## NEXT DI-SMALLTALKS SLOTS — 2015

DI-Smalltalks are currently on hold … after about 2^6 presentations.
We might return in 2016!
Meanwhile, feel free to let us know if you would like to give a presentation.

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## Trusted Distributed Processing Over a Large State

When: Thursday, 2015-June-25, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Bruno Vavala

Abstract: Trusted Computing is about guaranteeing the integrity of a remote service based on a small piece of secure hardware. Despite several solutions have been proposed, they either focus on small applications or their performance strongly depends from the service’s state size. In this DI-Smalltalk I will advance some ideas to deal with the problem of computing over a large state in a constrained environment, while still being able to deliver security guarantees that are efficiently verifiable.

About the presenter: Ph.D. student at FCUL-DI & CMU-CSD

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## Brokered ID — a killer app for S2PC?

When: Tuesday, 2015-May-19, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Luís Brandão

Abstract: Secure two-party computation allows two parties to compute functions of their combined inputs, while retaining privacy of the inputs. Progress in recent years has improved up to a practical level the efficiency of this functionality. And now what? In what applications is S2PC going to find its way in the real world? In this DI-Smalltalk I will ask for ideas of practical applications of S2PC and will talk about brokered identification as a candidate context where a small S2PC can be used to solve a big privacy problem.

About the presenter: Ph.D. student at FCUL-DI and CMU-ECE

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## On the Performance of Byzantine Fault-Tolerant MapReduce

When: Wednesday, 2015-May-06, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Pedro Costa

Abstract:
MapReduce is often used for critical data processing, e.g., in the context of scientific or financial simulation. However, there is evidence in the literature that there are arbitrary (or Byzantine) faults that may corrupt the results of MapReduce without being detected.

In this smalltalk I will present an (i) overview of the MapReduce framework, (ii) focus on the limitations of the framework, (iii) describe the existent related work, (iv) show a new design to make the framework able to tolerate arbitrary faults, (iv) present two modes of execution in order to improve performance, (v) and show the results of the experiments.

This is a first step in order to scale out MapReduce computation to a cloud of clouds environment.

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## Computational challenges in Gene Expression studies

When: Thursday, 2015-Apr-02, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Margarida Gama-Carvalho

Abstract: Since Francis Crick introduced his pioneer concepts in the 50’s that molecular biologists like myself have been striving in the lab to unravel the principles and mechanisms underlying biological information. Recently, however, major breakthroughs in technology – namely ‘Next Generation Sequencing’ – have turned biology into a data intensive science, highly reliant on demanding computational approaches.

In this DI-Smalltalk I will provide an overview on these topics and current challenges. By the end, I expect the audience to have gained some insight into this brave new world, full of opportunities to apply their expert knowledge, hopefully paving the way for interdisciplinary collaborations.

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## A Lotaria da Avaliação Docente DI-FCUL

When: Thursday, 2015-Feb-19, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Pedro Veiga

Abstract: Tendo tido responsabilidades na avaliação docente que decorreu em 2013 e aproximando-se novo ciclo (se bem que com nova legislação e regulamentação) tentarei partilhar alguma da experiência que recolhi.

About the presenter: Docente do DI

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## Raft Consensus

When: Thursday, 2015-Feb-12, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Pedro Costa

Abstract: Raft is a consensus algorithm that is designed to be easy to understand. It’s equivalent to Paxos in fault-tolerance and performance. The difference is that it’s decomposed into relatively independent subproblems, and it cleanly addresses all major pieces needed for practical systems. In this talk I will present this algorithm and show the system model.

Slides here

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## Exploring declarative and operational models for communication-centered programming

When: Thursday, 2015-Jan-22, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Hugo A. López

Abstract: Communication-Centred (CC) programming has as a focus the descriptions of reliable communication protocols for distributed systems. Interestingly, there has been two main visions when specifying CC programs: An imperative vision, where the message flows are defined explicitly, and a declarative one, where such flows are described as a collection of constraints to be respected.
We will present an approach that integrates both the operational and the declarative flavours of CC programs. By relying on a (timed) concurrent constraint programming language, we show that in addition to the usual operational techniques from process calculi, a CC program can elegantly exploit logic-based reasoning techniques coming from its declarative transformation. I will discuss some details of the approach, as well as some of the challenges.

About the presenter: Postdoct at FCUL-DI

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## Agent-Based Modelling and Simulation Systems (ABMS): Research Opportunities for Pest Control and Marine Resource Management in Azores

When: Thursday, 2015-Jan-15, 11h30-12h00
Where: FCUL-DI, room C6.3.05
Presenter: José Cascalho

Abstract: In this talk I will present two research contexts for Agent-Based Modeling and Simulation to study complex human and natural systems (CHANS). The contexts are the Pest Control Management in Azorean Islands and the Sustainable Resource Management in Azorean sea. These contexts are interesting because they simulate real contexts, comprise great amounts of data and, foremost, address the interaction between human decision-making and the environment. Along the talk will be presented a brief description of each one of these contexts, their goals and the different possible research threads associated to each one of these contexts.

