and knowing as ordered by collectively produced objects, 2) sociomateriality and the configuration of human bodies and materials in action, 3) the co-emergence of objects and sociomaterial configurations where each is the condition of the other. This alternative way of looking at design activity may pose some challenges to the theoretical traditions in the field. We however believe that it contains immense potential too