Asymmetric Lineshapes of Efimov Resonances in Mass-Imbalanced Ultracold Gases

The resonant profile of the rate coefficient for three-body recombination into a shallow dimer is investigated for mass-imbalanced systems. In the low-energy limit, three atoms collide with zero-range interactions, in a regime where the scattering lengths of the heavy–heavy and the heavy–light subsystems are positive and negative, respectively. For this physical system, the adiabatic hyperspherical representation is combined with a fully semi-classical method and we show that the shallow dimer recombination spectra display an asymmetric lineshape that originates from the coexistence of Efimov resonances with Stückelberg interference minima. These asymmetric lineshapes are quantified utilizing the Fano profile formula. In particular, a closed-form expression is derived that describes the width of the corresponding Efimov resonances and the Fano lineshape asymmetry parameter q. The profile of Efimov resonances exhibits a q-reversal effect as the inter- and intra-species scattering lengths vary. In the case of a diverging asymmetry parameter, i.e., |q|→∞, we show that the Efimov resonances possess zero width and are fully decoupled from the three-body and atom–dimer continua, and the corresponding Efimov metastable states behave as bound levels.

When color coding backfires: A guidance reversal effect when learning with realistic visualizations

Digital learning increasingly makes use of realistic visualizations, although realism can be demanding for learners. Color coding is a popular way of helping learners understand visualizations and has been found to aid in learning with detailed visualizations. However, previous research has shown that color coding must not always be an effective aid, and that it even may reduce retention when used with simple visualizations. This study assessed whether the presence of color coding in learning tests has an effect after having learned using a detailed visualization that either featured color cues or one that did not. The results indicate that color coding helps learners the most if the learning tests also feature color coding. Importantly, learning with color-coded visualizations and being tested without color cues leads to the worst results in retention and transfer tests. Regarding transfer, color coding in the testing visualization boosts performance regardless of the presence of color cues in the learning phase. The results of this study challenge popular perspectives aiming at optimizing learning by removing potential sources of difficulty. Depending on the learning test, it may be more effective to keep a certain level of difficulty in the learning task when learning with digital media.

Meta-analysis of reduced relative feedback frequency effect on motor learning and performance

A fundamental motor learning principle conveyed in textbooks is that augmented terminal feedback frequency differentially affects motor learning and performance. The guidance hypothesis predicts that relative to a reduced frequency of feedback, providing learners with feedback following every practice trial enhances practice performance but degrades subsequent motor learning. This change in effectiveness for each relative feedback frequency is called a reversal effect, and because it is thought that practice variables can have distinct impacts on learning and performance, delayed retention tests are considered the gold standard in motor learning research. The objectives of this meta-analysis were to a) synthesize the available evidence regarding feedback frequency, performance, and motor learning to test whether there are significant changes in effectiveness from acquisition and immediate retention to delayed retention, b) evaluate potential moderators of these effects, and c) investigate the potential influence of publication bias on this literature. We screened 1662 articles found in PubMed and PsycINFO databases as well as with reference tracing and a targeted author search. A final sample of 61 eligible papers were included in the primary analysis (k = 75, N = 2228). Results revealed substantial heterogeneity but no significant moderators, high levels of uncertainty, and no significant effect of reduced feedback frequency at any time point. Further, multilevel analyses revealed no evidence of a significant change in effect from acquisition or immediate retention to delayed retention. Z-curve analysis suggested the included studies were severely underpowered. These results suggest that robust evidence regarding feedback frequency and motor learning is lacking.

Rutaecarpine Increases Anticancer Drug Sensitivity in Drug-Resistant Cells through MARCH8-Dependent ABCB1 Degradation

The overexpression of adenosine triphosphate (ATP)-binding cassette (ABC) subfamily B member 1 (ABCB1; P-glycoprotein; MDR1) in some types of cancer cells is one of the mechanisms responsible for the development of multidrug resistance (MDR), which leads to the failure of chemotherapy. Therefore, it is important to inhibit the activity or reduce the expression level of ABCB1 to maintain an effective intracellular level of chemotherapeutic drugs. In this study, we found that rutaecarpine, a bioactive alkaloid isolated from Evodia Rutaecarpa, has the capacity to reverse ABCB1-mediated MDR. Our data indicated that the reversal effect of rutaecarpine was related to the attenuation of the protein level of ABCB1. Mechanistically, we demonstrated that ABCB1 is a newly discovered substrate of E3 ubiquitin ligase membrane-associated RING-CH 8 (MARCH8). MARCH8 can interact with ABCB1 and promote its ubiquitination and degradation. In short, rutaecarpine increased the degradation of ABCB1 protein by upregulating the protein level of MARCH8, thereby antagonizing ABCB1-mediated MDR. Notably, the treatment of rutaecarpine combined with other anticancer drugs exhibits a therapeutic effect on transplanted tumors. Therefore, our study provides a potential chemotherapeutic strategy of co-administrating rutaecarpine with other conventional chemotherapeutic agents to overcome MDR and improve therapeutic effect.

