1,750 research outputs found
Fish-based groups for ecological assessment in rivers: the importance of environmental drivers on taxonomic and functional traits of fish Assemblages
The use of river-types is of practical value, serving as groups for which
assessment procedures can be developed and applied. An abiotic typology
was set by the Portuguese Water Agency, mainly based on 6 major
morphoclimatic regions. However, to be biologically meaningful, this typology
should fit the distribution patterns of the biological quality elements
communities proposed in Water Framework Directive under the lowest
possible human pressure. This study aimed to identify and characterize
fish-based geographical groups for continental Portugal and their environmental
and geographical discriptors, using taxonomic and functional
traits. Sampling took place between 2004 and 2006 during Spring. Fish
fauna from 155 reference sites was analysed using a multivariate
approach. Cluster Analysis on fish composition identified 10 fish-groups,
expressing a clear correspondence to the river basin level, due to the
restrict basin distribution of many species. Groups showed a wider aggregation
in 4 regions with a larger geographical correspondence, statistically
supported by Similarity Analysis, both on fish composition and mostly on
fish metrics/guilds. Principal Components Analysis revealed major environmental
drivers associated to fish-groups and fish-regions. Fish-groups
were hierarchically grouped over major and local regions, expressing a
large-scale response to a North-South environmental gradient defined by
temperature, precipitation, mineralization and altitude, and a regional scale
response mainly to drainage area and flow discharge. From North to
South, fish-regions were related to the morphoclimatic regions. Results
contributed to reduce redundance in abiotic river-types and set the final
typology for Portuguese rivers, constituting a fundamental tool for planning
and managing water resources
A new approach to dealing with missing values in data-driven fuzzy modeling
Real word data sets often contain many missing elements. Most algorithms that automatically develop a rule-based model are not well suited to deal with incomplete data. The usual technique is to disregard the missing values or substitute them by a best guess estimate, which can bias the results. In this paper we propose a new method for estimating the parameters of a Takagi-Sugeno fuzzy model in the presence of incomplete data. We also propose an inference mechanism that can deal with the incomplete data. The presented method has the added advantage that it does not require imputation or iterative guess-estimate of the missing values. This methodology is applied to fuzzy modeling of a classification and regression problem. The performance of the obtained models are comparable with the results obtained when using a complete data set
FAdo and GUItar: tools for automata manipulation and visualization
Abstract. FAdo is an ongoing project which aims to provide a set of tools for symbolic manipulation of formal languages. To allow highlevel programming with complex data structures, easy prototyping of algorithms, and portability (to use in computer grid systems for example), are its main features. Our main motivation is the theoretical and experimental research, but we have also in mind the construction of a pedagogical tool for teaching automata theory and formal languages. For the graphical visualization and interactive manipulation a new interface application, GUItar, is being developed. In this paper, we describe the main components of the FAdo system as well as the basics of the graphical interface and editor, the export/import filters and its generic interface with external systems, such as FAdo.
Infrared behaviour of the pressure in g\phi^3 theory in 6 dimensions
In an earlier paper Almeida and Frenkel considered the calculation of the
pressure in g\phi^3 theory in 6 dimensions via the Schwinger--Dyson equation.
