6,514 research outputs found
Non-algebraic Examples of Manifolds with the Volume Density Property
Some Stein manifolds (with a volume form) have a large group of
(volume-preserving) automorphisms: this is formalized by the (volume) density
property, which has remarkable consequences. Until now all known manifolds with
the volume density property are algebraic, and the tools used to establish this
property are algebraic in nature. In this note we adapt a known criterion to
the holomorphic case, and give the first known examples of non-algebraic
manifolds with the volume density property: they arise as suspensions or
pseudo-affine modifications over Stein manifolds satisfying some technical
properties. As an application we show that there are such manifolds that are
potential counterexamples to the Zariski Cancellation Problem, a variant of the
Toth-Varolin conjecture, and the problem of linearization of C*-actions on C^3
Backward stochastic differential equation approach to modeling of gene expression
In this article, we introduce a novel backward method to model stochastic
gene expression and protein level dynamics. The protein amount is regarded as a
diffusion process and is described by a backward stochastic differential
equation (BSDE). Unlike many other SDE techniques proposed in the literature,
the BSDE method is backward in time; that is, instead of initial conditions it
requires the specification of endpoint ("final") conditions, in addition to the
model parametrization. To validate our approach we employ Gillespie's
stochastic simulation algorithm (SSA) to generate (forward) benchmark data,
according to predefined gene network models. Numerical simulations show that
the BSDE method is able to correctly infer the protein level distributions that
preceded a known final condition, obtained originally from the forward SSA.
This makes the BSDE method a powerful systems biology tool for time reversed
simulations, allowing, for example, the assessment of the biological conditions
(e.g. protein concentrations) that preceded an experimentally measured event of
interest (e.g. mitosis, apoptosis, etc.).Comment: Accepted in Physical Review
Visual Memories of the marble industry: Using Cinema and Photography in Mining Heritage Studies
The introduction of new techniques and technological equipment into the
Portuguese marble industry led to an exponential increase in production and,
consequently, to profound environmental and landscape changes. The fact that
the techniques had previously been adopted in other marble mining regions, like
Wallonia (Belgium) and Carrara (Italy), confirms the standardization of the
extraction and transformation process. However, despite using the same
technology, each region’s local know-how and landscape features gave rise to
different working contexts, many of which are not documented in written sources.
Indeed, moving images and iconography prove to be a relevant source for studying
local working techniques, machinery adaptations, or work distributions. Visual
sources can be used to update previous studies and produce new ones, such as
comparisons between quarrying techniques. Furthermore, these images prove to
be a suitable and appealing educational instrument to show how technology has
changed to allow firms to overcome market challenges and quarry vast mineral
deposits
Sistemas Não Cooperativos para Registo de Assiduidade em Ambiente de Sala de Aula
Over the years, high school dropout, college dropout, in particular, has always been a hot
topic. With the advancement of technology and Artificial Intelligence and Machine Learning, we necessarily have to think of ways to help mitigate this problem. If there are factors
that we cannot control, such as the economic ones, there are others where our actions can
be directed. One factor that allows us to evaluate the risk of dropping out of school is student attendance. Although this data can be manually analyzed to make these detections,
it would be more efficient to have a capable system of recording this attendance, since the
human capacity to analyze data is finite, and often can only infer this situation too late. Of
course, a system that only registers attendance will not give a definitive answer, but it will
be an essential first step. Thus, a system that can reconcile the detection of a subject and
his face while being able to constantly monitor where the subject is, always to be able to
identify him even if he moves from one place to another, together with facial recognition,
seem to be determining factors to bring a system of this calibre to a successful conclusion.
This type of system is generally very much related to the quality of the data and its annotations, so it is vital to collect or obtain quality data to help solve the various problems
presented.
Considering what has been described, the main goal of this dissertation is to try to start
solving the problem of school dropout, namely through the study, validation and testing of
several stateoftheart methods in the area of object detection, namely people and faces,
but also tracking. The same work will have to be done on face recognition methods, being able to indicate the best stateoftheart methods for each task. As mentioned in the
previous paragraph, a significant limitation to this type of task is the data quality since it
is not always possible to find a set that perfectly fits our context. Thus, to solve this gap,
we will also present a dataset with about 40,000 images, thoroughly annotated frame by
frame and that we believe to be an asset in solving this problem. In addition to the above,
and in order not only to give a more meaningful and targeted response to our detailed
data but also to provide a preliminary view of how one of the system’s tasks might work,
we will present two experiments with our data in the area of detection. The first will involve finetuning our data, while the second will involve training it from scratch and then
presenting its results as proof of the correct choice of the stateoftheart method.Ao longo dos anos, o abandono escolar, o universitário em particular, tem sido sempre
um tema em grande destaque. Com o avanço de várias áreas tecnológicas, assim como da
Inteligência Artificial e da Aprendizagem Automática temos necessariamente de pensar
em maneiras de ajudar a mitigar este problema. Se há fatores que não podemos controlar, como os económicos, há outros onde a nossa ação pode ser dirigida. Um dos fatores
que permite avaliar o risco de abandono escolar é a assiduidade dos estudantes. Embora,
naturalmente, estes dados possam ser analisados manualmente para fazer estas deteções,
seria mais eficiente ter um sistema que fosse capaz de registar esta assiduidade, uma vez
que a capacidade humana para os analisar é finita e muitas vezes apenas consegue inferir esta situação demasiado tarde. Naturalmente que um sistema que registe apenas
assiduidade não irá ser capaz de dar uma resposta definitiva, mas será um primeiro passe
importante. Deste modo, um sistema que seja capaz de conciliar a deteção de uma pessoa
e da sua face enquanto é capaz de monitorizar de forma constante o sítio onde a pessoa
está, para ser sempre capaz de a identificar mesmo que mude de sítio em conjunto com
o seu reconhecimento facial, parecem ser fatores determinantes para levar a bom porto
um sistema deste calibre. Este tipo de sistemas está, geralmente, muito relacionado com
a qualidade dos dados e das suas anotações, pelo que é extraordinariamente importante
ser capaz de recolher ou obter dados de qualidade que auxiliem na resolução dos diversos
problemas apresentados.
