Sudden emergence of q-regular subgraphs in random graphs

We investigate the computationally hard problem whether a random graph of finite average vertex degree has an extensively large $q$-regular subgraph, i.e., a subgraph with all vertices having degree equal to $q$. We reformulate this problem as a constraint-satisfaction problem, and solve it using the cavity method of statistical physics at zero temperature. For $q=3$, we find that the first large $q$-regular subgraphs appear discontinuously at an average vertex degree c_\reg{3} \simeq 3.3546 and contain immediately about 24% of all vertices in the graph. This transition is extremely close to (but different from) the well-known 3-core percolation point c_\cor{3} \simeq 3.3509. For $q>3$, the $q$-regular subgraph percolation threshold is found to coincide with that of the $q$-core.Comment: 7 pages, 5 figure

Unbalanced Langmuir kinetics affects TASEP dynamical transitions: mean-field theory

In a previous study we developed a mean-field theory of dynamical transitions for the totally-asymmetric simple-exclusion process (TASEP) with open boundaries and Langmuir kinetics, in the so-called balanced regime, characterized by equal binding and unbinding rates. Here we show that simply including the possibility of unbalanced rates gives rise to an unexpectedly richer dynamical phase diagram. In particular, the current work predicts an unusual type of dynamical transition, which exhibits certain similarities with first-order phase transitions of equilibrium systems. We also point out that different types of dynamical transition are accompanied by different structural changes in the (mean-field) relaxation spectrum.Comment: 32 pages, 8 figure

Hydration of an apolar solute in a two-dimensional waterlike lattice fluid

In a previous work, we investigated a two-dimensional lattice-fluid model, displaying some waterlike thermodynamic anomalies. The model, defined on a triangular lattice, is now extended to aqueous solutions with apolar species. Water molecules are of the "Mercedes Benz" type, i.e., they possess a D3 (equilateral triangle) symmetry, with three equivalent bonding arms. Bond formation depends both on orientation and local density. The insertion of inert molecules displays typical signatures of hydrophobic hydration: large positive transfer free energy, large negative transfer entropy (at low temperature), strong temperature dependence of the transfer enthalpy and entropy, i.e., large (positive) transfer heat capacity. Model properties are derived by a generalized first order approximation on a triangle cluster.Comment: 9 pages, 5 figures, 1 table; submitted to Phys. Rev.

INTEROPERABILIDADE Bim e Bem: Avaliação de Eficiência do Sistema na Análise Energética de Edifícios

A crescente demanda energética impõe quebra de paradigmas no que diz respeito às questões das fontes geradoras e os meios de tornar a sua utilização mais sustentável. A indústria da construção civil possui o papel importante, considerando que o consumo energético do setor é bastante significativo em todo o ciclo de vida de uma edificação, no entanto, uma série de ferramentas tem surgido com intuito de tornar o setor de Arquitetura, Engenharia e Construção AEC, mais eficiente e com menor impacto ambiental, sendo o Building Information Modeling BIM e os programas de modelagem energética da edificação (BEM Building Energy Modeling) integrantes deste grupo. A pesquisa avaliou o desempenho da interoperabilidade entre as ferramentas do BIM e BEM após o compartilhamento dos modelos Referência e Ajustado, e os seus parâmetros calculados pelo Método Prescritivo do RTQ-C. Os modelos criados da edificação padrão tiveram as suas envoltórias detalhadas na ferramenta do BIM da Autodesk®, o Revit® Architecture e compartilhados com as ferramentas BEM Green Building Studio; EnergyPlus; eQUEST; DesignBuilder; IES-VE; OpenStudio e Insight por meio de dois formatos padrões de interoperabilidade, IFC e gbXML, e os derivados do gbXML IDF e INP. Três ferramentas não realizaram as simulações após a interoperabilidade, sejam importando arquivos gbXML e IFC ou carregando os arquivos IDF e INP. Entre as ferramentas que realizaram as simulações, somente o EnergyPlus apresentou resultado coerente e consistente após carregar os arquivos IDF derivados do gbXML da ferramenta Green Building Studio e do plugin Insight. Palavras-chave: Interoperabilidade, BIM, BEM, IFC, gbXML, eficiência energética

A discrete model of water with two distinct glassy phases

We investigate a minimal model for non-crystalline water, defined on a Husimi lattice. The peculiar random-regular nature of the lattice is meant to account for the formation of a random 4-coordinated hydrogen-bond network. The model turns out to be consistent with most thermodynamic anomalies observed in liquid and supercooled-liquid water. Furthermore, the model exhibits two glassy phases with different densities, which can coexist at a first-order transition. The onset of a complex free-energy landscape, characterized by an exponentially large number of metastable minima, is pointed out by the cavity method, at the level of 1-step replica symmetry breaking.Comment: expanded version: 6 pages, 7 figure

Two-dimensional lattice-fluid model with water-like anomalies

We investigate a lattice-fluid model defined on a two-dimensional triangular lattice, with the aim of reproducing qualitatively some anomalous properties of water. Model molecules are of the "Mercedes Benz" type, i.e., they possess a D3 (equilateral triangle) symmetry, with three bonding arms. Bond formation depends both on orientation and local density. We work out phase diagrams, response functions, and stability limits for the liquid phase, making use of a generalized first order approximation on a triangle cluster, whose accuracy is verified, in some cases, by Monte Carlo simulations. The phase diagram displays one ordered (solid) phase which is less dense than the liquid one. At fixed pressure the liquid phase response functions show the typical anomalous behavior observed in liquid water, while, in the supercooled region, a reentrant spinodal is observed.Comment: 9 pages, 1 table, 7 figure

