The impact of structured teaching methods on the quality of education in Brazil

This paper estimates the impact of the use of structured methods on the quality of education for students in primary public school in Brazil. Structured methods encompass a range of pedagogical and managerial instruments applied in the educational system. In recent years, several municipalities in the state of Sao Paulo have contracted out private educational providers to implement these structured methods in their schooling systems. Their pedagogical proposal involves structuring of curriculum content, development of teacher and student textbooks, and the training and supervision of teachers anti instructors. Using a difference-in-differences estimation strategy, we find that the 4th- and 8th-grade students in the municipalities with structured methods performed better in Portuguese and mathematics than did students in municipalities not exposed to these methods. We find no differences in passing rates. A robustness test supports the assumption that there is no unobserved municipal characteristics associated with proficiency changes over time that may affect the results. (C) 2012 Elsevier Ltd. All rights reserved.

Extractive summarization using complex networks and syntactic dependency

The realization that statistical physics methods can be applied to analyze written texts represented as complex networks has led to several developments in natural language processing, including automatic summarization and evaluation of machine translation. Most importantly, so far only a few metrics of complex networks have been used and therefore there is ample opportunity to enhance the statistics-based methods as new measures of network topology and dynamics are created. In this paper, we employ for the first time the metrics betweenness, vulnerability and diversity to analyze written texts in Brazilian Portuguese. Using strategies based on diversity metrics, a better performance in automatic summarization is achieved in comparison to previous work employing complex networks. With an optimized method the Rouge score (an automatic evaluation method used in summarization) was 0.5089, which is the best value ever achieved for an extractive summarizer with statistical methods based on complex networks for Brazilian Portuguese. Furthermore, the diversity metric can detect keywords with high precision, which is why we believe it is suitable to produce good summaries. It is also shown that incorporating linguistic knowledge through a syntactic parser does enhance the performance of the automatic summarizers, as expected, but the increase in the Rouge score is only minor. These results reinforce the suitability of complex network methods for improving automatic summarizers in particular, and treating text in general. (C) 2011 Elsevier B.V. All rights reserved.

HIV-1 Proviral DNA Loads (as Determined by Quantitative PCR) in Patients Subjected to Structured Treatment Interruption after Antiretroviral Therapy Failure

The impact of Structured Treatment Interruption (STI) in peripheral blood mononuclear cell (PBMC) proviral reservoirs in 41 highly active antiretroviral therapy (HAART)-treated viremic individuals at baseline and 12 weeks after STI was determined using quantitative PCR (qPCR). Viral load increased 0.7 log(10) and CD4 decreased 97.5 cells/mm(3) after 12 weeks. A total of 28 of the 41 individuals showed an increased proviral load, 19 with a statistically significant increase above 10%. An increase in active viral replication is an important factor in the replenishment of the proviral reservoir even for short time periods.

Complex Transition to Cooperative Behavior in a Structured Population Model

Cooperation plays an important role in the evolution of species and human societies. The understanding of the emergence and persistence of cooperation in those systems is a fascinating and fundamental question. Many mechanisms were extensively studied and proposed as supporting cooperation. The current work addresses the role of migration for the maintenance of cooperation in structured populations. This problem is investigated in an evolutionary perspective through the prisoner's dilemma game paradigm. It is found that migration and structure play an essential role in the evolution of the cooperative behavior. The possible outcomes of the model are extinction of the entire population, dominance of the cooperative strategy and coexistence between cooperators and defectors. The coexistence phase is obtained in the range of large migration rates. It is also verified the existence of a critical level of structuring beyond that cooperation is always likely. In resume, we conclude that the increase in the number of demes as well as in the migration rate favor the fixation of the cooperative behavior.

Incorporating label dependency into the binary relevance framework for multi-label classification

In multi-label classification, examples can be associated with multiple labels simultaneously. The task of learning from multi-label data can be addressed by methods that transform the multi-label classification problem into several single-label classification problems. The binary relevance approach is one of these methods, where the multi-label learning task is decomposed into several independent binary classification problems, one for each label in the set of labels, and the final labels for each example are determined by aggregating the predictions from all binary classifiers. However, this approach fails to consider any dependency among the labels. Aiming to accurately predict label combinations, in this paper we propose a simple approach that enables the binary classifiers to discover existing label dependency by themselves. An experimental study using decision trees, a kernel method as well as Naive Bayes as base-learning techniques shows the potential of the proposed approach to improve the multi-label classification performance.

