Reasoning and planning in dynamic domains: An experiment with a mobile robot

Progress made toward having an autonomous mobile robot reason and plan complex tasks in real-world environments is described. To cope with the dynamic and uncertain nature of the world, researchers use a highly reactive system to which is attributed attitudes of belief, desire, and intention. Because these attitudes are explicitly represented, they can be manipulated and reasoned about, resulting in complex goal-directed and reflective behaviors. Unlike most planning systems, the plans or intentions formed by the system need only be partly elaborated before it decides to act. This allows the system to avoid overly strong expectations about the environment, overly constrained plans of action, and other forms of over-commitment common to previous planners. In addition, the system is continuously reactive and has the ability to change its goals and intentions as situations warrant. Thus, while the system architecture allows for reasoning about means and ends in much the same way as traditional planners, it also posseses the reactivity required for survival in complex real-world domains. The system was tested using SRI's autonomous robot (Flakey) in a scenario involving navigation and the performance of an emergency task in a space station scenario

Saúde Brasil 2011 : uma análise da situação de saúde e a vigilância da saúde da mulher

Introdução: No Brasil, ocorrem cerca de 3 milhões de nascimentos ao ano, sendo grande parte deles por meio de cesarianas. Entender como se distribui esse procedimento no País é relevante para a reflexão sobre o papel das políticas públicas nesse contexto. Objetivos: a) Descrever: magnitude e tendência da taxa de cesáreas*1 no País; morbimortalidade materna e neonatal associada a tipo de parto; e características dos hospitais; b) analisar o preenchimento das variáveis da nova versão da Declaração de Nascido Vivo (DNV) que permitirão monitoramento das indicações de cesárea; c) descrever as respostas institucionais para o enfrentamento do problema. Métodos: Estudo descritivo de série histórica da taxa de cesarianas, no País e macrorregiões, segundo características sociodemográficas, morbimortalidade e tipo de provedor, com fonte em bancos de dados oficiais. Analisou-se a completitude de variáveis da versão da DNV de 2010 para monitoramento das indicações de cirurgia. Foram pesquisados documentos oficiais, visando identificar iniciativas para qualificar a atenção a partos e nascimentos e reduzir cesarianas desnecessárias. Resultados: A taxa de cesarianas foi de 32%, em 1994, e de 52%, em 2010, sendo menor no Norte e Nordeste. Mulheres submetidas a cesáreas tiveram 3,5 vezes mais probabilidade de morrer (entre 1992–2010) e 5 vezes mais de ter infecção puerperal (entre 2000–2011) que as de parto normal. No período, a proporção de prematuros se elevou, mais nas cesáreas (7,8%, sendo 6,4% nos partos normais em 2010). Em 2010, hospitais não públicos apresentaram taxas maiores (63,6%) e maior aumento no período de 2006 a 2010 (14,0%); para os públicos, as taxas foram de 47,8% (federais), de 39,6% (estaduais) e de 34,0% (municipais). Conclusão: A cesariana é frequente e sua proporção ascende no País, sendo muito elevada no setor de Saúde Suplementar. Para reverter essa tendência, serão necessárias várias medidas, incluindo a qualificação da informação para monitorar a efetividade das medidas propostas

The impact of childhood cancer on parents' socio-economic situation-A systematic review.

OBJECTIVE: Taking care of children diagnosed with cancer may have considerable consequences on parents' socio-economic situation. Our systematic review aimed to evaluate and synthesise the evidence on the impact of childhood cancer on parents' socio-economic situation. METHODS: Systematic literature searches for articles published between January 2000 and January 2019 were performed in PubMed, Scopus, and PsycINFO. Findings of eligible articles were narratively synthesised and quality appraised. RESULTS: Our systematic review included 35 eligible articles. Childhood cancer had a substantial impact on parents' socio-economic situation across all studies. This impact varied largely by geographical region. We observed a high prevalence of disruptions in parental employment such as job quitting or job loss, particularly among mothers. The associated income losses further contributed to families' perceived financial burden in addition to increased cancer-related expenses. Adverse socio-economic consequences were most pronounced shortly after diagnosis, however, persisted into early survivorship for certain groups of parents. We identified families of children diagnosed with haematological cancers, younger age at diagnosis, and lower parental socio-economic position to be at particular risk for adverse socio-economic consequences. CONCLUSIONS: Following the child's cancer diagnosis, parents experience a broad range of adverse socio-economic consequences. Further effort is needed to systematically implement an assessment of financial hardship in paediatric oncology together with appropriate support services along the cancer trajectory

