Papers by Carlos Andrés Nuñez Perez
Proceedings of the Seventh Annual Workshop on Cyber Security and Information Intelligence Research
In this paper we present an evolutionary multi-agent approach for anomaly detection based on adap... more In this paper we present an evolutionary multi-agent approach for anomaly detection based on adaptive clustering and classification. An evolutionary algorithm is proposed to allow agents to self-organize and cluster the data using different subsets of attributes, and dynamically created metaattributes. A performance metric is defined to allow the best agents to be reinforced and evolve, and to progressively eliminate ineffective agents. Our preliminary results show how the proposed approach can be used in isolation for intrusion detection, or in combination with other mechanisms to improve the performance and capabilities of intrusion, and anomaly detection systems Categories and Subject Descriptors D.4.6 [Security and Protection]: Unauthorized access
Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2012
In this paper we present a tactical defense infrastructure for mission survivability based on thr... more In this paper we present a tactical defense infrastructure for mission survivability based on three core inspirations from biological systems: multi-potentiation, feedback mechanisms, and redundancy. In tactical operational environments, these concepts may be realized through a combination of capabilities that include (1) dynamic allocation of resources for mission execution, (2) detection and identification of attacks and their effects, and (3) information sharing for system adaptation. As a proof-of-concept we introduce an extensible, multi-layer defense infrastructure inspired in the self-organization and resilience properties of biological systems. Two defense strategies are considered to validate the proposed model: a fast response consisting on rebooting a compromised system from a reference system image; and a slower response involving a process of identification of the attack, which then allows the node to change its base configuration and reboot to a state that is potentially immune to the same attack. Our experimental results show that the second strategy improves the overall resilience of the system for ongoing attacks after an initial exposure phase.
Kybernetika, 2015
Institute of Mathematics of the Czech Academy of Sciences provides access to digitized documents ... more Institute of Mathematics of the Czech Academy of Sciences provides access to digitized documents strictly for personal use. Each copy of any part of this document must contain these Terms of use.
Informatics in Control, Automation and Robotics II
The new contribution of this paper is the definition of the visual navigation as a global visual ... more The new contribution of this paper is the definition of the visual navigation as a global visual control task which implies continuity problems produced by the changes of visibility of image features during the navigation. A new smooth task function is proposed and a continuous control law is obtained by imposing the exponential decrease of this task function to zero. Finally, the visual servoing techniques used to carry out the navigation are the image-based and the intrinsic-free approaches. Both are independent of calibration errors which is very useful since it is so difficult to get a good calibration in this kind of systems. Also, the second technique allows us to control the camera in spite of the variation of its intrinsic parameters. So, it is possible to modify the zoom of the camera, for instance to get more details, and drive the camera to its reference position at the same time. An exhaustive number of experiments using virtual reality worlds to simulate a typical indoor environment have been carried out.
2008 37th International Conference on Parallel Processing, 2008
Crowd simulation can be considered as a special case of Virtual Environments where avatars are in... more Crowd simulation can be considered as a special case of Virtual Environments where avatars are intelligent agents instead of user-driven entities. These applications require both rendering visually plausible images of the virtual world and managing the behavior of autonomous agents. Although several proposals have focused on the software architectures for these systems, the scalability of crowd simulation is still an open issue. In this paper, we propose a scalable architecture that can manage large crowds of autonomous agents at interactive rates. This proposal consists of enhancing a previously proposed architecture through the efficient parallelization of the Action Server and the distribution of the semantic database. In this way, the system bottleneck is removed, and new Action Servers (hosted each one on a new computer) can be added as necessary. The evaluation results show that the proposed architecture is able to fully exploit the underlying hardware platform, regardless of both the number and the kind of computers that form the system. Therefore, this system architecture provides the scalability required for large-scale crowd simulation.
Lecture Notes in Computer Science, 2007
The world population is rapidly aging in industrialized countries and at a growing rate. As well ... more The world population is rapidly aging in industrialized countries and at a growing rate. As well as the percentage of elderly people is constantly increasing, so related health costs are augmenting, demanding novel technological solutions that both, enhance elder daily life independence and reduce the social and economic overhead of their hospitalization. The general framework of the presented work is about technological platforms for helping elder and handicapped people in a non-intrusive manner. The research in human motion ...