A stochastic spatially structured epidemic model with diffusive processes

We developed a stochastic lattice model to describe the vector-borne disease (like yellow fever or dengue). The model is spatially structured and its dynamical rules take into account the diffusion of vectors. We consider a bipartite lattice, forming a sub-lattice of human and another occupied by mosquitoes. At each site of lattice we associate a stochastic variable that describes the occupation and the health state of a single individual (mosquito or human). The process of disease transmission in the human population follows a similar dynamic of the Susceptible-Infected-Recovered model (SIR), while the disease transmission in the mosquito population has an analogous dynamic of the Susceptible-Infected-Susceptible model (SIS) with mosquitos diffusion. The occurrence of an epidemic is directly related to the conditional probability of occurrence of infected mosquitoes (human) in the presence of susceptible human (mosquitoes) on neighborhood. The probability of diffusion of mosquitoes can facilitate the formation of pairs Susceptible-Infected enabling an increase in the size of the epidemic. Using an asynchronous dynamic update, we study the disease transmission in a population initially formed by susceptible individuals due to the introduction of a single mosquito (human) infected. We find that this model exhibits a continuous phase transition related to the existence or non-existence of an epidemic. By means of mean field approximations and Monte Carlo simulations we investigate the epidemic threshold and the phase diagram in terms of the diffusion probability and the infection probability.

Portfolio: Objective structured examination for the assessment of essential competences at graduation

[EN] This porfolio is an Objective Structured Competence Examination (OSCE) designed for the Assessment of essentian competences defined by The European Asociation of Establishments for Veterinay Education (EAEVE) in its programme Evaluation of Veterinary Training in Europe

A model and an algebra for semi-structured and full-text queries

The need for a convergence between semi-structured data management and Information Retrieval techniques is manifest to the scientific community. In order to fulfil this growing request, W3C has recently proposed XQuery Full Text, an IR-oriented extension of XQuery. However, the issue of query optimization requires the study of important properties like query equivalence and containment; to this aim, a formal representation of document and queries is needed. The goal of this thesis is to establish such formal background. We define a data model for XML documents and propose an algebra able to represent most of XQuery Full-Text expressions. We show how an XQuery Full-Text expression can be translated into an algebraic expression and how an algebraic expression can be optimized.

Kernel Methods for Tree Structured Data

Machine learning comprises a series of techniques for automatic extraction of meaningful information from large collections of noisy data. In many real world applications, data is naturally represented in structured form. Since traditional methods in machine learning deal with vectorial information, they require an a priori form of preprocessing. Among all the learning techniques for dealing with structured data, kernel methods are recognized to have a strong theoretical background and to be effective approaches. They do not require an explicit vectorial representation of the data in terms of features, but rely on a measure of similarity between any pair of objects of a domain, the kernel function. Designing fast and good kernel functions is a challenging problem. In the case of tree structured data two issues become relevant: kernel for trees should not be sparse and should be fast to compute. The sparsity problem arises when, given a dataset and a kernel function, most structures of the dataset are completely dissimilar to one another. In those cases the classifier has too few information for making correct predictions on unseen data. In fact, it tends to produce a discriminating function behaving as the nearest neighbour rule. Sparsity is likely to arise for some standard tree kernel functions, such as the subtree and subset tree kernel, when they are applied to datasets with node labels belonging to a large domain. A second drawback of using tree kernels is the time complexity required both in learning and classification phases. Such a complexity can sometimes prevents the kernel application in scenarios involving large amount of data. This thesis proposes three contributions for resolving the above issues of kernel for trees. A first contribution aims at creating kernel functions which adapt to the statistical properties of the dataset, thus reducing its sparsity with respect to traditional tree kernel functions. Specifically, we propose to encode the input trees by an algorithm able to project the data onto a lower dimensional space with the property that similar structures are mapped similarly. By building kernel functions on the lower dimensional representation, we are able to perform inexact matchings between different inputs in the original space. A second contribution is the proposal of a novel kernel function based on the convolution kernel framework. Convolution kernel measures the similarity of two objects in terms of the similarities of their subparts. Most convolution kernels are based on counting the number of shared substructures, partially discarding information about their position in the original structure. The kernel function we propose is, instead, especially focused on this aspect. A third contribution is devoted at reducing the computational burden related to the calculation of a kernel function between a tree and a forest of trees, which is a typical operation in the classification phase and, for some algorithms, also in the learning phase. We propose a general methodology applicable to convolution kernels. Moreover, we show an instantiation of our technique when kernels such as the subtree and subset tree kernels are employed. In those cases, Direct Acyclic Graphs can be used to compactly represent shared substructures in different trees, thus reducing the computational burden and storage requirements.

