Estimator stability analysis in SLAM

IFAC Symposium on Intelligent Autonomous Vehicles (IAV), 2004, Lisboa (Portugal)This work presents an analysis of the state estimation error dynamics for a linear system within the Kalman filter based approach to Simultaneous Localization and Map Building. Our objective is to demonstrate that such dynamics is marginally stable. The paper also presents the necessary modifications required in the observation model, in order to guarantee zero mean stable error dynamics. Simulations for a one-dimensional robot and a planar vehicle are presented.This work was supported by the project 'Supervised learning of industrial scenes by means of an active vision equipped mobile robot.' (J-00063).Peer Reviewe

Stochastic State Estimation for Simultaneous Localization and Map Building in Mobile Robotics

En Cutting Edge Robotics, 223-242. Advanced Robotic Systems Press, 2005.The study of stochastic models for Simultaneous Localization and Map Building (SLAM) in mobile robotics has been an active research topic for over fifteen years. Within the Kalman filter (KF) approach to SLAM, seminal work (Smith and Cheeseman, 1986) suggested that as successive landmark observations take place, the correlation between the estimates of the location of such landmarks in a map grows continuously. This observation was later ratified (Dissanayake et al., 2001) with a proof showing that the estimated map converges monotonically to a relative map with zero uncertainty. They also showed how the absolute accuracy of the map reaches a lower bound defined only by the initial vehicle uncertainty, and proved it for a one-landmark vehicle with no process noise. From an estimation theoretic point of view, we address these results as a consequence of partial observability. We show that error free reconstruction of the map state vector is not possible with typical measurement models, regardless of the vehicle model chosen, and show experimentally that the expected error in state estimation is proportional to the number of landmarks used. Error free reconstruction is only possible once full observability is guaranteed.This work was supported by projects: 'Supervised learning of industrial scenes by means of an active vision equipped mobile robot.' (J-00063), 'Integration of robust perception, learning, and navigation systems in mobile robotics' (J-0929).Peer Reviewe

Biología molecular del carcinoma de tiroides de estirpe folicular (II). Aplicaciones clínicas

The great advance of molecular medicine over the last few years gives us an attractive vision of the new possibilities in diagnosis and therapeutics of thyroid cancer and helps us to understand its biological behaviour. The clinical application of the growing understanding of gene alterations involved in thyroidal oncogenesis is becoming a reality. Such knowledge might contribute to greater diagnostic accuracy, by helping us characterise malignant or benign cells, predict tumour outcome or state its origin. Likewise it might be useful to know the response to conventional therapies or the future implications of pharmacogenetics. In addition molecular medicine applications ought to be considered in determining the prognosis of spontaneous and familiar carcinomas. Such information can significantly improve current clinical-pathologic prognostic methods

Research at the learning and vision mobile robotics group 2004-2005

Spanish Congress on Informatics (CEDI), 2005, Granada (España)This article presents the current trends on wheeled mobile robotics being pursued at the Learning and Vision Mobile Robotics Group (IRI). It includes an overview of recent results produced in our group in a wide range of areas, including robot localization, color invariance, segmentation, tracking, audio processing and object learning and recognition.This work was supported by projects: 'Supervised learning of industrial scenes by means of an active vision equipped mobile robot.' (J-00063), 'Integration of robust perception, learning, and navigation systems in mobile robotics' (J-0929).Peer Reviewe

Biología molecular del carcinoma de tiroides de estirpe folicular. Bases moleculares en la oncogénesis tiroidea

