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One important impact of invasive species may be to modify the behaviour of native taxa. For example, the invasion of highly toxic cane toads ( Bufo marinus) kills many anurophagous native predators, but other predators learn to recognize and avoid the toxic invader. We exposed native fish (northern trout gudgeons, Mogurnda mogurnda) and Dahl's aquatic frogs ( Litoria dahlii) to cane toad tadpoles, then monitored the predator's responses during subsequent trials. Both the frogs and fish initially attacked toad tadpoles, but rapidly learned not to do so. Fish and adult frogs retained their aversion for at least a week, whereas recently metamorphosed frogs did not. Clearly, the spread of cane toads through tropical Australia can modify feeding responses of native aquatic predators. For predators capable of rapid avoidance learning, the primary impact of cane toads may be on foraging behaviour rather than mortality. [ABSTRACT FROM AUTHOR]

Learning to avoid toxic prey items may aid native predators to survive the invasion of highly toxic species, such as cane toads Bufo marinus in tropical Australia. If the predators' initial aversion is generalized, native prey that resemble the toxic invader may receive a benefit through accidental mimicry. What ecological factors influence the acquisition of learned avoidance (and hence, the impact of invasion on both predators and native prey)? We conducted laboratory experiments to evaluate how the relative abundance of toad tadpoles compared to palatable native tadpoles ( Litoria caerulea and L. rubella) affected the ability of native aquatic predators to discriminate between these two prey types. Both fish (northern trout gudgeon, Mogurnda mogurnda) and frogs (Dahl's aquatic frog, Litoria dahlii) learned to discriminate between toads and frogs within an eight-day period. Higher abundance of toad tadpoles relative to frog tadpoles enhanced rates of predator learning, and thus reduced predation on toads and increased predation on native tadpoles. In the field, spatial and temporal variation in the relative abundance of cane toads compared to native frogs may influence the rates at which these novel toxic items are deleted from predator diets, and the duration of predator protection afforded to natives that resemble the invader. [ABSTRACT FROM AUTHOR]

This study investigated the effect of two instructional strategies, segmented and holistic, on the progression over time of learners' mental models toward that of an expert with the moderator of cognitive flexibility. Sixty-four juniors and seniors in a college metabolism course were randomly assigned to one of the two strategies for instruction on the electron transport chain. The data were analyzed with a repeated measures general linear model. Mental models progressed significantly for both strategies ( p < .001), and a significant interaction was found between cognitive flexibility and instructional strategy on mental model progression ( p = .02). The segmented strategy was superior for learners with higher cognitive flexibility but inferior to the holistic strategy for lower cognitive flexibility learners. Results have important implications for differentiating instruction on the basis of learner characteristics. [ABSTRACT FROM AUTHOR]

In a diagnostic problem solving operation of a computer-simulated chemical plant, chemical engineering students were randomly assigned to two groups: one studying product-oriented worked examples, the other practicing conventional problem solving. Effects of these instructional strategies on the progression of learners’ mental models were examined by comparing representations of their mental models with those of experts at three segments of the instruction. Progression of mental models for the worked example group was significantly greater than those using the problem-solving strategy. However, this progression did not manifest itself in learners’ troubleshooting performance measured by number of correct diagnosis and first time correct diagnosis. The implications of these results for designing instruction tailored to learners’ domain knowledge are discussed. [ABSTRACT FROM AUTHOR]

This study presents an application of a measure of learner involvement developed by Paas, Tuovinen, van Merrienboer, and Darabi (2005). These authors combined learners' performance scores with their perceived mental effort invested in instruction and used it to assess learner involvement in instructional conditions. The present study examines the differentiating attributes of the Paas et al. learner involvement measure by using data collected in an experiment that investigated the effectiveness of three computer-based instructional strategies: (a) conventional problem solving, (b) product-oriented worked examples, and (c) process-oriented worked examples. As hypothesized, learners using worked example strategies showed higher involvement scores than those in conventional problem solving. However, no differences in learner involvement were found between the two worked-example strategies. The implications of these findings for designing instructional strategies and suggestions for further research are discussed. [ABSTRACT FROM AUTHOR]

