Cramer-Rao bounds in the estimation of time of arrival in fading channels

This paper computes the Cramer-Rao bounds for the time of arrival estimation in a multipath Rice and Rayleigh fading scenario, conditioned to the previous estimation of a set of propagation channels, since these channel estimates (correlation between received signal and the pilot sequence) are sufficient statistics in the estimation of delays. Furthermore, channel estimation is a constitutive block in receivers, so we can take advantage of this information to improve timing estimation by using time and space diversity. The received signal is modeled as coming from a scattering environment that disperses the signal both in space and time. Spatial scattering is modeled with a Gaussian distribution and temporal dispersion as an exponential random variable. The impact of the sampling rate, the roll-off factor, the spatial and temporal correlation among channel estimates, the number of channel estimates, and the use of multiple sensors in the antenna at the receiver is studied and related to the mobile subscriber positioning issue. To our knowledge, this model is the only one of its kind as a result of the relationship between the space-time diversity and the accuracy of the timing estimation.Peer ReviewedPostprint (published version

Space-Time diversity for NLOS mitigation in TDOA-based positioning systems

This paper studies the potential impact of using space-Time information in the mitigation of the Non-LineOf-Sight condition in mobile subscriber's positioning systems. First of all, this work discusses the positioning problem based on measures of Time Differences Of Arrival departing from a more exact characterization of the signal statistics and including some geometrical restrictions to achieve an improved accurate. Furthermore, a novel approach that integrates signal propagation characteristics to information provided by a suitable timing estimation model based on Cramer Rao Bound for a Rayleigh-fading channel, when antenna arrays are used at the receiver and when a set ofchannel vector estimates are available, has been introduced to study the positive benefits of space-Time diversity. These approaches are evaluated within a realistic simulation scenario.Peer ReviewedPostprint (published version

Hydrogen vs. Battery in the long-term operation. A comparative between energy management strategies for hybrid renewable microgrids

The growth of the world’s energy demand over recent decades in relation to energy intensity and demography is clear. At the same time, the use of renewable energy sources is pursued to address decarbonization targets, but the stochasticity of renewable energy systems produces an increasing need for management systems to supply such energy volume while guaranteeing, at the same time, the security and reliability of the microgrids. Locally distributed energy storage systems (ESS) may provide the capacity to temporarily decouple production and demand. In this sense, the most implemented ESS in local energy districts are small–medium-scale electrochemical batteries. However, hydrogen systems are viable for storing larger energy quantities thanks to its intrinsic high mass-energy density. To match generation, demand and storage, energy management systems (EMSs) become crucial. This paper compares two strategies for an energy management system based on hydrogen-priority vs. battery-priority for the operation of a hybrid renewable microgrid. The overall performance of the two mentioned strategies is compared in the long-term operation via a set of evaluation parameters defined by the unmet load, storage efficiency, operating hours and cumulative energy. The results show that the hydrogen-priority strategy allows the microgrid to be led towards island operation because it saves a higher amount of energy, while the battery-priority strategy reduces the energy efficiency in the storage round trip. The main contribution of this work lies in the demonstration that conventional EMS for microgrids’ operation based on battery-priority strategy should turn into hydrogen-priority to keep the reliability and independence of the microgrid in the long-term operation

A Violência no Local de Trabalho em Instituições de Saúde: Um Estudo Monocêntrico sobre Causas, Consequências e Estratégias de Prevenção

Introduction: Workplace violence is one of the main risk factors in the professional world. Healthcare workers are at higher risk when compared to other sectors. Our study aimed to characterize physical and verbal violence in a public hospital and to define occupational health prevention and surveillance strategies. Material and Methods: Single center observational cross-sectional study, carried amongst healthcare workers in a public hospital in Lisbon. A qualitative survey was carried out through six in-depth interviews. A quantitative survey was carried through questionnaires delivered to 32 workers. A significance level of 5% was accepted in the assessment of statistical differences. The Mann-Whitney test and the Fisher’s exact test were used to calculate p values. Results: The main results are: (1) 41 violence incidents were reported in the quantitative phase; (2) 5/21 [23.81%] victims notified the incident to the occupational health department; (3) 18/21 [85.71%] victims reported a permanent state of hypervigilance; (4) 22/28 [78.57%] participants self-reported poor or no familiarity with internal reporting procedures; (5) 24/28 [85.71%] participants believed it is possible to minimize workplace violence. Discussion: Workplace violence is favored by unrestricted access to working areas, absence of security guards and police officers or scarce intervention. The low notification rate contributes to organizational lack of action. The state of hypervigilance reported in our study reflects the negative effects of threatening occupational stressors on mental health. Conclusion: Our results show that workplace violence is a relevant risk factor that significantly impacts workers’ health in a noxious manner, deserving a tailored occupational health approach whose priority areas and strategies have been determined.Introdução: A violência no local de trabalho é um dos principais fatores de risco no mundo do trabalho. Os trabalhadores da saúde apresentam um risco superior. O nosso estudo teve como objetivo caracterizar a violência física e verbal num hospital público e definir estratégias de prevenção e vigilância em saúde ocupacional. Material e Métodos: Estudo observacional transversal monocêntrico, conduzido num hospital público em Lisboa com trabalhadores da saúde. Foi realizado um inquérito qualitativo com entrevistas em profundidade a seis trabalhadores e um inquérito quantitativo com questionários a 32 trabalhadores. Aceitou-se um nível de significância de 5% na avaliação das diferenças estatísticas. O teste de Mann-Whitney e o teste exato de Fisher foram usados para calcular os valores de p. Resultados: Os principais resultados são: (1) 41 episódios reportados na fase quantitativa; (2) 5/21 [23,81%] vítimas notificaram o incidente; (3) 18/21 [85.71%] vítimas reportaram estados de hipervigilância permanente; (4) 22/28 [78,57%] participantes não conheciam ou conheciam mal os procedimentos de notificação; (5) 24/28 [85,71%] consideravam possível minimizar o problema. Discussão: A violência é favorecida pelo acesso livre às zonas de trabalho, ausência de agentes de segurança e polícia ou falta da respetiva intervenção. A baixa notificação contribui para a ausência de medidas organizacionais. O estado de hipervigilância relatado reflete o efeito prejudicial da exposição a fontes de stress e ameaça. Conclusão: A violência no local de trabalho é um fator de risco relevante, com impacto negativo na saúde dos trabalhadores e merece uma abordagem individualizada no âmbito da saúde ocupacional, cujas áreas e estratégias prioritárias foram definidas neste estudo. Palavras-chave: Fatores de Risco Profissionais; Prevenção; Saúde Ocupacional; Trabalhadores da Saúde; Violência no Local de trabalho.info:eu-repo/semantics/publishedVersio