Slides Here

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## Understanding the Accessibility barriers of the Blind when interacting with TV

When: Wednesday, 2014-Dec-17, 11h30-12h00
Where: FCUL-DI, room C6.3.05
Presenter: Daniel Costa

Abstract: Connected TV is an advanced broadcasting technology that provides a better experience in terms of picture and sound quality and enables interactive capabilities, while extending the reach of content by enabling access to Internet’s multimedia content. As this technology becomes common it is paramount that these new features are accessible by all. In this talk I will show the ongoing work I have been doing on my PhD regarding the evaluation of the current state of the accessibility on TVs. In the end we will engage on a brainstorm session about the next step to enhance blind users interaction.

Slides Here

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## On-Body Interaction for Optimized Accessibility

When: Wednesday, 2014-Dec-10, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: David Costa

Abstract: In this Smalltalk I will present you the motivation and goals of my thesis, the current work and a brief brainstorm session. My thesis addresses the suitability of Skin interaction when used by persons with different levels of visual impairment. I will also present a sEMG gesture recognizer and the initial results of an user experiment. Finally I want to engage in a brainstorm with the audience in order to discuss possible paths on how to study and observe blind users reaction and behaviour with skin interaction systems and the capacity of mapping various interaction elements on their body.

About the presenter: Ph.D. student / researcher at LaSIGE HCIM

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## Detection of web application vulnerabilities using sequence models

When: Thursday, 2014-Dec-04, 11h30-12h00
Where: FCUL-DI, room C6.3.05
Presenter: Ibéria Medeiros

Abstract: In this smalltalk, I will present a new static analysis method to detect web application vulnerabilities, as well the DEKANT mechanism that implements that method. Inspired in natural language processing (NLP), I use a sequence model — a Hidden Markov Model – to learn to characterize vulnerabilities based on a set of source code slices with its elements annotated as vulnerable or not. This knowledge takes into consideration the order in which the code elements appear in the slices, relating them. My goal is to collect opinions about the method and cases not covered by it to improve this work.

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## A review of some of the features introduced in Java SE 7

When: Thursday, 2014-Nov-27, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Ricardo Fonseca

Abstract: In this Smalltalk I will talk about some of the features introduced in Java SE 7. Although version 7 was introduced in the year 2011, some of its useful features may have been overlooked by programmers that started using Java before then. My goal is to remind people of these features, with focus on the area of Networking and Operating Systems.

Slides Here

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## Diego Kreutz — Towards Secure and Dependable Authentication and Authorization Infrastructures

When: Thursday, 2014-Nov-13, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Diego Kreutz

Abstract: We propose a resilience architecture for improving the security and dependability of authentication and authorization infrastructures, in particular the ones based on RADIUS and OpenID. This architecture employs intrusion- tolerant replication, trusted components and untrusted gateways to provide survivable services ensuring compatibility with standard protocols. The architecture was instantiated in two prototypes, one implementing RADIUS and another implementing OpenID. These prototypes were evaluated in fault-free executions, under faults, under attack, and in diverse computing environments. The results show that, beyond being more secure and dependable, our prototypes are capable of achieving the performance requirements of enterprise environments, such as IT infrastructures with more than 400k users.

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## Slack and Git are your best friends

When: Wednesday, 2014-Oct-29, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Carlos Mão de Ferro

Abstract: If you are not a solitaire cowboy while coding your masterpieces than you got to know two important tools: Git and Slack. Come to the next smalltalk and I will tell you about these tools and how they can speed up you team work and have a lot of fun at the same time.

Slides Here

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## Data structures for big data — Bloom filter

When: Thursday, 2014-Oct-16, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Vinicius Cogo

Abstract: In this smalltalk, the presenter will describe the Bloom filter (BF) data structure, as well as present known use cases in big data and some existent implementations. BFs are space-efficient probabilistic data structures for membership testing (i.e., test if an element belongs or not to a large dataset).

Slides Here

About the presenter: Ph.D student at FCUL-DI

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## Atração de novos alunos para a LEI e LTI

When: Thursday, 2014-Oct-09, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Luís Correia

Abstract: Discussão de iniciativas em curso e outras possibilidades para melhorar a captação de novos alunos nas licenciaturas em informática da FCUL.

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## Can we model Risk Perception?

When: Thursday, 2014-Sep-25, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Nuno Magessi

Abstract: In this smalltalk I’ll explain the importance of modelling risk perception by using agent based model methodology. In what concerns risk, perception is a critical step that occurs before decision making process and influences the way in how we decide under uncertainty conditions. The relevance of perception is so important that we need to distinguish perceived risk from effective risk. Tax evasion is an excellent case study to tackled this problem.

About the presenter: Nuno Trindade Magessi, Ph.D. student / researcher @ LabMAg working in collaboration with Luis Antunes. My research interests are Risk, Artificial and Neuro economics.

