The Intradermal Reaction in Amebiasis

Studies on the amebiasis skin test were carried out in Amerindians living on reserves of Northern Saskatchewan. Results indicate the skin test to be highly sensitive in patients with acute amebic dysentery and in individuals with a history of amebic disease. A high percentage of asymptomatic school children living on a reserve where amebic disease is of common occurrence were also skin reactors. In a similar group of school children living on a reserve where amebic disease had never been reported but where E. histolytica infection rates are high there were very few reactors. A control group of white adults living in a non-endemic area were uniformly negative to the skin test. A comparison with the indirect hemagglutination test showed a good general correlation, but the skin test proved to be more accurate in cases of acute amebic dysentery in children 5 years of age or under. The skin test appears to have potential as a diagnostic technique and may be of considerable value in defining endemic areas of amebic disease.     

Probabilistic Analysis of Pattern Formation in Monotonic Self-Assembly

Inspired by biological systems, self-assembly aims to construct complex structures. It functions through piece-wise, local interactions among component parts and has the potential to produce novel materials and devices at the nanoscale. Algorithmic self-assembly models the product of self-assembly as the output of some computational process, and attempts to control the process of assembly algorithmically. Though providing fundamental insights, these computational models have yet to fully account for the randomness that is inherent in experimental realizations, which tend to be based on trial and error methods. In order to develop a method of analysis that addresses experimental parameters, such as error and yield, this work focuses on the capability of assembly systems to produce a pre-determined set of target patterns, either accurately or perhaps only approximately. Self-assembly systems that assemble patterns that are similar to the targets in a significant percentage are “strong” assemblers. In addition, assemblers should predominantly produce target patterns, with a small percentage of errors or junk. These definitions approximate notions of yield and purity in chemistry and manufacturing. By combining these definitions, a criterion for efficient assembly is developed that can be used to compare the ability of different assembly systems to produce a given target set. Efficiency is a composite measure of the accuracy and purity of an assembler. Typical examples in algorithmic assembly are assessed in the context of these metrics. In addition to validating the method, they also provide some insight that might be used to guide experimentation. Finally, some general results are established that, for efficient assembly, imply that every target pattern is guaranteed to be assembled with a minimum common positive probability, regardless of its size, and that a trichotomy exists to characterize the global behavior of typical efficient, monotonic self-assembly systems in the literature.     

Broadband Plasmonic Photocurrent Enhancement in Planar Organic Photovoltaics Embedded in a Metallic Nanocavity

A substantial broadband increase in the external quantum efficiency (EQE) of thin‐film organic photovoltaic (OPV) devices using near‐field coupling to surface plasmons is reported, significantly enhancing absorption at surface plasmon resonance (SPR). The devices tested consist of an archetypal boron subpthalocyanine chloride/fullerene (SubPc/C₆₀) donor/acceptor heterojunction embedded within a planar semitransparent metallic nanocavity. The absorption and EQE are modeled in detail and probed by attenuated total internal reflection spectroscopy with excellent agreement. At SPR, the EQE can be enhanced fourfold relative to normal incidence, due to simulated ninefold enhancement in active layer absorption efficiency. The response at SPR is thickness‐independent, down to a few monolayers, suggesting the ability to excite monolayer‐scale junctions with an EQE of ≈6% and a 16‐fold absorption enhancement over normal incidence. These results potentially impact the future design of plasmonically enhanced thin‐film photovoltaics and photodetectors and enable the direct analysis of the dynamics of photocurrent production at OPV heterojunctions.     

The Ca2+ Sensor Protein Swiprosin-1/EFhd2 Is Present in Neurites and Involved in Kinesin-Mediated Transport in Neurons