Backgroud: Short bowel syndrome (SBS) can lead to intestinal failure and require total or supplemental parenteral nutrition (TPN or PN, respectively). Glucagon-like peptide 2 (GLP-2) is a nutrient-dependent, proglucagon-derived gut hormone that stimulates intestinal adaptation. Objective: Our objective was to determine whether supplemental enteral nutrients (SEN) modulate the intestinotrophic response to a low dose of GLP-2 coinfused with PN in a rat model of SBS (60% jejunoileal resection plus cecectomy). Design: Rats were randomly assigned to 8 treatments by using a 2 × 2 × 2 factorial design and maintained with either TPN or PN for 7 d. The 3 main treatment effects were the following: transection or resection (TPN alone), ± SEN (days 4-6), and ± GLP-2 (100 μg . kg body wt-1 · d-1). Results: The treatments induced differential growth of duodenal and jejunal mucosa. Significant differences in villus height, crypt depth, dry mass, and concentrations of protein and DNA were observed between the treatments and TPN alone (SEN: 15-59% increase; GLP-2: 14-84% increase; and SEN + GLP-2: 63-160% increase). Plasma concentrations of bioactive GLP-2 were significantly greater with GLP-2 infusion (TPN alone: 25 ± 9 pmol/L; SEN: 29 ± 10 pmol/L; GLP-2: 59 ± 31 pmol/L; SEN + GLP-2: 246 ± 40 pmol/L) and correlated with mucosal growth. Jejunal sucrase activity (in U/cm) was significantly greater with SEN than without SEN. SEN + GLP-2 induced dramatic mucosal growth and greater plasma concentration of GLP-2 (SEN × GLP-2 interaction, P < 0.0001). Resection significantly increased expression of pro-glucagon mRNA in colon. Conclusions: Combination treatment with SEN and GLP-2 induced a synergistic response resulting in greater mucosal cellularity and digestive capacity in parenterally fed rats with SBS. This shows that SEN improve the intestinotrophic response to exogenous GLP-2, possibly by stimulating enterocyte proliferation and differentiation. [ABSTRACT FROM AUTHOR]

Mental models provide a powerful mechanism for storing knowledge in the human mind. Because of the ways these structures can influence human behavior, they have significant impact on virtually all forms of human activity. This is particularly so in the areas of instruction, learning, and expert performance. Because of the important role mental models play in these areas, this paper investigates their significance in learning a complex cognitive task in the context of troubleshooting and maintaining a complex simulated system. The focus of this investigation is on the learning-dependent progression of mental models as learners master the performance of a complex task. Accordingly, the learners' mental models were assessed at different points of accomplishing a complex troubleshooting skill within the realm of a simulation program. 26 engineering and chemical engineering students were recruited from engineering classes at Florida State University (14 male and 12 female). These subjects were randomly assigned to two experimental treatments (timed and self-paced). The measures of mental model progression during the second and third phase of the treatment showed that the subjects were faced with an uncertain situation which fragmented their understanding of the task. In terms of the development and progression of mental model, students ended up with the same mental model as their first one prior to receiving the treatment. The results are discussed with regard to mental model theory and instructional implications. [ABSTRACT FROM AUTHOR]

The articles published in four prominent distance education journals between 1997 and 2002 were categorized and the references cited were tallied. The study provides an opportunity to examine research topics, methods, and citation trends. The results can be used to review current research trends and to explore potential research directions. [ABSTRACT FROM PUBLISHER]

Total parenteral nutrition (TPN) induces dramatic mucosal hypoplasia in rat small intestine that is attenuated by insulin-like growth factor-I (IGF-l). Our aim was to determine the extent of TPN-induced intestinal atrophy and its response to infusion of IGF-l in mice. Mate C57BL/6 mice (18-22 g) were maintained with TPN, TPN plus co-infusion of recombinant human IGF-l [2.5 mg/(kg · d)] or oral feeding for 5 d. Body weights did not differ among the groups although serum IGF-l was increased by 78% with IGF-l infusion. IGF-l prevented the significant 25% reduction in mass of the intact small intestine due to TPN compared with oral feeding. Greater TPN-induced atrophy was noted in duodenum and jejunum than ileum. Jejunal atrophy induced by TPN reflected significant decreases in muscularis mass and concentrations of protein and DNA; mucosal cellularity was not altered by TPN. TPN induced a significant decrease in jejunal muscularis width that was reversed by IGF-l with no differences in mucosal villus height and crypt depth. Local expression of IGF-l binding protein (IGFBP)-5 positively modulates the intestinotrophic effects of IGF-l. Jejunal atrophy due to TPN and growth due to IGF-l were directly associated with expression of IGFBP-5 mRNA. TPN decreased IGFBP-5 mRNA by 60% and IGF-l increased IGFBP-5 mRNA by 200% with no change in IGF-l mRNA compared with oral feeding. In summary, TPN induces significant 25% atrophy of the mouse small intestine that is attenuated by IGF-l in association with increased expression of IGFBP-5. Compared with rats, TPN-induced atrophy is less severe and occurs primarily in the jejunal muscularis layer in mice. [ABSTRACT FROM AUTHOR]