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## Distributed Deadlock Detection for Barrier Synchronisation

When: Wednesday, 2014-Sep-17, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Tiago Cogumbreiro

Abstract: A major part of deadlock detection is the maintenance of the concurrency constraints between tasks and blocking operations (e.g., barriers). Since barriers are collective operations, their analysis requires information distributed among various tasks. To improve the scalability of distributed deadlock detection, we propose an alternative representation that is oblivious of the status of the barrier operation—a global property—and instead considers the local impact of each task in the global ordering of barrier synchronisation.

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## SMALL-ABSTRACTS

As the DI-Smalltalks series restarts in this 1st semester of 2014/2015, we introduce a new recommendation for “abstracts” (a.k.a. “small-abstracts”), as a further step to promote the “smalltalks” concept (concise, informal, interactive, …). The following items, taken from https://smalltalks.di.fc.ul.pt/about, are ordered by importance (most important first):

SMALL-ABSTRACT:

1. write it with less than 101 words (if it is larger, the readers may become doubtful about the “small” in “Smalltalk”);
2. say what you will do in this specific presentation and what is your goal, e.g., “In this smalltalk, I/we will …” (rather than being a copy-paste of a paper abstract);
3. say how you will promote interaction with the audience and what the audience will learn by coming to your presentation (e.g., “I will ask suggestions from the audience about…” or “we will engage in a brainstorming to obtain ideas…”).

Note: to compensate the short size, we can include an external link to a related paper or longer abstract.

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## Online Autonomous Learning Agents

When: Wednesday, 2014-Jul-16, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Davide Nunes

Abstract: Evolutionary Computation has been successfully used to synthesise controllers for embodied agents and multiagent systems in general. Notwithstanding this, continuous on-line adaptation by the means of evolutionary algorithms is still under-explored. In this talk, I present an online evolutionary programming approach that searches in the agent design space for the appropriate behavioural policies to cope with the underlying environment. I will discuss the current problems of continuous agent coadaptation. The talk will be then directed towards brainstorming and open discussion of possible solutions and research directions for this work.

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## Low Level Error Detection For Real-Time Wireless Communications

When: Wednesday, 2014-Jul-09, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Jeferson Souza

Abstract:
The use of wireless networks to support communications with real-time restrictions is becoming a common requirement within environments such as industries, autonomous vehicles, and aerospace technologies, including also the support for cyber-physical systems (CPS). An effective real-time support on the wireless realm is still an open issue, relying on the presence of dependable and fault tolerant communication services, which are built upon fundamental mechanisms such as error detection. In this smalltalk we continue to explore the low levels of the networking protocol stack in the design of a robust foundation to efficiently support real-time on wireless networks; focused on low level error detection, we present the innovative idea to combine error protection mechanisms for enhancing the capabilities and accuracy of a wireless node in the detection of node failures.

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When: Thursday, 2014-Jul-03, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Pedro Ferreira (from I. P. Leiria)

Abstract:
The Internet of Things (IoT) is a buzzword that has emerged in the last decade. The concept indicates that real world objects attached to interconnected technological devices are things with the ability to share data and make decisions. All types of devices that have a connection to the internet are potential collaborators in different areas of the IoT: from industrial domains such as manufacturing or logistics to the life of everyone. These devices provide environment data that has the potential to empower enterprises business processes. Additionally, some devices with processing capabilities have the ability to execute process logic. However, business process modelling standards do not support language constructs to model the features of such devices. In this talk we discuss the challenges of modelling IoT devices gathered data in process modelling languages and the approaches to overcome them.

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## How to reduce the vulnerable window impact?

When: Wednesday, 2014-Jun-04, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Miguel Garcia

Abstract:
In this smalltalk I will explain how can we improve a service’s resilience by combining diversity and replication techniques. It is realistic to assume that all software contains vulnerabilities. However, some of these vulnerabilities can be more or less critical, and can be or not discovered and exploited. In this work we assume that all the critical vulnerabilities will eventually be exploited. Said that, one wants to deploy services or applications and be ready to respond to possible attacks, in such a way that the service and application keeps executing, in a correct way, even in the presence of intrusions. By combining replication techniques with component diversity we expect to make services more resilient. Some work was done to find if there is evidence that diversity can improve replicated system’s resilience. However, we still have work to do in order to guarantee that both diversity and replication when combined improve the system’s resilience.

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## Hadoop MapReduce Manager In Cloud-of-clouds

When: Wednesday, 2014-May-28, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Pedro Costa

Abstract:
MapReduce is used for processing large amounts of data using hundreds or thousands of machines. Hadoop MapReduce, its open-source implementation, tolerates machine failures and file corruptions. Despite their ability to tolerate the most common faults, these platforms are not prepared to deal with cloud faults, such as the outage of a whole datacenter. In this smalltalk I will present an Hadoop proxy that allows MapReduce computation to scale out to multiple clouds and to tolerate cloud faults. Our solution was designed with four objectives from the outset: First, it requires no modification to the Hadoop framework. Second, the proposed system tolerates Byzantine faults and cloud outages at reasonable cost. Third, it achieves its goal at reasonable cost by using different techniques to minimize computation, storage, and network data transfers. Fourth, it guarantees acceptable performance in terms of execution time.

