3,028 research outputs found
Fisher Vectors Derived from Hybrid Gaussian-Laplacian Mixture Models for Image Annotation
In the traditional object recognition pipeline, descriptors are densely
sampled over an image, pooled into a high dimensional non-linear representation
and then passed to a classifier. In recent years, Fisher Vectors have proven
empirically to be the leading representation for a large variety of
applications. The Fisher Vector is typically taken as the gradients of the
log-likelihood of descriptors, with respect to the parameters of a Gaussian
Mixture Model (GMM). Motivated by the assumption that different distributions
should be applied for different datasets, we present two other Mixture Models
and derive their Expectation-Maximization and Fisher Vector expressions. The
first is a Laplacian Mixture Model (LMM), which is based on the Laplacian
distribution. The second Mixture Model presented is a Hybrid Gaussian-Laplacian
Mixture Model (HGLMM) which is based on a weighted geometric mean of the
Gaussian and Laplacian distribution. An interesting property of the
Expectation-Maximization algorithm for the latter is that in the maximization
step, each dimension in each component is chosen to be either a Gaussian or a
Laplacian. Finally, by using the new Fisher Vectors derived from HGLMMs, we
achieve state-of-the-art results for both the image annotation and the image
search by a sentence tasks.Comment: new version includes text synthesis by an RNN and experiments with
the COCO benchmar
The optical properties of the Woodburytype - An alternative printing technique based on a gelatine/pigment matrix
© 2019 Society for Imaging Science and Technology The Woodburytype is a 19th century photomechanical technique, producing high-quality continuous-tone prints that use a mixture of pigment and gelatine as a relief print, in which the variation in height of the print produces the tone and contrast. We propose a phenomenological optical model for the process based on Kubelka-Munk theory that considers the ink formulation, the print height and the substrate surface in order to provide the ideal combination of printing depth and contrast
Analysing and modelling train driver performance
Arguments for the importance of contextual factors in understanding human performance have been made extremely persuasive in the context of the process control industries. This paper puts these arguments into the context of the train driving task, drawing on an extensive analysis of driver performance with the Automatic Warning System (AWS). The paper summarises a number of constructs from applied psychological research which are thought to be important in understanding train driver performance. A “Situational Model” is offered as a framework for investigating driver performance. The model emphasises the importance of understanding the state of driver cognition at a specific time (“Now”) in a specific situation and a specific context
10 um wavefront spatial filtering: first results with chalcogenide fibers
Wavefront cleaning by single-mode fibers has proved to be efficient in
optical-infrared interferometry to improve calibration quality. For instance,
the FLUOR instrument has demonstrated the capability of fluoride glass
single-mode fibers in this respect in the K and L bands. New interferometric
instruments developped for the mid-infrared require the same capability for the
8-12 um range. We have initiated a program to develop single-mode fibers in the
prospect of the VLTI mid-infrared instrument MIDI and of the ESA/DARWIN and
NASA/TPF missions that require excellent wavefront quality. In order to
characterize the performances of chalcogenide fibers we are developping, we
have set up an experiment to measure the far-field pattern radiated at 10 um.
In this paper, we report the first and promising results obtained with this new
component.Comment: Conference "Interferometry for Optical Astronomy II", SPIE 200
Antidiabetes and Anti-obesity Activity of Lagerstroemia speciosa
The leaves of Lagerstroemia speciosa (Lythraceae), a Southeast Asian tree more commonly known as banaba, have been traditionally consumed in various forms by Philippinos for treatment of diabetes and kidney related diseases. In the 1990s, the popularity of this herbal medicine began to attract the attention of scientists worldwide. Since then, researchers have conducted numerous in vitro and in vivo studies that consistently confirmed the antidiabetic activity of banaba. Scientists have identified different components of banaba to be responsible for its activity. Using tumor cells as a cell model, corosolic acid was isolated from the methanol extract of banaba and shown to be an active compound. More recently, a different cell model and the focus on the water soluble fraction of the extract led to the discovery of other compounds. The ellagitannin Lagerstroemin was identified as an effective component of the banaba extract responsible for the activity. In a different approach, using 3T3-L1 adipocytes as a cell model and a glucose uptake assay as the functional screening method, Chen et al. showed that the banaba water extract exhibited an insulin-like glucose transport inducing activity. Coupling HPLC fractionation with a glucose uptake assay, gallotannins were identified in the banaba extract as components responsible for the activity, not corosolic acid. Penta-O-galloyl-glucopyranose (PGG) was identified as the most potent gallotannin. A comparison of published data with results obtained for PGG indicates that PGG has a significantly higher glucose transport stimulatory activity than Lagerstroemin. Chen et al. have also shown that PGG exhibits anti-adipogenic properties in addition to stimulating the glucose uptake in adipocytes. The combination of glucose uptake and anti-adipogenesis activity is not found in the current insulin mimetic drugs and may indicate a great therapeutic potential of PGG
Spatial differencing for sample selection models with ‘site-specific’ unobserved local effects
This paper proposes an estimator which combines spatial differencing with a two-step sample selection estimator. We derive identification, estimation, and inference results from ‘site-specific’ unobserved effects. These effects operate at a spatial scale that cannot be captured by administrative borders. Therefore, we use spatial differencing. We show that under justifiable assumptions, the estimator is consistent and asymptotically normal. A Monte Carlo experiment illustrates the small sample properties of our estimator. We apply our procedure to the estimation of a female wage offer equation in the United States and the results show the relevance of spatial differencing to account for ‘site-specific’ unobserved effects
People, power and pollution: environmental and public interest aspects of electric power plant siting
Explanatory Note:
On March 16, 1971, the National Academy of Engineering convened the Forum of the Committee on Power Plant Siting (COPPS) in Washington, D.C. After two days of plenary sessions the members of the three main working groups met for three days to begin drafting their reports. Four of the authors of the present report (Borrelli, Easterling, Lees and Poppe) constituted the sub-group on Environmental Aspects of Siting of Working Group II-Systems Approach to Site Selection. Intensive discussions in Washington in this sub-group, and the subsequent exchange of draft sections by mail, convinced us that we should go far beyond our original assignment and probe into all aspects of power plant siting, especially the public interest factors. During a second intensive working session in Pasadena, California, on April 22 and 23, 1971, we were joined by Guy Pauker and Burton H. Klein, who also participated in the subsequent redrafting of the final report. We are grateful to the NAE-COPPS for stimulating our thinking on this important and difficult problem. However, the final report is solely our responsibility as individuals and the responsibility of the Caltech Environmental Quality Laboratory.
Lester Lees
Director, Environmental Quality Laborator
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