Scripps College

Local field potentials (LFPs) reflect coordination among neural populations, yet their exact relationship to neural computation remains unknown. One exception is the theta rhythm of the rodent hippocampus, which organizes sequential firing among place cells, enabling spike timing to track the animal's path through its environment. But when the animal stops, the theta rhythm becomes irregular, which is assumed to disrupt its ability to carry spatial information. Here we challenge this assumption by developing an artificial neural network that discovers position-tuned theta rhythms (pThetas) from LFPs even in the absence of strong theta oscillations. Using recordings from male rats, we provide evidence that pTheta is distinct from the dominant theta rhythm, while reflecting rhythmic coordination among place cell populations. Our work suggests that weak and intermittent oscillations, as seen in many brain regions and species, can convey information commensurate with population spike codes when decoded using information-based rather than variance-based principles.

The genusStreptococcuscontains some of the most important commensals and pathogens of the human microbiome. To obtain the fatty acids required for cell membranes,Streptococcuseither produce fatty acidsde novothrough the fatty acid biosynthesis (fab) pathway or uptake host fatty acids through the fatty acid kinase (fak) pathway. Although both thefabandfakpathways represent potential therapeutic targets to prevent or treat infection, progress is limited because of an incomplete understanding of taxon-to-taxon variability in streptococcal lipid metabolism. Here, we examined the role ofde novomonounsaturated fatty acid (MUFA) synthesis in physiology and virulence-associated traits inStreptococcus mutans, Streptococcus pyogenes,andStreptococcus pneumoniae,three major pathogens that cause disease at distinct body sites. In all three species, deletion offabMabolished MUFA production and caused severe growth defects, decreased stress tolerance, increased antibiotic susceptibility, and defects in cell viability, morphology, and division. InS. mutans,loss offabMalso markedly reduced competence signaling and production of the mutacin IV bacteriocin. Deletion offabMincreased susceptibility to killing by human neutrophils inS. mutansandS. pneumoniae,but notS. pyogenes. Together, these findings illustrate that MUFA synthesis is broadly important for streptococcal physiology and cell membrane homeostasis, while its contribution to pathogenesis is strongly species- and context-dependent, providing leads to guide development of novel therapeutic and/or preventative strategies.

This paper reads coal as a metonym for London’s social fabric in the writings of police theorist Patrick Colquhoun, the archival reports on the Wapping Coal Riot, and the anti-carceral poetry of William Blake. In 1798, at the behest of the West India Committee, Colquhoun had developed the first modern police force, the Thames River Police, which predated Robert Peel’s metropolitan police by over 20 years. Colquhoun’s “Treatise on the Commerce and Police of the River Thames” (1800) centers on coal in his case for policing. In his argument, coal’s energy economies link domestic affairs with the entire metropolis, making policing a city-wide problem, one that merits public support (and public funding). In reading Colquhoun’s treatise as an example of the entanglement of policing and fossil fuel power, I discuss the relevant literature from the energy humanities that connects fossil energy to the larger extractive ideologies of empire. I also demonstrate how Colquhoun’s figuring of coal builds on but alters portrayals of coal in Jonathan Swift and Anna Barbauld. The final section of this discussion demonstrates how Blake’s Jerusalem (1820) indexes dispersed, atmospheric systems of carceral power and summons dynamic, unpoliceable crowds. Blake’s smoke poetics sketch a limit of generalization, one that recoups figures of pollution and waste to riot against the systems that produce them.

1. Anthropogenic food subsidies can have profound influences on wildlife behavior and health, including exposure to parasites. In many host-macroparasite systems, parasite exposure is tied to foraging behavior, but how different distributions of food subsidy shape macroparasite encounter and population-level impacts is poorly understood. 2. Here we modify a mathematical model of macroparasite transmission to explore how food subsidies could change parasite encounter rates and between-host variation in parasite burdens, reflecting changes in host foraging and conspecific overlap. 3. Hosts experience the highest average parasite abundance, and associated reductions in population size, when food subsidies increase and homogenize parasite encounter rates, for example when hosts center their home ranges on a point food source and overlap with many conspecifics. Conversely, hosts experience the lowest parasite abundance and impacts when subsidies result in lower and more heterogeneous parasite encounter rates, for example when multiple, patchily-distributed subsidies subdivide host populations and increase host commute times to food at the expense of time spent foraging. Even when resources affect other processes such as improving host immunity or fecundity, the overall effect of subsidies on infection is more strongly driven by changes in parasite encounter rates through altered foraging behavior. These patterns are robust to different effect sizes of resource subsidy on foraging and non-foraging parameters. 4. The finding that host foraging behavior strongly influences infection outcomes in environmentally-acquired parasites has implications for the provisioning of wildlife for recreation, conservation, and management. We advocate for distributing food subsidies in ways that reduce artificial aggregation of hosts and the time animals spend at feeding stations, or that reduce environmental parasite encounters while feeding.