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## Sobre a comissão pedagógica do doutoramento DI

When: Wednesday, 2014-May-21, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Comissão pedagógica PhD DI

Abstract:
Nesta smalltalk iremos conversar sobre a comissão pedagógica do doutoramento DI. A conversa começará com uma exposição informativa por parte dos atuais membros da comissão. Depois seguir-se-á um período de perguntas, com moderação, em que se pretende obter retorno construtivo por parte da audiência. A smalltalk é aberta a todos, desta vez dando-se especial destaque à participação de alunos de doutoramento. Esta será uma boa oportunidade para ganhar noção do enquadramento da comissão pedagógica e enumerar um conjunto de sugestões construtivas sobre ações da comissão e dos alunos para o ano letivo que se segue.

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## Reconfigurable Hardware: Design flow and Applications

When: Wednesday, 2014-Apr-30, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Ricardo Pinto

Abstract:
The ability to design and implement digital circuits to perform specific functions with considerable speedups at low costs has driven the development of reconfigurable logic devices. Reconfigurable hardware is an enabler technology in several domains, and Informatics is no exception, with the curriculum of most Computer Engineering degrees having a component focused in digital circuit design and applications. The development and implementation of current digital logic circuits has many similarities with the development of software, requiring skills similar to the ones required for parallel and concurrent programming. There are, however, some fundamental differences which can be eerie to people with software-only background. In this SmallTalk an overview of reconfigurable hardware will be given, ranging from the applications to the flow used for designing, implementing and testing digital logic systems. Some applications will be presented, together with an historical perspective on the development of reconfigurable devices.

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## Traffic Monitoring and Fault Injection in Wireless Sensor and Actuator networks

When: Wednesday, 2014-Apr-16, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Rui Caldeira

Abstract:
Wireless Sensor and Actuator Networks (WSANs) have become an interesting technology for supporting networking communications in different mixed-critical environments, from industrial to aerospace. Such communications are more exposed to errors, and as a consequence, frame transmissions can be subjected to corruption and loss; such loss may cause the necessity of retransmissions, additional traffic loads, unexpected delays, and, as a worst, the deviation of the communication service from its specification (unacceptable for mixed-critical environments). This smalltalk presents an under-development evaluation toolbox able to test and characterize the behavior of IEEE 802.15.4 WSANs under error conditions (emulated by fault injection techniques). This toolbox is based on the Wireshark Network Protocol Analyzer and Commercial Off-The-Shelf (COTS) hardware. Preliminary results will be presented to illustrate its potential and utility.

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## Raptor Codes

When: Wednesday, 2014-Apr-09, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: José Lopes

Abstract:
What if we could make UDP as reliable as TCP, but keep its inherent simplicity? Forward error correction (FEC) is a technique used in telecommunication to recover from errors occurred during data transmission.

In this Smalltalk we will be talking about Raptor codes, FEC schemes which promise “almost” reliable transmissions. I will introduce lots of new concepts and then we will be looking at the properties/evolution of fountain codes. Hopefully, you will find out why they are so awesome and that you should probably be using it!

A preview: http://www.slideshare.net/zemasa/fountain-codes

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## Real-Time Wireless Communications: An Overview and Future Directions

When: Wednesday, 2014-Apr-02, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Jeferson Souza

Abstract:
The use of wireless communications in environments with different levels of criticality has been grown within real-world scenarios. Industrial automation, inter-vehicular and intra-vehicular communications, disaster monitoring, and health monitoring are just few examples where such use is becoming effusive. As a consequence, the necessity to enhance the real-time capabilities of wireless communications is at the door, and active research has been done to accomplish it. This smalltalk presents an overview of the literature concerning the support of real-time guarantees in wireless communications, which includes the existent communication standards, in-development state-of-the-art architectures, and future directions of such research topic.

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## Tablet Canvas: Focus group on a new alternative way of interaction

When: Wednesday, 2014-Mar-26, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: José Coelho

Abstract:
More and more new ways of interaction with 21st century technology have been implemented in recent years, with special focus for smartphones and tablet devices. In most cases, the design of these new modalities is related with overcoming difficulties related with sensory, motor or cognitive characteristics of the users, as well as difficulties introduced by the different contexts of interactions where these technology can be used. This smalltalk has the goal of performing a focus group session with the several participants, where will be introduced a new way of interaction using a Tablet device canvas. Different interaction contexts will be explained, so that participants can give their own views regarding realistic use of the modality of interaction introduced. This is an exploratory discussion which will, if successful, result in practical use cases and in a new interaction modality. Therefore, and understanding that every one comes from a different research background, no previous knowledge regarding any type of technology will be needed to participate and all criticism and opinions are welcome.

