73 research outputs found
The influence of learner-generated domain representations on learning combinatorics and probability theory.
The aim of the current study was to examine the effects of providing support in the form of tools for constructing representations, and in particular the differential effects of the representational format of these tools (conceptual, arithmetical, or textual) in terms of perceived affordances and learning outcomes. The domain involved was combinatorics and probability theory. A between-subjects pre-test–post-test design was applied with secondary education students randomly distributed over four conditions. Participants completed the same tasks in a simulation-based learning environment. Participants in three experimental conditions were provided with a representational tool that could be used to construct a domain representation. The experimental manipulation concerned the format of the tool (conceptual, arithmetical, or textual). Participants in a control condition did not have access to a representational tool. Data from 127 students were analyzed. It was found that the construction of a domain representation significantly improved learning outcomes. The format in which students constructed a representation did not directly affect learning outcomes or the quality of the created domain representations. The arithmetical format, however, was the least stimulating for students to engage in externalizing their knowledge
The effects of representational format on learning combinatorics from an interactive computer simulation
The current study investigated the effects of different external representational formats on learning combinatorics and probability theory in an inquiry based learning environment. Five conditions were compared in a pre-test post-test design: three conditions each using a single external representational format (Diagram, Arithmetic, or Text), and two conditions using multiple representations (Text + Arithmetic or Diagram + Arithmetic). The major finding of the study is that a format that combines text and arithmetics was most beneficial for learning, in particular with regard to procedural knowledge, that is the ability to execute action sequences to solve problems. Diagrams were found to negatively affect learning and to increase cognitive load. Combining diagrams with arithmetical representations reduced cognitive load, but did not improve learning outcomes
Carbohydrate Status of Tulip Bulbs during Cold-Induced Flower Stalk Elongation and Flowering
Sub-tissue localization of phytochemicals in Cinnamomum camphora (L.) J. Presl. growing in Northern Italy
In the present paper, we focused our attention on Cinnamomum camphora (L.) J. Presl. (Lauraceae), studied at three levels: (i) micromorphological, with the analysis of the secretory structures and a novel in-depth histochemical characterization of the secreted compounds; (ii) phytochemical, with the characterization of the essential oils from young stems, fruits, and leaves, subjected to different conservation procedures (fresh, dried, stored at −20 °C, stored at −80 °C) and collected in two different years; (iii) bioactive, consisting of a study of the potential antibacterial activity of the essential oils. The micromorphological investigation proved the presence of secretory cells characterized by a multi-layered wall in the young stems and leaves. They resulted in two different types: mucilage cells producing muco-polysaccharides and oil cells with an exclusive terpene production. The phytochemical investigations showed a predominance of monoterpenes over sesquiterpene derivatives; among them, the main components retrieved in all samples were 1,8-cineole followed by α-terpineol and sabinene. Conservation procedures seem to only influence the amounts of specific components, i.e., 1,8-cineole and α-terpineol, while analyses on each plant part revealed the presence of some peculiar secondary constituents for each of them. Finally, the evaluation of the antibacterial activity of the essential oil showed a promising activity against various microorganisms, as Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa. In conclusion, we combined a micromorphological and phytochemical approach of the study on different plant parts of C. camphora, linking the occurrence of secretory cells to the production of essential oils. We compared, for the first time, the composition of essential oils derived from different plant matrices conserved with different procedures, allowing us to highlight a relation between the conservation technique and the main components of the profiles. Moreover, the preliminary antibacterial studies evidenced the potential activity of the essential oils against various microorganisms potentially dangerous for plants and humans
Adherence to Statin Therapy and Attainment of LDL Cholesterol Targets in an Outpatient Population of Type 2 Diabetes Patients:Analysis in the DIAbetes and LifEstyle Cohort Twente (DIALECT)
Objective: To assess adherence to statin therapy and its association with sociodemographic data, medical characteristics, LDLc levels, and LDLc target attainment in real-world T2D patients treated in secondary care.Research Design and Methods: Cross-sectional analyses were performed on baseline data of 393 patients in the DIAbetes and LifEstyle Cohort Twente (DIALECT). The medication possession ratio (MPR), calculated with pharmacy dispensing data, was used to determine adherence to statins for an intended period of 24 months. Statins were included in the analyses if they were used for at least six consecutive months with at least three dispenses. Adherence was defined as an MPR >= 80%. Associations with adherence were assessed using descriptive statistics and binary logistic regression.Results: Overall, 80% of the patients had a statin prescription and of those, 89% were adherent. The proportion of patients who reached LDLc targets o
PISA. The effect of paracetamol (acetaminophen) and ibuprofen on body temperature in acute stroke: Protocol for a phase II double-blind randomised placebo-controlled trial [ISRCTN98608690]
BACKGROUND: During the first days after stroke, one to two fifths of the patients develop fever or subfebrile temperatures. Body temperature is a strong prognostic factor after stroke. Pharmacological reduction of temperature in patients with acute ischaemic stroke may improve their functional outcome. Previously, we studied the effect of high dose (6 g daily) and low dose (3 g daily) paracetamol (acetaminophen) in a randomised placebo-controlled trial of 75 patients with acute ischemic stroke. In the high-dose paracetamol group, mean body temperature at 12 and 24 hours after start of treatment was 0.4°C lower than in the placebo group. The effect of ibuprofen, another potent antipyretic drug, on body-core temperature in normothermic patients has not been studied. AIM: The aim of the present trial is to study the effects of high-dose paracetamol and ibuprofen on body temperature in patients with acute ischaemic stroke, and to study the safety of these treatments. DESIGN: Seventy-five (3 × 25) patients with acute ischaemic stroke confined to the anterior circulation will be randomised to treatment with either: 400 mg ibuprofen, 1000 mg acetaminophen, or with placebo 6 times daily during 5 days. Body-temperatures will be measured with a rectal electronic thermometer at the start of treatment and after 24 hours. An infrared tympanic thermometer will be used to monitor body temperature at 2-hour intervals during the first 24 hours and at 12-hour intervals thereafter. The primary outcome measure will be rectal temperature at 24 hours after the start of treatment. The study results will be analysed on an intent-to-treat basis, but an on-treatment analysis will also be performed. No formal interim analysis will be carried out
Comparing the effects of representational tools in collaborative and individual inquiry learning
The effects of representational format on learning combinatorics from an interactive computer simulation
Onderzoekend leren met computersimulaties versus directe instructie binnen ROC Techniekonderwijs: Effecten op leerresultaten
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