Quantum Google in a Complex Network

We investigate the behavior of the recently proposed quantum Google algorithm, or quantum PageRank, in large complex networks. Applying the quantum algorithm to a part of the real World Wide Web, we find that the algorithm is able to univocally reveal the underlying scale-free topology of the network and to clearly identify and order the most relevant nodes (hubs) of the graph according to their importance in the network structure. Moreover, our results show that the quantum PageRank algorithm generically leads to changes in the hierarchy of nodes. In addition, as compared to its classical counterpart, the quantum algorithm is capable to clearly highlight the structure of secondary hubs of the network, and to partially resolve the degeneracy in importance of the low lying part of the list of rankings, which represents a typical shortcoming of the classical PageRank algorithm. Complementary to this study, our analysis shows that the algorithm is able to clearly distinguish scale-free networks from other widespread and important classes of complex networks, such as Erd\H{o}s-R\'enyi networks and hierarchical graphs. We show that the ranking capabilities of the quantum PageRank algorithm are related to an increased stability with respect to a variation of the damping parameter $\alpha$ that appears in the Google algorithm, and to a more clearly pronounced power-law behavior in the distribution of importance among the nodes, as compared to the classical algorithm. Finally, we study to which extent the increased sensitivity of the quantum algorithm persists under coordinated attacks of the most important nodes in scale-free and Erd\H{o}s-R\'enyi random graphs

Deterministic hierarchical networks

It has been shown that many networks associated with complex systems are small-world (they have both a large local clustering coefficient and a small diameter) and they are also scale-free (the degrees are distributed according to a power law). Moreover, these networks are very often hierarchical, as they describe the modularity of the systems that are modeled. Most of the studies for complex networks are based on stochastic methods. However, a deterministic method, with an exact determination of the main relevant parameters of the networks, has proven useful. Indeed, this approach complements and enhances the probabilistic and simulation techniques and, therefore, it provides a better understanding of the systems modeled. In this paper we find the radius, diameter, clustering coefficient and degree distribution of a generic family of deterministic hierarchical small-world scale-free networks that has been considered for modeling real-life complex systems

Recursive graphs with small-world scale-free properties

We discuss a category of graphs, recursive clique trees, which have small-world and scale-free properties and allow a fine tuning of the clustering and the power-law exponent of their discrete degree distribution. We determine relevant characteristics of those graphs: the diameter, degree distribution, and clustering parameter. The graphs have also an interesting recursive property, and generalize recent constructions with fixed degree distributions.Comment: 4 pages, 2 figure

Aflatoxines i ocratoxines: agents tòxics que cal controlar

El present article se centra en l'estudi de toxines produïdes per fongs dels gèneres Aspergillus i Penicillium, més concretament en les aflatoxines B1, G1, B2, G2 i ocratoxina A. Es dóna una visió general del tema quant a origen, legislació, toxicitat i control de micotoxines. A més, es presenten tres mètodes per a l'anàlisi d'aquestes toxines en productes vegetals, ja que són els substrats en els quals es presenten més habitualment. Primerament, es desenvolupa un metòde d'anàlisi per a la determinació d'aflatoxines B1, G1, B2 i G2 en una planta medicinal. Posteriorment, s'optimitza l'anàlisi d'ocratoxina A en cafè i finalment es presenta un mètode per a la determinació simultània d'aflatoxines B1, G1, B2, G2 i ocratoxina A en cervesa. En tots els mètodes s'empra extracció en fase sòlida de reblert polimèric i cromatografia líquida de fase inversa. La detecció es realitza per espectrometria de masses de quadrupol simple amb ionització a pressió atmosfèrica.This paper is focused on the study of mycotoxins produced by fungi of the genera Aspergillus and Penicillium, specifically on aflatoxins B1, G1, B2, G2 and ochratoxin A. A general survey of mycotoxin origin, toxicity, legislation and control is presented. Furthermore, three analytical methods for the analysis of mycotoxins in vegetable products is presented, due to these substrates are the most liable to be contaminated. First, a method for the determination of aflatoxins B1, G1, B2 and G2 in a medicinal herb is presented. Afterwards, the analysis of ochratoxin A in coffee was optimized. Finally, a method for the simultaneous analysis of aflatoxins B1, G1, B2, G2 and ochratoxin A in beer is developed. All the methods apply solid-phase clean-up using a polymeric sorbent and liquid chromatography with a reversed phase column. A single quadruple mass spectrometer with an electrospray ionization source was used as a detector

