83 research outputs found
Melanocortin peptides inhibit urate crystal-induced activation of phagocytic cells
Introduction The melanocortin peptides have marked antiinflammatory
potential, primarily through inhibition of
proinflammatory cytokine production and action on phagocytic
cell functions. Gout is an acute form of arthritis caused by the
deposition of urate crystals, in which phagocytic cells and
cytokines play a major pathogenic role. We examined whether
alpha-melanocyte-stimulating hormone (\u3b1-MSH) and its
synthetic derivative (CKPV)2 influence urate crystal-induced
monocyte (Mo) activation and neutrophil responses in vitro.
Methods Purified Mos were stimulated with monosodium urate
(MSU) crystals in the presence or absence of melanocortin
peptides. The supernatants were tested for their ability to induce
neutrophil activation in terms of chemotaxis, production of
reactive oxygen intermediates (ROIs), and membrane
expression of CD11b, Toll-like receptor-2 (TLR2) and TLR4. The
proinflammatory cytokines interleukin (IL)-1\u3b2, IL-8, and tumor
necrosis factor-alpha (TNF-\u3b1) and caspase-1 were determined
in the cell-free supernatants. In parallel experiments, purified
neutrophils were preincubated overnight with or without
melanocortin peptides before the functional assays.
Results The supernatants from MSU crystal-stimulated Mos
exerted chemoattractant and priming activity on neutrophils,
estimated as ROI production and CD11b membrane
expression. The supernatants of Mos stimulated with MSU in the
presence of melanocortin peptides had less chemoattractant
activity for neutrophils and less ability to prime neutrophils for
CD11b membrane expression and oxidative burst. MSU crystalstimulated
Mos produced significant levels of IL-1\u3b2, IL-8, TNF-\u3b1,
and caspase-1. The concentrations of proinflammatory
cytokines, but not of caspase-1, were reduced in the
supernatants from Mos stimulated by MSU crystals in the
presence of melanocortin peptides. Overnight incubation of
neutrophils with the peptides significantly inhibited their ability to
migrate toward chemotactic supernatants and their capacity to
be primed in terms of ROI production.
Conclusions \u3b1-MSH and (CKPV)2 have a dual effect on MSU
crystal-induced inflammation, inhibiting the Mos' ability to
produce neutrophil chemoattractants and activating
compounds and preventing the neutrophil responses to these
proinflammatory substances. These findings reinforce previous
observations on the potential role of \u3b1-MSH and related
peptides as a new class of drugs for treatment of inflammatory
arthritis
Compulsory Flow Q-Learning: an RL algorithm for robot navigation based on partial-policy and macro-states
Reinforcement Learning is carried out on-line, through trial-and-error interactions of the agent with the environment, which can be very time consuming when considering robots. In this paper we contribute a new learning algorithm, CFQ-Learning, which uses macro-states, a low-resolution discretisation of the state space, and a partial-policy to get around obstacles, both of them based on the complexity of the environment structure. The use of macro-states avoids convergence of algorithms, but can accelerate the learning process. In the other hand, partial-policies can guarantee that an agent fulfils its task, even through macro-state. Experiments show that the CFQ-Learning performs a good balance between policy quality and learning rate.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)GRICESFAPESPCNP
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Agents Teaching Agents: A Survey on Inter-agent Transfer Learning
Autonomous Agents and Multi-Agent Systems published a piece about the Inter-agent Transfer Learning in January 2020.Office of the VP for Researc
A step towards a reinforcement learning de novo genome assembler
The use of reinforcement learning has proven to be very promising for solving
complex activities without human supervision during their learning process.