The purpose of this article is to provide five empiric ally- derived guidelines for knowledge map construction tools that facilitate problem solving. First, the combinational rep resen- union principle proposes that conceptual and corresponding procedural knowledge should be represented together (rather than separately) within the knowledge map. Second, the con- textual enhancement principle proposes that the learner should provide information regarding the context of the problem within the knowledge map. Third, the spatial flexibility principle proposes that the space where learners represent concepts should be flexible and not artificially constrained. Fourth, the property association principle proposes that the magnitude of association between the concept and associated processes should be classified by the learner within the knowledge map. Fifth, the multiple representation principle proposes that the knowledge map construction tool should have the capacity to represent concepts through multiple modalities. The article presents a prototype of a new knowledge map construction tool that incorporates each of these principles. [ABSTRACT FROM AUTHOR]

The articles published in four prominent distance education journals between 1997 and 2002 were categorized and the references cited were tallied. The study provides an opportunity to examine research topics, methods, and citation trends. The results can be used to review current research trends and to explore potential research directions. [ABSTRACT FROM AUTHOR]

Compares the efficiency of an instructional condition for three groups of students differentiated by their use of an electronic performance support system (EPSS) to conduct a performance analysis project. Indication that the instruction was most efficient for those learners who showed greater competency in using the EPSS; Implications for using the technique as a means of formative evaluation of a course.

Identifying the causal gene(s) that connects genetic variation to a phenotype is a challenging problem in genome-wide association studies (GWASs). Here, we develop a systematic approach that integrates mouse liver co-expression networks with human lipid GWAS data to identify regulators of cholesterol and lipid metabolism. Through our approach, we identified 48 genes showing replication in mice and associated with plasma lipid traits in humans and six genes on the X chromosome. Among these 54 genes, 25 have no previously identified role in lipid metabolism. Based on functional studies and integration with additional human lipid GWAS datasets, we pinpoint Sestrin1 as a causal gene associated with plasma cholesterol levels in humans. Our validation studies demonstrate that Sestrin1 influences plasma cholesterol in multiple mouse models and regulates cholesterol biosynthesis. Our results highlight the power of combining mouse and human datasets for prioritization of human lipid GWAS loci and discovery of lipid genes. • Systematic method to combine mouse liver network and human lipid GWAS for discovery • Identification of a conserved liver cholesterol module across mouse populations • Prioritization of genes replicated in mouse and associated with human lipid traits • Validation of Sestrin1 as a gene that regulates cholesterol biosynthesis Here, Li et al. develop a systematic approach that integrates mouse liver co-expression networks together with human lipid GWAS datasets to identify lipid metabolism genes. Using this approach, they pinpoint Sestrin1 as a gene associated with cholesterol levels in humans and demonstrate that Sestrin1 protein can regulate cholesterol biosynthesis. [ABSTRACT FROM AUTHOR]