Existen datos que nos permiten afirmar que probablemente, en gran parte de los casos, no existe una solución de continuidad entre las diferentes neoplasias tiroideas de estirpe folicular. Cabe pensar que el proceso evolutivo comienza con una serie de alteraciones moleculares que condicionan la aparición del adenoma folicular (AF). Cambios posteriores propiciarán el desarrollo de un carcinoma folicular (CF). La aparición del carcinoma papilar (CP) tiene probablemente un itinerario similar sin que esté demostrado que tenga su origen en AF. Ulteriores cambios genéticos, tanto en el CP como en el CF encaminarán hacia la indiferenciación celular y con ello el desarrollo del carcinoma indiferenciado (CI). Esta sucesión de alteraciones moleculares condiciona un empeoramiento en el pronóstico de la neoplasia tiroidea. Por ello, las neoplasias tiroideas constituyen un excelente modelo para el estudio de la cronología de los cambios moleculares que condicionan la evolución desde la benignidad a la malignidad. Se ha comprobado que en algunas neoplasias de tiroides existe inestabilidad genética que favorece dichos cambios moleculares. Como fenómeno inicial es frecuente observar alteraciones en los protooncogenes mientras que las mutaciones en los genes supresores de tumor suelen ser un evento tardío. La aparición de agresividad o invasividad de la neoplasia también se puede investigar mediante el estudio de cambios moleculares. La aplicación clínica de dichos hallazgos comienza a ser una realidad, lo que facilitará la precisión diagnóstica y con ello una terapéutica más eficaz.According to current data, it seems probable that there is no interruption in the evolution of different follicular thyroid neoplasm. Probably transforming events responsible for the transition from normal to tumor cells start with molecular changes that determine the appearance of follicular adenoma. Later changes propitiate the development of follicular cancer. It is likely that the generation of papillary carcinoma follows a different pathway without passing through a previous phase of follicular adenoma. Subsequently, genetic changes render the cell prone to a failure to differentiate, culminating in the development of anaplastic cancer. Those incidental molecular changes result in a dramatic worsening in the prognosis of thyroid cancer. Research into thyroid tumors is likely to be instructive in view of the spectrum they span, from benign adenomas to poorly differentiated carcinomas. It has been proven that molecular alterations in thyroid tumor cells are predisposed by genome instability. Usually changes of protooncogenes represent an early event whereas mutations of suppressant genes are usually a late phenomenon. The onset of aggressive or invasive behavior may be studied, and perhaps can be predicted in the future, by molecular changes. The clinical application of the growing understanding of gene alterations involved in thyroidal oncogenesis is becoming a reality. Such knowledge might contribute, in the near future, to greater diagnostic accuracy and effective treatment for thyroid malignancie

Bryophytes of Europe Traits (BET) dataset: a fundamental tool for ecological studies

Bryophytes are a diverse group of organisms with unique properties, yet they are severely underrepresented in plant trait databases. Building on the recently published European Red List of bryophytes and previous trait compilations, we present the Bryophytes of Europe Traits (BET) data set, including biological traits such as those related to life history, growth habit, sexual and vegetative reproduction; ecological traits such as indicator values, substrate and habitat; and bioclimatic variables based on the species' European range. The data set includes values for 65 traits and 25 bio-climatic variables, containing more than 135,000 trait values with a completeness of 82.7% on average. The data set will enable future studies in bryophyte biology, ecology and conservation, and may help to answer fundamental questions in bryology.info:eu-repo/semantics/publishedVersio

Genomic diversity of human papillomavirus-16, 18, 31, and 35 isolates in a Mexican population and relationship to European, African, and Native American variants

AbstractCervical cancer, mainly caused by infection with human papillomaviruses (HPVs), is a major public health problem in Mexico. During a study of the prevalence of HPV types in northeastern Mexico, we identified, as expected from worldwide comparisons, HPV-16, 18, 31, and 35 as highly prevalent. It is well known that the genomes of HPV types differ geographically because of evolution linked to ethnic groups separated in prehistoric times. As HPV intra-type variation results in pathogenic differences, we analyzed genomic sequences of Mexican variants of these four HPV types. Among 112 HPV-16 samples, 14 contained European and 98 American Indian (AA) variants. This ratio is unexpected as people of European ethnicity predominate in this part of Mexico. Among 15 HPV-18 samples, 13 contained European and 2 African variants, the latter possibly due to migration of Africans to the Caribbean coast of Mexico. We constructed phylogenetic trees of HPV-31 and 35 variants, which have never been studied. Forty-six HPV-31 isolates from Mexico, Europe, Africa, and the United States (US) contained a total of 35 nucleotide exchanges in a 428-bp segment, with maximal distances between any two variants of 16 bp (3.7%), similar to those between HPV-16 variants. The HPV-31 variants formed two branches, one apparently the European, the other one an African branch. The European branch contained 13 of 29 Mexican isolates, the African branch 16 Mexican isolates. These may represent the HPV-31 variants of American Indians, as a 55% prevalence of African variants in Mexico seems incomprehensible. Twenty-seven HPV-35 samples from Mexico, Europe, Africa, and the US contained 11 mutations in a 893-bp segment with maximal distances between any two variants of only 5 mutations (0.6%), including a characteristic 16-bp insertion/deletion. These HPV-35 variants formed several phylogenetic clusters rather than two- or three-branched trees as HPV-16, 18, and 31. An HPV-35 variant typical for American Indians was not identifiable. Our research suggests type specific patterns of evolution and spread of HPV-16, 18, 31, and 35 both before and after the worldwide migrations of the last four centuries. The high prevalence of highly carcinogenic HPV-16 AA variants, and the extensive diversity of HPV-18, 31, and 35 variants with unknown pathogenic properties raise the possibility that HPV intra-type variation contributes to the high cervical cancer burden in Mexico

