Automatic visual dictionary generation through Optimum-Path Forest clustering

Image categorization by means of bag of visual words has received increasing attention by the image processing and vision communities in the last years. In these approaches, each image is represented by invariant points of interest which are mapped to a Hilbert Space representing a visual dictionary which aims at comprising the most discriminative features in a set of images. Notwithstanding, the main problem of such approaches is to find a compact and representative dictionary. Finding such representative dictionary automatically with no user intervention is an even more difficult task. In this paper, we propose a method to automatically find such dictionary by employing a recent developed graph-based clustering algorithm called Optimum-Path Forest, which does not make any assumption about the visual dictionary's size and is more efficient and effective than the state-of-the-art techniques used for dictionary generation. © 2012 IEEE.

Intrusion detection in computer networks using optimum-path forest clustering

Nowadays, organizations face the problem of keeping their information protected, available and trustworthy. In this context, machine learning techniques have also been extensively applied to this task. Since manual labeling is very expensive, several works attempt to handle intrusion detection with traditional clustering algorithms. In this paper, we introduce a new pattern recognition technique called Optimum-Path Forest (OPF) clustering to this task. Experiments on three public datasets have showed that OPF classifier may be a suitable tool to detect intrusions on computer networks, since it outperformed some state-of-the-art unsupervised techniques. © 2012 IEEE.

Conceptos y métodos de cálculo de la relación de precios del intercambio exterior = The concept of terms of trade and methods of computation

Incluye Bibliografía

A different concept of the private sector, a different concept of the public sector: notes for a Latin American debate

Presenta un analisis historico comparativo del proceso de modernizacion en America Latina y Europa y reflexiona sobre el debate entre lo publico y lo privado en los procesos de desarrollo economico de America Latina.

Economic performance clubs in the Americas: 1955-2003

Includes bibliography

Positional inconsistency: a new concept in social stratification

Includes bibliography

The concept of integration

Includes bibliography

The international division of industrial labour and the core-periphery concept

Includes bibliography

A prospective study on implants installed with flapless-guided surgery using the all-on-four concept in the mandible

Aim: Clinical data are scarce on flapless-guided surgery in the mandible using the all-on-four concept. In addition, limited documentation exists on the latter under immediate loading conditions with a pre-fabricated implant bridge. The aim was to provide detailed documentation focusing on clinical and radiographic outcome and complications. Material and methods: Sixteen systemically healthy non-smoking patients (10 women, 6 men, average age 59 years) with sufficient bone volume in the mandible were operated via flapless-guided surgery using the all-on-four concept. Clinical and radiographic data and complications were registered at 3, 6 and 12 months. Results: The overall implant survival rate was 90% with a trend for higher failure of short implants (P = 0.098). The mean bone level after 12 months of function was 0.83 mm with a maximum of 1.07 mm. Technical complications were common (15/16 patients). These mainly related to a misfit between the pre-fabricated prosthesis and abutment(s) (13/16 patients). Conclusion: If immediate loading of implants is pursued fabrication of the implant bridge should be based on actual impression of the implants at the time of surgery and not on their virtual position. © 2011 John Wiley & Sons A/S.

Introducing the biogeographic species pool

The species pool concept has played a central role in the development of ecological theory for at least 60 yr. Surprisingly, there is little consensus as to how one should define the species pool, and consequently, no systematic approach exists. Because the definition of the species pool is essential to infer the processes that shape ecological communities, there is a strong incentive to develop an ecologically realistic definition of the species pool based on repeatable and transparent analytical approaches. Recently, several methodological tools have become available to summarize repeated patterns in the geographic distribution of species, phylogenetic clades and taxonomically broad lineages. Here, we present three analytical approaches that can be used to define what we term 'the biogeographic species pool': distance-based clustering analysis, network modularity analysis, and assemblage dispersion fields. The biogeographic species pool defines the pool of potential community members in a broad sense and represents a first step towards a standardized definition of the species pool for the purpose of comparative ecological, evolutionary and biogeographic studies. © 2013 The Authors.