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## Very-efficient flipping of many coins

When: Wednesday, 2014-Mar-12, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Luís Brandão

Abstract:
Coin-flipping is a basic cryptographic primitive that allows several parties to decide a common random bit-string. In this smalltalk I’ll talk in high level about a new method for coin-flipping very large bit-strings between two parties. The protocol achieves simulation-based security (a sophisticated notion of security) and improves efficiency over prior protocols. Some minutes of the smalltalk will be reserved for reflection about the security properties that such functionality should satisfy, and when some security properties can or should not be sacrificed in detriment of efficiency.

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When: Wednesday, 2014-Mar-05, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Bruno Vavala

Abstract:
Trusted Computing has gained lots of attention in the past few years. The need to provide verifiable guarantees for security-sensitive applications outsourced to untrusted hosts, such as Clouds or Content Distribution Networks, has fostered the development of security techniques based on trusted hardware. In this talk, I am going to review how these techniques have evolved recently, providing example applications that have been suggested and some current and future work.

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## LX-ListQuestion – Answering List Questions using Web as a corpus

When: Wednesday, 2014-Feb-19, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Patrícia Gonçalves

Abstract:
With the growth of the Internet, more people are searching for information on the Web. The combination of web growth and improvements in Information Technology has reignited the interest in Question Answering (QA) systems. In a search engine, the user inserts a few keywords and gets as a result links and snippets. The task of finding the desired answer among the results that were returned then falls on the user. From the point of view of QA, in turn, the users use a question in natural language and the system searches within the documents for the answers. Our purpose is to provide better QA solutions to users, who desire direct answers to their queries, using approaches that deal with the complex problem of extracting answers found spread over several documents and use them to compile a list of answers and presents them in the form of a Word Cloud

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## Serializing Data with Protocol Buffers

When: Wednesday, 2014-Feb-12, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Vinícius Cogo

Abstract:
Serializing data is the process of translating data structures or objects to a format that can be stored or transmitted to any entity, and subsequently reconstructed in any environment. It is important for most computing areas, including all those studied in our department (e.g., distributed systems, bioinformatics, data mining, natural language processing, robotics, etc.). In this SmallTalk, the presenter will introduce (1) the problems of data serialization and (2) the Protocol Buffers, a solution for this process launched by Google in 2008.

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## Reflecting about proofs of security

When: Wednesday, 2014-Jan-29, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Luís Brandão

Abstract:
In this smalltalk I’ll be presenting some ideas about proofs of security, motivated by some simple examples from cryptography. How can we prove that a protocol is secure? How do we even start by defining “security”? Some subtle notions tend to ruin the security of systems, as we find that they are attacked from an angle different from what had been previously imagined. What about that unbreakable door, circumvented by one that chooses to enter through the window? Hopefully you’ll leave the room at 12h00 with more questions than answers. P.S. You’ll be safe during this secure presentation!

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## Hands-on Geni

When: Wednesday, 2013-Dec-11, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Pedro Costa

Abstract:
Introduction to the Geni networks with a full example. People that have access to the Geni testbed can bring the computer.

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## Languages can save parallel programming

When: Wednesday, 2013-Oct-30, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Vasco Vasconcelos

Abstract:
Why is developing concurrent, distributed, and parallel applications so difficult? Abstractions are failing us; we need a fresh start and programming languages can help.

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## Analysing and Reducing Network Inaccessibility IEEE 802.15.4 Wireless Communications

When: Wednesday, 2013-Oct-16, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Jeferson Souza

Abstract:
Network inaccessibility is a temporal issue derived from the presence of faults affecting the communication services provided by the medium access control (MAC) sublayer. The occurrence of network inaccessibility represents temporary “communication blackouts”, which prevent communications to be performed and may imply disruptions of network operation, therefore compromising the dependability and timeliness of communications. This paper uses an analytical model accounting for network inaccessibility periods in wireless sensor and actuator networks, presenting the IEEE 802.15.4 standard as a case study. The analytical model is then used to derive a set of simple, yet quite effective policies to reduce the durations of the periods of network inaccessibility. The effectiveness of these policies can be evaluated using a tool based on the analytical model, which is being integrated in the NS-2 simulator for validation. Reducing network inaccessibility is a crucial step to enable the use of wireless networking technologies in real-time settings.

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## OWL Ontologies — Large files being constantly read

When: Wednesday, 2013-Oct-09, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: João Ferreira

Abstract:
Querying an ontology can be used to retrieve several bits of information. Eg, “is the heart a organ?”

But biomedical ontologies are usually large, with several hundred MB per file. Opening and parsing these files to answer a simple question is impractical. Solutions are:
(1) to open a file in a server process and have several clients query this server process (a là MySQL);
(2) to store this information in a database, so that it is readily available to be queried by any client.

