The origin of power-law distributions in deterministic walks: the influence of landscape geometry

We investigate the properties of a deterministic walk, whose locomotion rule is always to travel to the nearest site. Initially the sites are randomly distributed in a closed rectangular ($A/L \times L)$ landscape and, once reached, they become unavailable for future visits. As expected, the walker step lengths present characteristic scales in one ($L \to 0$) and two ($A/L \sim L$) dimensions. However, we find scale invariance for an intermediate geometry, when the landscape is a thin strip-like region. This result is induced geometrically by a dynamical trapping mechanism, leading to a power law distribution for the step lengths. The relevance of our findings in broader contexts -- of both deterministic and random walks -- is also briefly discussed.Comment: 7 pages, 11 figures. To appear in Phys. Rev.

Proteomics Reveals mRNA Regulation and the Action of Annexins in Thyroid Cancer

Differentiated thyroid cancer is the most common malignancy of the endocrine system. Although most thyroid nodules are benign, given the high incidence of thyroid nodules in the population, it is important to understand the differences between benign and malignant thyroid cancer and the molecular alterations associated with malignancy to improve detection and signal potential diagnostic, prognostic, and therapeutic targets. Proteomics analysis of benign and malignant human thyroid tissue largely revealed changes indicating modifications in RNA regulation, a common cancer characteristic. In addition, changes in the immune system and cell membrane/endocytic processes were also suggested to be involved. Annexin A1 was considered a potential malignancy biomarker and, similarly to other annexins, it was found to increase in the malignant group. Furthermore, a bioinformatics approach points to the transcription factor Sp1 as being potentially involved in most of the alterations seen in the malignant thyroid nodules

Comparação entre protocolos para extração de DNA de cupuaçu (Theobroma grandiflorum).

O cupuaçu é uma espécie nativa na região Amazônica que se encontra em estágio inicial de domesticação, apresentando ampla variabilidade genética para as diversas características. Contudo, poucos são os estudos que envolvem avaliações moleculares nesta espécie. A otimização de um protocolo para extração de DNA é pré-requisito básico para etapas subseqüentes da análise molecular. Com o objetivo realizar amplificação e melhoria da qualidade e quantidade de DNA obtido dessa espécie, o presente trabalho compara protocolos de extração de DNA do cupuaçu. Os protocolos utilizados foram o de Doyle e Doyle (1990), modificado por FIGUEIRA et al. (1997) com a utilização de proteinase K, e o Doyle e Doyle (1990), modificado por FERREIRA GRA TTAP AGLIA (1998) estabelecido para várias espécies e já utilizado no setor de Biologia Molecular do Laboratório de Morfogênese e Biologia Molecular da EMBRAPA-Acre, em ambos os protocolos também foram feitos os testes com beads de cerâmica e de tungstênio. Os resultados obtidos na quantificação das amostras mostraram que o emprego da proteinase K produziu um DNA mais limpo. Porém, quando se compara esta metodologia com a que não utilizou a proteinase K, verificou-se uma menor quantidade de DNA extraído. A utilização das beads de cerâmica proporcionou um aumento significativo na quantidade de DNA, no entanto, não se obteve boa qualidade, apresentando DNA fragmentado. Em meio a esses resultados pode-se constatar que o uso das beads de tungstênio e sem o emprego da proteinase K possibilitaram a extração de um DNA com melhor qualidade e quantidade. Cupuassu is a native species in the Amazon region that finds in initial stage of domesticated, that has ample genetic variability for the diverse characteristics. However, few studies that involve molecular evaluations in this species. The optimization of a protocol of DNA extraction is basic prerequisite for subsequent steps the molecular analysis. With the objective J of realization the amplification and improvement of the quality and amount in DNA of this species, the present work compares two protocols of DNA extraction. The protocols of extraction ofDNA that utilized were Doyle and Doyle (1990), modified for FIGUEIRA et al. (1997) with the use of proteinase K, and the Doyle and Doyle (1990), modified for FERRERIA and GRA TTAP AGLIA (1998) established for some species and used in the sector of Molecular Biology in the Laboratory of Morphogenesis and Molecular Biology of EMBRAPA-Acre, in both of protocols also were made the tests with ceramics and tungsten beads. The results obtained in quantification of samples had shown that the used of proteinase K produced a cleaner DNA. However, when this methodology is compared with that did not use proteinase K, was verified a few amount of extracted DNA. The use of beads of ceramics provided a significant increase in the DNA amount, however, did not get good quality, shown DNA fragmented. These results evidenced that the use of tungsten beads and no utilization of proteinase K makes possible the better quality and amount in DNA extration

Equilibrium random-field Ising critical scattering in the antiferromagnet Fe(0.93)Zn(0.07)F2

