String order and adiabatic continuity of Haldane chains and band insulators

The ground state of spin-1 Haldane chains is characterized by the so-called string order. We show that the same hidden order is also present in ordinary one-dimensional band insulators. We construct a family of Hamiltonians which connects adiabatically band insulators to two topologically non-equivalent spin models, the Haldane chain and the antiferromagnetic spin-1/2 ladder. We observe that the localized spin-1/2 edge-state characteristic of spin-1 chains is smoothly connected to a surface-bound state of band insulators and its emergence is not related to any bulk phase transition. Furthermore, we show that the string order is absent in any dimensions higher than one.Comment: 6 pages, 7 figures. Appendix about charge string orders added. Version as publishe

Fragility of String Orders

One-dimensional gapped systems are often characterized by a 'hidden' non-local order parameter, the so-called string order. Due to the gap, thermodynamic properties are robust against a weak higher-dimensional coupling between such chains or ladders. To the contrary, we find that the string order is not stable and decays for arbitrary weak inter-chain or inter-ladder coupling. We investigate the vanishing of the order for three different systems: spin-one Haldane chains, band insulators, and the transverse-field Ising model. Using perturbation theory and bosonization, we show that the fragility of the string order arises from non-local commutation relations between the non-local order parameter and the perturbation.Comment: 7 pages, 3 figures. Published versio

Morphometric characteristics and internal structures of intertidal bars on the northwest Cadiz littoral (southwestern Iberian Peninsula)

The present paper deals with morphometric bar characteristics, to discriminate between bars that are associated with dissipative beaches and reflective ones. We shall focus on the former: their internal structures and migration rate. The beaches studied are located between the cities of Chipiona and Rota (southwest Iberian Peninsula). Dissipative beaches have a gentle slope (2 %) and are 120 m wide; moderately reflective beaches have a 5 % slope and are 90 m wide. We found that bars associated with reflective beaches are larger than those associated with dissipative beaches. On the reflective beaches, bars are convex upwards, with a seaward slope of 9° and a landward slope of 5°. On the dissipative beaches, bars have a wide, smooth crest, a seaward slope of 2°-3°, and a landward slope of 1°-2°. They are generally composed of thin sets of plane bedding laminae, parallel to the beach surface.Este trabajo pretende una descripción morfométrica de las barras intermareales para distinguir entre las asociadas a perfiles disipativos y las asociadas a perfiles reflectivos, profundizando más en las primeras en cuanto a estructuras internas y migración. El litoral estudiado se sitúa entre las ciudades de Chipiona y Rota (suroeste de la península Ibérica). Las playas disipativas presentan pendiente muy suave (2 %) y anchura de aproximadamente 120 m; las reflectivas tienen pendiente media del 5 % y anchura en torno a 90 m. Se ha encontrado que las barras asociadas a perfiles reflectivos son de mayores dimensiones que las asociadas a perfiles disipativos. Aquéllas son convexas y tienen una elevada pendiente en su lado hacia el mar (9°) y una pendiente menor en el lado hacia tierra. Las últimas presentan una amplia y aplanada cresta, el lado hacia el mar tiene una pendiente de 2°-3° y el lado hacia tierra de 1°-2°. Sus estructuras internas están constituidas por láminas paralelas a la superficie.Instituto Español de Oceanografí

Low-energy local density of states of the 1D Hubbard model

We examine the local density of states (DOS) at low energies numerically and analytically for the Hubbard model in one dimension. The eigenstates represent separate spin and charge excitations with a remarkably rich structure of the local DOS in space and energy. The results predict signatures of strongly correlated excitations in the tunneling probability along finite quantum wires, such as carbon nanotubes, atomic chains or semiconductor wires in scanning tunneling spectroscopy (STS) experiments. However, the detailed signatures can only be partly explained by standard Luttinger liquid theory. In particular, we find that the effective boundary exponent can be negative in finite wires, which leads to an increase of the local DOS near the edges in contrast to the established behavior in the thermodynamic limit.Comment: 6 pages, 4 figures, more information can be found at http://www.physik.uni-kl.de/eggert/papers/index.htm

Assessing and managing scenery of the Caribbean Coast of Colombia

This study provides the coastal scenery assessment of 135 sites along the Colombian Caribbean littoral by analysing 26 physical and human factors. Sites were categorised into five classes from Class 1, top grade scenery, to Class 5, poor scenery. Fifty five percent of the investigated coastal areas were included in Classes 1 and 2, 18% belonged to Class 3 and 47% of the sites fall into Classes 4 and 5. Classification of analysed sites depends on the geological setting and the degree of human occupation. Classes 1 and 2 sites are located in natural protected areas in La Guajira and Magdalena departments. Low classification recorded at Classes 3, 4 and 5 corresponds to a progressive decrease of both natural and (especially) human parameters. Concerning coastal management issues, emphasis should be given to the upgrading of human parameters eliminating litter and sewage evidences, vegetation debris and enhancing beach nourishment work

Coastal scenic beauty and sensitivity at the balearic islands, spain: Implication of natural and human factors