Investigation of mechanisms underlying chaotic genetic patchiness in the intertidal marbled crab Pachygrapsus marmoratus (Brachyura: Grapsidae) across the Ligurian Sea

Abstract Background Studies on marine community dynamics and population structures are limited by the lack of exhaustive knowledge on the larval dispersal component of connectivity. Genetic data represents a powerful tool in understanding such processes in the marine realm. When dealing with dispersion and connectivity in marine ecosystems, many evidences show patterns of genetic structure that cannot be explained by any clear geographic trend and may show temporal instability. This scenario is usually referred to as chaotic genetic patchiness, whose driving mechanisms are recognized to be selection, temporal shifts in local population dynamics, sweepstakes reproductive success and collective dispersal. In this study we focused on the marbled crab Pachygrapsus marmoratus that inhabits the rocky shores of the Mediterranean Sea, Black Sea and East Atlantic Ocean, and disperses through planktonic larvae for about 1 month. P. marmoratus exhibits unexpectedly low connectivity levels at local scale, although well-defined phylogeographic patterns across the species’ distribution range were described. This has been explained as an effect of subtle geographic barriers or due to sweepstake reproductive success. In order to verify a chaotic genetic patchiness scenario, and to explore mechanisms underlying it, we planned our investigation within the Ligurian Sea, an isolated basin of the western Mediterranean Sea, and we genotyped 321 individuals at 11 microsatellite loci. Results We recorded genetic heterogeneity among our Ligurian Sea samples with the occurrence of genetic clusters not matching the original populations and a slight inter-population divergence, with the geographically most distant populations being the genetically most similar ones. Moreover, individuals from each site were assigned to all the genetic clusters. We also recorded evidences of self-recruitment and a higher than expected within-site kinship. Conclusions Overall, our results suggest that the chaotic genetic patchiness we found in P. marmoratus Ligurian Sea populations is the result of a combination of differences in reproductive success, en masse larval dispersion and local larval retention. This study defines P. marmoratus as an example of marine spawner whose genetic pool is not homogenous at population level, but rather split in a chaotic mosaic of slightly differentiated genetic patches derived from complex and dynamic ecological processes

Looking for Nano- and Microplastics in Meiofauna Using Advanced Methodologies

: Meiofauna (body size within 30–1000 µm) are the community of microscopic invertebrates that live at the bottom of marine and freshwater ecosystems and play a key role in the food webs of these environments. Several studies have addressed the adverse effects of anthropic stressors on meiofauna; however, data on the presence and impact of plastic debris in wild meiofaunal organisms are scant. Since the amount of microplastic waste in sediments may surge rapidly, ascertaining the ingestion of these xenobiotics by the abundant micrometazoan community is necessary to understand their potential accumulation in aquatic food webs and their hazard to the health of the ecosystem. The absence of documentation in this regard may be due to the difficulty in detecting the small size of the plastic fragments meiofauna may potentially ingest. To overcome this difficulty, we developed an integrated approach based on different microscopic/spectroscopic techniques suitable for detecting plastic particles of sizes down to 200 nm.Meiofauna (body size within 30–1000 m) are the community of microscopic invertebrates that live at the bottom of marine and freshwater ecosystems and play a key role in the food webs of these environments. Several studies have addressed the adverse effects of anthropic stressors on meiofauna; however, data on the presence and impact of plastic debris in wild meiofaunal organisms are scant. Since the amount of microplastic waste in sediments may surge rapidly, ascertaining the ingestion of these xenobiotics by the abundant micrometazoan community is necessary to understand their potential accumulation in aquatic food webs and their hazard to the health of the ecosystem. The absence of documentation in this regard may be due to the difficulty in detecting the small size of the plastic fragments meiofauna may potentially ingest. To overcome this difficulty, we developed an integrated approach based on different microscopic/spectroscopic techniques suitable for detecting plastic particles of sizes down to 200 nm

Zinc and other metals deficiencies and risk of type 1 diabetes: an ecological study in the high risk Sardinia island

Type 1 diabetes incidence presents a decreasing gradient in Europe from the Nordic countries to the Mediterranean ones. Exception to this gradient is represented by Sardinia, the second largest Mediterranean island whose population shows the highest incidence in Europe, after Finland. The genetic features of this population have created a fertile ground for the epidemic of the disease, however, as well as being strikingly high, the incidence rate has suddenly presented a continuous increase from the '50s, not explainable by accumulation of new genetic variants. Several environmental factors have been taken into account, possibly interacting with the genetic/epigenetic scenario, but there are no strong evidences to date

approach to a water safety plan for recreational waters disinfection of a drainage pumping station as an unconventional point source of fecal contamination

Abstract In the context of the management of bathing water quality, the intermittent contamination of rainwater drainage pumps (unconventional point sources) could be controlled by peracetic acid disinfection. Thus, a field experimental study was carried out to set up a water safety plan, determining the monitoring parameters and the critical limit for corrective actions. With a 0.5 mg/l dosage, the average logarithmic microbial reduction was 0.50 ± 0.48 for Escherichia coli (EC) and 0.43 ± 0.54 for intestinal enterococci. Among the chemical and physical parameters that could be monitored in real time, the oxidation–reduction potential was the only one able to predict the microbial concentration discharged from a drainage pump and the logarithmic abatement of EC. Considering the possible impact of this source on bathing waters in terms of additional risk of gastrointestinal infections, the critical limit for continuous monitoring was established using a quantitative microbial risk assessment (QMRA) model