2010 - MILCOM 2010 MILITARY COMMUNICATIONS CONFERENCE, 2010
The Cognitive Network Management System (CNMS) is a joint research initiative between Rockwell Co... more The Cognitive Network Management System (CNMS) is a joint research initiative between Rockwell Collins and the Institute for Human Machine Cognition that aims to provide automated, policy-based real time network management for complex MANET networks. CNMS is a lightweight and efficient policy management framework designed to mitigate the need for centralized network management, reduce operator hands-on time, and increase network reliability. CNMS provides the necessary reasoning and enforcement mechanisms for the on-demand management of network topology and communication resources. Furthermore, it supports fully distributed policy learning mechanisms that enable networked devices to adapt at run-time to unanticipated network conditions and application requirements by creating and distributing learned policies. In this paper we describe the CNMS architecture and functionality. We focus our discussions on the CNMS architecture and policy learning mechanisms. Policy learning in CNMS is intrinsically distributed, and based on network performance observations for the refinement of contexts, and actions. In this paper we describe two examples for policy adaptation, one based on link capacity monitoring, and one based on adaptive frequency hoping strategies for interference mitigation. We then present some results from NS-3 evaluations of these two examples. CNMS has been implemented and tested in a two channel wireless testbed using the Universal Software Radio Peripheral (USRP) [1] and 802.11 wireless networking communication. We briefly discuss the testbed and describe some of our experimental results followed by a brief discussion of our findings, and recommendations for future work.
2009 International Conference on Ultra Modern Telecommunications & Workshops, 2009
This paper describes a dynamic gateway selection algorithm for cross-domain routing. The proposed... more This paper describes a dynamic gateway selection algorithm for cross-domain routing. The proposed cross-layer algorithm is designed on top of the XLayer communications substrate. In the context of this work, cross-domain routing refers to seamlessly routing across different networks running different routing algorithms without pre-defined gateways or a common underlaying protocol. We first provide a brief introduction of the XLayer communications substrate and the adaptive routing controller. After describing the algorithm and a summary of the proposed architecture, a proof-of-concept implementation is evaluated for a simple scenario developed in NS-2. Our preliminary results are encouraging and show the potential of our proposed strategy for dynamic gateway selection and crossdomain routing.
Energy Systems, 2012
In this paper, we describe a reinforcement learning-based approach to power management in smart g... more In this paper, we describe a reinforcement learning-based approach to power management in smart grids. The scenarios we consider are smart grid settings where renewable power sources (e.g. Photovoltaic panels) have unpredictable variations in power output due, for example, to weather or cloud transient effects. Our approach builds on a multi-agent system (MAS)-based infrastructure for the monitoring and coordination of smart grid environments with renewable power sources and configurable energy storage devices (battery banks). Software agents are responsible for tracking and reporting power flow variations at different points in the grid, and to optimally coordinate the engagement of battery banks (i.e. charge/idle/discharge modes) to maintain energy requirements to end-users. Agents are able to share information and coordinate control actions through a parallel communications infrastructure, and are also capable of learning, from experience, how to improve their response strategies for different operational conditions. In this paper we describe our approach and address some of the challenges associated with the communications infrastructure for distributed coordination. We also present some preliminary results of our first simulations using the GridLAB-D simulation environment, created by the US Department of Energy (DoE) at Pacific Northwest National Laboratory (PNNL).
Psychoneuroendocrinology, 2000
The present study analyzes if estradiol benzoate and/or progesterone interact with desmethylimipr... more The present study analyzes if estradiol benzoate and/or progesterone interact with desmethylimipramine (DMI) to diminish experimental anxiety. The animal model of anxiety used was the conditioned defensive burying test. Dose response curves for DMI (0.625, 1.25 and 2.5 mg/kg, every 24 h, during 21 days), estradiol benzoate (0.5, 1.0, 2.0 and 4.0 mg/rat, 48 h) and progesterone (0.5, 1.0 and 2.0 mg/rat,-4 h) were made in ovariectomized rats. DMI per se decreased dose dependently the cumulative burying time, an effect considered as anxiolytic-like. Progesterone produced a decrease in burying at the highest dose, while estradiol benzoate had no effect on defensive burying. Both, progesterone (0.5 mg/rat) and estradiol benzoate (4.0 mg/rat) were able to decrease the cumulative burying behavior when injected with a subthreshold dose of DMI (1.25 mg/kg). In addition, the effect of DMI (1.25 mg/kg) plus the combination of estradiol benzoate and progesterone, sequentially administered (48 h and 4 h before the tests, respectively), also produced a synergistic decrease in burying behavior. In general, the treatments produced no changes in burying behavior latency, neither in spontaneous ambulation or in nociception. It is concluded that DMI synergizes its anxiolytic-like effect when administered with estradiol alone or in combination with progesterone. Present data provide experimental evidence suggesting an interaction between hormones and antidepressants. Results are discussed on the basis of the interaction