The platform switching concept revisited. An experimental study in dogs

Objective: To evaluate the influence of the configuration of the marginal aspect of implants placed immediately into extraction sockets on peri-implant hard tissue adaptation. Material and methods: In 6 Labrador dogs, endodontic treatments of the mesial roots of 1M1 were performed and the distal roots were removed. 2P2 was extracted as well. Implants were immediately placed in the center of the distal alveoli. Cylindrical straight implants were installed in the right side of the mandible (Control), while, in the left side, implants with a reduced diameter in the coronal portion, yielding an indentation in the surface continuity (Test), were installed. Cover screws were affixed, and the flaps were sutured to allow non-submerged healing. After 4 months of healing, histological slides were obtained for assessments. Results: A buccal resorption of 1.58 ± 1.28 and 1.90 ± 1.93 mm at the control and of 0.26 ± 0.90 and 0.14 ± 0.66 mm at the test sites was observed at the premolar and molar regions, respectively. The buccal coronal level of osseointegration was located apically to the margin of the smooth/rough surface border by 2.40 ± 0.90 and 3.70 ± 0.87 mm at the control sites and 1.19 ± 0.45 and 2.16 ± 0.96 mm at the test sites at the premolar and molar sites, respectively. All differences yielded statistical significance. Conclusions: The use of implants with a reduced diameter in their coronal aspect may contribute to preservation of the buccal bony crest in a more coronal level compared with conventional implants. Thus, the study confirmed the efficacy of the platform switching concept. © 2013 John Wiley & Sons A/S.

Metrics to support the evaluation of association rule clustering

Many topics related to association mining have received attention in the research community, especially the ones focused on the discovery of interesting knowledge. A promising approach, related to this topic, is the application of clustering in the pre-processing step to aid the user to find the relevant associative patterns of the domain. In this paper, we propose nine metrics to support the evaluation of this kind of approach. The metrics are important since they provide criteria to: (a) analyze the methodologies, (b) identify their positive and negative aspects, (c) carry out comparisons among them and, therefore, (d) help the users to select the most suitable solution for their problems. Some experiments were done in order to present how the metrics can be used and their usefulness. © 2013 Springer-Verlag GmbH.

Horizontal ridge augmentation of the atrophic anterior maxilla using rhBMP-2/ACS or autogenous bone grafts: A proof-of-concept randomized clinical trial

Aim To compare the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge carrier (ACS) with autogenous bone graft for augmentation of the edentulous atrophic anterior maxilla. Methods Twenty-four subjects were enrolled in a randomized, controlled, parallel-group, open-label clinical trial. Subjects either received rhBMP-2/ACS (1.5 mg/ml) or particulated autogenous bone harvested from the mandibular retromolar region. A titanium-mesh was used to provide space and wound stability. A guide was used to standardize clinical recordings using an analogue caliper. Alveolar ridge width was also assessed using cone-beam computed tomography. Results rhBMP-2/ACS yielded significantly greater radiographic horizontal bone gain compared with autogenous bone graft at immediate subcrestal levels (1.5 ± 0.7 versus 0.5 ± 0.9 mm; p = 0.01); non-significant differences were observed at mid- (2.9 ± 0.8 versus 2.9 ± 0.9 mm; p = 0.98) and apical (1.7 ± 0.9 versus 1.8 ± 1.1 mm; p = 0.85) crestal levels. No significant differences in clinical horizontal bone gain were observed at 6 months between rhBMP-2/ACS and autogenous bone graft (3.2 ± 0.9 mm versus 3.7 ± 1.4 mm; p = 0.31). Sixty-two implants were placed after 6 month of healing with no significant differences between groups for number of implants, implant size, primary stability and survival. Conclusions rhBMP-2/ACS appears a realistic alternative for augmentation of the edentulous atrophic anterior maxilla. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Poverty in the human development perspective: concept and measurement

Includes bibliography

Equivalence scales: a brief review of concept and methods

Includes bibliography