370 research outputs found

    What Can Be Learned from Computer Modeling? Comparing Expository and Modeling Approaches to Teaching Dynamic Systems Behavior

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    Computer modeling has been widely promoted as a means to attain higher order learning outcomes. Substantiating these benefits, however, has been problematic due to a lack of proper assessment tools. In this study, we compared computer modeling with expository instruction, using a tailored assessment designed to reveal the benefits of either mode of instruction. The assessment addresses proficiency in declarative knowledge, application, construction, and evaluation. The subscales differentiate between simple and complex structure. The learning task concerns the dynamics of global warming. We found that, for complex tasks, the modeling group outperformed the expository group on declarative knowledge and on evaluating complex models and data. No differences were found with regard to the application of knowledge or the creation of models. These results confirmed that modeling and direct instruction lead to qualitatively different learning outcomes, and that these two modes of instruction cannot be compared on a single “effectiveness measure”

    Mechanismen en CAD/CAM systemen

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    Eczema phenotypes and risk of allergic and respiratory conditions in school age children

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    Background: Eczema phenotypes based on eczema onset and persistence might better identify groups prone to allergic and respiratory conditions than a binary definition of eczema. We examined the associations of childhood eczema phenotypes with allergic sensitization, allergy, asthma and lung function at school age. Methods: This study among 4277 children was embedded in a multi-ethnic population-based prospective cohort study. Five eczema phenotypes (never, early transient, mid-transient, late transient, persistent) based on parental-reported physician-diagnosed eczema from age 6 months until 10 years were identified. At age 10 years, allergic sensitization was measured by skin prick tests, physician-diagnosed allergy and asthma by parent-reported questionnaires, and lung function by spirometry. Adjusted linear, logistic and multinomial regression models were applied. Results: Compared with never eczema, all eczema phenotypes were associated with increased risks of asthma (odds ratios (OR) range (95% confidence interval): 2.68 (1.58, 4.57) to 11.53 (6.65, 20.01)), food and inhalant allergic sensitization (1.72 (1.25, 2.36) to 12.64 (7.20, 22.18)), and physician-diagnosed inhalant allergy (1.92 (1.34, 2.74) to 11.91 (7.52, 18.86)). Strongest effect estimates were observed of early and persistent eczema with the risk of physician-diagnosed food allergy (OR 6.95 (3.76, 12.84) and 35.05 (18.33, 70.00), respectively) and combined asthma and physician-diagnosed allergy (7.11 (4.33, 11.67) and 29.03 (15.27, 55.22), respectively). Eczema phenotypes were not associated with lung function measures. Conclusion: Eczema phenotypes were differentially associated with risks of respiratory and allergic conditions in school-aged children. Children with early transient and persistent eczema might benefit from more intense follow-up for early identification and treatment of asthma and allergies

    Serum antimĂŒllerian hormone levels best reflect the reproductive decline with age in normal women with proven fertility: A longitudinal study

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    Objective: The aim of this study was to assess which of the basal ovarian reserve markers provides the best reflection of the changes occurring in ovarian function over time (i.e., reproductive aging). Design: Prospective longitudinal study. Setting: Healthy volunteers in an academic research center. Patient(s): Eighty-one women with normal reproductive performance during the course of their lives were longitudinally assessed. In this select group of women, becoming chronologically older was considered as a proxy variable for becoming older from a reproductive point of view. Intervention(s): The women were assessed twice, with on average a 4-year interval (T 1 and T 2). The number of antral follicles on ultrasound (AFC) and blood levels of antimĂŒllerian hormone (AMH), FSH, inhibin B, and E 2 were assessed. Main Outcome Measure(s): Longitudinal changes of the markers mentioned and the consistency of these parameters over time. Result(s): The mean ages at T 1 and T 2 were 39.6 and 43.6 years, respectively. Although AFC was strongly associated with age in a cross-sectional fashion, it did not change over time. The AMH, FSH, and inhibin B levels showed a significant change over time, in contrast to E 2 levels. The AMH and AFC were highly correlated with age both at T 1 and T 2, whereas FSH and inhibin B predominantly changed in women more than 40 years of age. To assess the consistency of these parameters over time, we investigated whether a woman's individual level above or below the mean of her age group at T 1 remained above or below the mean of her age group at T 2. Serum AMH concentrations showed the best consistency, with AFC as second best. The FSH and inhibin B showed only modest consistency, whereas E 2 showed no consistency at all. Conclusion(s): These results indicate that serum AMH represents the best endocrine marker to assess the age-related decline of reproductive capacity

    Association between nasal and nasopharyngeal bacterial colonization in early life and eczema phenotypes