Role of appetitive phenotype trajectory groups on child body weight during a family-based treatment for children with overweight or obesity.

ObjectiveEmerging evidence suggests that individual appetitive traits may usefully explain patterns of weight loss in behavioral weight loss treatments for children. The objective of this study was to identify trajectories of child appetitive traits and the impact on child weight changes over time.MethodsSecondary data analyses of a randomized noninferiority trial conducted between 2011 and 2015 evaluated children's appetitive traits and weight loss. Children with overweight and obesity (mean age = 10.4; mean BMI z = 2.0; 67% girls; 32% Hispanic) and their parent (mean age = 42.9; mean BMI = 31.9; 87% women; 31% Hispanic) participated in weight loss programs and completed assessments at baseline, 3, 6,12, and 24 months. Repeated assessments of child appetitive traits, including satiety responsiveness, food responsiveness and emotional eating, were used to identify parsimonious grouping of change trajectories. Linear mixed-effects models were used to identify the impact of group trajectory on child BMIz change over time.ResultsOne hundred fifty children and their parent enrolled in the study. The three-group trajectory model was the most parsimonious and included a high satiety responsive group (HighSR; 47.4%), a high food responsive group (HighFR; 34.6%), and a high emotional eating group (HighEE; 18.0%). Children in all trajectories lost weight at approximately the same rate during treatment, however, only the HighSR group maintained their weight loss during follow-ups, while the HighFR and HighEE groups regained weight (adjusted p-value < 0.05).ConclusionsDistinct trajectories of child appetitive traits were associated with differential weight loss maintenance. Identified high-risk subgroups may suggest opportunities for targeted intervention and maintenance programs

Evaluation of the program ‘understanding and learning in the classroom’

We present the program “understanding and learning in the classroom” centered on the improvement of reading comprehension strategies. We present also an evaluation of this program

L’impacte de la cabra (Capra hircus) sobre el teix (Taxus baccata) a l’illa de Mallorca

[cat] El teix Taxus baccata a les Balears es troba únicament a la Serra de Tramuntana, està protegit com d’Especial Protecció i és objecte d’un Pla de Maneig executat per la Conselleria de Medi Ambient del Govern de les Illes Balears. La forta pressió de les cabres Capra hircus, incrementada els darrer decennis per l’abandonament de les finques i l’agricultura, és una amenaça que fa perillar el futur del teix. El present treball completa i revisa l’inventari de teixos naturals a la Serra i avalua el seu estat de conservació en funció del grau d’afectació per les cabres assilvestrades. Un 70% dels teixos silvestres pateixen impactes visibles provocats per les cabres. Tot i que la majoria de teixos es trobem empenyalats, la gran majoria (un 84%) pateix un grau d’afectació moderat; el 14% restant presenta una afectació greu, amb una clara amenaça per a la seva supervivència. Els teixos menys afectats són els més difícilment accessibles, i no hi ha cap opció de que puguin créixer amb normalitat a un lloc on arribin les cabres. Ara que ja no es talla ni es permeten les cremes descontrolades, el teix podria tenir unes poblacions més nombroses, tot i que les elevades temperatures estivals i la disminució de les precipitacions, com a conseqüència del canvi climàtic, podrien esdevenir un factor limitant. Avui, però, el principal factor limitant no natural que afecta les poblacions de teix a Mallorca és la pressió que exerceixen les cabres assilvestrades les quals, en molts de casos, poden arribar a provocar la mort dels exemplars.[eng] The yew Taxus baccata in the Balearic Islands is only in the Serra de Tramuntana. It is under Special Protection category and is object of a Management Plan executed by the Balearic Environmental Administration. The strong pressure of goats Capra hircus, increased over the last decades due to the abandonment of farms and agriculture, is a threat that endangers yews future. The present report completes and reviews the inventory of natural yews in the Serra and evaluates its state of conservation based on the degree of involvement by the wild goats. 70% of natural yews suffer visible impacts caused by goats. Although most yews are in cliffs, the vast majority (84%) suffers a moderate degree of threat; the remaining 14% have a serious affectation, with a clear threat to their survival. The least-affected yews are the most difficult to reach, and there is no option to grow normally on a goat's place. Now that neither the cutting of yew or the uncontrolled burning are not allowed, the yew tree could have larger populations, although the high summer temperatures and the decrease of the precipitations, as a consequence of the climate change, could become a limiting factor. Today, however, the main unnatural limiting factor affecting yew populations in Mallorca is the pressure exerted by feral goats which, in many cases, may cause the death of specimens