Generating complex 3D structures in soft materials
Biomimetics of plant and animal tissue morphogenesis.
In plants and animals, soft living tissues routinely adopt complex 3D structures to perform or enhance critical functions. Although such structures have applications in biomedical engineering, robotics, and flexible electronics, most efforts to synthesize them in soft materials diverge fundamentally from biological processes. Changjin Huang et al. (pp. 70–74) present a technique to direct the polymerization of monomers to form complex 3D architectures from porous hydrogels. Mimicking organic tissue morphogenesis, in which constituents within a single tissue grow at different rates and impose mechanical restraints, the technique modulates oxygen diffusion-inhibited polymerization to enable the formation of engineered heterogeneous, patterned structures. Depending on the patterning, the prefabricated structures self-organize and evolve into a desired configuration. The authors used the technique to generate a variety of biomimetic structures corresponding to plant and animal tissues, including bending in a plant stem and structural changes seen in the respiratory airways of asthma patients. The findings offer an approach to study and replicate complex soft tissue architectures, according to the authors. — T.J.
Characterizing combinations of anti-HCV antibodies
No single broadly neutralizing monoclonal antibody can neutralize all the strains of hepatitis C virus (HCV), and developing a vaccine against HCV may thus require the induction of multiple neutralizing monoclonal antibodies (NAbs) that target different epitopes. Madeleine Mankowski et al. (pp. E82–E91) examined the neutralization profiles of 12 human NAbs that target distinct epitopes on the HCV E2 envelope protein. The NAbs segregated into two distinct neutralization clusters, and the authors tested the neutralizing breadth of all 35 possible combinations that included one NAb from each neutralization cluster against 11 diverse genotype 1 HCV pseudoparticles. The authors found that many NAb combinations showed greater neutralizing breadth than any individual NAb. One combination, designated HEPC74/HEPC98, was particularly broadly neutralizing and also displayed increased potency compared with its component NAbs. Neutralization with this combination matched the predictions of an analytical model for drug combinations, suggesting that these NAbs inhibit HCV infection through independent mechanisms. The authors investigated the inhibitory mechanisms of HEPC74/HEPC98 and found that its component NAbs blocked virus binding to three different HCV receptors. According to the authors, the dependence of HCV on multiple cell surface receptors could prove to be a critical vulnerability, and inducing multiple NAbs with distinct neutralization profiles could serve as a promising approach for developing a broadly neutralizing anti-HCV vaccine. — S.R.
Bias in self-reported feelings and behaviors
Daily diary anxiety reports from bar examinees showing initial elevation effects.
Numerous scientific disciplines rely on individuals to assess and report their thoughts, feelings, and behaviors. Curiously, self-reported mental and physical states often trend downward over time, a well-documented but poorly understood pattern known as the attenuation effect, which implies that follow-up reports show declining trends over time. Noting that this pattern may instead reflect a tendency for initial reports to be biased upward, Patrick Shrout et al. (pp. E15–E23) designed four field experiments encompassing more than 2,200 participants to distinguish between the two explanations. Based on daily diary reports of moods and symptoms from law graduates preparing for the bar examination, college students preparing for exams, and bimonthly surveys of college roommates, the authors found effects consistent with an initial elevation bias in self-reports, rather than a later decline. Furthermore, the analysis revealed that the bias operated both within and between individuals, and that the bias was more pronounced for emotional states than for behaviors. The bias was also more pronounced for negative mental and physical symptoms, compared with positive symptoms. The finding that self-assessments can exhibit an initial upward bias carries implications for research practices across a range of disciplines and may challenge the validity of studies that rely on a single assessment, according to the authors. — T.J.
Role of picture languages in mathematics
Since Euclid first laid out the framework for his eponymous system of geometry, mathematicians have used pictures to pose and solve problems and communicate new insights. Pictures represent a critical tool for researchers to analyze and cross-link abstract ideas in disciplines such as topology and quantum field theory. Arthur Jaffe and Zhengwei Liu (pp. 81–86) reevaluate the fundamental intersection between pictures and mathematics and outline a possible framework for using picture languages to unify ideas from different fields. The framework differentiates two core aspects of mathematical pictures—a theory of mathematical analysis for pictures and its application within established mathematical systems, a distinction between abstraction and concrete simulation akin to the linguistic difference between syntax and semantics. Using a language called quon, which was invented to study quantum information, the authors demonstrate how picture languages can be used to derive proofs and new identities including a topological interpretation of a common quantum teleportation protocol. The study also raises questions to stimulate thought and drive future analysis of quon and other useful mathematical picture languages, according to the authors. — T.J.