Coastal areas globally are facing a significant range of environmental stresses, enhanced by climate change-related processes and a continuous increase of human activities. The economic benefits of tourism are well-known for coastal regions, but, very often, conflicts arise between short-term benefits and long-term conservation goals. Among beach user preferences, five parameters of greater importance stand out from the rest, i.e., safety, facilities, water quality, litter and scenery; the latter is the main concern of this study. A coastal scenic evaluation was carried out in the Balearic Islands and focused on two major issues: coastal scenic beauty together with sensitivity to natural processes and human pressure. The archipelago is renowned as a top international coastal tourist destination that receives more than 13.5 million visitors (2019). Impressive landscape diversity makes the Balearics Islands an ideal field for this research. In total, 52 sites, respectively located in Ibiza (11), Formentera (5), Mallorca (18) and Menorca (18), were field-tested. In a first step, coastal scenic beauty was quantified using the coastal scenic evaluation system (CSES) method, based on the evaluation of 26 physical and human parameters, and using weighting matrices parameters and fuzzy logic mathematics. An evaluation index (“D”) was obtained for each site, allowing one to classify them in one of the five scenic classes established by the method. Twenty-nine sites were included in class I, corresponding to extremely attractive sites (CSES), which were mainly observed in Menorca. Several sound measures were proposed to maintain and/or enhance sites’ scenic value. In a second step, scenic sensitivity was evaluated using a novel methodological approach that makes possible the assessment of three different coastal scenic sensitivity indexes (CSSI), i.e., the natural sensitivity index NSI, the human sensitivity index HSI and the total sensitivity index TSI. Future climate change trends and projection of tourism development, studied at municipality scale, were considered as correction factors. All the islands showed places highly sensitive to environmental processes, while sensitivity to human pressure was essentially observed at Ibiza and Mallorca. Thereafter, sites were categorized into one of three sensitive groups established by the methodology. Results obtained are useful in pointing out very sensitive sceneries as well as limiting, preventing and/or anticipating future scenic degradation linked to natural and human issues

Diverging thermal expansion of the spin-ladder system (C5_5H12_{12}N)2_2CuBr4_4

We present high-resolution measurements of the $c^\star$-axis thermal expansion and magnetostriction of piperidinium copper bromide \hp. The experimental data at low temperatures is well accounted for by a two-leg spin-ladder Hamiltonian. The thermal expansion shows a complex behaviour with various sign changes and approaches a $1/\sqrt{T}$ divergence at the critical fields. All low-temperature features are semi-quantitatively explained within a free fermion model; full quantitative agreement is obtained with Quantum Monte Carlo simulations.Comment: 4 pages, 5 figures; version 2 is slightly shortened and typos are correcte

Evaluation of the scenic value of 100 beaches in Cuba: Implications for coastal tourism management

This paper provides coastal scenic values of 100 sites along coastal Cuba by the use of a weighted, fuzzy logic, based checklist containing 26 physical/human factors. Sites were categorized into five classes from Class I, top grade scenery, to Class V, poor scenery. Seven beaches belonged to Class I, e.g. rural areas with a low impact of human activities and high scores of natural parameters. Most Class II beaches were located at international resort areas in cays having white coral sand beaches, turquoise water and vigorous vegetation together with a low impact of tourist developments because of appropriate location and design. Classes III, IV and V presented a wide distribution and their lower scores were linked to a poor environmental setting. Results allow for improvements to beach management plans to be formulated for current international tourist destinations (in cays) and other potentially attractive coastal areas at new developing tourist destinations

A tunable nanoplatform of nanogold functionalised with Angiogenin peptides for anti-angiogenic therapy of brain tumours

Angiogenin (ANG), an endogenous protein that plays a key role in cell growth and survival, has been scrutinised here as promising nanomedicine tool for the modulation of pro-/anti-angiogenic processes in brain cancer therapy. Specifically, peptide fragments from the putative cell membrane binding domain (residues 60-68) of the protein were used in this study to obtain peptide-functionalised spherical gold nanoparticles (AuNPs) of about 10 nm and 30 nm in optical and hydrodynamic size, respectively. Different hybrid biointerfaces were fabricated by peptide physical adsorption (Ang60-68) or chemisorption (the cysteine analogous Ang60-68Cys) at the metal nanoparticle surface, and cellular assays were performed in the comparison with ANG-functionalised AuNPs. Cellular treatments were performed both in basal and in copper-supplemented cell culture medium, to scrutinise the synergic effect of the metal, which is another known angiogenic factor. Two brain cell lines were investigated in parallel, namely tumour glioblastoma (A172) and neuron-like differentiated neuroblastoma (d-SH-SY5Y). Results on cell viability/proliferation, cytoskeleton actin, angiogenin translocation and vascular endothelial growth factor (VEGF) release pointed to the promising potentialities of the developed systems as anti-angiogenic tunable nanoplaftforms in cancer cells treatment

Morphological cells in the Ragusa littoral (Sicily, Italy)

Geomorphologic information, topographic maps (dated 1967), aerial photographs (dated 1999 and 2008), and spatial analysis procedures were used to investigate a 90 km long coastal sector in South Sicily (Italy). Information was obtained on coastal erosion/accretion areas, general sediment circulation pattern and littoral cell distribution. Human-made structures and natural headlands constituted important artificial limits dividing littoral in morphological cells. Ports and harbours were observed at Scoglitti, Punta Secca, Marina di Ragusa, Donnalucata and Pozzallo. Most of them worked as “transit” limits which interrupted predominant, eastward directed sedimentary transport, this way generating accretion in updrift (west) side of mentioned structures and erosion in downdrift (east) side. During the 1967–2008 period, about 62,000 m2 and 42,000 m2 of beach surface were respectively formed updrift of Scoglitti and Donnalucata ports. The construction of Pozzallo port gave rise to the formation of a “convergent” limit which favoured large accretion (94,000 m2) east of port structure. Most important natural structures were observed at Punta Zafaglione, P. Braccetto and Cava d’Aliga. The knowledge of littoral cell distribution acquires a great importance for appropriate management of coastal erosion processes which may be mitigated installing by-passing systems in ports and harbours and carrying out nourishment works in eroding areas, often located downdrift of ports and harbours (when these structures work as transit limits) and in central part of littoral cells (when these structures work as convergent limits)