Together, I’d like to harness the critical thinking power of the audience in order to find the pros and cons of each solution.

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## How to program from multicores to clusters using X10

When: Wednesday, 2013-Sep-25, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Tiago Cogumbreiro

Abstract:
X10 is a parallel programming language designed with usability and productivity in mind. It boasts a modern object oriented model, an expressive distributed programming model, and structured parallel constructs. Currently, it can be compiled to an MPI or to a Java application. In this tech session, we will learn the good, the bad, and the ugly of X10 parallel programming. Bring your laptop, your favorite text editor, the JRE, and the X10 SDK*, for good measure.

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## How to use threads+processes+queues in Python

When: Thursday, 2013-Sep-19, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Pedro Costa

Abstract:
In this session I will talk about concurrency in Python, and describe the advantages of using thread, processes and queues.

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## Threat vectors of Software-Defined Networks

When: Tuesday, 2013-Jul-18, 11h30-12h00
Where: FCUL-DI, room C6.3.37
Presenter: Diego Kreutz

Abstract:
The main goal of this small talk is to introduce some of the threat vectors of Software-Defined Networks (SDNs). After this, we will discuss some requirements and techniques that can help increase the security and dependability of SDNs.

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## Taming the concurrency beast via static analysis

When: Tuesday, 2013-Jul-09, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Hugo Vieira

Abstract:
Concurrent systems are hard to get right. The number of possible behaviors easily leaves a dynamic analysis (e.g., simulation, model-checking) without answer, not to mention a team of programmers, so it is virtually impossible to certify a posteriori that systems will perform as they are supposed to. One way to get things right is to use static analysis techniques that single out systems that enjoy good properties (even at the cost of losing some false negatives along the way), avoiding the deployment of buggy programs and saving on maintenance costs. In this talk we will briefly discuss the main artifacts involved in working with static analysis techniques, namely type systems, that focus on concurrent communication-centred programs.

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## Ontologies: multi-function tools for data representation and mining

When: Tuesday, 2013-Jul-02, 11h30-12h00
Where: FCUL-DI, room C6.3.38

Abstract:
Ontologies are structured and formal representations of knowledge, providing the definition of concepts and the relations between them. In this presentation, I’m going to give an overview of the use of ontologies, as well as present some concrete use-cases. In my work, ontologies are used in the biomedical context. However, ontologies exist for several domains of knowledge (e.g. linguistics, geography), and thus can be used in various contexts. Based on this, I expect to establish a discussion with the audience on how ontologies could be used in their work (or how they are already being using).

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When: Tuesday, 2013-Jun-25, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Oleksandr Malichevskyy

Abstract:
RADIUS and OpenID are two completely different protocols and have two different architectures. Each of protocols has a different proposal and usage. RADIUS is a low-level protocol which provides authentication, authorization and accounting for wired and wireless networks. OpenID is a high-level protocol implemented over HTTP protocol and is used to authenticate user using his identity provider, such as Facebook, Google, etc. We propose an architecture and proof of concept, where we will use two protocols, RADIUS and OpenID, as a unique replicated authentication service fully compatible with the current clients.

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## Machine Learning in High Dimensional Spaces

When: Monday, 2013-Jun-17, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Thibault Langlois

Abstract:
As the available computational power increases it is tempting to embrace more complex machine learning problems that involve larger amounts of data and higher dimensional spaces, with the hope of achieving greater precision. But in several application domains evidences are accumulating that a glass ceiling (in terms of performance) is being reached …

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## Consensus: Filter & Merge

When: Tuesday, 2013-Jun-11, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Miguel Garcia

Abstract:
In this Smalltalk I will present a “old” work that was forgotten in the drawer. The idea is simple, but without practical experiments I cannot validate – yet – the idea. The algorithm still needs some discussion. I propose a new way to do consensus in replicated system. A replica starts with a growing, “random”, unknown, non deterministic set, and should progress to a finite, deterministically formed set.

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## Visualising the movies

When: Tuesday, 2013-Jun-04, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Ana Jorge

Abstract:
I’m a designer and my research PhD is on visualisation with time-oriented data mostly in the video and movies’ context. The goal is to use visualization techniques to help the understanding and use of the information retrieved both from the outside space of the movies (e.g. date of release, genre, rate), and the contents inside the tracks (e.g. image, audio, subtitles).

I’ll speak shortly about: related work, main concepts and the role of design in information visualization, my contribution and what has been done already, next steps.

I’d like the audience to speak freely about what they think about presented functionalities, their pros and cons, and suggestions for future work.

I hope the audience can see a wider approach to information visualisation in opposition to the common computer engineering style, can know more about movies’ applications.

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## When replacing HDs with SSDs doesn’t solve your problem

When: Tuesday, 2013-May-28, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Alysson Bessani

Abstract:
SSDs are replacing disks in desktops, laptops and even in some servers. In this talk I’ll discuss why this is happening (i.e., the nice features of SSDs) and discuss a type of workload SSDs does present noticeable improvement over disks. Moreover, I’ll present some results showing (i.e., some bad features) that SSDs are not the right storage media for all applications.