Michigan Mathematical Journal, 2001
Seminars in Surgical Oncology, 1999
Neuroblastoma is one of the most intensely studied solid malignancies that affect the pediatric a... more Neuroblastoma is one of the most intensely studied solid malignancies that affect the pediatric age groups; its clinical presentation, treatment strategies and ultimate prognosis vary greatly. The biologic and genetic character of each tumor has an important impact on disease behavior, and clinical staging now incorporates these factors to generate an overall therapy plan. The clinical presentation of neuroblastoma is related to primary tumor location, production of metabolically active substances, and the presence of metastatic disease. There are also prognostically important associated syndromes including opsoclonus-myoclonus, Horner's syndrome, neurofibromatosis, and a variety of other neurocristopathies. The histologic features of the tumor are of prognostic significance and are utilized in treatment stratification. The International Neuroblastoma Staging System (INSS) has unified classic clinical staging. Features at diagnosis and those determined by initial operation are combined with biologic prognostic factors to achieve risk group assignment for virtually all patients. There are groups of children in which limited therapy is curative and intermediate-risk situations where standard multimodality treatment provides favorable outcomes. Unfortunately, there are many patients with high-risk disease that require intensive strategies, but success is still limited. It is in these most resistant patients that innovative approaches are being undertaken and novel strategies are being investigated.
Journal of Neurosurgery, 1988
✓ The clinical, radiological, and histopathological features of 21 cases of angiographically occu... more ✓ The clinical, radiological, and histopathological features of 21 cases of angiographically occult intracranial vascular malformations (AOIVM's) are analyzed, and a review of 241 additional appropriately documented, histologically verified cases collected from the literature is presented. In all, there were 115 (43.8%) arteriovenous malformations, 82 (31.2%) cavernous angiomas, 26 (9.9%) venous angiomas, 10 (3.8%) cases of capillary telangiectasis, and 29 (11%) mixed or unclassified angiomas. The result of the analysis shows that there are no essential differences in the patterns of clinical presentation, the computerized tomography (CT) appearance, or the surgical prognosis among these pathological types of vascular malformations. Certain histological features common to all AOIVM's (such as the small caliber, the more or less complete thrombosis of the malformed vessels, and the changes induced in the surrounding brain tissue by repeated microhemorrhages) seem to determine...
Journal of Molecular Graphics and Modelling, 1997
We have used a published set of inhibitors of HIV-1 protease 1 to build a COMBINE-type structure-... more We have used a published set of inhibitors of HIV-1 protease 1 to build a COMBINE-type structure-based QSAR model with good predictive ability (r 2 ϭ 0.90, q 2 ϭ 0.69). 2 Since the compounds in the training series exhibit most of their structural variability on one-half of the pseudosymmetrical binding cavity and only one binding orientation was explored for each molecule, the model describes mainly the effect of the structural changes on interactions involving only one-half of the binding cavity (pockets S1Ј and S2Ј). Thus, the model cannot be expected to give accurate predictions for new compounds exhibiting structural variation in both halves. The model does in fact show a tendency to underpredict slightly the biological activity of the molecules in the external test set. In an attempt to improve the quality of the model, both possible orientations of the ligands are now considered so that structural variation takes place in all binding pockets. One possibility would have been to build an additional set of complexes with the inhibitors docked in a reversed orientation. The alternative we have explored, however, consists of manipulating the data matrix describing the interaction energies so that each row is duplicated and the order of the variables in the duplicated rows is swapped between subunits. This simple approach has produced a new model that is similar in quality to the original model (r 2 ϭ 0.89, q 2 ϭ 0.64) but lacks the tendency to underpredict the activity of the compounds in the external set. Moreover, since equivalent residues are assigned equivalent weights, the model is insensitive to ligand orientation and is easier to interpret.
