Understanding the “Pathway” Towards a Searcher’s Learning Objective

Search systems are often used to support learning-oriented goals. This trend has given rise to the “search-as-learning” movement, which proposes that search systems should be designed to support learning. To this end, an important research question is: How does a searcher’s type of learning objective (LO) influence their trajectory (or pathway ) toward that objective? We report on a lab study (N = 36) in which participants gathered information to meet a specific type of LO. To characterize LOs and pathways , we leveraged Anderson and Krathwohl’s (A&K’s) taxonomy [ 3 ]. A&K’s taxonomy situates LOs at the intersection of two orthogonal dimensions: (1) cognitive process (CP) (remember, understand, apply, analyze, evaluate, and create) and (2) knowledge type (factual, conceptual, procedural, and metacognitive knowledge). Participants completed learning-oriented search tasks that varied along three CPs (apply, evaluate, and create) and three knowledge types (factual, conceptual, and procedural knowledge). A pathway is defined as a sequence of learning instances (e.g., subgoals) that were also each classified into cells from A&K’s taxonomy. Our study used a think-aloud protocol, and pathways were generated through a qualitative analysis of participants’ think-aloud comments and recorded screen activities. We investigate three research questions. First, in RQ1, we study the impact of the LO on pathway characteristics (e.g., pathway length). Second, in RQ2, we study the impact of the LO on the types of A&K cells traversed along the pathway. Third, in RQ3, we study common and uncommon transitions between A&K cells along pathways conditioned on the knowledge type of the objective. We discuss implications of our results for designing search systems to support learning.

Evaluation of Probiotic and Antimicrobial Potential of Canine Derived–Lactobacilli

Antibiotics are commonly used to treat infectious diseases. However, massive and inappropriate antibiotics usage cause many problems including the emergence and spread of antibiotic-resistant bacteria. To avoid this issue, in modern countries the interest of using probiotics in feed supplementation to promote health and prevent or treat intestinal infectious diseases in companion animals like dogs has been increasing. We evaluate the probiotic potential of Lactobacilli isolated from healthy dogs faeces. The isolated Lactobacilli were first confirmed by 16SrRNA sequencing, then in vitro tests were conducted to assess survival potential of Lactobacilli under simulated gastrointestinal conditions and adhesion ability to gut epithelia, effects on epithelial barrier function, anti-inflammatory activities, effects on defensin peptides (beta-defensin 3) and inhibitory effects on common pathogens. Lactobacilli showed considerable potential to survive in simulated gastrointestinal environmental conditions, low pH, high bile salt concentrations along with good adhesion properties with MODE-K cells. Pathogenic bacterial growth and their adhesion to MODE-K cells was significantly inhibited by Lactobacilli. Real-time PCR analyses further demonstrated that L. acidophilus strain AR1 and AR3 inhibit Salmonella-induced proinflammatory cytokines (IL-6, IL-8, 1ꞵ) production and reinforce expression of tight junction protein (occludin). None of the strain induce mRNA expression of beta-defensin 3 in MODE-K cells. Based on in vitro results the L. acidophilus strain AR1 has potential to be supplemented in canine feed. However, further in vivo studies investigating health-promoting effects are awaited.

P31: INTESTINAL GIP RELEASE MODIFICATIONS WOULD BE RELATED TO DUODENAL EXCLUSION: BARIATRIC SURGERY CONSEQUENCES

Introduction The surgical techniques employed in the treatment of obesity discovered consequences on the global enterohomonal equilibrium. Many hypotheses focused on these enterohormonal system to explain the improvement of Type 2 Diabetes mellitus; as many other functional improvements. GIP is a hormone released for the duodenal and jejunal K cells, which had been implied in the glucose homeostasis. Our purpose was studied the changes in K cells populations, that could be related to the GIP serum level. Method We employed 16 non obese euglycemic male Wistar rats, randomised in the surgical groups. These groups were the surgical techniques (Sleeve gastric –SG-, Roux en Y Gastric Bypass –RYGB- and massive intestinal resection –IR50-), and two controls (fasting and Sham). After three months, rats were sacrificed. The intestinal portions (duodenum, jejunum and ileum) were resected and processed for the immunocytochemical technique. Result analysis showed several aspects. We found a significant increase of GIP K-cells (number GIP+/mm2 intestinal portion) in the duodenum of RYGB and RI50 versus both control groups. Other data showed a significant decrease of GIP K-cells in SG jejunum versus both control groups. Ileum did not significances. Conclusion GIP hormone was related to the nutrient flow through the intestine. Our data showed that GIP expression was inverse to the exclusion to this flow, as in RYGB technique. The increase was severe in IR50 too, which the duodenum was not affected. This mechanism revealed a complex physiologic mechanism, probably established by the feed-back with other hormones, as PPY. Take-home message The metabolic consequences after bariatric surgeries are related in enterohormones changes. The GIP release cellularity suffer changes according to the flow of nutrients.

