Peer-assisted learning (PAL) can have both benefits and costs when compared to individual learning. In an empirical study aimed at testing whether PAL yields better learning outcomes than individual learning in a set of insight problems from the Remote Associates Test (RAT), participants in the PAL condition learned from interacting with scripted peers and outperformed participants in the individual learning condition. Although interaction was limited, there is evidence for knowledge spillover from peers as a cognitive mechanism in PAL. The peer-assisted learning transferred to a final test that was completed individually. The benefit of peer-assisted learning persisted in spite of significantly greater error exposure in the PAL condition. In addition, the superiority of peer-assisted learning over individual learning was more pronounced for the more difficult RAT problems. These findings suggest that PAL may be an effective approach to developing insight problem solving skills.

The structure, physiology, and fate of living cells are all highly sensitive to mechanical forces in the cellular microenvironment, including stresses and strains that originate from encounters with the extracellular matrix (ECM), blood and other flowing materials, and neighbouring cells. This relationship between context and physiology bears tremendous implications for the design of cellular micro-or nanotechnologies, since any attempt to control cell behavior in a device must provide the appropriate physical microenvironment for the desired cell behavior. Cells sense, process, and respond to biophysical cues in their environment through a set of integrated, multi-scale structural complexes that span length scales from single molecules to tens of microns, including small clusters of force-sensing molecules at the cell surface, micron-sized cell-ECM focal adhesion complexes, and the cytoskeleton that permeates and defines the entire cell. This review focuses on several key technologies that have recently been developed or adapted for the study of the dynamics of structural micro-and nanosystems in living cells and how these systems contribute to spatially-and temporally-controlled changes in cellular structure and mechanics. We begin by discussing subcellular laser ablation, which permits the precise incision of nanoscale structural elements in living cells in order to discern their mechanical properties and contributions to cell structure. We then discuss fluorescence recovery after photobleaching and fluorescent speckle microscopy, two live-cell fluorescence imaging methods that enable quantitative measurement of the binding and transport properties of specific proteins in the cell. Finally, we discuss methods to manipulate cellular structural networks by engineering the extracellular environment, including microfabrication of ECM distributions of defined geometry and microdevices designed to measure cellular traction forces at micron-scale resolution. Together, these methods form a powerful arsenal that is already adding significantly to our understanding of the nanoscale architecture and mechanics of living cells and may contribute to the rational design of new cellular micro-and nanotechnologies.

Multiple magnetic skyrmion phases add an additional degree of freedom for skyrmion-based ultrahigh-density spin memory devices. Extending the field to 2D van der Waals magnets is a rewarding challenge, where the realizable degree of freedoms (e.g., thickness, twist angle, and electrical gating) and high skyrmion density result in intriguing new properties and enhanced functionality. In this work, a van der Waals interface, formed by two 2D ferromagnets Cr₂ Ge₂ Te₆ and Fe₃ GeTe₂ with a Curie temperature of ≈65 and ≈205 K, respectively, hosting two groups of magnetic skyrmions, is reported. Two sets of topological Hall effect signals are observed below 6s0 K when Cr₂ Ge₂ Te₆ is magnetically ordered. These two groups of skyrmions are directly imaged using magnetic force microscopy, and supported by micromagnetic simulations. Interestingly, the magnetic skyrmions persist in the heterostructure with zero applied magnetic field. The results are promising for the realization of skyrmionic devices based on van der Waals heterostructures hosting multiple skyrmion phases.

Combined inhibition of ribonucleotide reductase and deoxycytidine kinase (dCK) in multiple cancer cell lines depletes deoxycytidine triphosphate pools leading to DNA replication stress, cell cycle arrest, and apoptosis. Evidence implicating dCK in cancer cell proliferation and survival stimulated our interest in developing small molecule dCK inhibitors. Following a high throughput screen of a diverse chemical library, a structure-activity relationship study was carried out. Positron Emission Tomography (PET) using (18)F-L-1-(2'-deoxy-2'-FluoroArabinofuranosyl) Cytosine ((18)F-L-FAC), a dCK-specific substrate, was used to rapidly rank lead compounds based on their ability to inhibit dCK activity in vivo. Evaluation of a subset of the most potent compounds in cell culture (IC50 = ∼1-12 nM) using the (18)F-L-FAC PET pharmacodynamic assay identified compounds demonstrating superior in vivo efficacy.