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    Background: An association has been reported between early life Staphylococcus aureus nasal carriage and higher risk of childhood eczema, but it is unclear whether this relationship is causal and associations with other bacterial species are unclear.Objective: To examine the associations of early life nasal and nasopharyngeal bacterial carriage with eczema phenotypes, and the direction of any associations identified.Methods: Among 996 subjects of a population-based prospective cohort study, nasal swabs for Staphylococcus aureus, and nasopharyngeal swabs for Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae were collected and cultured from age 6 weeks to 6 years. Never, early, mid-, late transient and persistent eczema phenotypes were identified from parental-reported physician-diagnosed eczema from age 6 months until 10 years. Multinomial regression models and cross-lagged models were applied.Results: Staphylococcus aureus nasal carriage at 6 months was associated with an increased risk of early transient and persistent eczema (OR (95% CI): 2.69 (1.34, 5.39) and 4.17 (1.12, 15.51)). The associations between Staphylococcus aureus nasal carriage and eczema were mostly cross-sectional, and not longitudinal. No associations of Staphylococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenza nasopharyngeal bacterial carriage with eczema and eczema phenotypes were observed (OR range (95% CI): 0.71 (0.35, 1.44) to 1.77 (0.84, 3.73)).Conclusions: Early life Staphylococcus aureus nasal carriage, but not Staphylococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenza nasopharyngeal carriage, was associated with early transient and persistent eczema. Staphylococcus aureus nasal carriage and eczema were mostly cross-sectionally associated, and not longitudinally, making a causal relationship in either direction unlikely.Public Health and primary carePrevention, Population and Disease management (PrePoD

    Maternal and neonatal 25-hydroxyvitamin D concentrations and school-age lung function, asthma and allergy. The Generation R Study

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    Background: Vitamin D deficiency in early life might affect the developing lung and immune system, and subsequently influence the risk of asthma and allergy in later life. Objective: We examined the associations of 25‐hydroxyvitamin D concentrations in mid‐gestation and at birth with lung function, asthma, inhalant allergic sensitization and inhalant allergy at school‐age. Methods: This study among 4951 children and their mothers was embedded in a population‐based prospective cohort in Rotterdam, the Netherlands. Maternal ve‐ nous blood samples in mid‐gestation and umbilical cord blood samples at birth were used to determine 25‐hydroxyvitamin D concentrations. At age 10 years, lung func‐ tion was measured by spirometry, current asthma and physician‐diagnosed inhalant allergy by questionnaire, and inhalant allergic sensitization by skin prick tests. We used multivariable regression models to examine associations. Results: Higher 25‐hydroxyvitamin D concentrations in mid‐gestation were associ‐ ated with a higher forced vital capacity (FVC), but a lower forced expiratory volume in 1 second/FVC (FEV1/FVC) and a lower forced expiratory flow after exhaling 75% of FVC (FEF75) (Z‐score differences [95% CI] 0.02 [0.00, 0.03], −0.02 [−0.03, −0.01] and −0.01 [‐0.03, −0.00], respectively, per 10 nmol/L 25‐hydroxyvitamin D), but not with asthma. Furthermore, higher 25‐hydroxyvitamin D concentrations in mid‐gesta‐ tion were associated with an increased risk of inhalant allergy (Odds Ratio [95% CI] 1.07 [1.02, 1.12]), but not with inhalant allergic sensitization. After additional adjust‐ ment for child's 25‐hydroxyvitamin D concentrations at the age of 6 years, only the associations of 25‐hydroxyvitamin D concentrations in mid‐gestation with FEV1

    Stereoscopic Analysis of the 19 May 2007 Erupting Filament

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    A filament eruption, accompanied by a B9.5 flare, coronal dimming and an EUV wave, was observed by the Solar TERrestrial Relations Observatory (STEREO) on 19 May 2007, beginning at about 13:00 UT. Here, we use observations from the SECCHI/EUVI telescopes and other solar observations to analyze the behavior and geometry of the filament before and during the eruption. At this time, STEREO A and B were separated by about 8.5 degrees, sufficient to determine the three-dimensional structure of the filament using stereoscopy. The filament could be followed in SECCHI/EUVI 304 A stereoscopic data from about 12 hours before to about 2 hours after the eruption, allowing us to determine the 3D trajectory of the erupting filament. From the 3D reconstructions of the filament and the chromospheric ribbons in the early stage of the eruption, simultaneous heating of both the rising filamentary material and the chromosphere directly below is observed, consistent with an eruption resulting from magnetic reconnection below the filament. Comparisons of the filament during eruption in 304 A and Halpha show that when it becomes emissive in He II, it tends to disappear in Halpha, indicating that the disappearance probably results from heating or motion, not loss, of filamentary material.Comment: Accepted for publication in Solar Physic
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