Individual and combined effects of GIP and xenin on differentiation, glucose uptake and lipolysis in 3T3-L1 adipocytes

The incretin hormone glucose-dependent insulinotropic polypeptide (GIP), released postprandially from K-cells, has established actions on adipocytes and lipid metabolism. In addition, xenin, a related peptide hormone also secreted from K-cells after a meal, has postulated effects on energy regulation and lipid turnover. The current study has probed direct individual and combined effects of GIP and xenin on adipocyte function in 3T3-L1 adipocytes, using enzyme-resistant peptide analogues, (d-Ala2)GIP and xenin-25-Gln, and knockdown (KD) of receptors for both peptides. (d-Ala2)GIP stimulated adipocyte differentiation and lipid accumulation in 3T3-L1 adipocytes over 96 h, with xenin-25-Gln evoking similar effects. Combined treatment significantly countered these individual adipogenic effects. Individual receptor KD impaired lipid accumulation and adipocyte differentiation, with combined receptor KD preventing differentiation. (d-Ala2)GIP and xenin-25-Gln increased glycerol release from 3T3-L1 adipocytes, but this lipolytic effect was significantly less apparent with combined treatment. Key adipogenic and lipolytic genes were upregulated by (d-Ala2)GIP or xenin-25-Gln, but not by dual peptide culture. Similarly, both (d-Ala2)GIP and xenin-25-Gln stimulated insulin-induced glucose uptake in 3T3-L1 adipocytes, but this effect was annulled by dual treatment. In conclusion, GIP and xenin possess direct, comparable, lipogenic and lipolytic actions in 3T3-L1 adipocytes. However, effects on lipid metabolism are significantly diminished by combined administration.

On the number of empty cells in the allocation scheme of indistinguishable particles

The allocation scheme of \(n\) indistinguishable particles into \(N\) different cells is studied. Let the random variable \(\mu_0(n,K,N)\) be the number of empty cells among the first \(K\) cells. Let \(p=\frac{n}{n+N}\). It is proved that \(\frac{\mu_0(n,K,N)-K(1-p)}{\sqrt{ K p(1-p)}}\) converges in distribution to the Gaussian distribution with expectation zero and variance one, when \(n,K, N\to\infty\) such that \(\frac{n}{N}\to\infty\) and \(\frac{n}{NK}\to 0\). If \(n,K, N\to\infty\) so that \(\frac{n}{N}\to\infty\) and \(\frac{NK}{n}\to \lambda\), where \(0<\lambda<\infty\), then \(\mu_0(n,K,N)\) converges in distribution to the Poisson distribution with parameter \(\lambda\). Two applications of the results are given to mathematical statistics. First, a method is offered to test the value of \(n\). Then, an analogue of the run-test is suggested with an application in signal processing.

Cytotoxic effects of manganese oxide nanoparticles in combination with microbial components on intestinal epithelial cells

Background: Manganese oxide has been shown to cause toxicity and is associated with occupational-related disease (e.g., welders). With the goal to improve several biomedical areas, manganese oxide nanoparticles (MnO NP) are being considered for use in drug delivery and magnetic resonance imaging (MRI) to obtain high resolution anatomical images of tumors and gastrointestinal (GI) inflammation. Regardless of whether it is intentional or unintentional ingestion, the GI tract has been shown to be the primary route of entry for metal nanoparticles including MnO NP. However, studies assessing toxicity of MnO NP for intestinal epithelial cells (IECs) are virtually nonexistent. Methods: Given the proximity to the GI lumen, assessing the effects of nanoparticles on IECs in the presence of bacterial components presents a more holistic model of exposure. Therefore, we examined the effects of MnO NP alone and MnO NP in combination with Escherichia coli LF82 bacterial lysate on selected functions of MODE-K cells, a murine intestinal epithelial cell line. Data were analyzed using one-way ANOVA. Differences with p < 0.05 were considered significant. Results: Results showed MnO NP plus E. coli LF82 lysate added to MODE-K cells severely inhibited monolayer scratch wound healing, enhanced the secretion of interleukin 6 (IL-6), and induced mitochondrial dysfunction. Conclusions: Overall, our findings show that toxicity of MnO NP deleteriously affected MODE-K cells and demonstrated the necessity to integrate other environmental factors, such as microbial components and/or inflammatory cytokines, into studies assessing effects of nanoparticles on mucosal epithelia.

Variation in the life history strategy underlies functional diversity of tumors

Classical r- vs. K-selection theory describes the trade-offs between high reproductive output and competitiveness and guides research in evolutionary ecology. While its impact has waned in the recent past, cancer evolution may rekindle it. Herein, we impose r- or K- selection on cancer cell lines to obtain strongly proliferative r cells and highly competitive K cells to test ideas on life-history strategy evolution. RNA-seq indicates that the trade-offs are associated with distinct expression of genes involved in the cell cycle, adhesion, apoptosis, and contact inhibition. Both empirical observations and simulations based on an ecological competition model show that the trade-off between cell proliferation and competitiveness can evolve adaptively. When the r and K cells are mixed, they exhibit strikingly different spatial and temporal distributions. Due to this niche separation, the fitness of the entire tumor increases. The contrasting selective pressure may operate in a realistic ecological setting of actual tumors.