They found, under certain approximations, that a finite result ensues in the
infrared limit. We find this conclusion to remain true with certain variations
of these approximations, suggesting the finiteness of the result to be fairly
robust.Comment: 6 pages, 4 figures, uses revtex
Unfolding the dynamical structure of Lisbon’s public space: space syntax and micromobility data
Space Syntax and the theory of natural movement demonstrated that spatial mor- phology is a primary factor influencing movement. This paper investigates to what extent spatial morphology at different scales (node, community and global network) influences the use of public space by micromobility. An axial map and corresponding network for Lisbon’s walkable and open public space, and data from e-scooters parking locations, is used as case study. Relevant metrics and their correlations (intelligibility, accessibility, permeability and local dimension) for the quantitative characterization
of spatial morphology properties are described and computed for Lisbon’s axial map. Communities are identified based on the network topological structure in order to investigate how these properties are affected at different scales in the case study. The resulting axial line clustering is compared via the variation of information metric with the clustering obtained from e-scooters’ proximity. The results obtained enable to con- clude that the space syntax properties are scale dependent in Lisbon’s pedestrian net- work. On the other hand both the correlation between these properties, the number of scooters and the variation of information between clusters indicate that the spatial morphology is not the only factor influencing micromobility. Through the compara- tive analysis between the main properties of the public space network of Lisbon and data collected from e-scooters locations in a timeframe, centrality becomes a dynamic concept, relying not only on the static topological properties of the urban network, but also on other quantitative and qualitative factors, since the flows’ operating on the network will operate several transformations on the spatial network properties through time, uncovering spatiotemporal dynamics.info:eu-repo/semantics/publishedVersio
Comparative genomics suggests primary homothallism of Pneumocystis species.
UNLABELLED: Pneumocystis species are fungal parasites of mammal lungs showing host specificity. Pneumocystis jirovecii colonizes humans and causes severe pneumonia in immunosuppressed individuals. In the absence of in vitro cultures, the life cycle of these fungi remains poorly known. Sexual reproduction probably occurs, but the system of this process and the mating type (MAT) genes involved are not characterized. In the present study, we used comparative genomics to investigate the issue in P. jirovecii and Pneumocystis carinii, the species infecting rats, as well as in their relative Taphrina deformans. We searched sex-related genes using 103 sequences from the relative Schizosaccharomyces pombe as queries. Genes homologous to several sex-related role categories were identified in all species investigated, further supporting sexuality in these organisms. Extensive in silico searches identified only three putative MAT genes in each species investigated (matMc, matMi, and matPi). In P. jirovecii, these genes clustered on the same contig, proving their contiguity in the genome. This organization seems compatible neither with heterothallism, because two different MAT loci on separate DNA molecules would have been detected, nor with secondary homothallism, because the latter involves generally more MAT genes. Consistently, we did not detect cis-acting sequences for mating type switching in secondary homothallism, and PCR revealed identical MAT genes in P. jirovecii isolates from six patients. A strong synteny of the genomic region surrounding the putative MAT genes exists between the two Pneumocystis species. Our results suggest the hypothesis that primary homothallism is the system of reproduction of Pneumocystis species and T. deformans.
IMPORTANCE: Sexual reproduction among fungi can involve a single partner (homothallism) or two compatible partners (heterothallism). We investigated the issue in three pathogenic fungal relatives: Pneumocystis jirovecii, which causes severe pneumonia in immunocompromised humans; Pneumocystis carinii, which infects rats; and the plant pathogen Taphrina deformans. The nature, the number, and the organization within the genome of the genes involved in sexual reproduction were determined. The three species appeared to harbor a single genomic region gathering only three genes involved in sexual differentiation, an organization which is compatible with sexual reproduction involving a single partner. These findings illuminate the strategy adopted by fungal pathogens to infect their hosts
Improvement of the guiding performances of near infrared organic/inorganic channel waveguides
New sol-gel derived organic/inorganic hybrid single mode waveguides devices
have been developed for telecommunication applications in the two near infrared
windows at 1310 and 1550 nm. The overall procedure of fabrication of these
devices is described and the refractive indices of the guiding, the buffer and
the protective layers are adjusted by a precise control of the materials'
