880 resultados para Feature extraction


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Social interactions are a very important component in people"s lives. Social network analysis has become a common technique used to model and quantify the properties of social interactions. In this paper, we propose an integrated framework to explore the characteristics of a social network extracted from multimodal dyadic interactions. For our study, we used a set of videos belonging to New York Times" Blogging Heads opinion blog. The Social Network is represented as an oriented graph, whose directed links are determined by the Influence Model. The links" weights are a measure of the"influence" a person has over the other. The states of the Influence Model encode automatically extracted audio/visual features from our videos using state-of-the art algorithms. Our results are reported in terms of accuracy of audio/visual data fusion for speaker segmentation and centrality measures used to characterize the extracted social network.

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Background: To evaluate the safety of immediate sequential bilateral cataract extraction (ISBCE) with respect to indications, visual outcomes, complications, benefits and disadvantages. Methods: This is a retrospective review of all ISBCEs performed at Kantonsspital Winterthur, Switzerland, between April 2000 and September 2013. The case notes of 500 eyes of 250 patients were reviewed. Of these 500 eyes, 472 (94.4%) had a straight forward phacoemulsification with posterior chamber intraocular lens implantation; 21 (4.2%) had a planned extracapsular cataract extraction; 4 (0.8%) had an intracapsular cataract extraction and 3 (0.6%) had a combined phacoemulsification with trabeculectomy. Results: Over 66% of eyes achieved improved visual acuity (at least 3 Snellen lines) following ISBCE. Median preoperative best corrected visual acuity (BCVA) was 0.5 LogMAR; the interquartile range was [0.4, 1] LogMAR. At one week control the median BCVA was 0.3 LogMAR, IQR [0.1, 0.5] LogMAR. At one month the median BCVA was 0.15 LogMAR, IQR [0.05, 0.3] (p < 0.01). There were no sight-threatening intraoperative or postoperative complications observed. Conclusions: ISBCE is an effective and safe option with high degree of patient satisfaction. The relative benefits of ISBCE should be balanced against the theoretically enhanced risks.

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In forensic investigation of firearm-related cases, determination of the residual amount of volatile compounds remaining inside a cartridge could be useful in estimating the time since its discharge. Published approaches are based on following the decrease of selected target compounds as a function of time by using solid phase micro-extraction (SPME). Naphthalene, as well as an unidentified decomposition product of nitrocellulose (referred to as "TEA2"), are usually employed for this purpose. However, reliability can be brought into question given their high volatility and the low reproducibility of their extracted quantities. In order to identify alternatives and therefore develop improved dating methods, an extensive study on the composition and variability of volatile residues in nine different types of cartridges was carried out. Analysis was performed using headspace sorptive extraction (HSSE), which is a more exhaustive technique compared to SPME. 166 compounds were identified (several of which for the first time), and it was observed that the final compositional characteristics of each residue were strongly dependent on its source. Variability of single identified compounds within and between different types of cartridge, as well as their evolution over time, was also studied. Many explosion products containing up to 4 aromatic rings were found to be globally present in high proportions amongst residues. 27 of them (excluding naphthalene) also presented detectable decreases during the first 24 h. Therefore, they could be used as complementary target analytes in future dating methods.

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ABSTRACT Functional genomic analyses require intact RNA; however, Passiflora edulis leaves are rich in secondary metabolites that interfere with RNA extraction primarily by promoting oxidative processes and by precipitating with nucleic acids. This study aimed to analyse three RNA extraction methods, Concert™ Plant RNA Reagent (Invitrogen, Carlsbad, CA, USA), TRIzol® Reagent (Invitrogen) and TRIzol® Reagent (Invitrogen)/ice -commercial products specifically designed to extract RNA, and to determine which method is the most effective for extracting RNA from the leaves of passion fruit plants. In contrast to the RNA extracted using the other 2 methods, the RNA extracted using TRIzol® Reagent (Invitrogen) did not have acceptable A260/A280 and A260/A230 ratios and did not have ideal concentrations. Agarose gel electrophoresis showed a strong DNA band for all of the Concert™ method extractions but not for the TRIzol® and TRIzol®/ice methods. The TRIzol® method resulted in smears during electrophoresis. Due to its low levels of DNA contamination, ideal A260/A280 and A260/A230 ratios and superior sample integrity, RNA from the TRIzol®/ice method was used for reverse transcription-polymerase chain reaction (RT-PCR), and the resulting amplicons were highly similar. We conclude that TRIzol®/ice is the preferred method for RNA extraction for P. edulis leaves.