Tendo em atenção aquilo que foi sendo descrito, o principal objetivo desta dissertação
passa por tentar dar início à resolução do problema do abandono escolar, nomeadamente
através do estudo, validação e teste de diversos métodos estadodaarte no que diz respeito
à área da deteção de objetos, nomeadamente de pessoas e faces, mas também de tracking.
O mesmo trabalho terá de ser realizado nos métodos de reconhecimento facial, sendo capaz no final de poder indicar os melhores métodos estadodaarte de cada tarefa. Como
referido no parágrafo anterior, uma limitação grande a este tipo de tarefas é a respetiva
qualidade dos dados, visto que nem sempre e possível encontrar um conjunto que se adeque perfeitamente ao nosso contexto. Assim, de modo a solucionar esta lacuna iremos
também apresentar um dataset com cerca de 40,000 imagens, completamente anotado
frame a frame e que acreditamos ser uma mais valia na resolução deste problema. Para
além do referido, e de modo não só a dar uma resposta mais significativa e dirigida aos
nossos dados em particular, mas também para que seja possível ter uma visão preliminar
daquilo que poderá ser o funcionamento de uma das tarefas do sistema, iremos apresentar duas experiências com os nossos dados, na área da deteção. A primeira irá envolver o
finetuning dos nossos dados, enquanto que a segunda levará a um treino iniciado de raiz,
apresentando depois os seus resultados como uma prova da escolha acertada do método
de estado da arte
CORQ - Code Review for Quality Measurement
Trabalho de Projeto de Mestrado, Informática, 2022, Universidade de Lisboa, Faculdade de CiênciasThis report was developed based on the project held in the portuguese software company Opensoft in the context of my Master’s degree in Computer Science from September 6th 2021 to June 30th 2022.
Quality and productivity are some of, if not the most important factors in any software company in today’s reality for its growth and operation. Therefore, there is a need to obtain quality and productivity metrics for the work conducted by software developers. Code Review for Quality Measurement (as will be referenced from now on as CORQ) is a tool developed from scratch by a small team in Opensoft including me, which is
the software company where this tool was developed, for the purpose of this thesis, that provides metrics on the productivity and quality of software of a company’s employees, projects, or itself overall. The tool may only be used in Opensoft initially due to the interfaces that are used to obtain these metrics and the specifications needed to implement the project. This problem can be solved with future work, in case we want to expand the tool so it is usable in other software companies. CORQ intends to use multiple interfaces such as SonarQube, Jira, Confluence, Git repositories in Bitbucket and SVN repositories to obtain information about Opensoft’s
artifacts and thus calculates metrics on the productivity and quality of its employees and the software produced by them. With the use of CORQ it is expected for the company’s employees to be more motivated, increasing their productivity, saving human resources, and saving analysis time spent on the software produced. CORQ can be used complementary to code reviewing and other software quality assurance techniques and software
ESTRATÉGIAS GENÉRICAS DE COMPETIÇÃO PRATICADAS POR IES PRIVADAS DE PEQUENO PORTE
A partir do mapeamento da cadeia de valor genérica para o segmento de ensino superior e de uma pequena amostra de avaliações institucionais, baseadas no sistema SINAES (Sistema Nacional de Avaliação do Ensino Superior, proposto pelo Ministério da Educação), realizadas entre os anos de 2009 e 2010, este artigo identifica e discute estratégias desenvolvidas por IES Privadas de pequeno porte para sustentar uma posição competitiva no mercado Brasileiro, caracterizado atualmente por ser altamente competitivo, por serviços de commodity e com uma demanda decrescente e retraída. Para tanto, foi desenvolvido um estudo empírico e exploratório, com abordagem qualitativa, utilizando-se o método de estudos multicasos. As estratégias competitivas identificadas, seus resultados positivos e limitações sevem para indicar horizontes e possibilitar reflexões sobre a adoção de algumas práticas de gestão em IES privadas
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