However, their successful applications are predominantly focused on fictional
and entertainment problems - such as games. Based on the above, this work aims
to shed light on the application of reinforcement learning to solve this
relevant real-world problem, the genome assembly. By expanding the only
approach found in the literature that addresses this problem, we carefully
explored the aspects of intelligent agent learning, performed by the Q-learning
algorithm, to understand its suitability to be applied in scenarios whose
characteristics are more similar to those faced by real genome projects. The
improvements proposed here include changing the previously proposed reward
system and including state space exploration optimization strategies based on
dynamic pruning and mutual collaboration with evolutionary computing. These
investigations were tried on 23 new environments with larger inputs than those
used previously. All these environments are freely available on the internet
for the evolution of this research by the scientific community. The results
suggest consistent performance progress using the proposed improvements,
however, they also demonstrate the limitations of them, especially related to
the high dimensionality of state and action spaces. We also present, later, the
paths that can be traced to tackle genome assembly efficiently in real
scenarios considering recent, successfully reinforcement learning applications
- including deep reinforcement learning - from other domains dealing with
high-dimensional inputs
General detection model in cooperative multirobot localization
The cooperative multirobot localization problem consists in localizing each robot in a group within the same environment, when robots share information in order to improve localization accuracy. It can be achieved when a robot detects and identifies another one, and measures their relative distance. At this moment, both robots can use detection information to update their own poses beliefs. However some other useful information besides single detection between a pair of robots can be used to update robots poses beliefs as: propagation of a single detection for non participants robots, absence of detections and detection involving more than a pair of robots. A general detection model is proposed in order to aggregate all detection information, addressing the problem of updating poses beliefs in all situations depicted. Experimental results in simulated environment with groups of robots show that the proposed model improves localization accuracy when compared to conventional single detection multirobot localization.FAPESPCNP
Reinforcement Learning Applied to Trading Systems: A Survey
Financial domain tasks, such as trading in market exchanges, are challenging
and have long attracted researchers. The recent achievements and the consequent
notoriety of Reinforcement Learning (RL) have also increased its adoption in
trading tasks. RL uses a framework with well-established formal concepts, which
raises its attractiveness in learning profitable trading strategies. However,
RL use without due attention in the financial area can prevent new researchers
from following standards or failing to adopt relevant conceptual guidelines. In
this work, we embrace the seminal RL technical fundamentals, concepts, and
recommendations to perform a unified, theoretically-grounded examination and
comparison of previous research that could serve as a structuring guide for the
field of study. A selection of twenty-nine articles was reviewed under our
classification that considers RL's most common formulations and design patterns
from a large volume of available studies. This classification allowed for
precise inspection of the most relevant aspects regarding data input,
preprocessing, state and action composition, adopted RL techniques, evaluation
setups, and overall results. Our analysis approach organized around fundamental
RL concepts allowed for a clear identification of current system design best
practices, gaps that require further investigation, and promising research
opportunities. Finally, this review attempts to promote the development of this
field of study by facilitating researchers' commitment to standards adherence
and helping them to avoid straying away from the RL constructs' firm ground.Comment: 38 page
Markov decision processes for ad network optimization
In this paper we examine a central problem in a particular advertising\ud
scheme: we are concerned with matching marketing campaigns that produce\ud
advertisements (“ads”), to impressions — where “impression” is a general term\ud
for any space in the internet that can display an ad. In this paper we propose a\ud
new take on the problem by resorting to planning techniques based on Markov\ud
Decision Processes, and by resorting to plan generation techniques that have\ud
been developed in the AI literature. We present a detailed formulation of the\ud
Markov Decision Process approach and results of simulated experimentsAnna Helena Reali Costa and F ́ abio Gagliardi Cozman are partially supported by CNPq. Fl ́ avio Sales Truzzi is supported by CAPES. The work reported here has received sub- stantial support through FAPESP grant 2008/03995-5 and FAPESP grant 2011/19280-
DEBACER: a method for slicing moderated debates
Subjects change frequently in moderated debates with several participants, such as in parliamentary sessions, electoral debates, and trials. Partitioning a debate into blocks with the same subject is essential for understanding. Often a moderator is responsible for defining when a new block begins so that the task of automatically partitioning a moderated debate can focus solely on the moderator's behavior. In this paper, we (i) propose a new algorithm, DEBACER, which partitions moderated debates; (ii) carry out a comparative study between conventional and BERTimbau pipelines; and (iii) validate DEBACER applying it to the minutes of the Assembly of the Republic of Portugal. Our results show the effectiveness of DEBACER.info:eu-repo/semantics/publishedVersio
Realidade Virtual: Estereoscopia na Educação
Realidade virtual (RV) na educação é um tema fortemente presente nas instituições de pesquisas de vários países. Este artigo discute a aplicação de técnicas de RV, incluindo o uso da computação gráfi ca e a produção de vídeos tridimensionais a partir de equipamentos específi cos, porém de baixo custo para instituições de ensino. A estereoscopia atua como ponto chave para a visualização dessas aplicações. Para o desenvolvimento do projeto, são utilizados uma lente 3D, câmera doméstica, projetores de baixo custo, fi ltros de luz polarizados e óculos 3D passivo. O objetivo da produção do vídeo 3D foi o de avaliar desde os processos envolvidos na elaboração de roteiro, gravação e exibição, até os custos necessários para que uma instituição de ensino adote recursos de realidade virtual para o aprimoramento da aprendizagem
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