Self assembled monolayers for engineering of structured inorganic materials in the micrometer and submicrometer range

Deutsch:In der vorliegenden Arbeit konnten neue Methoden zur Synthese anorganischer Materialien mit neuartiger Architektur im Mikrometer und Nanometer Maßstab beschrieben werden. Die zentrale Rolle der Formgebung basiert dabei auf der templatinduzierten Abscheidung der anorganischen Materialien auf selbstorganisierten Monoschichten. Als Substrate eignen sich goldbedampfte Glasträger und Goldkolloide, die eine Mittelstellung in der Welt der Atome bzw. Moleküle und der makroskopischen Welt der ausgedehnten Festkörper einnehmen. Auf diesen Substraten lassen sich Thiole zu einer monomolekularen Schicht adsorbieren und damit die Oberflächeneigenschaften des Substrates ändern. Ein besonderer Schwerpunkt bei dieser Arbeit stellt die Synthese speziell auf die Bedürfnisse der jeweiligen Anwendung ausgerichteten Thiole dar.Im ersten Teil der Arbeit wurden goldbedampfte Glasoberflächen als Template verwendet. Die Abscheidung von Calciumcarbonat wurde in Abhängigkeit der Schichtdicke der adsorbierten Monolage untersucht. Aragonit, eine der drei Hauptphasen des Calciumcarbonat Systems, wurde auf polyaromatischen Amid - Oberflächen mit Schichtdicken von 5 - 400 nm Dicke unter milden Bedingung abgeschieden. Die einstellbaren Parameter waren dabei die Kettenlänge des Polymers, der w-Substituent, die Bindung an die Goldoberfläche über Verwendung verschiedener Aminothiole und die Kristallisationstemperatur. Die Schichtdickeneinstellung der Polymerfilme erfolgte hierbei über einen automatisierten Synthesezyklus.Titanoxid Filme konnten auf Oberflächen strukturiert werden. Dabei kam ein speziell synthetisiertes Thiol zum Einsatz, das die Funktionalität einer Styroleinheit an der Oberflächen Grenze als auch eine Möglichkeit zur späteren Entfernung von der Oberfläche in sich vereinte. Die PDMS Stempeltechnik erzeugte dabei Mikrostrukturen auf der Goldoberfläche im Bereich von 5 bis 10 µm, die ihrerseits über die Polymerisation und Abscheidung des Polymers in den Titanoxid Film überführt werden konnten. Drei dimensionale Strukturen wurden über Goldkolloid Template erhalten. Tetraethylenglykol konnte mit einer Thiolgruppe im Austausch zu einer Hydroxylgruppe monofunktionalisiert werden. Das erhaltene Molekül wurde auf kolloidalem Gold selbstorganisiert; es entstand dabei ein wasserlösliches Goldkolloid. Die Darstellung erfolgte dabei in einer Einphasenreaktion. Die so erhaltenen Goldkolloide wurden als Krstallisationstemplate für die drei dimensionale Abscheidung von Calciumcarbonat verwendet. Es zeigte sich, dass Glykol die Kristallisation bzw. den Habitus des krsitalls bei niedrigem pH Wert modifiziert. Bei erhöhtem pH Wert (pH = 12) jedoch agieren die Glykol belegten Goldkolloide als Template und führen zu sphärisch Aggregaten. Werden Goldkolloide langkettigen Dithiolen ausgesetzt, so führt dies zu einer Aggregation und Ausfällung der Kolloide aufgrund der Vernetzung mehrer Goldkolloide mit den Thiolgruppen der Alkyldithiole. Zur Vermeidung konnte in dieser Arbeit ein halbseitig geschütztes Dithiol synthetisiert werden, mit dessen Hilfe die Aggregation unterbunden werden konnte. Das nachfolgende Entschützten der Thiolfunktion führte zu Goldkolloiden, deren Oberfläche Thiol funktionalisiert werden konnte. Die thiolaktiven Goldkolloide fungierten als template für die Abscheidung von Bleisulfid aus organisch/wässriger Lösung. Die Funktionsweise der Schutzgruppe und die Entschützung konnte mittels Plasmonenresonanz Spektroskopie verdeutlicht werden. Titanoxid / Gold / Polystyrol Komposite in Röhrenform konnten synthetisiert werden. Dazu wurde ein menschliches Haar als biologisches Templat für die Formgebung gewählt.. Durch Bedampfung des Haares mit Gold, Assemblierung eines Stryrolmonomers, welches zusätzlich eine Thiolfunktionalität trug, Polymerisation auf der Oberfläche, Abscheidung des Titanoxid Films und anschließendem Auflösen des biologischen Templates konnte eine Röhrenstruktur im Mikrometer Bereich dargestellt werden. Goldkolloide fungierten in dieser Arbeit nicht nur als Kristallisationstemplate und Formgeber, auch sie selbst wurden dahingehend modifiziert, dass sie drahtförmige Agglormerate im Nanometerbereich ausbilden. Dazu wurden Template aus Siliziumdioxid benutzt. Zum einen konnten Nanoröhren aus amorphen SiO2 in einer Sol Gel Methode dargestellt werden, zum anderen bediente sich diese Arbeit biologischer Siliziumoxid Hohlnadeln aus marinen Schwämmen isoliert. Goldkolloide wurden in die Hohlstrukturen eingebettet und die Struktur durch Ausbildung von Kolloid - Thiol Netzwerken mittels Dithiol Zugabe gefestigt. Die Gold-Nanodrähte im Bereich von 100 bis 500 nm wurden durch Auflösen des SiO2 - Templates freigelegt.

