Although grid cells are one of the most well-studied functional classes of neurons in the mammalian brain, whether there is a single orientation and spacing value per grid module has not been carefully tested. We analyze a recent large-scale recording of medial entorhinal cortex to characterize the presence and degree of heterogeneity of grid properties within individual modules. We find evidence for small, but robust, variability and hypothesize that this property of the grid code could enhance the encoding of local spatial information. Performing analysis on synthetic populations of grid cells, where we have complete control over the amount heterogeneity in grid properties, we demonstrate that grid property variability of a similar magnitude to the analyzed data leads to significantly decreased decoding error. This holds even when restricted to activity from a single module. Our results highlight how the heterogeneity of the neural response properties may benefit coding and opens new directions for theoretical and experimental analysis of grid cells.
Droughts are a natural hazard of growing concern as they are projected to increase in frequency and severity for many regions of the world. The identification of droughts and their future characteristics is essential to building an understanding of the geography and magnitude of potential drought change trajectories, which in turn is critical information to manage drought resilience across multiple sectors and disciplines. Adding to this effort, we developed a dataset of global historical and projected future drought indices over the 1980-2100 period based on downscaled CMIP6 models across multiple shared socioeconomic pathways (SSP). The dataset is composed of two indices: the Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) for 23 downscaled global climate models (GCMs) (0.25-degree resolution), including historical (1980-2014) and future projections (2015-2100) under four climate scenarios: SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5. The drought indices were calculated for 3-, 6- and 12-month accumulation timescales and are available as gridded spatial datasets in a regular latitude-longitude format at monthly time resolution.
Electrochemical aptamer-based (EAB) sensors are a molecular measurement platform that enables the continuous, real-time measurement of a wide range of drugs and biomarkers in situ in the living body. EAB sensors are fabricated by depositing a thiol-modified, target-binding aptamer on the surface of a gold electrode, followed by backfilling with an alkanethiol to form a self-assembled monolayer. And while the majority of previously described EAB sensors have employed hydroxyl-terminated monolayers, a handful of studies have shown that altering the monolayer headgroup can strongly affect sensor performance. Here, using 4 different EAB sensors, we show that the mixed monolayers composed of mixtures of 6-carbon hydroxyl-terminated thiols and varying amounts of either 6- or 8-carbon, carboxylate-terminated thiols lead to improved EAB sensor performance. Specifically, the use of such mixed monolayers enhances the signal gain (the relative change in the signal seen upon target addition) for all tested sensors, often by several fold, both in buffer and whole blood at room temperature or physiological temperatures. Moreover, these improvements in gain are achieved without significant changes in the aptamer affinity or the stability of the resulting sensors. In addition to proving a ready means of improving EAB sensor performance, these results suggest that exploration of the chemistry of the electrode surface employed in such sensors could prove to be a fruitful means of advancing this unique in vivo sensing technology.
Chemical upcycling of polyethylene (PE) to long-chain alkylaromatics through tandem hydrocracking/aromatization has potential to provide value-added chemicals. However, the liquid product is a complex mixture of alkanes, alkylbenzenes, and polyaromatics, limiting its direct usability. The most valuable component of the product mixture is the alkylbenzenes because of their potential as precursors to anionic surfactants. In this study, a one-pot reactive separation is described. Sulfonating the product mixture from PE upcycling with silica sulfuric acid followed by neutralization with sodium hydroxide yields sodium alkylbenzenesulfonates (up to 93 mol % selectivity), along with a separate phase of lubricant-range hydrocarbons as a coproduct. Compared to petroleum-based sodium dodecylbenzenesulfonates, the reported PE-derived surfactant molecules show competitive physicochemical properties, including surface tension and interfacial tension. According to life cycle assessment, the described reaction strategy demonstrates 20% lower greenhouse gas emissions, when considering uses for the coproducts of PE upcycling, compared to conventional linear alkylbenzenesulfonates (LAS) manufacturing directly from petrochemical feedstocks.
Abstract: I love you is among the most meaningful utterances in English speakers’ organization of intimacy, yet remains understudied by scholars of language. This article investigates metapragmatic discourse about the first exchange of I love you between romantic partners using data from the social media platform Reddit. The discourse reveals a normative model in which I love you functions not only as an expression of emotion but a speech act that is ideologically constructed as committing the speaker and inviting the listener onto a relationship path that includes monogamy, long-term commitment, and eventually cohabitation and marriage. Normative discourses about and practices surrounding I love you thereby bolster the hypervalorization of romantic relationships, the validation of jealousy and possessiveness as expressions of love, and the naturalization of monogamy and normative Western family structures. Drawing on discourses of polyamory, asexuality, and disability/neurodivergence, we point to alternative possibilities for love’s meaning and expression.
Abstract: Despite increasing racial diversity in the United States, and the particular growth of multiracial populations, questions about how children perceive others’ (bi)racial identities remain poorly understood. In two preregistered studies, we asked White and racially minoritized American children (N = 157; 4–11‐years old) and White and multiracial adults (N = 226) how acceptable it was for monoracial people (Black or White; Study 1) and/or biracial people (Black–White; Studies 1 and 2) to claim either a monoracial or biracial identity. Consistent with past research with adults, children said that monoracial people should claim (only) the monoracial identity which matched their ancestry. Judgements about biracial identity were more variable. White and multiracial adults (Study 2) reported that biracial targets could claim a racial identity that matched either or both of their parents, with biracial claims being evaluated most positively. Exploratory analyses on children's judgements about biracial people's identity claims (Study 1) revealed different patterns of development for White children and children from minoritized backgrounds. Whereas White children became more likely with age to report that all identity claims were acceptable, children from racially minoritized groups became more likely with age to endorse biracial targets who claimed a biracial identity. These findings suggest that children's own racial background and age may have a larger impact on their perceptions of biracial people's identities, compared to their perceptions of monoracial people's identities.
Studying comorbidities in early onset Alzheimer disease (AD) may provide an advantageous perspective on their pathogenesis because aging factors may be largely inoperative for these subjects. We compared AD comorbidities between early-onset sporadic cases and American and Colombian cases with PSEN1 mutations. AD neuropathological changes (ADNC) were very severe in all groups but more severe in the PSEN1 groups. Lewy body disease and cerebral white matter rarefaction were the most common (up to 60%) of AD comorbidities, followed by arteriolosclerosis (up to 37%), and large-vessel atherosclerosis (up to 20%). Differences between the 3 groups included earlier age of onset in the American PSEN1 cases, shorter disease duration in sporadic cases, and more frequent large-vessel atherosclerosis and cerebral amyloid angiopathy in the Colombian PSEN1 cases. Logistic regression models adjusted for age and sex found the presence of a PSEN1 mutation, an apolipoprotein ε4 allele and TDP-43 pathology to predict an earlier age of onset; Hispanic ethnicity and multiracial subjects were predictive of severe CAA. Comorbidities are common in early onset AD and should be considered when planning clinical trials with such subjects. However, they may be at least partially dependent on ADNC and thus potentially addressable by anti-amyloid or and/anti-tau therapies.