Intracranial pressure (ICP) data from traumatic brain injury (TBI) patients in the intensive care unit (ICU) cannot be interpreted appropriately without accounting for the effect of administered therapy intensity level (TIL) on ICP. A 15-point scale was originally proposed in 1987 to quantify the hourly intensity of ICP-targeted treatment. This scale was subsequently modified—through expert consensus—during the development of TBI Common Data Elements to address statistical limitations and improve usability. The latest 38-point scale (hereafter referred to as TIL) permits integrated scoring for a 24-h period and has a five-category, condensed version (TIL(Basic)) based on qualitative assessment. Here, we perform a total- and component-score analysis of TIL and TIL(Basic) to: 1) validate the scales across the wide variation in contemporary ICP management; 2) compare their performance against that of predecessors; and 3) derive guidelines for proper scale use. From the observational Collaborative European NeuroTrauma Effectiveness Research in TBI (CENTER-TBI) study, we extract clinical data from a prospective cohort of ICP-monitored TBI patients (n = 873) from 52 ICUs across 19 countries. We calculate daily TIL and TIL(Basic) scores (TIL24 and TIL(Basic)24, respectively) from each patient's first week of ICU stay. We also calculate summary TIL and TIL(Basic) scores by taking the first-week maximum (TILmax and TIL(Basic)max) and first-week median (TILmedian and TIL(Basic)median) of TIL24 and TIL(Basic)24 scores for each patient. We find that, across all measures of construct and criterion validity, the latest TIL scale performs significantly greater than or similarly to all alternative scales (including TIL(Basic)) and integrates the widest range of modern ICP treatments. TILmedian outperforms both TILmax and summarized ICP values in detecting refractory intracranial hypertension (RICH) during ICU stay. The RICH detection thresholds which maximize the sum of sensitivity and specificity are TILmedian ≥ 7.5 and TILmax ≥ 14. The TIL24 threshold which maximizes the sum of sensitivity and specificity in the detection of surgical ICP control is TIL24 ≥ 9. The median scores of each TIL component therapy over increasing TIL24 reflect a credible staircase approach to treatment intensity escalation, from head positioning to surgical ICP control, as well as considerable variability in the use of cerebrospinal fluid drainage and decompressive craniectomy. Since TIL(Basic)max suffers from a strong statistical ceiling effect and only covers 17% (95% confidence interval [CI]: 16–18%) of the information in TILmax, TIL(Basic) should not be used instead of TIL for rating maximum treatment intensity. TIL(Basic)24 and TIL(Basic)median can be suitable replacements for TIL24 and TILmedian, respectively (with up to 33% [95% CI: 31–35%] information coverage) when full TIL assessment is infeasible. Accordingly, we derive numerical ranges for categorising TIL24 scores into TIL(Basic)24 scores. In conclusion, our results validate TIL across a spectrum of ICP management and monitoring approaches. TIL is a more sensitive surrogate for pathophysiology than ICP and thus can be considered an intermediate outcome after TBI. [ABSTRACT FROM AUTHOR]

Intracranial pressure is routinely monitored in most intensive care units caring for patients with severe neurological insults and, together with continuous arterial blood pressure measurement, allows for monitoring of cerebral perfusion pressure (CPP). CPP is the driving pressure of blood flow to the brain and is used to guide therapy. However, there is considerable inconsistency in the literature regarding how CPP is technically measured and, more specifically, the appropriate placement of the arterial pressure transducer. Depending on patient positioning and where the arterial pressure transducer is placed, the mean arterial pressure used for CPP calculation can vary widely by up to 15 mm Hg, which is greater than the acceptable variation in target ranges used clinically. Physiologically, the arterial pressure transducer should be placed at the level of the foramen of Monro for CPP measurement, but it is commonly set at the level of the right atrium for systematic measurement. Mean arterial pressure measurement at the level of the right atrium can lead to overestimation and potentially critically low actual CPP levels when the head is elevated, and measurement at the level of the foramen of Monro will underestimate systemic pressures, increasing the risk of excessive and unnecessary use of vasopressors and fluid. At the Karolinska University Hospital neurointensive care unit, we have used a split dual-transducer system, measuring arterial pressure both at the level of the foramen of Monro and at the level of the right atrium from a single arterial source. In doing so, we work with constants and can monitor and target optimum arterial pressures to better secure perfusion to all organs, with potentially less risk of cerebral ischemia or overuse of vasopressors and fluids, which may affect outcome. [ABSTRACT FROM AUTHOR]

Contusion expansion (CE) is a potentially treatable outcome predictor in traumatic brain injury (TBI), and a suitable end-point for hemostatic therapy trials. However, there is no consensus on the definition of clinically relevant CE, both in terms of measurement criteria (absolute vs. relative volume increase) and cutoff values. In light of this, the aim of this study was to assess the predictive abilities of different CE definitions on outcome. We performed a multi-center observational cohort study of adults with moderate-to-severe TBI treated in an intensive care unit. The exposure of interest was CE, defined as the absolute and relative volume change between the first and second computed tomography scan. The primary outcome was the Glasgow Outcome Scale (GOS) at 6–12 months post-injury, dichotomized into unfavorable (GOS ≤3) or favorable (GOS ≥4). The secondary outcome was all-cause mortality. In total, 798 patients were included, with a median duration of 7.0 h between the first and second CT scan. The median absolute and relative CE was 1.5 mL (interquartile range [IQR] 0.1–8.3 mL) and 100% (IQR 10–530%), respectively. Both CE forms were independently associated with unfavorable GOS. Absolute CE outperformed relative CE in predicting both unfavorable GOS (area under the curve [AUC]: 0.65 vs. 0.60, p = 0.002) and all-cause mortality (AUC: 0.66 vs. 0.60, p = 0.003). For dichotomized CE, absolute cutoffs of 1–10 mL yielded the best results. We conclude that absolute CE demonstrates stronger outcome correlation than relative CE. In studies focusing on lesion progression in TBI, it may be advantageous to use absolute CE as the primary outcome metric. For dichotomized outcomes, cutoffs between 1 and 10 mL are suggested, depending on the desired sensitivity-specificity balance. [ABSTRACT FROM AUTHOR]