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When: Wednesday, 2013-May-22, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Paulo Pombinho

Abstract:
Location based services have been made very popular by the recent generations of mobile devices that have become available. However, location information is not always available. For example, when the users are inside a building conventional positioning systems, like the GPS, are rendered useless. In this smalltalk I will present an adaptive algorithm for the detection of the indoor position of the users. This algorithm detects when the user is walking and the direction he/she is moving to infer the displacement done. Furthermore, we use information when the user is outdoors to calibrate the algorithm parameters to a specific user and the way he/she is currently moving.

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## DNA Privacy

When: Monday, 2013-May-13, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Vinícius Cogo

Abstract:
Would you like to have your DNA sequenced? In this smalltalk we will discuss the pros and cons in DNA sequencing, the importance of maintaining the privacy of DNA donors and the privacy risks involving this subject.

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## Designing Your Own CPU in Logisim

When: Tuesday, 2013-May-07, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Luís Marques

Abstract:
In this smalltalk we will see how to build our own CPU in Logisim. We will start with a quick overview of some fundamentals of digital logic, computer architecture and the Logisim simulator. Then we build a very simple CPU, step by step. The audience will help make some final improvements to the CPU. In general, this presentation will help the audience understand the general workings of CPUs, how different architectural decisions impact performance and cost.

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## Software-Defined Networking — Evolution or revolution?

When: Tuesday, 2013-Apr-30, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Diego Kreutz

Abstract:
Software-Defined Networking (SDN) looks to be the new norm in wireline and wireless networks. We are moving from static and proprietary communication infrastructures to open, dynamic and programmable networks. Three of the main key facets of this new world are openness, flexibility and a new pace for innovation. This small talk is an overview of SDN, highlighting also aspects of the evolution and revolution it is causing to the networks as we know. For instance, to a certain extend, the history of operating systems (e.g. GNU/Linux) is happening now at the network infrastructure domain. Furthermore, some ideas of challenges, open issues and upcoming solutions (needed or fostered by the market and academy) and opportunities will be discussed.

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## Videogames & Persuasion: Effectiveness, Power and Decay

When: Tuesday, 2013-Apr-23, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Luís Duarte

Abstract:
Videogames and persuasive technology are two intimately connected topics. Engaging players with compelling storylines, presenting inspiring musical scores or photo-realistic graphics and providing the player with an endless stream of unlockables are but a few of the strategies designers adopt to motivate their players. In this talk I will discuss some of the unexplored topics of this research field. In particular, the effectiveness of different persuasive strategies the motivational power of some techniques and the decay factor inherent to persuasion will be subject to debate.

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## Verifying Object Invariants with Dependent Types

When: Wednesday, 2013-Apr-03, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Joana Campos

Abstract:
In this smalltalk, I will present a simple dependently typed object-oriented language. Dependent types are types defined in terms of values that challenge the conventional distinction between the typechecking (compile-time) phase and execution (run-time) phase. I will discuss the language design based on a syntax-split approach that preserves a clear phase distinction. I will then go on to demonstrate how dependent types may be used in objects to specify and verify some kinds of properties. I will conclude with some ideas for extensions to handle mutable state and effects, as well as non-uniform dependencies involving multiple objects.

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## Visualization of Spatial-Temporal Information

When: Tuesday, 2013-Mar-19, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Tiago Gonçalves

Abstract:
In this small talk, I will present a small overview of my current PhD work. For that, I shall introduce the overall research questions/problems behind the visualization of spatio-temporal data, in general, and trajectory data, in particular. After that, I expect to give an overview about some of the existing visualization techniques for this type of data. To finish my presentation, and based on the idea that “everyone is a spatio-temporal analyst”, I intend to obtain some feedback regarding the audience’s familiarity with these techniques and discuss their possible applications for non-expert users.

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## Comparing and Quantifying the Chemical “Beauty” of Molecules

When: Tuesday, 2013-Mar-12, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Ana Teixeira

Abstract:
Ascertaining the similarity amongst molecules is a fundamental problem in cheminformatics. Given that similar molecules tend to have similar physico-chemical and biological properties, the notion of molecular similarity plays an important role in exploration of molecular structural space, query-retrieval in molecular databases, and in structure-property/activity modeling. Similarity is subjective and relies upon comparative judgments—there is no absolute standard of similarity, rather “like beauty, it is in the eye of the beholder”. Because of this subjectivity it is difficult to develop methods for unambiguously computing the similarities of large sets of molecules.

How similar is a given molecule to another? How do we quantify similarity? How do we decide when molecules are similar? We will discuss these questions using different examples. Finally, I will give an overview on the main existing methods to quantify structural similarity of molecules, including an outline of the method developed in the context of my work.