Structured P2P Video Streaming and Collaborative Failure Detection

Il video streaming in peer-to-peer sta diventando sempre più popolare e utiliz- zato. Per tali applicazioni i criteri di misurazione delle performance sono: - startup delay: il tempo che intercorre tra la connessione e l’inizio della ripro- duzione dello stream (chiamato anche switching delay), - playback delay: il tempo che intercorre tra l’invio da parte della sorgente e la riproduzione dello stream da parte di un peer, - time lag: la differenza tra i playback delay di due diversi peer. Tuttavia, al giorno d’oggi i sistemi P2P per il video streaming sono interessati da considerevoli ritardi, sia nella fase di startup che in quella di riproduzione. Un recente studio su un famoso sistema P2P per lo streaming, ha mostrato che solitamente i ritardi variano tra i 10 e i 60 secondi. Gli autori hanno osservato anche che in alcuni casi i ritardi superano i 4 minuti! Si tratta quindi di gravi inconvenienti se si vuole assistere a eventi in diretta o se si vuole fruire di applicazioni interattive. Alcuni studi hanno mostrato che questi ritardi sono la conseguenza della natura non strutturata di molti sistemi P2P. Ogni stream viene suddiviso in blocchi che vengono scambiati tra i peer. A causa della diffusione non strutturata del contenuto, i peer devono continuamente scambiare informazioni con i loro vicini prima di poter inoltrare i blocchi ricevuti. Queste soluzioni sono estremamente re- sistenti ai cambiamenti della rete, ma comportano una perdita notevole in termini di prestazioni, rendendo complicato raggiungere l’obiettivo di un broadcast in realtime. In questo progetto abbiamo lavorato su un sistema P2P strutturato per il video streaming che ha mostrato di poter offrire ottimi risultati con ritardi molto vicini a quelli ottimali. In un sistema P2P strutturato ogni peer conosce esattamente quale blocchi inviare e a quali peer. Siccome il numero di peer che compongono il sistema potrebbe essere elevato, ogni peer dovrebbe operare possedendo solo una conoscenza limitata dello stato del sistema. Inoltre il sistema è in grado di gestire arrivi e partenze, anche raggruppati, richiedendo una riorganizzazione limitata della struttura. Infine, in questo progetto abbiamo progettato e implementato una soluzione personalizzata per rilevare e sostituire i peer non più in grado di cooperare. Anche per questo aspetto, l’obiettivo è stato quello di minimizzare il numero di informazioni scambiate tra peer.

Electrosynthesis and characterization of structured catalysts

In this research work the optimization of the electrochemical system of LDHs as catalytic precursors on FeCrAlY foams was carried out. Preliminary sintheses were performed on flat surfaces in order to easily characterize the deposited material. From the study of pH evolution vs time at different cathodic potentials applied to a Pt electrode, the theoretical best working conditions for the synthesis of single hydroxides and LDH compounds was achieved. In order to define the optimal potential for the synthesis of a particular LDH compound, the collected data were compared with the interval of precipitation determined by titration with NaOH. However, the characterization of the deposited material on Pt surfaces did not confirm the deposition of a pure and homogeneous LDH phase during the synthesis. Instead a sequential deposition linked to the pH of precipitation of the involved elements is observed. The same behavior was observed during the synthesis of the RhMgAl LDH on FeCrAlY foam as catalytic precursor. Several parameters were considered in order to optimize the synthesis.. The development of electrochemical cells with different feature, such as the counter electrode dimensions or the contact between the foam and the potentiostat, had been carried out in order to obtain a better coating of the foam. The influence of the initial pH of the electrolyte solution, of the applied potential, of the composition of the electrolytic solution were investigated in order to improve a better coating of the catalyst support. Catalytic tests were performed after the calcination of the deposited foam for the CPO and SR reactions, showing an improve of performances along with optimization of the precursors synthesis conditions.