It has long been believed that equilibrium random-field Ising model (RFIM) critical scattering studies are not feasible in dilute antiferromagnets close to and below Tc(H) because of severe non-equilibrium effects. The high magnetic concentration Ising antiferromagnet Fe(0.93)Zn(0.07)F2, however, does provide equilibrium behavior. We have employed scaling techniques to extract the universal equilibrium scattering line shape, critical exponents nu = 0.87 +- 0.07 and eta = 0.20 +- 0.05, and amplitude ratios of this RFIM system.Comment: 4 pages, 1 figure, minor revision

Caveolin-1 and -2 in airway epithelium: expression and in situ association as detected by FRET-CLSM

BACKGROUND: Caveolae are involved in diverse cellular functions such as signal transduction, cholesterol homeostasis, endo- and transcytosis, and also may serve as entry sites for microorganisms. Hence, their occurrence in epithelium of the airways might be expected but, nonetheless, has not yet been examined. METHODS: Western blotting, real-time quantitative PCR analysis of abraded tracheal epithelium and laser-assisted microdissection combined with subsequent mRNA analysis were used to examine the expression of cav-1 and cav-2, two major caveolar coat proteins, in rat tracheal epithelium. Fluorescence immunohistochemistry was performed to locate caveolae and cav-1 and -2 in the airway epithelium of rats, mice and humans. Electron-microscopic analysis was used for the identification of caveolae. CLSM-FRET analysis determined the interaction of cav-1α and cav-2 in situ. RESULTS: Western blotting and laser-assisted microdissection identified protein and transcripts, respectively, of cav-1 and cav-2 in airway epithelium. Real-time quantitative RT-PCR analysis of abraded tracheal epithelium revealed a higher expression of cav-2 than of cav-1. Immunoreactivities for cav-1 and for cav-2 were co-localized in the cell membrane of the basal cells and basolaterally in the ciliated epithelial cells of large airways of rat and human. However, no labeling for cav-1 or cav-2 was observed in the epithelial cells of small bronchi. Using conventional double-labeling indirect immunofluorescence combined with CLSM-FRET analysis, we detected an association of cav-1α and -2 in epithelial cells. The presence of caveolae was confirmed by electron microscopy. In contrast to human and rat, cav-1-immunoreactivity and caveolae were confined to basal cells in mice. Epithelial caveolae were absent in cav-1-deficient mice, implicating a requirement of this caveolar protein in epithelial caveolae formation. CONCLUSION: These results show that caveolae and caveolins are integral membrane components in basal and ciliated epithelial cells, indicating a crucial role in these cell types. In addition to their physiological role, they may be involved in airway infection

Passives and Se Constructions

In this chapter we discuss some of the main properties of constructions involving participial passives, passive se, and impersonal se in Portuguese, focusing on its two main varieties, European and Brazilian Portuguese (henceforth EP and BP, respectively).1 When the two dialects differ, we will provide the relevant judgments each dialect assigns to the data under discussion by using the abbreviations EP and BP. The chapter is organized in five sections. Section 2 deals with participial passives, distinguishing between adjectival and verbal passives and between the participial forms of passives and compound tenses. Section 3 focuses on passive se and impersonal se constructions, comparing them with verbal passives when appropriate. Section 4 concludes the paper.info:eu-repo/semantics/publishedVersio

Local mean-field study of capillary condensation in silica aerogels

We apply local mean-field (i.e. density functional) theory to a lattice model of a fluid in contact with a dilute, disordered gel network. The gel structure is described by a diffusion-limited cluster aggregation model. We focus on the influence of porosity on both the hysteretic and the equilibrium behavior of the fluid as one varies the chemical potential at low temperature. We show that the shape of the hysteresis loop changes from smooth to rectangular as the porosity increases and that this change is associated to disorder-induced out-of-equilibrium phase transitions that differ on adsorption and on desorption. Our results provide insight in the behavior of $^4$He in silica aerogels.Comment: 19 figure

Towards a standardization of biomethane potential tests

8 PáginasProduction of biogas from different organic materials is a most interesting source of renewable energy. The biomethane potential (BMP) of these materials has to be determined to get insight in design parameters for anaerobic digesters. A workshop was held in June 2015 in Leysin Switzerland to agree on common solutions to the conundrum of inconsistent BMP test results. A discussion covers actions and criteria that are considered compulsory ito accept and validate a BMP test result; and recommendations concerning the inoculum substrate test setup and data analysis and reporting ito obtain test results that can be validated and reproduced.The workshop in Leysin, Switzerland, has been financed by the Swiss Federal Office for Energy, and co-sponsored by Bioprocess Control Sweden AB, Lund, Sweden. The authors thank Alexandra Maria Murray for editing the English