La transmissió lingüística intergeneracional en espis majoritàriament catalanòfons: el cas d'estudiants al·loglots al Berguedà i les Terres de l'Ebre

Aquest article estudia la transmissió lingüística intergeneracional d'una mostra d'estudiants de secundària i batxillerat de dues zones de Catalunya caracteritzades per una alta presència del català com a llengua inicial i d'ús. Sobre la base d'un qüestionari distribuït entre alumnes d'origen migrant, es compara la llengua que parlen els pares entre si i la llengua que declaren els informants com a inicial per tal de determinar si hi ha indicis de substitució. Així mateix, es compara la llengua inicial declarada amb la llengua d'identificació per tal de detectar possible interrupció de la transmissió.This article examines intergenerational language transmission based on a sample of secondary school students in two areas of Catalonia where, for the vast majority, Catalan is both the first language and the language used. Based on a questionnaire distributed among immigrant students, the language which parents spoke to each other and the language which the students stated to be their first language were compared in order to determine any evidence of substitution. A comparison was also made between the reported first language and the language of (cultural) identification in order to detect whether transmission could come to cease

What Matters Most to Patients and Rheumatologists? A Discrete Choice Experiment in Rheumatoid Arthritis

Introduction: To determine patient and rheumatologist preferences for rheumatoid arthritis (RA) treatment attributes in Spain and to evaluate their attitude towards shared decision-making (SDM). Methods: Observational, descriptive, exploratory and cross-sectional study based on a discrete choice experiment (DCE). To identify the attributes and their levels, a literature review and two focus groups (patients [P] = 5; rheumatologists [R] = 4) were undertaken. Seven attributes with 2–4 levels were presented in eight scenarios. Attribute utility and relative importance (RI) were assessed using a conditional logit model. Patient preferences for SDM were assessed using an ad hoc questionnaire. Results: Ninety rheumatologists [52.2% women; mean years of experience 18.1 (SD: 9.0); seeing an average of 24.4 RA patients/week (SD: 15.3)] and 137 RA patients [mean age: 47.5 years (SD: 10.7); 84.0% women; mean time since diagnosis of RA: 14.2 years (SD: 11.8) and time in treatment: 13.2 years (SD: 11.2), mean HAQ score 1.2 (SD: 0.7)] participated in the study. In terms of RI, rheumatologists and RA patients viewed: time with optimal QoL: R: 23.41%/P: 35.05%; substantial symptom improvement: R: 13.15%/P: 3.62%; time to onset of treatment action: R: 16.24%/P: 13.56%; severe adverse events: R: 10.89%/P: 11.20%; mild adverse events: R: 4.16%/P: 0.91%; mode of administration: R: 25.23%/P: 25.00%; and added cost: R: 6.93%/P: 10.66%. Nearly 73% of RA patients were involved in treatment decision-making to a greater or lesser extent; however, 27.4% did not participate at all. Conclusion: Both for rheumatologists and patients, the top three decision-making drivers are time with optimal quality, treatment mode of administration and time to onset of action, although in different ranking order. Patients were willing to be more involved in the treatment decision-making process

The spectra of Manhattan street networks

AbstractThe multidimensional Manhattan street networks constitute a family of digraphs with many interesting properties, such as vertex symmetry (in fact they are Cayley digraphs), easy routing, Hamiltonicity, and modular structure. From the known structural properties of these digraphs, we determine their spectra, which always contain the spectra of hypercubes. In particular, in the standard (two-dimensional) case it is shown that their line digraph structure imposes the presence of the zero eigenvalue with a large multiplicity

Análisis simultáneo de aflatoxinas y ocratoxina A en compost por HPLC-MS

Las aflatoxinas y ocratoxina A son las micotoxinas más estudiadas debido a su elevada toxicidad y amplia distribución. En este trabajo se describe un método de análisis simultáneo de las aflatoxinas B1, B2, G1, G2 y la ocratoxina A en compost por HPLC-MS. El método consiste en una extracción de las toxinas con MeOH:H 2O, posterior purificación de la muestra con cartuchos de extracción en fase sólida y posterior análisis cromatográfico en 18 minutos utilizando una columna XTerra (2.1x100mm, 3.5mm). En este trabajo se demuestra que no hay presencia de las toxinas de interes a concentraciones superiores a 0,2mg/kg