Search results for "Modeling"
showing 10 items of 4489 documents
Uncertainty quantification in simulations of epidemics using polynomial chaos.
2012
Mathematical models based on ordinary differential equations are a useful tool to study the processes involved in epidemiology. Many models consider that the parameters are deterministic variables. But in practice, the transmission parameters present large variability and it is not possible to determine them exactly, and it is necessary to introduce randomness. In this paper, we present an application of the polynomial chaos approach to epidemiological mathematical models based on ordinary differential equations with random coefficients. Taking into account the variability of the transmission parameters of the model, this approach allows us to obtain an auxiliary system of differential equa…
The mediating role of constructs representing reasoned-action and automatic processes on the past behavior-future behavior relationship.
2020
Abstract Objective Past behavior has been consistently shown to predict and explain future behavior. It has been proposed that past behavior effects reflect both reasoned action and automatic processes. The current study sought to explore the mediation of past behavior-future behavior relationship via constructs reflecting these processes across three populations and behaviors: binge drinking in university students, flossing in adults, and parental sun safety behavior of children 2 – 5 years of age. Furthermore, this study used a measure of past behavior that combined long-term, recent, and routine patterns of behavioral engagement. Method A prospective design with two waves of data collect…
Biochemical bone markers compared with bone density measurement by dual energy X-ray absorptiometry
1995
In contrast to medical imaging, the biochemical markers allow a more frequent determination and are not as invasive as histomorphometric methods. We investigated biochemical markers of type I collagen compared with bone density measurements in 85 females between 41 and 89 years of age (median: 57 years). The bone density measurements were performed by dual energy X-ray absorptiometry (DXA) on the lumbar spine (L1-4). The bone density measurements were stated as a percentage of the norm. All patients were divided into three groups: I =80%; II = 80-130%; III =120%. Based on this classification the median concentration of the I-carboxyterminal propeptide of type I collagen in serum (S-PICP) as…
Empirical examination of executive functioning, ADHD associated behaviors, and functional impairments in adults with persistent ADHD, remittent ADHD,…
2019
Abstract Background Previous studies suggest that childhood attention deficit hyperactivity disorder (ADHD) may continue in adulthood, producing adverse effects. Therefore, identifying factors that help to differentiate characteristics of ADHD persistence and remission has practical implications for evaluation and treatment. The first aim of this study was to analyze differences in executive functions (shift, working memory, inhibition, and plan/organize), symptoms associated with ADHD (inattention, hyperactivity, emotional lability, and self-concept), and functional impairments in adults with persistent ADHD (ADHD-P), with remittent ADHD (ADHD-R), and without ADHD (N-ADHD). The second aim …
Bone’s Structural Diversity in Adult Females Is Established before Puberty
2009
Bone must be rigid for leverage yet light for mobility. We studied how bone modeling and remodeling fashioned differences in bone size, shape, and mass during growth to achieve these properties in adulthood.We measured the structural features of a tibial cross-section using quantitative computed tomography and markers of remodeling in 258 10- to 13-yr-old girls during 2 yr and in 108 of their mothers.Tibia total cross-sectional area and mass correlated between daughters and their mothers (r = 0.34 and 0.44, respectively, both P0.01). The location of a daughter's tibial total cross-sectional area, medullar area, and bone mass in the lower, middle, or upper part of the sample distribution was…
Hypogonadism and Hormone Replacement Therapy on Bone Mass of Adult Women with Thalassemia Major
2002
We studied bone mass and metabolism in 30 adult women (age 28.5 +/- 1.3) with thalassemia major (TM) and evaluated whether prolonged hormone replacement therapy (HRT) was able to optimize bone accrual. TM patients had reduced bone mass, increased bone turnover and lower serum gonadotropin and estradiol levels compared with 10 normal women of similar age. A significant correlation was found between bone mass and sex hormone levels. Six TM patients with normal ovarian function had normal bone turnover markers and modestly low bone mass (lumbar spine -1.29 +/- 0.31; femoral neck -0.60+/-0.21; Z-score). The other 24 TM women were hypogonadic and had significantly lower bone mass for age (lumbar…
Clinical and radiographic performance of self‐locking conical connection implants in the posterior mandible: Five‐year results of a two‐centre prospe…
2021
Abstract Objective This prospective study aims to assess the 5‐year clinical performance of implants with internal conical connection and platform‐switched abutments in the posterior mandible. Material and Methods Healthy adults missing at least two teeth in the posterior mandible and with a natural tooth mesial to the implant site received two or three adjacent implants. After a transmucosal healing period single crown restorations were cemented on platform‐switched abutments. Changes in marginal bone levels were investigated in standardized periapical radiographs from surgery and loading (baseline) to 60‐months post‐loading. Results Twenty‐four patients received 52 implants. Bone remodell…
A Graph-Grammar Approach to Represent Causal, Temporal and Other Contexts in an Oncological Patient Record
1996
AbstractThe data of a patient undergoing complex diagnostic and therapeutic procedures do not only form a simple chronology of events, but are closely related in many ways. Such data contexts include causal or temporal relationships, they express inconsistencies and revision processes, or describe patient-specific heuristics. The knowledge of data contexts supports the retrospective understanding of the medical decision-making process and is a valuable base for further treatment. Conventional data models usually neglect the problem of context knowledge, or simply use free text which is not processed by the program. In connection with the development of the knowledge-based system THEMPO (The…
Gully erosion susceptibility assessment by means of GIS-based logistic regression: A case of Sicily (Italy)
2014
article i nfo Article history: This research aims at characterizing susceptibility conditions to gully erosion by means of GIS and multivariate statistical analysis. The study area is a 9.5 km 2 river catchment in central-northern Sicily, where agriculture ac- tivities are limited by intense erosion. By means of field surveys and interpretation of aerial images, we prepared a digitalmap of thespatial distribution of 260 gulliesinthestudy area.Inaddition,fromavailable thematicmaps, a 5 m cell size digital elevation model and field checks, we derived 27 environmental attributes that describe the variability of lithology, land use, topography and road position. These attributes were selected f…
Simulating the evolution of stakes on Réunion Island in a context of coastal risk
2017
This paper describes a model and a simulation tool which aim at help decision-makers and planners dealing with their processes for territorial prospective analysis. It is based on a practical study case, located on Réunion Island (France). This study has been carried out within the VULNERARE research program, granted by Foundation de France: one of VULNERARE aims is to estimate and assess Réunion's vulnerability in the next 30 years, in relation to coastal risk. This paper is specifically focussing on the dynamics and the future state of two important stakes: population and urban structures. Will urban development of littoral zones increase? How fast and which type of population will be exp…