Background: The prognosis of penetrating traumatic brain injury (pTBI) is poor yet highly variable. Current computerized tomography (CT) severity scores are commonly not used for pTBI prognostication but may provide important clinical information in these cohorts. Methods: All consecutive pTBI patients from two large neurotrauma databases (Helsinki 1999–2015, Stockholm 2005–2014) were included. Outcome measures were 6-month mortality and unfavorable outcome (Glasgow Outcome Scale 1–3). Admission head CT scans were assessed according to the following: Marshall CT classification, Rotterdam CT score, Stockholm CT score, and Helsinki CT score. The discrimination (area under the receiver operating curve, AUC) and explanatory variance (pseudo-R2) of the CT scores were assessed individually and in addition to a base model including age, motor response, and pupil responsiveness. Results: Altogether, 75 patients were included. Overall 6-month mortality and unfavorable outcome were 45% and 61% for all patients, and 31% and 51% for actively treated patients. The CT scores' AUCs and pseudo-R2s varied between 0.77–0.90 and 0.35–0.60 for mortality prediction and between 0.85–0.89 and 0.50–0.57 for unfavorable outcome prediction. The base model showed excellent performance for mortality (AUC 0.94, pseudo-R2 0.71) and unfavorable outcome (AUC 0.89, pseudo-R2 0.53) prediction. None of the CT scores increased the base model's AUC (p > 0.05) yet increased its pseudo-R2 (0.09–0.15) for unfavorable outcome prediction. Conclusion: Existing head CT scores demonstrate good-to-excellent performance in 6-month outcome prediction in pTBI patients. However, they do not add independent information to known outcome predictors, indicating that a unique score capturing the intracranial severity in pTBI may be warranted. [ABSTRACT FROM AUTHOR]

Patients with traumatic brain injury are a heterogeneous population, and the most severely injured individuals are often treated in an intensive care unit (ICU). The primary injury at impact, and the harmful secondary events that can occur during the first week of the ICU stay, will affect outcome in this vulnerable group of patients. We aimed to identify clinical variables that might distinguish disease trajectories among patients with traumatic brain injury admitted to the ICU. We used data from the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) prospective observational cohort study. We included patients aged 18 years or older with traumatic brain injury who were admitted to the ICU at one of the 65 CENTER-TBI participating centres, which range from large academic hospitals to small rural hospitals. For every patient, we obtained pre-injury data and injury features, clinical characteristics on admission, demographics, physiological parameters, laboratory features, brain biomarkers (ubiquitin carboxy-terminal hydrolase L1 [UCH-L1], S100 calcium-binding protein B [S100B], tau, neurofilament light [NFL], glial fibrillary acidic protein [GFAP], and neuron-specific enolase [NSE]), and information about intracranial pressure lowering treatments during the first 7 days of ICU stay. To identify clinical variables that might distinguish disease trajectories, we applied a novel clustering method to these data, which was based on a mixture of probabilistic graph models with a Markov chain extension. The relation of clusters to the extended Glasgow Outcome Scale (GOS-E) was investigated. Between Dec 19, 2014, and Dec 17, 2017, 4509 patients with traumatic brain injury were recruited into the CENTER-TBI core dataset, of whom 1728 were eligible for this analysis. Glucose variation (defined as the difference between daily maximum and minimum glucose concentrations) and brain biomarkers (S100B, NSE, NFL, tau, UCH-L1, and GFAP) were consistently found to be the main clinical descriptors of disease trajectories (ie, the leading variables contributing to the distinguishing clusters) in patients with traumatic brain injury in the ICU. The disease trajectory cluster to which a patient was assigned in a model was analysed as a predictor together with variables from the IMPACT model, and prediction of both mortality and unfavourable outcome (dichotomised GOS-E ≤4) was improved. First-day ICU admission data are not the only clinical descriptors of disease trajectories in patients with traumatic brain injury. By analysing temporal variables in our study, variation of glucose was identified as the most important clinical descriptor that might distinguish disease trajectories in the ICU, which should direct further research. Biomarkers of brain injury (S100B, NSE, NFL, tau, UCH-L1, and GFAP) were also top clinical descriptors over time, suggesting they might be important in future clinical practice. European Union 7th Framework program, Hannelore Kohl Stiftung, OneMind, Integra LifeSciences Corporation, and NeuroTrauma Sciences. [ABSTRACT FROM AUTHOR]