Journal of Medicinal Chemistry, 2001
International Journal of Radiation Oncology*Biology*Physics, 1982
One hundred forty-seven patients with non-inflammatory, Stage III and IV cancer were treated with... more One hundred forty-seven patients with non-inflammatory, Stage III and IV cancer were treated with irradiation alone (54 patients) or with a combination of irradiation and mastectomy (93 patients). In the T3 category, the local failure rate was 45% (5/11) for the irradiation alone patients vs 12% (3/25 for the irradiation plus surgery patients; in the T4 category these figures were 65% (28/43) vs 13% (9/68), respectively. Corresponding local failure rates by size of primary tumor were 50% (2/4) vs 15% (5/29 for tumors 0-5 cm, 43% (9/21) vs 14% (6/45) for 5-8 cm tumors, and 75% (22/29) vs 5% (1/20 for tumors greater than or equal to 8 cm. The rates of regional failure for the two treatment methods were compared according to N stage; they were 9% (2/23) for irradiation alone vs 11% (8/76) for irradiation plus surgery in the N0-1 category, and 58% (18/31) vs 18% (3/17), respectively, for the N2-3 category. A dose response analysis for patients with tumors greater than 5 cm treated with irradiation alone did not show a decrease in local failure rate with increasing total tumor dose over a range of 4000 to 7000 rad, suggesting that doses in this range are too low for these large tumors. Since a significant late complication rate has been reported with doses higher than this, patients with non-inflammatory, but large (greater than 5 cm) tumors, should be treated with a combination of surgery and irradiation whenever possible to achieve maximum local-regional control with a minimum probability of complications. In 36 patients with inflammatory carcinoma, the rates of local and regional failure were 52% (15/29) and 38% (11/29), respectively, for patients treated with irradiation alone, and 14% (1/7) and 29% (2/7), respectively, for patients receiving irradiation plus surgery. Since none of these differences were statistically significant, one cannot conclude that surgery should necessarily play a role in the treatment of inflammatory carcinoma.
International Journal of Radiation Oncology*Biology*Physics, 1993
Purpose: On-line radiotherapy imaging systems provide data that allow us to study the geometric n... more Purpose: On-line radiotherapy imaging systems provide data that allow us to study the geometric nature of treatment sn. It is more clinically relevant to examine the resultant dosimetric variation. In this work, daily beam position as recorded by the on-line images is used to recalculate the treatment plan to show the effect geometric variation has on dose. Methods and Materials: Daily 6 MV or 18 MV x-ray portal images were acquired using a fiberoptic on-line imaging system for 12 patients with cancers in the head and neck, thoracic, and pelvic regions. Each daily on-line portal image was aligned with the prescription simulation image using a template of anatomical structures defined on the latter. The outline of the actual block position was then superimposed on the prescription image. Daily block positions were cumulated to give a summary image represented by the block overlap isofrequency distribution. The summary data were used to analyze the amount of geometric variation relative to the prescription boundary on a histogram distribution plot. Treatment plans were recalculated by considering each aligned portal image as an individual beam. Results: On-Line Image Verification (OLIV) data can differentiate between systematic and random errors in a course of daily radiation therapy. The data emphasize that the type and magnitude of patient setup errors are unique for individual patients and different clinical situations. Head and neck sites had the least random variation (average O-100% block overlap isofrequency distribution width = 7 mm) compared to thoracic (average O-100% block overlap isofrequency distribution width = 12 mm) or pelvic sites (average O-100% block overlap isofrequency distribution width = 14 mm). When treatment delivery is analyzed case by case, systematic as well as random errors are represented. When the data are pooled by anatomical site, individuality of variations is lost and variation appears random. Recalculated plans demonstrated dosimetric deviations from the original plans. The differences between the two dosimetric distributions were emphasized using a technique of plan subtraction. This allowed quick identification of relative "hot and cold spots" in the recalculated plans. The magnitude and clinical significance of dosimetric variation was unique for each patient. Conclusions: OLIV data are useful to study geometric uncertainties because of the unique nature for individual patients. Dose recalculation is helpful to illustrate the dosimetric consequences of setup errors.
International Journal of Computers in Healthcare, 2010
Functional magnetic resonance imaging (fMRI) data have been used for identifying brain regions th... more Functional magnetic resonance imaging (fMRI) data have been used for identifying brain regions that activate when a subject is presented a stimulus or performs a task. Beyond identifying which regions of the brain are active during a task, it is also of interest to discover causal relationships among activity in those regions, that is, which regions of the brain influence, which other regions of the brain during a task. Two algorithms for causal discovery were applied to fMRI data, the greedy equivalence search (GES) algorithm and the independent multiple-sample greedy equivalence search (iMAGES). GES applies to individual datasets, and iMAGES to multiple datasets. We consider the stability of the GES results across subjects and experimental repetitions with the same subject. We find that some iMAGES connections agree with previous knowledge of the functional roles of the brain regions. The strengths and limitations of the research work and opportunities for future work are also discussed.
Human Reproduction, 1997
The aim of this study was to analyse if FSH male therapy causes an increase in the pregnancy rate... more The aim of this study was to analyse if FSH male therapy causes an increase in the pregnancy rate in IUI.
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Papers by Carlos Andrés Nuñez Perez