Motoneuron membrane potentials follow a time inhomogeneous jump diffusion process

Stochastic leaky integrate-and-fire models are popular due to their simplicity and statistical tractability. They have been widely applied to gain understanding of the underlying mechanisms for spike timing in neurons, and have served as building blocks for more elaborate models. Especially the Ornstein–Uhlenbeck process is popular to describe the stochastic fluctuations in the membrane potential of a neuron, but also other models like the square-root model or models with a non-linear drift are sometimes applied. Data that can be described by such models have to be stationary and thus, the simple models can only be applied over short time windows. However, experimental data show varying time constants, state dependent noise, a graded firing threshold and time-inhomogeneous input. In the present study we build a jump diffusion model that incorporates these features, and introduce a firing mechanism with a state dependent intensity. In addition, we suggest statistical methods to estimate all unknown quantities and apply these to analyze turtle motoneuron membrane potentials. Finally, simulated and real data are compared and discussed. We find that a square-root diffusion describes the data much better than an Ornstein–Uhlenbeck process with constant diffusion coefficient. Further, the membrane time constant decreases with increasing depolarization, as expected from the increase in synaptic conductance. The network activity, which the neuron is exposed to, can be reasonably estimated to be a threshold version of the nerve output from the network. Moreover, the spiking characteristics are well described by a Poisson spike train with an intensity depending exponentially on the membrane potential

Trends in the Population Prevalence of People Who Inject Drugs in US Metropolitan Areas 1992–2007

Background: People who inject drugs (PWID) have increased risk of morbidity and mortality. We update and present estimates and trends of the prevalence of current PWID and PWID subpopulations in 96 US metropolitan statistical areas (MSAs) for 1992–2007. Current estimates of PWID and PWID subpopulations will help target services and help to understand long-term health trends among PWID populations. Methodology: We calculated the number of PWID in the US annually from 1992–2007 and apportioned estimates to MSAs using multiplier methods. We used four types of data indicating drug injection to allocate national annual totals to MSAs, creating four distinct series of component estimates of PWID in each MSA and year. The four component estimates are averaged to create the best estimate of PWID for each MSA and year. We estimated PWID prevalence rates for three subpopulations defined by gender, age, and race/ethnicity. We evaluated trends using multi-level polynomial models. Results: PWID per 10,000 persons aged 15–64 years varied across MSAs from 31 to 345 in 1992 (median 104.4) to 34 to 324 in 2007 (median 91.5). Trend analysis indicates that this rate declined during the early period and then was relatively stable in 2002–2007. Overall prevalence rates for non-Hispanic black PWID increased in 2005 as compared to other racial/ethnic groups. Hispanic prevalence, in contrast, declined across time. Importantly, results show a worrisome trend in young PWID prevalence since HAART was initiated – the mean prevalence was 90 to 100 per 10,000 youth in 1992–1996, but increased to >120 PWID per 10,000 youth in 2006–2007. Conclusions: Overall, PWID rates remained constant since 2002, but increased for two subpopulations: non-Hispanic black PWID and young PWID. Estimates of PWID are important for planning and evaluating public health programs to reduce harm among PWID and for understanding related trends in social and health outcomes

Estimating Design Effect and Calculating Sample Size for Respondent-Driven Sampling Studies of Injection Drug Users in the United States

Respondent-driven sampling (RDS) has become increasingly popular for sampling hidden populations, including injecting drug users (IDU). However, RDS data are unique and require specialized analysis techniques, many of which remain underdeveloped. RDS sample size estimation requires knowing design effect (DE), which can only be calculated post hoc. Few studies have analyzed RDS DE using real world empirical data. We analyze estimated DE from 43 samples of IDU collected using a standardized protocol. We find the previous recommendation that sample size be at least doubled, consistent with DE = 2, underestimates true DE and recommend researchers use DE = 4 as an alternate estimate when calculating sample size. A formula for calculating sample size for RDS studies among IDU is presented. Researchers faced with limited resources may wish to accept slightly higher standard errors to keep sample size requirements low. Our results highlight dangers of ignoring sampling design in analysis