As Large Language Models (LLMs) become increasingly integrated into educational and research environments, questions arise regarding their utility in mentoring undergraduate research and supporting classroom instruction. This paper outlines general guidelines for the effective use of LLMs in research and education, including a comparative analysis of various LLMs to evaluate their respective performance in planning interactive lessons. Findings suggest that LLMs can support lesson planning if seeded with ideas for learning objectives that come from additional background research and human ingenuity, iterate to find better interactive activities, and draw from multiple LLMs to avoid the typical weaknesses of a single LLM. In research mentoring, LLMs support efficient and high-quality output if one can engineer a suitable prompt, aided by background knowledge from some other source. The biggest barrier to LLM effectiveness is their confident hallucinations and lack of accuracy and creativity, but guidelines are provided here that should allow users to get beyond the pedestrian and sometimes incorrect output of the LLMs. LLMs should not replace human instruction and mentorship, but rather, should be seen as supplements that demand informed and reflective use. <em>Primary Image:</em>&nbsp;Can a professor be replaced with a Large Language Model? It could democratize education. We investigate the benefits and pitfalls of doing so.

Abstract We propose a new computational-level objective function for theoretical biology and theoretical neuroscience that combines: reinforcement learning, the study of learning with feedback via rewards; rate-distortion theory, a branch of information theory that deals with compressing signals to retain relevant information; and computational mechanics, the study of minimal sufficient statistics of prediction, also known as causal states. We highlight why this proposal is likely only an approximation, but is likely to be an interesting one, and propose a new algorithm for evaluating it to obtain the newly coined ‘reward-rate manifold’. The performance of real and artificial agents in partially observable environments can be newly benchmarked using these reward-rate manifolds. To that end, we calculate an example reward-rate manifold utilizing new equations reminiscent of the Blahut–Arimoto algorithm and propose a general algorithm for computing reward-rate manifolds. Finally, we describe experiments that can probe whether or not biological organisms are resource-rational reinforcement learners, using as an example maximin strategies, as bacteria have been shown to be approximate maximiners—doing their best in the worst-case environment, regardless of what is actually happening. This proposal explains why ‘good enough’ for organisms might actually be near-optimal, if viewed correctly.

Prior scholarship has helped demonstrate therapists' perceptions of the value of discussing anti-Black racism with Black clients in a manner that espouses cultural comfort or the ability to be at ease when discussing lived experiences related to clients' culture during treatment. Better understanding cultural comfort, an aspect of multicultural orientation, when discussing anti-Black racism with Black clients could help clarify paths by which psychotherapy does not perpetuate harm reflected in the dehumanization of such racism. However, Black clients' perspectives are missing in the literature. As such, we collected data from 153 Black participants with recent therapy experiences. They were asked about discussing anti-Black racism during therapy, satisfaction/helpfulness of these conversations, and items related to initiation and frequency of such discussions. Participants also completed measures of cultural comfort, working alliance, and perceived outcome. Perceived therapist cultural comfort did not significantly vary if anti-Black racism was discussed, and discussing anti-Black racism did not moderate the relationship between cultural comfort and working alliance or cultural comfort and outcome. Satisfaction and helpfulness positively correlated with cultural comfort. Cultural comfort scores also varied by who initiated these conversations and their frequency. We contextualize these findings in a need for greater nuance with respect to examining discussions of racism in psychotherapy and consider our findings with respect to broaching literature. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Abstract We present a pedagogical, perturbation-based derivation of the cosmological Gurzadyan’s theorem, accessible to advanced high-school and undergraduate students.

<title>Abstract</title> Invasive species are a leading cause of global biodiversity loss, and in Southern California scrublands, black mustard ( <italic>Rhamphospermum nigrum</italic> ) is a prominent, harmful invasive plant. <italic>Rhamphospermum nigrum</italic> employs allelopathic <italic>Novel Weapons</italic> to directly harm heterospecifics via inhibition of germination and indirectly by killing mycorrhizae, generating near monocultures across hillsides. However, active carbon, often deposited by wildfires, is known to bond to and neutralize plant exudates. This led to a hypothesis that active carbon soil amendments neutralize <italic>R. nigrum Novel Weapons</italic> , and thus, the invasive’s superior competitiveness. In the greenhouse and field, carbon treatments reduced or completely inhibited <italic>R. nigrum</italic> reproductive potential (Inflorescence) and mitigated some of the invasive’s negative effects on the growth of deerweed ( <italic>Acmispon glaber</italic> ), a common Southern California native “fire-follower”. Carbon soil amendments, whether administered by hand or by fire, may thus reduce the fitness, abundance, and negative effects of <italic>R. nigrum</italic> on the native plant community.