Aplastic anemia and severe pancytopenia during treatment with peg-interferon, ribavirin and telaprevir for chronic hepatitis C

Telaprevir and Boceprevir are the first direct acting antivirals approved for chronic hepatitis C in combination with peg-interferon alfa and ribavirin. Pancytopenia due to myelotoxicity caused by these drugs may occur, but severe hematological abnormalities or aplastic anemia (AA) have not been described. We collected all cases of severe pancytopenia observed during triple therapy with telaprevir in four Spanish centers since approval of the drug in 2011. Among 142 cirrhotic patients receiving treatment, 7 cases of severe pancytopenia (5%) were identified and three were consistent with the diagnosis of AA. Mean age was 59 years, five patients had compensated cirrhosis and two patients had severe hepatitis C recurrence after liver transplantation. Severe pancytopenia was diagnosed a median of 10 wk after the initiation of therapy. Three patients had pre-treatment hematological abnormalities related to splenomegaly. In six patients, antiviral treatment was interrupted at the onset of hematological abnormalities. Two patients died due to septic complications and one patient due to acute alveolar hemorrhage. The remaining patients recovered. Severe pancytopenia and especially AA, are not rare during triple therapy with telaprevir in patients with advanced liver disease. Close monitoring is imperative in this setting to promptly detect serious hematological disorders and to prevent further complications

Late presentation of chronic HBV and HCV patients seeking first time specialist care in Spain: a 2-year registry review

Chronic viral hepatitis infection affects an estimated 325 million people globally. People who initiate treatment after significant disease progression face increased risk of severe liver complications and death. Data are scarce on the characteristics and risk factors of people who present late to care in Spain and globally. Data were collected from January 2018 to December 2019 to report late presentation (LP) to specialist care at 11 large university hospitals in Spain to assess related risk factors using a multivariable logistic regression model. 2290 (CHB = 505, CHC = 1785) patients were analysed, with 581 (25.2%) presenting late. Hepatitis C patients more frequently reported LP compared to hepatitis B patients (28.1% vs 15.0%; p < 0.001). Older age (p < 0.001), being male (p < 0.001), being Spanish-born (p < 0.001), and having an unknown origin of referral (p = 0.08) were associated with a higher likelihood of LP. Advanced liver disease was identified in 533 (23%) patients and late-stage liver disease in 124 (5.4%). LP, including with irreversible liver damage, to viral hepatitis specialist care is frequent in Spain, despite being a country with unrestricted treatment access. Initiatives to reduce LP should specifically target men, older individuals, foreign-born populations for CHB, and Spanish nationals for CHC.AP, TMW, JVL acknowledge support to ISGlobal from the Spanish Ministry of Science, Innovation and Universities through the “Centro de Excelencia Severo Ochoa 2019–2023” Programme (CEX2018-000806-S), and support from the Government of Catalonia through the CERCA Programme. CAP acknowledges support from the Secretaria d’Universitats i Recerca de la Generalitat de Catalunya and the European Social Fund as an AGAUR-funded PhD fellow

Trabecular bone score in active or former smokers with and without COPD

Background Smoking is a recognized risk factor for osteoporosis. Trabecular bone score (TBS) is a novel texture parameter to evaluate bone microarchitecture. TBS and their main determinants are unknown in active and former smokers. Objective To assess TBS in a population of active or former smokers with and without Chronic Obstructive Pulmonary Disease (COPD) and to determine its predictive factors. Methods Active and former smokers from a pulmonary clinic were invited to participate. Clinical features were recorded and bone turnover markers (BTMs) measured. Lung function, low dose chest Computed Tomography scans (LDCT), dual energy absorptiometry (DXA) scans were performed and TBS measured. Logistic regression analysis explored the relationship between measured parameters and TBS. Results One hundred and forty five patients were included in the analysis, 97 (67.8%) with COPD. TBS was lower in COPD patients (median 1.323; IQR: 0.13 vs 1.48; IQR: 0.16, p = 0.003). Regression analysis showed that a higher body mass index (BMI), younger age, less number of exacerbations and a higher forced expiratory volume-one second (FEV1%) was associated with better TBS (β = 0.005, 95% CI:0.000–0.011, p = 0.032; β = -0.003, 95% CI:-0.007(-)-0.000, p = 0.008; β = -0.019, 95% CI:-0.034(-)-0.004, p = 0.015; β = 0.001, 95% CI:0.000–0.002, p = 0.012 respectively). The same factors with similar results were found in COPD patients. Conclusions A significant proportion of active and former smokers with and without COPD have an affected TBS. BMI, age, number of exacerbations and the degree of airway obstruction predicts TBS values in smokers with and without COPD. This important information should be considered when evaluating smokers at risk of osteoporosis