Swiprosin-1/EFhd2 (EFhd2) is a cytoskeletal Ca²⁺ sensor protein strongly expressed in the brain. It has been shown to interact with mutant tau, which can promote neurodegeneration, but nothing is known about the physiological function of EFhd2 in the nervous system. To elucidate this question, we analyzed EFhd2^−/−/lacZ reporter mice and showed that lacZ was strongly expressed in the cortex, the dentate gyrus, the CA1 and CA2 regions of the hippocampus, the thalamus, and the olfactory bulb. Immunohistochemistry and western blotting confirmed this pattern and revealed expression of EFhd2 during neuronal maturation. In cortical neurons, EFhd2 was detected in neurites marked by MAP2 and co-localized with pre- and post-synaptic markers. Approximately one third of EFhd2 associated with a biochemically isolated synaptosome preparation. There, EFhd2 was mostly confined to the cytosolic and plasma membrane fractions. Both synaptic endocytosis and exocytosis in primary hippocampal EFhd2^−/− neurons were unaltered but transport of synaptophysin-GFP containing vesicles was enhanced in EFhd2^−/− primary hippocampal neurons, and notably, EFhd2 inhibited kinesin mediated microtubule gliding. Therefore, we found that EFhd2 is a neuronal protein that interferes with kinesin-mediated transport.     

Usp18 Driven Enforced Viral Replication in Dendritic Cells Contributes to Break of Immunological Tolerance in Autoimmune Diabetes

Infection with viruses carrying cross-reactive antigens is associated with break of immunological tolerance and induction of autoimmune disease. Dendritic cells play an important role in this process. However, it remains unclear why autoimmune-tolerance is broken during virus infection, but usually not during exposure to non-replicating cross-reactive antigens. Here we show that antigen derived from replicating virus but not from non-replicating sources undergoes a multiplication process in dendritic cells in spleen and lymph nodes. This enforced viral replication was dependent on Usp18 and was essential for expansion of autoreactive CD8⁺ T cells. Preventing enforced virus replication by depletion of CD11c⁺ cells, genetically deleting Usp18, or pharmacologically inhibiting of viral replication blunted the expansion of autoreactive CD8⁺ T cells and prevented autoimmune diabetes. In conclusion, Usp18-driven enforced viral replication in dendritic cells can break immunological tolerance and critically influences induction of autoimmunity.     

A Foraminiferal Parasite on the Sea Urchin Echinocorys: Ichnological Evidence from the Late Cretaceous (Lower Maastrichtian,Northern Germany)

Archaeonassa is a poorly known ichnogenus, originally described from the Cambrian of North America, which is a member of the Scolicia ’group’, but can be regarded as distinct from Scolicia. Archaeonassa was originally based on modern material, and therefore falls into a taxonomic grey zone concerning its availability, but as A. fossulata was erected on fossil material the ichnogenus is here retained. Although exhibiting a degree of morphological plasticity in its style of ornament, Archaeonassa is considered to be monospecific, with only the ichnospecies A. fossulata recognised. The ichnogenus appears to be restricted to the Paleozoic, although similar material is well documented from modern environments. Thus the ichnogenus is expected to be geographically and stratigraphically more widespread than it otherwise appears. Archaeonassa is a valuable tool for environmental reconstruction within the Paleozoic as it occurs within intertidal deposits. The ichnogenus is interpreted chiefly as the work of gastropods, although in many cases may have been produced by trilobites or even echinoids, and represents the exogenic expression of either surface or shallow subsurface locomotion.     

Focus: Preventive Medicine: Who is Biking for? Urban Bikeshare Networks’ Responses to the COVID-19 Pandemic,Disparities in Bikeshare Access,and a Way Forward

Black, Latinx, and Indigenous people have contracted the SARS-CoV-2 virus and died of COVID-19 at higher rates than White people. Individuals rated public transit, taxis, and ride-hailing as the modes of transportation putting them at greatest risk of COVID-19 infection. Cycling may thus be an attractive alternative for commuting. Amid the increase in bikeshare usage during the early months of the pandemic, bikeshare companies made changes to membership requirements to increase accessibility, targeting especially essential workers. Essential workers in the United States are disproportionately Black and Latinx, underpaid, and reliant on public transit to commute to work. We document changes made by bikeshare companies, including benefits to various groups of essential workers, and we discuss such changes in the context of longstanding racial disparities in bikeshare access. While well intended, the arbitrary delineation in eligibility for such benefits by class of essential workers unwittingly curtailed access for many who may have benefited most. Given that equity in bikeshare is an important tool to improve access to safe transportation, critical changes in the distribution, accessibility, and usability of bikeshare networks is essential. Bikeshare companies, city planners, and policy makers should collaborate with community-based bike advocates to implement changes, as vocalized by those most in need of alternative forms of transportation.