Turmeric and Fenugreek - Herbal Agents to Alleviate Sickle Cell Disease

Introduction: Sickle cell disease (SCD) is a genetic disorder with autosomal recessive inheritance causing abnormal hemoglobin. It is an important medical problem globally as well as in our community at Eastern province of Saudi Arabia. It accounts for large numbers of morbidity and to a lesser extent mortality. Several natural plant products over the world, which were known in some communities and their traditional healers, were studied and found to have properties in improving SCD manifestation. This research was planned to explore if any plant product under our study could prove being an effective anti-sickling agent for therapeutic use in SCD management. Objectives: Studying the effects of some plants on sickled RBCs as well as comparing between efficacies of these different plants. Material and Methods: The 49 fresh whole blood samples, extracted through venipuncture in EDTA tubes, were collected from known SCD patients whose homozygosity were confirmed by hemoglobin electrophoresis. These patients were not on recent blood transfusion or hydroxyurea, and aged 14 years or above of both sexes on clinical follow up. The dried rhizomes of turmeric (curcuma longa) powder and dried seeds flour of fenugreek (trigonella foenum-graecum) were used to evaluate the reversal type of anti-sickling activity on RBCs. Results: Out of 49 blood samples, 28 (57.1%) samples were from males and 21 (42.9%) samples from females. The average (±SD) age of the cases was 28.2 (±9.97) years with range 14 – 60 years. Significant anti-sickling activity was found using Turmeric rhizomes extract treatment with 66.81% reversal effect, and 61.28% anti-sickling action when fenugreek seeds extract was used. Conclusion: The findings of this study suggest that turmeric (C. longa) rhizome extract and fenugreek seed extract could have promising anti-sickling properties for SCD treatment.

Applying the Global Change App in Different Instruction Settings to Foster Climate Change Knowledge among Student Teachers

This study focuses on learning with the Global Change app, an interactive tool for fostering climate change knowledge. Numerous studies have contributed to the question on what type of instruction is best to achieve learning gains. The findings are mixed. We applied the app in university courses and investigated which instructional setting a discovery learning approach (no supplementary guidance) or an approach that leans more toward direct instruction is more effective (+ supplementary guidance). Thus, we distinguished between conceptual and procedural guidance within our direct instruction approach. Our study was implemented in a digital learning environment with 110 students participating in the study. We applied a 2 × 2 experimental design with different types of guidance as treatment (conceptual and procedural). An online questionnaire was administered in pretest and posttest to measure climate change knowledge as well as different variables. Our results show that the app provided gains in climate change knowledge in a short period of time regardless of treatment. Further, students who received no supplementary guidance acquired more knowledge about climate change than the groups that received supplemental guidance (either conceptual, procedural, or both). Learning gain correlated significantly negatively with cognitive load across the whole sample, but there were no significant differences between groups. This finding might be interpreted in terms of the renowned expertise reversal effect.

A Preliminary Study on the Impact of UCK2 Knockdown in DLD-1 Colorectal Cells Treated with DHODH Inhibitor

Brequinar sodium (BQR) is a well-studied inhibitor of the dihydroorotate dehydrogenase (DHODH) enzyme. Both the DHODH and uridine-cytidine kinase 2 (UCK2) enzymes have been reported to be over-expressed in cancer cells to maintain the cells high demand for DNA and RNA for their proliferation. In this study, we aim to further sensitize cells to the effects of BQR by knocking down the UCK2 activity. In DLD-1 UCK2 knockdown cells, no change in the sensitivity of cells to BQR was observed. Uridine is known to reverse the anti-proliferative effect of DHODH inhibitors via the salvage pathway. We observed abrogation of approximately 30% of the uridine reversal effect in UCK2 knockdown cells compared to the wild type cells. Our finding indicates that the loss of UCK2 activity in the salvage pathway did not enhance the BQR-mediated cell proliferation inhibition but it abrogates the uridine reversal in the cells.