Development of newly conceived biomimetic nano-structured biomaterials as scaffolds for bone and osteochondral regeneration

The present research thesis was focused on the development of new biomaterials and devices for application in regenerative medicine, particularly in the repair/regeneration of bone and osteochondral regions affected by degenerative diseases such as Osteoarthritis and Osteoporosis or serious traumas. More specifically, the work was focused on the synthesis and physico-chemical-morphological characterization of: i) a new superparamagnetic apatite phase; ii) new biomimetic superparamagnetic bone and osteochondral scaffolds; iii) new bioactive bone cements for regenerative vertebroplasty. The new bio-devices were designed to exhibit high biomimicry with hard human tissues and with functionality promoting faster tissue repair and improved texturing. In particular, recent trends in tissue regeneration indicate magnetism as a new tool to stimulate cells towards tissue formation and organization; in this perspective a new superparamagnetic apatite was synthesized by doping apatite lattice with di-and trivalent iron ions during synthesis. This finding was the pin to synthesize newly conceived superparamagnetic bone and osteochondral scaffolds by reproducing in laboratory the biological processes yielding the formation of new bone, i.e. the self-assembly/organization of collagen fibrils and heterogeneous nucleation of nanosized, ionically substituted apatite mimicking the mineral part of bone. The new scaffolds can be magnetically switched on/off and function as workstations guiding fast tissue regeneration by minimally invasive and more efficient approaches. Moreover, in the view of specific treatments for patients affected by osteoporosis or traumas involving vertebrae weakening or fracture, the present work was also dedicated to the development of new self-setting injectable pastes based on strontium-substituted calcium phosphates, able to harden in vivo and transform into strontium-substituted hydroxyapatite. The addition of strontium may provide an anti-osteoporotic effect, aiding to restore the physiologic bone turnover. The ceramic-based paste was also added with bio-polymers, able to be progressively resorbed thus creating additional porosity in the cement body that favour cell colonization and osseointegration.

Hyperverzweigte Lacton-Copolymere: enzymatische Synthese, Charakterisierung und Darstellung strukturierter Polymernetzwerke = (Hyperbranched lactone copolymers by enzyme catalysis: synthesis, characterization and preparation of structured polymer networks)

Hyperverzweigte Polymere erfuhren in den letzten Jahren immer mehr Beachtung, da sie im Vergleich zu ihren linearen Analoga besondere Eigenschaften besitzen. Im Jahre 2002 wurde die erste enzymkatalysierte Darstellung hyperverzweigter Poly(epsilon-caprolacton)e (hb-PCL) beschrieben. Hier ermöglichte das Konzept der konkurrierenden ringöffnenden Polymerisation und Polykondensation die Kontrolle der Eigenschaften des dargestellten Polymers. Detaillierte Untersuchungen in Hinblick auf Grenzen und Möglichkeiten, aber auch die Synthese im Technikumsmaßstab sind wesentliche Aspekte dieser Arbeit. Außerdem wird ein neues Konzept eingeführt, das Reknitting genannt wurde. Ziel desselben ist das Recycling kommerziellen, linearen PCLs mittels Umesterung zu hb-PCL durch Enzymkatalyse. Diese hb-PCLs zeigen vergleichbare Eigenschaften zu den aus den Comonomeren dargestellten. Ausgehend von hb-PCL sollte eine geeignete Route zu methacrylierten Vernetzerverbindungen entwickelt werden. Aus Mischungen derselben mit 2-Hydroxyethylmethacrylat wurden komplexe Netzwerkarchitekturen durch Copolymerisation erhalten. Diese Netzwerke wurden in Hinblick auf ihre mechanisch physikalischen Eigenschaften untersucht. Zuletzt wurden Screeningexperimente an anderen zyklischen Estern durchgeführt, da ein Transfer des oben vorgestellten Konzepts angestrebt wurde. Zwei neue hyperverzweigte Polymerklassen, hb-Poly(delta-valerolacton) und hb-Polytrimethylencarbonat wurden detaillierter untersucht und in Ihren Eigenschaften mit hb-PCL verglichen.