A Semi-Supervised Approach for the Semantic Segmentation of Trajectories

A first fundamental step in the process of analyzing movement data is trajectory segmentation, i.e., splitting trajecto- ries into homogeneous segments based on some criteria. Although trajectory segmentation has been the object of several approaches in the last decade, a proposal based on a semi-supervised approach remains inexistent. A semi-supervised approach means that a user labels manually a small set of trajectories with meaningful segments and, from this set, the method infers in an unsupervised way the segments of the remaining trajecto- ries. The main advantage of this method compared to pure supervised ones is that it reduces the human effort to label the number of trajectories. In this work, we propose the use of the Minimum Description Length (MDL) principle to measure homogeneity inside segments. We also introduce the Reactive Greedy Randomized Adaptive Search Procedure for semantic Semi- supervised Trajectory Segmentation (RGRASP-SemTS) algorithm that segments trajectories by combining a limited user labeling phase with a low number of input parameters and no predefined segmenting criteria. The approach and the algorithm are pre- sented in detail throughout the paper, and the experiments are carried out on two real-world datasets. The evaluation tests prove how our approach outperforms state-of-the-art competitors when compared to ground truth. This is a preprint version of the full article published by IEEE at https://ieeexplore.ieee.org/document/841127

Funcionalidad física como indicador de disponibilidad de hábitat en Islas Marietas, Nayarit, México

Background. Few investigations use functional diversity and the reef functional index (IFA) to assess the sta-te of reef communities. Objectives. Evaluate physical functionality as an indicator of fish habitat availability and its relationship with functional diversity. Methods. The physical functionality of the reef was evaluated using the IFA, integrating data on coral cover, structural complexity, and calcification rate. The structure of the fish assemblages was analyzed by calculating functional diversity indices (richness, evenness, and divergen-ce) based on six functional traits (body size, mobility, activity period, type of aggregation, position in the water column, and diet). The relationship between functional diversity and IFA was evaluated using linear regression analysis. Results. Área de Restauración showed the highest values in the IFA; on the contrary, Túnel Amarra-dero presented the lowest values. In both sites, a greater presence of Pocillopora verrucosa was observed. Functional diversity presented the lowest values in the three functional indices in Área de Restauración. Linear regression analyses were not significant. Conclusions. No linear relationship was found between the IFA and functional diversity; this can be attributed to the fact that in sites with low coral cover, such as Islas Marietas, the functional diversity of fish presents a weak relationship with the three-dimensionality provided by corals since in sites with low coral cover, other structural elements (geologic features and rock substrates) could promote these three-dimensional structures.Antecedentes. Pocas investigaciones emplean la diversidad funcional y el Índice de Función Arrecifal (IFA) para evaluar el estado de las comunidades arrecifales. Objetivo. Evaluar la funcionalidad física como indica-dor de disponibilidad de hábitat de peces y su relación con la diversidad funcional. Métodos. La funcionalidad física del arrecife se evaluó mediante el IFA integrando datos de cobertura coralina, complejidad estructural y tasa de calcificación. La estructura de los ensamblajes de peces se analizó mediante el cálculo de índices de diversidad funcional (riqueza, equidad y divergencia) con base en seis atributos funcionales (tamaño corporal, movilidad, periodo de actividad, tipo de agregación, posición en la columna de agua y dieta). La relación entre la diversidad funcional del ensamblaje y el IFA se evaluó mediante un análisis de regresión lineal. Resultados. La Zona de Restauración presentó los valores más altos en el IFA; por el contrario, Túnel Amarradero presentó los valores másbajos. En ambos sitios se observó una mayor presencia de Pocillopora verrucosa. La diversidad funcional presentó los valores más bajos en los tres índices funcionales en la Zona de Restauración. Los análisis de regresión lineal no fueron significativos. Conclusiones. No se encontró una relación lineal entre el IFA y la diversidad funcional, esto puede atribuirse a que en sitios con baja cobertura coralina como Islas Marietas, la diversidad funcional de peces presenta una débil relación con la tridimen-sionalidad otorgada por los corales. Lo anterior debido a que, en sitios con baja cobertura coralina, otros elementos estructurales (características geológicas y sustratos rocosos) podrían proveer de esas estructuras tridimensionales

Dual and recombinant infections: an integral part of the HIV-1 epidemic in Brazil.

We systematically evaluated multiple and recombinant infections in an HIV-infected population selected for vaccine trials. Seventy-nine HIV-1 infected persons in a clinical cohort study in Rio de Janeiro, Brazil, were evaluated for 1 year. A combination of molecular screening assays and DNA sequencing showed 3 dual infections (3.8%), 6 recombinant infections (7.6%), and 70 (88.6%) infections involving single viral subtypes. In the three dual infections, we identified HIV-1 subtypes F and B, F and D, and B and D; in contrast, the single and recombinant infections involved only HIV-1 subtypes B and F. The recombinants had five distinct B/F mosaic patterns: Bgag-p17/Bgag-p24/Fpol/Benv, Fgag-p17/Bgag-p24/Fpol/Fenv, Bgag-p17/B-Fgag-p24/Fpol/Fenv, Bgag-p17/B-Fgag-p24/Fpol/Benv, and Fgag-p17/B-Fgag-p24/Fpol/Fenv. No association was found between dual or recombinant infections and demographic or clinical variables. These findings indicate that dual and recombinant infections are emerging as an integral part of the HIV/AIDS epidemic in Brazil and emphasize the heterogenous character of epidemics emerging in countries where multiple viral subtypes coexist

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Portuguese Guinea & the Liberation Movement

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