Combined inhibition of ribonucleotide reductase and deoxycytidine kinase (dCK) in multiple cancer cell lines depletes deoxycytidine triphosphate pools leading to DNA replication stress, cell cycle arrest, and apoptosis. Evidence implicating dCK in cancer cell proliferation and survival stimulated our interest in developing small molecule dCK inhibitors. Following a high throughput screen of a diverse chemical library, a structure-activity relationship study was carried out. Positron Emission Tomography (PET) using (18)F-L-1-(2'-deoxy-2'-FluoroArabinofuranosyl) Cytosine ((18)F-L-FAC), a dCK-specific substrate, was used to rapidly rank lead compounds based on their ability to inhibit dCK activity in vivo. Evaluation of a subset of the most potent compounds in cell culture (IC50 = ∼1-12 nM) using the (18)F-L-FAC PET pharmacodynamic assay identified compounds demonstrating superior in vivo efficacy.

Emergent physical properties often arise at interfaces of complex oxide heterostructures due to the interplay between various degrees of freedom, especially those with polar discontinuities. It is desirable to explore if these structures may generate pure and controllable spin currents, which are needed to attain unmatched performance and energy efficiency in the next-generation spintronic devices. Here we report the emergence of a spin-polarized two-dimensional electron gas (SP-2DEG) at the interface of two insulators, SrTiO3 and PbZr0.2Ti0.8O3. This SP-2DEG is strongly localized at the interfacial Ti atoms, due to the interplay between Coulomb interaction and band bending, and can be tuned by the ferroelectric polarization. Our findings open a door for engineering ferroelectric/insulator interfaces to create tunable ferroic orders for magnetoelectric device applications and provide opportunities for designing multiferroic materials in heterostructures.

Magnetic transition metal chalcogenides form an emerging platform for exploring spin-orbit driven Berry phase phenomena owing to the nontrivial interplay between topology and magnetism. Here we show that the anomalous Hall effect in pristine Cr2Te3 thin films manifests a unique temperature-dependent sign reversal at nonzero magnetization, resulting from the momentum-space Berry curvature as established by first-principles simulations. The sign change is strain tunable, enabled by the sharp and well-defined substrate/film interface in the quasi-two-dimensional Cr2Te3 epitaxial films, revealed by scanning transmission electron microscopy and depth-sensitive polarized neutron reflectometry. This Berry phase effect further introduces hump-shaped Hall peaks in pristine Cr2Te3 near the coercive field during the magnetization switching process, owing to the presence of strain-modulated magnetic layers/domains. The versatile interface tunability of Berry curvature in Cr2Te3 thin films offers new opportunities for topological electronics.

The exploration of 1D magnetism, frequently portrayed as spin chains, constitutes an actively pursued research field that illuminates fundamental principles in many-body problems and applications in magnonics and spintronics. The inherent reduction in dimensionality often leads to robust spin fluctuations, impacting magnetic ordering and resulting in novel magnetic phenomena. Here, structural, magnetic, and optical properties of highly anisotropic 2D van der Waals antiferromagnets that uniquely host spin chains are explored. First-principle calculations reveal that the weakest interaction is interchain, leading to essentially 1D magnetic behavior in each layer. With the additional degree of freedom arising from its anisotropic structure, the structure is engineered by alloying, varying the 1D spin chain lengths using electron beam irradiation, or twisting for localized patterning, and spin textures are calculated, predicting robust stability of the antiferromagnetic ordering. Comparing with other spin chain magnets, these materials are anticipated to bring fresh perspectives on harvesting low-dimensional magnetism.

Background

An analysis of cardiac injury markers in patients with OSA who sustain an episode of acute coronary syndrome (ACS) may contribute to a better understanding of the interactions and impact of OSA in subjects with ACS. We compared peak cardiac troponin I (cTnI) levels in patients with OSA and patients without OSA who were admitted for ACS.

Methods

Blood samples were collected every 6 hours from the time of admission until two consecutive assays showed a downward trend in the cTnI assay. The highest value obtained defined the peak cTnI value, which provides an estimate of infarct size.

Results

We included 89 patients with OSA and 38 patients without OSA with an apnea-hypopnea index of a median of 32 (interquartile range [IQR], 20.8-46.6/h and 4.8 [IQR, 1.6-9.6]/h, respectively. The peak cTnI value was significantly higher in patients without OSA than in patients with OSA (median, 10.7 ng/mL [IQR, 1.78-40.1 ng/mL] vs 3.79 ng/mL [IQR, 0.37-24.3 ng/mL]; P = .04). The multivariable linear regression analysis of the relationship between peak cTnI value and patient group, age, sex, and type of ACS showed that the presence or absence of OSA significantly contributed to the peak cTnI level, which was 54% lower in patients with OSA than in those without OSA.

Conclusions

The results of this study suggest that OSA has a protective effect in the context of myocardial infarction and that patients with OSA may experience less severe myocardial injury. The possible role of OSA in cardioprotection should be explored in future studies.