Variability Measures of Positive Random Variables

During the stationary part of neuronal spiking response, the stimulus can be encoded in the firing rate, but also in the statistical structure of the interspike intervals. We propose and discuss two information-based measures of statistical dispersion of the interspike interval distribution, the entropy-based dispersion and Fisher information-based dispersion. The measures are compared with the frequently used concept of standard deviation. It is shown, that standard deviation is not well suited to quantify some aspects of dispersion that are often expected intuitively, such as the degree of randomness. The proposed dispersion measures are not entirely independent, although each describes the interspike intervals from a different point of view. The new methods are applied to common models of neuronal firing and to both simulated and experimental data

Application of the Convection–Dispersion Equation to Modelling Oral Drug Absorption

Models of systemic drug absorption after oral administration are frequently based on a direct or a delayed first-order rate process. In practice, the use of the first-order approach to predict drug concentrations in blood plasma frequently yields a considerable mismatch between predicted and measured concentration profiles. This is particularly true for the upswing of the plasma concentration after oral administration. The current investigation explores an alternative model to describe the absorption rate based on the convection–dispersion equation describing the transport of chemicals through the GI tract. This equation is governed by two parameters, transport velocity and dispersion coefficient. One solution of this equation for a specific set of initial and boundary conditions was used to model absorption of paracetamol in a 22-year-old man after oral administration. The GI-tract passage rate in this subject was influenced by co-administration of drugs that stimulate or delay gastric emptying. The transport-limited absorption function is more accurate in describing the plasma concentration versus time curve after oral administration than the first-order model. Additionally, it provides a mechanistic explanation for the observed curve through the differences in GI-tract passage rate

Residual plaque burden in patients with acute coronary syndromes after successful percutaneous coronary intervention

Objectives: The aim of this study was to characterize and evaluate the clinical impact of untreated atherosclerotic disease after percutaneous coronary intervention (PCI) in patients with acute coronary syndromes (ACS). Background: Residual atherosclerotic disease after successful PCI may predispose future major adverse cardiovascular events (MACE). Compared with intravascular ultrasound (IVUS), angiography underestimates the presence and severity of coronary artery disease. Methods: Following successful PCI of all clinically significant lesions in 697 patients with ACS, 3-vessel grayscale and radiofrequency IVUS was performed. Lesions were prospectively characterized, and patients were followed for a median of 3.4 years. A total of 3,229 untreated lesions (4.89 ± 1.98 lesions/patient) were identified by IVUS, with mean plaque burden (PB) of 49.6 ± 4.2%. Results: By angiography these nonculprit lesions were mild, with mean diameter stenosis of 38.9 ± 15.3%. At least 1 lesion with a PB <70% (PB70 lesion) was found in 220 (33%) patients. By multivariable analysis, a history of prior PCI and angiographic 3-vessel disease were independent predictors of PB70 lesions. Patients with PB70 lesions had greater total percent plaque volume, normalized PB, fibroatheromas, thin-cap fibroatheromas, and normalized volumes of necrotic core and dense calcium. Patients with PB70 lesions had greater 3-year rates of MACE due to untreated nonculprit lesions (20.8% vs. 7.7%, p < 0.0001). Among imaged nonculprit lesions, the proportion of PB70 lesions causing MACE was significantly greater than non-PB70 lesions (8.7% vs. 1.0%, p < 0.0001). Conclusions: After successful PCI of all angiographically significant lesions, overall untreated atherosclerotic burden remains high, and PB70 lesions are frequently present in the proximal and mid-coronary tree. Patients with PB70 lesions have greater atherosclerosis throughout the coronary tree, have more thin-cap fibroatheromas, and are at increased risk for future cardiovascular events. (PROSPECT: An Imaging Study in Patients With Unstable Atherosclerotic Lesions; NCT00180466