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Diagnosis of community acquired legionella pneumonia (CALP) is currently performed by means of laboratory techniques which may delay diagnosis several hours. To determine whether ANN can categorize CALP and non-legionella community-acquired pneumonia (NLCAP) and be standard for use by clinicians, we prospectively studied 203 patients with community-acquired pneumonia (CAP) diagnosed by laboratory tests. Twenty one clinical and analytical variables were recorded to train a neural net with two classes (LCAP or NLCAP class). In this paper we deal with the problem of diagnosis, feature selection, and ranking of the features as a function of their classification importance, and the design of a classifier the criteria of maximizing the ROC (Receiving operating characteristics) area, which gives a good trade-off between true positives and false negatives. In order to guarantee the validity of the statistics; the train-validation-test databases were rotated by the jackknife technique, and a multistarting procedure was done in order to make the system insensitive to local maxima.

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Objective: The goal of the present retrospective study is to describe the distribution of the supernumerary teeth in a population of patients that have been attended at the Public Clinic of the Department of Oral Surgery. Background: Supernumerary teeth and multiple hyperdontia are usually associated with different syndromes, such as Gardner syndrome, or with facial fissures; however, they can appear in patients without any pathology. Their prevalence oscillates to 0.5-3.8% in patients with permanent teeth and to 0.35-0.6% in patients with primary teeth. Patients and Methods: A total of 36,057 clinical histories of patients that were admitted at the clinic between September of 1991 and March of 2003 were revised. The following data were extrapolated: age, sex, number of extracted supernumerary teeth, localization, morphology and type of supernumerary teeth. Consequently, 102 patients were included into the present study. Results: Of the 147 supernumerary teeth identified in the oral cavities of patients 145 were extracted. The most frequent supernumerary teeth identified were mesiodens (46.9%), followed by premolars (24.1%) and fourth molars or distal molars (18%). As for location, 74.5% of the supernumerary teeth were found in the superior maxillary bone and 46.9% of the supernumerary teeth were present in the palatine/lingual area. Heteromorphology was found in two thirds of the supernumerary teeth, with conical shape being the most frequent. Finally, 29.7% of the supernumerary teeth had occlusion with permanent teeth, and mesiodens were the predominating type of supernumerary teeth that showed this feature. Conclusions: Mesiodens very frequently cause retention of permanent incisors, which erupt spontaneously after the extraction of supernumerary teeth, if there is sufficient space in the dental arch and if they conserve the eruptive force. Generally, supernumerary premolars are eumorphic and are casually discovered during radiological exam, if not producing any symptomology.

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In this study we used market settlement prices of European call options on stock index futures to extract implied probability distribution function (PDF). The method used produces a PDF of returns of an underlying asset at expiration date from implied volatility smile. With this method, the assumption of lognormal distribution (Black-Scholes model) is tested. The market view of the asset price dynamics can then be used for various purposes (hedging, speculation). We used the so called smoothing approach for implied PDF extraction presented by Shimko (1993). In our analysis we obtained implied volatility smiles from index futures markets (S&P 500 and DAX indices) and standardized them. The method introduced by Breeden and Litzenberger (1978) was then used on PDF extraction. The results show significant deviations from the assumption of lognormal returns for S&P500 options while DAX options mostly fit the lognormal distribution. A deviant subjective view of PDF can be used to form a strategy as discussed in the last section.

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In fetal brain MRI, most of the high-resolution reconstruction algorithms rely on brain segmentation as a preprocessing step. Manual brain segmentation is however highly time-consuming and therefore not a realistic solution. In this work, we assess on a large dataset the performance of Multiple Atlas Fusion (MAF) strategies to automatically address this problem. Firstly, we show that MAF significantly increase the accuracy of brain segmentation as regards single-atlas strategy. Secondly, we show that MAF compares favorably with the most recent approach (Dice above 0.90). Finally, we show that MAF could in turn provide an enhancement in terms of reconstruction quality.

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Stochastic learning processes for a specific feature detector are studied. This technique is applied to nonsmooth multilayer neural networks requested to perform a discrimination task of order 3 based on the ssT-block¿ssC-block problem. Our system proves to be capable of achieving perfect generalization, after presenting finite numbers of examples, by undergoing a phase transition. The corresponding annealed theory, which involves the Ising model under external field, shows good agreement with Monte Carlo simulations.

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El treball Ressuscitant a Disney: Rastrejant el sempre present esperit de Walt Disney en els llargmetratges animats de l'era Michael Eisner (1984-2004) pretén definir i analitzar les característiques, tant respecte al procés creatiu com en la definició de contingut, integrades en els clàssics originals de Disney per, a continuació, demostrar que aquestes van ser recuperades i implementades de nou després de la mort de Walt Disney -amb lleus adaptacions- per donar lloc a una segona edat d'or de l'animació