composition. Due to the improvement of the composition of the guiding layer,
the attenuation losses are significantly decreased to 0.8 dB/cm and 2dB/cm at
respectively 1310 and 1550 nm
Community mediators in South Sudan: empirical legitimacy and post-conflict rule of law building
The scholarship on legitimacy of dispute settlement institutions has largely ignored community mediation institutions operating in the global south. This article aims to remedy that gap, through a case study of community mediation groups in South Sudan, a state emerging from large-scale conflict where formal courts are only marginally able to fulfill their assigned roles and the rule of law needs to be built almost from the ground-up. The article studies both the empirical legitimacy of the community mediation groups and how they relate to the rule of law building project in the country. Is the empirical legitimacy of formal and informal dispute settlement institutions as a zero-sum relationship, where increasing popularity and use of informal dispute settlement institutions detract from the popularity and empirical legitimacy of formal institutions, inhibiting the maturation of the legal system and a rule of law? Or could informal dispute settlement institutions – with proper linkages to the formal system – strengthen formal institutions, both judicial and administrative? These are highly relevant questions for post-conflict states where building a well-functioning legal system is seen as a precondition for sustainable peace and development.Effective Protection of Fundamental Rights in a pluralist worl
Doença Pulmonar Obstrutiva Crónica em Portugal: estudo Pneumobil (1995) e estudo de prevalência de 2002 revisitados
ResumoIntroduçãoA doença pulmonar obstrutiva crónica (DPOC) tem sido, ao longo dos anos, uma importante causa de morbilidade e mortalidade no mundo. Em 1995, a implementação de um rastreio da função respiratória pareceu a forma mais adequada para alertar para os sintomas respiratórios negligenciados e sensibilizar para os rastreios espirométricos. Em 2002, foram criadas novas normas consensuais de diagnóstico e o reconhecimento de que a prevalência da DPOC depende dos critérios de definição de obstrução das vias aéreas. O objetivo deste estudo foi revisitar estes 2 estudos e publicar alguns dos resultados e respetivas metodologias.MétodosDos 12 684 indivíduos que constavam da base de dados do Pneumobil, apenas os indivíduos com 40 e mais anos (n = 9061) foram considerados para esta análise. No estudo de 2002 foi incluída uma amostra aleatorizada e representativa de 1384 indivíduos, com idades entre os 35 e os 69 anos.ResultadosA prevalência da DPOC foi de 8,96% no estudo Pneumobil e de 5,34% no estudo de 2002. Em ambos os estudos, a presença da DPOC foi superior no sexo masculino, tendo-se verificado uma associação positiva entre a presença da DPOC e os grupos etários mais velhos. Nos fumadores e ex-fumadores encontrou-se maior proporção de casos com DPOC.ConclusõesA prevalência em Portugal é mais baixa do que noutros países europeus, o que pode estar relacionado com uma menor prevalência de tabagismo. De um modo geral, os fatores de risco mais importantes que mostraram a associação com a DPOC foram a idade maior do que 60 anos, o sexo masculino e a exposição tabágica. Todos os aspetos e as limitações que se referem a diferentes critérios de definição e a metodologias de recrutamento realçam a necessidade de métodos padronizados para determinar a prevalência da DPOC e os fatores de risco associados, cujos resultados possam ser comparados entre países, como acontece no projeto BOLD.AbstractBackgroundChronic Obstructive Pulmonary Disease (COPD) has been a leading cause of morbidity and mortality worldwide, over the years. In 1995, the implementation of a respiratory function survey seemed to be an adequate way to draw attention to neglected respiratory symptoms and increase the awareness of spirometry surveys. By 2002 there were new consensual guidelines in place and the awareness that prevalence of COPD depended on the criteria used for airway obstruction definition. The purpose of this study is to revisit the two studies and to turn public some of the data and respective methodologies.MethodsFrom Pneumobil study database of 12,684 subjects, only the individuals with 40+ years old (n = 9.061) were selected. The 2002 study included a randomized representative sample of 1,384 individuals with 35-69 years old.ResultsThe prevalence of COPD was 8.96% in Pneumobil and 5.34% in the 2002 study. In both studies, presence of COPD was greater in males and there was a positive association between presence of COPD and older age groups. Smokers and ex-smokers showed a higher proportion of cases of COPD.ConclusionsPrevalence in Portugal is lower than in other European countries. This may be related to lower smokers’ prevalence. Globally, the most important risk factors associated with COPD were age over 60 years, male gender and smoking exposure. All aspects and limitations regarding different recruitment methodologies and different criteria for defining COPD cases highlight the need of a standardized method to evaluate COPD prevalence and associated risks factors, whose results can be compared across countries, as it is the case of BOLD project
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