1,852 research outputs found
Estimating labels from label proportions
Consider the following problem: given sets of unlabeled observations, each set with known label proportions, predict the labels of another set of observations, also with known label proportions. This problem appears in areas like e-commerce, spam filtering and improper content detection. We present consistent estimators which can reconstruct the correct labels with high probability in a uniform convergence sense. Experiments show that our method works well in practice.
Convex relaxation of mixture regression with efficient algorithms
We develop a convex relaxation of maximum a posteriori estimation of a mixture of regression models. Although our relaxation involves a semidefinite matrix variable, we reformulate the problem to eliminate the need for general semidefinite programming. In particular, we provide two reformulations that admit fast algorithms. The first is a max-min spectral reformulation exploiting quasi-Newton descent. The second is a min-min reformulation consisting of fast alternating steps of closed-form updates. We evaluate the methods against Expectation-Maximization in a real problem of motion segmentation from video data
Kernel conditional quantile estimation via reduction revisited
Quantile regression refers to the process of estimating the quantiles of a conditional distribution and has many important applications within econometrics and data mining, among other domains. In this paper, we show how to estimate these conditional quantile functions within a Bayes risk minimization framework using a Gaussian process prior. The resulting non-parametric probabilistic model is easy to implement and allows non-crossing quantile functions to be enforced. Moreover, it can directly be used in combination with tools and extensions of standard Gaussian Processes such as principled hyperparameter estimation, sparsification, and quantile regression with input-dependent noise rates. No existing approach enjoys all of these desirable properties. Experiments on benchmark datasets show that our method is competitive with state-of-the-art approaches.
EurOcean 2014. Connecting Science, Policy and People. Conference report and Rome Declaration 7-9 October 2014, Rome, Italy
This publication presents the Conference Report from EurOCEAN 2014 – a major European marine science policy conference which took place on 7-9 October 2014 in Rome, Italy. The report provides the key messages from the Conference including the Rome Declaration, a consensus view of some 340 participants spanning science, policy and industry. The Declaration sets a vision for seas and ocean science to achieve an ecosystem approach to the management of Europe’s marine resources as a fundamental requirement for sustainable Blue Growth whilst driving European leadership in marine science and technology. EurOCEAN 2014 was an official event of the Italian Presidency of the Council of the European Union, co-organized by the European Marine Board (EMB), the European Commission (Directorate-General for Research and Innovation), the Italian National Research Council (CNR), National Inter-university Consortium for Ocean Science (CoNISMa), and the National Institute of Oceanography and Experimental Geophysics (OGS
Multitask learning without label correspondences
We propose an algorithm to perform multitask learning where each task has potentially distinct label sets and label correspondences are not readily available. This is in contrast with existing methods which either assume that the label sets shared by different tasks are the same or that there exists a label mapping oracle. Our method directly maximizes the mutual information among the labels, and we show that the resulting objective function can be efficiently optimized using existing algorithms. Our proposed approach has a direct application for data integration with different label spaces for the purpose of classification, such as integrating Yahoo! and DMOZ web directories
Salvage Flexor Hallucis Longus Transfer for a Failed Achilles Repair: Endoscopic Technique
Flexor hallucis longus (FHL) transfer is a well-established treatment option in failed Achilles tendon (AT) repair and has been routinely performed as an open procedure. We detail the surgical steps needed to perform an arthroscopic transfer of the FHL for a chronic AT rupture. The FHL tendon is harvested as it enters in its tunnel beneath the sustentaculum tali; a tunnel is then drilled in the calcaneus as near to the AT footprint as possible. By use of a suture-passing device, the free end of the FHL is advanced to the plantar aspect of the foot. After adequate tension is applied to the construct, the tendon is fixed in place with an interference screw in an inside-out fashion. This minimally invasive approach is a safe and valid alternative to classic open procedures with the obvious advantages of preserving the soft-tissue envelope and using a biologically intact tendon
Rendimento de grãos e algumas características agronômicas de cultivares de trigo avaliadas na região de Pelotas-RS, em 2003.
bitstream/item/31641/1/comunicado107.pd
M\"obius and twisted graphene nanoribbons: stability, geometry and electronic properties
Results of classical force field geometry optimizations for twisted graphene
nanoribbons with a number of twists varying from 0 to 7 (the case =1
corresponds to a half-twist M\"obius nanoribbon) are presented in this work.
Their structural stability was investigated using the Brenner reactive force
field. The best classical molecular geometries were used as input for
semiempirical calculations, from which the electronic properties (energy
levels, HOMO, LUMO orbitals) were computed for each structure. CI wavefunctions
were also calculated in the complete active space framework taking into account
eigenstates from HOMO-4 to LUMO+4, as well as the oscillator strengths
corresponding to the first optical transitions in the UV-VIS range. The lowest
energy molecules were found less symmetric than initial configurations, and the
HOMO-LUMO energy gaps are larger than the value found for the nanographene used
to build them due to electronic localization effects created by the twisting. A
high number of twists leads to a sharp increase of the HOMO LUMO
transition energy. We suggest that some twisted nanoribbons could form crystals
stabilized by dipolar interactions
Sistema de apoio à condução de uma cadeira de rodas
Neste trabalho é apresentada a conceção prática de uma cadeira de rodas elétrica destinada a ser usadas por pessoas com graves limitações físicas.
É feita a descrição do módulo de hardware/software desenvolvido, responsável pela aquisição de diferentes sinais de entrada, como a distância da cadeira aos objetos e a velocidade da cadeira. Estes sinais permitem que o sistema adeqúe a velocidade dos movimentos ao ambiente em que se encontra.
É descrito também um segundo módulo constituído por hardware/software que é responsável pelo controlo da potência dos motores da cadeira. Neste módulo é controlada a potência dos motores da cadeira elétrica, de forma a obter um movimento com as características pretendidas pelo utilizador.
Por último, apresenta-se o desenvolvimento de um módulo de software que cria uma interface padrão entre os dois módulos apresentados e os diferentes sistemas de interação adaptados a cada utilizador. Deste modo, o sistema de controlo da cadeira poderá ter diferentes formas de interação com o utilizador, escolhendo-se aquela que mais potencia as suas capacidades, como por exemplo a voz, o olhar, um joystick, um sinal electromiográfico entre outros possíveis.
No final são apresentados os testes efetuados com um utilizador real e os resultados obtidos
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