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## Web accessibility evaluation reporting

When: Tuesday, 2013-Mar-05, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Nádia Fernandes

Abstract:
In this small talk, I will introduce the essential topics of Web accessibility and Web accessibility evaluations. I will also present my evaluation methodology and its advantages and disadvantages. In this context, I will explain the current reporting procedures of the majority of the Web accessibility evaluators. Finally, I intend to discuss the best approaches to report accessibility problems in a useful and intuitive way.

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## Compositional hierarchical scheduling analysis: from real-time to real-life

When: Wednesday, 2013-Feb-27, 11h30-12h00
Where: FCUL-DI, room C6.3.05
Presenter: João Craveiro

Abstract
In this smalltalk, I’ll briefly introduce to you the essential concepts behind compositional analysis of hierarchical scheduling frameworks, with easy to grasp metaphors to help you understand them. Then, I’ll present the sketch of the idea of applying real-time scheduling in general, and this compositional analysis in particular, to model and analyze real-life situations. Ideally, we will then engage in some brainstorming about real-life situations for which this idea may fit.

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## Hadoop Map-Reduce in Cloud of Clouds

When: Tuesday, 2013-Feb-18, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Pedro Costa

Abstract:
MapReduce is a framework for processing large data sets largely used in cloud computing. MapReduce implementations like Hadoop can tolerate crashes and ﬁle corruptions, but there is evidence that general arbitrary faults do occur and can affect the correctness of job executions. In this presentation I will show a MapReduce version that tolerates arbitrary faults and runs in a set of clouds.

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## Programming Multicores Safely

When: Tuesday, 2013-Feb-12, 2013, 11h30-12h00
Where: FCUL-DI, room C6.3.05
Presenter: Tiago Cogumbreiro

Abstract:
The key to develop parallel applications in a scalable way lays in using synchronization mechanisms at the “right” level of abstraction. Languages and libraries come bundled with more high level parallel constructs than before to help developers avoid mistakes with ad hoc solutions. Barrier synchronization constructs, power most of these systems. The design of a barrier bears a compromise between expressiveness and its properties. We present a survey on barrier semantics and propose some extensions. Our goal is to seek applications that use advanced collective synchronization patterns.

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## Resilient and Real-Time Wireless Communications

When: Tuesday, 2013-Feb-05, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Jeferson Souza

Abstract:
Wireless communications are susceptible to numerous sources of interferences such as external electromagnetic waves, obstacles in communication path, or even glitches in the network device circuitry. These kind of interferences may disturb the network operation, causing node and frame errors and imposing dependability and timeliness issues, which may imply temporal hazards to networked real-time systems. In this talk we present a bottom-up approach to enhance the dependability and timeliness properties of wireless communications, therefore making wireless networks more resilient against network errors. An architecture dubbed Resilient and Real-Time Medium Access Control (${\cal R}2{\cal T}$-MAC) is presented, emphasizing the relationship between its internal components and the compliance with existent communication standards such as IEEE 802.15.4 and IEEE 802.11p.

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## Semantic Similarity

When: Tuesday, 2013-Jan-29, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: João Ferreira

Abstract:
Semantic similarity is a technique that allows the comparison of arbitrary concepts, provided they are formally encoded in a machine-readable format. It allows the comparison of terms like “leg”, “arm”, “heart” etc. We can explore this technique to provide biomedical (and other!) researchers with powerful tools. For example, this gives doctors the ability to fetch from a database cases that are similar to the one of the patient right in front of him. With the help of the audience, I will try to present some ways of doing similarity in the biomedical context.

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## Elderly and Tablets (and Facebook): Talking with Grandma

When: Monday, 2013-Jan-21, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: José Coelho

Abstract:
We present a novel way of motivating Social Network adoption by elderly users, by basing interaction and design of an existing service around family awareness. Following an approach based on a tablet device interaction and navigation through a family (genealogical) tree like interface, we provide relevant discussion related with the use of family as a central role in Social Network applications when concerning elderly, and present the initial prototype developed making use of Facebook API. Presentation is motivated by the first experience with a typical grandmother and has the goal of generating discussion among the audience.

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## Secure Two-Party Computation

When: Tuesday, 2013-Jan-15, 11h30-12h00
Where: FCUL-DI, room C6.3.38
Presenter: Luís Brandão

Abstract:
In this smalltalk, I will describe the goal of Secure Two Party Computation (a cryptographic functionality). As motivation, the audience will solve in practice, without math, two simple problems:

a) Imagine you think of a number between 1 and 5 and your friend also thinks of a number. Both feel embarassed to say your option, but would not mind learning only whether you are thinking of the same number or not. How can you do it?

b) After a first date, a couple would like to know if both like each other. How can they compute just that, without chance of one declaring his/her positive feelings while being rejected by the other? In other words: how to compute the Boolean AND-gate securely?

Based on this, I will motivate more complex applications, e.g., related with privacy of medical data, and ask the audience for ideas of applications where S2PC could bring an added social value.

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